The main difference between a fuel gas boiler and a layer-fired coal-fired boiler is the difference in the combustion system, which is mainly reflected in different fuel characteristics and combustion modes. The gas hot water boiler has the remarkable features of environmental protection, energy saving, safety and fully automatic operation. It is very convenient to use. In addition, due to the economic operation and government policies, gas-fired hot water boilers are more and more popular. The fuel gas boiler combustion system has the following two characteristics: (1) If the combustion process is improperly controlled, a large amount of combustible mixture will be formed in the furnace. When the mixture deflagrates, it will cause the furnace to explode, causing major property damage and personnel. Casualties; 2) The combustion mode of the fuel gas boiler is space combustion, fast burning speed and fast load response.
2. Fuel gas boiler
The automatic control requirements apply to the combustion system of a fuel gas boiler. The gas-fired steam boiler adopts the combustion machine under-position mode, the two-pass structure, the fuel combustion is sufficient, the boiler runs stably and takes up less space, and the smoke pipe is inserted with the spoiler to slow the smoke exhausting speed, increase the heat exchange amount, and the boiler thermal efficiency is high and lower. User use cost The fuel gas boiler automatic control system has the following basic requirements:
(1) Reliable system configuration to prevent fuel gas boiler explosion accidents. In the design of the fuel gas boiler automatic control system, the reliability of the system must be prioritized, if necessary The protection system can be designed independently of the detection and control system. When selecting a microcomputer control system, measures such as necessary backup manual control and important parameter double indication should be adopted to improve the reliability of the control and protection system.
(2) Strict program control is applied to the start and stop of fuel and gas boilers, and the fuel system, gas supply system and flame monitoring system are strictly tested during the start and stop process.
Strict program control is applied to the start and stop of oil-fired boilers and gas-fired boilers, and the fuel system, air supply system and flame monitoring system are strictly debugged. Avoid failures during startup and shutdown.
(3) According to the specific circumstances, select the following alarm and interlock protection items related to the combustion system:
1) Boiler water level over-limit alarm and interlock protection.
2) Boiler pressure overpressure (hot water boiler outlet temperature over temperature) alarm and interlock protection.
3) Flameout interlock protection.
4) Low oil pressure interlock protection (oil boiler).
5) High oil temperature interlock protection (oil boiler).
6) Low oil temperature interlock protection (oil boiler).
7) Low air pressure interlock protection (gas boiler).
8) High voltage interlock protection (gas boiler).
9) Low wind pressure interlock protection.
10) The burner flange limits the opening-related lock. Combustible gas leak alarm.
12) Seismic interlock protection. The hot water boiler is equipped with a computerized boiling water boiler controller. All functions are stored on a smart chip, which realizes the intelligent, digital, automatic and humanized boiler. The boiler intelligently controls the water temperature and reaches the water temperature heating to stop automatically. The water temperature is displayed and the temperature of the furnace water is clear at a glance.
(4) In the operation of the oil-fired boiler, when the flame is abnormally extinguished, the automatic control system is required to quickly cut off the fuel supply and prevent the fuel from entering the furnace, thus requiring the automatic control system to have a sufficiently fast response speed. (5) Linkage load adjustment When the load of the oil and gas boiler changes, the response speed of the fuel regulation is faster than the response speed of the air supply system. When the load suddenly increases, the increase rate of the fuel is greater than the corresponding increase rate of the air volume, resulting in insufficient combustion and black smoke; when the load suddenly decreases, the fuel is reduced faster, resulting in excessive oxygen content in the exhaust. For small boilers with position control, the increase or decrease of combustion should match the increase or decrease of air volume, otherwise it will cause flameout. Therefore, when designing an automatic control system, simultaneous adjustment of combustion and air should be considered. (6) Explosion-proof instruments for gas boiler automatic control system, field instruments should be explosion-proof instruments.
