| In northern China,central heating is the most common form of heating.Because of the large thermal inertia of central heating,the transient regulation response ability of the system is limited,and there are different degrees of mismatch between supply and demand and energy waste in the actual heating process.In this paper,aiming at the central heating system of a university,combined with the actual energy-saving renovation project,the operation and maintenance information is systematically investigated and analyzed from the heat source,heat inlet and user terminal,and the optimal operation strategy is put forward.The heating area of this heating system is about 240,000 square meters,and the energy-saving transformation was carried out in 2019-2020,which realized the online control of 28 thermal inlets,room temperature monitoring of all thermal inlets,and partial parameter monitoring of operation information of energy centers,boilers and pumps.The main work of this paper includes:1)Terminal room temperature monitoring information and user feedback analysis.Based on the analysis of room temperature information collected by the management and control platform,combined with user questionnaire survey,on-site temperature measurement and operation log,the room temperature distribution at all entrance ends in the actual heating process is systematically analyzed,and the representative room temperature is selected for visual push every week in combination with the analysis of repair information.Operation and maintenance personnel adjust the room temperature at different entrances to avoid the"one size fits all"adjustment method.It is found that in the first two weeks of the heating season,the repair service is concentrated in the student dormitory,and the room temperature can be kept above18℃.Considering the location of individual rooms and the individual differences of students,we can focus on the adjustment of the entrance and internal load distribution in the repair service center.In addition,the valve position adjustment time can be further optimized and adjusted according to students’work and rest time,and the valve opening can be reduced(5%～10%)at 1 pm and 23 pm.2)Operation analysis and control optimization of thermal inlet.Based on the analysis of parameter information collected by the control platform,combined with some inlet adjustment tests and regression analysis,the correlation of valve position,flow rate,load,room temperature and air temperature at different inlets is systematically analyzed,providing reference for actual operation and maintenance and further fine control.It is found that the design load is basically the same,the actual operating load of different user types is quite different,and there are obvious differences between different entrances of users of the same type,which are related to geographical location,user behavior and heat dissipation form.Parameter adjustment response analysis shows that the room temperature will slightly increase within 5 hours after the inlet flow drops,and the thermal inertia of the building leads to the lag of the room temperature change.Within 30 minutes after the opening of the valve position increases,the load will slightly increase,and then gradually stabilize:when the water supply temperature of the energy center changes,the response time of the water supply temperature at the end inlet is 6～12 minutes.Therefore,in the actual operation and regulation process of central heating,it is advisable to fully consider the ability of the end user’s room temperature change to respond to the transient response of the regulation parameters,and adjust the regulation parameters appropriately in advance to meet the end user’s heat demand and avoid the energy waste caused by excessive heating.3)Operation analysis and scheduling optimization of energy center.Based on the related parameter information of energy centers such as boiler and circulating pump operation collected by the control platform,combined with the operation log,this paper analyzes the correlation between water supply temperature,flow rate and load,and puts forward the optimal operation and scheduling strategy of boiler and circulating pump,which can provide reference for actual operation and maintenance and further fine control.Based on the analysis of boiler start-up scheduling and load rate in 2019-2021heating seasons,the principle of starting boiler capacity and number according to load range is obtained.In view of the pump operation scheduling and circulating water flow analysis of the energy center during the actual operation in the heating season of 2020-2021,considering the temperature difference between supply and return water to ensure the most unfavorable terminal room temperature and economic operation,the minimum flow is determined to be 863 m~3/h.If the energy center operates under this flow constraint condition,the water consumption will be reduced by 3,615 tons compared with the actual operation.In the heating season of 2021-2022,the operation of boiler and water pump was optimized to a certain extent.Compared with the last heating season,the water supply temperature and circulating water flow during the optimized operation period can be reduced by 18.0%and 16.8%at the maximum.In the autumn semester,the energy station operated for 77 days,and the gas consumption was1,060,437 m~3 in 2021-2022 and 1,262,306 m~3 in 2020-2021.In comparison,the gas consumption this year decreased by 16.0%,about 200,000 m~3.To sum up,in the actual operation and adjustment process of central heating system,taking into account the room temperature demand of different users at the end,the difference of thermal inlet,the thermal inertia of heating buildings,and the operation optimization and adjustment of heat source side boilers and circulating water pumps will help to ensure the heating comfort,improve the operating efficiency of boilers and water pumps,reduce the loss of pipe network,reduce the amount of gas and direct carbon emissions,and reduce the amount of electricity,water and indirect carbon emissions. |
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