VOCATIONAL TRAINING REPORT SOURADEEP BHATTACHARJA
INDIAN INSTITUTE OF TECHNOLOGY (INDIAN SCHOOL OF MINES)
TABLE OF CONTENTS
02 04 07 08
09 20 21 22 27
32 40 45 53 57
62 67
Acknowledgement Here I would like to take this opportunity to thank all those who have been instrumental in providing me an enriching experience in this esteemed company. I can say that I have picked up some valuable skills that would surely help me adapt better to the industry. Something that specifically appealed to me was that how different the industry is when compared to our theory. I have learnt about turbines, pumps etc. as a part of my course material and I was perfectly happy with the theoretical aspects until I saw what happens in the real world. Here I was shown how those basics that I learnt at college have to be applied in actual industry, I was taught quite a few thumb rules that industrial experts rely on to do their jobs correctly. I was also imparted with the skills of handling industrial problems at mammoth scales. My theoretical problems involved machinery primarily on a lab scale, however here I was taught what other considerations come into effect when the scale becomes roughly a thousand times or more of the laboratory size. A lot of assumptions that I was used to making earlier do not hold in real life and I understood the importance of being precise and accurate. Lastly, I realised what it meant to be an engineer. I saw what engineers do for the nation, though people might not realise it, engineers sacrifice a lot for our nation, they build our nation, they silently work behind the scenes and turn our dreams into reality, the steel, the roads, the aircrafts, the cars, the power plants, everything in this whole wide world has a touch of engineering in it and some engineer’s hard work behind it. I am really happy and proud that I chose this noble profession. Hence, I can sum up by saying that I gained a lot in this limited time and I would want to thank my guide cum mentors, Mr. Mahadeo Oraon, Mrs. Abhisita Chakraborty and Mr. Mrinal Banerjee for giving me this great opportunity and supporting me throughout the period of my stay. Souradeep Bhattacharja, Indian Institute of Technology (Indian School of Mines), Dhanbad.
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IOCL HALDIA REFINERY MECHANICAL MAINTENANCE PLANNING CELL
SL. NO.
UNIT
1
Workshop
2
FOB
3
TPS
SITE OFFICER
Mr. Debdyut De, DMML / Mr. Amal B. Das, AM(ML) Mr. Vikash Kumar, AM(ML) / Mr. B. Mete, SMLE Mr. Arun K. Gupta, AM(ML)
WORKING DAYS
SIGNATURE
3
3
2
Mr. Subhendu Mondal, 4
LOB
MNM / Mr. Tanmay Sarkar,
3
AM(ML) 5
OM & S
Md. Tanbir Haider, DMML
3
6
DHDS
Mr. Himagna Sen, AM(ML)
3
7
ETP
Mr. Vivekanand, MLE
3
8
OHCU
Mr. Dilip Kumar, DMML
3
9
Garage
Mr. D. K. Parua, AM(ML)
3
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Introduction Indian Oil Corporation Ltd. (IOC) is the flagship national oil company in the downstream sector. The Indian Oil Group of companies owns and operates 10 of India's 19 refineries with a combined refining capacity of 1.2 million barrels per day. These include two refineries of subsidiary Chennai Petroleum Corporation Ltd. (CPCL) and one of Bongaigaon Refinery and Petrochemicals Limited (BRPL). The 10 refineries are located at: •
Guwahati
•
Barauni
•
Koyali
•
Haldia
•
Mathura
•
Digboi
•
Panipat
•
Chennai
•
Narimanam
•
Bongaigaon
Indian Oil's cross-country crude oil and product pipelines network span over 9,300 km. It operates the largest and the widest network of petrol & diesel stations in the country, numbering around 16455. Indian Oil Corporation Ltd. (Indian Oil) was formed in 1964 through the merger of Indian Oil Company Ltd and Indian Refineries Ltd. Indian Refineries Ltd was formed in 1958, with Feroze Gandhi as Chairman and Indian Oil Company Ltd. was established on 30th June 1959 with Mr S. Nijalingappa as the first Chairman. In 1964, Indian Oil commissioned Barauni Refinery and the first petroleum product pipeline from Guwahati. In 1965, Gujarat Refinery was inaugurated. In 1967, Haldia-Baraurii Pipeline (HBPL) was commissioned. In 1972, Indian Oil launched SERVO, the first indigenous lubricant. In 1974, Indian Oil Blending Ltd. (IOBL) became the wholly owned subsidiary of Indian Oil. In 1975, Haldia Refinery was commissioned. In 1981, Digboi Refinery and Assam Oil Company's (AOC) marketing operations came under the control of Indian Oil. In 1982, Mathura Refinery and Mathura-Jalandhar Pipeline (MJPL) were commissioned. In 1994, India's First Hydrocracker Unit was commissioned at Gujarat Refinery.
In 1995, 1,443 km. long Kandla-Bhatinda Pipeline (KBPL) was commissioned at Sanganer. In 1998, Panipat Refinery was commissioned. In the same year, Haldia- Barauni Crude Oil Pipeline (HBCPL) was completed. In 2000, Indian Oil crossed the turnover of Rs 1,00,000 crore and Page | 4
became the first Corporate in India to do so. In the same year, Indian Oil entered into Exploration & Production (E&P) with the award of two exploration blocks to Indian Oil and ONGC consortium under NELP-I. In 2003, Lanka IOC Pvt. Ltd. (LIOC) was launched in Sri Lanka. In 2005, Indian Oil's Mathura Refinery became the first refinery in India to attain the capability of producing entire quantity of Euro-III compliant diesel.
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Vocational Training Project Report
Page | 6
List of abbreviations used 1
MS
Motor Spirit
2
ATF
Aviation Turbine Fuel
3
SRN
Straight Run Naphtha
4
HSD
High Speed Diesel
5
IFO
Internal Furnace Oil
6
MTO
Mineral Turpentine Oil
7
MMTPA
Million Metric Tonnes Per Annum
8
FCCU
Fluidised Catalytic Cracking Unit
9
LOBS
Lube Oil Base Stocks
10
VDU
Vacuum Distillation Unit
11
CDU
Crude Distillation Unit
12
API
American Petroleum Institute
These are some of the abbreviations, several others have been used, however they have been clarified throughout the document.
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Overview of Haldia Refinery Haldia Refinery, one of the seven operating refineries of Indian Oil, was commissioned in January 1975. It is situated 136 km downstream of Kolkata in the district of Purba Midnapur, West Bengal, near the confluence of river Hooghly and Haldi. From an srcinal crude oil processing capacity of 2.5 MMTPA, the refinery is operating at a capacity of 5.8 MMTPA at present. Capacity of the refinery was increased to 2.75 MMTPA through de-bottlenecking in 1989-90. Refining capacity was further increased to 3.75 MMTPA in 1997 with the installation/commissioning of second Crude Distillation Unit of 1.0 MMTPA capacity. Petroleum products from this refinery are supplied mainly to eastern India through two product pipelines as well as through barges, tank wagons and tank trucks. Products like MS, HSD and Bitumen are exported from this refinery. Haldia Refinery is the only coastal refinery of the corporation and the lone lube flagship, apart from being the sole producer of Jute Batching Oil. Diesel Hydro Desulphurisation (DHDS) Unit was commissioned in 1999, for production of low Sulphur content (0.25% wt.) High Speed Diesel (HSD). With augmentation of this unit, refinery is producing BS-II and Euro-III equivalent HSD (part quantity) at present. Residue Fluidised Catalytic Cracking Unit (RFCCU) was commissioned in 2001 in order to increase the distillate yield of the refinery as well as to meet the growing demand of LPG, MS and HSD. Refinery also produces eco-friendly Bitumen emulsion and Microcrystalline Wax. A Catalytic De-Waxing Unit (CIDWU) was installed and commissioned in the year 2003 for production of high quality Lube Oil Base Stocks (LOBS), meeting the API Gr-II standard of LOBS. Finished products from this refinery cover both fuel oil products as well as lube oil products.
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Chapter 1
Mechanical Equipment
Page | 9
Mechanical Equipment The equipment present in the refinery may be broadly classified into the following groups: 1. Static Equipment 2. Rotary Equipment
Static Equipment: 1. Boilers 2. Furnaces 3. Heat Exchangers 4. Pipelines 5. Valves 6. Storage Tanks 7. Bearings
Rotary Equipment: 1. Pumps 2. Compressors 3. Turbines Some of these shall be looked upon in some detail in the following sections.
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Main Mechanical Components This section deals with the basic theoretical aspects of the major components in use in the refinery.
Pumps Pumps
Positive Displacement
Rotary
Dynamic
Reciprocating
External Gear
Lobe
Slide Vane
Internal Gear
Centrifugal
Special Effect
Figure 1: Classification of Pumps
A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. Pumps can be classified into three major groups according to the method they use to move the fluid: direct
lift, displacement,
and gravity pumps.
Pumps
operate
by
some
mechanism
(typically reciprocating or rotary), and consume energy to perform mechanical work by moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, come in many sizes, from microscopic for use in medical applications to large industrial pumps. Mechanical pumps serve in a wide range of applications such as pumping water from
wells, aquarium
cooling and fuel
filtering, pond
injection,
in
filtering and aeration,
the energy
in
industry for pumping
the car
industry for water-
oil and natural
gas or
for
operating cooling towers, etcetera. Most pumps used in the refinery are of the centrifugal type and hence they shall be elaborated upon.
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Working Principle of Centrifugal Pumps
Figure 2: Exploded View of Centrifugal Pump
The impeller of the centrifugal pump is rotated by a prime mover e.g. an electric motor, an engine or a turbine. According to Bernoulli’s principle, for an incompressible fluid, the sum of its pressure head, velocity head and gravitational head remains constant.
× + 2× +=() The impeller imparts a velocity to the incompressible fluid flowing through the pump thereby increasing the velocity head of the fluid. Now the fluid enters a volute casing wherein the area of cross section of the casing keeps increasing, by equation of continuity:
= Thus,
<
, hence
<
Since the total head must remain constant and at the same datum level,
cannot vary, which means
that the pressure head at the outlet must increase to keep the total head constant. This increase in pressure head ultimately translates to the manometric head of the pump.
