【Daily Question 20090327】What are the basic schemes for the combustion control system?
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What are the basic schemes for combustion control systems?
Fixed-ratio dual closed-loop control loop: The flow ratio of fuel to air remains constant, with the set value for air being determined based on the fuel flow in a specific proportion. Variable ratio dual closed-loop control loop: The flow ratio of fuel to air is adjusted based on the temperature of the air, with the fuel flow being determined by the air flow according to the ratio corresponding to that temperature.
1: Control of fuel quantity: When the requirements of the load change, it is necessary to adjust the amount of fuel burned accordingly. 2: Control of air supply volume: To achieve efficient combustion, it is essential to adjust the air supply volume accordingly so that it matches the amount of fuel used. 3: Control of exhaust air volume: To keep the furnace pressure within the desired range
The fixed and variable ratios on the 2nd floor are used in ammonia synthesis; the purpose is to control the ratio between nitrogen and hydrogen, and generally, the nitrogen flow rate is adjusted to accommodate changes in the hydrogen amount, mainly for economic reasons. The controlled air supply volume on the 3rd floor should be more or less the same as this. Controlling the exhaust air volume involves regulating the flow rate of flue gas at the outlet of the heating furnace in order to control its pressure. There are two operating modes for the pressure of the heating furnace: one is positive pressure, meaning that the pressure inside the furnace is slightly higher than the external atmospheric pressure; the other is negative pressure, with the pressure being slightly lower than the external atmospheric pressure. Positive pressure is easier to control, while negative pressure is more difficult to manage, as it can lead to backflow of flue gas: lol.
Boiler combustion control: 1. Drum water level control; 2. Furnace negative pressure control; 3. Main steam pressure and flow control; 4. Air-coal ratio; 5. CBF boilers also have bed temperature control. . .