Vol: 4 SNG and LPG
Systems Over Overv view A Handbook from the SNG Academy ™
Tulsa, Oklahoma, Ok lahoma, USA
LPG and SNG Systems Overview Table of Contents C ontents History & Abstract � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 2 General Business Description � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 2 Te Company � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 2 Purpose o the handbook� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 4 SNG System Overview � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 4 U � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 6 SNG System Owner Responsibility � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 8 LPG Cylinder Filling � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 9 LPG Storage anks � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 11 LPG Pumps� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 16 LPG Vaporizer� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 17 SNG Blenders � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 19 Venturi SNG Systems � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 20 Proportional SNG Systems � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 23 Old Fashioned Piston ype Mixers � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 25 SNG to NG � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 27 Properties o LPG � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 28 Codes & Standards (USA)� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 30 LPG Saety Components � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 31 Combustion Characteristics o LPG � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 33 SNG System Operation, Maintenance and Malunctions � � � � � � � � � � � � � � � � � � � � � 34 Emergency Procedures� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 38
Disclaimer o Responsibility: Ely Energy Inc. does not warrant or assume any legal liability or responsibility or the accuracy, completeness, completeness, or useulness o any inormation, apparatus, product, or process described herein. Ely Energ y Inc. assumes no liability or the misuse, abuse, or incorrect application o dat a presented. This Handbook does not purport to cover all details or varia tions in equipment nor to provide for every possible conti ngency to be met in connection with installation, operation, maintenance or training. Should urther inormation be desired or should particular problems arise which are not covered sufciently or the readers purposes the matter should be reerred to Ely Energy Inc. in
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LPG and SNG Systems Overview
History & Abstract Synthetic Natural Natura l Gas (SNG), (SNG), plays a niche role, yet a critical role in meeting the t he energy needs o nations around the world� world� SNG is a term term that describes descr ibes a variety o “manuactured “manuactu red gases”� In our lnguge, SNG is blend of Liquefied Petroleum Gs (LPG) nd ir tht provides direct replcement r nturl gs.
Tis handbook ha ndbook provides basic inormation and describes concepts and equipment common to the SNG industry� Our presentation is intended to assist personnel who are involved with SNG systems and equipment�
History of Ely Energy, Inc. From 1898 to the 21st-Century…
In 1898, 1898, Energy Energy Systems, Inc� (ESI) began bega n as a mechanical contractor located located in southern Minnesota (USA)� By the 1950’ 1950’ss ESI had branched out into associated as sociated mechanical mechanica l engineering activities that grew to include design and manuacture o Synthetic Natural Gas (SNG) (SNG) systems� Teir applications applications included included peak shaving or natural natura l gas utilities and industry, industry, backup uel systems and a nd CityGas distributed d istributed gas systems� Around A round 1980, 1980, ESI was acquired by the RJ Ely Company o ulsa, Oklahoma (USA) and began operations as Ely Energy Systems, and later as Ely Energy Inc� — a subsidiary o the RJ Ely Company� In 1998, under a corporate c orporate consolidation, the corporation ormally ormal ly changed to Ely Energy, Inc� (EEI)�
General Business Description EEI specializes specializ es in specic niche market opportunities opportunities that typically t ypically involve involve LPG (liqui (l iquid d red petroleum gases) ga ses) or NH3 (ammonia)� (ammonia)� Te cornersto cornerstone ne o EEI’s EEI’s business is i s the so-called so-ca lled synthetic natural natura l gas (SNG) (SNG) group group that oers solutions solutions to assist in i n natural natura l gas ga s management� Most people have heard heard o natural natur al gas� ga s� Some have heard o liqueed petroleum gas (LPG)� (LP G)� Few outside the energy energ y sector, however, however, understand SNG� We create SNG by blending LPG with air to a specic ratio that results in a uel with combustion characteristics essentially identical identical to natural natu ral gas� ga s� Tis precise and controlled controlled mixing o LPG and air allows a llows it to be used as an alterna a lternative tive to natural gas or “backup “ backup”” use, ‘peak shaving’, shaving’, and CityGas CityGa s supply supply in regions where natural gas is not yet available� No orice changes, pressure changes or any other changes are required to the natural gas consuming equipment! SNG is a direct replacement or natural gas (NG)! Te technology o blending LPG and Air to simulate natural gas is not new — SNG extends back to the 1950’ 1950’s� s� What W hat is new is our ability to provide much higher degrees o control, control, gas quality consisten c onsistency cy and a nd saety to the t he process� Our SNG solutions solutions assist in natural natu ral gas ga s energy management mana gement or or private industry, the ederal government, the U�S� military militar y, municipalities, educational and correctional correctional institutions i nstitutions and the medical-health care sector� We oer solutions in various orms, typically involving the installation o an on-site SNG system or either ‘standby’ or ‘base load’ use� With ancestral roots that trace to 1898, EEI is easily one o the most respected SNG 2
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equipment and service providers in the world� Our commitment is to optimize our available resource base to make every project successul� We provide a variety o SNG energy services including: ■
SNG Backup Systems: Allow the industrial natural gas customer to change rom a FIRM FIR M to an INERRUPIBLE INERRUP IBLE Natural Natural Gas rate structure� structu re� Te savings will oten pay or or an installation inst allation within 6 mo� or less, up to 4 years�
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SNG Peak Shaving Systems of NG: SNG is used by both NG Companies and Industrial Clients to augment their NG demand during peak pea k demand periods�
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SNG Base-Load Systems: Provide SNG in regions where NG is currently not available� SNG provides a bridge uel or a long-term solution or or an energy energ y need�
The Company We can be contacted c ontacted at ax a x (91 (918) 254-54 254-5412 12 (USA) or at our e-mai e-mail:l: sales@elyenerg sa les@elyenergyy�com� Our telephon te lephonee switchboard sw itchboard is at (91 (918) 250250-6601 6601�� ouch ouch ‘0’ or the t he Operator to direct d irect your call� ca ll� Or visit us on the Internet at www.elyenergy.com at www.elyenergy.com�� Our physical physica l address is 1138 11385 5 East 60th Place South, ulsa, ulsa , Oklahoma Okla homa 741 74146 46 (U�S�A�) (U�S� A�)��
AQUA-GAS ® under manuacture at Ely Ene rgy.
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LPG and SNG Systems Overview
Purpose of the Handbook Te purpose o this handbook is to provide inormation on the properties o LPG and basic operation o an SNG system� Tis includes basic saety and operational inormation� Any training tra ining must be conducted by a technician trained in the t he properties properties o LPG and a nd the application o LPG equipment to “real lie” scenarios� Handbook Includes: • •
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An overview o LPG and a nd SNG SNG systems An introduction to the basic properties o LPG and how those properties impact the operation o an SNG system An introduction to applicable codes and standards used to design, manuacture, and maintain sae sa e operation operation o an SNG system Teory o operation o major subsystems o an SNG system Basic maintenance requirements How to recognize non-standard operating and emergency situations
Handbook Does Not Include: • • •
Details o combustion or “plant specic” burner applications Review o all code requirements requirements Knowledge or training necessary necessar y to make design changes to an LPG or SNG system
SNG System Overview Purpose o an SNG System:
o provide a substitute synthetic natura nat urall gas (SNG) to replace or augment augment natural natural gas� gas� SNG burns burns with similar characteristics char acteristics as natural gas� ga s� SNG requires no changes to pressure regulators regu lators or burner burner orices� SNG is introduced introduced at the same pressure as natural natu ral gas� ga s� SNG provides provides a similar similar “energy value” to natural natur al gas gas (wobbe (wobbe index) at the burner tip� • • • •
SNG systems utilize ve basic subsystems: Truck Trnsfer Unloding acility (U) to receive liquid LPG rom a transport •
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(~ 9,000 US gal gallons/load)� lons/load)� LPG Strge Tnks to store the liquid LPG� An LPG pump system to transer and elevate the pressure o the liquid LPG rom the tanks tank s to the vaporizer� vaporizer� An LPG vporizer to heat the liquid LPG and change it into the vapor (gaseous) phase� An LPG/Air blender to blend blend the necessary necessa ry air a ir with the t he LPG vapor to create SNG�
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A “tie-in” point to the existing natural gas piping is another subsystem� Almost always, this point is just downstream of the existing service regulator/meter at the natural gas Note:
entrance to the plant. Five Key Subsystems n SNG system TTU/cylinde TTU/c ylinderr filling LPG Strge LPG Pump System LPG Vprizer SNG Blender
Discussion Topics
1. 2. 3. 4. 5.
