【 Weak current College 】 large flammable material on the design of the transport corridor fire

1 preface

Trestle refers to transporting material overhead bridge. Trestle bridge transport mainly uses the belt conveyor equipment or pipeline transportation equipment, from a closed form view into enclosed, half-closed and open type. In recent years, with the constant improvement of production capacity, production and demand for raw materials continued to expand, material conveying bridge began to large-scale development, some large trestle transmission distance has thousands of m, transport capacity is as high as several thousand tons per hour.
The architectural design of the fire code only on the trestle of building construction, fire separation of content provided that the other does not fire design. For large material conveyor trestle bridge, and in particular the combustible material conveyor trestle bridge, its fire design basic references with the hazard category of the plant. The author with several large, Rizhao, combustible material conveyor trestle (hereinafter referred to as the "bridge") examination on the trestle of opinions by the fire protection design, with peers, and designers to explore. This article discusses the combustible material conveying of large bridge means transmission distance in 1 km above, conveying capacity of 1 000 t/h of combustible material conveyor trestle bridge, on the other combustible material conveyor trestle bridge design is for informational purposes only.

2 fire risk analysis

2.1 conveying material for fire hazard
The transportation of flammable trestle bridge articles mainly has the coal, grains and their products, timber, oil and liquid chemical products, these items have a very high fire danger, of which oil, liquid chemical products are distributed by gas and cereals, flour, feed, flour and other items of dust also have explosion hazard, coal and grain also has a spontaneous combustion characteristics.
2.2 conveying equipment for fire hazard
Trestle of transportation equipment mainly conveyor belt and pipelines. Belt conveyor belt is driven by the motor in belt roller conveying material on campaigns. Belt rollers in a normal State should be free in a fixed axis rotation, but if the failure cannot be free rotation, will make the leather belt and belt roller friction between, if not timely detection, long friction heat will cause the belt and the transportation of goods burning fire. Oil and liquid chemical products are mainly used for transportation, pipelines in the long-term delivery process, if not get regular maintenance, the pipe may be easy to produce corrosion of parts of the leak, it is easy to result fire and explosion.

3 fire characteristics

3.1 beginning fire found difficult to fire spread speed
Typ, trestle only have small staff conduct regular inspection. For long-distance patrol a large bridge, once the time is very long, only rely on the defence, it would be difficult at the beginning of the fire was discovered in a timely manner. In the event of fire, will rapidly spread along the bridge.
3.2 fire suppression difficult
Trestle is apart from the ground is generally a certain height, the audit found that some enterprises which need due process trestle bridge section, or even dozens of meters away from the ground level, in the event of fire, will bring great extinguishing work more difficult.

4 fire design of trestle bridge

4.1 site of bridge
Trestle site should be as far away as possible from residential areas, public buildings and flammable and explosive articles production, storage, and other buildings outside the enterprise perimeter walls and internal factory, warehouse, shall maintain 13 m above the fire separation, and internal flammable, explosive articles production, storage area of the fire separation should be consistent with the relevant technical specification for the same amount of risk class factory.
4.2 trestle bridge building construction
Trestle bridge pillars, frames, load bearing members, such as the use of reinforced concrete structures. The use of steel structures, bridge internal exposed steel components should brush fire retardant coating, fire resistance should meet the architectural design fire protection standard fire-resistance rating in the secondary build, structure component fire resistance requirements. Trestle on any part of the combustible materials should not be adopted.
4.3 trestle of fireproofing
In order to prevent the landing stage to the rapid spread of the fire after fire, should be transferred in the bridge and the tower and the factory, warehouse connection of a door set fire to separate the water curtain. Water curtain of water spray intensity should be not less than 2 per meter L/s, the nozzle should be performed on the head or open sprinkler nozzles, should ensure the water curtain width not less than 6 m door, each separated by a curtain of fire use thermal shower valve control.
4.4 trestle of evacuation
In order to ensure the fire after landing stage internal work inspection personnel quickly and safely evacuate, trestle bridge should have emergency escape exit, exit below should be set up the bridge pillars on the ladder, trestle work within any dots in the nearest emergency exit evacuation distance should not be more than 80m.
4.5 trestle of fire
Combustible material conveyor trestle belt conveyor with belt should be handled with flame retardant materials for conveying a dust explosion hazardous materials of the trestle bridge, its belt with metal materials is strictly prohibited. Transport of dust or gas explosion hazardous materials of trestle use semi-enclosed structure or open structures. To use a sealed structure, mechanical ventilation must be set to strengthen internal ventilation of the trestle bridge. Oil and liquid chemical products transported within the trestle bridge to pipeline valve, the sampling population and the vicinity of flammable gas detection alarm or configure a certain number of laptop alarm.
4.6 trestle fire facilities
Trestle on the inside of the building design fire protection standard and the construction of fire extinguishers configuration design code of the relevant requirements set indoor hydrant and mobile fire extinguishers, outdoor fire water should make full use of the nearby natural water and municipal water supply.
As a preliminary trestle fire has found difficult, since the fire spread rapidly, and other characteristics,Recommendations within the trestle set automatic fire alarm systems and automatic sprinkler systems, will help to quickly and efficiently discover, fire extinguishing and suppressing the beginning fire spread, to avoid greater losses. Automatic fire alarm system setting is in line with national standards of the automatic fire alarm system design code of the relevant provisions for belt conveyor, detectors should be cable-style fixed temperature detector, and should be set in a conveyor roller and belt contact point and so prone to overheating and friction parts close by. System alerts, System linkage control equipment should be immediately cut-off belt power. The sprinkler system shall conform to the standards set the automatic sprinkler system design code of the relevant provisions of the system should be closed sprinkler system, for without insulation measures should be adopted for the trestle bridge, dry-type system and the system should follow in the design of risk level 2. For belt conveyor equipment, the system should be set above the belt, the nozzle should be below the belt roller belt in the vicinity of cooling nozzle.

5 the proposal

Large flammable material conveying bridge as a special kind of building, structure, its design has become a new topic. Through practice and borrow check similar foreign practice of large-scale goods trestle, has accumulated much experience, the proposed national fire technical specifications are revised, the conveying of combustible materials for large bridge fire design detailed provisions.