As valuable energy in iron-and steel-making process,by-product gas is widely used in heating and technical processes in steel plant.After being used according to the technical requirements,the surplus by-product gas i...As valuable energy in iron-and steel-making process,by-product gas is widely used in heating and technical processes in steel plant.After being used according to the technical requirements,the surplus by-product gas is usually used for buffer boilers to produce steam.With the rapid development of energy conservation technology and energy consumption level,surplus gas in steel plant continues to get larger.Therefore,it is significant to organize surplus gas among buffer boilers.A dynamic programming model of that issue was established in this work,considering the ramp rate constraint of boilers and the influences of setting gasholders.Then a case study was done.It is shown that dynamic programming dispatch gets more steam generation and less specific gas consumption compared with current proportionate dispatch depending on nominal capacities of boilers.The ignored boiler ramp rate constraint was considered and its contribution to the result validity was pointed out.Finally,the significance of setting gasholders was studied.展开更多
Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full scale furnace fired tangentially at four corners is adopted. “ k ε ” turbulence...Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full scale furnace fired tangentially at four corners is adopted. “ k ε ” turbulence model is used for the gas phases and a stochastic approach based on the Lagrangian technique is used for particle phases. Two competing reactions model for the coal devolatilization and PDF (the probability density function) method for the combustion of the gas phases are employed. In the numerical simulations, assuming the air distribution of second port level is of pagoda, waist drum and uniform type. The results show that pagoda type air distribution is advantageous to ignition and smooth combustion of pulverized coal, and suitable to inferior coal combustion in practice. In the present furnace, the igniting distance at 1st and 3rd corner is longer than that at 2nd and 4th corner. The results from numerical calculations are in good agreement with those of observed in practice.展开更多
Considering the fact that the temperature distribution in furnace of a tangential fired pulverized coal boiler is difficult to be measured and monitored, two-stage numerical simulation method was put forward. First, m...Considering the fact that the temperature distribution in furnace of a tangential fired pulverized coal boiler is difficult to be measured and monitored, two-stage numerical simulation method was put forward. First, multi-field coupling simulation in typical work conditions was carried out off-line with the software CFX-4.3, and then the expression of temperature profile varying with operating parameter was obtained. According to real-time operating parameters, the temperature at arbitrary point of the furnace can be calculated by using this expression. Thus the temperature profile can be shown on-line and monitoring for combustion state in the furnace is realized. The simul-(ation) model was checked by the parameters measured in an operating boiler, (DG130-9.8/540.) The maximum of relative error is less than 12% and the absolute error is less than 120℃, which shows that the proposed two-stage simulation method is reliable and able to satisfy the requirement of industrial application.展开更多
In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and ...In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and then increase the unit output.However,restricted by the low temperature of waste flue gas,the energy-saving efect is inconspicuous.Based on the common waste heat utilization system of the flue gas.展开更多
When large-scale circulating fluidized bed(CFB)boilers are working under a 1ow load condition.severe bed pressure swing often occurs and poses a serious threat to boiler stability and safety.Up to now,there are not en...When large-scale circulating fluidized bed(CFB)boilers are working under a 1ow load condition.severe bed pressure swing often occurs and poses a serious threat to boiler stability and safety.Up to now,there are not enough theoretical studies on the bed pressure swing phenomenon.展开更多
A simple two-by-two model for a boiler-turbine unit is derived in this paper, which can capture the essential dynamics of the typical process. The coordinated controller is designed based on this model. A PID control ...A simple two-by-two model for a boiler-turbine unit is derived in this paper, which can capture the essential dynamics of the typical process. The coordinated controller is designed based on this model. A PID control structure and a tuning procedure are proposed. The example shows that the method is easy to use and can achieve an acceptable performance.展开更多
基金Project(L2012082)supported by the Science and Technology Research Funds of Liaoning Provincial Education Department,China
文摘As valuable energy in iron-and steel-making process,by-product gas is widely used in heating and technical processes in steel plant.After being used according to the technical requirements,the surplus by-product gas is usually used for buffer boilers to produce steam.With the rapid development of energy conservation technology and energy consumption level,surplus gas in steel plant continues to get larger.Therefore,it is significant to organize surplus gas among buffer boilers.A dynamic programming model of that issue was established in this work,considering the ramp rate constraint of boilers and the influences of setting gasholders.Then a case study was done.It is shown that dynamic programming dispatch gets more steam generation and less specific gas consumption compared with current proportionate dispatch depending on nominal capacities of boilers.The ignored boiler ramp rate constraint was considered and its contribution to the result validity was pointed out.Finally,the significance of setting gasholders was studied.
文摘Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full scale furnace fired tangentially at four corners is adopted. “ k ε ” turbulence model is used for the gas phases and a stochastic approach based on the Lagrangian technique is used for particle phases. Two competing reactions model for the coal devolatilization and PDF (the probability density function) method for the combustion of the gas phases are employed. In the numerical simulations, assuming the air distribution of second port level is of pagoda, waist drum and uniform type. The results show that pagoda type air distribution is advantageous to ignition and smooth combustion of pulverized coal, and suitable to inferior coal combustion in practice. In the present furnace, the igniting distance at 1st and 3rd corner is longer than that at 2nd and 4th corner. The results from numerical calculations are in good agreement with those of observed in practice.
文摘Considering the fact that the temperature distribution in furnace of a tangential fired pulverized coal boiler is difficult to be measured and monitored, two-stage numerical simulation method was put forward. First, multi-field coupling simulation in typical work conditions was carried out off-line with the software CFX-4.3, and then the expression of temperature profile varying with operating parameter was obtained. According to real-time operating parameters, the temperature at arbitrary point of the furnace can be calculated by using this expression. Thus the temperature profile can be shown on-line and monitoring for combustion state in the furnace is realized. The simul-(ation) model was checked by the parameters measured in an operating boiler, (DG130-9.8/540.) The maximum of relative error is less than 12% and the absolute error is less than 120℃, which shows that the proposed two-stage simulation method is reliable and able to satisfy the requirement of industrial application.
文摘In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and then increase the unit output.However,restricted by the low temperature of waste flue gas,the energy-saving efect is inconspicuous.Based on the common waste heat utilization system of the flue gas.
文摘When large-scale circulating fluidized bed(CFB)boilers are working under a 1ow load condition.severe bed pressure swing often occurs and poses a serious threat to boiler stability and safety.Up to now,there are not enough theoretical studies on the bed pressure swing phenomenon.
基金Supported by Specialized Research Fund for the Doctoral Program of Higher Education (20020079007)
文摘A simple two-by-two model for a boiler-turbine unit is derived in this paper, which can capture the essential dynamics of the typical process. The coordinated controller is designed based on this model. A PID control structure and a tuning procedure are proposed. The example shows that the method is easy to use and can achieve an acceptable performance.