Typical small capacity SNG System Layout
Optional components may also be associated with an SNG system (examples include): U to inject methanol into the storage storage tanks ta nks Methnol injector system located at the U •
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to remove water which may be in the LPG� SNG metering system usually located at the outlet o the SNG blender to provide an accurate measurement o the SNG used� A ‘Gs Qulity Instrument’ to ensure the SNG has the proper energy content to replicate the energy valve o the natura naturall gas� Flre Stck allows testing the t he LPG air system at any time without running it into into the plant or to ensure the SNG mix is good prior to sending it into the plant� Nturl Gs pek shving cnfigurtins allow SNG to augment the ow rate o natural gas either by pressure or ratio control� Remte mnitring system to provide annunciation o key saety limits and the ability to adjust ow rates rom a remote location� www.elyenergy.cm
LPG and SNG Systems Overview
TTU TT U (Truck Transport Transport Unloading Facility) A normal U U o-loads a 9000 gallon ga llon (34m3) transport tra nsport in about 1 hr and 15 15 minutes� Tis rate o o-loading is based on using a 2 liquid line and 1 ¼ vapor line with valving sized or the pipe� Liquid Liquid is extracted e xtracted rom the transport tra nsport via the larger lar ger diameter line� Te smaller diameter line prevents prevents a vacuum orming in the truck by allowing a llowing the pressures to equalize between the truck and the storage tank� A common cause o accidental accidental spills o LPG is a pull-awa pul l-awayy at an LPG L PG transer area� a rea� Te term “pull-away” reers to an accident caused by a bulk truck moving away rom the transer point with the transer hoses still connected to the U� A pull-away could break a hose, or in a severe case, case , pull out the piping net network� work� In either case, ca se, a pull-away would create a large LPG spill and possibly result in a re� o avoid these problems the U design incorporates a robust steel bulkhead set in a massive concrete oundation� oundation� Te U U utilizes utilize s shear ttings that “break away” in a designed ashion in the event o an accidental truck pull-away� Te U is protected by large steel or concrete posts to prevent vehicles rom colliding with the t he critical piping� piping� Industry studies prove prove a point o ailure can be predicted and that a specic pull-away orce can be determined at which the piping will rupture in a “clean break�” Tese studies have resulted in designs aand nd connections using Schedule 80 pipe nipples and coupling couplings� s� An example o a U bulkhead is shown on the opposite page� "
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The key components o the TTU include: • • • • •
Steel bulkhead congured to meet code, including including risers and a nd concrete� concrete� “Acme” ttings to connect to hoses which normally come with the transport� tra nsport� Back Check Valve on the liquid line� Hand-operated back check valve on the vapor line� Emergency Saety Shutdown system (ESS Station)�
About the TTU
Te U is designed to cause a predictable shear ailure by utilizing orged steel pipe couplings welded vertically vertic ally into a reinorced steel channel ch annel member and mounted onto onto two legs� Te U is set into a hole approximately 4t by 4t lled with concrete� Tis design protects the structura str ucturall integrity o plant piping piping and equipment should should a pull-away pul l-away occur rom any angle or position� Force applied applied to the vertic vertical al pipe nipples nipples above the horizontal horizontal bulkhead bul kheadss channel results result s in deormation o the pipe nipple threads� Te threads continue to deorm as more orce is applied until the pipe nipple pulls out o the coupling� Automatic valves on the tank side o the U will then immediately shutdown the ow o LPG rom the piping system� A pull-away orce can be selected that would be greater than any orce expected in normal operations operations and smaller than tha n that which might cause c ause hose rupture or which could pull out 6
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Typical TTU (Truck Transport Unloading) Station with Emergency Pull Cable. Reer to the current or appropriate version o NFPA 58 or requirements.
the valves valves rom the vehicle tank� tank � esti esting ng indicates a 2-inch hose requires almost al most 8000 lb� to break (or pull o certain ttings); a 3-inch hose requires about 11,000 lb� to ailure� Tere are several additional desirable eatures o this vertical vertica l coupling breakaway system� ests show that nipples pulled out completely will result in sudden release o LPG� Tis will cause slugging o the system’s excess ow valves� Additionally, i the pullout nipple is mounted above the coupling, the released relea sed LPG will wil l go straight straig ht up� up� Tis is the most desirable direction or sae dissipatio di ssipation n o the LPG� Te most important attribute attribute o this system is that t hat the pulling orce can ca n come rom any direction without compromising the design�
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LPG and SNG Systems Overview
SNG System Owner Ow ner Responsibilities: LPG Transfer According to NFPA 58, during the LPG transer process, at least one qualied and trained person must remain in attendance rom the time connections are made rom the truck to the U, U, until until the valves are closed and the transer hoses are disconnected� Without direct control as provided by the person delivering LPG, it is difcult difc ult to insure all steps are properly and saely completed� Oten SNG system owners leave all transer responsibility with the LPG supplier� Since most accidents happen during LPG transer, a greater role should be taken by the SNG system owner� At a minimum, SNG system owners should: •
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Keep a log o tank volumes volumes and make their own calculations ca lculations to conrm that the t he tank(s) tank(s) can ca n accept the t he volume volume o LPG ordered� ordered� When the SNG system has ha s more than one tank, tan k, provide provide a plant person during the transer tra nser to insure the LPG goes into the correct tank(s ta nk(s)� )� I your LPG supplier supplier handles more products than LPG, make your own conrmation that the delivered product product is LPG� LPG � ake any additional steps necessary necessar y to improve improve the reliability and saety sa ety o LPG delivery� Conrm that t hat the tank( ta nk(s) s) are not over over lled�
The LPG vendor making delivery o LPG should: • • • • • • • • • • •
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Inspect the general area or hazards and access or their truck� Position Position the truck correctly correct ly and chock the wheels� Inspect the truck or damage� Check the contents contents o the truck t ruck to conrm conr m the product is LPG� Perorm Perorm a ‘sni’ ‘sni ’ test to conrm c onrm an odorant is present� Record the pressure and temperature temperature readings o the LPG tank� t ank� Determine the maximum amount o LPG which can be added to each tank� ta nk� Connect the transer hoses� ranser the LPG� Disconnect the transer hoses� Prepare the truck or departure�
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LPG Cylinder Filling Filling Cylinders
Tis brie training overview does not include sufcient detail to instruct the readers to become ully competent to perorm ull inspections o cylinders prior to lling� However, all al l operators are expected to ollow ollow the procedures and set aside all suspect su spect cylinders cylinders or urther inspection by your LPG supplier or cylinder supplier� Inspect the Cylinder Filling Area
LPG lling or dispensing stations should be kept kept clear o trash tra sh and debris� An accuacc umulation o leaves and other combustible materials pose a signicant re hazard and may interere with operation o the transer equipment� During transer tr anser operations, remove all sources o ignition within 25 eet o a point point o transer� tra nser� Shut Shut down internal combust combustion ion engines within withi n 15 15 eet o a point point o transer trans er when a transer tra nser operation operation is in progress�
UFM Filling machine Modern LPG cylinder lling machine using a small PLC and weight based lling.
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LPG and SNG Systems Overview
LPG Cylinder Filling Inspect the Containers and Valves
Check the retest date on each cylinde c ylinderr and be aware o the t he inspection periods periods and type t ype o retests required or various DO cylinders� Note that relie valves in orklit cylinders must be replaced 12 12 years ater a ter manuacturer and a nd every 10 years years there t hereater� ater� You must also conrm that all cylinders are tted with an OPD (overll prevention device)� Check containers containers to be lled or visual visua l evidence o damage to valving va lving or to the container walls rom any o the ollowing: Fire dmge. I there is eviden ev idence ce that the protective coating has been burned o any portion o the cylinder surace, or the t he cylinder body is warped or distorted, d istorted, it must be assumed that t hat the cylinder c ylinder has been overheated overheated and must be removed rom service� Check with your cylinder c ylinder supplier supplier�� Dents. Dents are deormations deormations caused by the t he cylinder coming in contact with a blunt blunt object in such a way that th at the thickness th ickness o the metal meta l is not materially impaired� Some dents which do not include a weld or are not sharp or dened may be tolerated� Check with your cylinder supplier� a re deormation deormation caused by contact Cuts, Guges nd Digs. Cuts, gouges, and digs are with a sharp shar p object in such a way as to cut into into or upset the metal o the cylinder, der, decreasing the wall thickness t hickness at that th at point point and raising the stresses stres ses in the material� Reer all al l gouged cylinders to your cylinder supplier� supplier� pitting invo i nvolves lves the loss o wall wa ll thickness t hickness by corrosiv c orrosivee Crrsin. Corrosion or pitting action� Reer these cylinders to your supplier� Leks. Permanently Permanently remove remove ALL cylinders with leaks, leak s, other than leaks lea ks at ttings which can be tightened t ightened,, rom service� Neck Flnge r Ft Ring Deects. Check both areas or damage along with damage to valves or gauges� c ylinder,, indicating LPG as a s the contents� Mrkings. Code requires labels on each cylinder •
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When filling by vlume, open then close the xed liquid level gauge to be sure vapor vents
rom the bleeder orice� I no vapor escapes, the orice may be blocked and must be reopened beore the gauge will w ill operate properly� properly� Do not attempt to ll a cylinder by volume i the t he xed level gauge is damaged or inoperable� Connect the ller hose and ollow your written instructions inst ructions to operate your lling equipment� Open the xed liquid level gauge and ll until a white mist appears� a nd set the scale sca le or the tare weight o When filling by weight set the container on the scale and the cylinder plus the weight o the LPG plus the weight o the hose and a nd ttings� When W hen nished lling, veriy weight to insure cylinder is not not overlled�
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LPG Storage Tanks Capacity o Storage Tanks
Te amount o LPG storage to have on site site is based on the maximum ma ximum time time desired between bet ween LPG lls� Since LPG liquid (propane) contains 91,500 Btu/Gallon, there are about 11 gallons required or every one million BU’s (1 MMBU) required by the acility� Note also that one MMBU = 1 decatherm as a s 10 therms x 100,000 BU/therm = 1,000,000 BU� E x aM PLE PL E : a ctry uses mimum mimum 800 Dectherms, r 800 MMBTU per per dy. dy. The equivlent equivlent LPG consumption would be 800 x 11 11 or 8,800 8,8 00 gllons/dy. When selecting the appropriate size of your storage tanks, consider: averge daily cnsumptin LPG. The lgistics LPG deliveries. LPG tnks cnnt be filled cmpletely; ssume 85% 85 % usble. Lrger stndrd size tnks cme in 18,000 US gllns [67m3], 30,000 [112m3] nd 60,000 [224m3] sizes. According to code, LPG storage tanks are required to have specifc fttings. These fttings include : Relie vlve(s) Ecess fw nd shut vlves n vpr pening Bck check nd shut vlves n liquid inlet penings Internl vlve Fied liquid level guge Vrible liquid level guge Pressure guge Temperture guge •
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Simplied depiction o a typical LPG storage vessel with appropriate trim components.
