阅读说明：本技术 烟气余热回收用于电厂烟气超净排放和废水零排放的系统 (System for flue gas waste heat recovery is used for power plant's flue gas ultra-clean emission and waste water zero release ) 是由 涂爱民 朱冬生 莫逊 于 2018-05-29 设计创作，主要内容包括：本发明公开了一种烟气余热回收用于电厂烟气超净排放和废水零排放的系统,包括干式电除尘器、低温湿式电除尘器、脱硫塔、喷雾干燥塔、空气烟气换热器、烟气降温换热器、烟气再热器、空气再热器、暖风器、布袋除尘收集装置、烟囱、第一增压风机、第二增压风机和循环泵；空气烟气换热器与烟气降温换热器采用烟气侧串联形式连接于干式电除尘器与低温湿式电除尘器之间；烟气降温换热器通过热媒水输送管和循环泵分别与烟气再热器、暖风器和空气再热器连通。本发明耦合了烟气超净排放和消白烟的废水蒸发零排放系统,采用廉价的余热资源降低废水零排放系统能源成本,提高系统可靠性和稳定性,降低了整体投资及运行费用。(The invention discloses a system for flue gas waste heat recovery and flue gas ultra-clean emission and wastewater zero emission of a power plant, which comprises a dry-type electric dust remover, a low-temperature wet-type electric dust remover, a desulfurizing tower, a spray drying tower, an air flue gas heat exchanger, a flue gas cooling heat exchanger, a flue gas reheater, an air reheater, a fan heater, a cloth bag dust removal collecting device, a chimney, a first booster fan, a second booster fan and a circulating pump, wherein the dry-type electric dust remover is used for removing the flue gas from the; the air flue gas heat exchanger and the flue gas cooling heat exchanger are connected between the dry electric dust remover and the low-temperature wet electric dust remover in a flue gas side series connection mode; the flue gas cooling heat exchanger is respectively communicated with the flue gas reheater, the air heater and the air reheater through a heat medium water delivery pipe and a circulating pump. The invention couples the waste water evaporation zero-discharge system for ultra-clean discharge of smoke and white smoke elimination, adopts cheap waste heat resources to reduce the energy cost of the waste water zero-discharge system, improves the reliability and stability of the system, and reduces the overall investment and the operating cost.)

1. Flue gas waste heat recovery is used for the system of power plant's flue gas ultra-clean emission and waste water zero release, its characterized in that: the device comprises a dry-type electric precipitator, a low-temperature wet-type electric precipitator, a desulfurizing tower, a spray drying tower, an air-flue gas heat exchanger, an intermediate heat medium flue gas/air heat exchanger, a cloth bag dust removal collecting device, a chimney, a first booster fan, a second booster fan and a circulating pump; the intermediate heat medium flue gas/flue gas heat exchanger comprises a flue gas cooling heat exchanger and a flue gas reheater, and the intermediate heat medium flue gas/air heat exchanger comprises an air reheater and a fan heater connected with a second booster fan; the air flue gas heat exchanger and the flue gas cooling heat exchanger are connected between the dry electric dust remover and the low-temperature wet electric dust remover in a flue gas side series connection mode, the first booster fan is arranged between the dry electric dust remover and the air flue gas heat exchanger, and the flue gas reheater is arranged between the desulfurizing tower and the chimney; a dry and hot air inlet of the spray drying tower is connected with the air-flue gas heat exchanger through a flue, a hot and humid air outlet of the spray drying tower is communicated with a gas inlet connecting pipe of the air reheater, and a gas outlet of the air reheater is communicated with an inlet of the bag-type dust removal collecting device; the flue gas cooling heat exchanger is respectively communicated with the flue gas reheater, the air heater and the air reheater through a heat medium water delivery pipe and the circulating pump; the top of the spray drying tower is provided with a high-salinity wastewater sprayer, the bottom of the spray drying tower is connected with a storage bin, and the storage bin is connected with the fluidized drying bed through a pipeline; the lower end of the cloth bag dust removal and collection device is connected to a pipeline between the storage bin and the fluidized drying bed through a pipeline.

2. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1, characterized in that: the spray drying tower is a double-cyclone spray drying tower with a double-cyclone spray type structure; the spray drying tower adopts ambient air as an evaporation carrier; and the ambient air flows in from the top of the spray drying tower in the circumferential direction and is in double-flow rotary atomization with the rotational flow atomization liquid spray of the high-salinity wastewater sprayer in the middle of the top.

3. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 2, characterized in that: the diameter of the double-flow rotary atomized fog drops in the spray drying tower is less than 100 microns, and the high-salinity wastewater sprayer is made of acid-resistant and corrosion-resistant materials.

4. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1, characterized in that: still include flue gas water recovery unit, the upper end of sack dust removal collection device with flue gas water recovery unit links to each other, the upper end of sack dust removal collection device still is connected with the draught fan.

5. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1, characterized in that: the air-gas heat exchanger, the air heater, the air reheater and the gas reheater all adopt high-efficiency heat exchange tubes with high specific surface area.

6. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1, characterized in that: the flue gas cooling heat exchanger is made of an acid corrosion resistant composite pipe or a fluoroplastic pipe.

7. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1 or 5, characterized in that: the air flue gas heat exchanger is made of ND steel materials; the flue gas reheater is made of ND steel material; the air heater and the air reheater are made of 304 stainless steel or 316 stainless steel materials.

8. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 6, characterized in that: the composite pipe is an enamel composite pipe with a high specific surface.

9. The system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission according to claim 1 or 6, characterized in that: and the outlet smoke temperature of the smoke cooling heat exchanger is controlled to be 85-90 ℃.

Technical Field

the invention relates to the technical field of energy conservation and emission reduction of coal-fired power plants, in particular to a system for recycling flue gas waste heat for ultra-clean flue gas emission and zero wastewater emission of a power plant.

Background

With the stricter environmental protection standard of China, the call for implementing the zero discharge of the wastewater of the thermal power plant is increasingly rising in society; meanwhile, no matter a newly built power plant or an in-service power plant which is already put into operation, a hydraulic ash removal system and a wet ash field are not approved in future, so the desulfurization wastewater faces a new potential of being reused everywhere, and a technology for treating the high-concentration salt-containing wastewater at the tail end of the power plant becomes a key to whether the zero discharge of the wastewater of the thermal power plant can be realized. In order to realize zero discharge of waste water of a power plant, a thermal evaporation/evaporation process is the only feasible technical route, and the thermal process needs to consume a large amount of heat energy.

The power plant realizes zero discharge of wastewater, and thermal evaporation/evaporation to dryness is the only feasible technical route, and at present, two technical routes are generally accepted and mainly adopted: (1) flue spraying; (2) a multi-effect evaporation method or an MVR evaporation concentration crystallization method; the latter method is derived from the chemical technology, the high-salinity wastewater is heated by a dividing wall type evaporator, and enters a crystallization separator for solid-liquid separation after being concentrated to supersaturation, the method has the characteristics of higher energy consumption, but the crystallized salt can be recycled as industrial salt; the former method mainly utilizes the low-cost waste heat of the tail flue gas of the boiler at present, and the solid matters after the evaporation of the waste liquid are collected into the soot through a dust remover, and the method has the greatest advantage of low investment and operation cost. The existing evaporative crystallization method has the advantages of relatively mature technology, widest application range, high system reliability, large evaporation energy consumption and high operating cost. The flue spraying method is more and more concerned by the thermal power industry due to the cost advantage, but as the environmental protection standard becomes stricter, whether the method is suitable for disposing the solid matters is controversial in the long run.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a system for flue gas waste heat recovery and power plant flue gas ultra-clean emission and wastewater zero emission, the system recovers low-temperature flue gas waste heat at the tail part of a boiler by using a dividing wall type heat exchange device, is used for eliminating white smoke and spraying high-salinity wastewater at the tail end of a power plant for zero emission, reduces the comprehensive cost of wastewater zero emission treatment, and is coupled with the thermal power plant ultra-clean modification and white smoke elimination technology (the ultra-clean emission low-temperature flue gas reheating system is operated in a combined manner); the problems of white smoke elimination and zero wastewater discharge energy consumption of the power plant are solved by utilizing the waste heat, and the development targets of energy conservation, environmental protection and sustainable development of the power plant are achieved.