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Compressors COMPRESSOR
POSITIVE DISPLACEMENT
DYNAMIC
RECIPROCATING
SINGLE ACTING
DIAPHRAGM
AXIAL
ROTARY
DOUBLE ACTING
LOBE
LIQUIDRING
SCREW
SCROLL
CENTRIFUGAL
VANE
Figure 3: Classification of Compressors
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed.
Figure 4: A reciprocating compressor Page | 13
Working Principle of Compressors The main type of compressor used in the refinery is reciprocating and hence the working principle of this type of compressor shall be elaborated upon. The reciprocating type compressor consists of a piston which is enclosed within the cylinder and equipped with suction and discharge valves. The piston receives power from main shaft through crankshaft and connecting rod. A flywheel/belt wheel is fitted on the crankshaft which is driven by electric motor or diesel engine. It supplies uniform power throughout the cycle of operations. The compression of gas is done by first drawing a volume of gas into its cylinder through suction valves during suction stroke by the piston and then compressing and discharging it on the return stroke of the piston through delivery valves. It s hould be not ed that rec iproc ating co mpre s s ors dis pla cemen t
are
posi tiv e
ma chin e s ,
wh ic h
me ans that i f ther e is no backpressure in the system, no c ompre s s ion
effect
s ha ll
be
obse rved.
Multistaging in Compressors Double
stage
or
two
stage reciprocating
compressor consists of two cylinders. One is called low pressure
cylinder
and
another
is
called
high pressure cylinder. When piston in low pressure cylinder is at its Outer Dead Centre (ODC) the weight of gas inside cylinder is zero (neglecting clearance volume), as piston moves towards Inner Dead Centre (IDC) pressure
falls
below
atmospheric
pressure
and suction valve opens due to pressure difference. The Figure 5: Multistaging in Compressors
fresh gas is drawn inside the low-pressure cylinder Page | 14
through suction filter. This gas is further compressed by piston and pressure inside and outside the cylinder becomes equal, at this point suction valve is closed. As piston moves towards ODC compression of gas takes place and when the pressure of gas is in range of 1.5 kg/cm2 to 2.5 kg/cm2 delivery valves opens and this compressed gas then enters into high pressure cylinder through inter cooler. This called as lowpressure compression. The intercooler reduces
the
temperature
of
the
compressed gas to the isothermal ambient temperature before allowing the gas to enter the high-pressure cylinder. This ends up saving a lot of work as can be seen from the diagram above. Similarly, there can be three-stage compressor, fourstage compressor or multiple-stage compressors. The more the number of stages, more is the operating curve similarity to the isothermal curve and hence greater is the efficiency.
Mathematically, work done by a compressor:
− − 4 5 = 1 [ 1 ]+ 1 44 [ 1 4 ] Sundyne Pumps Sundyne Pumps are special pumps that are designed to be operated at very high speeds. The pumps
are
usually
arranged
in
a
vertical
configuration. This kind of pumps make use of a gearbox which increases the rotation speed of the pump impeller to about 5 times that of motor speed. The approximate speed of operation of the pump is around 22000 RPM. The fluid enters the pump from one side, is struck by the impeller and is forced out Figure 6: Sundyne Pump
of the other side. Page | 15
Sundyne centrifugal pumps and compressors are traditionally utilized for processes requiring highhead (pumps: 6,300 ft-1,921m), and low-flow (pumps: 1,100 gpm or 250 m³/h). They are engineered and built to meet the Best Efficiency Point 'BEP' for production processes.
Valves A valve is a device for regulating or isolating the flow of gases, liquids, and slurries through pipework and launder systems. The force required to operate a valve can be carried out either manually or mechanically. Mechanical attachments called actuators to a valve are usually either electrically or pneumatically operated.
Common Types of Valves: 1. Ball 2. Butterfly 3. Gate 4. Diaphragm 5. Non-Return/Check 6. Globe 7. Pinch 8. Pressure Relief
Gate Valves Often simply called Gate valves, the valves are also used as isolation valves. They work simply by virtue of a gate which can be raised or lowered to allow or restrict the flow. Gate valves should not normally be used in a restrictive role i.e. partially open or partially closed condition, this is because it leads to rapid wearing of the base of the gate. Figure 7: Gate Valves Page | 16
Check Valves / Non - Return Valves A check valve
is a valve that normally allows fluid (liquid or gas) to flow through it in only one
direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various types of check valves used in
a
wide
variety
of
applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs,
Figure 8: Check Valve
check valves generally are very small, simple, or inexpensive. Check valves work automatically and most are not controlled by a person or any Figure 9: Sectionalised View of Check Valve
external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are
made of plastic or metal. An important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. Typically, the check valve is designed for and can therefore be specified for a specific cracking pressure.
Globe Valves A globe valve is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body. Globe valves are named for their spherical body shape with the two halves
of
the
body
being separated by an internal baffle. This has an opening that forms a seat
onto
which
a
movable plug can be Figure 10: Globe Valve
screwed in to close (or
shut) the valve. The plug is also called a disk. In globe valves, the plug is connected to a stem which Page | 17
is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.
Butterfly Valves A butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disk that rotates. The disc is positioned in the centre of the pipe. A rod passes through the disc to an actuator on the outside of the valve. Rotating the actuator turns the disc either parallel or perpendicular to the flow. Unlike a ball valve, the disc is always present within the flow, so it induces a pressure drop, even when open.
Figure 11: Butterfly Valve
Diaphragm Valves Diaphragm valves (or membrane valves) consists of a valve body with two or more ports, a diaphragm, and a "weir or saddle" or seat upon which the diaphragm closes the valve. The valve is constructed from either plastic or metal. There are two main categories of diaphragm valves: one type seals over a "weir" (saddle) and the other (sometimes called a "full bore or straight-way" valve) seals over a seat. The weir or saddle type is the most common in process applications and the seat-type is more commonly used in slurry applications to reduce blocking issues but exists also as a process valve. While diaphragm valves Figure 12: Diaphragm Valve
usually come in two-port forms (2/2-way diaphragm valve), they can also come with three ports (3/2-way
diaphragm valves also called T-valves) and more (so called block-valves). When more than three ports are included, they generally require more than one diaphragm seat; however, special dual actuators can handle more ports with one membrane. Diaphragm valves can be manual or
Page | 18
automated. Their application is generally as shut-off valves in process systems within the industrial, food and beverage, pharmaceutical and biotech industries. For the sake of conciseness, other valves are not elaborated upon.
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Unit Overview The main units of the Haldia refinery that were covered during the training period were: 1. Workshop 2. Fuel Oil Block (FOB) 3. Thermal Power Station (TPS) 4. Lube Oil Block (LOB) 5. Oil Movement and Storage (OM&S) 6. Diesel Hydro De-Sulphurisation (DHDS) 7. Effluent Treatment Plant (ETP) 8. Once-through Hydro-Cracker Unit (OHCU) 9. Garage During the training period, the basic mechanical activities relating to the above units were looked at.
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Haldia Refinery Plot Plan
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Chapter 2
Workshop
Page | 22
Figure 13: A lathe similar in size to the one available at the workshop
The Workshop is the heart of all mechanical maintenance at the IOCL Refinery at Haldia. Responsible for refurbishing and maintenance of the myriad pumps, valves, compressors, etcetera it is an important asset the plant cannot do without. The workshop features a variety of equipment such as large lathes, milling and planing machines, sand blasting chamber, and etcetera.
Some of the important machines undergoing maintenance at the workshop at the time of visit are elaborated in the following pages.
Centrifugal Pump
Centrifugal pumps are a sub-class of dynamic axisymmetric work-absorbing turbo machinery. Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. In the typical case, the fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from where it exits. Common uses include water, sewage, petroleum and petrochemical Page | 23
pumping. The reverse function of the centrifugal pump is a water turbine converting potential energy of water pressure into mechanical rotational energy, this principle is often used in pumped storage hydroelectricity projects.
Figure 14: Parts of a Centrifugal Pump
Like most pumps, a centrifugal pump converts mechanical energy from a motor to energy of a moving fluid. A portion of the energy goes into kinetic energy of the fluid motion, and some into potential energy, represented by fluid pressure (Hydraulic head) or by lifting the fluid, against gravity, to a higher altitude. The transfer of energy from the mechanical rotation of the impeller to the motion and pressure of the fluid is usually described in terms of centrifugal force, especially in older sources written before the modern concept of centrifugal force as a fictitious force in a rotating reference frame was well articulated. The concept of centrifugal force is not actually required to describe the action of the centrifugal pump. The outlet pressure is a reflection of the pressure that applies the centripetal force that curves the path of the water to move circularly inside the pump. On the other hand, the statement that the "outward force generated within the wheel is to be understood as being produced entirely by the medium of centrifugal force" is best understood in terms of centrifugal force as a fictional force in the frame of reference of the rotating impeller; the actual forces on the water are inward, or centripetal, since that is the direction of force need to make the water move in circles. This force is supplied by a pressure gradient that is set up by the rotation, where the pressure at the outside, at the wall of the volute, can be taken as a reactive centrifugal force. This was typical of nineteenth and early twentieth century writings, mixing the concepts of centrifugal force in informal descriptions of effects, such as those in the centrifugal pump. Page | 24
Vertical Turbine Pump A specialized centrifugal pump designed to move water from a well or reservoir that is deep underground. Also, known a deep well turbine pump or a line shaft turbine pump, it is one of two main types of turbine pumps. The two main types of turbine pumps are vertical turbine pumps and submersible turbine pumps. While submersible pumps have the electric motor located underwater at the bottom of the pump, vertical turbine pumps have the motor located above ground, connected via a long vertical shaft to impellers at the bottom of the pump. The term “turbine” in the pump name is somewhat of a misnomer, as this pump type has nothing to do with a turbine.
Figure 15: Vertical Turbine Pump
The pump under discussion needed replacement of a few parts and also needed an anti-rust treatment.
