HUBCO Narowal Internship Report
Omar Farooq 2011906
9/1/15
Plant layout of HUBCO power plant and Specification of plant machinery
HUBCO Narowal Power Plant is a 225 MW power generation facility, located 16 km from Narowal city, Punjab Pakistan. The site was built by MAN Germany and handed over to HUBCO in 2011. Plant operations are overseen by TNBRP, a Malaysian firm. The facility cost 315.6 Million (EUR = 36.14 Billion PKR @114.5 rate). Net output of the power plant is 213.603 MW, which equates to 169.2 Million rupees per installed MW capacity. For comparison, the Tarbela Dam’s cost today is 10.37 Billion USD (= 1.06 Trillion PKR @101.7 rate). Net output of tarbela dam is 3478 MW which gives 303.3 Million rupees per installed MW capacity.
Plant layout of HUBCO Narowal power plant HNPP is a combined cycle diesel engine power plant. It has 11 diesel engines running on heavy fuel oil (HFO). Exhaust gases from each diesel engine is fed to a heat recovery steam generator or HRSG (a boiler), which produces steam to power a steam turbine. This combined cycle power generation system is illustrated in a diagram on the next page.
Maximum Power output Capacity: 18.9*11 + 16.34 = 224.24 MW The combined cycle results in an increased overall efficiency, and was a condition for the loan obtained from the World Bank.
Gate #. 3 Tank Yard
TNBRP office
Heating and decanting station
Fuel Water treatment treatment room room
Firefighting room
Workshop building Exhaust gas stacks
Engine radiators
Compressor room
Exhaust gas stacks
Steam turbine area
HRSGs (Boilers)
Engine auxiliaries
Engine room 2
HRSGs (Boilers)
Grid station
Control room building
Engine auxiliaries
Engine room 1
Condenser room
HUBCO office Towards Ataltec colony
Towards HUBCO colony
Wastewater treatment plant
Towards MAN colony
Warehouse
The Diesel engines Each of the engines present at HUBCO is a MAN turbocharged medium speed diesel engine. The engine model is 18V48/60
18V 48/60 Number of Engine type Bore Diameter* cylinders
Stroke length* *in cm
The engine running speed is 500 rpm (hence a medium speed engine), the mean effective pressure is 23.21 bar, and the effective power at crankshaft is 18.9 MW. The engine drives an alternator which produces electrical energy. As alternators have an efficiency >98%, this can be considered to be the same as the electrical power output per engine. Weight of the Engine is 255 Ton, while that of the crankshaft alone is 20 Tons! This helps illustrate is massive size!
The Steam Turbine The Steam Turbine is a 2 stage Dresser-Rand (Peter Brotherhood) turbine rated at 16.34 MW. The turbine along with its auxiliaries is shown in the figure on the next page. The functions and operating procedures are discussed below. The turbine is started on auxiliary oil pump. DC oil pump is a standby pump which kicks into action if the auxiliary oil pump fails. Auxiliary oil pump provides lubrication to the bearings when the turbine is in barring. The lube oil pump is used when the turbine’s rpm is increased from barring to the regular operating speed. After the turbine has been on lube on full speed for some time, it is shifted to the main oil pump instead. When the turbine is started, it does not go from 0 to 6000rpm in a go. Instead, it is first taken from stop to barring and maintained for 5 hrs with a 230 rpm, and then taken to full speed. Sudden change in operating temperature of the turbine is avoided in order to reduce effect of any thermal shock, which may not only crack the blades, but also decrease the life of the overall machine.
How diesel engine combined cycle is better than gas turbine combined cycle Power Plants Combining two or more thermodynamic cycles results in improved overall efficiency, reducing fuel costs. In stationary power plants, a widely used combination is a gas turbine (operating by the Brayton cycle) burning natural gas or synthesis gas from coal, whose hot exhaust powers a steam power plant (operating by the Rankine cycle). Combined Cycle Gas Turbine (CCGT) plant can achieve a best-of-class real (HHV) thermal efficiency of around 54% in base-load operation, in contrast to a single cycle steam power plant which is limited to efficiencies of around 35-42%.
The Comparison Comparison Criteria selection of power plant type is based on thermal efficiency, cost-effectiveness, and environmental impact. The performance parameters, i.e., thermal efficiency and heat rate are the most important factors in evaluation and comparison of various types of power plants. High efficiency is the primary prerequisite for making an economical choice of power plant. Thermodynamic superiority of combined-cycle power plants is their outstanding feature.
In combined cycle power plants, the efficiencies of diesel engines, steam power plants and single-cycle gas turbine power plants are surpassed. The best gas-fired steam power plants can attain efficiencies of about 45%. The simple-cycle advanced gas turbine efficiency at a turbine inlet temperature of over 1100 degree Celsius is around 37—38.5%, whereas advanced combined-cycle power plants attain efficiencies of or even higher (up to 58-60%).
Let us consider the following type of power plants: 1. steam turbine 2. gas turbine 3. diesel engines The efficiency of advanced diesel engines is comparable to that of gas turbines of equal power capacity, and therefore diesel engine power plants may appear to be the optimum option for smaller to medium power outputs, e.g., up to 30 MW, and in the most favorable Cases, even up to 50 MW.
