Waste heat recovery system for inlet air of desulfurization slurry flash evaporation long-conveying heating boiler

Abstract

The utility model relates to a waste heat recovery system for heating inlet air of a boiler through flash evaporation and long conveying of desulfurization slurry, and belongs to the technical field of waste heat utilization. Steam exhaust generated by a first flash evaporation unit provides a heat source for a first heat exchange unit through a long conveying pipeline, and a pressurizing unit for pressurizing the steam exhaust is arranged on the long conveying pipeline; the first heat exchange unit is provided with a first fresh air inlet and a first heating air outlet. Gas-liquid separation is carried out on the desulfurization slurry in the mode that the negative pressure environment is artificially manufactured, extracted heat leaves the slurry flash evaporation unit in the form of steam, waste heat recovery of the desulfurization slurry is achieved, primary preheating of primary inlet air and secondary inlet air of the boiler is achieved by arranging the first heat exchange unit and the second heat exchange unit, and waste heat recovery of the desulfurization slurry is achieved. An electric heating device in an original boiler air inlet system is replaced, use of energy is reduced, meanwhile, part of clean condensate water generated due to steam condensation can be recycled, double benefits of hot water and water are achieved, and the utilization and recovery rate of the system is increased.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of waste heat utilization, especially relates to a waste heat recovery system of desulfurization slurry flash evaporation long conveying heating boiler air inlet. BACKGROUND

[0002] In the desulfurization process of power plant, desulfurization slurry is the key to purify flue gas. It can absorb sulfur dioxide and other acid gases in flue gas, so that pollution emission is reduced. The heat of desulfurization slurry mainly comes from the following two aspects: on the one hand, when desulfurizing, sulfur dioxide reacts with alkaline substances to generate calcium sulfite, calcium sulfate and other substances, which will release a large amount of heat. On the other hand, the mechanical energy generated by the operation of slurry circulating pump and other equipment will also be converted into heat energy and transferred to the slurry, so that the temperature of desulfurization slurry is increased. Relevant data shows that the temperature of desulfurization slurry is stabilized at 45-65℃, which belongs to medium and low temperature waste heat. Although this part of waste heat cannot be directly used for power generation, it can be used for regional heating to provide heat for residents and commercial buildings; it can also prepare domestic hot water to reduce heating energy consumption; it can also preheat the air inlet of the boiler to improve the combustion efficiency. If this part of waste heat can be reasonably utilized, energy cascade utilization can be realized, and energy comprehensive utilization efficiency can be improved.

[0003] At present, some power plants have fully realized the value of desulfurization slurry waste heat resources and put it into practice. For example, some power plants use heat exchangers to transfer the heat of desulfurization slurry to circulating water, and the heated circulating water can be used for heating or supplying domestic hot water; some power plants use this part of waste heat to preheat the air entering the boiler, which not only improves the thermal efficiency of the boiler, but also reduces fuel consumption. However, a considerable number of power plants have not effectively developed this part of waste heat resources, and there is still a large space for waste heat exploitation. If reasonable technical means and carefully designed utilization system can be used, energy can be used efficiently, and the operation cost and energy consumption of power plant can be reduced.

[0004] At present, the following energy utilization directions can be optimized in power plant: on the one hand, some power plants use electric air heaters to preheat the air inlet of the boiler. The working principle is that electric heating elements such as resistance wire and PTC ceramic heating element convert electric energy into heat energy. When cold air flows through the electric air heater, it exchanges heat with the heating element to increase the temperature of the air. However, this method consumes a large amount of electricity during use, which greatly increases the operation cost of the system. On the other hand, the land resources in power plant are relatively scarce at present, so the newly added equipment often faces the problem of long distance from the target equipment and difficult steam transportation, which limits the selection of equipment. UTILITY MODEL CONTENTS

[0005] The utility model provides a kind of desulfurization slurry flash evaporation long conveying heating boiler air intake's waste heat recovery system, comprising: first flash evaporation unit, the steam exhaust generated by the first flash evaporation unit provides heat source for first heat exchange unit by long conveying pipeline, the long conveying pipeline is provided with the booster unit for pressurizing steam exhaust, first fresh air inlet and first heating air outlet are provided on the first heat exchange unit.