Heat Exchangers A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage Page | 25
treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant. Heat Exchangers need to be retubed from time to time because at times corrosion sets in due to the temperature and type of fluid flowing through the tubes of the heat exchanger. Also, tubes might be clogged which results in lower flow and efficiency.
Figure 16: Internal tubing of a heat exchanger
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Chapter 3
Fuel Oil Block
Page | 27
This Unit was commissioned in August 1974, srcinally designed for processing light Iranian Aghajari crude but presently crudes like Arab mix (lube bearing) and Dubai crude (non – lube bearing) are processed. The capacity has been increased from 2.5 MMPTA to 4.6 MMPTA. The Fuel Oil Block is primarily meant for the production of Fuel Oil, of prime importance to Mechanical Engineers, this unit has several compressors and pumps, both of positive and non-positive displacement types.
A very important part of a centrifugal and thereby all pumps was elaborated upon in this block. The part under discussion is a mechanical seal which assumes prime importance in the oil industry because of the hazardous materials being processed. Before going to the nuances of this block, the basic concepts of a Mechanical Seal shall be elaborated upon.
Mechanical Seal A mechanical seal is a device that helps join systems or mechanisms together by preventing leakage (e.g. in a plumbing system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets.
Single Mechanical Seal A
single
mechanical
seal
consists
of
two
very flat surfaces that are pressed together by a spring and slide against each other. Between these two surfaces is a fluid film generated by the pumped product. This fluid film prevents the mechanical seal from touching the stationary ring. An absence of this fluid film (dry running of the pump) results in frictional heat and ultimate
destruction
of
the
mechanical
seal. Mechanical seals tend to leak a vapor from the Figure 17: Mechanical Seal
high-pressure side to the low-pressure side. This fluid
lubricates the seal faces and absorbs the heat generated from the associated friction, which crosses the seal faces as a liquid and vaporizes into the atmosphere. So, it's common practice to use a single mechanical seal if the pumped product poses little to no risk to the environment.
Page | 28
Double Mechanical Seal A double mechanical seal consists of two seals arranged in a series. The inboard, or primary seal keeps the product contained within the pump housing. The outboard, or secondary seal prevents the flush liquid from leaking into the atmosphere. Double mechanical seals are offered in two arrangements:
Back to back Two rotating seal rings are arranged facing away from each other. The lubricating film is generated by the barrier fluid. This arrangement is commonly found in the chemical industry. In case of leakage, the barrier liquid penetrates the product and this can be detected with the help of an appropriate sensor.
Face to face The spring loaded rotary seal faces are arranged face to face and slide from the opposite direction to one or two stationary seal parts. This is a popular choice for the food industry, particularly for products which tend to stick. In case of leakage, the barrier liquid penetrates the product. If the product is considered hot, the barrier liquid acts as a cooling agent for the mechanical seal. Double mechanical seals are commonly used in the following circumstances: 1.
If the fluid and its vapours are hazardous to the operator or environment, and must be contained.
2.
When aggressive media are used at high pressures or temperatures
3.
For many polymerising and sticky media
The seal demonstrated was a double mechanical seal.
Units of the Fuel Oil Block has been dealt with in the following section.
Page | 29
Units of the Fuel Oil Block The fuel oil block comprises the following units: 1.
Crude Distillation Unit – I (Unit 11)
2.
Crude Distillation Unit – II (Unit 16)
3.
Naphtha Hydrotreating Unit (Unit 21)
4.
Catalytic Reforming Unit (Unit 22)
5.
Kero-Hydro De-Sulphurisation Unit (Unit 23)
Basic parameters of these units are featured below.
Brief description of the FOB Units: Crud e Dis tilla tion U ni t – 1
P urpose :
Fe ed:
P roducts: Un it Capa cit y
To distil the crude oil under atmospheric pressure for producing multi-component distillates and send them to OM&S for supply. Crude Oil from various offsite tanks via booster pumps Propane, LPG, Naphtha, Kerosene, Aviation Turbine Fuel, Diesel, Reduced Crude Oil, Jute Batching Oil. 510 m3/h
Crud e Dis tilla tion U ni t – 2
P urpose :
Fe ed:
P roducts: Un it Capa cit y
To distil the crude oil under atmospheric pressure for producing multi-component distillates and send them to OM&S for supply. Crude Oil from various offsite tanks via booster pumps Propane, LPG, Naphtha, Kerosene, Aviation Turbine Fuel, Diesel, Reduced Crude Oil, Jute Batching Oil. 615 m3/h
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Napht ha H ydrot reati ng U nit
P urpose :
To remove Sulphur from straight run Naphtha which would otherwise lead to considerable environmental pollution.
Fe ed:
Heavy straight run Naphtha from offsite storage tanks.
P roducts:
De-Sulphurised Naphtha (DSN)
Un it Capa cit y
216 MTPA
Cata lyt ic Re form i ng Un it
P urpose :
Fe ed:
P roducts: Un it Capa cit y
Transform the low octane constituents into high octane rating aromatics in the range of 6 to 10 Carbon atoms. De-Sulphurised Naphtha (DSN)
Reformate
216 MTPA
Kero -Hyd ro De -S ulph uris ation U nit
P urpose :
To remove Sulphur from three raw kerosene distillate cuts produced from Atmospheric Distillation Units.
Fe ed:
Raw Kerosene, ATF, MTO from CDU
P roducts:
De-Sulphurised Kerosene, ATF, MTO
Un it Capa cit y
500 MTPA
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Chapter 4
Thermal Power Station
Page | 32
TPS is one of the two main wings of power in Haldia refinery of Indian Oil Corporation Limited (IOCL). It is called customarily called CPP – I . The power unit called CPP – II is a gas turbine powered unit. CPP mea ns Captiv e Power P lan t because both these units together supply the total power required by the different units of the plants and also, the IOCL Township nearby.
Only CPP – I was in the scope of the training.
Capacity of TPS There are four steam turbines with four boilers for generating steam. Boilers I, II and III are made by BH E L. Each of them is capable of delivering 125 tons of superheated steam per hour. The fourth boiler (Boiler IV) with a capacity of 150 tons of steam per hour is made by ABB. Four steam turbines are there which have been manufactured by BHEL each having a connectivity with all the boilers. The steam turbines act as the prime movers of four turbo generators rotating at 3000 rpm. Three of them (TG-1, TG-2, TG-3) have individual capacity of 10.5 MW and the fourth one (TG4) have a capacity of 16.5 MW. TG-4 is the most recently installed generator and its excitation system is an AC excitation system (Brushless exciter using rotating diode rectifier). The first three generators are excited by DC exciter (using two DC generator) systems.
The main components of the Thermal Power Station are:
Cooling Towers A cooling tower is a semi enclosed device for evaporative cooling of cooling water coming out from the condenser with the help of unsaturated water. So, in this process, proper mixing with hot water droplet and air will take place. There will be both heat and mass transfer for getting more efficient cooling in the cooling tower. Usually the structure of cooling tower may be done by wood, concrete, steel etc. Corrugated surfaces or perforated trays can be provided inside the tower for uniform distribution of water droplets and better atomization of the water inside the tower. The air is allowed to flow from the bottom of the tower or perpendicular to the direction of the water flow (in crossed flow cooling tower) and the exhausts is allowed to go out to the atmosphere after effective cooling.
Demineralisation Plant (DM)
Page | 33
Here the water is treated for removing the minerals and radicals so that it does not create erosion problems when heated in the boiler drum. The pH of the water is tested and then it is monitored and kept nearly at 7 by adding sufficient acidic or basic materials. From here the water is sent to a surge tank which stores the water coming from different units and then sends the water to de-aerator by the help of a pump. The water level in the surge tank is controlled by a level switch and PLC system.
Deaerator One of the feed water heaters is a contact-type open heater, known as deaerator, others being closed heaters. It is used for the purpose of de-aerating the feed water. The presence of dissolved gases like oxygen and carbon dioxide in water makes the water corrosive, as they react with the metal to form iron oxide. The solubility of these gases in water decreases with increase in temperature and becomes zero at the boiling or saturation temperature. These gases are removed in the de-aerator, where feed water is heated to saturation temperature by the steam extracted by the turbine. Feed water after passing through a heat exchanger is sprayed from the top so as to expose large surface area, and the bled steam from the turbine is fed from the bottom. By contact the steam condenses and the feed water is heated to the saturation temperature. Dissolved oxygen and carbon dioxide gases get released from the water and leave along with some vapour, which is condensed Figure 18: Deaerator
back to the vent condenser, and the gases are vented out. To neutralize the
effect of the residual dissolved oxygen and carbon dioxide gases in water, s odium s ulphit e or hy dra zine is injected in suitable calculated doses into the feed water at the suction of the boiler f eed
pump. The de-aerator is usually placed near the middle of the feed water system so that the total pressure difference between the condenser and the boiler is shared equitably between the condenser pump and the boiler feed pump. The feed water heaters before the de-aerator are often termed as high -pre s s ure heat ers and those after the de-aerator
are open
are termed as low-
pre s s ure he aters . There are two de-aerators that supply water to the four boilers of the thermal
power station.
Page | 34
Boiler In TPS, four boilers are in operation and are used for steam generation. A steam generator generates steam at a desired rate at a desired pressure and temperature by burning fuel at its furnace. A steam generator is a complex integration of furnace, super heater, economizer, reheater, boiler or evaporator, and air preheater along with various auxiliary such as ash handling equipment, pulverisers, burners, fans, stokers, dust collectors and precipitators. The boiler is that part of steam generator where phase change occurs from liquid to vapour essentially at constant pressure and temperature. However, the term “boiler” is traditionally used to mean the whole steam generator. The steam coming out from the boiler is treated again to maintain its pressure (61 kg/cm 2) and temperature (450°C) and made oxygen free. This is called high pressure s up erhe ated or VH S tea m which is sent to turbine generator for generating electricity. This is also converted to medium pressure
•
•
•
or VM S team and low pres s ure or VB S team for other uses as follows:
VH S team: Used in turbine generator as well as in burner
VM S team: Used in heat exchangers in the different units VB S team: Used as cleaning agent
Page | 35
Figure 19: Boiler
Burner Unit Here furnace oil is burnt in presence of air to produce hot flue gas at very high temperature. Every boiler has six burner units. Furnace oil is burnt and the hot gas is released in the boiler. The relatively cold flue gas after going through the economizer zone is sent out to stack and released in the atmosphere.
