CN211146548U - A system for improving boiler efficiency by utilizing low temperature waste heat of flue gas - Google Patents

Abstract

The utility model provides a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas, comprising a coal-fired boiler, a dust collector, a wet desulfurization tower, a flash tower, an ejector and a steam turbine, wherein the flue gas outlet of the coal-fired boiler is The inlet of the dust collector is connected, the outlet of the dust collector is connected to the bottom inlet of the wet desulfurization tower, the desulfurization slurry outlet of the bottom of the wet desulfurization tower is connected to the inlet of the flash tower; the cold slurry outlet of the flash tower is connected to the top of the wet desulfurization tower. The cold slurry inlet is connected; the negative pressure steam outlet of the flash tower is connected with the steam inlet of the ejector; the steam outlet of the coal-fired boiler is connected with the inlet of the steam turbine, and a steam extraction port is arranged in the middle of the steam turbine, and the steam extraction port is connected with the ejector. The extraction steam inlet and the ejector outlet are connected to the air inlet of the coal-fired boiler; the utility model has a simple structure, and can achieve the purpose of deep recovery of flue gas waste heat by recovering the heat of the desulfurization slurry in the wet desulfurization tower, thereby improving energy utilization efficiency.

Description

A system for improving boiler efficiency by utilizing low temperature waste heat of flue gas

technical field

The utility model belongs to the field of energy saving and emission reduction of thermal power generation, in particular to a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas.

Background technique

At present, most coal-fired cogeneration units have generally adopted a variety of energy-saving measures. The cold-end losses are basically eliminated. After the energy-saving potential is greatly reduced, the exhaust gas loss accounts for the largest part of the boiler losses. The waste heat of flue gas is recovered to reduce the temperature of exhaust gas and reduce the loss of exhaust gas, which can effectively improve the energy utilization efficiency of the unit. The waste heat recovery of flue gas mainly adopts the method of partition heat exchanger. Since coal-fired flue gas contains ash and acid gas, it is easy to cause wear and corrosion of heat exchanger, and the reliability of equipment is mostly poor.

The wet desulfurization slurry is flashed, and the desulfurization slurry is introduced into the flash tower in the negative pressure state. The flashing process occurs, and a large amount of negative pressure flash steam is generated. The clean negative pressure flash steam passes through the condenser or heat pump and other equipment. , the condensation heat release is completed, and the heat recovery and utilization can be realized, and the moisture formed by the condensation of water vapor can effectively reduce the overall water consumption of the unit. Due to the evaporative cooling principle of flash evaporation, the temperature of the slurry is reduced, and the cooled desulfurization slurry is used to spray the flue gas to reduce the temperature and water content of the flue gas, and to eliminate the visual pollution of white plumes.

In addition, after injecting water vapor or water into the combustion air, the moist air mixture enters into combustion equipment such as gas turbines and boilers for combustion, which can reduce the generation of thermal NOx during the combustion process.

However, the high-temperature flue gas of the existing coal-fired cogeneration unit is not fully utilized, resulting in waste of resources.

SUMMARY OF THE INVENTION

The purpose of this utility model is to provide a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas, which can indirectly recover waste heat of flue gas after wet desulfurization, improve boiler efficiency, reduce NOx emission, reduce the water vapor content in flue gas, and recover Condensate water, eliminate the visual pollution phenomenon of white smoke plume.

In order to achieve the above-mentioned purpose, the technical scheme that the utility model adopts is:

The utility model provides a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas, comprising a coal-fired boiler, a dust collector, a wet desulfurization tower, a flash tower, an ejector and a steam turbine, wherein the flue gas outlet of the coal-fired boiler is The inlet of the dust collector is connected, the outlet of the dust collector is connected to the bottom inlet of the wet desulfurization tower, the desulfurization slurry outlet of the bottom of the wet desulfurization tower is connected to the inlet of the flash tower; the cold slurry outlet of the flash tower is connected to the top of the wet desulfurization tower. The cold slurry inlet is connected; the negative pressure steam outlet of the flash tower is connected with the steam inlet of the ejector; the steam outlet of the coal-fired boiler is connected with the inlet of the steam turbine, and a steam extraction port is arranged in the middle of the steam turbine, and the steam extraction port is connected with the ejector. The extraction steam inlet and the ejector outlet are connected to the air inlet of the coal-fired boiler.

Preferably, an induced draft fan is provided between the outlet of the dust collector and the bottom inlet of the wet desulfurization tower.

Preferably, a first slurry pump is provided between the bottom desulfurization slurry outlet of the wet desulfurization tower and the inlet of the flash tower.

Preferably, the top of the wet desulfurization tower is provided with a flue gas outlet, and the flue gas outlet is connected with a chimney.

Preferably, a second slurry pump is provided between the cold slurry outlet of the flash tower and the cold slurry inlet of the top of the wet desulfurization tower.

Preferably, the negative pressure steam outlet of the flash tower is also connected with a condenser; the spent steam outlet provided on the steam turbine is connected with a condenser.

Preferably, a compressor is provided between the outlet of the ejector and the air inlet of the coal-fired boiler.

Compared with the prior art, the beneficial effects of the present utility model are:

The utility model provides a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas, which can achieve the purpose of deep recovery of waste heat of flue gas by recovering the heat of desulfurization slurry in a wet desulfurization tower, thereby improving energy utilization efficiency; The exhaust gas is sent to the air inlet of the coal-fired boiler and mixed with air, which increases the moisture content of the air entering the boiler and reduces the oxygen content of the air, which reduces the absolute combustion temperature of the pulverized coal flame in the boiler, thereby reducing the generation of NOx; The flash evaporator can extract a large amount of water vapor from the desulfurization slurry by flashing, and the condensed water formed after the condensation of the water vapor is of good quality, which can be used as water supply for the power plant system to reduce the water consumption of the power plant; after the desulfurization slurry is flashed, the desulfurization slurry is realized. The evaporative cooling of the cold slurry can greatly reduce the temperature and moisture content of the flue gas leaving the desulfurization tower after spraying the flue gas with the cold slurry, and realize the purpose of eliminating the visual pollution of white smoke plumes; the utility model has the advantages of simple structure, low cost and strong versatility.

