Fisher Mills Inc. - Executive Summary |
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The current chlorine system is owned and maintained by Research Products as leased by Fisher Mills Inc. for use in the flour bleaching process. The system uses two one-ton chlorine cylinders on-line to dispense the chlorine into a vacuum system created by eductors feeding the flour agitators. Two additional one-ton cylinders are located within the same enclosure as either empty containers or full containers in standby valved off from the delivery system. The current system uses industry standard equipment, schedule 40 CPVC pipe well routed for safety, and is regularly inspected and maintained for integrity. The location of the current chlorine room is in the center of the flour mill complex, which is in an industrial area on the waterfront. Research Products regularly visits the flour mill to inspected the chlorine delivery systm, perform routine maintenance, make adjustments to the chlorine deilivery system, and other tasks as required to allow for efficient operation. Fisher M ills personnel receive the chlorine containers from the chemical supplier, transfer the containers into the chlorine room, and hook up the piping to the containers. Operators will shut off the chlorine delivery if necessary for flour production or if delivery problems occur. Resarch Products personnel are the only people making changes to the operating system with the exception of replenishing the feed stock as described. The controls on the current system involve a vacuum eductor on each of the six feed lines from the chlorine cabinet, that is remote from the chlorine room, and the flour agitators where chlorine contacts the processing flour and bleaching occurs. The vacuum activates a vacuum regulator in the chlorine room that is an industry-standard unit. A pressure sensor up stream from the vacuum regulator signals the operators that the supply is depleted. The chlorine cabinet has a block valve that fails closed in the event of power failure that would interrupt the air blo wer feeding the eductors. If the flour agitators plug, motion sensors will cause a power interruption to shut-down the blower and close the chlorine block valve. The worst case scenario is an un-controllable leak in a full chlorine container. With 110 lb/min leak rate, lasting 10 minutes, the radius of the affected area is 0.9 miles. The estimate for residential population within this area is 3,300 people. There are no schools or other institutions. The plant borders on a navigable waterway and there is a freeway approximately 0.25 miles away. The alternate case scenario envisions a pipe leak at 12 lb/min lasting 60 minutes. The affected area with 3.0 m/sec wind is less than 0.1 miles, about 500 feet, containing the affected area within the plant boundary in three of four cardinal directions. No residences, institutions, or freeways are involved, but the navigable waterway might be impacted depending on the wind direction. Over the last five years, there have been no reported incidents for the current chlorine dispensing system either at the Fisher Mills or in any other flour industry locations. The incident history within the chlorine supply industry is similarly without incident. The only known releases involve small amounts resident in the transfer lines during the container change process. Fisher Mills Inc. recognized the safety deficiences of the current system and has had a consulting engineering firm design a new system and facility to improve the material transfer and safety provisions. The new facility will have a single transfer operation from the supply truck to a container cart that will position the containers for hook-up to the piping system. The piping system system uses the most reliable hoses, valves, and piping material available to enhance the system safety. The new chlorine room will have improved ventilation in a two-stage ventilation system, a chlorine detection syste, emergency lighting, and emergency shut-offs. Central to the shut-off system is an independent valve shut-off system designed for one-ton chlorine cylinder yokes; this system is tied to the detection system, the power system, and has multiple manual emergency buttons. The detection system within the chlorine room will trigger the 10x airflow ventilation system at the first level (0.5 ppm Cl2) with full shut-down and alarm at the second stage (1.0 ppm Cl2). The scond stage will cause area-wide alams to alert personnel. At the dispensing area, additional Cl2 detectors will alert personnel to a 1.0 ppm Cl2 incident and activate transfer shut-down. Shut down at this location will cause a vacuum regulator shut-off with the chlorine room. The current controls will remain in the system. With the revised system im place, Fisher Mills will conduct training of all affected operating personnel in the areas of material transfer, background on chlorine, emergency procedures involved with the chlorine delivery system, and community emergency response a s needed. Enhanced relations with the Seattle Fire Department, the local hazmat response agency within the city, is another item that will evolve following the construction and start-up of the revised chlorine system. |