Air Supply An air supply unit is kept to supply air to the compressor as well as drier to produce compressed dry air supply for pneumatic instruments.
Steam Turbine The TPS or CPP-I has four steam turbines. Each turbine has two sections, namely HP and LP section. The inlet blades (at HP section) are impulse type and the outlet blades are reaction (at LP section) type. The steam produced in the boiler is fed to the inlet section at very high pressure (6062 Kg/Sq. cm) which rotates the inlet blades. As the steam moves from HP to LP region, its temperature decreases and the low-pressure steam (14 Kg/Sq. cm) is extracted from a set point determined previously. The exhaust steam is fed to the condenser.
Air Drier Page | 36
A compressed air dryer is a device for removing water vapour from compressed air. Compressed air dryers are commonly found in a wide range of industrial and commercial facilities. The process of air compression concentrates atmospheric contaminants, including water vapour. This raises the dew point of the compressed air relative to free atmospheric air and leads to condensation within pipes as the compressed air cools downstream of the compressor. Excessive water in compressed air, in either the liquid or vapour phase, can cause a variety of operational problems for users of compressed air. These include freezing of outdoor air lines, corrosion in piping and equipment, malfunctioning of pneumatic process control instruments, fouling of processes and products, and more. There are various types of compressed air dryers. Their performance characteristics are typically defined by the dew point.
Specifications
Boiler Feed Pump Capa cit y: 145 m3/h. Lube Oi l s pe c ific gra vity: 0.57 Dis char ge P res s ure: 80-85 Kg/cm2
Motor Data for Boiler Feed Pump Capa cit y: 460 KW
Speed: 2980 RPM
FD Fans Type: Radial single inlet and single width Page | 37
Medium: Air Des igne d r ating : 40.8 m3/sec Fa n S peed: 740 RPM Capa cit y: 2400 nm3/h.
Air Dryer Mois t air in l et: RH 100% Pressure:
8 kg/cm2 (normal), 6.5 kg/cm2 (minimum)
Te mpe ratur e: 40°C Type o f Des ic can t: Activated Alumina P res s ure drop ac ros s the dr ie r: 0.5 kg/cm2 (Maximum)
Figure 20: Schematic Diagram of CPP - I
Adsorption Towers Page | 38
Des ign P res s ure: 12 kg/cm2
Pre-filter and After-filter Filte r e lem e nt: Polypropylene Des ign P ress ure: 12 kg/cm2
Cooler: Water flow: 22.825 m3/h. Water Pressure:
4kg/cm2
Inle t wa ter tempe rature: 33°C Outle t wa ter temp erature: 37°C
Heater: P ower rati ng: 81KW (56.7 KW and 24.3KW)
Page | 39
Chapter 4
Lube Oil Block
Page | 40
In lube oil block, the reduced crude oil from the Atmospheric Distillation Unit (ADU) is processed to produce lube base stock, slack wax, transfer oil feed stock (TOFS), etc. LOB contains the following 8 units:
1. Vacuum Distillation Unit (Unit 31) 2. Propane De-Asphalting Unit (Unit 32) 3. Furfural Extraction Unit (Unit 33) 4. Solvent De-Waxing Unit (Unit 34) 5. Hydro Finishing Unit (Unit 35) 6. Bitumen treatment Unit (Unit 36) 7. Visbreaking Unit (Unit 37) 8. N – Methyl Pyrrolidine (NMP) Extraction Unit (Unit 38) 9. Micro Crystalline Wax Unit (Unit 39) 10. Catalytic Iso De-Waxing Unit (Unit 84)
Un it 3 1: Vac uum Dis tillati on U nit
Main fe ed: RCO
RCO (400°C) •
Gas oil
•
Spindle oil
•
Light oil
•
Intermediate oil
•
Heavy oil
•
Short residue (360°C)
Un it 3 2: P ropa ne De -As phal ting U nit
Main fe ed: Short Residue
Treated with propane (225°C)
→
DAO (De asphalt oil) + Asphalt (Bitumen)
Un it 3 3: F urfu ral E xtr ac tion U nit
Page | 41
Main Fe ed: L.O./I.O./H.O./DAO.
feed to Unit 34 (De-waxing Unit)
→→
(by furfural extraction) (225°C) In/Hn/Bn/De-waxed lube oil
→
Raffinate + Extract Raffinate
Unit 3 5: Hy dro Fini s hing Unit
Main Fe ed: Lube Oil (de-waxed)
→
Heated in catalytic bed at 250°C
→
Finished Lube Oil
Unit 3 7: Vis br eakin g Unit
Main Fe ed: Asphalt + SR (60:40) •
Gasoline (mixed in petrol)
•
Gas oil
•
VB tar (FO)
→
(heated to 450°C)
Un it 3 8: N MP Unit
Main Fe ed: I.O./H.O./DAO.
→
treatment with NMP solution
Un it 3 9: M ic roc rys tall ine Wax Un it
After de waxing in Unit 34 Residue wax is treated in this unit by Hydrogen to produce Microcrystalline wax.
Un it 8 4: C atal ytic Is o De -Waxin g Unit
Raffinate (from Units 33 and 38) + Wax Sulphur/Nitrogen/ H2S/ NH3
→
treatment in catalytic bed with Hydrogen to remove
Temperature: 310°C – 380°C
P roduct: De-Waxed Lube Oil.
The Block Diagram of the Lube Oil Block has been presented in the next page.
Page | 42
Figure 21: Block Diagram of Lube Oil Block
Several reciprocating compressors are in operation in this block and they present a mechanical engineer with a great opportunity to learn and observe the working principles of the system. The particular compressor that was covered during the visit was a 3 s tage , 4-cylind er re c iproc ating ma keu p g as c ompre s s or. S tage 1: 2 cylinders
S uc tion Pr ess ure : 1.5 kg/cm2
Dis ch arg e P ress ure: 4.5 kg/cm2
S tage 2: 1 cylinder
S uc tion P res s ure : 4.5 kg/cm
Dis ch arg e P ress ure: 8.5 kg/cm
S tage 3: 1 cylinder
S uc tion Pr ess ure : 8.5 kg/cm2
Dis ch arg e P ress ure: 12 kg/cm2
2
2
The makeup gas entered the compressor at a temperature of about 45°C, after compression in the first stage, the temperature rose to around 130°C and pressure rose to around 4.5 kg/cm 2, this gas was passed through an intercooler which cooled the compressed gas to srcinal temperature of 45°C. After this, the gas was passed through the second stage, where the temperature rose to around 140°C and pressure rose to around 8.5 kg/cm2, this gas was again passed through another Page | 43
intercooler which brought the temperature down to 45°C. Finally, the gas was passed through the last stage and was compressed to around 12 kg/cm 2 pressure and the temperature of the gas at this point was around 130°C, at this stage the gas was discharged through an air receiver for required applications.
Page | 44
Chapter 5
Oil Movement & Storage
Page | 45
This section of the plant deals with the logistical challenge of moving crude oil to the plant for refining and also distributing the refined products to consumers. There are several storage tanks which maintain a large inventory of crude oil and finished products like Aviation Turbine Fuel, Motor Spirit, Bitumen, Diesel, etcetera. Apart from several storage tanks, this unit has the following main sections: 1. Wagon Loading Gantry 2. Truck and Tank Loading station 3. Bitumen Filling Station
Tank and Truck Loading station
Figure 22: TTL Station
The tank and truck loading station consists of four tee n point s through which different products are filled in trucks. The trucks generally consist of three chamb e rs . The products are pumped through the pipes and the PDM (positive displacement meter) measures the flow rate. There is also a liquid Page | 46
controller which removes the liquid vapour (if any). Different products like A TF (Av iati on Turbine Fuel ), MS (Motor S piri t), MTO (Mine ral Turpentine Oil) , S KO (Super Keros ene Oil) , HS D (High S peed D i esel) , J BO (J ute Batc hing Oi l), FO (F urn ace Oil ), CB FS (C arbon Bl ack F e ed S tock ) and M ic roc rys tall ine Wax are filled in this station. Ope rati on:
The trucks are weighed and taken to the appropriate point where first the depth is checked using a dipstick. There is a terminal in the gantry which display the specification of loading to be done for example the number of chambers, capacity etc. After completion of loading the truck is weighed again. Subtraction of the tare weight and gross weight gives the net weight.
Wagon Loading Gantry The petroleum products (mainly MS, HSD etc.) are also dispatched to different parts of India through railway wagons. Ope rati on:
Two types of wagons are used in this purpose viz. General Purpose
and
(of capacity
BPD 64700
litres). A primary test is conducted leakage.
for Again,
body the
dipstick is calibrated with
the
theoretical
data. Initially 700 to 1000 litres of product is pumped in for leaktesting and then the tested
wagons
are
Figure 23: Wagon Loading Gantry
filled with the products.
Page | 47
Tanker Loading and Unloading Some portion of the finished products are also sent to consumers via ships, also, most of the crude oil processed at the plant is from the middle east and enters Indian shores via ships. Ships are loaded at the nearby Haldia port using ship loading gantries that are supplied by pipelines from the refinery. Some finished products such as MS, HSD, etcetera is also imported and the purpose of importing the latter two is that country wide demand of these two products is more than the amount produced in the refinery. Types & C a pa cit ies o f Tank ers : •
General Purpose (G.P.) series: Up to 25,000 tonnes.
•
Medium Capacity (M.C.) series: 25,000 tonnes to 45,000 tonnes.
•
Low Range (L.R.) series: Three sub-categories namely L.R-1, L.R-2, L.R-3. 45,000 tonnes to 1,20,000 tonnes.
•
Very Large Crude Carrier (V.L.C.C): 1,20,000 tonnes to 2,80,000 tons.
•
Ultra Large Crude Carrier (U.L.C.C.): 2,80,000 tonnes onwards. Vessels of these type do not come to Indian ports.