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LPG and SNG Systems Overview
LPG Storage Tanks Te available storage o LPG is about 85% 85% o o the total water gallon ga llon capacity o a tank� tank � Tis lling technique provides or approximately 15% vapor space to allow or liquid expansion and “boil o o ” o the LPG� anks ank s are typically t ypically,, but not always, rated or a maximum max imum operating pressure o 250 psig� I rated at 250 psig, the “burst” or “design” pressure is 4 times the operating pressure or 1000 psig� Te point is, they do not break apart or any reason except or re or similar catastrophic events� Pressure in an LPG L PG storage tank tan k is related to temperature� Tat temperature temperature is normally at or near the ambient temperature o the outside air� The crrespnding •
pressure is clled equilibrium pressure. •
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For propane at 0 oF, the pressure is 24 psig� At A t 110 110oF, the pressure pre ssure is 197 psig� Te tanks tank s pressure relie valves are a re generally designed to relieve at 250 psig� Te release valves are located on the top o o the storage tanks� tank s� anks are required to be painted silver or white — only � Tese colors reect sunlight and keep the tank t ank as a s cool as possible� possible� In most parts par ts o the world, it is rare that t hat the ambi a mbient ent temperature temperature ever gets high enough to cause the relie valves to discharge� disch arge� However, However, regions such as the t he Middle East and Southeast Asia are exceptions� exceptions� anks are normally installed insta lled to provide provide at least 3 eet rom the belly o the tank t ank to the ground� Tis allows a llows the tank ta nk to provide enough enough hydraulic head to the eed the t he LPG to the pumps� Pressure in the tank tan k is generated generated by the LPG boiling o in the same way that water boils boil s at 212oF� When water boils steam is created and i the t he steam is contained, as with a tea te a kettle, pressure builds� With our tea kettle, the pitch 212 oF due to the confning presincreases as the t he temperature temperature climbs (above the 212 sure) and this increase in pressure is heard as a s a higher pitch� In the sa same me way, way, propane propane creates higher and higher pressures as its temperature rises above its boiling point o -44°F�
Note: The boiling point of propne is –44 –4 4oF! Tus, i the outside air temperature was say,
-45°F (very (very cold), propane would simply ow onto the ground and remain rema in as a liquid — no vapor� We could carry propane with an open bucket� At 100oF, i liquid propane leaks out o the pipe, it will immediately boil and become vapor and dissipate dissipate into the atmosphere� atmosphere� A cooling eect occurs when LPG vaporizes and this is the reason why a storage tank ta nk cannot normally be used as a s a vaporizer� I you contincontinually remove vapor via a vapor line on the top o a storage tank, you are relieving pressure rom the tank� But the tank will wi ll stay at equilibrium, equilibrium, so this results in LPG boiling (vapor(vaporizing) to restore the tank back into equilibrium� Obviously, this boiling requires heat and this heat comes rom the available ambient temperature o the LPG� Te result is the tem12
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perature o the LPG will be reduced as heat, or energy is extracted� Tis result in a lower vapor pressure in the tank which wh ich also reduces the rate at which the LPG can ca n boil or vaporize vaporize�� Over time, the LPG temperature continues to drop so low that there is little vapor available to be ed to the vapor consuming process� proce ss� Te solution to this problem, o course, cours e, is to have an LPG vaporizer installed� It should be noted noted that any a ny signicant leak in an a n LPG system sy stem usually results resu lts in ice ormation at the point o the leak� Te ice is created because o the cooling eect o the LPG vapor as it hits the atmosphere which contains moisture� Another A nother way to nd leaks is to see i i there are any ies ies hovering hovering around the tank ta nk or piping� piping� For some reason ies love love the stu st u!! Liquid Level in a Storage Tank
Te level o the liquid LPG in a tank is usually measured by one o two available devices� A “Magnetel” gauge consists o a oat on a long arm installed insta lled internal to the storage tank� tank � Te oat rides up and down on the surace o the liquid LPG as the level changes� A pointer pointer on the ace o the gauge indicates i ndicates the percentage o liquid LPG in the tank� tank � Another type ty pe is a “rotary” gauge or so called c alled “Spit “Spit Gage”� Gage”� Tis is a long tube inside the liquid liquid you can manually rotate through the t he LPG liquid surace� A small hole on the ace o this gauge allows the LPG to “spit” out when the end o the arm inside the tank t ank hits the surace� surac e� At this t his point you simply simply look at the indicator dial to estimate the % ull o the tank� •
•
An 85% outage gauge should be mounted on every tank at the 85% ull level� Normally, Normally, during the lling lling process this t his needle type t ype valve is opened by the person lling the t he tank to ensure the tank tan k isn’t isn’t over lled� I liquid LPG gets to this level, level, there is a small release o liquid indicating indicating that the t he tank is ull� ull� Moving the pointer on the Rotary dial causes the end o the tube to rotate until it contacts liquid in the tank. At that point, discharge rom the bleed orice turns rom LPG vapor to liquid. The rotar y gauge dial provides the volume percentage o liquid in the tank.
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LPG and SNG Systems Overview
LPG Storage Tanks Determining Maximum Fill Volume or LPG Storage Tanks
NFPA NFPA 58 Section 4-4�2�2 lists list s the maximum ll allow a llowed ed in any LPG container� Te basis o the calculation is that LPG liquid expands dramatically on a rise in temperature� A vapor expansion space must always be allowed in the tank� Each tank ta nk is required to have a xed maximum max imum liquid liquid level gauge� Since the gauge is xed, xed, it may not not be suitable or determining the proper amount to ll a tank i the temperature o the LPG is low� Reer to the table (right) to determine the maximum max imum level permitted or LPG:
ProPane Storage tank MaxiMuM Fill level Tank TemperaTure
above ground
below ground
-10
80 %
82 %
0
81%
83 %
-10
82 %
84 %
20
83 %
85 %
30
84 %
86 %
40
86 %
87%
50
87%
89 %
60
88 %
90 %
70
90 %
91%
80
91%
93 %
90
93 %
95 %
Tere are tw cmmn miscnceptins regarding the maximum maxi mum ll volume volume o LPG tanks: I you never ll over 85% you will be sae� Te colder it it is, the t he more LPG you can saely put in the tank� ta nk� • •
85% gure gure is wrong because becau se it only applies when the liquid temperaBoth re wrong! Te 85% ture is i s above 35°F 35°F�� Te second myth is wrong because i you overll when w hen it is cold, and then the temperature rises — you will over pressurize pressurize the tank and the relie valves will relieve� Saety Considerations Consideration s or an LPG Storage Tank: Steel integrity: Properly paint the tank and rest it on elt pads in the concrete saddles�
Otherwise, rust ru st will “pit” “pit” the tank surace and eventually threaten the tank tan k integrity� integrity� Pitting also reduces potential potential resale resa le value o a tank� points� Tese points points Cnnectins: Te greatest risk points with a tank are its penetration points� are where LPG, either liquid or vapor, enter or exit the tank� ypically there are three bottom connections to an LPG tank� tan k� Tese include: a) liquid liquid LPG into the tank rom the U, U, liquid liquid LPG out o the tank to the vaporizer or process, and LPG a bidirectional ow o vapor into and out o the tank (In the case o vapor, one pipe accomplishes this�)
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Protect Penetrations into the Tank — Several techniques and components are used: •
•
•
•
Te connections must must be 6,000 6,00 0 psig steel ttings welded to the tank ta nk according to ASME and DO standards� (Both NP N P and anged connections are available�) Te vapor connection is protected protected using an excess ow valve and isolation valve� check vlve or a combination Te liquid inlet is protected using an inline bck check vlve internl/ecess fw vlve with remte shut . Te liquid outlet opening is protected by the combination internal/excess ow valve with remote shut-o� Immediately downstrea downstream m o these valves, manual isolation valves are usually installed� instal led� Tese valves may be either a ball valve va lve or globe valve rated o orr LPG service� Another means o protection or piping susceptible to damage due to tank settling, or expansion / contraction is use o a “swing” joint� A swing joint consists o two 90 degree bends in transition piping� Another option would be to use a stainless steel braided ex connector connector rated or LPG service� ser vice� Either method satises NFPA 58 and 59 code requirements or pipe protection� All LPG piping must be Schedule 80 i screwed (i�e� with NP connections) or Schedule 40 i welded�
On the let are two LPG rated stainless steel braided fex connectors, rom the tank valving to the tank systems headers. On the right, conventional swing joints at 90 ° are built into the system piping to accept expansion and contraction.
