CN212362150U - Heat supply network drainage system of circulating fluidized bed combined heat and power generation unit under cylinder cutting working condition - Google Patents

Abstract

The utility model discloses a cut hot-wire net drainage system of circulating fluidized bed combined heat and power units under jar operating mode, solved current combined heat and power units who adopts circulating fluidized bed boiler how take into account the problem of unit safe operation and the waste of avoiding heat energy under the part low pressure jar operating mode of excision. The heat of the heat supply network drainage of the heat supply initial station is exchanged to the heat supply network circulating water return water by adopting the drainage cooling heat exchanger, and then the cooled heat supply network drainage is conveyed to the heat supply network condenser for flash evaporation, so that the purpose of reducing flash steam quantity is achieved, namely, a certain amount of condensed water with lower temperature is ensured to enter the host steam exhaust device, the requirement that a host condensate pump is maintained under a normal working condition is met, the cooling effect of a slag cooler of the circulating fluidized bed boiler is also ensured, the heat of the heat supply network drainage of the heat supply initial station is exchanged to the heat supply network circulating water return water, the part of energy is fully utilized in a heat supply system, the heat supply cost is reduced, and the heat and the condensed water are subjected to new balanced distribution in the whole co-production heat supply unit.

Description

Heat supply network drainage system of circulating fluidized bed combined heat and power generation unit under cylinder cutting working condition

Technical Field

The invention relates to a cogeneration heat supply unit, in particular to a heat supply network drainage system of a circulating fluidized bed boiler generator set under the working condition of a low pressure cylinder of a cut-off part of a steam turbine in a heating period in winter.

Background

The combined heat and power generation heating unit of the circulating fluidized bed boiler is adopted, and generally operates for 4-5 months under 50% rated power generation load in the heating period in winter; in order to make the generator set achieve the purpose of low energy consumption under partial load, a power plant usually adopts an operation mode of cutting off part of low-pressure cylinders of the generator set, and the operation condition of the generator set is called as a low-pressure cylinder cutting-off condition (or called as a cylinder cutting-off condition); when the generator set operates under the low-pressure cylinder cutting working condition, the steam extraction amount of steam to the generator set is increased in the heating period, so that the amount of condensed water entering a main engine steam exhaust device of the generator set is obviously reduced, a condensed water pump of the generator set operates under a small water amount, and the efficiency of the condensed water pump is low; in addition, the boiler slag cooler in the cogeneration power generation and heat supply unit adopting the circulating fluidized bed boiler is cooled by the condensed water of the main machine, and the boiler slag cooler needs a certain amount of low-temperature condensed water to meet the cooling requirement, so that the safe operation of the boiler slag cooler is ensured; in order to solve the above requirements, the following two operation schemes are generally adopted on site, the first scheme is that the heat supply network drainage in a heat supply initial station carried by the cogeneration generating and heating unit is directly introduced into a main engine condensed water pipeline of the generator set, and the shortage of main engine condensed water is supplemented by the heat supply network drainage, but the temperature of the condensed water is increased too high due to the fact that the heat supply network drainage in the heat supply initial station is generally high, the water temperature of the condensed water is increased after the heat supply network drainage directly enters the main engine condensed water pipeline, the cooling effect of the condensed water on a boiler slag cooler is greatly reduced, and the safe operation of a slag discharge system of the circulating fluidized bed boiler is directly threatened; the second is that the drain water of the heat supply network of the heat supply initial station is firstly connected to the main engine steam exhaust device for flash evaporation, so as to achieve the purpose of reducing the drain temperature, the drain water after being cooled enters the main engine condensate system after passing through the main engine steam exhaust device, namely, the temperature of the drain water is reduced, the deficiency of the condensate water is compensated, the purposes of simultaneously improving the flow rate of the condensate water pump and meeting the cooling requirement of the slag cooler are achieved, but because the heat supply network of the heat supply initial station with higher temperature is hydrophobic, when the drain water enters the main engine steam exhaust device for flash evaporation, the defect of overlarge flash evaporation amount steam can occur, the excessive flash evaporation steam in the heat supply network steam condenser must be discharged onto an air cooling island for cooling, and the heat energy loss in the drain water of the heat supply network of the heat supply. How to ensure the safe operation of a cogeneration unit of a circulating fluidized bed boiler and avoid the loss of heat energy of a heating system becomes a technical problem to be solved on site.

Disclosure of Invention

The invention provides a heat supply network drainage system of a circulating fluidized bed cogeneration unit under a cylinder cutting working condition, and solves the technical problems of considering safe operation of the cogeneration unit and avoiding waste of heat energy under the working condition of cutting off a part of low pressure cylinders in the conventional cogeneration unit adopting a circulating fluidized bed boiler.