At higher capacities, diesel engine power plants have higher capital and maintenance costs than gas turbine power plants. However, diesel engines have greater environmental impact, especially with the emissions of NOx and unburned hydrocarbons. Specific capital costs per kW of power output of combined-cycle power plants increase as the plant power rating decreases. Therefore combined-cycle power plants of smaller power outputs are suited for industrial or district heating cogeneration plants. However, the minimum economical size of the combined-cycle cogeneration plants based on the utilization of gas turbines is 10 MW. Power rating of diesel engines is even greater, in order to have sufficient amount of exhaust gases to be utilized by a HRSG unit. The second important criterion for comparing types of power plants is the economic factor. Steam power plants are significantly more expensive than combined-cycle power plants. A coal-fired power plant, for example, costs 2-3 times as much as a combined-cycle power plant with the same power output.
Advanced combined-cycle power plants are therefore simpler and less expensive than steam power units. Their construction period is shorter than that of steam power plants. A possibility of progressive staged construction of combined-cycle power plants is yet another advantage. At the first stage, the gas turbine plant is installed and commissioned. During the second stage, the steam plant train is installed. Construction costs of the steam plant will be financed from the revenues of electric power produced by the gas turbine plant.
Comparing both the performance and economic criteria shows that combined-cycle power plants have an evident advantage over simple-cycle plants such as steam or gas turbine power plants. Therefore combined-cycle power plants represent the optimum energy system type that is suitable for the construction of new power plants and for upgrading and of existing steam power plants.
Operating Costs Because of the high reliability of advanced gas turbines, simple-cycle gas turbine plants have the lowest operating and maintenance (O and M) costs, although they require more spare parts than steam turbines. A steam power plant requires more staff, and its maintenance costs are higher. O and M costs of combined-cycle power plants depend on the complexity of the steam portion and are between those of simple-cycle gas turbine plants and steam power plants.
Availability and Reliability Major factors determining power plant availability are • Design of the major components • Mode of operation (base, medium, or peak load) • Type Of fuel All the power plants under consideration have similar availabilities when used under the same operating conditions. Typical figures for the availability of base-load power plants are as follows:
gas-fired gas turbine power plants 88—95% Oil- or gas-fired steam turbine power plants 85-90% coal-fired steam turbine power plants 80—85% gas-fired combined-cycle power plant 85—90%
The availability of peak and medium load machines is lower because of frequent start-ups and shutdowns that reduce life of the machine and thus increase the scheduled maintenance and forced outage rates. Frequent shut downs has a more detrimental effect on gas turbine power generation units than diesel engines
Fuel costs
Fuel expenditure of gas turbine power plants are generally greater. Greater fuel purification is required due to increased instances of corrosion occurrence in gas turbine engines. Diesel engines on the other hand are insensitive to the presence of impurities such as Metals or salts in the fuel. The fuel required is more expensive itself. Unlike steam power plants that can be fired with any fuel or diesel engines that may run on HFO, gas turbine power plants employ only natural gas or light distillate (LFO) as fuel. Both of these fuels are more expensive than coal for steam power plants, or HFO in the case of diesel engines. Fuel price is an essential constituent of electricity costs. Therefore, as a rule, coalfired reheat steam power plants produce electricity cheaper but at a higher environmental impact than power plants based on gas-fired gas turbines.
Among all Oil- Or gas-fired power-stations, the combined-cycle power plant is the most economical technology for electricity generation. For short utilization periods of peak-load plants with annual service of up to 2000 h/yr. for gas-fired large-capacity power plants and up to 1500 h/yr. for oil-fired smaller units, the gas turbine is the most economically viable choice. Coal-fired steam power plants are
suitable for use as base-load plants if the price difference between the coal and the gas turbine fuel is sufficiently large (around PKR 300-600/GJ).
Combined-cycle power plants with supplementary firing represent a viable option for re-powering as well as for application in cases when the gas or oil supply is scarce and the more easily available fuel is coal for use in supplementary firing.
To summarize, benefits of using diesel engines over gas turbines are as follows:
Instantaneous switchover from gas to fuel oil Switch fuels while maintaining full load Insensitive to metals and salts in fuel oils No increased maintenance needs when running on fuel oil Fuel sharing operation
Fuel Selection The selection of the fuel and the corresponding type of power plant is determined not only by shortterm economic considerations also by long-term developments in the prices for the various possible fuels. In this regard, the following aspects can become important in selecting the type of power plant to build long-term availability of the fuel at a favorable price and also satisfy environmental concerns.
Line diagrams, assignment 4 Decanting process: assignment 5 Assignment 6: How maintenance process is executed (PM and CM) which includes work order, issuances of spares, closing of permit etc
Conclusion Overall, my internship experience at HUBCO Narowal was a truly enriching one. I got to see for myself the operation of a power plant, and since I wish to work in Pakistan’s energy sector after completing my engineering degree, this was a very meaningful and valuable experience.