Per day requirement of Haldia Refinery is 17,000 tonnes of crude oil. Ope rati on:
Figure 24: Tanker Ship and Marine Loading Arm
A marine loading arm, also known as a mechanical loading arm is a mechanical arm consisting of articulated steel pipes is used that connects the tanker ship to the cargo terminal. Genericized Page | 48
trademarks such as Chiksan are often used to refer to marine loading arms. These arms allow movement and hence allow uninterrupted filling of the tanker ship during tide and ebb.
Bitumen Filling Station Bitumen, also known as Asphalt is a sticky, black and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product; it is a substance classed as a pitch. The bottom product of crude i.e. RCO (Reduced Crude Oil) is taken to a vacuum distillation unit where distillate lube is extracted. The bottom product obtain is SR (Short residue) which is mixed with solvent propane. Then it is taken to a de-asphalting unit where the asphalt is taken out which is black and hard having less penetration. There are three grades of bitumen: 1.
80/100
2.
60/70
3.
30/40
These are classified based on penetration property. A needle with the help of a reference weight is introduced inside the bitumen, and it dips the least amount for 30/40 and most for 80/100. The temperature of bitumen produced it around 140˚C. Its temperature is later brought down in the BCU (bitumen cooing unit).
Drum fill ing
Weight of dry drum = 8 kg. (Approximate.) Weight of filled drum = 156.5 kg. (Approximate.) Empty drum is unloaded from truck and taken to a filling system by belt conveyers. The system comprises of a pipeline through which the bitumen flows to the drum. There is a twin arm and jack system to hold the drum upward for good contact with the filling tube. The mouth of the filled drum is sealed with a cap using pneumatic pressure. It’s then taken to digester where at a time 16 drums are digested (8 on each side). The fork lifter then takes the drum and stacked at a place. Then they are dispatched to different places by truck or railway wagon. Trucks are taken to the bitumen gantry and loaded. There are four such points for bitumen filling.
Page | 49
Tanks
Almost one-third of the refinery area is allocated for different types of tanks. They are designed according to the needs of the product conservation like in the case of Motor Spirit or Straight Run Naphtha there must be a provision to reduce the pressure produced due to the vaporisation of these products and hence these are generally stored in floating roof tanks. By design they are four types:
1.
Fix ed r oof tank : Meant for liquids with very high flash points, (e.g. fuel oil, water, bitumen
etc.) Further classifications are: •
Co ne R oof Ta nk
•
Do me Ro of T a nk : Dome roof tanks are meant for tanks having slightly higher storage
pressure than that of atmosphere (e.g. slop oil). •
2.
Umbrel la Roof Ta nk
Floa ting roof tank : •
E xte rna l Floa ting Ro of ( F R) Ta nk : FR tanks do not have a fixed roof (it is open in
the top) and has a floating roof only. Medium flash point liquids such as naphtha, kerosene, diesel, and crude oil are stored in these tanks. •
Inter na l Floa ting Ro of (IFR ) Ta nk : IFR tanks are used for liquids with low flash-points
(e.g., ATF, MS. gasoline, ethanol). These tanks are nothing but cone roof tanks with a floating roof inside which travels up and down along with the liquid level. This floating roof traps the vapor from low flash-point fuels. Floating roofs are supported with legs or cables on which they rest.
Although there are variations in design, there are some basic components that a tank is provided with:
1.
Manhole on the shell and roof.
2.
Product inlet and outlet nozzle.
3.
Drains.
4.
Staircase and ladder.
5.
Mechanical type level gauge. Page | 50
6.
Open vane with wire mesh / Breather valve / Vent with flame arrestor depending on the type of substance being stored.
7.
Sampling device.
8.
Temperature gauge.
9.
Jet mixing nozzle.
10.
Inert gas blanketing.
11.
Steam heating coils if the substance to be stored has a tendency to solidify e.g. bitumen.
Product is taken to this tank though the inlet by different pumps. There are two outlets one for blending and product conveying and another for drainage. Generally, products from the different units also contain some amount of water with them. This unwanted water is drained through the drainage outlet. During blending different products are mixed to meet the specifications of the final product such as Motor Speed (MS), Diesel etc. Constant circulation of the product of tank is done for better mixing through these outlets.
Cathodic Protection
External protection of Mounded LPG storage bullets is an electrochemical phenomenon. The control of this common process can be achieved by employing cathodic protection system. The state of art cathodic system can be implemented to distribute uniform current over the entire surface to be protected to achieve uniform corrosion protective potentials. Types
Permanent Impressed Current type of cathodic protection system using continuous anode system is to be implemented for protecting external surface area of bullet against corrosion.
P rotec tiv e Curre nt Dens ity
Protective current density recommended by LURGI. Page | 51
General specification and BIS 8062-Part1 (1976) are as follows: •
Bare steel
25 mA/m2
•
Painted steel
2.5 mA/m2
Protective current density of 25 mA/m2 of bare steel exposed to sand shall be adequate to achieve desired protection level at an operating temperature of 5°C - 46°C. P rotec tion C rite ria
The protected bullet to soil potential test has been established as a standard measure technique for evaluation of corrosion protective potential. The OFF potential window considered is -0.85V (OFF) to -1.15V (OFF) measured with respect to Copper-Copper Sulphate reference electrode at an instant by interrupting the protective current and eliminating circuit IR drop.
Ty pe s of S urfac e Co ating/Pa inting
External surface of bullet is Polyurethane coated and buried in mound of sand layer.
Page | 52
Chapter 6
Diesel Hydro De-Sulphurisation Unit
Page | 53
Hydrodesulphurisation
(HDS)
is
a
catalytic
chemical process widely used to remove sulphur (S) from natural gas and from refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. The purpose of removing the sulphur, and creating products such as ultra-low-sulphur diesel, is to reduce the sulphur dioxide (SO2) emissions that result from using high Sulphur fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion. Another important reason for removing Sulphur from the naphtha streams within a petroleum refinery is that Sulphur, even in extremely low concentrations, poisons the noble metal catalysts (Platinum and Rhenium) in the catalytic reforming units that are subsequently used to upgrade the octane rating of the naphtha streams.
Figure 25: A distillation column
Page | 54
The industrial Hydrodesulphurisation processes include facilities for the capture and removal of the resulting Hydrogen Sulphide (H2S) gas. In petroleum refineries, the Hydrogen Sulphide gas is then subsequently converted into by-product elemental Sulphur or Sulphuric Acid (H 2SO4). In fact, the vast majority of the 64,000,000 metric tons of Sulphur produced worldwide in 2005 was by-product Sulphur from refineries and other hydrocarbon processing plants.
In an industrial hydrodesulphurisation unit, such as in a refinery, the Hydrodesulphurisation reaction takes place in a fixed-bed reactor at elevated temperatures ranging from 300°C to 400 °C and elevated pressures ranging from 30 to 130 atmospheres of absolute pressure, typically in the presence of a catalyst consisting of an alumina base impregnated with Cobalt and Molybdenum (usually called a CoMo catalyst). Occasionally, a combination of nickel and molybdenum (called NiMo) is used, in addition to the CoMo catalyst, for specific difficult-to-treat feed stocks, such as those containing a high level of chemically bound nitrogen.
The main units of the DHDS Block are: Figure 26: Process Flow Diagram
1. Fluidised Catalytic Cracking Unit (Unit 17, 18, 19) 2. Hydrogen Unit (Unit 24) 3. Diesel Hydro De-Sulphurisation Unit (Unit 25) 4. Sour Water Stripping Unit (Unit 26) 5. Sulphur Recovery Unit – II (Unit 28) Page | 55
6. Amine Regeneration Unit (Unit 29) 7. Gas Turbine Generation Unit (Unit 58) 8. Heat Recovery Steam Generation Unit (Unit 59) 9. Cooling Water System (Unit 71) 10. Nitrogen Unit (Unit 73, 74) 11. Vacuum Distillation Unit (Unit 82) 12. Sulphur Recovery Unit – III (Unit 83) 13. Naphtha Hydro Treatment Unit (Unit 85)
Apart from these, during the visit a turbine operated blower, a turbine operated centrifugal compressor, stream ejectors in the distillation column and the sonic boom emerging from within them were also shown.
Page | 56
Chapter 7
Effluent Treatment Plant
Page | 57
The refinery generates several different types of waste that needs to be treated. Some common wastes are:
1.
Utility Wastes: Ash, Sludge, Dilute Aqueous Waste from cleaning activities
2.
Processing Wastes: Chlorides, Sulphides, Bicarbonates, Ammonia, Hydrocarbons, suspended solids.
3.
Hydro-Cracking Wastes: Ammonia, Hydrogen Sulphide, spent catalysts, metallic compounds.
4.
Fluidised Catalytic Cracking Wastes: Fine Catalyst particles.
5.
Coking Wastes: Slurry, Coke dust, Hydrocarbons.
6.
Alkylation and polymerisation wastes: Sludge from neutralisation, acidic solution.
These were just some of the wastes, several other kinds of waste are generated and the effluent needs to be treated so as to ensure that it does not harm the environment.
All the effluents from the refinery are subjected to a purification process in ETP. Hence, it is one of the important parts of the plant.
Operation
Figure 27: Flow Chart of ETP
Chemical effluents from all parts of the plant are generally taken to the new influent sump. Then they are treated physically, chemically and biologically to separate out the clean water and different effluents. The effluents are given with allowed a settling time and top layer consisting mainly of oil is taken out. In API bays the oil, water (with some amount of oil) and sludge is separated out using Page | 58
AP I Oi l-W ater S epa rat ors . An API oil–water separator is a device designed to separate gross
amounts of oil and suspended solids from the wastewater effluents of oil refineries, petrochemical plants, chemical plants, natural gas processing plants and other industrial oily water sources. The name is derived from the fact that such separators are designed according to standards published by the American Petroleum Institute (API). Equalization ponds give a high residence time for the sludge to settle down.
Figure 28: ETP
Lime solution, Ferrous Sulphate (also Hydrogen Peroxide for high sulphur content) is charged to clarify the water. Mechanically extra oxygen is mixed with this water in aeration tank by agitation to break down the organic impurity.