The invention solves the technical problems by the following technical scheme:

the general concept of the invention is: the heat of the heat supply network drainage of the heat supply initial station is exchanged to the circulating water return water of the heat supply network by adopting the drainage cooling heat exchanger, and then the cooled heat supply network drainage is conveyed to the heat supply network condenser for flash evaporation, so that the flash steam quantity is reduced, namely, a certain amount of condensed water with lower temperature is ensured to enter the main engine steam exhaust device, the requirement that a main engine condensate pump is maintained under a normal working condition is met, the cooling effect of a slag cooler of the circulating fluidized bed boiler is ensured, the cooling device can safely operate, the heat of the heat supply network drainage of the heat supply initial station is exchanged to the circulating water return water of the heat supply network, the part of energy is fully utilized in a heat supply system, the waste is avoided, the heat supply cost is reduced, and the heat and the condensed water are subjected to new balanced distribution in the whole co-production heat.

A heat supply network drainage system of a circulating fluidized bed cogeneration unit under a cylinder cutting working condition comprises a circulating fluidized bed cogeneration unit host exhaust device, a circulating fluidized bed cogeneration unit host condensation water pipeline, a heat supply network condenser, a heat supply first station heat supply network drainage conveying pipeline, a heat supply first station water return pipeline, a heat supply network circulating water return pipeline and a drainage cooling heat exchanger, wherein a flash evaporation spraying device and a heat supply network condenser output water pipeline are arranged on the heat supply network condenser, the other end of the heat supply network condenser output water pipeline is communicated with the circulating fluidized bed cogeneration unit host exhaust device, a heat exchange cooling water conveying inlet on the drainage cooling heat exchanger is communicated with the heat supply first station heat supply network drainage conveying pipeline, a heat exchange cooling water outlet on the drainage cooling heat exchanger is connected with a heat supply network drainage cooling water conveying pipeline, the other end of the heat supply network drainage cooling water conveying pipeline is communicated with an input water port of the flash evaporation spraying device, the heat exchange temperature rise output water port on the drain cooling heat exchanger is communicated with a heat supply first station water return pipeline, a heat supply network circulating water return once temperature rise water delivery pipeline is connected to the heat exchange temperature rise water delivery port on the drain cooling heat exchanger, the other end of the heat supply network circulating water delivery pipeline after once temperature rise water delivery pipeline is communicated with a heat supply network condenser heat exchange water output port on a heat supply network condenser, and a heat supply network condenser heat exchange water input port on the heat supply network condenser is communicated with the heat supply network circulating water return pipeline.

A tee joint is connected in series on a drainage conveying pipeline of a heat supply network of a heat supply initial station, and a third output port of the tee joint is communicated with a condensed water pipeline of a main machine of a circulating fluidized bed cogeneration unit through a valve; the temperature of the first heat supply station heat supply network drainage in the first heat supply station heat supply network drainage conveying pipeline is 70-80 ℃, the temperature of the heat supply network drainage after heat exchange and cooling in the water conveying pipeline after the heat supply network drainage is cooled is 50-60 ℃, and the temperature of the output water in the output water pipeline of the heat supply network condenser is 30-40 ℃.

The invention has the advantages that the two-stage cooling device for draining the heat supply network is arranged on the existing heat supply network drainage system, so that the drainage temperature of the heat supply network is reduced, the running flow of the condensed water pump of the main machine is increased, the sensible heat of the drainage of the heat supply network is recovered, and the running reliability of the unit is improved while the energy utilization rate of the heat supply system is increased.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Detailed Description

The invention is described in detail below with reference to the accompanying drawings:

a heat supply network drainage system of a circulating fluidized bed cogeneration unit under a cylinder cutting working condition comprises a circulating fluidized bed cogeneration unit host exhaust device 10, a circulating fluidized bed cogeneration unit host condensation water pipeline 12, a heat supply network condenser 5, a heat supply head station heat supply network drainage conveying pipeline 1, a heat supply head station water return pipeline 3, a heat supply network circulating water return pipeline 4 and a drainage cooling heat exchanger 2, wherein a flash evaporation spraying device 7 and a heat supply network condenser output water pipeline 9 are arranged on the heat supply network condenser 5, the other end of the heat supply network condenser output water pipeline 9 is communicated with the circulating fluidized bed cogeneration unit host exhaust device 10, a heat exchange cooling water conveying inlet on the drainage cooling heat exchanger 2 is communicated with the heat supply head station heat supply network drainage conveying pipeline 1, a heat exchange cooling water outlet on the drainage cooling heat exchanger 2 is connected with a heat supply network drainage cooling water conveying pipeline 8, the other end of the water delivery pipeline 8 after the drainage and cooling of the heat supply network is communicated with the water input port of the flash evaporation spraying device 7, the heat exchange temperature rise output water port on the drainage and cooling heat exchanger 2 is communicated with the heat supply initial station water return pipeline 3, the heat exchange temperature rise water delivery port on the drainage and cooling heat exchanger 2 is connected with a water delivery pipeline 6 after the primary temperature rise of the heat supply network circulating backwater, the other end of the water delivery pipeline 6 after the primary temperature rise of the heat supply network circulating backwater is communicated with the heat supply network condenser heat exchange water output port on the heat supply network condenser 5, and the heat supply network condenser heat exchange water input port on the heat supply network condenser 5 is communicated with the heat supply network circulating water.

