GPA RB-194-1994 Tentative NGL Loading Practices《试验性液化天然气装载实践》.pdf

1、 GPA RB-194 94 3824699 OOlbbb1 587 W GPA Reference Bulletin 194-94 TENTATIVE NGL LOADING PRACTICES RB-194-94 Approved as Reference Bulletin 1994 Gas Processors Association 6526 East 60th Street Tulsa, Oklahoma 741 45 GPA RB-394 94 382LI699 O036662 413 TABLE OF CO NTENn Eis Disclaimer . 3 Introductio

2、n and SCO pe . 3 Description of Products 3 Definitions 4 Measurement . 4 Layout and Spacing . 5 Equipment and Installation Siandards 5 General Design Consideratiom 7 Training of Personnel . 8 Carriers Responsibility 8 dorization 8 Product Specifications and Testing 8 Loading and Unloading Procedures

3、 8 Specific Considerations for Volume Transfer Systems 15 Specific Considerations for Weight Transfer Systems . 15 Safety 16 Bibliography . 18 2 GPA RB-194 94 W 3824699 0036663 35T GPA publications necessarily address problems of a general nature and may be used by anyone desiring to do so. Every ef

4、fort has been made by GPA to assure accuracy and reliability of the information contained m ils publications. With respect to particular circumstances, local, state, and federai laws and regulations should be reviewed. It is not the intent of GPA to assume the duties of employers, manufacturers, or

5、suppliers to warn and properly train employees, or others exposed, cmceming heaith and safety risks or precautions. GPA makes no representation, warranty, or guarantee in connection with this pubiicatim and bereby expressly disclaims any liability or responsibility for loss and damage resulting from

6、 its use or for the vioiatim of any federai, state, or municipai regulation with which this publication may conflict, or for any infringement of letters of patent regarding apparahis, equipment, or method so covered. This reference bulletin presents suggested safety practices and procedures pertaini

7、ng to the loading and unloading of NGL (Natural Gas Liquids) at gas processing plants, refineries, tank farms, and marine and pipeline terminais. Many existing codes, standards, regulations, and safety practices, as employed by a cross section of the indusq, have been used in preparing this document

8、. This reference bulletin is not intended to be a code or standard for loading or unloading procedures, or for NGL facility design, but is intended to be a guide for installations where the loading or unloading of NGL is performed. Included in this reference bulletin is a bibliography containing ref

9、erences to material that pertain to the design and operation of NGL installations. Although several states have regulations pertaining to the transfer of NGL into or out of tank tnicks, tank cars, and barges at loading facilities, references to individual state regulations have not been included. Th

10、e bibliography is referenced by numbers placed at the end of various paragraphs. DESCRIPTTON OF PRO DUCE NGL as used in this reference bulletin shall mean and include any product which is composed predominantly of any of the following hydrocarbons, or mixtures of them: propane, propylene, normal but

11、ane, isobutane, butylene, isopentane, normal pentane, and hexanes-plus. Quantities of ethane and ethylene may also be present. (36) 3 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. DEFINITIONS - Liquefied petroleum gas; also known as LE. This material is predominately propane or butane, separately o

12、r in mixtures, which is maintained in a liquid state under pressure within the confining vessel. Driver-attended loading - The loading procedure wherein the driver of the transport truck loads the NGL from the seliers equipment into the tank truck. Volume mfer system - A system wherein the loaded NG

13、L is measured by volurrie, usually in gallons. Ticket-printins meter - A volume meter which issues a “ticket“ containing information, including the identity and quantity of the material being transferred. Temuerature -comDensatd - Refers to a volume meter which measures the volume and automatically

14、corrects the volume to 60OF. Meter proving - A procedure for checking the accuracy of a meter. Overfilling - A load which exceeds the safe maximum volume for a particular material. The maximum filling volume allots space for expansion of the liquid caused by an increase in product temperature. Overl

15、oad - A load weighing more than that permitted by regulation or equipment raLing. Preset de vice - A device that allows a predetermined volume or weight of a product to be loaded on a transport truck. Permissive loading - Loading which is allowed or is initiated by an identifying key or card. Interl

16、ocks - Arrangements of electrical and/or mechanical equipment that prevent bypassing programmed steps, thereby ensuring a safe, permissible procedure for loading NGL from the sellers equipment. Static bonding - The electrical system permitting the dissipation of static electricity that may be contai