The invention is realized by the following technical scheme: the system for recycling the waste heat of the flue gas and realizing the ultra-clean emission of the flue gas and the zero emission of waste water in the power plant comprises a dry-type electric precipitator, a low-temperature wet-type electric precipitator, a desulfurizing tower, a spray drying tower, an air-flue gas heat exchanger, an intermediate heat medium flue gas/air heat exchanger, a cloth bag dust removal and collection device, a chimney, a first booster fan, a second booster fan and a circulating pump; the intermediate heat medium flue gas/flue gas heat exchanger comprises a flue gas cooling heat exchanger and a flue gas reheater, and the intermediate heat medium flue gas/air heat exchanger comprises an air reheater and a fan heater connected with a second booster fan; the air flue gas heat exchanger and the flue gas cooling heat exchanger are connected between the dry electric dust remover and the low-temperature wet electric dust remover in a flue gas side series connection mode, the first booster fan is arranged between the dry electric dust remover and the air flue gas heat exchanger, and the flue gas reheater is arranged between the desulfurizing tower and the chimney; a dry and hot air inlet of the spray drying tower is connected with the air-flue gas heat exchanger through a flue, a hot and humid air outlet of the spray drying tower is communicated with a gas inlet connecting pipe of the air reheater, and a gas outlet of the air reheater is communicated with an inlet of the cloth bag dust removal collecting device; the flue gas cooling heat exchanger is respectively communicated with the flue gas reheater, the air heater and the air reheater through a heat medium water delivery pipe and the circulating pump; the top of the spray drying tower is provided with a high-salinity wastewater sprayer, the bottom of the spray drying tower is connected with a storage bin, and the storage bin is connected with the fluidized drying bed through a pipeline; the lower end of the cloth bag dust removal and collection device is connected to a pipeline between the storage bin and the fluidized drying bed through a pipeline.

Smoke from the tail part of the boiler passes through a dry-type electric dust remover and then an air smoke heat exchanger, the smoke temperature is reduced by about 5 ℃, partial waste heat is released, then the smoke enters a smoke cooling heat exchanger, is continuously cooled to about 90-85 ℃, and then enters a low-temperature wet-type electric dust remover and a desulfurizing tower; the method comprises the following steps that (1) ambient air is heated to about 60 ℃ through a fan heater and then enters an air-flue gas heat exchanger, the temperature is raised to 105-110 ℃ after the air-flue gas heat exchanger absorbs waste heat, then the ambient air enters a spray drying tower to evaporate waste water, and hot air absorbing the waste water is discharged on site or is converged into a flue gas water recovery device behind a desulfurization tower; most of solid matters in the wastewater enter a storage bin at the bottom of the spray drying tower for collection, a small part of the solid matters are collected by a cloth bag dust removal and collection device, and the collected solid matters are transported outside or recycled; the hot medium water enters a flue gas cooling heat exchanger to absorb the waste heat of the flue gas, the temperature is raised to about 85-90 ℃, and then the hot medium water is divided into three streams, most of the hot medium water enters a flue gas reheater at the outlet of a desulfurization tower, and a small part of the hot medium water enters a fan heater in front of the flue gas cooling heat exchanger and an air reheater at the outlet of a spray drying tower, and the hot medium water returns to the flue gas cooling heat exchanger after; this device combines together waste water zero release technique and power plant's flue gas ultra-clean emission and flue gas white technique that disappears, and based on the requirement that flue gas ultra-clean emission needs lower flue gas temperature, through retrieving low temperature flue gas waste heat and be used for discharging fume and again heat white and high salt waste water spray evaporation, compromise the environmental protection requirement of discharging fume and waste water zero release simultaneously.