[0006] Further, it further includes second heat exchange unit, the steam exhaust generated by the first flash evaporation unit provides heat source for second heat exchange unit by long conveying pipeline, second fresh air inlet and second heating air outlet are provided on the second heat exchange unit.

[0007] Further, the first heating air outlet and second heating air outlet are connected with the first air medium inlet and the second air medium inlet of the rotary air preheater respectively.

[0008] Further, the first heating air outlet is connected with the first air medium inlet or / and the second air medium inlet of the rotary air preheater.

[0009] Further, the long conveying pipeline is provided with third heat exchange unit for reheat gas in the long conveying pipeline.

[0010] Further, the first heat exchange unit, second heat exchange unit and third heat exchange unit are all finned heat exchanger.

[0011] Further, the long conveying pipeline is provided with liquid discharge valve for discharging condensate.

[0012] Further, the first heat exchange unit and second heat exchange unit are both provided with condensate drainage pipeline, and the condensate drainage pipeline is provided with water return pump.

[0013] Further, the long conveying pipeline is arranged obliquely.

[0014] Further, the heat source medium of the first flash evaporation unit is desulfurization slurry.

[0015] The utility model has the advantages that:

[0016] 1. The desulfurization slurry is separated by artificially creating negative pressure environment, and the extracted heat is in the form of steam leaving the slurry flash evaporation unit, realizing waste heat recovery of desulfurization slurry.

[0017] 2. The booster unit is arranged to solve the problem of short transportation distance caused by insufficient pressure difference of flash evaporation exhaust, and effectively realize long-distance transportation of steam.

[0018] 3. By setting the first heat exchange unit and the second heat exchange unit, primary preheating of the boiler primary air inlet and the boiler secondary air inlet is realized, the electric warm air device in the original boiler air inlet system is replaced, energy use is reduced, and part of clean condensate water generated due to steam condensation can be recovered, heat and water double benefits are realized, and the utilization recovery rate of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the system diagram of the embodiment 1 of the utility model, and

[0020] Figure 2 is the system diagram of the embodiment 2 of the utility model.

[0021] The figure sign, first flash evaporation unit 100, long conveying pipeline 200, first heat exchange unit 300, first fresh air inlet 310, first heated air outlet 320, booster unit 400, second heat exchange unit 500, second fresh air inlet 510, second heated air outlet 520, rotary air preheater 600, third heat exchange unit 700, condensate water drainage pipeline 800, backwater pump 900, liquid discharge valve 1000. DETAILED DESCRIPTION

[0022] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the utility model, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0023] In the description of the utility model, it should be explained that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood through specific circumstances.

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0025] Example 1: As Figure 1 As shown, a waste heat recovery system for heating boiler intake air via flash evaporation of desulfurization slurry includes: a first flash evaporation unit 100, wherein the exhaust steam generated by the first flash evaporation unit 100 provides a heat source for a first heat exchange unit 300 via a long conveying pipeline 200; a pressurization unit 400 for pressurizing the exhaust steam is installed on the long conveying pipeline 200; and a first fresh air inlet 310 and a first heated air outlet 320 are installed on the first heat exchange unit 300. The first heated air outlet 320 is connected to a first air medium inlet and / or a second air medium inlet of a rotary air preheater 600. A third heat exchange unit 700 for supplementing the heating of the gas within the long conveying pipeline 200 is installed on the long conveying pipeline 200. Both the first heat exchange unit 300 and the third heat exchange unit 700 are finned heat exchangers. A drain valve 1000 for discharging condensate is installed on the long conveying pipeline 200. Both the first heat exchange unit 300 and the second heat exchange unit 500 are equipped with condensate drain pipes 800, and each condensate drain pipe 800 is equipped with a return water pump 900. The long conveying pipe 200 is arranged at an angle. The heat source medium of the first flash evaporation unit 100 is desulfurization slurry.

