Waste incineration flue gas waste heat utilization system and flue gas waste heat absorption tower

Abstract

The invention discloses a waste incineration flue gas waste heat utilization system and a flue gas waste heat absorption tower, and relates to the field of waste incineration flue gas purification and flue gas waste heat recycling. To-be-treated flue gas is treated through a flue gas pretreatment subsystem in advance, and by adjusting the spraying flow, the condensate amount of the flue gas in a pretreatment section is reduced, and the sewage generation amount is reduced; therefore, the sewage treatment cost is reduced. Afterwards, the mode of controlling the state parameters of the spraying water in the spraying device is adopted, most of the to-be-treated flue gas heat is recycled, and the flue gas heat recycling efficiency is improved. And finally, the obtained saturated wet flue gas is input into the flue gas reheating subsystem, and the problem of flue corrosion is solved by arranging the flue gas reheating subsystem with a heat exchange adjusting function, particularly arranging a flue gas heat exchanger and a flue gas bypass channel to improve the superheat degree of the flue gas at the outlet of the absorption tower.

Description

Technical Field

[0001] The present application relates to the technical field of waste incineration flue gas purification and flue gas waste heat recovery and utilization, and in particular to a waste incineration flue gas waste heat utilization system and a flue gas waste heat absorption tower. Background Art

[0002] The heat loss from flue gas emissions in waste incineration power plants is an important component of the heat loss of the entire plant.

[0003] The known technology uses a five-step method of "SNCR (Selective Non-Catalytic Reduction) + semi-dry method + dry method + activated carbon + bag dust removal" to treat flue gas. The temperature of the flue gas discharged after the flue gas treatment is 130°~150°. Direct discharge will cause a large amount of heat loss.

[0004] In order to recover the heat in the exhaust flue gas, in the known technology, a flue gas-water heat exchanger is connected to the tail of the flue gas exhaust duct, and the cold source water in the flue gas-water heat exchanger directly exchanges heat with the flue gas to be discharged. However, this heat recovery method has low efficiency. Summary of the invention

[0005] In view of the above problems, the present application provides a waste incineration flue gas waste heat utilization system to achieve the purpose of recovering the heat in the pre-discharged flue gas. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a waste incineration flue gas waste heat utilization system, comprising a waste heat recovery subsystem, a flue gas reheating subsystem, and a flue gas pretreatment subsystem connected to the waste heat recovery subsystem;

[0007] After being discharged from the exhaust fan outlet, the flue gas to be treated is processed in sequence by the flue gas pretreatment subsystem, the waste heat recovery subsystem and the flue gas reheating subsystem;

[0008] Among them, the flue gas pretreatment subsystem includes a flue gas scrubber, a circulating water pump, a water supply pump and a pretreatment circulating water tank;

[0009] The flue gas to be treated enters the flue gas pretreatment subsystem through the flue; the flue gas scrubber obtains the scrubbing solution from the pretreatment circulating water tank through the circulating water pump, and uses the scrubbing solution to spray the flue gas to be treated, thereby obtaining scrubbing wastewater containing acidic pollutants and particulate matter and clean wet flue gas; the flue gas pretreatment subsystem transports the clean wet flue gas to the waste heat recovery subsystem through the flue;

[0010] The make-up water pump is connected to the pretreatment circulating water tank and the waste heat recovery subsystem respectively, and is used to obtain the make-up water required by the pretreatment circulating water tank from the waste heat recovery subsystem;

[0011] The sewage pump is connected to the pretreatment circulating water tank and the wastewater treatment subsystem respectively, and is used to regularly discharge the tobacco washing wastewater in the pretreatment circulating water tank to the wastewater treatment subsystem.

[0012] In a possible implementation, the waste heat recovery subsystem includes a spray heat exchange section with a preset level;

[0013] The preset level of spray heat exchange sections includes at least a primary spray heat exchange section and a secondary spray heat exchange section, each section is provided with a spray device, and the spray water state parameters of the spray device are set according to the state of the initial flue gas input into each spray heat exchange section; the spray device controls the temperature drop amplitude of the flue gas by controlling the state parameters of the spray water in the spray heat exchange section, so that the flue gas to be treated is sprayed and heat exchanged through the primary spray heat exchange section and the secondary spray heat exchange section in turn to obtain saturated wet flue gas; the heat exchanger in the waste heat recovery subsystem obtains flue gas heat from the spray water obtained after spraying the spray heat exchange section.

