Safety control requirements for natural gas burners: According to the combustion characteristics of the gas in the furnace, safety control requirements mainly include pre-blowing, automatic ignition, combustion status monitoring, misfire protection, flameout protection, high and low pressure limit protection, etc., and insufficient pressure protection. , power outage protection, measures to prevent gas leakage accidents, etc.
1. Pre-blown natural gas burnerπ₯
Before the burner is put into operation, there must be a period of pre-blow to blow off or dilute the residual gas in the combustion chamber and flue. Since residual gas inevitably exists in the working room of a natural gas burner, there is a risk of explosion if it is ignited without pre-blowing. The remaining gas must be blown off or diluted to ensure that the gas concentration is not within the explosion limit.
The pre-blowing time is related to the furnace structure and air blowing volume, and is generally set to 15-60 seconds.
2.Automatic ignitionπ₯
Natural gas burners should use electric spark ignition to facilitate automatic control. The high-voltage ignition transformer can be used to generate arc ignition. Its output energy requirements are: voltage β₯ 3.5kV, current β₯ 15mA, and ignition time is generally 2 to 5 seconds.
3. Combustion status monitoringπ₯
Combustion status must be dynamically monitored. Once the flame detector detects the flameout signal, it must feed back to the natural gas burner within a short time, and then enter the protection state and cut off the gas supply.
The flame detector must be able to properly sense the flame signal and be neither sensitive nor inactive. Due to its sensitivity, if the combustion state fluctuates, it can easily cause malfunctions and slowdowns. The feedback flame signal is delayed, which is not conducive to safe operation. Under normal circumstances, the response time from flameout to the flame detector sending out a flameout signal is no more than 0.2 seconds.
4. Fire prevention measuresπ₯
When the natural gas burner is ignited, gas is introduced, which ignites and burns. The ignition action requires the formation of an ignition temperature field before the introduction of gas to facilitate ignition and combustion. If ignition fails, the flame detector cannot sense the flame signal and the burner enters the protection state.
The time from fire to protection should be appropriate, neither too short nor too long. If it is too short, there will be no time to form a stable flame; if it is too short, there will be no time to form a stable flame. If the time is too long, a large amount of gas will enter the furnace when it cannot be ignited. The burner is usually required to determine the flame signal detected by the flame detector within 2-3 seconds after gas supply. If it does not catch fire, it will enter a protected state, if it catches fire, it will continue to burn.
5. Flameout protection measuresπ₯
During the combustion process of the burner, if it is accidentally extinguished, the burner will enter the protection state. Because the stove is very hot. Gas can easily ignite, so it is necessary to enter a protective state and cut off the gas supply within a very short time. The response time of this process from flameout to the burner entering the protection state should not exceed 1 second.