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LPG and SNG Systems Overview
LPG Pumps Te LPG pumping system is a critical link in an LPG or SNG system� Faulty motors, leaks in the pump seals or problems with the back pressure regulator can cause the entire system to go down� Tat is why nearly all instal inst allations lations utilize utilize a “duplex” pump design� design� wo wo pumps are provided in parallel with either pump available or immediate use� See the diagram below or basic pump components and operation� Te pump and its controls ensure LPG is delivered del ivered at the proper pressure and ow� Te pumping pumping system and a nd its associated piping piping and valves are a re part o an overall system s ystem specially designed or the application� It should not be changed in any way unless unle ss the designer desig ner is well experienced experienced in LPG pumping systems� Pumps installed at Venturi type SNG Blending systems increase the LPG pressure to provide provide the required motive pressure to the t he venturi� Tis allows a llows the venturi to properly mix the t he correct air to LPG ratio to create the SNG� Any pressure created above the desired pressure set point is relieved back to the LPG storage tank� o protect the pump and the downstream piping rom excessive pressure pressure in the event the primary primar y control valve ailed, a secondary relie valve or bypass is used� During warm w arm or hot weather, weather, exercise caution with an a n LPG pump� Te high ambient temperatures temperatures could allow al low the pump to develop develop very high pressures downstream� I the tank tan k pressure is sufcient, a standby system might mig ht be operated without a pump during very warm temperatures� Typical STABILIZER™ STABILIZER™ LPG pump package conguration utilizing a pilot operated back pressure regulator, a dierential pressure BV valve, gauges, hydrostats and isolation valves as required.
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LPG Vaporizers An LPG vaporizer heats liquid LPG to the vapor phase� Tis T is helps ensure that only vapor is delivered to the gas supply system or to an SNG Blender� In a small capacity LPG only system, it is possible possible to obtain vapor directly direct ly rom the vapor space o the storage tank� t ank� vaporization� Te energy required to vaporize the liquid Tis process is called natural vaporization LPG comes rom the sun as energy is transmitted through the wetted walls o the tank� Various actors ac tors limit the amount o vapor that can be created in this thi s way, way, including the size o the tank, the temperature dierence between the liquid LPG and the ambient air and the degree o ll o the tank� Typical Waterbath Type Vaporizer
A vaporizer is engineered to convert liquid LPG to the vapor phase� I the vaporizer is part o an SNG system, this th is vapor will then be diluted with air to provide provide a uel that is interchangeable interchangeable with natural natura l gas� In a Waterbath vaporizer, the vaporization process works as ollows: Liquid LPG is pumped into inlet o a waterbath vaporizer’s process coil� Te process coil is immersed in a solution o heated water and glycol� Tis waterbath solution is typically heated to 180 o to 200oF [80o to 93oC] by a gas red burner which also utilizes utilize s the LPG vapor it is creating as its own uel� As the t he liquid liquid LPG passes through t hrough the process coil, it is heated to its its boiling point, point, vaporized and a nd then super-heated super-heated in the last section o the coil� Vapor leaves the process coil by passing through a liquid oat switch assembly� • •
•
•
Te purpose o a vaporizer is to add heat to liquid LPG causing it to boil and become a vapor� Tis process does not increase the pressure in the LPG vapor delivery delivery line� Te reason pressure does not build in the delivery line is that the entire LPG system is pressure balanced� Te liquid delivery delivery line rom the tank, through t hrough the pump and to the vaporizer can ow in both directions — it is bidirectional� Any pressure increase that results rom the added heat rom the vaporizer will ow back to the storage tank as soon as the pressure in the return direction exceed the pressure pressu re in the opposite direction� Again Aga in — this is a pressure balance balance system� Most large (200GPH or larger) vaporizers are gas red wterbth type� Again, Aga in, in this design design
AQUA-GAS® WB-V Series Waterbat h Vaporizer, Vaporizer, ront
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LPG and SNG Systems Overview
the liquid LPG is piped through th rough a water/glycol solution� solution� Tis prevents ree reeze ze ups in the winwi nter — just like with your automobile radiator� Te waterbath is heated to approximately 160 to 200 20 0oF depending on the LPG composition� Te LPG vapor exits the vaporizer vaporiz er with a minimum o approximately 20°F o superheat� Te vaporizer’s gas red burner uses the vaporized LPG as a s its uel source� sourc e� During start-up s tart-up,, even on very cold c old days, there is generally sufcient vapor coming rom the LPG process coil to satisy the burner, allowing it to begin the process o heating the water/glycol solution� Other types ty pes o vaporizers include include steam red vaporizers and electric vaporizers� Direct red vaporizers, which are very ver y uncommon, uncommon, heat LPG in a metal con c ontainer tainer heated directly by ame impingement impingement on the bottom o the container� container� Tis type vaporizer has a poor saety record and a greater greater potential potential or leaks and res than th an other type ty pe vaporizers� Such units are considered dangerous and are not recommended by Ely Energy� There are a number o basic saety saet y limits on a typical t ypical gas red waterbath vaporizer. These usually include: • • • • •
Low waterbath level cuto switch High waterbath temperature switch Low and high gas pressure switch to burner burner Liquid LPG carry carr y over switch Saety relie valve or high pressure LPG in the t he coil (set or or 250 psig)
Typical AQUA-GAS® WB-H Series vaporizer with Optional Maintenance House installed in Peru.
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SNG Blenders Te purpose o an SNG blender is to blend air with LPG vapor rom a vaporizer in the correct ratio to create a gas interchangeable interchangeable with natural natura l gas� As A s you know, know, natural gas g as has a BU content o approximately 1000 BU/Ft3� Undiluted propane vapor has a BU content o about 2520 Btu/Ft3� However, a mixture o about 45% air and 55% propane vapor results in SNG with a BU content o around 1420 Btu/Ft3 and a specic gravity o 1�31� 1�31� So — our SNG has a BU/ B U/t t3 3 content o 1420 1420 versus natural natur al gas ga s at 1000 — Why W hy are they so dieren d ierent? t? Why 1420 BTU/ BTU/Ft Ft 3?
he reason involves the relative specic gravity (weight) o the gases� SNG is approximately twice as heavy as natural gas� ga s� SNG has a SG o about 1�31 1�31 versus natural natu ral gas at about �65� Physics states that the ow o a gas through any a ny orice, orice, (e�g�, a burner orice) is directly proportional to Simplied depiction o SNG and NG interchangeability. the square root o the specic gravity ratio� In our example, the square root o 1�3 ⁄ �65 is the square root o “2” which is 1�41 1�414� 4� So, the heavier SNG ows through a burner bur ner orice more slowly slowly�� You You can think think o the SNG as being bei ng thicker or more viscous then the “lighter” NG� Since SNG ows more slowly, each cubic oot o gas must have a proportionately proportionately higher BU cont c ontent ent in order to make up or the act that less gas g as is owing to the burner! Again, Agai n, the ormula ormula shows us that th at because o the specic gravity dierence, there must be approximately 1�414 times as many BUs in the heavier SNG than in the NG� Types o blenders:
Tere are two basic SNG Blending processes: Venturi Blenders (No air compressor required; can provide 5-12 PSIG o propane/ air pressure) pressure) Prprtinl Blending (Air compressor compressor required; can ca n provide provide whatever SNG pressure is required)
•
•
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LPG and SNG Systems Overview
Venturi Blending Venturi blenders blenders use the kinetic energy in the LPG vapor stream to create the desired mixture� mixtu re� Te theory o operation is similar to a typical ty pical atmospheric atmospheric burner� burner� ExaMPLE:
Te venturi is named ater an Italian physicist: Giovanni Venturi� He observed that when a uid — either gs like LPG or liquid, is passed through t hrough a constricted channel, it it will increase increa se in velocity� velocity� With With SNG venturi systems, this t his occurs occu rs as LPG vapor passes through the throat o the venturi nozzle� During venturi operation, the LPG is gaining kinetic energy� Let’s think or a moment: Due to the First Lw Thermdynmics (“Conservation o Energy”) kinetic energy must come rom some place — it does not just “occur”� I you look up the First Law o Termodynamics Termodynam ics in a reerence book you will wil l learn that th at Hwever, energy cn be cnverted cnver ted rm ne rm energy can be neither created nor destroyed� Hwever, t nther nt her.. For example, ptentil energy can be converted converted to kinetic energy� But, total energy remins cnstnt� In a venturi, kinetic energy increases as the LPG is accelerated� he “pressure” (i�e�, energy) is reduced — and hence total energy again remains constant� Te venturi creates “negative pressure” in the venturi chamber� ch amber� Consequently, Consequently, the atmospheric pressure is “greater” than the pressure in venturi housing� Air ows as we would expect, expect, rom the higher h igher pressure zone z one (atmosphere (atmosphere)) to the lower pressure zone z one (into (into the venturi housing) — to mix with the t he LPG� Tis is a simple explanation, but it describes the principle� 20
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From the previous example it should also be apparent that the 1most energy energy the t he atmospheric pressure pressu re can ca n contribute is about (1) (1) atmosphere or (14�7 PSIG)� PSIG)� You will also a lso notice notic e that as a s the SNG pressure gets higher — the inlet in let pressure to our venturi venturi (the pressure rm ur pumpset) must also increase! Tere are limits li mits on what LPG pressures are easible easible based on vaporization and pumping� In summary, without using an air a ir compressor or blower, Venturis Venturis can provide: 7 PSIGm o SNG pressure i the LPG is ~ 50% butane and 50% propane •
(* this can vary slightly) slightl y) • •
12 PSIGm o SNG pressure i the LPG is 100% propane 6 PSIG m o SNG pressure i the LPG is 100% butane
I we want to increase SNG pressure pressure above these pressures pressure s with a venturi — we must increase the available ir pressure above atmospheric pressure� Tis requires use o an air compressor or blower� blower� Typical Venturi Venturi Blending Blend ing System
1
Technically – this depends on elevation, etc. but or sake o this discussion, this is adequate.
