Flue gas waste heat utilization system of desulfurizing tower

Abstract

The utility model discloses a flue gas waste heat utilization system of a desulfurizing tower, which comprises an induced draft fan and the desulfurizing tower which are sequentially connected with a boiler discharge flue, a flue gas outlet of the desulfurizing tower is connected with a chimney through a pipeline, and a flue gas heat exchanger is arranged on the pipeline between the induced draft fan and the desulfurizing tower; an oxidation air inlet pipe is arranged on the desulfurizing tower, a high-temperature oxidation air pipe is arranged on an output port of the oxidation fan, an outlet of the high-temperature oxidation air pipe is connected with an air heat exchanger, an oxidation air outlet of the air heat exchanger is connected with the pipe end of the oxidation air inlet pipe, and a low-temperature condensed water inlet pipe and a medium-temperature condensed water outlet pipe are arranged on the air heat exchanger. The medium-temperature condensed water outlet pipe is connected with a heat exchange pipe inlet of the flue gas heat exchanger, and a high-temperature condensed water output pipe is arranged at a heat exchange pipe outlet of the flue gas heat exchanger.

Description

Technical Field

[0001] The utility model relates to a flue gas waste heat utilization system of a desulfurization tower, belonging to the technical field of energy saving of coal-fired boilers. Background Art

[0002] The exhaust gas from the exhaust fan of the coal-fired power unit absorbs the temperature rise of the exhaust fan, which is high in temperature and will affect the desulfurization efficiency and increase the water consumption of the desulfurization tower. Recycling the heat of the exhaust gas from the exhaust fan can not only improve the utilization efficiency of electric coal, reduce the consumption of electric coal, and reduce the production cost of the enterprise, but also improve the desulfurization efficiency and save the water consumption of the desulfurization tower, which is of great significance to promoting the realization of the carbon peak and carbon neutrality goals as scheduled.

[0003] At the same time, the oxidation fan of the coal-fired power unit is a high-pressure fan, and the outlet air temperature will rise to above 100°C. Excessive temperature will affect the safety of the oxidation fan and the desulfurization tower, and cooling is necessary. Currently, cooling water is used for cooling, but this method causes energy waste. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a flue gas waste heat utilization system of a desulfurization tower with high energy utilization rate.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: a flue gas waste heat utilization system of a desulfurization tower, comprising an induced draft fan and a desulfurization tower which are sequentially connected to the boiler exhaust duct, the flue gas outlet of the desulfurization tower is connected to the chimney through a pipeline, and a flue gas heat exchanger is arranged on the pipeline between the induced draft fan and the desulfurization tower; an oxidation air inlet pipe is arranged on the desulfurization tower, a high-temperature oxidation air duct is arranged on the output port of the oxidation fan, an air heat exchanger is connected to the outlet of the high-temperature oxidation air duct, the oxidation air outlet of the air heat exchanger is connected to the pipe end of the oxidation air inlet pipe, a low-temperature condensate inlet pipe and a medium-temperature condensate outlet pipe are arranged on the air heat exchanger, the medium-temperature condensate outlet pipe is connected to the heat exchange tube inlet of the flue gas heat exchanger, and a high-temperature condensate output pipe is arranged at the heat exchange tube outlet of the flue gas heat exchanger.

[0006] As a preferred solution, the high-temperature condensate output pipe is provided with an output branch pipe connected to the inlet of the fifth low-pressure heater of the steam turbine, and the output branch pipe is provided with a stop valve and a regulating valve.

[0007] As a preferred solution, the low-temperature condensate inlet pipe is connected to the condensate outlet of the seventh low-pressure heater of the steam turbine.

[0008] As a preferred solution, a booster pump and a control valve are provided on the low-temperature condensate inlet pipe.

[0009] As a preferred solution, the high-temperature condensate output pipe is connected to an air duct heat exchanger provided on the primary air duct at the boiler inlet to provide a heat source.

[0010] As a preferred solution, a flow control valve is provided on the medium-temperature condensate outlet pipe.

[0011] The beneficial effects of the utility model are:

[0012] This system can recycle the waste heat of the exhaust fan outlet flue gas and the heat of high-temperature oxidation air, increase the temperature of part of the condensate, exclude the low-pressure extraction steam of the steam turbine, and reduce the energy consumption of the unit; it can also reduce the flue gas temperature at the desulfurization tower inlet and improve the desulfurization efficiency; it can also reduce the oxidation air temperature and improve the safety of the oxidation fan and desulfurization tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the system composition block diagram of this system.

[0014] In the figure: 1. induced draft fan; 2. flue gas heat exchanger; 3. desulfurization tower; 4. oxidation fan; 5. air heat exchanger; 6. induced draft fan outlet flue gas; 7. desulfurization tower inlet flue gas; 8. high-temperature oxidation air duct; 9. oxidation air inlet pipe; 10. low-temperature condensate inlet pipe; 11. medium-temperature condensate outlet pipe; 12. high-temperature condensate, 13. chimney, 14. booster pump, 15. control valve, 16. stop valve, 17. regulating valve. DETAILED DESCRIPTION

[0015] The specific implementation scheme of the utility model is described in detail below in conjunction with the accompanying drawings.

