Land O'Lakes Kent - Executive Summary
1.0 SOURCE AND PROCESS DESCRIPTION |
The Land O'Lakes facility in Kent, Ohio (the Kent facility) is subject to the USEPA's Risk Management Program (RMP) for Accidental Chemical Release regulation (40 CFR 68) because it has a refrigeration system that contains more than the threshold quantity (10,000 pounds) of anhydrous ammonia (CAS Number 7664-41-7). The entire system contains approximately 18,600 pounds of ammonia in various physical states (gas, liquid, and saturated vapor). The largest vessel is the controlled pressure receiver that operates at 75 psig and can contain as much as 9,100 pounds of liquid ammonia, assuming a 90 percent fill volume. However, during typical operation, the vessel holds only 4,600 pounds. Most of the ammonia equipment is located indoors. The condensing towers and some piping are located outdoors.
1.2 Process Description
The ammonia refrigeration system at the Kent facility is a single-stage system that controls the temperature for the process
ing and packaging of spreads. Equipment and piping carry the necessary gas, liquid, and saturated vapor throughout the system.
The ammonia refrigeration system is protected by the existence of specific safety systems/hardware, including safety relief valves (SRVs), engine room ventilation, and system safety interlocks. SRVs protect the compressor discharge, condensers, pumper drums, accumulators, and pump-out system from the hazards associated with over-pressure. Safety interlocks include high pressure and high temperature alarms and cutouts for the compressors, as well as high level floats and sensors for the vessels.
2.0 POTENTIAL RELEASE SCENARIOS
As required by the RMP rule requirements, two specifically defined release scenarios (a worst-case release and an alternative-case release) were analyzed to determine the maximum distance to an endpoint where the ammonia concentration is 200 parts per million in air, or 0.02 percent. The release scenarios analyzed are based upon the
guidance contained in the USEPA's Model Risk Management Program and Plan for Ammonia Refrigeration (the "Model Plan"), dated May 1996.
2.1 Worst-case release
The worst-case release is defined by the catastrophic rupture and complete loss of the contents of the largest vessel and associated piping (approximately 9,100 pounds of ammonia) over a 10-minute period. Using the specified worst-case meteorology contained in the "Model Plan" and assuming the facility is located in a rural area, the distance to the endpoint for a worst-case release extends beyond the facility's property boundary.
Although the worst-case consequence analysis is required by the RMP, it should be considered a highly unlikely event. Design, construction, and operation of the controlled pressure receiver is such that catastrophic failure is extremely remote. The receiver was designed and constructed in strict accordance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (S
ection VIII), and was certified and stamped by the National Board of Pressure Vessel Inspectors (National Board).
The vessel is operated well below the design pressure (i.e., maximum allowable working pressure) and because of the safety factors built into the ASME Code, a fourfold pressure excursion would have to occur before catastrophic vessel failure. If this were to occur, the vessel is equipped with dual safety relief valves (SRVs) set to relieve internal pressure at 250 psig. A high pressure excursion would not occur as long as the SRVs continued to function. Actuation of the SRVs would result in an ammonia release similar to that described in Section 2.2 for the alternative release scenario. The SRVs are replaced every five years, in accordance with the International Institute of Ammonia Refrigeration (IIAR) guidance contained in IIAR Bulletin Number 109, Minimum Safety Criteria for a Safety Ammonia Refrigeration System, to ensure that they will function properly when requi
The worst-case release scenario is unlikely for the following additional reasons:
7 The facility has a preventive maintenance program in place to maintain the ongoing integrity of the vessels;
7 The facility has a training program designed to ensure that the system is operated by qualified personnel;
7 Main ammonia shut-offs have been labeled to allow personnel to stop the flow of ammonia quickly in an emergency.
2.2 Alternative-case release
The alternative scenario is defined by a release of ammonia that is more likely to occur than the worst-case scenario, and reaches an endpoint offsite.
The "Model Plan" scenario was used for this analysis, which assumes a release of ammonia through a <-inch effective diameter hole in a high side (i.e., 150 psig) pipe or vessel, releasing 91.5 pounds of ammonia per minute. Because the building can serve as a passive mitigator to this release, passive mitigation was used to reduce the release rate and the distance to the endpoint. Using
the specified meteorology contained in the "Model Plan", the distance to the endpoint for the "more likely" release scenario extends beyond the facility's property boundary.
