Coke Oven Flue Temperature Control Based on Improved Implicit Generalized Predictive Control

The flue temperature of coke oven is an important factor that guarantees the coke yield, the coke quality and the energy consumption of coking production. The heating process of coke oven is an object with multi control variables, nonlinear and large lag. The traditional PID control algorithm cannot further improve the control performance of the coke oven system. An improved implicit generalized predictive control algorithm with better control performance is proposed in this paper. Through inputting control increment value constrained by soft coefficient matrix, the calculation of matrix inversion is avoided. Soft coefficient matrix can reduce the computation time and ensure the rapidity of the system. At the same time, the input weight control law with smoothing filter is used to suppress the overshoot of the system output. Simulation results show that the proposed control method in this paper has the good control performance with faster computation speed. The proposed control method solves the problem of time variation and disturbance of coke oven system. The control algorithm of the coke oven flue temperature in this paper is effective.

The Interaction Effect Study of Ash Deposition and Acid Condensation on Low-Temperature Heat Transfer Surface in Boiler Flue Gas

The ash deposition on low-temperature heat transfer surface is a key factor that deteriorates the heat transfer performance and leads to corrosion in the low pressure economizer. In the low temperature flue gas, ash deposition is closely related with acid condensation. The sulfuric acid vapor and water vapor contained in the flue gas will condense on heat transfer surface under low flue temperature, which will aggravate ash deposition. In order to evaluate the influence factors of ash deposition on low-temperature heat transfer surface, a laboratory experiment is carried out in this paper. The acid concentration of flue gas, the ash content, the ash component, the flue temperature and the temperature of heat transfer surface are considered to be the most important influence factors on ash deposition characteristics. The viscosity of ash deposition samples on the outer wall of the double-pipe is measured to describe ash deposition characteristics. The fouling factor is calculated. Meanwhile, the scanning electron microscope SEM is used to the analysis of ash samples obtained from the outer wall of the double-pipe. As conclusion, the changing regulation of viscosity of ash deposition on low-temperature heat transfer surface is obtained. (CSPE)

Influence of Gas-Gas Heater on Wet Flue Gas Desulfuration

Material balance calculation was adopted to a wet flue gas desulfurization (WFGD) system for exploring impacts of gas-gas heater (GGH). Effects of GGH on flue and water consumption were analyzed. Results showed that inlet flue temperature of desulfurization tower reduced by 3.4 °C at 100% load after installation of GGH. Exhausted gas temperature of system increased by 34.9°C. The heat release of original flue in desulfurization tower reduced by 43.72%. Plume rise height was significantly improved. Water evaporation in desulfurization tower declined by 42.07%.Amount of addendum water reduced by 39.06%, and water vapor carried by flue decreased by 19.78% at the outlet of WFGD. Therefore, operation condition of flue emission is improved and water consumption decreases with GGH.