[0014] In a possible implementation, the flue gas heat exchanger in the flue gas reheating subsystem is arranged in the flue;

[0015] A flue gas flow regulating valve is provided in the flue gas reheating subsystem, and the flue gas flow regulating valve is respectively connected to the heating discharge channel and the flue gas bypass channel, and is used to control the flow of saturated wet flue gas flowing into the heating discharge channel and the flue gas bypass channel; the heating discharge channel introduces the saturated wet flue gas into the flue gas heat exchanger, and the flue gas heat exchanger collects the heat of the flue gas to be treated flowing through the flue, and uses the heat to heat the incoming saturated wet flue gas and then discharges it; the flue gas bypass channel is used to directly discharge the incoming saturated wet flue gas.

[0016] In one possible implementation, when the load of the waste incineration power plant where the waste incineration flue gas waste heat utilization system is located is lower than a preset threshold, the flue gas reheating subsystem will mix and discharge the superheated flue gas obtained by heating the saturated wet flue gas through the flue gas heat exchanger with the saturated wet flue gas directly discharged through the flue gas bypass channel.

[0017] In one possible implementation, the waste heat recovery subsystem also includes a waste heat recovery spray water tank and a water volume control device;

[0018] The waste heat recovery spray water tank is connected to the spray device to provide spray water for the spray device;

[0019] The water volume control device is installed on the waste heat recovery spray water tank; the water volume control device detects whether the circulating water volume in the waste heat recovery spray water tank exceeds the preset standard volume according to the preset cycle. When it is detected that the circulating water volume exceeds the preset standard volume, the drainage device of the waste heat recovery spray water tank is controlled to discharge the circulating water exceeding the preset standard volume.

[0020] In a possible implementation, the primary spray water collection tank in the waste heat recovery subsystem is connected to the pretreatment circulating water tank;

[0021] When the liquid level detection device in the pretreatment circulating water tank detects that the liquid level in the pretreatment circulating water tank reaches the water replenishment level, a water replenishment prompt signal is generated and sent to the primary spray water tank;

[0022] After receiving the water replenishment prompt signal, the first-stage spray water tank inputs the first-stage spray water into the pretreatment circulation water tank.

[0023] In a possible implementation, it also includes a wastewater treatment subsystem connected to the flue gas pretreatment subsystem;

[0024] The wastewater treatment system is used to treat the flue gas washing wastewater and polluted sediments generated after washing the flue gas to be treated in the pretreatment circulating water tank according to a preset cycle.

[0025] In a possible implementation, it also includes a heating section connected to the waste heat recovery subsystem;

[0026] The heating section includes the heating network water system;

[0027] The hot network water system is connected to the heat exchanger; the hot network water in the hot network water system absorbs the flue gas heat recovered in the heat exchanger.

[0028] In a possible implementation, the heat network water system further includes a temperature detection device and a steam supplementary heater;

[0029] When the temperature detection device detects that the temperature of the hot network water that absorbs the heat of the flue gas does not reach the preset heating temperature, a steam supplementary heater is used to heat the hot network water that absorbs the heat of the flue gas to the preset heating temperature.

[0030] In a possible implementation, it also includes a steam turbine condensate heat exchanger connected to the flue gas pretreatment subsystem;

[0031] After being discharged from the exhaust fan outlet, the flue gas to be treated first passes through the turbine condensate heat exchanger. The turbine condensate heat exchanger obtains heat from the flue gas to be treated and then heats the turbine condensate in the turbine condensate heat exchanger.

[0032] In one possible implementation, the waste incineration flue gas waste heat utilization system operates throughout the year, the heat network water system operates during the heating season, and the steam turbine condensate heat exchanger operates during the heating season.

