Electrical explosion proof and ventilation requirements for gas boiler rooms

1 gas boiler room explosion-proof design

Oil, gas boiler room boiler room gas regulator room, fuel pump room, pulverized coal preparation room, coal crusher room and coal transport corridor with explosion hazardous areas such as the classification, should be consistent with the current Chinese and European Union standards, “Explosion Hazardous Environment Electrical Installation Design Code” GB50058 of the relevant provisions; gas boiler room boiler room gas regulator room belongs to the explosion hazardous areas.

“Gas boiler room safety exit emergency evacuation indicator” close to the explosion hazardous area above or above the explosion shall be designed for explosion-proof type.

Meet one of the following conditions, can be categorized as non-explosion hazardous areas: 1, there is no source of release and there is no likelihood of infiltration of combustible substances into the area.

2. The maximum concentration of combustible substances that may occur does not exceed 10 per cent of the lower explosive limit value.

3, in the production process using open flames near the equipment, or hot parts of the surface temperature exceeds the ignition temperature of combustible substances in the area near the equipment;.

4. Outside the area of the production plant, in the open air or openly set up to transport combustible substances in the overhead pipeline zone, but its valve is determined on a case-by-case basis.

Based on 3 items: gas boiler room can be divided into non-explosion hazardous area.

Gas leakage is possible, when the concentration exceeds 10% of the lower limit of the explosive limit, the area near the roof of the boiler room is a natural gas storage area, lighting fixtures and switches to use explosion-proof type.

Combustible gas leakage concentration exceeds 25% of the lower limit of the explosive limit, the gas leakage alarm issued by the audible and visual alarm signals and start the accident exhaust fan, when the leakage concentration reaches 50% of the lower limit of the explosive limit, but also immediately shut down the natural gas source into the gas intake mains of the total intake solenoid valve, the boiler room near the roof of the lighting fixtures and switches, the accident exhaust fan selection of explosion-proof type.

Gas boiler room in addition to the gas regulator belongs to the explosion-hazardous area and the “explosion regulations” for the electrical explosion-proof design, gas boiler room and its adjacent control room and other ancillary rooms and other electrical design should be in accordance with the non-explosive hazardous area environment design.

2 gas boiler room gas safety measures

Introduced into the boiler room of the outdoor gas pipeline, in a safe and easy to operate location should be installed with the boiler room gas concentration alarm device linked to the emergency shut-off valve, the valve should be installed after the gas pressure gauge.

The gas pipeline shall be equipped with a discharge pipe, sampling port and blowdown port, and shall comply with the following provisions.

1, its location should be able to pipe and accessories within the gas or air blowing;.

2, the dispersion pipe can be combined into a master lead to the outdoors, the outlet should be higher than the ridge of the boiler room more than 2m, and should be released so that the gas does not run into the neighboring buildings and ventilation devices are sucked in.

3, the density of gas dispersion than air, should be used in the air or torch emissions, and should meet the minimum frequency of upwind side of the region’s safety and environmental protection requirements; when the plant has a torch venting system, it is appropriate to discharge the gas into the system.

13.3.5 The pipe diameter of the gas discharge pipe should be determined according to the volume of the blowing section and the blowing time; the blowing volume can be calculated according to the blowing section of 10 times ~ 20 times the volume of the blowing time can be used for 15min ~ 20min; the blowing gas can be nitrogen or other inert gases.

13.3.6 Boiler room gas piping should not cross the flammable or explosive warehouses, duty rooms, distribution and substation rooms, cable ducts (wells), elevator shafts, ventilation trenches, ducts, flues and corrosive properties of the site.

13.3.7 Each boiler gas trunk should be supported by reliable performance of the gas valve group, the valve group before the gas supply pressure and valve group specifications should meet the burner’s maximum load requirements; valve group basic composition and sequence should be cut off valve, pressure gauge, filter, pressure regulator valve, corrugated receiver, 2-level or combination of solenoid valves for leak detection, before and after the valve pressure switches and flow control butterfly valves; ignition of the gas pipeline should be used from the burner before gas Trunk pipe from the burner before the gas 2 or combined leak detection solenoid valve before the lead, and should be equipped with a shut-off valve and 2 solenoid valve on its level.

13.3.8 boiler gas valve shut-off valve before the gas supply pressure should be determined in accordance with the requirements of the burner, and should be set at 5kPa ~ 20kPa between the quality of the gas valve supply flow should be able to make the boiler in the rated load operation, the burner combustion stability.

13.3.11 gas pipeline vertically through the building floor, should be set up in an independent pipe wells, and should be laid against the outside wall; through the building floor pipe wells, every 2 or 3 layers should be set up not less than the floor fire-resistant limit of the fire partition; adjacent to the lower part of the two fire partitions should be set up Class C fire service door; the lower part of the building fire service door on the ground floor of the pipeline wells should be set up with an electrically operated fire damper Air intake louver; pipe wells should be set up at the top of the atmospheric louver; pipe wells should be used natural ventilation.

13.3.12 gas risers in the pipe wells should not be set on the valve.

13.3.13 gas piping and accessories are strictly prohibited the use of cast iron parts; in the fire zone to use the valve, should have fire-resistant properties.

3 accident ventilation system

Located in other buildings in the oil, gas boiler room boiler room, should be set up independent air supply and exhaust system, the ventilation device should be explosion-proof, ventilation must comply with the following provisions.

1, the use of gas as fuel, the normal ventilation should not be less than 6 times per hour, the number of accidents should not be less than 12 times per hour.

2, the boiler room is set up in the semi-basement or semi-basement, its normal ventilation should not be less than 6 times per hour, the number of accidents should not be less than 12 times per hour.

3, the boiler room is set in the underground or basement, the number of air changes per hour should not be less than 12 times.

4, the total amount of fresh air sent into the boiler room must be greater than the boiler room every hour 3 times the amount of air change.

5. The amount of fresh air sent into the control room shall be calculated according to the maximum shift operator.

15.3.8 gas regulator room and other rooms with explosion risk, there should be no less than 6 times per hour air change; when natural ventilation can not meet the requirements, mechanical ventilation devices should be set up and should be set up no less than 12 times per hour air change of the accident ventilation device; ventilation device should be explosion-proof.

15.3.10 mechanical ventilation room suction outlet location should be set up in accordance with the following provisions.

1, when the relative density of gas or oil is less than or equal to 0.75, the location of the suction outlet should be set in the upper area, the suction outlet on the edge of the plane to the ceiling or the roof distance should not be greater than 0.1m.

2 when the relative density of gas or oil is greater than 0.75, suction outlet location should be set in the lower area, suction outlet under the edge of the distance to the floor should not be greater than 0.3m.

When the air flow of ventilation in the explosion-hazardous area can make the combustible material is quickly diluted to the lower limit value of the explosion of 25% or less, can be designated as well ventilated, and should be consistent with the following provisions.

1 the following places can be designated as well ventilated places.

1) open-air places.

2) open buildings, in the building walls, roof openings, their size and location to ensure that the ventilation inside the building is equivalent to the effect of open space.

3) Non-open buildings with permanent openings for natural ventilation.

4) For closed areas, provide at least 0.3m3 of air per square meter of floor area per minute or at least lh air change 6 times.

2 When mechanical ventilation is used, the effect of mechanical ventilation failure may be excluded in the following cases.

1)closed or semi-closed buildings are provided with a standby independent ventilation system; and

2) In the event of a failure of ventilation equipment, precautions to ensure that the release of combustible substances is prevented, such as automatic alarms or stopping the process, or precautions to disconnect the equipment, are provided.