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LPG and SNG Systems Overview
Venturi Blending Operation o the Venturi System
1� A venturi Solenoid Valve is energized by a Pressure Control Switch which senses pressure o the SNG in the SNG Surge ank� 2� Te Pressure Regulator controls the undiluted LPG vapor pressure to the Venturi Nozzle� 3� As SNG rom the Surge ank is consumed by the downstream gas ga s consuming equipment, the SNG pressure in the Surge ank drops� Te Pressure Control Switch senses the pressure o the SNG Surge ank dropping and energizes the Solenoid Valve allowing LPG vapor at a regulated pressure to be ed through the venturi Nozzle and then t hen through the t he Venturi Venturi Chamber� 4� Te LPG Vapor Vapor passes through t hrough the Plenum Chamber between the Nozzle and the Venturi Venturi throat at a high velocity� velocity� A negative pressure is created and this t his inspirates the required volume o air throughout t hroughout the Venturi Venturi throat into the t he expansion section (di (diuser) user) o the Venturi Venturi where the velocity o the mixed mi xed gases are converted to static pressure� 5� Air entering entering the Plenum Chamber passes through t hrough the Inlet In let Back Check Valve� Valve� 6� SNG leaving the Venturi Venturi passes through t hrough the manual ma nual shut o valve and into the SNG Surge tank� 7� When pressure in SNG Surge ank ank rises ris es to its set point, the Pressure Con C ontrol trol Switch opens, thus deenergizing the Solenoid Valve which then closes� 8� Te Inlet Ball Check Valve in the venturi housing prevents escape o SNG back to the atmosphere� 9� Saety limits include a High/Low High/L ow SNG Pressure Limit Switch, Low Input Pressure Limit Switch and the Low Water emperature Limit Switch on the vaporizer� Any o these devices will de-energize the Solenoid Valve on the vapor discharge side o the vaporizer vaporizer and shut down the SNG system�
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Proportional Blending Te AFC™ Te AFC™ proportional proportional mixer provides SNG mix mixtures tures at pressures rom 13 PSIG PSIG to over 150 PSIG in a capacity range rom 38 million BU/HR to 2000 million BU/HR) AFC™ stands stands or Active Flow Con Control� trol� Te AFC ™ can use both ‘eed orward’ orward ’ and ‘eedback’ control or ast response and unparalleled accuracy� In conventional ‘eedback only’ control systems the t he response to an error can only be identied identied and corrected ater a ter the t he event occurs� For example, with a mixing valve type system, a gas quality problem is identied by a calorimeter ater the problem occurs� Ten a correction is attempted� Tis slow reaction coupled with multip multiple le correction attempts then causes c auses more control control oscillations oscil lations and creates urther unstable gas quality outputs� Te AFC ™ eed orward control design eliminates the problem! When the AFC ™ is started, sta rted, the the LPG ow meter sends a ow value to the control control system� Te control system responds instantaneousl inst antaneouslyy and pre-determines the approximate required position o the air ow control valve relative to the LPG vapor ow rate� Within seconds, the actual actua l measured air ow rate is compared with the calculated ow rate and the control system makes the necessary ne adjustments� Te AFC ™ is now on line� Perect gas — no wild swings swi ngs and no “bad gas” typical t ypical o old conven conventional tional mixing valve va lve systems� Te AFC™’s Automatic Load rack racking ing option allows pressures pressu res and ow parameters para meters to be pre-set in the Control System� Mixing with intelligence, the AFC ™ automatically automatically closes the mixed gas ga s outlet valve and then automatically reopens it at a lower lower down stream pressure! No manual manual steps are required and a nd the concern o “turndown” “turndown” is eliminated� Te Flow Schematic Schematic illustrates the basic operation o the AFC ™ Blender� Blender� LPG vapor and comp c ompressed ressed air enter enter the AFC ™ in parallel streams� Flow meters instantaneously and continuously send ow data to the Control System� Te Control System provides both eed orward and eedback control� Te eed orward control constantly calculates the required air to achieve the desired mixing ratio and adjusts the airow air ow control control valve accordingly� Simultaneously, the eedback control loop compares the actual actu al valve (i�e� Wobbe, Wobbe, BU/SCF, BU/SCF, KCAL/Nm3, etc�) o the mixed gas with the desired set-point value and makes any necessary ine adjustments� hese small adjustments compensate or any errors inherently associated with instrumentation� instrumentation�
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LPG and SNG Systems Overview
Proportional Blending Te Human Machine Machine Interace (HMI) (HMI) is a simple ouch ouch Screen Panel provided provided with the the system� A single cable connects with HMI to the AFC™ J-box� Installation Installation couldn’t couldn’t be easier!
AFC Control Panel with Touch Screen or HMI
Single Profbus Cable
Local J Box on AFC
Interior View o Control Panel
1 8
Pressure Regultrs (Not provided)
16
Pressure Indictr (Displays mixed gas discharge pressure)
2 9
Butter fy-type Isltin Vlve 17
3 10
Wer-type Bck Flw Check Vlve
4 11
Pressure Press ure Trnsmitters Trnsmit ters
discharge pressure signal to the control system)
18
Flw Meters
6 13
Temperture Temperture Sensr [RTD] [R TD] (Temperature correction o the fow data)
SNG Dischrge Sety Vlve (Pneumatically opens – spring close; Valve closes when there is a saety violation)
(Pressure correction o the fow data)
5 12
Pressure Trnsmitter Trnsmitter (Provides mixed gas
19
Butter fy-type Isltin Vlve
20
Lcl Eplsin-pr Junctin B (Mounted on the AFC Blender)
7
air Flw Cntrl Vlve (Controls air fow based on fow and control parameters)
21
Prfibus Prfibu s Cble (Single cable link rom the AFC Junction Box to the Control Panel)
14
LPG Vpr autmtic Sety Vlve (Pneumatically opens – spring close; Valve closes where there is a saety violation)
15
24
22
Cntrl Pnel (With “Touch Screen;” Operator-riendly and compact)
Turbultrs (Internal to header)
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Piston Type Blending System Operation
Modern Modern gas blenders blenders such as the t he AFC™ Blender Blender have no moving parts� Te design uses highly high ly accurate ow meters and a sophisticated sophisticated but simple to use Human Machine Mach ine Interace (HMI)� However, there is another type o mixer – the piston, or oating orice type� Even Even today piston type mixers mi xers are still stil l sometimes used, especially outside the USA and Europe� Te old ashioned piston mixing valve design date rom the late 1940’s� Te basic mixing valve design utilized a piston, a sleeve and some type o cast or abricated valve body� Te air and LPG vapor enter the “mixing chamber” through “ports” cut in the valve bodies� Depending on the manuacturer, the sleeve (i�e� cylinder to the piston) either used rotational movement or is stationary� As or the piston, it had either vertical movement, or a combination o both vertical and rotational depending on the design� Mixing valve va lve type mixers mi xers were “ported” “ported” to admit gas ga s and air at the relative proportions proportions required at a ow rate� Te piston moved vertically inside the sleeve – sometimes by a diagram located below the piston that senses the t he line pressure� Rotation o the sleeve (or the piston in other designs), allowed the proportions o gas and air to change as the exposure o the port inlet increased or decreased in size� siz e� Tis rather r ather primitive primitive method o ratio adjustadjustment ormed their basis o their mixing control� Like any piston and cylinder design, this style o mixing mixi ng was a total totally ly mechanical process� However, However, contamination contaminat ion rom the LPG, or example the C5’s, C5’s, oils and so called ca lled heavy heav y ends made this difcult and potentially dangerous� LPG is laden with contaminants� Dirt and heavy ends rom the LPG built up and on occasion eectively “locked” the mixer� When that occurred, oc curred, the cylinder and piston stuck together! Some gas utilities reported perorming maintenance on their old old mixing valves va lves every day or 3-4 times t imes a week! It is also important to understand that LPG-air mixing valves were typically slaved blenders� Tat means the air and a nd gas side o the system were pneumatically pneumatical ly “slaved” to each other� Te perormance o one side dictated the perormance perorm ance o the other� Consequently, they did not maintain the same mixing ratio at all ow rates� Tis resulted in substantial gas quality qua lity variations variations depending on ow rate� Sleeve and piston type blenders operating at lower ow rates tended to produce lean (lower ( lower Wobbe values) mixtures compared to the Wobbe at higher ow rates� Tis was potentially dangerous with negative impact on end users o the gas� Te caloric value deviated dramatically rom set value when ow dropped below 15 % o their rated capacity�
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LPG and SNG Systems Overview
At lower ow rates (e�g� 10%) the mixing ratio could go out o control! Auto-Ratio-Control, a standard unction on most modern mixers, is not standard on the old piston type mixer� For the pistons types, the Auto-Ratio-control is an option� Te option option typically ty pically involves adding an awkward and sometimes problematic problematic servo ser vo motor motor to rotate the piston or sleeve in an attempt to control the Wobbe� With this design, the servo motor receives a signal rom a gas quality instrument and attempts to adjust the output o the gas quality by rotating the port on the mixer� Tis type t ype control is inerior in response time and accuracy accur acy�� Piston to sleeve aces must also be machined (oten by hand) to as precise to its original shape in order to operate properly� Care must also be taken regarding corrosion problems that might severely aect piston-sleeve piston-sleeve aces� Carbon Ca rbon dioxide can readily cause c ause an acid to orm in presence o water or humidity humidit y in both the LPG LPG vapor or air supply� supply� Given the quality o most LPG, avoiding a build bu ild up rom parafn’ para fn’ss and bituminous bitumi nous ends is impossible� Tis type ty pe build up leads to sticking sticki ng o the piston in the sleeve� Several Severa l documented cases case s occurred where the vertical shat sh at or piston piston rotation and adjusting adjusting the t he gas air a ir ratio have broken broken rom the torque o the Auto-Ratio-Control systems� systems � Te piston gets locked by the impurities, but the Auto-ratio controller controller continues continues to rotate the shat sha t – nally nally the shat sha t simply breaks� I you encounter this type o a mixer at a location, we strongly suggest you attempt to contact the manuacturer� As about hal the US manuacturers o this design are now out out o business, you may encounter difculty� Feel ee to contact Ely Energy service with questions� Most important importa nt – be cautious and do NO operate the device i you lack knowledge or experience� Inoperable old style piston blending system that was removed rom service in 2003 .