[0033] Also included is a steam turbine connected to the heat exchanger;

[0034] The steam turbine obtains the flue gas heat from the heat exchanger and heats the condensate in the steam turbine.

[0035] A second aspect of the present application provides a flue gas waste heat absorption tower, comprising a tower body, and also comprising a waste incineration flue gas waste heat utilization system as described in any one of the above items;

[0036] The tower body comprises a first flue section and a second flue section connected in sequence;

[0037] The flue gas pretreatment subsystem and the flue gas reheating subsystem are arranged in the first flue section, and the waste heat recovery subsystem is arranged in the second flue section.

[0038] By means of the above technical scheme, the waste incineration flue gas waste heat utilization system and flue gas waste heat absorption tower provided by the present application are as follows: before the flue gas to be treated enters the waste heat recovery subsystem, the flue gas is pre-treated by the flue gas pretreatment subsystem, and the condensation amount of the flue gas in the pretreatment section is reduced by adjusting the spray flow rate, and the amount of sewage generated is reduced, thereby reducing the cost of sewage treatment. Afterwards, the flue gas to be treated is sprayed and heat exchanged with the pre-set level of spray heat exchange sections in the waste heat recovery subsystem. Each spray heat exchange section is provided with a spray device. The spray device in each spray heat exchange section sets the state parameters of the spray water according to the state of the initial flue gas input into the section. The temperature drop of the flue gas is controlled by controlling the state parameters of the spray water, so that the flue gas to be treated is sprayed and heat exchanged in turn through the first spray heat exchange section and the second spray heat exchange section. The present application adopts the method of controlling the state parameters of the spray water in the spray device to recover most of the heat of the flue gas to be treated, thereby improving the efficiency of flue gas heat recovery. Finally, the obtained saturated wet flue gas is input into the flue gas reheating subsystem. By setting up a flue gas reheating subsystem with a heat exchange regulation function, specifically by setting up a flue gas heat exchanger and a flue gas bypass channel, the superheat of the flue gas at the outlet of the absorption tower is increased, thereby solving the problem of flue corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0040] Figure 1 A schematic diagram of the system composition structure of a waste incineration flue gas waste heat utilization system provided in this application;

[0041] Figure 2 This is an example diagram of the system composition structure of the waste incineration flue gas waste heat utilization system provided in this application. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0043] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0044] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, which is only to describe the distinction mode adopted by the objects of the same attributes when describing in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0045] The known technology adopts a five-step method to treat the flue gas generated by garbage incineration. The temperature of the treated flue gas is 130°~150°, and the moisture content is 20%~30%. Direct discharge will cause a large amount of heat loss and pollute the environment.

[0046] In the known technology, a flue gas-water heat exchanger is directly connected to the tail end of the flue gas discharge duct, and the cold source water in the flue gas-water heat exchanger directly exchanges heat with the flue gas to be discharged. This flue gas waste heat recovery method has low heat recovery efficiency, cannot recover water resources in the flue gas to be discharged, and cannot further purify the flue gas to be discharged.

[0047] In order to solve the above problems, the present application provides a waste incineration flue gas waste heat utilization system.

[0048] See also Figure 1 , a schematic diagram of the system composition structure of the waste incineration flue gas waste heat utilization system provided in this application.

[0049] like Figure 1 As shown, the waste incineration flue gas waste heat utilization system provided in this application mainly includes a flue gas pretreatment subsystem, a waste heat recovery subsystem and a flue gas reheating subsystem.

[0050] After the flue gas to be treated is discharged from the outlet of the induced draft fan, it first enters the flue gas pretreatment subsystem for pretreatment to obtain clean wet flue gas, then the clean wet flue gas enters the waste heat recovery subsystem for treatment to obtain saturated wet flue gas, and finally the saturated wet flue gas is treated by the flue gas reheating subsystem and discharged. Next, the various subsystems in the waste incineration flue gas waste heat utilization system are processed in turn according to the above processing order for the flue gas to be treated.

