CN118622414A - Zero emission power generation system and method based on open evaporation absorption sewage purification technology - Google Patents

Abstract

The present invention discloses a zero-emission power generation system and method based on open evaporation absorption sewage purification technology. The disclosed zero-emission power generation system includes a fresh air heater, a heat and mass generating tower, a heat and mass absorbing tower, a wet desulfurization tower, a clean water spraying tower, a boiler, a circulating sewage heater, a regenerator, an evaporation crystallizer and a steam turbine. The fresh air heater heats the incoming fresh air, the heat and mass generating tower is used to generate high-humidity air to enter the heat and mass absorbing tower, the wet desulfurization tower is used to remove sulfur and other acidic harmful substances in the flue gas generated by the boiler, the clean water spraying tower is used to cool the gas, and the boiler and the steam turbine use high-temperature steam to generate electricity for the generator. The system organically combines the flue gas circulation, wet desulfurization, etc. with the sewage circulation and clean water circulation of the open evaporation absorption sewage purification technology to achieve comprehensive optimization of thermal, water balance and pollutant balance.

Description

Zero emission power generation system and method based on open evaporation absorption sewage purification technology

Technical Field

The present invention relates to the technical field of coal-fired power generation, and in particular to a zero-emission power generation system and method based on an open evaporation absorption sewage purification technology.

Background Art

Today, coal-fired power plants, as one of the main sources of energy supply, play a key role in meeting global energy demand. However, it is accompanied by a large amount of wastewater discharge problems, especially the discharge of desulfurization wastewater. The treatment of desulfurization wastewater from coal-fired power plants faces many challenges and difficulties. First, traditional wastewater treatment technologies have problems such as high treatment costs, low treatment efficiency, and complex treatment processes, making it difficult to achieve efficient removal and resource utilization of harmful substances in wastewater. Secondly, wastewater discharge standards are becoming increasingly stringent, requiring wastewater discharge to meet zero or near-zero emission requirements. Traditional treatment technologies often find it difficult to meet this standard, which makes coal-fired power plants face the pressure of increasing difficulty in wastewater treatment.

Therefore, developing a highly efficient, low-cost, zero-emission coal-fired power plant desulfurization wastewater treatment technology with no secondary disasters has important practical application value and market promotion prospects.

In view of this, the present invention is proposed.

Summary of the invention

The purpose of the present invention is to provide a zero-emission power generation system and method based on open evaporation absorption sewage purification technology. The power generation system organically combines smoke and air circulation, wet desulfurization, etc. with sewage circulation and clean water circulation of open evaporation absorption sewage purification technology to achieve comprehensive optimization of thermal, water balance and pollutant balance.

The present invention is achieved in that:

In a first aspect, the present invention provides a zero-emission power generation system based on open evaporation absorption sewage purification technology, including a fresh air heater, a heat and mass generating tower, a heat and mass absorbing tower, a wet desulfurization tower, a clean water spray tower, a boiler, a circulating sewage heater, a regenerator, an evaporation crystallizer and a steam turbine;

The fresh air heater has a fresh air inlet and a fresh air outlet, and the fresh air outlet is connected to the air inlet at the bottom of the heat and mass generating tower and the air inlet of the boiler through a pipeline;

The air outlet at the top of the heat and mass generating tower is connected to the air inlet at the bottom of the heat and mass absorbing tower through a pipeline, and the air outlet at the top of the heat and mass absorbing tower is connected to the air inlet at the bottom of the heat and mass generating tower through a pipeline;

The liquid outlet at the bottom of the heat and mass absorption tower is connected to the liquid inlet at the top of the heat and mass absorption tower through a pipeline passing through the regenerator, and the circulating purified water of the heat and mass absorption tower provides a heat source for the regenerator;

The boiler is connected to the steam turbine, and the steam extraction port of the steam turbine is connected to the circulating sewage heater through a pipeline to provide a heat source for the circulating sewage heater;

The smoke exhaust port of the boiler is connected to the smoke inlet at the bottom of the wet desulfurization tower, the air outlet at the top of the wet desulfurization tower is connected to the air inlet at the bottom of the clean water spray tower through a pipeline, and the air outlet at the top of the thermal mass absorption tower is connected to the air inlet at the bottom of the clean water spray tower through a pipeline;