Oil Skimmers
Equipment that removes oil floating on the surface of a fluid. In general, oil skimmers work because they are made of materials to which oil is more likely to stick than the fluid it is floating on. Pretreating the fluid with oil skimmers reduces the overall cost of cleaning the liquid.
All designs depend on the laws of gravity and on surface tension in order to function. The six main types of oil skimmers are belt, disk, drum or barrel style, mop, large tube or mini tube, and floating suction oil skimmers.
Page | 59
Equalisation Tanks Equalisation tanks are provided:
(i)
To balance fluctuating flows or concentrations.
(ii)
To assist self-neutralisation.
(iii)
To even out the effect of a periodic "slug" discharge from a batch process.
Types of e qual is ation tanks :
•
Flo w through type: Useful in assisting self-neutralisation. A flow through type tank once
filled, gives output equal to input. •
Inter mittent flo w typ e: Flow balancing and self-neutralisation are both achieved by using
two tanks, intermittently one after another.
•
Vari a bl e inflo w/c on s tant dis cha rge type: When flows are large an equalization tank of
such a size may have to be provided that inflow can be variable while outflow is at a constant rate.
Trickling Filters Also called trickle filter, trickling biofilter, biological filter and biological trickling filter roughing filters, intermittent filters, packed media bed filters, alternative septic systems, percolating filters, attached growth processes, and fixed film processes. Consists of a fixed bed of rocks, lava, coke, gravel, slag, polyurethane foam, peat moss, ceramic, or plastic media over which sewage flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced air flowing through the bed or natural convection of air if the filter medium is porous.
Aeration Tank An aeration tank is a device in which liquid is held in order to increase the amount of air within it. There are two main methods of aerating liquid: forcing air through the liquid or forcing liquid through the air. The water is mixed with biological agents and then aerated. The increased oxygen promotes the growth of the beneficial biological material. That material will consume unwanted waste products
Page | 60
held in the water. The beneficial material will grow due to increased oxygen and food, which makes it easier to filter the water.
Lagoons / Basins Effluent Treatment Plants have lagoons / basins which are final polishing ponds.
Ty pe s of a erate d lag oons/ ba s ins :
•
S us pens ion Mix ed L agoon s : Suspension mixed lagoons, where there is sufficient energy
provided by the aeration equipment to keep the sludge in suspension.
•
Fa cul tativ e lago on s : There is insufficient energy provided by the aeration equipment to keep
the sludge in suspension and solids settle to the lagoon floor. The biodegradable solids in the settled sludge then degrade anaerobically.
National Standards The treated water must have maximum limits of the following:
•
Biological Oxygen Demand (BOD):
25 mg/l (30-day average) 45 mg/l (07-day average)
•
Total Suspended Solids (TSS)
30 mg/l (30-day average) 45 mg/l (07-day average)
•
pH shall remain between 6 and 9.
There shall be no visible solids or oil.
Page | 61
Chapter 7
Once-through Hydro Cracking Unit
Page | 62
It consists of Hydrogen Generation Unit, Once-through Hydrocracker Unit, Sulphur Recovery Unit and Nitrogen Unit. Initially installed with a 2.5 MMTP A crude processing capacity with designed Lube Oil Base Stocks, the Refinery has subsequently augmented its capacity to process 6.0 MMTP A crude. The capacity of the refinery is being augmented to 7.5 M MTP A through revamp of Crud e Dis tilla tion Un it in the year 2009-10. Since commissioning of the P aradi p -Hal dia Cr ude Oil P ipe line ( PHC P L) in Jan'09, the refinery started receiving crude oil fr om Paradip port and receiving
of crude by oil tankers through oil jetties has come down resulting in optimization of transportation costs of crude oil. The Refinery has facilities for storage of crude oil and finished products produced by the refinery. Hydro Cracking Unit is designed for 1.2 MMT/yea r (165.6 m³ /hr, 25,000BP S D). The objective of the Hydro Cracking Unit is to produce middle distillate fuel of superior quality. The unit is designed to process two different types of feed i.e. Arab M ix HV G O, Bo mba y High HVGO . All the H2S is removed by absorbing in DEA.
Process Description Heavier Hydro-Carbon molecules are mixed with Hydrogen and the mixture is subjected to severe operating conditions of Temp. (380-400°C) and pressure (165 – 185 kg/cm 2) to get Lighter HydroCarbons like LPG, MS & HSD components. Strict operating conditions are maintained to get specified products. All products are of Superior quality w.r.t. Sulphur content. The Hydrocracker Unit consists of four principle sections: Make-Up Gas Hydrogen Compression •
•
Reactor Section
•
Fractionation Section
•
Light Ends Recovery Section
Reactor Feed System Fresh feed to the Hydrocracker consists of a blend of Arab Mix and Bombay High VGO. The feed control system allows the operator to control the ratio of Arab Mix and Bombay High VGOs in order to set the relative rates of each. The preheated and filtered oil feed is combined with a preheated mixture of makeup hydrogen from the make-up hydrogen compression section and hydrogen-rich recycle gas from the recycle gas compressor in a gas-to-oil ratio of 845 Nm 3/m3. The reactor system contains one reaction stage consisting of two reactors in series in a single high-pressure loop. The lead and main reactors contain hydro treating and hydro cracking catalyst (Si/Al with Ni-Co-Fe) for denitrification, desulphurization, and conversion of the raw feed to products. The reactor effluent is initially cooled by heat exchange with the VGO feed and then by heat exchange with recycle gas and with the product fractionators feed. The effluent is then used to generate medium pressure [12.0 kg/cm2 (g)] steam. Page | 63
Fractionation Section The fractionation section consisting of the fractionators, side cut strippers, and heat exchange equipment is designed to separate conversion products from unconverted feed. The reaction products recovered from the column are Sour Gas (Off gas), Unstable Light Naphtha, Heavy Naphtha, Kerosene, Diesel and FCC Feed. The fractionator off-gas unstable light naphtha is sent to the light ends recovery section for recovery of LPG and light naphtha product.
De-Ethaniser The de-ethaniser remove light ends (C2), H2S, and water from the light naphtha and LPG. Feed enters the top of the column. The feed to the de-ethaniser comes from the combined liquid stream leaving the de-ethaniser reflux drum and is pumped to the top of the de-ethaniser.
Hydrogen Generation Unit The Unit is designed to process Straight Run Naphtha or Natural Gas to hydrogen that will cater to the needs of the new DHDT-MSQ and other units. The process involved for converting the Naphtha to hydrogen is steam reforming. Process licensor for HGU is HTAS, Denmark. The plant is divided into 3 sections: •
Desulphurization
•
Reforming
•
CO-Conversion
Sulphur Recovery Unit The unit consists of three identical units A, B and C. One of them is kept standby. The process design is in accordance with common practice to recover elemental sulphur known as the Clause process, which is further improved by Super Clause process. Each unit consists of a thermal stage, in which H2S is partially burnt with air, followed by two catalytic stages. A catalytic incinerator for incineration of all gases has been incorporated in order to prevent pollution of the atmosphere. The primary function of the waste heat boiler is to remove the major portion of heat involved in the combustion chamber. The secondary function of waste heat boiler is to condense the sulphur, which Page | 64
is drained to a sulphur pit. At this stage 60% of the sulphur present in the sour gas feed is removed. The third function of the waste heat boiler is to utilise the heat liberated there to produce LP steam (4kg/cm2). The process gas leaving the waste heat boiler still contains a considerable part of H 2S and SO2. Therefore, the essential function of the following equipment is to shift the equilibrium by adopting a low reactor temperature thus removing the sulphur as soon as it is formed. Conversion to sulphur is reached by a catalytic process in two subsequent reactors containing a special synthetic
Figure 29: OHCU Layout
alumina catalyst. Before entering the first reactor, the process gas flow is heated to an optimum temperature by means of a line burner, with mixing chamber, in order to achieve a high conversion. In the line burner mixing chamber the process gas is mixed with the hot flue gas obtained by burning fuel gas with air. In the first reactor, the reaction between the H 2S and SO2 recommences until equilibrium is reached. The effluent gas from the first reactor passes to the first sulphur condenser where at this stage approximately 29% of the sulphur present in the sour gas feed is condensed and drained to the sulphur pit. The total sulphur recovery after the first reactor stage is 89% of the sulphur present in the sour gas feed. In order to achieve a figure of 94% sulphur recovery the sour gas is subjected to one more stage. Page | 65
Feed The hydrogen generation unit can be fed either by naphtha or natural gas. The naphtha feed is pressurized to about 35 Kg/cm2 by one of t he naphtha feed pumps and sent to the desulphurization section. The pressurized feed is mixed with recycle hydrogen from the hydrogen header. The liquid naphtha is evaporated to one of the naphtha feed vaporisers. The hydrocarbon feed is heated to 380° to 400°C by heat exchange with superheated steam in the naphtha feed preheater.
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Chapter 8
Garage
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Diesel Engine A diesel engine (also known as a compression-ignition engine) is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel that has been injected into the combustion chamber. This is in contrast to spark-ignition engines such as a petrol engine (gasoline engine) or gas engine (using a gaseous fuel as opposed to gasoline), which uses a spark plug to ignite an air-fuel mixture. The engine was developed by German inventor Rudolf Diesel in 1893. The diesel engine has the highest thermal efficiency of any regular internal or external combustion engine due to its very high compression ratio. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can have a thermal efficiency that exceeds 50%. Diesel engines are manufactured in two stroke and four-stroke versions. They were srcinally used as a more efficient replacement for stationary steam engines. Since the 1910s they have been used in submarines and ships. Use in locomotives, trucks, heavy equipment and electric generating plants followed later.