[0016] like Figure 1 As shown, the flue gas waste heat utilization system of the desulfurization tower includes an induced draft fan 1 and a desulfurization tower 3 connected to the boiler exhaust duct in sequence, the flue gas outlet of the desulfurization tower 3 is connected to the chimney through a pipeline, and a flue gas heat exchanger 2 is provided on the pipeline between the induced draft fan 1 and the desulfurization tower 3; the desulfurization tower 3 is provided with an oxidation air inlet pipe 9, the output port of the oxidation fan 4 is provided with a high-temperature oxidation air duct 8, the outlet of the high-temperature oxidation air duct 8 is connected with an air heat exchanger 5, the oxidation air outlet of the air heat exchanger 5 is connected to the pipe end of the oxidation air inlet pipe 9, the air heat exchanger 5 is provided with a low-temperature condensate inlet pipe 10 and a medium-temperature condensate outlet pipe 11, and the low-temperature condensate inlet pipe 10 is connected to the condensate outlet of the seventh low-pressure heater of the steam turbine. A booster pump 14 and a control valve 15 are provided on the low-temperature condensate inlet pipe 10.

[0017] The medium-temperature condensate outlet pipe 11 is connected to the heat exchange tube inlet of the flue gas heat exchanger 2, and a high-temperature condensate output pipe 12 is provided at the heat exchange tube outlet of the flue gas heat exchanger 2. The high-temperature condensate output pipe 12 is provided with an output branch pipe connected to the inlet of the fifth low-pressure heater of the steam turbine, and the output branch pipe is provided with a stop valve 16 and a regulating valve 17. The high-temperature condensate output pipe 12 is connected to the air duct heat exchanger provided on the primary air duct at the boiler inlet to provide a heat source.

[0018] When the system is working, a flue gas heat exchanger 2 is installed at the outlet of the induced draft fan 1. After the flue gas at the outlet of the induced draft fan 1 releases heat through the flue gas heat exchanger 2, the temperature drops from 130°C to 110°C, and then enters the desulfurization tower 3; an air heat exchanger 5 is installed at the outlet of the oxidation fan. After the high-temperature oxidation air releases heat through the air heat exchanger 5, the temperature drops from 100°C to 50°C, and then enters the desulfurization tower 3; the low-temperature condensate at 40°C is heated to 85°C through the air heat exchanger 5, and then enters the flue gas heat exchanger 2 for further heating. After further heating, it becomes high-temperature condensate at 110°C and is sent to the condensate side of the steam turbine, thereby achieving the purpose of heating the condensate using the heat of the high-temperature oxidation air and the flue gas at the outlet of the induced draft fan.

[0019] The above-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A flue gas waste heat utilization system of a desulfurization tower, comprising an induced draft fan (1) and a desulfurization tower (3) connected in sequence to a boiler exhaust duct, the flue gas outlet of the desulfurization tower (3) being connected to a chimney through a pipeline, and a flue gas heat exchanger (2) being provided on the pipeline between the induced draft fan (1) and the desulfurization tower (3); characterized in that: The desulfurization tower (3) is provided with an oxidation air inlet pipe (9), the output port of the oxidation fan (4) is provided with a high-temperature oxidation air pipe (8), the outlet of the high-temperature oxidation air pipe (8) is connected to an air heat exchanger (5), the oxidation air outlet of the air heat exchanger (5) is connected to the pipe end of the oxidation air inlet pipe (9), the air heat exchanger (5) is provided with a low-temperature condensate inlet pipe (10) and a medium-temperature condensate outlet pipe (11), the medium-temperature condensate outlet pipe (11) is connected to the heat exchange pipe inlet of the flue gas heat exchanger (2), and a high-temperature condensate output pipe (12) is provided at the heat exchange pipe outlet of the flue gas heat exchanger (2).

2. The flue gas waste heat utilization system of a desulfurization tower according to claim 1, characterized in that: The high-temperature condensate output pipe (12) is provided with an output branch pipe connected to the inlet of the fifth low-pressure heater of the steam turbine, and the output branch pipe is provided with a stop valve (16) and a regulating valve (17).

3. The flue gas waste heat utilization system of a desulfurization tower according to claim 1, characterized in that: The low-temperature condensate inlet pipe (10) is connected to the condensate outlet of the seventh low-pressure heater of the steam turbine.

4. The flue gas waste heat utilization system of a desulfurization tower according to claim 1, characterized in that: The low-temperature condensate inlet pipe (10) is provided with a booster pump (14) and a control valve (15).

5. A flue gas waste heat utilization system for a desulfurization tower according to any one of claims 1 to 4, characterized in that: The high-temperature condensate output pipe (12) is connected to an air duct heat exchanger arranged on the primary air duct at the boiler inlet to provide a heat source.

6. A flue gas waste heat utilization system for a desulfurization tower according to any one of claims 1 to 4, characterized in that: The medium-temperature condensate outlet pipe (11) is provided with a flow control valve.

Images