[0051] First, let’s introduce the flue gas pretreatment subsystem:

[0052] The flue gas pretreatment subsystem can be understood as a flue gas washing system, including a flue gas washing device, a circulating water pump, a make-up water pump, a sewage pump and a pretreatment circulating water tank.

[0053] Among them, the flue gas scrubbing device can be an atomizing spray device, and the atomizing spray device can specifically include an atomizing nozzle.

[0054] The pretreatment circulating water tank stores the washing solution. The atomizing spray device obtains the washing solution from the pretreatment circulating water tank through the circulating water pump and sprays the flue gas to be treated with the washing solution. The washing solution is an alkaline solution with a relatively high temperature. Therefore, after passing through the flue gas pretreatment subsystem, the particulate matter and acidic pollutants in the flue gas to be treated will enter the pretreatment circulating water tank along with the washing solution. It should be noted that due to the high temperature of the sprayed washing solution, the temperature of the clean wet flue gas output from the flue gas pretreatment subsystem will not be much lower than the temperature of the input flue gas to be treated. During the spray washing process, the flue gas to be treated transfers the sensible heat of the flue gas to the sprayed washing solution, and the temperature of the flue gas to be treated is reduced. Correspondingly, the sprayed washing solution will absorb heat and evaporate, and finally the clean wet flue gas is output from the flue gas pretreatment subsystem.

[0055] The main function of the flue gas pretreatment subsystem is to wash out pollutants such as particulate matter and acidic pollutants in the flue gas to be treated, obtain flue gas with higher cleanliness, and then input it into the waste heat recovery subsystem. It can be seen that the flue gas pretreatment subsystem can reduce the concentration of acidic pollutants and particulate matter in the flue gas to be treated, increase the humidity of the flue gas to be treated, and reduce the temperature of the flue gas to be treated, thereby obtaining clean wet flue gas.

[0056] Specifically, the circulating water pump can be adjusted to adjust the spray flow rate of the washing solution sprayed from the flue gas washing device, thereby adjusting the temperature of the clean wet flue gas at the outlet of the flue gas pretreatment subsystem, and also reducing the amount of flue gas washing wastewater generated.

[0057] It should also be noted that the make-up water pump is connected to the pretreatment circulating water tank and the waste heat recovery subsystem respectively, and is used to regularly obtain the required make-up water for the pretreatment circulating water tank from the waste heat recovery subsystem.

[0058] The sewage pump is connected to the pretreatment circulating water tank and the wastewater treatment subsystem respectively, and is used to regularly discharge the tobacco washing wastewater in the pretreatment circulating water tank to the wastewater treatment subsystem. From the above introduction to the operation process of the flue gas pretreatment subsystem, it can be seen that the flue gas pretreatment subsystem has the function of controlling the output of tobacco washing wastewater. Specifically, by adjusting the spray flow in the atomizing spray device, the amount of condensed water in the flue gas in the pretreatment section can be reduced, thereby reducing the amount of tobacco washing wastewater generated. Therefore, the sewage treatment cost is greatly reduced. The flue gas to be treated is processed by the flue gas pretreatment subsystem to obtain clean wet flue gas and then transported to the waste heat recovery subsystem.

[0059] The waste heat recovery subsystem is mainly composed of spray heat exchange sections with preset levels.

[0060] The principle of the spray heat exchange section is: spray water is used to exchange heat with the flue gas to be treated. The flue gas to be treated will release sensible heat in the process of lowering the temperature. The sensible heat released when the flue gas temperature is lowered accounts for a small part of the flue gas heat recovery; at the same time, when the flue gas is lower than the dew point temperature, water in the form of water vapor will precipitate out of the flue gas. When the water in the flue gas undergoes a phase change from gas to liquid, a large amount of latent heat will be released. The large amount of latent heat released is the main part of the flue gas heat recovery.

[0061] The spray heat exchange section provided in the present application includes at least a primary spray heat exchange section and a secondary spray heat exchange section. If necessary, multiple spray sections can be set to recover flue gas heat. Each primary spray heat exchange section includes a spray device. The state parameters of the spray water sprayed by the spray device are adjustable. The state parameters of the spray water mainly include the flow rate and water temperature of the spray water.