The liquid discharge port at the bottom of the clean water spray tower is connected to the liquid inlet at the top of the clean water spray tower and the liquid inlet at the top of the wet desulfurization tower through a pipeline, and the liquid outlet at the bottom of the wet desulfurization tower is connected to the liquid inlet at the top of the wet desulfurization tower and the liquid inlet at the top of the heat and mass generating tower through a pipeline;

The liquid outlet at the lower part of the heat and mass generating tower is connected to the liquid inlet at the upper part of the heat and mass generating tower through a pipeline that passes through a heat regenerator and a circulating sewage heater in sequence. The circulating sewage of the heat and mass generating tower is heated by the heat regenerator and the circulating sewage heater. The liquid outlet at the lower part of the heat and mass generating tower is connected to the inlet of the evaporator crystallizer through a pipeline; the steam extraction port of the steam turbine is connected to the evaporator crystallizer through a pipeline to provide a heat source for the evaporator crystallizer; the boiler includes an air preheater, and the fresh air outlet of the fresh air heater is connected to the air preheater through a pipeline. The fresh air enters the boiler for combustion after being heated by the air preheater.

In an optional embodiment, the boiler includes a dust collector, which is connected to the air preheater, and the dust collector is connected to the smoke inlet at the bottom of the wet desulfurization tower. The flue gas discharged from the boiler is processed by the dust collector and the air preheater in sequence and then enters the wet desulfurization tower.

In an optional embodiment, the power generation system also includes an economizer, which is arranged on the pipeline connecting the air preheater and the wet desulfurization tower. The flue gas exhausted by the boiler enters the wet desulfurization tower through the dust collector, the air preheater and the economizer in sequence.

In an optional embodiment, the power generation system further comprises a deoxygenated high pressure heating system, a desalted water heater, a low pressure heater and a condenser;

The deaerator and high-pressure heating system includes a deaerator and a high-pressure heater;

The deaeration high-pressure heating system is connected to the boiler;

The exhaust port of the steam turbine is connected to the high-pressure heater and the low-pressure heater through a pipeline to provide a heat source for the high-pressure heater and the low-pressure heater;

The condensate outlet of the circulating sewage heater is connected to the deaeration high-pressure heating system through a pipeline, and the condensate discharged from the circulating sewage heater enters the deaeration high-pressure heating system;

The condensed water outlet after the evaporation crystallizer is connected to the deoxygenation high-pressure heating system through a pipeline, and the condensed water discharged from the evaporation crystallizer enters the deoxygenation high-pressure heating system;

The condenser, desalted water heater, low-pressure heater, economizer and deaeration high-pressure heating system are connected in sequence; the condenser is connected to the steam turbine through a pipeline, and the exhaust steam of the steam turbine is cooled down to condensed water through the condenser. The condensed water is heated in sequence by the desalted water heater, low-pressure heater and economizer and then enters the deaeration high-pressure heating system;

The condensate entering the deaeration high-pressure heating system has its oxygen removed by the deaerator, and then is heated and pressurized by the high-pressure heater before entering the boiler for vaporization.

In an optional embodiment, the power generation system further includes a flue gas waste heat exchanger, and the pipeline connecting the liquid discharge port at the lower part of the clean water spray tower and the liquid inlet at the upper part of the clean water spray tower passes through the flue gas waste heat exchanger;

The flue gas waste heat exchanger is connected to the desalted water heater through an intermediate water circulation pipeline, and the circulating clean water from the clean water spray tower provides a heat source for the desalted water heater through the flue gas waste heat exchanger.

In an optional embodiment, the flue gas waste heat exchanger is connected to the fresh air heater via an intermediate water circulation pipeline, and the circulating clean water from the clean water spray tower provides a heat source for the fresh air heater via the flue gas waste heat exchanger.

In a second aspect, the present invention provides a coal-fired power generation method, which is implemented using a power generation system as described in any of the aforementioned embodiments.

The present invention has at least the following beneficial effects:

1. In the open evaporation absorption sewage purification system, a part of the heated fresh air is blown in. The fresh air has a lower moisture content, which makes the generation in the generation tower more intense. At the same time, a part of the exhaust gas at the top of the heat absorption tower with the lowest temperature in the air circulation is mixed into the flue after desulfurization to maintain the balance of the air circulation gas volume. The heat of this part of the exhaust gas is recovered together with the exhaust gas after desulfurization as waste heat, without waste;

2. Solve the problems of desulfurization water replenishment and wastewater in a unified manner to achieve zero-emission water balance.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a process flow chart of a zero-emission power generation system and method based on open evaporation absorption wastewater purification technology according to an embodiment of the present invention.

