Van Compressor Station - Executive Summary |
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Risk Management Program Executive Summary National Fuel Gas Supply Corporation Van Compressor Station 1) Accidental Release Prevention and Emergency Response Policies: It is the policy of National Fuel Gas to provide and maintain safe and healthful working conditions and follow sound operating practices that will safeguard our employees, our customers, our community, and environment. We will strive to comply with legislative requirements and eliminate any foreseeable hazards which may result in losses, damage to property, personnel injury and illnesses, and the environment. The Accidental Release Prevention Policy at the facility is embedded in our overall approach to planning, design and constructi on intended to minimize hazards; and the training of all personnel in proper operation, maintenance and inspection procedures with emphasis on awareness and practices to minimize hazards and avoid accidents. The Emergency Response Policy is to identify potential hazards at the facility, and develop and implement a plan to respond to emergency events including, but not limited to fire, accidents or injury. The Emergency Response Plan includes identification of responders and their duties, and procedures for notification of responders including fire department, evacuation, shutdown, and communications. 2) Stationary Source: The purpose of the Van facility is to withdraw field gas from a nearby production well gathering system, remove hydrocarbon liquid and moisture from the gas, raise the pressure of the gas, and deliver it into a natural gas transmission piping system. The operation is carried out by two interrelated, but distinct, majo r processes. The process that is covered by this Risk Management Program (RMP) is an extraction process which strips the hydrocarbon liquid (liquid product) from the natural gas, and stores it in a 30,000 gallon tank until it is shipped bi-weekly, via tanker truck. The other major process compresses the natural gas in three stages, pumps it through the extraction process and then into the high pressure transmission system. The extraction system process utilizes in series two counterflow heat exchangers, a chiller, and a three phase separator to reduce the gas temperature and pressure and which induces the liquid product to drop out of the gas stream. The chiller system uses propane refrigerant in a closed loop which includes a compressor, a cooler (condenser), a receiver, the chiller (evaporator), and a suction drum. There is also a 300 gallon propane makeup tank which feeds refrigerant to the closed loop as needed. After forming in the three phase separator the liquid product is passed through the heat exchangers to cool the incoming gas, and then sent to a stabilizer vessel where ethane gas separates (ethane is piped to the natural gas compressor for use as a fuel) and moisture is removed. From the stabilizer the liquid product is piped to the 30,000 gallon storage tank There is also an ethylene glycol dehydration system which removes moisture from the gas stream and the liquid product stream in two loops. In the first loop, glycol is injected into the gas stream at both the first heat exchanger and the chiller, and it is later removed in the three phase separator. In the second loop, glycol passes through the stabilizer to remove water from the liquid product. Both loops send the glycol through a reboiler which heats the glycol to drive off water, and then through a cooler. 3) Regulated Substances: The liquid product is a flammable liquid, and consists of an a pproximate a mixture of: i) Ethane: ii) Propane: iii) Butane: iv) Hexane: v) Pentane: Since the analytical composition of this liquid product varies depending on the gas mixture extracted from the production field, analytical analysis was performed to determine a general composition for this liquid product. This product is stored at approximately 50 to 100 pounds per square inch pressure. 4) Worst Case Release Scenario: The worst case release scenario, as defined by the EPA, was developed based on a release the largest quantity of liquid that the storage tank could possibly hold, the evaporation of the total quantity, and explosion of the vapor cloud. The explosion is assumed to reach an end point distance based on a model of an explosion of TNT in a quantity that has 10 percent of the estimated energy available in the liquid product. This scenario is based on the relea se of 30,000 gallons of liquid product, total evaporation, and explodes with an effective radius of 0.4 miles. This scenario is estimated to affect a population of 20 and a Church. The modeling used for end point determination was based on the RMP Off-site Consequence Analysis Guidance (OSA) Document, Published Friday, May 24,1996. In review of the OSA Document, it was determined to use an atmospheric over-pressure of 1.0 pounds per square inch as the end-point for the release. This end-point was chosen as the threshold because of the potential for serious injury to people as a result of property damage caused by the explosion, glass from shattered windows or falling debris. 