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SNG to NG Tie-In
Te connection o any SNG system to a natural gas g as distribution dist ribution line (i�e�, (i�e�, tie-in) tie-in) is made downstream rom the client’s metering and pressure regulating equipment� Tere are two choices in selecting the pressure at which wh ich the SNG is delivered� I the SNG mixture mixt ure is delivered at at a pressure below the natural gas g as delivery pressure, the natural gas ga s system must be isolated with a valve in order to use the SNG� I the SNG is delivered at a pressure above the natural gas delivery pressure, the SNG will automatically replace the natural gas in the distribution system� Tis happens because either the check valve installed instal led in the natural natura l gas piping piping or the utility’s regulator stops the ow o natural gas� In this case, no valves need be closed at the connection between the SNG and natural gas piping� An additional advantage o this arrangemen a rrangementt is that th at i the SNG system shuts down or any reason, the natural gas will automatically begin to ow when the SNG pressure alls below the natural gas delivery delivery pressure�
The tie-in o t he SNG to the NG piping requires expertise and knowledge o both the NG and the LPG system. As with all work associated with hazardous uels and materials, we recommend such work only be done by appropriately trained and licensed proessionals.
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LPG and SNG Systems Overview
Properties of LPG LPG is dierent rom the liquids and gases people typically encoutner� Tese unique properties can be dangerous i not understood� Caution is required! Te ollowing properties must be understoo u nderstood d in order to avoid avoid unsae actions regarding an LPG system� The boiling point o propane is -44°F.
LPG is stored in pressure vessels� Unlike water, LPG boils at a temperature well below common ambient temperatures� Tis means that anytime LPG liquid is released rom a pipe or container and exposed to common atmospheric pressure and temperature, the liquid will boil and convert convert instantly inst antly to vapor� vapor� Several saety issues arise when LPG liquid is released: •
•
• • •
When LPG converts to vapor, it expands 270:1 times its liquid volume� Tis will displace air and potentially potentially becoming a breathing hazard as the t he air is pushed away! Liquid LPG will boil! Remember, propane’s boiling point is -44°F� At this temperature it will cause c ause instant rostbite to any exposed skin� Heavy vinyl gloves with cus cu s should be worn� A ace shield sh ield or eye protection protection is also required� s urces wy. Te LPG vapor cloud is an explosion explosion hazard� haza rd� Keep ny nd ll ignitin surces Any remaining liquid will continue to boil, converting into more vapor� Liquid can travel some distance when released released — be careul! care ul!
When LPG liquid is released, the conversion rom liquid to vapor rerigerates the air it comes in contact� A white cloud oten orms� Tis white cloud is actually rozen water vapor in the air; air ; this thi s is not LPG liquid or LPG vapor� Te cloud’s presence can indicate the t he approximate location locat ion o the vapor cloud� However, do not rely on the presence or lack lac k o a cloud to judge the potential danger rom LPG in the vicinity� LPG has a low fammability limit.
We describe the mixture o air and LPG needed or combustion in terms o ammability limits� A ammability limit lim it is simply the percentage percentage o LPG needed in an LPG/air LPG/air mixture mix ture to support combustion� Normally Normal ly,, this value va lue is given in both upper and lower limits o ammability� Te upper limit is the percentage o gas ga s in the t he richest (most gas rich) mixture mixtu re that will wi ll support support combustion� Te lower lower limit is the percentage o gas in the leanest (least gas rich) mixture that will support combustion� Reer to the ollowing table or limits o ammability o LPG�
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FlaMMability liMitS (Fuel in air)
* Note that a concentration o only 2.15% 2.15% propane in air a ir will create a fam mable or explosive mixture. This limit is hal the lower limit o natural gas.
ProPane
nat ur al ga S
u
9.6 %
15%
Low
2.15 %
5%
LPG is both odorless and colorless� colorless� Because o its hazard haza rd as a ammable am mable material, material, saety codes require an a n odorant be added to LPG sufcient to be detectable at 20% o its lower lower ammabilit am mabilityy limit� Te presence o the odorant suggests sugg ests the t he presence o LPG, but does not not indicate its concentration� concentration� I LPG has ha s passed through soil or placed in a new container or pipe, the odorant could be signicantly stripped rom the LPG� When W hen checking or possible leaks rom rom underground piping, piping, a detector sensitive to LPG must be used� Never rely only on your sense o smell! Substantial underground leaks can develop with little or no odor apparent� LPG vapor is heavier than air. ai r.
Always remember remember that LPG vapor is heavier than air� a ir� I a leak develops in an LPG line or container c ontainer,, the LPG vapor will settle set tle in low areas and can become concentrated, concentrated, particularly part icularly i there is litlittle or no air movement� Tis trait is important to know and understand when trying to identiy the source o a leak, or working in an area where a leak has occurred� I a leak originated originated with a liquid release, release, the rerigerating eect o the conversion to vapor will wil l also tend to make LPG vapors sink� Te weights o gases are ccompared ompared using specific grvity� Te specic gravity o a vapor is the comparison o the weight o a given volume o a gas at a certain temperature temperature with the t he same volume o air at the t he same temperature temperature and pressure� LPG vapor has a specic gravity o 1�50 at 60° F�
NaTURaL GaS
aIR
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LPG and SNG Systems Overview
Codes and Standards Codes and standards have been developed to promote saety in the operation o many activities� activities� Plumbing, electrical electrica l and building codes are a re a ew examples� For LPG equipment, equipment, the primary resource is the Ntionl Fire Protection assocition Pmphlet 58 (NFPA 58)� NFPA 58 covers the storage and handling o Liqueed Petroleum Gases and reerences a number o other codes or standards� Te three major components o the code are: Equipment design Equipment Equipment installation inst allation Operating procedures • • •
EEI recommends reviewing NFPA 58 and maintaining a copy c opy at each acility with LPG L PG equipment as a reerence� NFPA also publishes a ‘Handbook’ ‘Ha ndbook’ in conj c onjunction unction with wit h Pamphlet 58� Te handbook includes many descriptive passages passage s to help interpret the code and is also als o a recommended reerence� Chapters in NFPA 58: CHaPTER
30
TITLE
DESCRIPTIoN
1
Generl Prvisins
Defnitions, scope, etc.
