Full recovery fuel combustion steam power cycle thermal power generation system and its technology

Abstract

The invention discloses an all-regenerated fuel combustion steam power cycle thermal power generation system. A water cooling wall is connected with a steam turbine through a connected superheater and a main steam pipe; a waste steam pipe of the steam turbine is connected with an inlet of a steam condenser; an outlet of the steam condenser is connected with an inlet of a condensation water pump and an inlet of a high-pressure condensation water pump; an outlet of the condensation water pump is connected with an inlet of the water cooling wall through a low-pressure heater, a water feeding pump and a high-pressure heater connected in sequence; an outlet of the high-pressure condensation water pump is connected with the inlet of the water cooling wall after exchanging heat with a high-pressure condensation water heater; an outlet of a fan is connected with an air heater; exhausted air of the air heater serves as secondary air; the secondary air and primary air are fed in a hearth along with a fuel; and multiple steam turbine exhaust pipelines are respectively used for exchanging heat with the high-pressure condensation water heater, the low-pressure heater, the high-pressure heater and the air heater. The all-regenerated fuel combustion steam power cycle thermal power generation system overcomes inherent defects of different heat capacity flow rates of cold and hot fluids, prevents the temperature difference pinch point limit, and can reduce smoke to reach an enough low temperature.

Description

technical field [0001] The invention belongs to the technical field of boilers, and in particular relates to a fuel combustion steam power cycle thermal power generation system with total heat recovery and its technology. 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. I...

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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

In the traditional air preheater, both sides of the heating surface are gas. In addition to the low-temperature corrosion problem, it is difficult to deal with, and the heat transfer enhancement of the heating surface is also difficult.

The boiler system used in the traditional thermodynamic cycle, the SCR denitrification under different loads is usually affected by the temperature change of the location of the SCR catalyst, which is difficult to control

Therefore, in summary, due to the above-mentioned disadvantages such as the limited reduction of boiler exhaust gas temperature, the influence of low-temperature corrosion and ash plugging, which are unfavorable to the operation of SCR, as well as the limited increase in the temperature of the regenerative cycle feed water and the large heating surface, the traditional Although the steam power cycle adopts reheating and reheating methods to improve cycle efficiency, its thermodynamic imperfection is still relatively poor, which is significantly different from the Carnot cycle efficiency determined by the same heat source temperature-environment temperature

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