17、ned on the transport truck or generated by the loading procedure. Intrinsicallv safe - Safe because of its inherent characteristics or properties, as defined by the National Electrical Code (NEC). (20) Time delav - A device that delays a desired action for a finite period of time, thus delaying acti

18、on on conditions that may be self-correcting. 15. 16. 17. 18. 19. 20. 21. SDraV loaded - A system wherein the product being loaded is sprayed into the top of the tank to condense vapors within the iank. Excess flow valve - A fail-safe valve that prevents the flow rate from exceeding a preset maximum

19、. wine device - The equipment used to determine the level of liquid within the tank. Positive disdacement meter - A meter that determines volume by measuring the actual displacement volume of the liquid transferred. Weight pansfer system - A system to measure the loaded NGL by weight, usually in pou

20、nds. Total weight indicator - An accessory, either of the dial or optical projection type, that is usually incorporated in the ticket printing assembly. Printing register - A register used in conjunction with a transfer system which issues a ticket containing information that includes the identity a

21、nd quantity of the product being transferred. MEASUREMENT All measurement devices should be installed, operated, and proven in accordance with the API Manual of Petroleum Measurement Standards. A. TRUCKSCALES Platform scales may be used to weigh trucks before and after loading or unloading, using th

22、e difference in weight to calculate the volume transferred. 1. Ticket however, they are not normaily used for tank truck or tank car loading or unloading. (16,35) CONTAINERS Each cargo container should be equipped with temperature and pressure gauges. (14) Good spacing is essential for traffic contr

23、ol and control of emergencies. Facilities should be constructed entirely of noncombustible maierials. Proper drainage of the area is also important. A. MINIMUM DISTANCE F2EQUIEMENTS NGL loading and unloading facilities, including marine temiinal and barges, should be located with respect to other fa

24、cilities in accordance with applicable standards, niles, and regulations.(lO, 23, 29,30,33) B. TANK CAR LOADING RACK LAYOUT Tank car loading racks should be designed to meet local, state, and federal agency requirements and in accordance with raroad and industry standards. The layout must be level a

25、nd should provide optimum ease in positioning tank cars. The majority of tank cars in NGL service are 44 to 67 feet long. A suggested layout would provide loading spots on 67 foot centers with a vertical clearance from the track of not less than 22 feet and a horizontal clearance from the center of

26、the track to the edge of the loading rack of not less than 8 feet, 6 inches. (10,29,30) C. TRUCK LOADING RACK LAYOUT Truck loading and unloading racks should be designed to comply with ali lod, state, and federal regdations and to provide optimum ease in loading and unloading. Access mixis shauldbe

27、smooth and weli drained. Loading spots should be level and pderably hard surfaced to facilitate accurate filling and gauging. Tumaround areas should be provided to eliminate the necessity for backing the vehicles. (10,29,38) D. MARINE TERMINAL AND BARGE LAYOUT Movement of NGL by water should comply

28、with all local, state, and federal regulations and should be in accordance with API 2510 and the National Fire Protection Association (“A). (10,29,34) ENT AM INSTWTiON STANDARDS All equipment and installations involved in the loading of NGL should be designed, constructed, and operated in accordance

29、 with applicable codes and regulations. Although the NGL equipment and installations described herein are limited to current loading practices and regulations, nothing should be construed as limiting or restricting other methods, types of equipment, or installations which satisfy the basic safety pr

30、incipies implied herein. A. NGLBLENDING 5 GPA RB-194 94 = 3824699 OOLbbbb Ob9 B. Blending butanes and propane to certain percentages can be accomplished by pumping the required quantities of each product into a tank truck, tank car, or barge. The use of blending valves and/or static mixers is desira

31、ble. TRANSFER - LOADING AND UNLOADING 1. Piping Piping and valves for handling different products should be marked clearly for easy identification. 2. Pumps To minimize vapor lock in suction lines, loading pumps should be as close as practicable to the tanks from which suction will be taken. Loading

32、 pump:, must be designed to meet the highest loading pressure expected, but not to exceed the maximum working pressure of meiving tank. Pumping equipment should clearly be marked for identification. The installation of electricallydriven pumps should comply with Article 500 of the NEC. If a pump is

33、driven by an internal combustion engine, extreme care should be taken to ensure that any gas escaping from the pumps packing gland, or from any other source, does not reach a potential source of ignition. If it is necessary to install loading pumps below ground level or inside buildings, proper drai

34、nage and mechanical ventilation should be used to prevent the accumulation of flammable liquids or vapors. Gas detection alarms in the pump area may be advantageous.( 10,20,30) a. Positive Displacement Pumps Some type of device(s) should be provided on the discharge side of positive displacement pum