A tee joint 13 is connected in series on the heat supply first station heat supply network drainage conveying pipeline 1, and a third output port of the tee joint 13 is communicated with a circulating fluidized bed cogeneration unit main machine condensation water pipeline 12 through a valve 11; the temperature of the heat supply initial station heat supply network drainage in the heat supply initial station heat supply network drainage conveying pipeline 1 is 70-80 ℃, the temperature of the heat supply network drainage after heat exchange and cooling in the water conveying pipeline 8 after the heat supply network drainage is cooled is 50-60 ℃, and the temperature of the output water in the heat supply network condenser output water pipeline 9 is 30-40 ℃.

In the heating period in winter, a low-pressure cylinder of a cogeneration heat supply generator set is partially cut off, a large amount of steam is pumped into a heat exchanger of a heat supply initial station when the generator set works in the working state of the low-pressure cylinder, urban hot water is heated, the temperature of heat supply initial station heat supply network drain output by the heat exchanger of the heat supply initial station is about 70-80 ℃, the heat supply initial station heat supply network drain is conveyed into a drain cooling heat exchanger 2 through a heat supply initial station heat supply network drain conveying pipeline 1 and exchanges heat with heat supply network circulating return water input into a drain cooling heat exchanger 2 in a water conveying pipeline 6 after the heat supply network circulating return water is heated for one time, the temperature of the heat supply network drain after heat exchange is about 50-60 ℃, the water conveying pipeline 8 enters a flash evaporation spraying device 7 after the heat supply network drain is cooled for flash evaporation, and the temperature of the flash evaporated heat supply network drain is 50-60 ℃, the amount of steam generated after flash evaporation is not very large, the steam generated after flash evaporation does not need to be discharged into an air cooling island for cooling, and meanwhile, the temperature of output water in an output water pipeline 9 of a heat supply network condenser is kept at 30-40 ℃, so that the requirement of a unit on the temperature of condensed water is well met. The urban heat supply network circulating water backwater returned by the heat supply network circulating water backwater pipeline 4 is firstly heated by the heat supply network condenser 5 in the first stage, then enters the drain cooling heat exchanger 2 to be subjected to second-stage heating by the heat supply first station heat supply network drain, and finally enters the heat supply first station heat exchanger to be subjected to third-stage heating, so that the heat energy is fully utilized, and the heat supply cost is reduced.

Claims (2)

1. A heat supply network drainage system of a circulating fluidized bed cogeneration unit under a cylinder cutting working condition comprises a circulating fluidized bed cogeneration unit host exhaust device (10), a circulating fluidized bed cogeneration unit host condensation water pipeline (12), a heat supply network condenser (5), a heat supply first station heat supply network drainage conveying pipeline (1), a heat supply first station water return pipeline (3), a heat supply network circulating water return pipeline (4) and a drainage cooling heat exchanger (2), wherein a flash evaporation spraying device (7) and a heat supply network condenser output water pipeline (9) are arranged on the heat supply network condenser (5), the other end of the heat supply network condenser output water pipeline (9) is communicated with the circulating fluidized bed cogeneration unit host exhaust device (10), and the heat supply network drainage system is characterized in that a heat exchange cooling water conveying inlet on the drainage cooling heat exchanger (2) is communicated with the heat supply first station heat supply network drainage conveying pipeline (1), a heat exchange cooling output water port on the hydrophobic cooling heat exchanger (2) is connected with a heat supply network hydrophobic cooling back water delivery pipeline (8), the other end of the heat supply network hydrophobic cooling back water delivery pipeline (8) is communicated with an input water port of a flash evaporation spraying device (7), a heat exchange heating output water port on the hydrophobic cooling heat exchanger (2) is communicated with a heat supply first station water return pipeline (3), a heat supply network circulating water returning once heating back water delivery pipeline (6) is connected to a heat exchange heating input water port on the hydrophobic cooling heat exchanger (2), the other end of the heat supply network circulating water returning once heating back water delivery pipeline (6) is communicated with a heat supply network condenser heat exchange water output port on a heat supply network condenser (5), and a heat supply network condenser heat exchange water input port on the heat supply network condenser (5) is communicated with a heat supply network circulating water return pipeline (4).

2. The heat supply network drainage system of the circulating fluidized bed cogeneration unit under the cylinder cutting working condition according to claim 1, characterized in that a tee joint (13) is connected in series on the heat supply initial station heat supply network drainage conveying pipeline (1), and a third output port of the tee joint (13) is communicated with a condensation water pipeline (12) of a main machine of the circulating fluidized bed cogeneration unit through a valve (11); the temperature of the heat supply initial station heat supply network drainage in the heat supply initial station heat supply network drainage conveying pipeline (1) is 70-80 ℃, the temperature of the heat supply network drainage after heat exchange and cooling in the heat supply network drainage cooling water conveying pipeline (8) is 50-60 ℃, and the temperature of the output water in the heat supply network condenser output water pipeline (9) is 30-40 ℃.

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