船舶火灾和爆炸事故往往是重大的人身伤亡和设备损坏事故。船舶电气火灾和爆炸事故在火灾和爆炸事故中占有很大的比例，仅就电气火灾而言，不论是发生频率还是所造成的经济损失，在火灾中所占的比例都有上升的趋势。配电线路、高低压开关电器、熔断器、插座、照明器具、电动机、电热器具等电气设备均可能引起火灾。电力电容器、电力变压器、电力电缆、多油断路器等电气装置除可能引起火灾外，本身还可能发生爆炸。电气火灾火势凶猛，如不及时扑灭，势必迅速蔓延。电气火灾和爆炸事故除可能造成人身伤亡和设备损坏外，还可能造成船舶停航的重大事故。因此电气的防火防爆是一项重要的课题,本论文就电气的防火防爆展开论述
2 accident reason analysis
Analysis of gas boiler room the cause of the accident, there are two possible: boiler ontology explosion, boiler room to explode gas explosion concentration and explosions.
Boiler blast furnace body, because be in, or flue gas mixture in explosive existence, when achieved by fire or explosion limit, boiler heat ignites causing accidents in itself. This point and the national norm of building fire system that conform to the relevant provisions. The actual current boiler product has considered safe production measures to avoid it. Qualified gas boiler itself has the explosion-proof process design, such as burner in abnormal situation automatic stop, self-control device also stop output fuel, Gas boiler combustion system higher automatization, including the gas pressure is high, low limit alarm protection, when the control logic where step does not meet the conditions set start corresponding interlock protection.
Avoid the boiler exploded possibility, but still ontology exist above another possibility, can avoid? How to avoid it?
Three measures
In fact in design, according to the boiler design code "and" automatic fire alarm system design code "GB50116-1998 etc standard, we have taken the following measures:
Natural gas pipelines valves, meter, may occur gas leak place, boiler room may produce gas storage product area [relative density 0.8, it is to be in commonly roof area in these areas], all equipped with combustible gas concentration measurement alarm device, according to combustible gas concentration situation give out sound and light alarm signal and start exhaust fan, when leakage accident concentrations reach explosion limit of the lower limit 50% [this value for reference only], but also immediately close natural air intake duct total intake solenoid valves.
In the boiler room and a natural gas pipeline in and out of the room, the incident, but also with the smoke exhaust fan combustible gas alarm interlocking (start).
Electrical, instrument by cable selection TongXin, not less than 1.5 mm2 minimum section.
Gas radiation tube tube top or the nearby, the lightning rod should be installed above the pipe jacking tip should be not less than 3m, and its scope of protection tube top above not less than 1-m.
Gas pipeline should be static grounding device that, when pipeline as metal materials, and lightning protection or electrical engineering protective grounding wire connected, the measured resistance R more than 4 Ω. In pipe joints, such as the bend, flange, valve and pipe with good place cannot metal contact, also with metal soft line will be both ends jumper.
In the boiler room and a natural gas pipeline in and out of the room door, window take pressure measures.
According to the explosion and fire dangerous environment electrical device design specification "the laws 2.2.2 bar, accord with one of the following conditions may, when the explosion danger area: devin in item 3, in the process of production use fire equipment near, A combination of these several measures can clearly, electrical equipment selection for the explosion.
At the same time according to the explosion and fire dangerous environment electrical device design specification "the laws 2.2.2 bar, accord with one of the following conditions may, when the explosion danger area devin: the first 2 items, and the highest possible flammable explosive chroma does not exceed 10% of the lower limit, Close air intake duct natural total intake solenoid valves, concentration exceed 10% of the lower limit explosion limit, boiler room near the roof area are gas storage product area, so lighting lamps and lanterns and switch choosing is explosion-proof type.
4 conclusion
In gas boiler room electrical design, lighting choose explosion-proof lamps, other part adopts the explosion-proof type.
references
[1] boiler design standard. GB50041-1992.
[2] explosion and fire dangerous environment electrical device design standard. GB50058-1992.
[3] the code for fire protection design of buildings. GB50016-2006.
[4] automatic fire alarm system design standard. GB50116-1998.
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