[0062] Exemplarily, when the first-level spray heat exchange section wants to recover most of the flue gas heat, the spray flow rate of the spray water in the spray device in the first-level spray heat exchange section is increased accordingly, and the water temperature of the spray water is reduced. That is, the amount of heat recovered in each spray heat exchange section is positively correlated with the amount of spray water and negatively correlated with the water temperature of the spray water. It can be understood that the spray heat exchange section can control the amount of condensed water produced by controlling the degree of reduction in the flue gas temperature. It should be noted that after the clean wet flue gas passes through the first-level spray section, its temperature and humidity are reduced, and the generated condensed water and spray water enter the first-level spray water collection tank slowly. The water in the first-level spray water collection tank is used as the water replenishment of the pretreatment circulating water tank in the flue gas pretreatment subsystem mentioned above, and the excess water in the first-level spray water collection tank can also be reused in the entire waste incineration treatment plant. It can be seen that the first-level spray section can further purify the flue gas and improve the cleanliness of the flue gas. Then, the flue gas with higher purity is input into the secondary spray heat exchange section, and the condensed water and spray water generated in the secondary spray heat exchange section will enter the secondary spray water collecting tank. The water in the secondary spray water collecting tank has higher purity than the water in the primary spray water collecting tank, and can be used as water replenishment for systems with higher water quality requirements.

[0063] The spray heat exchange section can control the temperature drop of the flue gas by controlling the flow rate of the spray water and the water temperature. After the flue gas to be treated passes through the spray heat exchange section, a small amount of sensible heat and a large amount of latent heat will be released to obtain saturated wet flue gas.

[0064] The waste heat recovery subsystem also includes a heat exchanger, which is mainly used to obtain flue gas heat from the spray water obtained after spraying in the spray heat exchange section, and transfer the flue gas heat in the spray water to the external cold source. It should be noted that a heat exchanger can be placed in each spray heat exchange section, or the heat exchanger can be placed in only one spray heat exchange section.

[0065] When a heat exchanger is provided in each spray heat exchange section, the heat of flue gas can be recovered in stages. Specifically, the spray water in the multi-stage spray heat exchange section directly exchanges heat with the flue gas, and the spray water obtained after spraying in each spray heat exchange section is input into the heat exchanger in each section, and the heat is provided by the heat exchanger in each section and the external cold source.

[0066] When only one heat exchanger is provided, it is preferred to provide the heat exchanger in the primary spray heat exchange section. Exemplarily, by setting the state parameters of the spray water in the spray device corresponding to the primary spray heat exchange section, most of the flue gas heat is recovered in the primary spray heat exchange section.

[0067] The waste heat recovery subsystem also includes a waste heat recovery spray water tank and water volume control equipment.

[0068] The waste heat recovery spray water tank is mainly connected to the spray device in the spray heat exchange section to provide spray water for each spray section cycle. That is, the water after spraying in each spray heat exchange section will return to the waste heat recovery spray water tank after heat exchange in the heat exchanger. The water returning to the waste heat recovery spray water tank will become the spray water sprayed into the spray heat exchange section again.

[0069] It should be noted that the water returning from the spray heat exchange section to the waste heat recovery spray water tank not only includes the spray water provided by the waste heat recovery spray water tank to the spray device, but also includes the condensed water precipitated from the flue gas to be treated during the cooling process during the spraying process. The greater the temperature reduction of the flue gas to be treated during the spray heat exchange process, the greater the amount of condensed water precipitated. Therefore, the amount of water returning from the spray heat exchange section to the waste heat recovery spray water tank will be greater than the amount of spray water provided to the spray device.

[0070] For this purpose, the present application configures a water volume control device for the waste heat recovery spray water tank, and the water volume control device is installed on the waste heat recovery spray water tank. The water volume control device will detect whether the amount of circulating water in the waste heat recovery spray water tank exceeds the preset standard amount according to a preset cycle or in real time. When it is detected that the amount of circulating water in the waste heat recovery spray water tank exceeds the preset standard amount, the water volume control device will control the waste heat recovery spray water tank to discharge the circulating water that exceeds the preset standard amount, and the circulating water discharged from the waste heat recovery spray water tank can be reused in the entire waste incineration treatment plant.