Icons: 101-fresh air heater; 102-heat and mass generating tower; 103-heat and mass absorbing tower; 104-wet desulfurization tower; 105-clean water spray tower; 106-boiler; 107-regenerator; 108-circulating sewage heater; 109-evaporator crystallizer; 110-steam turbine; 111-cooler; 112-condenser; 113-air preheater; 114-deoxygenation high-pressure heating system; 115-economizer; 116-low-pressure heater; 117-desalted water heater; 118-flue gas waste heat exchanger.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

As shown in Figure 1, the zero-emission power generation system based on open evaporation absorption wastewater purification technology provided in an embodiment of the present invention includes a fresh air heater 101, a heat and mass generating tower 102, a heat and mass absorption tower 103, a wet desulfurization tower 104, a clean water spray tower 105, a boiler 106, a circulating wastewater heater 108, a regenerator 107, an evaporator crystallizer 109 and a steam turbine 110.

The fresh air heater 101 is used to heat the fresh air entering the system, the heat and mass generating tower 102 is used to generate high-humidity air to enter the heat and mass absorbing tower 103, the liquid water in the sewage is vaporized and discharged with the air, which plays a role in concentrating the sewage, the wet desulfurization tower 104 is used to remove sulfur and other acidic harmful substances in the flue gas generated by the boiler 106, the clean water spray tower 105 is used to cool the exhaust gas of the desulfurization tower and the exhaust gas of the heat and mass absorbing tower 103 and further remove the soluble harmful gases in the flue gas, the boiler 106 is used to burn fuel and heat water into steam, the steam turbine 110 uses the high-temperature steam produced by the boiler 106 to convert thermal energy into mechanical energy to generate electricity for the generator (not shown), the circulating sewage heater 108 is used to heat the circulating sewage of the heat and mass generating tower 102, the regenerator 107 is used to cool the circulating clean water of the heat and mass absorbing tower 103 and heat the circulating sewage of the heat and mass generating tower 102, and the evaporation crystallizer 109 is used to evaporate and crystallize the sewage produced by the system.

The fresh air heater 101 has a fresh air inlet and a fresh air outlet, and the fresh air outlet is connected to the air inlet at the bottom of the heat and mass generating tower 102 and the air inlet of the boiler 106 through a pipeline. The fresh air is preheated by the fresh air heater 101, and is divided into two streams after the temperature rises. One of them is mixed with the exhaust gas at the top of the heat and mass absorbing tower 103, and enters the heat and mass generating tower 102 from the air inlet at the bottom of the heat and mass generating tower 102 to concentrate the sewage. This part accounts for 1% to 3% of the total fresh air flow, and also accounts for 10% to 20% of the total flow entering the bottom of the heat and mass generating tower 102; the other part enters the boiler 106 as the furnace fresh air for combustion, and this part accounts for 97% to 99% of the total fresh air flow.

The air outlet at the top of the heat and mass generating tower 102 is connected to the air inlet at the bottom of the heat and mass absorbing tower 103 through a pipeline, and the air outlet at the top of the heat and mass absorbing tower 103 is connected to the air inlet at the bottom of the heat and mass generating tower 102 through a pipeline. The high-temperature air entering the heat and mass generating tower 102 counter-flows and contacts the sewage sprayed from the top of the heat and mass transfer tower. The high-temperature and high-humidity air is discharged from the top of the heat and mass generating tower 102 and enters the bottom of the heat and mass absorbing tower 103. It counter-flows and contacts the clean water sprayed from top to bottom to reduce the temperature. The water vapor carried is liquefied and stays in the heat and mass absorbing tower 103.

The liquid outlet at the bottom of the heat and mass absorption tower 103 is connected to the liquid inlet at the top of the heat and mass absorption tower 103 through a pipeline passing through the regenerator 107, and the circulating purified water of the heat and mass absorption tower 103 provides a heat source for the regenerator 107. Most of the purified water produced at the bottom of the heat and mass absorption tower 103 (accounting for about 90% to 95% of the purified water extracted from the bottom of the tower) is cooled down through the regenerator 107 and returned to the top of the heat and mass absorption tower 103 to be used as spray water again, and the remaining small part (accounting for about 5% to 10%) is discharged out of the device to maintain the stability of the liquid level at the bottom of the heat and mass absorption tower 103.

