The automatic control system of the gas generator (http://www.cngrjx.com/) generally consists of the following parts, namely the furnace body, primary instrument, field instrument, microcomputer, manual automatic switching operation, actuator, etc. The primary instrument converts the system's temperature, pressure, flow, oxygen content, speed, etc. into voltage, current signals, etc., and inputs them into the PLC, and then sends them to the microcomputer in the form of communication; the manual automatically switches the operating part. In manual mode, the operator manually controls it, and uses the operator to control the motor and valve, etc. In automatic mode, the microcomputer sends a control signal through the execution part for automatic operation.
2.1 Automatic furnace bottom pressure and temperature adjustment system. The boiler combustion process has three tasks: coal supply control, air supply control, and furnace bottom pressure and temperature control. Maintaining the ratio of gas to water vapor to make the combustion process more economical and maintaining automatic regulation of furnace negative pressure is a complex issue. In the past, the opening of the air damper was manually adjusted, which not only required a large workload and high labor intensity, but was also difficult to achieve precise control and affected gas quality. Through microcomputer control, the electric actuator automatically tracks the temperature control, which not only achieves precise control of temperature and pressure, but also greatly saves labor costs and improves the quality of gas.
2.2 Water level adjustment unit. The drum water level is an important parameter that affects the safe operation of the boiler. If the water level is too high, it will destroy the normal operation of the steam-water separation device. In severe cases, it will cause an increase in water in the steam, increase scaling on the tube wall and affect the steam quality. If the water level is too low, it will destroy the water circulation and cause the water wall tube to rupture. In severe cases, it will cause the pot to dry out and damage the steam drum. Therefore, if its value is too high or too low, it may cause major accidents. Its adjusted quantity is the steam drum water level, and the regulating quantity is the feed water flow. By adjusting the feed water flow, the materials inside the steam drum can reach a dynamic balance, and the changes are within the allowable range. Because the boiler drum water level responds positively to changes in steam flow and feed water flow.
However, when the load (steam flow) increases sharply, the performance is "reverse response characteristics", which is the so-called "false water level". The reason for this is that when the load increases, the drum pressure decreases, causing the boiling point temperature of the water in the drum to drop. The boiling of the water suddenly intensifies, forming a large number of bubbles, which raises the water level. The drum water level control system is essentially a system that maintains the balance of water inlet and outlet of the boiler. It uses water level as a control indicator for water balance. It adjusts the amount of incoming water to achieve inlet and outlet balance, and maintains the drum water level near the drum midline where the steam-water separation interface is the largest to improve the boiler's evaporation efficiency and ensure production safety. Since the boiler water level system is a controlled object with self-balancing capability, there is a false water level phenomenon during operation. In practical applications, a PID control system with single impulse of water level, double weight of water level and steam volume, and three impulses of water level, steam volume, and water supply can be used according to the situation.
2.3 Monitoring and management system. The above control systems are generally controlled by PLC or other hardware systems, and the following functions must be completed in the host computer: First, to accurately detect the operating parameters of the system in real time; second, to comprehensively grasp the operating conditions of the entire system. To this end, the monitoring system will monitor and collect system-related process parameters, electrical parameters, and equipment operating status in real time. The system has a rich graphics library. Through configuration, the system's device graphics and related operating parameters can be displayed on the screen; in addition, parameters can also be displayed in the form of lists or groups.
Comprehensive analysis and timely issuance of control instructions: Based on the monitored boiler operation data and the set control strategy, the monitoring system issues control instructions to adjust the operation of system equipment to ensure efficient and reliable operation of the system.
