A steam power cycle thermal power generation system and its process

Abstract

The invention discloses a steam power cycle thermal power generation system and a steam power cycle thermal generation technology. A water wall is connected with a turbine through a superheater and a main steam pipeline. Multiple turbine steam extraction pipelines of the turbine are used for heat exchange with a low-pressure heater and a high-pressure heater. A draught fan draws in cold air in the atmosphere and conveys the cold air into an air pre-heater, and the cold air is heated by flue gas from a hearth and a boiler high-temperature flue gas section. The amount of the flue gas from the hearth and the boiler high-temperature flue gas section is set to be matched with the amount of the cold air so that the flue gas and the cold air can have the same heat capacity flow rate in the air pre-heater. After condensed water in a condenser is directly boosted by a high-pressure condensate pump to reach the pressure of a boiler, the condensed water enters a high-pressure condensed water heater to be heated by flue gas and then enters the water wall of the boiler. The flow of the high-pressure condensed water is adjusted to be matched with the flue gas heating the high-pressure condensed water so that the heat capacity flow rate of the high-pressure condensed water to be equal with that of the flue gas. By the adoption of the steam power cycle thermal power generation system and the steam power cycle thermal generation technology, the inherent defect that cold fluid and hot fluid are different in heat capacity flow rate is overcome, the temperature difference pinch point limit is avoided, and then the temperature of the flue gas can be lowered to be low enough.

Description

technical field [0001] The invention belongs to the technical field of boilers, and in particular relates to a steam power cycle thermal power generation system and a process thereof. Background technique [0002] In the traditional steam power cycle system, the boiler completes the function of heating water, and the steam turbine completes the function of steam. An air preheater is usually used on the heating surface at the rear of the boiler. The inlet air temperature of the air preheater is determined by the atmospheric environment and is usually not adjustable. Since the heat capacity flow rate of the air is smaller than the heat capacity flow rate of the flue gas, sufficient heat transfer must be ensured The temperature difference and the reduction of the exhaust gas temperature are inherently limited, and the high exhaust gas temperature will inevitably increase the water consumption of the subsequent wet desulfurization system. In addition, due to the low air inlet t...

AI Technical Summary

Problems solved by technology

An air preheater is usually used on the heating surface at the rear of the boiler. The inlet air temperature of the air preheater is determined by the atmospheric environment and is usually not adjustable. Since the heat capacity flow rate of the air is smaller than the heat capacity flow rate of the flue gas, sufficient heat transfer must be ensured The temperature difference, the reduction of exhaust gas temperature is inherently limited, and the high exhaust gas temperature will inevitably increase the water consumption of the subsequent wet desulfurization system

In addition, due to the low air inlet temperature, in the traditional air preheater of air-flue gas heat exchange, the temperature of the heat exchange surface is usually around the middle value of the flue gas temperature and the air temperature, resulting in inevitable low-temperature corrosion and plugging Ash and other adverse effects

On the other hand, modern steam power engineering usually adopts heat recovery cycle and reheat cycle to improve cycle efficiency, but the limit of heat recovery is usually limited by the increase of boiler equipment investment or increase of exhaust gas temperature after the feed water temperature is increased, which limits Further improvement in thermal efficiency

Therefore, in summary, due to the above-mentioned shortcomings such as the limited reduction of boiler exhaust gas temperature, the influence of low-temperature corrosion and ash plugging, and the limited increase in feed water temperature and large heating surface of the regenerative cycle, although the traditional steam power cycle The cycle efficiency is improved by means of reheating and reheating, but its thermodynamic imperfection is still poor, which is significantly different from the Carnot cycle efficiency determined by the same heat source temperature-environment temperature

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