The boiler 106 is connected to the steam turbine 110 , and the steam extraction port of the steam turbine 110 is connected to the circulating sewage heater 108 through a pipeline to provide a heat source for the circulating sewage heater 108 .

The circulating sewage heater 108 is arranged on the pipeline connecting the lower liquid outlet and the upper liquid inlet of the heat and mass generating tower 102, and is used to heat the circulating sewage of the heat and mass generating tower 102. The steam extraction port of the steam turbine 110 is connected to the circulating sewage heater 108 through a pipeline, and the steam turbine 110 provides a heat source for the circulating sewage heater 108. The liquid outlet at the lower part of the heat and mass absorbing tower 103 is connected to the liquid inlet at the upper part of the heat and mass absorbing tower 103 through a pipeline passing through the regenerator 107, and the liquid outlet at the lower part of the heat and mass generating tower 102 is connected to the liquid inlet at the upper part of the heat and mass generating tower 102 through a pipeline passing through the regenerator 107. Part of the clean water accumulated at the bottom of the heat and mass absorbing tower 103 is cooled by the regenerator 107 and then refluxed to the top of the heat and mass absorbing tower 103 as a spray liquid, and part of it is discharged from the drainage pipe at the bottom of the tower. The circulating purified water of the heat mass absorption tower 103 provides a heat source for the regenerator 107 , and the circulating sewage of the heat mass generation tower 102 provides a cold source for the regenerator 107 .

Preferably, the power generation system also includes a cooler 111, which is arranged on a pipe between the regenerator 107 and the liquid inlet of the heat mass absorption tower 103. The cooler 111 cools down the circulating clean water cooled by the regenerator 107 again, and uses the circulating clean water cooled by the regenerator 107 as a heat source to heat the cooling water entering the cooler 111, which is then discharged as heating water after being heated.

Under the joint action of the heat and mass generating tower 102 and the heat and mass absorber, the sewage can be purified. Currently, conventional spray towers can be applied to the embodiments of the present invention as the heat and mass generating tower 102 and the heat and mass absorber.

The smoke exhaust port of the boiler 106 is connected to the smoke inlet at the bottom of the wet desulfurization tower 104, the air outlet at the top of the wet desulfurization tower 104 is connected to the air inlet at the bottom of the clean water spray tower 105 through a pipeline, and the air outlet at the top of the heat and mass absorption tower 103 is connected to the air inlet at the bottom of the clean water spray tower 105 through a pipeline.

The flue gas discharged from the combustion of boiler 106 enters the wet desulfurization tower 104 to remove sulfur and other acidic harmful substances in the flue gas generated by boiler 106. After desulfurization, the high-humidity flue gas enters the lower part of the clean water spray tower 105, and is cooled again under the action of clean water spray, and then discharged from the top of the tower; the low-humidity gas discharged from the top of the heat absorption tower 103 also enters the clean water spray tower 105, and is discharged from the top of the tower after cooling again.

The liquid discharge port at the bottom of the clean water spray tower 105 is connected to the liquid inlet at the top of the clean water spray tower 105 and the liquid inlet at the top of the wet desulfurization tower 104 through a pipeline. A part of the spray water generated at the bottom of the clean water spray tower 105 flows back to the top of the clean water spray tower 105 to continue spraying the gas entering the tower, and a part of it enters the wet desulfurization tower 104 as the demister flushing water inside the wet desulfurization tower 104 for desulfurization.

The liquid outlet at the bottom of the wet flue gas desulfurization tower 104 is connected to the liquid inlet at the top of the wet flue gas desulfurization tower 104 and the liquid inlet at the top of the heat and mass generating tower 102 through a pipeline. The liquid outlet at the bottom of the heat and mass generating tower 102 is connected to the liquid inlet at the top of the heat and mass generating tower 102 through a pipeline passing through the regenerator 107 and the circulating sewage heater 108. The circulating sewage of the heat and mass generating tower 102 is heated by the regenerator 107 and the circulating sewage heater 108. The liquid outlet at the bottom of the heat and mass generating tower 102 is connected to the inlet of the evaporation crystallizer 109 through a pipeline. Part of the desulfurization slurry produced at the bottom of the wet desulfurization tower 104 is circulated to the upper part of the wet desulfurization tower 104 to continue to be used as demister flushing water for desulfurization, and part of it is merged with other sewage in the factory and passed into the heat and mass generating tower 102. In the heat and mass generating tower 102, the clean water vapor is carried away by the high-temperature fresh air and enters the heat and mass absorption tower 103; it is discharged from the liquid outlet of the heat and mass generating tower 102 to the evaporator crystallizer 109, and after being processed by the evaporator crystallizer 109, clean water and crystal solid waste are generated.

