Gas burner safety control requirements

China's natural gas and coal gas (raw materials for coal) resources are abundant and clean energy, so there are good socio-economic benefits. However, in the design of gas burner development, gas characteristics - flammable, explosive and toxic, the primary issue of safety control. The following is an introduction to the gas burner safety control requirements: according to the combustion characteristics of gas in the furnace, the content of its safety control requirements are mainly pre-blowing, automatic ignition, combustion state monitoring, protection against non-ignition, protection against flame failure, protection against flame failure, protection against high and low gas pressure limits, protection against insufficient air pressure, power failure protection, measures to prevent gas leakage accidents, etc.

1.Pre-blowing air

Burner in the ignition before, there must be a period of pre-blowing air, the furnace and flue gas in the residual blowing or dilution. Because the work of the burner furnace inevitably have residual gas, if not pre-blowing air and ignition, there is a risk of explosion. The residual gas must be blown clean or diluted to ensure that the gas concentration is not within the explosion limit.

2.Automatic ignition

Gas burners should use electric spark ignition, to facilitate the realization of automatic control. Available high-voltage ignition transformer to generate an arc ignition, the output energy required: voltage ≥ 3.5K V, current ≥ 15mA.

3.Combustion state monitoring

Combustion state must be monitored dynamically, once the flame detector detects the flame out signal, must be a very short time feedback to the burner, the burner then into the protection state, while cutting off the gas supply.

4.The protection of non-ignition

When the burner is ignited, gas is introduced and the gas catches fire and burns. Ignition action is required to occur before the gas into the first formation of the ignition temperature field, to facilitate the ignition and combustion. If the fire does not ignite, the flame detector does not sense the flame signal, the burner enters the protection state. The time from ignition to enter the protection state should be appropriate, neither too short nor too long, generally required in 2-3 seconds into the gas, the burner to the flame detector to detect the flame signal to judge, not on fire then enter the protection state, on fire to maintain combustion.

5.Flame out protection

Burner in the process of combustion, if the accidental flame out, the burner into the protection state. As the furnace chamber is hot. Gas is prone to deflagration, so it must enter the protection state in a very short time, cut off the gas supply.

6.Gas pressure high and low limit protection

 Stable combustion of gas burners have a certain range, only allow gas pressure fluctuations within a certain range. The purpose of limiting the gas high and low pressure is to ensure flame stability: no flame off, no flame out and no flame back, while limiting the output thermal power of the burner to ensure the safe and economic operation of the equipment. When the gas pressure exceeds this range, the burner should be locked to work.

7.Insufficient air pressure protection

 The gas burner is designed with high thermal intensity and its combustion method is forced by the blower. If the fan fails to cause air interruption or air shortage, immediately cut off the gas, otherwise, the chamber will be burst combustion or backfire to the fan. Therefore, while improving the quality of the fan, the gas control must be interlocked with the air pressure, when the air pressure is insufficient, the gas supply should be cut off immediately.

8.Power failure protection

Burner in the process of working suddenly power failure, must immediately cut off the natural gas supply to protect the safety of equipment. Gas control solenoid valve must be normally closed type, once the power failure, automatically shut off the gas supply.

9.Measures to prevent gas leakage accidents

Gas leakage includes two aspects, one refers to the gas leakage to the environment through the pipeline, and the other refers to the gas leakage to the furnace through the end of the solenoid valve spool. Environmental leakage may cause poisoning and explosion at the work site, which must be paid great attention to. Leakage inside the furnace may cause an explosion inside the furnace. Prevention of gas leakage measures are peripheral control, generally not included in the burner body control.