集中供热系统水力热力耦合特性辨识方法研究

Identification Method for Hydraulic and Thermodynamic Coupling Characteristics of a Central Heating System

集中供热系统的运行能效主要受其水力热力特性的影响,换热站作为连接热源、热网和热用户的枢纽,是分析系统水力热力特性的关键,站内设备的长期运行性能衰减会导致供热系统整体能耗升高、能效下降,因此有必要对站内设备的运行性能进行诊断.基于换热站实测运行数据,分别采用最小二乘法和梯度下降对站内主要设备包括换热器、循环泵和调节阀的性能曲线进行了辨识,从而构建了集中供热系统的水力热力特性计算方法,全面分析了某典型换热站主要设备性能衰减情况和能耗水平,对主要设备运行性能进行了评估,并对设备维护的经济性和碳减排效果进行了计算.结果表明:换热站内主要设备性能存在不同程度衰减,其中换热器传热系数由1.00 kW/(m^(2)·K)下降至0.64 kW/(m^(2)·K),循环泵标况扬程由22.4 m下降至17.3 m,调节阀流通能力由183.0 t/h下降至82.4 t/h,且阀门整体开度较低,以上问题导致了系统整体能耗的增加;为消除气候变化对集中供热系统能耗分析的影响,结合度日数和实际供热面积,对系统能耗进行评价,与标准年相比,测试年采暖季同期平均热耗和电耗分别增加了0.86 GJ/(104 m^(2)·℃·d)和2.38 kW·h/(104 m^(2)·℃·d);对主要设备进行清洗和更换后,集中供热系统采暖季诊断时间内的同期累计电耗可降低16.3%,全生命周期内CO_(2)排放量可减少128.5 t.

The operational energy efficiency of a central heating system is mainly affected by its hydraulic and thermodynamic characteristics.As the hub connecting the heat source,network,and user,the heat exchange station is crucial for analyzing the hydraulic and thermodynamic characteristics of the system.Attenuation of the long-term operational performance of the main equipment in the station will lead to an increase in the overall energy consumption and a decrease in the energy efficiency of the heating system.Therefore,diagnosing the operational performance of the equipment in the station is necessary.Based on the measured operation data of the heat exchange station,the performance curves of the main equipment,including heat exchangers,circulating pumps,and regulating valves,were identified using the least square method and gradient descent to develop a calculation method for measuring the hydraulic and thermodynamic characteristics of the central heating system.The performance attenuation and energy consumption level of the main equipment in a typical heat exchange station were comprehensively analyzed.Furthermore,its operational performance was evaluated,and the economic and carbon emission reduction effects were calculated for equipment maintenance.The results show that the main equipment in the heat exchange station exhibits different degrees of attenuation.Specifically,the heat transfer coefficient of the heat exchanger decreases from 1.00 kW/(m^(2)·K)to 0.64 kW/(m^(2)·K),the standard condition head of the circulating pump decreases from 22.4 m to 17.3 m,and the flow capacity of the regulating valve decreases from 183.0 t/h to 82.4 t/h.Additionally,the equipment’s overall opening of the valve is low and adjustment performance is poor.The above problems increase the overall energy consumption of the system.To eliminate the influence of climate change on the energy consumption analysis of the central heating system,its energy consumption was evaluated by combining the number of degree days and the actual heating area.Compared with the standard year,average heat and power consumptions in the same period of the heating season in the test year increases by 0.86 GJ/(104 m^(2)·℃·d)and 2.38 kW·h/(104 m^(2)·℃·d),respectively.After cleaning and replacing the main equipment,the cumulative power consumption of the central heating system during the same period of the heating season as the diagnosis time can be reduced by 16.3%and CO_(2) emissions during the entire life cycle can be reduced by 128.5 t.