35、ps to relieve high pressure conditions and/or shut down the pump. b. Centrifugal Pumps Centrifugal pumps may be either the vertia or horizontal type. Generally, the vertical centrifugal pumps require less aboveground area for installation and lower tank elevation. Consideration should be given to th

36、e installation of safety devices for pump shutdown in the event of seal leakage or flow stoppage. Check valves should be installed on the discharge of centrifugal C. D. 3. pumps to prevent back flow. Some type of device(s) should be provided on the discharge side of centrifugal pumps to relieve high

37、 pressure conditions and/or shut down the pump.(6, 10,20,30) Compressors Compressors should be designed for use with NGL vapors. Compressors should take suction from the vapor space of the container being filled, and discharge to the vapor space of the container being emptied or elsewhere, A suction

38、 scrubber with a high liquid level shutdown device should be installed immediately upstream of the compressor to catch any liquids in the vapor line. (10,18,30) PIPE, VALVES, AND FITTINGS The piping installed in NGL loading and unloading facilities should be designed and constructed in accordance wi

39、th latest edition of ANSI B31.3, Chemical Plant and Petroleum Refinery Piping. Any piping that falls under the exclusion provided in 300.1 of B31.3 should be installed in accordance with ANSI B31.4. LOADING EQUIPMENT 1. Swivel Joints Swivel joints may be used with either piping or flexible hose to p

40、rovide moveable and retractable loading lines. Swivel joints should be of a type designed for NGL service and should be designed to withstand the maximum internal working pressure of the system, as well as any and all normal external loads to which they may be subjected. AU packing and lubricant mat

41、erials shall be suitable for NGL service. Hydraulic or mechanical counter- weights may be used to facilitate ease of handling. 2. Hose i1 All hose should be designed and fabricated for NGL service and shall meet all applicable rules and regulations. All hoses and connections shall be able to withsta

42、nd the maximum pressure for which the system was designed. Hoses should have a minimum bursting pressure of 1,750 psig and shall be marked “NGL“ or “LF“. The working pressure should 6 GPA RB-199 94 3824699 0036667 TT5 also be marked on the hose at not greater than 10-foot intervals. 3. Connections R

43、elief valves, excess flow vaives, check valves, and safety equipment should be in compliance with API Std. 2510, API Rp-520 Part 1, NFPA 58, and Bureau of Mines Buiietin #558. E. STENCHING EQUIPMENT A system should be provided to inject the proper amount of odorant (if required). The amount injected

44、 should be indicated on the delivery ticket. A means of verifying that the stenching equipment is functioning properIy should be provided. (18,30) F. ELECTRICAL Ail electrical work should conform to the NEC, and any applicable locai codes and regdationS. Area classifications should be in accordance

45、with applicable sections of API RP-500. In hazardous locations, only equipment approved for hazardous service should be used. G. FIREEXTINGUISHER Each tank truck should have at least one approved portable fire extinguisher with a minimum capacity of 20 Ibs. dry chemical and a B:C rating. (18,19,29)

46、H. FRE PROTECTION OF LOADING FACILITIES NGL fires can be extinguished with water/fog, dry powder, carbon dioxide, or steam. It is not ordinarily advisable to extinguish such ftres unless it is certain that the flow of NGL can be shut off immediately. Water/fog can be used to control a fm if extingui

47、shment is undesirable. Prompt and proper action in the fmt few minutes of any fire usually minimizes the magnitude of fue damage. It is desirable to have adequate, effective firefighting equipment available and conveniently located for immediate use. (10, 17,27,28,30,31,32) 1. PLACARDS In accordance

48、 with existing DOT regulations and local laws, it is the responsibility of the seiler to provide the carrier with the required identification numbers on placards for NGL, prior to the transportation in a cargo tank via motor carrier or tank car. The placards shall be on each end and each side of eac

49、h tank. (25.29) ER-GN CON- The general design of the loading and/or unloading facility should have safety as its first priority. A. IDENTIFICATION OF PRODUCT Identification is required to provide necessary information for seiier, transporter, custamer, regulatory bodies, etc. It may be accomplished by, but not limited to, the following 1. Data prwessing equipment 2. Printedcards 3. Preprinted ticket supplied by driver or customer 4. Written entry by driver 5. Key/cardentry. B. LOADINGEQUIPMENT 1. The loading installations should provide adequate flow and pressure controls to