2
LP-Gs Equipment nd applinces
Standards or tanks cylinders, valves, piping, and appliances (i.e., vaporizers)
3
Instlltin LP-Gs Systems
Guidelines or installing equipment in bulk plants, cylinder flling stations and on industrial and road vehicles
4
LP-Gs Trnser
Guidelines Guidelines or flling tanks and c ylinders
5
Strge Prtble Cntiners awiting Use r Resle
Includes scope, general provisions, storage, and fre protection
6
Vehiculr Trnsprttin LP-Gs
Includes scope, transportation modes and parking and garaging vehicles
7
Buildings r Structures Husing LP-Gs Distributin Fcilities
Includes scope, separate and and attached struc tures
8
Engine Fuel Systems
Application, general purpose and industrial vehicles, engine installation and garaging o vehicles
9
Rerigerted Strge
Containers, impoundment and locating aboveground containers
10
Mrine Shipping nd Receiving
Piers, pipelines, and actions prior to transer
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LPG Safety Components Saety Valves
Tere are a number number o types o saety valves used on LPG systems Back Flow Check Valve
Te back ow check valve, also called ca lled the back check or just check valve, unctions u nctions to permit the ow o LPG in only one direction through piping� With no ow or ow in the reverse direction, the valve closes by spring pressure or system pressure on the back o the valve disk� When ow in the proper direction is sufcient to overcome the combination o spring orce and the weight o LPG on the other side o the valve disc, the valve va lve opens� Tis valve va lve is used where ow is normal normally ly in one direction only and protection protection is desired rom ow in the opposite opposite direction; i�e�, i�e�, the ll opening into the storage tank� tank � Excess Flow Valve
Excess Excess ow valves prevent prevent the catastrophic catast rophic loss o product in the event o o line breakage� breakage� Excess ow valves are used where the normal ow is in the same direction direct ion as the protection is required� required� Should any connecting line become damaged dama ged or broken, broken, any leakage created in excess o a designed quantity, quantity, will wil l cause the t he Excess ow valve to close� Tis prevents the possibility o losing the entire contents o a container� A common applicatio application n o this type t ype o valve is the process opening in the storage tanks� tank s� It is important to remember that tank valves should be ully opened in order to allow the excess ow valves to perorm as designed� I a tank valve is not ully opened it could provide provide a greater restriction than the t he setting o the excess ow check valve, thus preventing preventing the excess ow check valve rom operating as designed� Note the excess ow valve is not normally designed desi gned as a positive shut o valve� valve � When the valve closes closes as a result o ow above its design ow, ow, a small weep hole remains open allowing al lowing an eventual equalizatio equaliz ation n o pressure i the excess ow was caused by opening a downstream valve too ast and not a line break� When W hen the pressure on either side side o the valve equalizes, equalize s, the valve will open and be ready again� Pressure Relie Valve
Te pressure relie valve is possibly the most important valve installed installed in an LPG installation� insta llation� It is designed specical specically ly to protect protect tanks tanks or cylinders rom over over pressure� I this th is valve cannot perorm its unction properly, the tank or cylinder could rupture� Although all a ll pressure relie valves perorm similar unctions, certain types have eatures and characteristics that t hat uniquely uniquely aect their t heir capacity, capacity, selection, selection,
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LPG and SNG Systems Overview
LPG Safety Components and use� For this th is reason, pressure relie valves are separated into dierent types� Each pressure relie valve has special markings that provide inormation about its size and capacity� capacity� For example, all pressure relie valves are a re marked with a pressure rating� Tis rating indicates the pressure at which the valve will wi ll start star t to open� I a pressure relie valve with the t he wrong pressure rating is installed instal led in a tank or cylinder, cylinder, high pressures could build up inside the container and the valve could relieve prematurely� Every Every pressure relie valve must be careully sized and a nd matched matched to a particular particu lar type t ype and size o container� NFPA 58 species how to properly size a relie valve� Hydrostatic Relie Valves
LPG expands dramatic dr amatically ally with a rise in temperature� It can exert excessive orces on pippiping, valves and other equipment i trapped between closed valves� Hydrostatic relie valves are thereore installed where liquid liquid LPG can be trapped t rapped between two valves� Hydrostatic relie valves are simple in construction� At the bottom o the valve body is a threaded inlet port� Te valve screws into a tting on the system to be protected� Inside the valve body, a spring held in place by a vented retainer presses down on the poppet at the bottom o the valve� Te valve poppet is tted with a sot seat disc made o a synthetic material to ensure it orms a tight seal against aga inst the inlet port� Under normal conditions, the orce exerted by the spring holds the valve poppet down (closed) over the inlet port so no LPG can escape through the valve� I expansion o the trapped liquid liquid causes the t he pressure in the valve inlet to rise above its preset setting, the pressure orces the poppet o o its seat and releases release s a small amount a mount o LPG into the atmosphere through the vent in the retainer at the top o the valve� Tis quickly relieves the excess pressure in the system s ystem and the spring again ag ain orces the t he poppet poppet back over the inlet opening, reclosing the valve� Hydrostatic relie valves should be tted with rain caps to prevent moisture and debris rom accumulating accumulating inside the valve� va lve� It is also a good practice pract ice to provide a vent stack or pipe pipe away or hydrostat hydrostatic ic relie valves� Tis is important i mportant or Hydrostats located in low lying areas area s or where discharge rom the valve might impinge on sources o ignition� Emergency Shuto Valves (ESVs)
Excess ow check valves va lves have been used to prevent large LPG spills at transer tra nser points� Tese excess ow valves are installed at a point where the hose joins the rigid piping system� In the event a hose is sheared o completely, completely, the excess exces s ow valve will wil l slug shut� Tis can prevent a major spill o LPG� In certain situations, however, an excess ow valve may not close properly� Even when an excess ow valve closes properly, LPG will continue to discharge through the equalizing orice� I the t he spill is ignited, the resulting re
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may prevent the operator rom closing the manual shuto valves upstream rom the break in the hose�
Combustion characteristics of LPG Combustion is a chemical reaction that changes a fuel source into a different form of energy — heat. heat .
Tree ingredients needed to start and sustain susta in combustion are: uel, oxygen, and an ignition source� All three must be present in the proper proportions or combustion to occur� Te combustible molecules molecules in LPG are a re hydrocarbons� Hydrocarbons are chemical chemica l compounds consisting o hydrogen and carbon atoms� Te oxygen needed to burn LPG vapor is obtained rom the air� Air is made up o 20% oxygen, 79% nitrogen, and about 1% o other miscellaneous gases� Te ignition ignition source must provide provide enough heat to the mixture mixt ure o uel and oxygen to raise the temperature o the LPG to its ignition temperature, which is between 920 oF — 1,120 oF� Combustion Ratio
Te combustion ratio is the ratio o air to uel� A ‘perect’ ratio exists when all o the hydrogen and carbon combine with air and no oxygen or uel is let over during combustion! Tis is called the stoichiometric ratio� For LPG the stoichiometric ratio is 23�9:1 and or Natural Natura l Gas 9�6:1� 9�6:1� LPG will wi ll burn anytime anytime at a ratio o 2�15% 2�15% to 9�6% 9�6% LPG in air a ir exists� ex ists� However, However, or proper combustion in appliances, a ratio approaching the stoichiometric ratio is required� When LPG and air burn in the correct ratio, complete complete combustion combustion occurs� Since LPG is a mixture o hydrogen and carbon, water vapor and carbon dioxide are combustion by-products�
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LPG and SNG Systems Overview
SNG System Operation Basic Saety Precautions
Tese are basic procedures or operating your system saely: Do not perorm any actions which you have not been trained Be very deliberate about about any actions you you take, think t hink them through! th rough! I need to know about aspects o the system (valve positions, etc) prior to perorming a unction u nction,, check them t hem out personally Read and be amiliar with your operating manuals Be amiliar ami liar with any pertinent emergency emergency procedures Keep the system maintained Repair any non-unctioning or damaged components promptly Remember Remember that an a n empty empty tank ta nk is no less dangerous than tha n a ull one Remember Remember that th at most accidents happen during transers o LPG L PG
• • •
• • • • • •
Operating Manuals
Operating manuals should include the ollowing sections: Startup to standby st andby procedure procedure Standby to operating procedure Operating to standby sta ndby procedure procedure Shut down procedure roubleshooting procedures
• • • • •
Receiving LPG
Te most important aspect o receiving LPG is knowing in advance i you have sufcient tank capacity to accept the anticipated load� Maintenance
General annual maintenance requirements: requirements: Check or any visible damage Check all valves va lves or easy operation Remove weeds and other combustible combustible hazards rom the area est or corrosion corro sion Check entire system or leaks and a nd correct Check re extinguishers est and a nd document operation operat ion o Emergency Shuto Valves • • • • • • •
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SNG System Maintenance Requirements TTU • • •
Check gaskets, seals, and sealing suraces Check condition condition o caps and replace i necessary necessar y Check operation o Emergency Shuto Valve
Tank • •
Check condition o paint Check condition condition o pressure gauges and temperature gauge
Pump • • •
Check or seal leaks and a nd piping piping leaks Check condition o pressure gauges Open strainer valve and a nd check or the presence o water
Vaporizer • • • •
Check condition o gauges Check condition condition o glycol mixture; mixtu re; pH maintenance is critical Check or any leak leakss Check to ensure saety devices work
System Malfunctions and Emergencies How to Identiy Problems •
• •
Be amiliar am iliar with w ith equipment equipment when operating operating and not operating Note the typical temperatures and pressures shown on gauges. Listen or leaks and other unusual sounds Look or visible damage
How to Check or Ammonia in LPG
Some LPG dealers use their vehicles to transport ammonia during the summer and LPG during the the winter� Contam Contamination ination o LPG by ammonia is possible� I you you suspect the t he presence o ammonia, test by wetting a piece o red litmus paper in distilled disti lled water and exposing to LPG vapor or 30 seconds� A blue color indicates the presence o ammonia�
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LPG and SNG Systems Overview
System Malfunctions and Emergencies How to Recognize Combustion Problems
