China's natural gas and coal to gas resources are rich and thick, and belong to clean power, Gu has superior social and economic benefits. The gas incinerator is in line with the national policy, the situation trend prospect is very good, and there is a way out. However, in the development plan of gas incinerator, the main questions of gas characteristics - Flammability, explosion and toxicity, and safety control are discussed. The following describes the safety control request of the gas incinerator: according to the burning characteristics of the gas in the furnace, the contents of the request for safety control should include pre blowing, active combustion, monitoring of the burning condition, guard of non ignition, guard of flameout, guard of rugged gas pressure, guard of insufficient atmosphere pressure, guard of power failure, guard of gas leakage and disorder, etc.
1. Before combustion of pre blow incinerator, it is necessary to have a period of time pre blow to remove or dilute the residual gas in furnace and flue. Because the gas left in the furnace of the incinerator is unavoidable, if it is burned without pre blowing, there is a danger of explosion. It is necessary to blow out the remaining gas to clean or dilute, and ensure that the gas concentration is not within the explosion limit. 15-60 seconds for general construction related to the layout of furnace and blowing capacity
2. The active combustion gas incinerator should accept the electric spark combustion, so as to complete the active control. The high-voltage combustion transformer can be used to generate arc combustion, and its output energy is required to be: voltage ≥ 3.5kv, current ≥ 15mA, and the normal combustion time is: 2-5s.
3. Monitoring of incineration condition: dynamic and static monitoring must be carried out for the incineration condition. Once the flame detector senses the flameout signal, it must react to the incinerator in a very short time, and the incinerator will enter the guard condition immediately, and cut off the gas supply at the same time. The flame detector shall be able to sense the flame signal normally, neither sensitive nor slow. Because of its sensitivity, if there is turbulence in the burning condition, it is easy to cause misoperation and slow, and the reaction flame light signal lags behind, which is not conducive to safe operation. The response time of normal request from flameout to flameout light from flame detector shall not exceed 0.2S.
4. When the guard incinerator without ignition is burning, the fuel gas is introduced, and the fuel gas is on fire. The burning action request is generated before the gas is introduced, which first causes the burning temperature field for the convenience of burning. If the ignition is not on, the flame detector can not detect the flame signal, and the incinerator enters the guard status. The time from burning to entering the guard should be proper, neither too short nor too long. If it is too short, it will cause consolidated flame; if it is too long, it will cause a large number of gas to enter the furnace when the ignition is not on. It is generally requested that the incinerator verify the flame light number sensed by the flame detector within 2-3 seconds after the gas is injected. If there is no fire, the incinerator will enter the guard status, and if there is a fire, the incinerator will keep burning.
5. In the process of incineration, if the flameout is not detected, the incinerator will come in for protection. Because the furnace is hot and the gas is easy to produce deflagration when it enters, it is necessary to enter the protection condition in a very short time and cut off the gas supply. From the generation of flameout to the entry of the incinerator into the guard condition, the response time request of this process does not exceed 1 second.
6. The rugged gas pressure limits the protection of the gas incinerator. There are certain limitations to consolidate the combustion, only allowing the gas pressure to fluctuate within the certain limitations. The goal of limiting the rugged pressure of gas is to ensure the solidity of the flame: no desquamation, no flameout and no tempering; at the same time, limiting the output heat power of the incinerator to ensure the safe and economic operation of the building. When the gas pressure exceeds this limitation, the incinerator should be locked. The incinerator plans to use the gas pressure switch to sense the pressure light and output the switch value light to master the response of the incinerator. 7. The atmosphere pressure is not enough to protect the planned heat intensity of the gas incinerator, and the combustion method adopts the forced blast type. If the fan is obstructed, resulting in atmosphere infix or insufficient atmosphere, cut off the gas on time, otherwise furnace deflagration or tempering to the fan will occur.
In order to improve the quality of the fan, the gas control must be interlocked with the atmosphere pressure. When the atmosphere pressure is insufficient, the gas supply shall be cut off on time. Generally, the gas pressure switch is used to sense the gas pressure light and output the switch value light to master the response of the gas solenoid valve. 8. When the power is cut off, the incinerator will be cut off abruptly in the course of the event. It is necessary to cut off the gas supply on time to protect the safety of the building. The gas master solenoid valve must be normally closed. Once the power is cut off, it will cut off the gas supply actively.
The closing response time of the solenoid valve is ≤ 5s.9. There are two aspects to prevent the loss of gas leakage. One is that the gas leaks from the pipeline to the situation, and the other is that the gas leaks from the valve core end of the solenoid valve to the furnace. Leakage of the situation may cause poisoning of the staff, explosion and disorder at the scene of the incident, which must be highly faced up to. Start to ensure the sealing of the pipeline, and check the leakage of the pipeline on schedule. If the leakage of the pipeline needs to be eliminated, it can be used continuously. Secondly, avoid the gas concentration that leads to poisoning and explosion, and request the site ventilation superiority: build permanent ventilation hole and forced ventilation assembly. In addition, request the site not to allow the fire and explosion-proof electrical components. Leakage in the furnace may cause explosion in the furnace.
There are three ways to deal with the problem of leakage in the furnace: first, enhance the pre blowing air shade and blowing volume, and blow or dilute the gas in the furnace;
Second, the gas pipeline accepts two solenoid valves in series to improve the safety of the system;
The third is to use pipeline leakage inspection and assembly to inspect the gas pipeline before combustion. If the gas leakage reaches a certain amount, the incinerator will be locked.
——Author：ebico