[0026] The first flash unit 100 separates gas and liquid phases by flashing the desulfurization slurry in a negative pressure environment, extracting medium and low temperature waste heat. The waste heat of the desulfurization slurry is recovered, and the heat of 45-65°C is converted into steam exhaust to reduce energy waste. The gas-liquid separation is completed by pressure change only, reducing system energy consumption. The long conveying pipeline 200 transports the steam exhaust to the heat exchange unit, supporting ultra-long distance transportation of ≥200m. The problem of long distance between equipment layout in power plants is solved, and the site restrictions are flexibly adapted. The inclined arrangement of the pipeline is designed to cooperate with the drain valve 1000 to effectively drain the condensed water. The condensed water in the long conveying pipeline 200 is drained regularly to prevent excessive accumulation of condensed water in the pipeline, thereby reducing the heat loss of steam during transportation. The booster unit 400, which can be a booster fan, pressurizes the steam exhaust to increase the transportation pressure and overcome the resistance of long distance transportation. The steam exhaust maintains sufficient pressure during long distance transportation to avoid condensation or interruption of transportation caused by insufficient pressure. In cooperation with the insulation layer design, the heat loss during transportation is reduced. The first heat exchange unit 300 transfers the heat of the steam exhaust to the boiler inlet air through the finned heat exchanger. The boiler inlet air is preheated to improve combustion efficiency, replace traditional electric air heaters, and reduce high-grade electric energy consumption. The fin structure increases the heat exchange area and enhances the heat transfer efficiency, shortening the preheating time. The third heat exchange unit 700 supplements heat on the long conveying pipeline to compensate for heat loss during transportation. The steam temperature is maintained to reduce condensation and extend the effective transportation distance. The heat exchange unit inlet steam still has sufficient latent heat to improve the overall system energy efficiency. The condensate drainage pipeline 800 and the drain pump 900 collect and drain the condensed water generated by the heat exchange unit to maintain system pressure balance. The recovered clean condensed water realizes "heat-water double benefits" and improves water resource utilization. The drain pump ensures that the condensed water is drained in time to avoid affecting the heat exchange efficiency. The rotary air preheater 600 receives the heated air to further preheat the boiler inlet air. The boiler combustion process is optimized to improve overall thermal efficiency and reduce fuel consumption. The heat exchange unit works together to form a multi-stage preheating system to enhance energy saving effect.

[0027] Example 2: as Figure 2As shown, a waste heat recovery system for flash evaporation of desulfurization slurry and long-distance heating of boiler inlet air, comprising: a first flash evaporation unit 100, steam waste gas generated by the first flash evaporation unit 100 provides heat source for a first heat exchange unit 300 through a long-distance pipeline 200, a booster unit 400 is arranged on the long-distance pipeline 200 for pressurizing the steam waste gas, and a first fresh air inlet 310 and a first heated air outlet 320 are arranged on the first heat exchange unit 300. A second heat exchange unit 500 is further included, and the steam waste gas generated by the first flash evaporation unit 100 provides heat source for the second heat exchange unit 500 through the long-distance pipeline 200, and a second fresh air inlet 510 and a second heated air outlet 520 are arranged on the second heat exchange unit 500. The first heated air outlet 320 and the second heated air outlet 520 are respectively connected with a first air medium inlet and a second air medium inlet of a rotary air preheater 600. The first heated air outlet 320 is connected with the first air medium inlet and / or the second air medium inlet of the rotary air preheater 600. A third heat exchange unit 700 is arranged on the long-distance pipeline 200 for supplementing heat to the gas in the long-distance pipeline 200. The first heat exchange unit 300, the second heat exchange unit 500 and the third heat exchange unit 700 are all finned heat exchangers. A drain valve 1000 is arranged on the long-distance pipeline 200 for discharging condensed water. Condensed water drain pipes 800 are arranged on the first heat exchange unit 300 and the second heat exchange unit 500, and water return pumps 900 are arranged on the condensed water drain pipes 800. The long-distance pipeline 200 is arranged obliquely. The heat source medium of the first flash evaporation unit 100 is desulfurization slurry.