How diesel engines work: The diesel internal combustion engine differs from the gasoline powered Otto cycle by using highly compressed hot air to ignite the fuel rather than using a spark plug (compression ignition rather than spark ignition). In the true diesel engine, only air is initially introduced into the combustion chamber. The air is then compressed with a compression ratio typically between 15:1 and 22:1 resulting in 40-bar (4.0 MPa; 580 psi) pressure compared to 8 to 14 bars (0.80 to 1.4 MPa) (about 200 psi) in the petrol engine. This high compression heats the air to 550 °C (1,022 °F). At about the top of the compression stroke, fuel is injected directly into the compressed air in the combustion chamber. This may be into a (typically toroidal) void in the top of the piston or a pre-chamber depending upon the design of the engine. The fuel injector ensures that the fuel is broken down into small droplets, and that the fuel is distributed evenly. The heat of the compressed air vaporizes fuel from the surface of the droplets. The vapour is then ignited by the heat from the compressed air in the combustion chamber, the droplets continue to vaporise from their surfaces and burn, getting smaller, until all the fuel in the droplets has been burnt. The start of vaporisation causes a delay period during ignition and the characteristic diesel knocking sound as the vapour reaches ignition temperature and causes an abrupt increase in pressure above the piston. The rapid expansion of combustion gases then drives the piston downward, supplying power to the crankshaft. As well as the high level of compression allowing combustion to take place without a separate ignition system, a high compression ratio greatly increases the engine's efficiency. Increasing the compression ratio in a spark ignition engine where fuel and air are mixed before entry to the cylinder is limited by the need Page | 68
to prevent damaging pre-ignition. Since only air is compressed in a diesel engine, and fuel is not introduced into the cylinder until shortly before top dead centre (TDC), premature detonation is not an issue and compression ratios are much higher.
Major advantages 1. Diesel engines have several advantages over other internal combustion engines:
2. They burn less fuel than a petrol engine performing the same work, due to the engine's higher temperature of combustion and greater expansion ratio. Gasoline engines are typically 30% efficient while diesel engines can convert over 45% of the fuel energy into mechanical energy.
3. They have no high voltage electrical ignition system, resulting in high reliability and easy adaptation to damp environments. The absence of coils, spark plug wires, etc., also eliminates a source of radio frequency emissions which can interfere with navigation and communication equipment, which is especially important in marine and aircraft applications.
4. The life of a diesel engine is generally about twice as long as that of a petrol engine due to the increased strength of parts used. Diesel fuel has better lubrication properties than petrol as well.
5. Diesel fuel is distilled directly from petroleum. Distillation yields some gasoline, but the yield would be inadequate without catalytic reforming, which is a costlier process.
6. Diesel fuel is considered safer than petrol in many applications. Although diesel fuel will burn in open air using a wick, it will not explode and does not release a large amount of flammable vapor. The low vapor pressure of diesel is especially advantageous in marine applications, where the accumulation of explosive fuel-air mixtures is a particular hazard. For the same reason, diesel engines are immune to vapor lock.
7. For any given partial load, the fuel efficiency (mass burned per energy produced) of a diesel engine remains nearly constant, as opposed to petrol and turbine engines which use proportionally more fuel with partial power outputs.
8. They generate less waste heat in cooling and exhaust.
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9. Diesel engines can accept turbocharging pressure without any natural limit, constrained only by the strength of engine components. This is unlike petrol engines, which inevitably suffer detonation at higher pressure.
10. The carbon monoxide content of the exhaust is minimal; therefore, diesel engines are used in underground mines.
11. Biodiesel is an easily synthesized, nonpetroleum-based fuel (through transesterification) which can run directly in many diesel engines, while gasoline engines either need adaptation to run synthetic fuels or else use them as an additive to gasoline (e.g., ethanol added to gasohol).
Supercharging and Turbocharging Most diesel engines are now turbocharged and some are both turbo charged and supercharged. Because diesel engines do not have fuel in the cylinder before combustion is initiated, more than one bar (100 kPa) of air can be loaded in the cylinder without pre-ignition. A turbocharged engine can produce significantly more power than a naturally aspirated engine of the same configuration, as having more air in the cylinders allows more fuel to be burned and thus more power to be produced. A supercharger is powered mechanically by the engine's crankshaft, while a turbocharger is powered by the engine exhaust, not requiring any mechanical power. Turbocharging can improve the fuel economy of diesel engines by recovering waste heat from the exhaust, increasing the excess air factor, and increasing the ratio of engine output to friction losses.
Turbochargers A turbocharger is a forced induction device used to allow more power to be produced by an engine of a given size. A turbocharged engine can be more powerful and efficient than a naturally aspirated engine because the turbine forces more air, and proportionately more fuel, into the combustion chamber than atmospheric pressure alone. Turbochargers were srcinally known as turbosuperchargers when all forced induction devices were classified as superchargers; nowadays the term "supercharger" is usually applied to only mechanically-driven forced induction devices. The key difference between a turbocharger and a conventional supercharger is that the latter is mechanically driven from the engine, often from a belt connected to the crankshaft, whereas a turbocharger is driven by the engine's exhaust gas turbine. Compared to a mechanically driven supercharger, turbochargers tend to be more efficient but less responsive. Twin charger refers to an engine which has both a supercharger and a turbocharger. Turbos are commonly used on truck, car, train, and Page | 70
construction equipment engines. Turbos are popularly used with Otto cycle and Diesel cycle internal combustion engines.
Ope rati ng Pr inc ipl e
In most piston engines, intake gases are "pulled" into the engine by the downward stroke of the piston (which creates a low-pressure area), similar to drawing liquid using a syringe. The amount of air which is actually inhaled, compared with the theoretical amount if the engine could maintain atmospheric pressure, is called volumetric efficiency. The objective of a turbocharger is to improve an engine's volumetric efficiency by increasing density of the intake gas (usually air). The turbocharger's compressor draws in ambient air and compresses it before it enters into the intake manifold at increased pressure. This results in a greater mass of air entering the cylinders on each intake stroke. The power needed to spin the centrifugal compressor is derived from the kinetic energy of the engine's exhaust gases. A turbocharger may also be used to increase fuel efficiency without increasing power. This is achieved by recovering waste energy in the exhaust and feeding it back into the engine intake. By using this otherwise wasted energy to increase the mass of air, it becomes easier to ensure that all fuel is burned before being vented at the start of the exhaust stage. The increased temperature from the higher pressure gives a higher Carnot efficiency. The control of turbochargers is very complex and has changed dramatically over the 100-plus years of its use. Modern turbochargers can use waste gates, blow-off valves and variable geometry. The reduced density of intake air is often compounded by the loss of atmospheric density seen with elevated altitudes. Thus, a natural use of the turbocharger is with aircraft engines. As an aircraft climbs to higher altitudes, the pressure of the surrounding air quickly falls off. At 5,486 metres (17,999 ft.), the air is at half the pressure of sea level, which means that the engine will produce less than half-power at this altitude, with a turbocharger this can be alleviated.
P res s ure Inc reas e/Boos t
In automotive applications, "boost" refers to the amount by which intake manifold pressure exceeds atmospheric pressure. This is representative of the extra air pressure that is achieved over what would be achieved without the forced induction. The level of boost may be shown on a pressure gauge, usually in bar, psi or possibly kPa. In aircraft engines, turbocharging is commonly used to maintain manifold pressure as altitude increases (i.e. to compensate for lower-density air at higher altitudes). Since atmospheric pressure reduces as the aircraft climbs, power drops as a function of altitude in normally aspirated engines. Systems that use a turbocharger to maintain an engine's sealevel power output are called turbo-normalized systems. Generally, a turbo-normalized system will attempt to maintain a manifold pressure of 29.5 inches of mercury (100 kPa). In all turbocharger Page | 71
applications, boost pressure is limited to keep the entire engine system, including the turbo, inside its thermal and mechanical design operating range. Over boosting an engine frequently causes damage to the engine in a variety of ways including pre-ignition, overheating, and over-stressing the engine's internal hardware. For example, to avoid engine knocking (aka detonation) and the related physical damage to the engine, the intake manifold pressure must not get too high, thus the pressure at the intake manifold of the engine must be controlled by some means. Opening the waste gate allows the excess energy destined for the turbine to bypass it and pass directly to the exhaust pipe, thus reducing boost pressure. The waste gate can be either controlled manually (frequently seen in aircraft) or by an actuator (in automotive applications, it is often controlled by the Engine Control Unit). Inter c ooling
When the pressure of the engine's intake air is increased, its temperature will also increase. In addition, heat soak from the hot exhaust gases spinning the turbine may also heat the intake air. The warmer the intake air the less dense, and the less oxygen available for the combustion event, which reduces volumetric efficiency. Not only does excessive intake-air temperature reduce efficiency, it also leads to engine knock, or detonation, which is destructive to engines. Turbocharger units often make use of an intercooler (also known as a charge air cooler), to cool down the intake air. Intercoolers are often tested for leaks during routine servicing, particularly in trucks where a leaking intercooler can result in a 20% reduction in fuel economy. (Note that "intercooler" is the proper term for the air cooler between successive stages of boost, whereas "charge air cooler" is the proper term for the air cooler between the boost stage(s) and the appliance that will consume the boosted air.)
Transmission A machine consists of a power source and a power transmission system, which provides controlled application of the power. Transmission is an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a live axle. Often transmission refers simply to the gearbox that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device.
The most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels. Such engines need to operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel. The transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are also used on pedal bicycles, fixed machines, and anywhere rotational speed and torque must Page | 72
be adapted. Often, a transmission has multiple gear ratios (or simply “gears”), with the ability to switch between them as speed varies. This switching may be done manually (by the operator), or automatically. Directional (forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply change the speed and torque (and sometimes direction) of motor output. In motor vehicles, the transmission generally is connected to the engine crankshaft via a flywheel and/or clutch and/or fluid coupling. The output of the transmission is transmitted via driveshaft to one or more differentials, which in turn, drive the wheels. While a differential may also provide gear reduction, its primary purpose is to permit the wheels at either end of an axle to rotate at different speeds (essential to avoid wheel slippage on turns) as it changes the direction of rotation. Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative mechanisms include torque converters and power transformation (for example, dieselelectric transmission and hydraulic drive system). Hybrid configurations also exist.
