Optimization Study on the Adjustment of Back Pressure for the Operation of High Back Pressure Pumped Condensing Heating Units in Different Heating Periods
High back pressure heating has the advantages of improving the overall thermal economy of the unit and enhancing the heating capacity of the unit.In this paper,based on the Ebsilon simulation model of a 600 MW subcritical direct air-cooled high back pressure pumped condensing heating unit,the char-acteristics analysis and adjustment optimization study of the unit operating back pressure in different heat-ing periods were carried out in terms of safety operation boundary,economy,heating capacity,peaking capacity and thermoelectric coupling.The results show that when the ambient temperature is lower than 5 ℃,the recommended operating back pressure is 33 kPa,and the back pressure needs to be adjusted according to the water supply temperature from 5 to 11 ℃,and the recommended operating back pressure is 13 kPa when it is higher than 11 ℃;the minimum safe flow rate of the unit increases from 140.4 t/h to 336.5 t/h as the back pressure is raised;the exergy efficiency of the spent steam heating and distribu-tion system is significantly higher than that of the extracted steam heating and distribution system,with the maximum value of 86.7％;the unit will reduce the peaking capacity when the back pressure is raised under low heating demand,and the peaking capacity fluctuation caused by the change of back pressure under higher heating demand is small,with strong thermoelectric coupling and small change of decoupling degree.
high back pressureload distributionexergy efficiencycoal consumption ratepower pea-king
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