Water Mist Fire Suppression System protecting the electrically powered shredder and the ballistic separator at an MRF in Devon
MRF Case Study - Suppression System Specification How the System Works This MRF Facility is an extremely advanced, highly automated plant which processes mixed commercial waste. The insurer had requested that the electrically powered shredding system and the ballistic separator were protected with an automatic fire suppression system. Blazequel were chosen to supply the correct solution for this specialist application. Due to the speed that the material was moving through the facility, we used high sensitively infra-red fire detection equipment to constantly monitor the risk areas for signs of a fire. These devices can also spot burning embers or sparks caused by the processes so are not reliant on the fire reaching the flaming stage to detect a risk. On detection of a fire, the process (and other equipment downstream) of the detected risk are immediately stopped to prevent adding to the flammable materials in the risk area. At this point, the water mist system immediately starts extinguishing. The water mist extinguishing system is constantly wet pressurised. This means that the entire system (including delivery pipework) is always ready to activate at a moments notice. On detection of a fire, extinguishing begins within 0.3 milliseconds. The water reservoir runs from a tank connected to the mains water supply - this stores 500lt under pressure and 500lt in storage. As the pressure is pump driven the system never has to be re-charged, unlike conventional systems that use a single use cylinder bank.
Shredder Fire Suppression System On the shredder we installed two infra-red spark detectors directly above the outfeed conveyor from the shredding chamber. The process of shredding is almost certain to create sparks. However, it is only the sparks that actually achieve to ignite flammable materials in the area that are actually likely to cause any damage. For this reason, we installed the detectors just above the point where the waste emits from the shredding chamber - this way, the system watches for burning embers that have been ignited by the shredding process but greatly reduces the chance of false alarms. On detection of a fire, the conveyor and shredder (seen on the previous page) are immediately stopped and extinguishment begins instantaneously. Two extinguishing heads are installed beside the detectors, above the outfeed conveyor to spray directly onto the detected risk, while a further six heads are installed on the sides of the shredder hopper - these will deluge into the hopper and down into the shredding chamber to ensure that any embers still in the shredder are extinguished. See below the Spark Detection Detection and Automatic extinguishing devices installed on the outfeed conveyor, just at the point where the waste emits from the base of the shredder. Note the water tank and control system in the background, mounted against the wall.
Shredder Fire Suppression System The image below shows the rear view of the shredder. You can see the row of extinguishing heads mounted through the side of the hopper. On activation these would discharge directly into the hopper, the water mist preventing the spread of fire up through the shredder and flooding down into the shredding chamber to extinguish any burning embers that may remain. At the bottom of the picture you can also see the extinguishers and detectors mounted at the foot of the outfeed conveyor.
Why do MRF s and other Recycling Facilities Require Fire Suppression Systems As recycling increases so do the demands on the recycling plants such as faster processing, larger machinery and longer working hours. All of these factors result in a higher risk for recyclers by increasing the probability of fire or explosion (particularly dust explosions), as well as increasing the consequences of such an event. Now more than ever, effective fire and explosion prevention is required for the safe and reliable running of a modern recycling facility. Danger zones of recycling plants A Blazequel spark detection and extinguishment system monitors and protects the following areas at risk: Shredders Impact sparks from foreign bodies Friction from material being processed Smouldering material entering the shredder Mechanical failure of the shredder Possible flammable liquids or gasses in waste material Overloading or material build-ups Bulk storage areas Smouldering material Consequences of Fires and Explosions A fire or explosion can have serious consequences for your company: Injury and loss of human life Damage to machines, transport facilities and storage space Processing interruptions Loss of income Repair or Replacements costs owing to damaged machines Failure to complete recycling contracts Conveyors Smouldering material Friction between material and conveyor Mechanical failure of the conveyor Dust extraction systems Sparks being extracted from the process into the dust filter or cyclone Spark being generated from fan units Sieves and Sorting equipment Mechanical impact sparks Friction between material and machinery Overloading or material build-ups Diagram of a recycling process showing possible protection areas Spark Detection Heat Detection Flame Detection Extinguishing Device
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