Description of drawings

Figure 1 is a schematic diagram of the system structure involved in the present invention.

Detailed ways

The present utility model will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the utility model provides a system for improving boiler efficiency by utilizing low-temperature waste heat of flue gas, including a coal-fired boiler 1, a dust collector 2, an induced draft fan 3, a wet desulfurization tower 4, a first slurry pump 5, The flash tower 6, the second slurry pump 7, the chimney 8, the ejector 9, the steam turbine 10, the compressor 11 and the condenser 12, wherein the flue gas outlet of the coal-fired boiler 1 is connected to the inlet of the dust collector 2, and the dust collector 2 The outlet is connected to the bottom inlet of the wet desulfurization tower 4 through the induced draft fan 3, and the desulfurization slurry outlet at the bottom of the wet desulfurization tower 4 is connected to the inlet of the flash tower 6 through the first slurry pump 5; the flue gas at the top of the wet desulfurization tower 4 is connected. Connect chimney 8.

The cold slurry outlet of the flash tower 6 is connected to the cold slurry inlet of the top of the wet desulfurization tower 4 through the second slurry pump 7 .

The negative pressure steam outlet of the flash tower 6 is divided into two paths, one is connected to the inlet of the condenser 12 , which is provided with a condensed water outlet; the other is connected to the steam inlet of the ejector 9 .

The steam outlet of the coal-fired boiler 1 is connected to the inlet of the steam turbine 10. The steam turbine 10 is provided with a steam extraction port in the middle. Air inlet of boiler 1.

The exhausted steam outlet provided on the steam turbine 10 is connected to the inlet of the condenser 12 .

The working process of the system:

The flue gas generated by the coal-fired boiler 1 passes through the dust collector 2, and then is sent to the wet desulfurization tower 4 by the induced draft fan 3. The flue gas in the wet desulfurization tower 4 undergoes a desulfurization reaction with the desulfurization slurry sprayed from the top, and the temperature is lowered at the same time. Humidify.

The desulfurization slurry at the bottom outlet of the wet desulfurization tower 4 is sent to the flash tower 6 through the first slurry pump 5, and the desulfurization slurry in the flash tower 6 undergoes an evaporative cooling process to flash out negative pressure steam, and at the same time cool down to become a cold slurry. The slurry is sent to the wet desulfurization tower 4 through the second slurry pump 7, and sprayed from the top into the tower. After spraying and desulfurization reaction, the flue gas passes through the mist eliminator, leaves the wet desulfurization tower 4, and is sent to the chimney 8. into the atmosphere.

The steam generated by the coal-fired boiler 1 is sent to the steam turbine 10 to generate electricity. A steam extraction port is arranged in the middle of the steam turbine 10, and the extracted steam is sent to the ejector 9, and negative pressure is generated in the ejector 9, and the exhausted steam of the steam turbine 10 is sent to the condensing device. Steamer 12.

A part of the negative pressure steam generated by the flash tower 6 enters the ejector 9 under the action of the pressure difference, and is mixed with the extraction steam of the steam turbine and then heated by the compressor 11 and mixed into the air of the coal-fired boiler 1; A portion of the negative pressure steam is condensed in the condenser 12 to form condensed water.

Claims (7)

1. A system for improving boiler efficiency by using low-temperature waste heat of flue gas is characterized by comprising a coal-fired boiler (1), a dust remover (2), a wet desulphurization tower (4), a flash tower (6), an ejector (9) and a steam turbine (10), wherein a flue gas outlet of the coal-fired boiler (1) is connected with an inlet of the dust remover (2), an outlet of the dust remover (2) is connected with a bottom inlet of the wet desulphurization tower (4), and a bottom desulphurization slurry outlet of the wet desulphurization tower (4) is connected with an inlet of the flash tower (6); a cold slurry outlet of the flash tower (6) is connected with a cold slurry inlet at the top of the wet desulphurization tower (4); a negative pressure steam outlet of the flash tower (6) is connected with a steam inlet of the ejector (9); the steam outlet of the coal-fired boiler (1) is connected with the inlet of a steam turbine (10), the middle part of the steam turbine (10) is provided with a steam extraction port, the steam extraction port is connected with the steam extraction inlet of an ejector (9), and the outlet of the ejector (9) is connected with the air inlet of the coal-fired boiler (1).

2. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein an induced draft fan (3) is arranged between the outlet of the dust remover (2) and the bottom inlet of the wet desulphurization tower (4).

3. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein a first slurry pump (5) is arranged between the outlet of the bottom desulfurization slurry of the wet desulfurization tower (4) and the inlet of the flash tower (6).

4. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein a flue gas outlet is arranged at the top of the wet desulphurization tower (4), and a chimney (8) is connected to the flue gas outlet.

5. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein a second slurry pump (7) is arranged between the cold slurry outlet of the flash tower (6) and the cold slurry inlet at the top of the wet desulphurization tower (4).

6. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein a condenser (12) is further connected to a negative pressure steam outlet of the flash tower (6); and a dead steam outlet arranged on the steam turbine (10) is connected with a condenser (12).

7. The system for improving the efficiency of the boiler by utilizing the low-temperature waste heat of the flue gas as claimed in claim 1, wherein a compressor (11) is arranged between the outlet of the ejector (9) and the air inlet of the coal-fired boiler (1).

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