Plant fires

Having discussed the fundamental cliaracteristics of fires in general and the different types of fire, we now c. aniine more closely fire accidents that occur in process phuits. Specifically, we review plant fire classifications, sources, causes, damage potentials, and detection and protection systems. 

Tlie National Fire Protection Association recognizes four general classification of fires.  

Class C Fires. Class C fires involve electrical equipment. The extinguisliing agents reconunended are dry chemicals, carbon dioxide, compressed gas, and vaporizing liquid. 

Class D Fires. Tlie last classification is reserved for fires occurring in combustible metals such as magnesiuin, litliium, sodium, and aluminum. Class D fires require special extinguisliing methods and agents, such as tlie grapliite-based type. 

Industrial plants contain a great number of possible ignition sources. A study made by tlie Factory Mutual Engineering Corporation of almost 25,000 indusUial fires reported over a decade indicates tliat, for tlie majority of fires, tlie origins can be traced to tlie following general sources  

Explosions, Toxic Emissions, and Hazardous Spills 

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Water. Water mains should be connected to plant fire mains at two or more poiats, so that a sufficient water supply can be deHvered ia case of emergency. The plant loop and its branches should be adequately valved so that a break can be isolated without affecting a principal part of the system. If there is any question of maintaining adequate pressure, suitable booster pumps should be iastaHed. Any connection made to potable water for process water or cooling water must be made ia such a manner that there can be no backflow of possibly contaminated water check valves alone are not sufficient. The municipal supply should faH freely iato a tank from which the water is pumped for process purposes, or commercially available and approved backflow preventers should be used. 

Heat for soldering is usually obtained from torches. The high conductivity of copper makes it necessary to use large flames for the larger sizes, and for this reason the location in which the joint will be made must be carefully considered. Soldered joints are most widely used in sizes 2 in and smaller for which heat requirements are less burdensome. Soldered joints should not be used in areas where plant fires are hkely because exposure to fires resiilts in rapid and complete failure of the joints. Properly made, the joints are completely impervious. The code permits the use of soldered joints only for Category D fluid service and then only if the system is not subject to severe cychc condions. 

Silver-brazed joints are used when temperature or the combination of temperature and pressure is beyond the range of soldered joints. They are also more reliable in the event of plant fires and are more resistant to vibration. If they are used for fluids that are flammable, toxic, or damaging to human tissue, appropriate safeguarding is required by the code. There are OSHA regulations governing the use of silver brazing alloys containing cadmium and other toxic materials. 

Emergency response plan A written plan which addresses actions to take in case of plant fire, explosion or accidental chemical release. 

User s Guide for a Personal Computer-Based Nuclear Power Plant Fire Database, August 1986. 

Another engineer arrived after another five or ten minutes. He fetched the process supervisor and then entered the vessel. He also collapsed. The supervisor ealled the plant fire service. Before they arrived the third man recovered sufficiently to be able to climb out of the vessel. The second man was rescued and recovered, but the first man died. It is believed that an hour or two before the incident, somebody opened the nitrogen valve leading to the vessel and then closed it. 

Water supply - It is the most important of all extinguishing agents for most chemical plant fires. The water supply should be sufficient to fulfill the demand for automatic protection and hose streams for at least a four-hour period. Allowance should be made for explosion damage to the system and protection against freezing. 

Some of tlie preceding cliapters liave dealt witli tlie history and legislation of emergency and accidents tliis cliapter addresses specifically tlie fundamentals of plant fires, explosions, and certain otlier plant- and non-plant-related accidents. 

The metliods of fire protection and prevention are dealt witli elsewhere. However, to conclude tliis section we present a brief discussion on plant fire fighting methods and equipment. 

The key to safety in explosives manufacturing is to use isolated high-velocity nitric acid reactors that have only a veiy small hold up at any one time (that is, only a small amount of dangerous material is held up inside the reactor at any time). Units are widely spaced, so any accident involves only small amounts of explosive and does not propagate through the plant. Fire and electrical spark hazards are rigorously controlled, and manpower reduced to the absolute minimum through automation. 

Figure 10.13. Vanadia wall deposits in a power plant firing Orimulsion fuel catalyze the premature oxidation of SO2 in heat exchangers. Note that potassium enhances the undesired conversion while a selective poison diminishes the effect to some extent.

Chemical plants—Fires and fire prevention. 2. Explosions. 

The finely divided maleate, a by-product of phthalic anhydride manufacture, is subject to rapid aerial oxidation above 150°C, and has been involved in plant fires. 

Arulanantham and Lees (1981) have studied pressure vessel failures in process plants such as olefins plants. They define failure as a condition in which a crack, leak or other defect has developed in the equipment to the extent that repair or replacement is required, a definition which includes some of the potentially dangerous as well as all catastrophic failures. In olefins plants fired heaters have failure rates of about 0.4 failures/year, while process pressure vessels have 0.0025 failures/year and heat exchangers 0.0015 failures/year. It is noticed that fired heaters are much unsafer than process pressure vessels, which are a little unsafer than heat exchangers. 

Calument City, IL, USA, Chemical Plant, Fire Reactor unit fire. 

Ft. McMurray, AK, USA, Oil Sand Plant, Fire Lube oil fire at compressor. 

Priola, Italy, Petrochemical Plant, Fire/BLEVE... 

Pulua Merlimau, Singapore, Bulk Storage Plant, Fire... 

Haifa, Israel, Chemical Plant, Fire Short circuit suspected as cause 22,000,000 loss... 

Chemical plants—Fires and fire prevention. 2. Petroleum refineries—Fires and fire prevention. 3. Explosions. I. Title. TH9445.C47N65 1996... 

Quite often jetties are fitted with their own water pumps, taking suction into the sea or river. The jetty fire water grid is often connected to the main plant fire water system as a backup. Care should be taken to avoid seawater corrosion of the main site fire water system. 

A system for reporting fires and alerting the plant fire brigade and the municipal fire department should be provided. This system should be as simple as possible to minimize the potential for confusion in emergencies. The preferred design is a multiplex system that alarms in the control room or some other 24-hour constantly attended location and activates visual devices, such as strobes or beacons, and audible notification devices, such as a steam whistle, air horn, or tone generator. Complete systems are available from recognized vendors. 

Plant fire brigade reaches emergency location (plant dispatch log)... 

The local fire department and plant fire brigade extinguished the fire at 12 10. 

At the NDF Company in Georgetown, South Carolina, a major fire occurred in the catalyst preparation area on August 1, 2001. The fire originated at Ketde No. 3 at 11 10 A.M. An explosion of catalyst storage tank No. 2 followed at 11 20 A.M. Final extinguishment of the fire was accomplished by the local fire department and plant fire brigade at 12 10 P.M. One fatality and five personnel injuries resulted from this event. 

The plant fire brigade and the local volunteer fire department were notified by the supervisor of the catalyst preparation area by 11 12 A.M. On their arrival to the scene of the fire at 11 15 A.M., the plant fire brigade saw the lead outside operator down about 40 feet from the fire, in between the catalyst preparation area and reactor building No. 1. They also found a seriously burned unknown person about 120 feet from the fire, near the finishing building. (This person was eventually determined to be a service contractor who entered the premises at 10 30 A.M. to calibrate equipment in the instrument house for Reactor No. 1.)... 

The fire engulfed most of the catalyst preparation area. Also, the automatic deluge sprinkler coverage for this area had actuated, hut no water was available. The fire brigade tried to activate a fixed monitor, but again got no water flow. With the limited water supply from the plant fire engine available as a shield, the fire brigade members felt they could reach the lead outside operator. 

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