The Research On Combustion Control Of Multi-gas Species Gas Boiler

Currently, In the iron and steel enterprises, With the increasing degree of automation,The boiler control system is also asked to get higher and higher precision. Gas boiler fuel-gas,mainly from the iron blast furnace gas and coke plant coke oven gas and natural gas. Today, the general design of efficient gas-fired boilers can achieve90%, but in actual operation, because of load, fuel quality, work environment, pressure, oxy-acetylene ratio and other factors, often resulting in incomplete combustion of gas or air excess to reduce the thermal efficiency, resulting in energy waste and environmental pollution, in such a context, it is necessary for its closed-loop to feedback control of combustion systems.Gas boiler heat losses include mainly three parts, namely:heat losses, incomplete combustion and exhaust gas heat loss heat loss. Affected by the combustion system which is incomplete combustion and exhaust heat loss. Evaluation of exhaust gas heat losses and incomplete combustion heat loss factor is mainly participate in the excess air coefficient. Heat loss incomplete combustion with excess air coefficient decreases, while the exhaust gas heat loss with the excess air ratio increases, it is easy to see that there is an excess air ratio makes the best of both worlds, and the minimum, even with the highest thermal efficiency of boilers, combustion control purposes is precisely this.To achieve this purpose, this paper focuses on the boiler combustion system optimization coefficient of excess air and air-fuel ratio and oxygen content of the relationship. As the boiler combustion system, large disturbances, we actually find the best take is that the relative excess air ratio, the more important is to find the optimum excess air ratio range. This paper presents a creatively progressive adaptive genetic algorithm based optimization algorithm to dynamically find the best boiler excess air ratio. This algorithm and the biggest difference is that the general algorithm, it can quickly find the best interval. In addition, the traditional double-cross PID based combustion control, increasing single-variable predictive control layer, according to air-fuel ratio and oxygen content of the relationship between the line by rolling the optimal air-fuel ratio optimization. We designed two algorithms aimed at boiler combustion control system, control system but also other similar reference.We use the PLC as a programming tool to achieve the above-mentioned method, and through software simulation method, combustion control was simulated in the program design for the future and other similar control system left room for expansion. We are also air-fuel ratio on gas-fired boiler control experiments to verify the model accuracy and reliability of forecasting methods.Actual operating results show that the boiler combustion control system to improve efficiency and reduce the exhaust oxygen content, ensure that the system of economic, stability and security of operation, to achieve the energy saving.