Preferably, the steam extraction port of the steam turbine 110 is connected to the evaporation crystallizer 109 through a pipeline to provide a heat source for the evaporation crystallizer 109. The heat required by the evaporation crystallizer 109 to perform evaporation crystallization treatment on the incoming sewage is provided by the steam turbine 110.

Preferably, the evaporation crystallizer 109 is also connected to a cooling water inlet pipe and a heating water outlet pipe. The excess heat brought by the steam turbine 110 in the evaporation crystallizer 109 is used to heat the cooling water, which can be discharged as heating water after heating.

Preferably, the boiler 106 includes an air preheater 113 , and the fresh air outlet of the fresh air heater 101 is connected to the air preheater 113 through a pipeline, and the fresh air enters the boiler 106 for combustion after being heated by the air preheater 113 .

Preferably, the boiler 106 also includes a dust collector (not shown), which is connected to the air preheater 113, and the dust collector is connected to the smoke inlet at the bottom of the wet desulfurization tower 104. The flue gas discharged from the boiler 106 is processed by the dust collector and the air preheater 113 in sequence and then enters the wet desulfurization tower 104.

Preferably, the power generation system further includes an economizer 115, which is disposed on a pipeline connecting the air preheater 113 and the wet desulfurization tower 104. The flue gas discharged from the boiler 106 enters the wet desulfurization tower 104 via the dust collector, the air preheater 113 and the economizer 115 in sequence.

Preferably, the power generation system further comprises a deoxygenated high pressure heating system 114, a desalted water heater 117, a low pressure heater 116 and a condenser 112;

The deaerator and high-pressure heater system 114 includes a deaerator and a high-pressure heater;

The deoxygenation high pressure heating system 114 is in communication with the boiler 106;

The exhaust port of the steam turbine 110 is connected to the high-pressure heater and the low-pressure heater 116 through a pipeline, providing a heat source for the high-pressure heater and the low-pressure heater 116;

The condensate outlet of the circulating sewage heater 108 is connected to the deoxygenation high-pressure heating system 114 through a pipeline, and the condensate discharged from the circulating sewage heater 108 enters the deoxygenation high-pressure heating system 114;

The condensed water outlet after the evaporation crystallizer 109 is connected to the deoxygenation high-pressure heating system 114 through a pipeline, and the condensed water discharged from the evaporation crystallizer 109 enters the deoxygenation high-pressure heating system 114;

The condenser 112, the desalted water heater 117, the low-pressure heater 116, the economizer 115 and the deoxygenation high-pressure heating system 114 are connected in sequence; the condenser 112 is connected to the steam turbine 110 through a pipeline, and the exhaust steam of the steam turbine 110 is cooled down into condensed water through the condenser, and the condensed water is heated in sequence by the desalted water heater 117, the low-pressure heater 116 and the economizer 115, and then enters the deoxygenation high-pressure heating system 114; the oxygen contained in the condensed water entering the deoxygenation high-pressure heating system 114 is removed under the action of the deaerator, and then it is heated and pressurized by the high-pressure heater and enters the boiler 106 for vaporization.

It should be noted that the condensed water mentioned above can also be called desalted water.

Optionally, the power generation system further includes a flue gas waste heat exchanger 118, and the pipeline connecting the liquid discharge port at the lower part of the clean water spray tower 105 and the liquid inlet at the upper part of the clean water spray tower 105 passes through the flue gas waste heat exchanger 118;

The flue gas waste heat exchanger 118 is connected to the desalted water heater 117 via an intermediate water circulation pipeline, and the circulating clean water from the clean water spray tower 105 provides a heat source for the desalted water heater 117 through the flue gas waste heat exchanger 118 .

Optionally, the flue gas waste heat exchanger 118 is connected to the fresh air heater 101 via an intermediate water circulation pipeline, and the circulating clean water from the clean water spray tower 105 provides a heat source for the fresh air heater 101 through the flue gas waste heat exchanger 118 .

