Thermal Economical Analysis On Different Heating Modes Of Direct Air Cooling System

The weather in north China is quite harsh and the environment temperature is very low in winter, so it has a relatively greater demand for heating, and cogeneration can also improve the comprehensive efficiency of power supply unit more effectively. Air cooling thermal power plant is generally used in the north region of China. So the study of air cooling units of different heating modes on economic operation of units or heating transformation has a profound significance.This paper first analyzes various existing heating modes and new heating modes of the direct air cooling power station unit, mainly includes:high back pressure heating mode, the steam exhaust absorption heat pump and electric driven heat pump heating mode. Analyzing and comparing the different heating modes between advantages and disadvantages as well as economical difference. Take 330 MW direct air-cooling unit for example, through specific formula derivation, get the result of coal consumption savings of different heating modes, combined with the first law of thermodynamics analysis methods, assumes that benefits section is due to electricity, high back pressure heating way coal saving consumption rate is 10.2 g/(kW-h)more than extraction steam heating method, generating heating consumption rate reduced 611.34 kJ/(kW·h) than direct extraction steam heating method, power generation efficiency increased 9.07%; When the steam exhaust absorption heat pump’s COP is 2.4, Steam exhaust absorption heat pump heating way coal saving consumption rate is 6.48 g/(kW·h)) more than extraction steam heating method, generating heating consumption rate reduced 453.71 kJ/(kW·h) than direct extraction steam heating method, power generation efficiency increased 6.51%; Although Electric heat pump’s COP is 3.6, because of the large coal consumption, electric driven heat pump heating mode still consume 4175.5 kg/h more than extraction steam heating mode.In this paper, through the analysis of direct air cooling unit thermal efficiency as well as their advantages and disadvantages of different heating systems, draw the conclusion that direct extraction steam heating mode is extensive on the adjusting range, suitable for load stability area; High back pressure heating mode is suitable for high heating demand, load stability and best used for the heating peak area; Steam exhaust absorption heat pump and electric heat pump heating application is flexible, could be selected in combination with the practical situation of different regions. This article provides reference basis and theoretical guidance for direct air cooling unit selection in winter heating or heating transformation.