[0071] It can be understood that the waste heat recovery spray water tank can provide spray water for the entire waste incineration flue gas waste heat utilization system circulation, and discharge excess circulating water in time to maintain the dynamic balance of circulating water in the entire waste incineration flue gas waste heat utilization system.

[0072] In summary, the waste heat recovery subsystem can reduce the temperature and humidity of the clean wet flue gas output from the flue gas pretreatment subsystem to obtain low-temperature saturated wet flue gas. Finally, the low-temperature saturated wet flue gas processed by the waste heat recovery subsystem is input into the flue gas reheating subsystem.

[0073] The waste heat recovery subsystem recovers most of the flue gas to be treated. However, if the saturated wet flue gas is directly discharged into the flue, it will corrode the flue. Specifically, the temperature of the saturated wet flue gas is relatively low. During the discharge through the flue, the temperature of the saturated wet flue gas may further decrease. At this time, the acidic gas in the saturated wet flue gas will condense into acid liquid during the temperature drop, corroding the flue. In order to avoid the problem of flue corrosion caused by the direct discharge of saturated wet flue gas, the flue gas reheating subsystem is used to treat the saturated wet flue gas before discharge.

[0074] The flue gas reheating subsystem includes a flue gas heat exchanger; the function of the flue gas heat exchanger is to heat the saturated wet flue gas. The working principle of the flue gas heat exchanger in this application is to use flue gas to heat the flue gas. Specifically, the flue gas heat exchanger collects part of the heat in the flue gas to be treated, dynamically heats the saturated wet flue gas input into the flue gas heat exchanger, and then discharges it. The flue gas heat exchanger can be installed at the outlet of the induced draft fan, that is, in the flue where the flue gas to be treated just begins to enter the waste incineration flue gas waste heat utilization system. The initial temperature of the flue gas to be treated is generally 130°~150°. The flue gas heat exchanger will use part of the flue gas obtained from the flue gas to be treated to heat the saturated wet flue gas with a lower temperature at the outlet of the flue gas reheating subsystem.

[0075] The flue gas heat exchanger has a heat exchange regulating function. Specifically, by adding a flue gas bypass channel to the flue gas heat exchanger, the flue gas heat exchanger can have a heat exchange capacity regulating function without adding a fan.

[0076] Optionally, in addition to the flue gas heat exchanger, the flue gas reheating subsystem is also provided with a flue gas flow regulating valve, a heating discharge channel and a bypass channel. The flue gas flow regulating valve may specifically be an electric regulating damper.

[0077] The flue gas flow regulating valve is mainly used to control the flow of saturated wet flue gas flowing into the heating discharge channel and the flue gas bypass channel; the heating discharge channel is connected to the flue gas heat exchanger, and the flue gas flow regulating valve introduces part of the saturated wet flue gas into the flue gas heat exchanger for heating as needed, and the rest is directly introduced into the flue gas bypass channel for direct discharge. Optionally, the heated part of the saturated wet flue gas can be mixed with the saturated wet flue gas with a lower temperature directly discharged from the bypass channel and then discharged to the outside. In this way, during the mixing process, the heated part of the saturated wet flue gas can heat the saturated wet flue gas with a lower temperature discharged from the bypass channel, ensuring that the mixed flue gas is higher than the dew point temperature, and will not condense acid to corrode the flue due to the low temperature, which can reduce the corrosion of the flue and avoid the generation of a large amount of white smoke during discharge.

[0078] It can be seen that the flue gas reheating subsystem does not require an external heat source. By adjusting the flue gas heat exchanger and the flue gas bypass channel through the flue gas flow control valve, the superheat of the flue gas at the outlet of the absorption tower can be increased, thereby solving the problem of flue corrosion.