The spray drying tower is a double-cyclone spray drying tower with a double-cyclone spray type structure; the spray drying tower adopts ambient air as an evaporation carrier; and ambient air flows in from the top of the spray drying tower in the circumferential direction and is in double-flow rotary atomization with the rotational flow atomization liquid spray of the high-salinity wastewater sprayer in the middle of the top. The spray drying tower adopts the ambient air as an evaporation carrier, so that negative effects on safe operation of wet electric dust removal and resource utilization of smoke dust caused by direct use of flue gas evaporation and mixing of solid particles in the wastewater into the smoke dust are avoided.

The diameter of the double-flow rotary atomized fog drops in the spray drying tower is less than 100 microns, and the high-salt waste water sprayer is a sprayer made of acid-resistant and corrosion-resistant materials.

Still include flue gas water recovery unit, the upper end of sack dust removal collection device with flue gas water recovery unit links to each other, the upper end of sack dust removal collection device still is connected with the draught fan.

The air-gas heat exchanger, the air heater, the air reheater and the gas reheater all adopt high-efficiency heat exchange tubes with high specific surface area. The high-efficiency heat exchange tube with a high specific surface is adopted, so that the weight and the cost of the heat exchanger are favorably reduced, and the volume of the heat exchanger is reduced.

The flue gas cooling heat exchanger is made of an acid corrosion resistant composite pipe or a fluoroplastic pipe.

The air flue gas heat exchanger is made of ND steel materials; the flue gas reheater is made of ND steel material; the air heater and the air reheater are made of 304 stainless steel or 316 stainless steel materials. The air-smoke heat exchanger is made of ND steel materials, and measures such as near-dew-point wall temperature control, air variable flow strategies and the like are adopted to ensure that the temperature control of the smoke side is higher than the acid dew-point temperature; the material of 304 stainless steel or 316 stainless steel is adopted, so that the investment and the volume can be reduced.

The composite pipe is an enamel composite pipe with a high specific surface. Because most of the heat exchange sections of the flue gas cooling heat exchanger are below an acid dew point, the flue gas cooling heat exchanger is made of an enamel composite pipe material with a high specific surface.

And the outlet smoke temperature of the smoke cooling heat exchanger is controlled to be 85-90 ℃.

Compared with the prior art, the invention has the advantages that: the system has lower initial investment and operation cost, more flexible selection of the wastewater pretreatment process, higher system reliability and shorter construction period; compared with flue spray evaporation, although the initial investment cost is increased, the system reliability and the environmental protection level are higher, the sustainable development requirement is better met, and the wet electric dust removal system cannot be adversely affected; on the premise of not influencing the reheating and white smoke elimination of the flue gas after the ultra-clean transformation of the power plant, the requirements of low cost and high reliability for treating the zero emission of the high-salinity wastewater of the power plant are met.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

The reference numerals in the drawings mean: 1. a dry electric precipitator; 2. an air-flue gas heat exchanger; 3. a flue gas cooling heat exchanger; 4. a flue gas reheater; 5. a low-temperature wet electric dust collector; 6. a desulfurizing tower; 7. a spray drying tower; 8. a bag-type dust collection device; 9. a chimney; 10. a first booster fan; 11. a second booster fan; 12. A circulation pump; 13. storing in a warehouse; 14. a warm air blower; 15. an air reheater; A. from boiler flue gases; b. Air; C. high salt waste water; D. feeding the solid matter to a fluidized drying bed; E. and (4) diffusing or returning to the flue gas water recovery device.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and detailed description.