The alternative release scenario is unlikely for the following reasons:
7 Industrial standards were followed for the manufacture and quality control of these lines;
7 The facility has a sprinkler system in most of the plant;
7 Ammonia sensors exist throughout the plant, including four in the main cooler, one in the small cooler, one in the freezer and four in the engine room where the bulk of the ammonia exists;
7 The facility has a preventive maintenance program in place to maintain the ongoing integrity of the system; and
7 The facility has a training program designed to ensure that the system is operated by qualified personnel.
3.0 PREVENTION PROGRAM
The facility has carefully considered the potential for accidental releases of ammonia, such as the occurrence of the worst-case and alternative-case release sce
narios described in Section 2.0. To help minimize the probability and severity of an ammonia release, a prevention program that satisfies the Occupational Safety and Health Administration (OSHA), Process Safety Management (PSM) of Highly Hazardous Chemicals (29 CFR 1910.119) has been implemented. The key components of the prevention program are summarized below:
7 The development of an employee participation program, which includes Kent facility employees from all areas within the plant.
7 The development, documentation, and operator availability of critical process safety information regarding the hazards of ammonia, the design basis of the system, and the equipment. This information is used to fully understand and safely operate the ammonia refrigeration system.
7 The performance of a formal process hazard analysis (PHA) on the ammonia refrigeration system using a "What-If" Protection Analysis. A team with expertise in engineering, operations, maintenance, and safety evaluated t
he existing refrigeration system in depth and developed recommendations to improve the safety and operability of the system. The PHA is updated and revalidated every five years.
7 Standard operating procedures (SOPs) are used to provide the basis for proper and safe operation of the ammonia refrigeration system. The SOPs include procedures for normal operations, startup, shutdown, emergency operations, and emergency shutdown. They also describe safe operating limits for temperature and pressure, the consequences of operating outside these safe operating limits, and a description of safety systems and how they operate.
7 Refrigeration system operators receive refresher training at least every three years. The training content is based on the process safety information and operating procedures.
7 Contractors that are hired to work on, or adjacent to, the refrigeration system are "pre-qualified" based on their knowledge of ammonia refrigeration, understanding of applicable codes and st
andards, and their demonstrated ability to work safely. In addition, these contractors are periodically evaluated to ensure that they continue to work safely.
7 A preventative maintenance program is in place at the Kent facility. This includes regular inspection of major powered equipment, including compressors, pumps and large fans, bearings, couplings, shaft seals, mountings, etc., for vibration or incipient mechanical failure, and regular inspection and calibration of liquid level sensors, temperature and pressure instruments, switches and shutdown devices that have safety implications.
7 Formal authorization systems (i.e., management of change procedure, pre-startup safety review) are in place to ensure that system changes or expansions are as safe as the original design and that an independent recheck confirms that the changes are consistent with the engineering design and in a condition to be safely operated prior to startup.
7 Events that might cause an accidental or unexpecte
d release of ammonia are subjected to a formal investigation. The objective of the investigation is to correct deficiencies in such a way as to prevent recurrence.
7 Prior to the performance of any hot work (i.e., spark or flame producing operations such as welding, cutting, brazing, grinding), management must approve the work by executing a written hot work authorization permit to verify that precautions to prevent fire have been implemented.
7 Planning with the local fire department to ensure a rapid response to potential incidents with the system or external events, such as floods or tornadoes.
7 Adherence to fire codes and preparation for fires, storms, or events which could impact the ammonia system.
7 Prevention program compliance audits are performed every three years to verify that the appropriate management systems are in place and are being properly implemented. Any deficiency found in an audit is corrected.
4.0 ACCIDENT HISTORY
The Kent facility has had one accidental rele
ase of anhydrous ammonia from the refrigeration system in the past 5 years. This release occurred in May of 1998 when ammonia piping was accidentally bumped by the mast of a forklift, resulting in a pipe rupture. The Kent Fire Department, Portage County LEPC and the Ohio EPA were contacted. The Kent Fire Department responded to the release and evacuated most plant personnel. This accidental release did result in a section of the town being evacuated.
5.0 EMERGENCY RESPONSE PROGRAM
The Kent facility has implemented a detailed written Emergency Response and Evacuation Plan. The Plan is intended to address all emergencies at the facility, in addition to incidents related to a release of ammonia.