| In order to meet the requirement of the user needs to load, it is inevitable that adjusting the operation such as load and coal. However, power plant personnel is all according to the real-time dynamic parameters and past experience to regulate but no optimization mode and target during operation so as to affect the dynamic characteristics of the boiler evaporation zone, the bad working conditions will produce the safe trouble such as slagging, pipe explosion, which changes its economy and safety. It is very necessary to strengthen the management of boiler operation and to adjust the operation optimization.Based on the actual unit CG-220/9.81-M as the prototype, small load disturbance evaporation system model is established according to the actual working conditions, the model is based on the dynamic balance of energy and mass, fully considering disturbance on thermal inertia of evaporation zone and turbine, by using SIMULINK modular thought establish a complete evaporation zone-turbine side online computational simulation platform. The simulation platform can online predict water wall effective absorb heat, steam drum outlet steam, drum water level of steam flow, and the main steam flow under different working condition of the boiler unit in small load disturbance of evaporation zone and optimize operation adjustment or offline simulation analysis. On the basis of the specific conditions in dynamic simulation test.Firstly, in order to analyze small changes fundamental reason on steam flow and drum water level, the simulation results show that the thermal inertia of the effective metal and saturated water in the evaporation area is the main cause of affecting its thermal inertia. Under the condition of small load disturbance water wall effective heat directly determines the drum outlet steam flow, and influenced by feed temperature, steam drum pressure, thermal inertia and pressure variable speed. The drum water level change caused by pressure, quality, bubble.Secondly, it provides technical support that natural circulation boiler in regulating operation optimization and improving the boiler running safety, the simulation results show that the fuel quantity is increased by 10% in 40s that initial pressure variable speed should be controlled within 0.01MPa/s in the evaporation zone; Fuel quantity less 10% in 40s that initial pressure variable speed should be controlled within 0.01MPa/s in the evaporation area. Fuel quantity optimization adjusted that the initial pressure variable speed within 0.01MPa/s, the fuel quantity should be controlled within 5%; The initial pressure variable speed within 0.01MPa/s, the fuel quantity should be controlled within 5%. The opening of the turbine tone is increased by 1% in 20s that initial pressure variable speed should be controlled within the 0.005MPa/s in the evaporation zone; The opening of the turbine tone is decreased by 1% in 20s that initial pressure variable speed should be controlled within 0.005MPa/s in the evaporation area. The opening of the turbine tone make the optimal regulation that the initial pressure variable speed within 0.005MPa/s, the opening of the turbine tone should be controlled within 0.32%; Initial pressure variable speed within 0.005MPa/s, the opening of the turbine tone should be controlled within 0.32%. Feed water flow rate increases 10% in 20s that initial pressure variable speed should be controlled within the 0.008MPa/s in the evaporation zone, feed water flow rate decreases 10% in 20s that initial pressure variable speed should be controlled within 0.008MPa/s in the evaporation zone. Feed water disturbance quantity optimization adjusted that the initial pressure variable speed within 0.008MPa/s, its feed water flow change should be controlled within 5%. Initial pressure variable speed within 0.008MPa/s, its feed water flow change should be controlled within 5%. The results of natural circulation boiler simulation benefit to regulating operation optimization and provide technical support to enhance the operation safety of the boiler. |