An SNG standby system creates a mixture mixtu re o LPG and air compatible compatible with natural gas� ga s� When W hen a compatible compatible mixture mixt ure is created, it will be difcult di fcult or the untrained observer to determine whether an appliance is burning natural gas or SNG� With the higher carbon ca rbon content, content, SNG will tend to have slightly more yellow in its ame� Appliances burning natural gas must be tuned to create proper combustion� With natural gas, the t he limits o ammability range r ange rom 5% to 15%� 15%� Te limits o ammability o LPG are 2�15% to 9�6%� As a result, a natural gas appliance can be out o tune and still burn, but when supplied with a perect SNG mixture can be out o tune� Te best method to handle ha ndle apparent combustion problems problems is to rst tune t une the appliance on natural gas� Ten switch uels to SNG or conrmation� Most combustion problems can be addressed in this t his manner� I problems problems still exist, exis t, it is possible that the mixture mixt ure generated generated by the SNG system does doe s not have the correct correc t Wobbe Wobbe index� It is either too lean or too rich� When the mixture mixt ure is too lean, appliance appliance burners will ash back or pop� A rich rich mixture mixtu re will appear yellow or with sooting� Te SNG must be adjusted to provide the optimum combustion match match with natural gas� ga s� One appliance which seems seem s to have more more problems than most is the high hig h intensity inrain rared heaters� Tese devices mix all the t he air required or combustion combustion at the burner rather than depending on secondary secondar y air or complete combustion� Tey operate at the edge o the capability o the burner Venturi to entrain the correct amount o air� As a result they are very sensitive to the delivered gas pressure and the plant air pressure� Proper operation by inrared heaters may require individual adjustment o gas pressure and air shutter� Most Common Minor Problems •
•
36
Leak s are probably the most common common SNG system problem� problem� Leaks Leak s in gas Leks. Leaks lines and components impact saety, operational capability and plant economics� An air leak o sufcient sufcient volume can impact measuring or controlling loops and may compromise compromise saety o the system� Wter in LPG. Water Water is a contaminant c ontaminant in LPG� It can seriously s eriously interere interere with the t he proper proper operation o o pumps and regulators� I water is suspected, a ‘reeze o’ o ’ test can c an be perormed to determine the t he presence o water� water� In cold climates, i water is present in concentrations concentrations o more than tha n a ew parts per million, corrective action must be taken� Larger L arger concentrations concentrations can ca n result in liquid water collecting in low points in the system� Te remedy or water in the LPG is addition o methyl alcohol (methanol)� Te easiest method to introduce methanol is to request its inclusion rom your LPG supplier in your next LPG order� Add a maximum maxi mum o 20 gallons o methanol methanol to an 18,000 18,000 gallon ga llon tank and a maximum max imum
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•
•
• •
o 30 gallons to a 30,000 gallon tank� Leking Pump Sels. Pump seals are a common problem� Check the pump requently quently or signs o leakage leak age or excessive exces sive wear� Temperture Temperture nd Pressure Pressu re Cntrls. All contro c ontrols ls are subject to damage and require calibration checks� Burner cntrls. Check or proper operation� leaks� s� Venturi check vlves. Check or leak
Typical Accidents Accidents and How H ow to Avoid Them Pull-away
Te most common accident is a truck pulling away rom an unloading station without disconnecting the hoses� Upgrade your your U U to current c urrent code� Use LPG vendors vendors with trained t rained drivers� • •
Hose break •
Check hoses at requent requent intervals or damage dama ge and leaks�
Accidents at cylinder ll stations •
rain operators well and only allow trained operators, operators, rom a certied training tra ining program, to ll cylinders�
Pump seal ailure •
Check pumps or leaks and wear regularly� regularly�
Non-Standard Situations
A “non-standard “non-standard”” situation exists when equipment equipment is not operating operating within its normal parameters� A hazard thus exists ex ists which is easily contro controlled lled or sel controlling� controlling� Tis hazard haz ard is limited in scope and can be controlled without endangering lives or signicant property� Examples o Non-Standard Situations Include: Prcess pump sel ilure. Fllw these steps:
1� 2� 3� 4� 5�
Notiy appropriate supervisor or personnel� urn o electrical power to the pump motors� Close the pump inlet and discharge valves� Close all tank valves� urn o all operating electrical equipment to prevent ignition o leaking gas�
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LPG and SNG Systems Overview
Lrge liquid r vpr dischrges t truck unld re (n fire invlved).
1� 2� 3� 4�
Notiy appropriate supervisor or personnel� Assist any person in the plant to move move away rom the hazardous haza rdous area� I possible shutdown all operating electrical equipment by tripping main breaker� When sae to do so, isolate the LPG source eeding the leak�
General Precautions in the Event o a LPG Leak, Spill, or Discharge
Because LPG is ammable a mmable,, everyone involved involved with its handling ha ndling must know and ollow re prevention prevention rules� An A n LPG re is one hazard haza rd that everyone wants to avoid� avoid� Any re, large or small, has the potential to destroy property and take human lives� As a result, general re prevention rules and general re precautions in the event o a LPG leak, spill, or discharge, are topics that must be considered everyday when working with LPG� L PG� Te only way to reduce this chance c hance is to be aware o re hazards ha zards and a nd always ollow ollow re prevention prevention rules�
Emergency Procedures Denition o Emergency Incident
An A n “emergency” “emergency” condition exists when extraordinar extra ordinaryy procedures, equipment, equipment, manpower and supplies must be employed to protect lie and property� Tese hazards may include: Overpressure in the system� Large volumes volumes o uncontrolled escaping gas� Fire or explosion, etc� Any leak considered hazardous� Te endangerment o continued sae operation o a major segment o the system; Natural disasters such as oods, hurricanes, hurrica nes, earthquakes or other severe orces orces o nature which make emergency provisions provisions necessary necessar y� Civil disturbances disturba nces or riots which require special procedures� • • • • • •
•
An emergency emergency manual ma nual cannot ca nnot possibly possibly address every situation situation arising and a nd it is thereore incumbent on each employee to become amiliar with: Physical Physical and chemical properties o LPG� Saety procedures and equipment� equipment� Current codes and standards� Operating procedures or all al l installed insta lled equipment� equipment� • • • •
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as is the cse with ll potentilly hzrdous fcilities, public sfety must be given the gretest considertion. Te important importa nt point to remember remember about LPG res is the t he only eective way to
put out a LPG re is to cut o the supply o gas to the ame� I the ame is extinguished beore the gas supply is cut o, the gas can spread to a much larger area� I the re then reignites, it can easily create a much more serious problem� I the gas cannot be turned o without personal injury injur y then let itit burn until re-ghting re-ght ing personnel arrive at the scene� Te main concern in any re caused by or involving LPG should be to prevent injury� Some precautions that should be ollowed are listed below. “Golden Rule” o handling ha ndling emergencies� emergencies� D Nt Pnic. Tis is the “Golden • •
•
•
•
Move Move upwind rom the re re as quickly as possible� possible� Tis will help to avoid avoid burns rom radiant heat� I the re is i s caused by LPG, move all people people in the area a rea to a point at least 1,000 1,000 eet upwind rom the re� Immediately call the local re re department and the companies companies to notiy them o the re as soon as everyone e veryone is saely clear clear o the area� area � Be sure to report the exact location o the re and, i possible, the extent o the damage� I it is possible without danger to personnel, spray water on the vapor space area o the container to keep it cool�
I the re is at the loading bulkhead, go to the nearest remote emergency shuto valve control control that is upwind nd wy rom the re and close the emergency shuto valve� Remember: Do not move to n re downwind of lek or fire or into ny re where you my become trpped r hve n upwind escpe rute.
I there is a small re caused c aused by another ammable ammable material, extinguish the t he ame with a dry dr y chemical re extinguisher� Remember Remember to approach the re rom upwind� How to Spot System Malunctions •
• •
Be amiliar ami liar with equipmen equipmentt when running and a nd when not not running� runni ng� Note the typical ty pical temperatures temperatures and pressures shown on gauges� Listen or leaks and other unusual sounds Look or visible damage
Thank You Tanks Tank s or taking the t he time to read this booklet and or being interested� interested� When we can help — call us� We’re dedicated to serving your needs�
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LPG and SNG Systems Overview
Percentge Prpne in n SNG Miture vs. Dewpint
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Percentge Isbutne in n SNG Miture vs. Dewpint
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LPG and SNG Systems Overview
Percentge N-Butne in n SNG Miture vs. Dewpint
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Dew Pint Dt r SNG with 100% Butne Blended with air L-Pressure
) C ( e r u a r e p m e t l
l-Pss l-Pss (_) (_ ) FoR REFERENCE oNLY – nt r design use! Cntct Ely Engineering
Dew Pint Dt r LPG with 33% Prpne nd 67% Butne Blended with air L-Temperture
) C ( e r u a r e p m e t l
l-Pss l-Pss (_) (_ ) FoR REFERENCE oNLY – nt r design use! Cntct Ely Engineering
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LPG and SNG Systems Overview
Pressure-Temperture Digrm r Vrius Prpne-air Mitures
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Vrius LPG Cmpsitins: Vpr Pressures Typicl Butne-Prpne Mitures
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LPG and SNG Systems Overview
Thermdynmic Prperties Sturted Prpne
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Thermdynmic Prperties Sturted Butne
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LPG and SNG Systems Overview
Physicl Cnstnts Hydrcrbns
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Physicl Cnstnts Hydrcrbns
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LPG and SNG Systems Overview
Vpriztin Rte rm 30,000 Glln Tnk
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Pressure Cnversin Tble
A) Example: 16 psig Converts Converts to 1.17 1.17 kg/cm 2 B) Example: 6 kg/cm 2 Converts to 85.3 psig
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LPG and SNG Systems Overview
Prpne Vpriztin Rtes t 0° F t Vrying Tnk Levels
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Typicl LPG/air Cnsumptin Prfile r City Distributin Grid with 100% Cnnected Ld
Typicl SNG Cnsumptin Prfile r City Distributin Grid with 10% Cnnected Ld
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LPG and SNG Systems Overview
Electric Currents r Specific Cuntries
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Temperture Cnversin Tble
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11385 E. 60th Place So. Tulsa, Oklah O klahoma oma 741 74146 Phone: (918) 250-6601 Fax: (918) 254-5412 Visit us at: at : www.elyene w ww.elyenergy.co rgy.com m Email: sales@elyenergy.
[email protected] com Copyright 2008 – Ely Energ y, Inc. Publication: SNG/LPG Overview 10-08