5) Alternative Release Scenario: This alternate scenario is a release of a quantity of the regulated substance from a vessel or process line failure which is more likely to occur than the worst-case scenario. This release is assumed to result in a vapor clou d containing the total quantity of the substance between the Upper and Lower flammability limits which explodes and impacts offsite receptors. The alternative scenario was based on the release of the actual maximum contents of the liquid product storage tank, 18,000 gallons or approximately 81,200 pounds of liquid product, total evaporation, and explosion of the vapor cloud with an effective radius of 0.30 miles. This scenario is estimated to affect a population of 20 and a Church. The actual maximum tank content limit of 18,000 gallons is based on facility practice of keeping the tank at 60 percent or less of full. The modeling used for end point determination was based on the RMP OSA Document. From the OSA Document, it was determined to use an atmospheric over-pressure of 1.0 pounds per square inch as the end-point for the release. This end-point was chosen as the threshold because of the potential for serious injury to people as a result of property damage caused by the explosion, glass from shattered windows or falling debris. 6) General and Chemical-Specific Accidental Release Prevention Program: All personnel are trained in proper operation procedures of all equipment. Training and testing are conducted on-the-job. Any individual who works in this process must have extensive mechanical abilities, and is thoroughly tested and evaluated in the processing operations as part of the accident release prevention program Valves and other equipment are maintained, tested and replaced in-kind if necessary. Maintenance is performed on all compressors and systems based on written manufacturers' or facility procedures. The operational systems have general monitoring, maintenance and inspection performed to ensure optimum performance. The system operating parameters and equipment are monitored on a daily basis. Detailed audio and visual insp ections for leaks or signs of failure are conducted monthly. At least once per year the system is inspected with portable gas detection instruments for leaks from valves, flanges, pressure relief devices, and process equipment. In any instance where liquid product backs up out-of the system it automatically shuts down the compressors, activates the alarm system, and notifies site personnel by the automatic dialing system.. All critical monitoring and valve components have backups. The primary monitoring system includes level, pressure and temperature sensors and switches. If these fail the system is protected by numerous pressure relief valves. In most cases there are redundant relief valves, e.g. there are four redundant relief valve on the 30,000 gallon storage tank. The liquid product storage tank which has a maximum capacity of 30,000 gallons is never filled to full capacity. The standard operational procedure for is to mai ntain the liquid product storage tank at less than sixty percent of its total capacity, approximately 18,000 gallons. The storage tank is inspected daily to determine the amount of material present. To maintain this sixty percent total volume two truckloads per week of the liquid product are shipped when the facility is in full operation. Each shipment consists of approximately 8,500 gallons of liquid product per trip from the facility. The transport company, Crossett Trucking, follows specific written operational procedures for transferring liquid product from the storage tank to the tanker truck. There are spring loaded shut-off valves in the transfer piping to prevent potential releases related to transfer accidents. There is also minimal motor vehicle exposure to the liquid product storage tank,. It is surrounded by concrete Jersey barriers and access to the facility is normally through locked gates. This traffic pattern and s low speed reduce the potential exposure from vehicular traffic. All personnel entering the facility first must check in with the site operations personnel to unlock the access gates. 7) Five Year Accident History: To date this facility has no release of liquid product or other related incidents which caused off-site injuries, public evacuations, or any instances where personnel, the public, or the environment have been placed in danger from this operation. 8) Emergency Response Program: As part of the Emergency Response Program the Emergency Response Plan for the facility documents and outlines personnel responsibilities and procedures. This Emergency Response Plan is intended to establish a controlled and orderly means of response and control of emergencies in order to avoid unnecessary panic, injury, or death. During emergencies, existing hazards can change quickly, therefore the Emergency Response Program is intended as a guideline for emergency response. The Emergency Response Plan includes notifying and coordinating with local emergency responders, shutting down the compression systems, maintaining communications and evacuating the site. The site contacts are: Mr. David Gavin Office: 814-589-7061 Plant: 814-677-8618 Home: 814-827-6734 Mobile: 814-671-7515 Mr. Stanley Thompson Office: 814-589-7161 Home: 814-827-1978 Mobile: 814-671-7618 National Fuel Gas Supply Corporation Office: 800-833-1843 This operation runs 24 hours a day unless there is equipment repair or shut-down within the facility. There are operators present every day. Personnel spend several hours a day checking over system conditions and operation. If there is an emerg ency, with or without personnel present the system automatically shuts down, alarms are sounded, and the automatic dial in system immediately contacts and summons personnel to the facility. 9) Planned Changes to Improve safety: At the present time all operations are being reviewed and up-dated, and no changes to the operation or equipment at this facility are planned. |