The process flow of the power generation system and method provided by the embodiment of the present invention is as follows:

①Fresh air process:

After being preheated by the fresh air heater 101, the fresh air absorbs the heat of the intermediate circulating water and is divided into two streams after the temperature is raised. One stream is mixed with the exhaust gas at the top of the heat and mass absorption tower 103 and enters the heat and mass generation tower 102 together to concentrate the sewage; the other stream is heated by the air preheater 113 as the fresh air entering the furnace, and the temperature rises again after absorbing the heat of the flue gas, and enters the boiler 106 for combustion.

②Boiler 106 exhaust process

The exhaust gas from boiler 106 is sequentially subjected to dust removal and denitrification (not shown), air preheater 113, and economizer 115 cooling before entering wet desulfurization tower 104 for desulfurization. Thereafter, it enters clean water spray tower 105 for waste heat recovery. Clean water spraying also has the effect of deep dust removal, and the flue gas after spraying is discharged.

③Air circulation process

The circulating air and the fresh air are mixed and enter the lower part of the heat and mass generating tower 102, and directly exchange heat and mass with the concentrated sewage sprayed down, so that the temperature and moisture content increase, and the sewage is discharged after passing through the demisting device at the top of the heat and mass generating tower 102.

After that, the air enters the lower part of the heat and mass absorption tower 103, and after being sprayed with clean water in a circulating manner, the temperature and moisture content are reduced. The air is defogged by the defogger at the top of the heat and mass absorption tower 103 and then discharged. Most of the air returns to the lower part of the heat and mass generation tower 102 and circulates back and forth. A small amount of air is mixed with the exhaust gas after wet desulfurization through the pipe connected to the exhaust port at the top of the heat and mass absorption tower 103, and enters the clean water spray tower 105 for waste heat recovery.

④Sewage circulation process

The desulfurization wastewater generated by the desulfurization cycle is mixed with other wastewater in the field and enters the wastewater cycle of the heat and mass generating tower 102. The wastewater is directly in contact with the air to achieve a concentration effect. After that, the concentrated wastewater at the bottom of the tower enters the evaporator crystallizer 109 to produce crystalline waste solid.

⑤Intermediate circulating water process

The intermediate circulating water absorbs heat from the flue gas waste heat exchanger 118, and is divided into two streams to go to the fresh air heater 101 and the desalted water heater 117 respectively to heat the fresh air and the desalted water respectively, and then returns to the flue gas waste heat exchanger 118, and the cycle repeats.

⑥Desalted water/steam process

The high-pressure steam generated by the boiler 106 enters the turbine 110 to generate electricity, and is extracted according to its appropriate pressure level, and used as heat sources for the low-pressure heater 116, the deaerator, the high-pressure heater, the heated sewage, and the evaporator crystallizer 109, respectively. The steam condensate cooled by the sewage and the evaporator crystallizer 109 returns to the deaerator.

⑦Heating water/cooling water process

Heating water is used in winter and cooling water is used in summer to cool the clean water circulation and crystallizer.

The embodiment of the present invention further provides a coal-fired power generation method, which is implemented using the power generation system provided by the embodiment of the present invention.

Some parameters of the power generation system and method provided by the present invention in a certain embodiment are as follows:

Boiler 106 volume: rated evaporation capacity 1100t/h;

Boiler 106 exhaust flow rate: 1 million Nm ³ /h;

The outlet of the fresh air heater 101 is used as the fresh air flow rate into the furnace: 600,000 Nm ³ /h;

The outlet of the fresh air heater 101 is used as the fresh air flow rate entering the tower: 15,000 Nm ³ /h;

Fresh air flow rate at the inlet of fresh air heater 101: 615,000 Nm ³ /h;

Fresh air temperature at the inlet of fresh air heater 101: 0℃;

Fresh air temperature at the outlet of fresh air heater 101: 48°C;

The air flow rate discharged from the top of the heat absorption tower 103 is 100,000 Nm ³ /h;

Air flow from the top of the thermal mass absorption tower 103 to the clean water spray tower 105: 15,000 Nm ³ /h;

Air flow from the top of the heat mass absorption tower 103 to the heat mass generation tower 102: 85,000 Nm ³ /h;

Air flow rate into the heat and mass generating tower 102: 100,000 Nm ³ /h (including 15,000 Nm ³ /h of fresh air);

The wastewater replenishment volume of heat and mass generating tower 102: desulfurization wastewater 12t/h, other wastewater in the plant 50t/h, a total of 62t/h;

Thermal mass absorption tower 103 clean water discharge: 60t/h;

