Analysis Of A Municipal District Heating System And Applicable Technologies For Upgrading

In order to meet the clean heating in the urban area in winter,the traditional coal-fired regional central heating system is paying more and more attention to energy saving and environmental protection while ensuring the comfort of the users.Based on industry-university-research cooperation and engineering practice,a survey and analysis of a traditional municipal coal-fired central heating system in Xi'an is made.Preliminary consideration is given to the applicable technology of upgrading existing system.In this paper,the actual heating system in Xi'an is investigated and analyzed with reference to the national standard(GB/T 50893-2013)for the operation of the heating season of 2016~2017.The results show that the level of water pipe network system than(2.36%)far exceeds the national standard limit value(1%),can objectively reflect the operation level of the system is relatively low;coal consumption,power consumption,heat consumption in the standard range,but should be combined with the local climate conditions and objective analysis,the average outdoor temperature is higher than that of Xi'an district heating applications the scale from other northern city(such as Beijing,Harbin,etc.).The leakage of the pipe network seriously leads to the large amount of water supply in the system.In this case,for heating during a pipe network pressure fluctuation abnormal pipe uses artificial positioning trap.At present,the risk prediction and evaluation of pipeline leakage are mostly concentrated in gas pipeline,and the fuzzy analytic hierarchy process is used more.Combined with literature research and actual case history data,4 factors,such as pipeline property,pipeline perforation,pipeline fracture and equipment failure,are selected as risk factors for leakage.Fuzzy analytic hierarchy process is applied to establish risk evaluation model for heating network leakage.In this paper,three typical cases of representative easy leakage pipe(valve well position)verification model are selected,and the evaluation results are basically consistent with the actual situation.It is possible for the whole pipeline network to carry out the risk assessment of the leaking system by using the model system,and protect the pipeline with high risk level ahead of schedule,so as to reduce the amount of water supply in the first stage pipe network during heating.The greater the resistance of the heating system,the greater the power consumption of the circulating water pump.The local resistance of heating network usually occupies a considerable proportion in the total resistance,and the pipe tees are one of the most important local components.In this paper deal with a centralized heating pipe network system,analysed the numerical simulation of the large diameter pipe tees(?400 mm)through the confluence and resistance characteristics.The results show that the local drag coefficient decreases with the decrease of q,Re and d,and decreases with the decrease of the angle between tubes,and d>0.8 and Re>4.8×10~5 tend to remain unchanged.Therefore,the rational selection of the pipe tees diameter ratio can significantly reduce the pipe network resistance,and the higher Reynolds number of the pipe can improve the efficiency of the pipe network.The technology and application of district heating and intelligent heating network are investigated.In view of the actual cases,a preliminary suggestion for upgrading and upgrading existing systems is put forward from the aspects of heat source,heat network and thermal user level.