[0028] Compared with Example 1, the second heat exchange unit 500 is added in this embodiment to realize independent preheating of secondary boiler inlet air, and a hierarchical heating system is formed with the first heat exchange unit 300, so as to optimize the boiler combustion air distribution and improve the overall thermal efficiency.

[0029] Working process:

[0030] Desulfurization slurry flash evaporation stage: desulfurization slurry at 65℃ enters the first flash evaporation unit 100 through a slurry inlet, and steam waste gas at 60℃ is generated by flash evaporation under negative pressure. The unevaporated slurry returns to the desulfurization system through a drain port and continues to participate in the circulation.

[0031] Steam pressurization and long-distance transportation: after being pressurized by the booster unit 400, the steam waste gas is transported to the remote heat exchange unit through the long-distance pipeline 200. The third heat exchange unit 700 supplements heat to the steam in the pipeline to maintain stable temperature and reduce condensation.

[0032] The boiler air inlet is heated in stages: primary air inlet heating: fresh air enters the first heat exchange unit 300 through the first fresh air inlet 310, and after heat exchange with steam, enters the air preheater 600 through the first heated air outlet 320. Secondary air inlet heating: another path of fresh air enters the second heat exchange unit 500 through the second air inlet 510, and after heating, enters the air preheater 600 through the second heated air outlet 520.

[0033] Condensate recovery and system maintenance: The condensate produced by the heat exchange unit is discharged through the drain pipe 800 and the drain pump 900 for recycling. The long conveying pipeline 200 is arranged obliquely, and the drain valve 1000 periodically discharges the condensate in the pipeline to ensure smooth conveying.

[0034] The above describes the embodiments of the present application in detail, but the content is only the preferred embodiment of the present application, and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made within the scope of the present application should still belong to the patent coverage of the present application.

Claims

1. A desulfurized slurry flash vaporization long-conveying heating boiler intake air waste heat recovery system, characterized by, The application relates to a heat exchange system for a long-distance pipeline. The first flash unit (100) generates steam waste gas which provides heat source for the first heat exchange unit (300) through a long-distance pipeline (200) provided with a booster unit (400) for pressurizing the steam waste gas, and the first heat exchange unit (300) is provided with a first fresh air inlet (310) and a first heated air outlet (320).

2. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 1, characterized in that, The first flash unit (100) generates steam waste gas which provides heat source for the second heat exchange unit (500) through the long-distance pipeline (200), and the second heat exchange unit (500) is provided with a second fresh air inlet (510) and a second heated air outlet (520).

3. A waste heat recovery system for flash vaporization of a desulfurized slurry and long distance transportation of the boiler intake air according to claim 2, characterized in that, The first heated air outlet (320) and the second heated air outlet (520) are respectively connected with a first air medium inlet and a second air medium inlet of a rotary air preheater (600).

4. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 1, characterized in that, The first heated air outlet (320) is connected with the first air medium inlet and / or the second air medium inlet of the rotary air preheater (600).

5. The waste heat recovery system of claim 1 or 2, wherein the waste heat recovery system is a waste heat recovery system for desulfurized slurry flash vaporization long distance transportation heating boiler intake air, characterized in that, The long-distance pipeline (200) is provided with a third heat exchange unit (700) for supplementing heat to the gas in the long-distance pipeline (200).

6. A waste heat recovery system for flash vaporization of a desulfurized slurry and long distance transportation of the boiler intake air according to claim 5, characterized in that, The first heat exchange unit (300), the second heat exchange unit (500) and the third heat exchange unit (700) are all finned heat exchangers.

7. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 1, characterized in that, The long-distance pipeline (200) is provided with a liquid discharge valve (1000) for discharging condensed water.

8. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 2, characterized in that, The first heat exchange unit (300) and the second heat exchange unit (500) are both provided with a condensed water drainage pipeline (800) provided with a water return pump (900).

9. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 1, characterized in that, The long-distance pipeline (200) is arranged in an inclined mode.

10. A waste heat recovery system for flash vaporization of desulfurized slurry and long distance transportation of the boiler intake air according to claim 4, characterized in that, The heat source medium of the first flash unit (100) is desulfurization slurry.

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