Concentrated sewage discharge from heat and mass generating tower 102 (to evaporation crystallizer 109): 2t/h;

Evaporation crystallizer 109 clean water discharge: 1t/h;

Evaporation crystallizer 109 crystal waste solid discharge: 1t/h;

Total steam intake of turbine 110: 1100t/h;

The steam turbine 110 extracts steam to circulate the sewage heater 108 with a flow rate of 19 t/h;

The steam turbine 110 extracts steam to the evaporation crystallizer 109 with a flow rate of 1 t/h;

Steam turbine 110 extraction steam deoxidizer, high pressure heater flow rate: 250t/h;

Flow rate of steam extraction from steam turbine 110 to low-pressure heater 116: 60t/h;

Heat and mass generating tower 102 sewage circulation flow rate: 870t/h;

Thermal mass absorption tower 103 tower clean water circulation flow rate: 870t/h;

Actual inlet flow rate of heat mass absorption tower 103: 810t/h (60t/h discharged as clean water);

Temperature of wastewater entering the heat generating tower 102: 90°C;

Temperature of wastewater at the bottom of heat generating tower 102: 55°C;

The temperature of the purified water entering the heat absorption tower 103 is 45°C;

The temperature of purified water at the bottom of the thermal mass absorption tower 103 is 80°C;

The air temperature at the top of the heat generating tower 102 is 85°C;

The air temperature at the top of the thermal mass absorption tower 103 is 50°C;

Flue gas temperature entering the desulfurization tower: 130℃;

Flue gas temperature out of desulfurization tower: 50℃;

Flue gas temperature out of clean water spray tower 105: 40℃;

Flow rate from steam turbine 110 to condenser 112: 500t/h;

Condenser 112 outlet desalted water flow rate: 770t/h;

Condenser 112 outlet desalted water temperature: 33°C;

The temperature of desalted water after passing through the desalted water heater 117 is 48°C;

The temperature of desalted water after passing through the low-pressure heater 116 and the economizer 115 is 140°C;

The desalted water temperature after passing through the deaerator and high-pressure heater is: 270℃.

The zero-emission power generation system and method based on open evaporation absorption sewage purification technology provided by the embodiment of the present invention have the following characteristics:

1. In the open evaporation absorption sewage purification system, a part of the heated fresh air is blown in, and the generation in the generating tower is more intense due to the lower moisture content of the fresh air. At the same time, a part of the exhaust gas at the top of the heat absorption tower 103 with the lowest temperature in the air circulation (15% in a specific embodiment) is mixed into the flue after desulfurization to maintain the balance of the air circulation gas volume. The heat of this part of the exhaust gas is uniformly recovered together with the exhaust gas after desulfurization, without waste;

2. Solve the problems of desulfurization water replenishment and wastewater in a unified manner to achieve zero-discharge water balance;

3. Recover the heat from the flue gas and sewage concentration process to heat heating water, demineralized water, and fresh air, so as to recycle the heat as much as possible;

4. Organically combine the flue gas circulation, wet desulfurization, desalted water circulation with the sewage circulation and clean water circulation of open evaporation absorption sewage purification technology to achieve comprehensive optimization of thermal, water balance and pollutant balance.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (7)