Manual type Manual transmissions come in two basic types:
•
A simple but rugged sliding mesh or unsynchronized/nonsynchronous system, where straight-cut spur gear sets spin freely, and must be synchronized by the operator matching engine revs to road speed, to avoid noisy and damaging clashing of the gears.
•
The now common constant mesh gearboxes, which can include no synchronised, or synchronized/synchromesh systems, where typically diagonal cut helical (or sometimes either straight-cut, or double helical) gear sets are constantly "meshed" together, and a dog clutch is used for changing gears. On synchromesh boxes, friction cones or "synchro-rings" are used in addition to the dog clutch to closely match the rotational speeds of the two sides of the (declutched) transmission before making a full mechanical engagement. The former type was standard in many vintage cars (alongside e.g. epicyclic and multi-clutch systems) before the development of constant mesh manuals and hydraulic-epicyclic automatics, older heavy-duty trucks, and can still be found in use in some agricultural equipment. The latter is the modern standard for on- and off-road transport manual and semi-automatic transmission, although it may be found in many forms; e.g., non-synchronised straight-cut in racetrack or super-heavy-duty applications, non-synchro helical in the majority of heavy trucks and motorcycles and in certain classic cars (e.g. the Fiat 500), and partly or fully synchronised helical in almost all modern manual-shift passenger cars and light trucks.
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Automatic type Most modern cars have an automatic transmission that selects an appropriate gear ratio without any operator intervention. They primarily use hydraulics to select gears, depending on pressure exerted by fluid within the transmission assembly. Rather than using a clutch to engage the transmission, a fluid flywheel, or torque converter is placed in between the engine and transmission. It is possible for the driver to control the number of gears in use or select reverse, though precise control of which gear is in use may or may not be possible. Automatic transmissions are easy to use. However, in the past, automatic transmissions of this type have had a number of problems; they were complex and expensive, sometimes had reliability problems (which sometimes caused more expenses in repair), have often been less fuel-efficient than their manual counterparts (due to "slippage" in the torque converter), and their shift time was slower than a manual making them uncompetitive for racing. With the advancement of modern automatic transmissions this has changed. Attempts to improve fuel efficiency of automatic transmissions include the use of torque converters that lock up beyond a certain speed or in higher gear ratios, eliminating power loss, and overdrive gears that automatically actuate above certain speeds. In older transmissions, both technologies could be intrusive, when conditions are such that they repeatedly cut in and out as speed and such load factors as grade or wind vary slightly. Current computerized transmissions possess complex programming that both maximizes fuel efficiency and eliminates intrusiveness. This is due mainly to electronic rather than mechanical advances, though improvements in CVT technology and the use of automatic clutches have also helped.
Cranes A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy things and transporting them to other places. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a man. Cranes are commonly employed in the transport industry for the loading and unloading of freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment. The first construction cranes were invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction – some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron
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Figure 30: A mobile crane
and steel took over with the coming of the Industrial Revolution. For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first 'mechanical' power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20 th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilised where the provision of power would be uneconomic. Cranes exist in an enormous variety of forms –each tailored to a specific use. Sometimes sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings. For a while, mini - cranes are also used for constructing high buildings, in order to facilitate constructions by reaching tight spaces. Finally, we can find larger floating cranes, generally used to build oil rigs and salvage sunken ships.
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Fork-lifts A fork-lift truck (also called a lift truck, a fork truck, or a fork-lift) is a powered industrial truck used to lift and transport materials. The modern fork-lift was developed in the 1960s by various companies including the transmission manufacturing company Clark and the hoist company Yale & Towne Manufacturing. The forklift has since become an indispensable piece of equipment in manufacturing and warehousing operations.
Figure 31: Forklift
Co unt erba lanc ed for k-l ift c omponents
A typical counterbalanced forklift contains the following components:
•
Truc k Fra me is the base of the machine to which the mast, axles, wheels, counterweight, overhead guard and power source are attached. The frame may have fuel and hydraulic fluid
tanks constructed as part of the frame assembly.
•
Co unt erweig ht is a mass attached to the rear of the forklift truck frame. The purpose of the
counterweight is to counterbalance the load being lifted. In an electric forklift the large leadacid battery itself may serve as part of the counterweight.
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•
Cab is the area that contains a seat for the operator along with the control pedals, steering
wheel, levers, switches and a dashboard containing operator readouts. The cab area may be open air or enclosed, but it is covered by the cage-like overhead guard assembly. The 'Cab' can also be equipped with a Cab Heater for cold climate countries. •
Ov erhe ad Gua rd is a metal roof supported by posts at each corner of the cab that helps
protect the operator from any falling objects. On some forklifts, the overhead guard is an integrated part of the frame assembly.
•
P owe r S ourc e may consist of an internal combustion engine that can be powered by LP gas, CNG gas, gasoline or diesel fuel. Electric forklifts are powered by either a battery or fuel cells
that provides power to the electric motors. The electric motors used on a forklift may be either DC or AC types.
•
Tilt C ylind er s are hydraulic cylinders that are mounted to the truck frame and the mast. The
tilt cylinders pivot the mast to assist in engaging a load.
•
Mast is the vertical assembly that does the work of raising and lowering the load. It is made
up of interlocking rails that also provide lateral stability. The interlocking rails may either have rollers or bushings as guides. The mast is driven hydraulically, and operated by one or more hydraulic cylinders directly or using chains from the cylinder/s. It may be mounted to the front axle or the frame of the forklift.
•
Carr iage is the component to which the forks or other attachments mount. It is mounted into
and moves up and down the mast rails by means of chains or by being directly attached to the hydraulic cylinder. Like the mast, the carriage may have either rollers or bushings to guide it in the interlocking mast rails.
•
Load Bac k Res t is a rack-like extension that is either bolted or welded to the carriage in
order to prevent the load from shifting backward when the carriage is lifted to full height.
•
A ttac hme nts may consist of forks or tines that are the L-shaped members that engage the
load. A variety of other types of material handling attachments are available. Some attachments include side shifters, slip-sheet attachments, carton clamps, multipurpose clamps, rotators, fork positioners, carpet poles, pole handlers, container handlers and roll clamps.
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•
Tire s either solid for indoor use, or pneumatic for outside use.
A ttac hme nts
Below is a list of common forklift attachments:
Dime ns ioning Dev ic es : Fork truck mounted dimensioning systems provide dimensions for the
cargo to facilitate truck trailer space utilization and to support warehouse automation systems. The systems normally communicate the dimensions via 802.11 radios. NTEP certified dimensioning devices are available to support commercial activities that bill based on volume.
S ide s hift er is a hydraulic attachment that allows the operator to move the tines (forks) and backrest
laterally. This allows easier placement of a load without having to reposition the truck.
Ro tator: To aid the handling of skids that may have become excessively tilted and other specialty
material handling needs some forklifts are fitted with an attachment that allows the tines to be rotated. This type of attachment may also be used for dumping containers for quick unloading.
Fork P os itione r is a hydraulic attachment that moves the tines (forks) together or apart. This
removes the need for the operator to manually adjust the tines for different sized loads.
Ro ll an d Ba rr el Cla mp Att ac hme nt: A mechanical or hydraulic attachment used to squeeze the
item to be moved. It is used for handling barrels, kegs, or paper rolls. This type of attachment may also have a rotate function. The rotate function would help an operator to insert a vertically stored paper into the horizontal intake of a printing press for example.
Carton and M ultipurpose
Cla mp A ttac hme nts are hydraulic attachments that allow the operator
to open and close around a load, squeezing it to pick it up. Products like cartons, boxes and bales can be moved with this type attachment. With these attachments in use, the forklift truck is sometimes referred to as a clamp truck.
P ole Att achm e nts : In some locations, such as carpet warehouses, a long metal pole is used
instead of forks to lift carpet rolls. Similar devices, though much larger, are used to pick up metal coils.
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S lip S he et Att ac hme nt (Pus h - P ull) is a hydraulic attachment that reaches forward, clamps onto
a slip sheet and draws the slip sheet onto wide and thin metal forks for transport. The attachment will push the slip sheet and load off the forks for placement.
Drum Ha ndle r A ttac hme nt is a mechanical attachment that slides onto the tines (forks). It usually
has a spring-loaded jaw that grips the top lip edge of a drum for transport. Another type grabs around the drum in a manner similar to the roll or barrel attachments.
Te les co pic Fork s are hydraulic attachments that allow the operator to operate in warehouse design
for "double deep stacking", which means that two pallet shelves are placed behind each other without any aisle between them.
Scales:
Fork truck mounted scales enable operators to efficiently weigh the pallets they handle
without interrupting their workflow by travelling to a platform scale. Scales are available that provide legal for trade weights for operations that involve billing by weight. They are easily retrofitted to the truck by hanging on the carriage in the same manner as forks hang on the truck. Any attachment on a forklift will reduce its nominal load rating, which is computed with a stock fork carriage and forks. The actual load rating may be significantly lower.
Mobile Oil Spill Recovery Unit (MOSRU) Various regulations are laid down by relevant government agencies concerning cleaning of oil spills, which need to be adhered, for safeguarding the environment. Until recent years there was no systematic method available for collection of leaked
petroleum
products,
causing
substantial environmental damage. MOSRU consists of a collection tank with 360° rotatable suction boom and a superior dual cooled (air + water cooled) vacuum pump or compressor system. The power to the system is given from the truck engine through the PTO, creating the required vacuum in the tank Figure 32: Indian Oil’s MOSRU Unit
for suction of the leaked product.
MOSRU comes equipped with a lighting system and an independent power generator, for carrying out operations during night and in remote areas. It also features a simplified control panel for easy operation, a corrosion resistant collection tank; convenient storage compartment for tools and Page | 79
accessories; and a large assortment of custom built accessories for added efficiency and long-term dependability. MOSRUs are custom-made in capacities depending on gross vehicle weight (GVW) of truck chassis (common tank capacities: 1500 litres on 5 tonne GVW chassis; 3000 Iitres on 10 tonne GVW chassis; 6000 litres on 16 tonne GVW chassis; 12000 Iitres on 25 tonne GVW chassis).
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a jr a h c a t t a h B p e d a r u o S
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