1. A zero-emission power generation system based on open evaporation absorption sewage purification technology, characterized in that it includes a fresh air heater, a heat and mass generating tower, a heat and mass absorbing tower, a wet desulfurization tower, a clean water spray tower, a boiler, a circulating sewage heater, a regenerator, an evaporation crystallizer and a steam turbine; The fresh air heater has a fresh air inlet and a fresh air outlet, and the fresh air outlet is connected to the air inlet at the bottom of the heat and mass generating tower and the air inlet of the boiler through a pipeline; The air outlet at the top of the heat and mass generating tower is connected to the air inlet at the bottom of the heat and mass absorbing tower through a pipeline, and the air outlet at the top of the heat and mass absorbing tower is connected to the air inlet at the bottom of the heat and mass generating tower through a pipeline; The liquid outlet at the bottom of the heat and mass absorption tower is connected to the liquid inlet at the top of the heat and mass absorption tower through a pipeline passing through the regenerator, and the circulating purified water of the heat and mass absorption tower provides a heat source for the regenerator; The boiler is connected to the steam turbine, and the steam extraction port of the steam turbine is connected to the circulating sewage heater through a pipeline to provide a heat source for the circulating sewage heater; The smoke exhaust port of the boiler is connected to the smoke inlet at the bottom of the wet desulfurization tower, the air outlet at the top of the wet desulfurization tower is connected to the air inlet at the bottom of the clean water spray tower through a pipeline, and the air outlet at the top of the thermal mass absorption tower is connected to the air inlet at the bottom of the clean water spray tower through a pipeline; The liquid discharge port at the bottom of the clean water spray tower is connected to the liquid inlet at the top of the clean water spray tower and the liquid inlet at the top of the wet desulfurization tower through a pipeline, and the liquid outlet at the bottom of the wet desulfurization tower is connected to the liquid inlet at the top of the wet desulfurization tower and the liquid inlet at the top of the heat and mass generating tower through a pipeline; The liquid outlet at the bottom of the heat and mass generating tower is connected to the liquid inlet at the top of the heat and mass generating tower through a pipeline that passes through the regenerator and the circulating sewage heater in sequence, the circulating sewage of the heat and mass generating tower is heated by the regenerator and the circulating sewage heater, and the liquid outlet at the bottom of the heat and mass generating tower is connected to the inlet of the evaporation crystallizer through a pipeline; The steam extraction port of the steam turbine is connected to the evaporation crystallizer through a pipeline to provide a heat source for the evaporation crystallizer; The boiler comprises an air preheater, and the fresh air outlet of the fresh air heater is connected to the air preheater through a pipeline, and the fresh air enters the boiler for combustion after being heated by the air preheater. 2. The power generation system according to claim 1 is characterized in that the boiler includes a dust collector, the dust collector is connected to the air preheater, and the dust collector is connected to the smoke inlet at the bottom of the wet desulfurization tower, and the flue gas discharged from the boiler is processed by the dust collector and the air preheater in sequence and then enters the wet desulfurization tower. 3. The power generation system according to claim 2 is characterized in that the power generation system also includes an economizer, which is arranged on the pipeline connecting the air preheater and the wet desulfurization tower, and the flue gas discharged from the boiler enters the wet desulfurization tower through the dust collector, the air preheater and the economizer in sequence. 4. The power generation system according to claim 3, characterized in that the power generation system further comprises a deoxygenated high-pressure heating system, a desalted water heater, a low-pressure heater and a condenser; The deoxidation and high-pressure heating system comprises a deoxidizer and a high-pressure heater. The deoxygenation high-pressure heating system is in communication with the boiler; The exhaust port of the steam turbine is connected to the high-pressure heater and the low-pressure heater through a pipeline to provide a heat source for the high-pressure heater and the low-pressure heater; The condensate outlet of the circulating sewage heater is connected to the deoxygenation high-pressure heating system through a pipeline, and the condensate discharged from the circulating sewage heater enters the deoxygenation high-pressure heating system; The condensed water outlet after the evaporation crystallizer is connected to the deoxygenation high-pressure heating system through a pipeline, and the condensed water discharged from the evaporation crystallizer enters the deoxygenation high-pressure heating system; The condenser, the desalted water heater, the low-pressure heater, the economizer and the deoxygenation high-pressure heating system are connected in sequence; the condenser is connected to the steam turbine through a pipeline, the exhaust steam of the steam turbine is cooled to condensed water through the condenser, and the condensed water is heated in sequence by the desalted water heater, the low-pressure heater and the economizer and then enters the deoxygenation high-pressure heating system; The condensed water entering the deaeration high-pressure heating system has its oxygen removed by the deaerator, and then enters the boiler for vaporization after being heated and pressurized by the high-pressure heater. 5. The power generation system according to claim 4, characterized in that the power generation system further comprises a flue gas waste heat exchanger, and the pipeline connecting the liquid discharge port at the lower part of the clean water spray tower and the liquid inlet at the upper part of the clean water spray tower passes through the flue gas waste heat exchanger; The flue gas waste heat exchanger is connected to the desalted water heater via an intermediate water circulation pipeline, and the circulating clean water of the clean water spray tower provides a heat source for the desalted water heater through the flue gas waste heat exchanger. 6. The power generation system according to claim 5 is characterized in that the flue gas waste heat exchanger is connected to the fresh air heater through an intermediate water circulation pipeline, and the circulating clean water of the clean water spray tower provides a heat source for the fresh air heater through the flue gas waste heat exchanger. 7. A coal-fired power generation method, characterized in that it is implemented using the power generation system according to any one of claims 1 to 6.