[0079] It should also be noted that, through the flue gas reheating subsystem in the present application, the temperature of the saturated wet flue gas can be raised by about 20°, which can avoid excessive flue gas temperature rise and reduce heat loss. In addition, the flue gas reheating subsystem provided in the present application adopts a flue gas heating flue gas method, which can heat the saturated wet flue gas without an external heat source. Steam heating is usually used in the known technology, and a steam heating device needs to be set up separately. In addition, the steam heating method has a high energy consumption. In comparison, the flue gas reheating method provided in the present application has a lower energy consumption.

[0080] The present application heats the low-temperature saturated wet flue gas output from the waste heat recovery subsystem through the flue gas reheating subsystem, which can increase the superheat of the flue gas and reduce the corrosion of the flue and chimney by the flue gas.

[0081] In summary, the waste incineration flue gas waste heat utilization system provided by the present application is that the flue gas to be treated is pre-treated by the flue gas pretreatment subsystem, and the condensation amount of the flue gas in the pretreatment section is reduced by adjusting the spray flow rate, and the amount of sewage generated is reduced, thereby reducing the cost of sewage treatment. Afterwards, the present application adopts the method of controlling the spray water state parameters in the spray device to recover most of the heat of the flue gas to be treated, thereby improving the efficiency of flue gas heat recovery. Finally, the saturated wet flue gas obtained is input into the flue gas reheating subsystem, and the flue gas reheating subsystem with a heat exchange regulation function is provided, specifically by providing a flue gas heat exchanger and a flue gas bypass channel to increase the superheat of the flue gas at the outlet of the absorption tower, thereby solving the problem of flue corrosion.

[0082] Optionally, the primary spray water collection tank in the waste heat recovery subsystem can replenish water for the pretreatment circulating water tank. Specifically, the primary spray water collection tank is connected to the pretreatment circulating water tank, and the pretreatment circulating water tank includes a liquid level monitoring device. When the liquid level monitoring device detects that the liquid level in the pretreatment circulating water tank reaches the water replenishment level, a water replenishment prompt signal is generated and sent to the primary spray water collection tank.

[0083] After receiving the water replenishment prompt signal, the first-stage spray water collecting tank will input the first-stage spray water into the pretreatment circulating water tank as replenishment water.

[0084] It is understandable that the state of the spray water in the spray heat exchange section of the waste heat recovery subsystem will affect the amount of condensed water produced. In order to ensure the stable production of condensed water, the liquid level feedback mechanism described above is adopted to ensure that the circulating water in the entire waste incineration flue gas waste heat utilization system maintains a dynamic balance.

[0085] Optionally, the waste incineration flue gas waste heat utilization system also includes a wastewater treatment subsystem connected to the flue gas pretreatment subsystem, and the wastewater treatment subsystem treats polluted sediments produced by washing in the pretreatment circulating water tank according to a preset cycle.

[0086] Specifically, the wastewater treatment system includes an alkali solution preparation device, a continuous sewage discharge device, and a periodic sewage discharge device.

[0087] The alkali solution preparation device is mainly used to provide alkali solution for the pretreatment circulating water tank to adjust the pH value in the pretreatment circulating water tank. The water in the pretreatment circulating water tank needs to be circulated for spraying the flue gas to be treated. In this process, the pretreatment circulating water tank maintains the concentration of pollutants in the circulating water through water replenishment and continuous sewage discharge device.

[0088] The pollutants and sewage in the pre-treatment circulating water tank will be discharged through the continuous sewage discharge device in the wastewater treatment system. After the sewage and pollutants are treated by the wastewater treatment system, they will be discharged through the regular sewage discharge device. The sludge generated by the sewage and pollutants discharged from the pre-treatment circulating water tank after being treated by the wastewater treatment system will be directly treated in the field.

[0089] Optionally, the waste incineration flue gas waste heat utilization system also includes a heating section connected to the waste heat recovery subsystem, the heating section mainly includes a hot water network system, the hot water network system is connected to the heat exchanger in the waste heat recovery subsystem, and the flue gas heat recovered in the heat exchanger is used to heat the hot water network return water in the hot water network system to provide heat to the outside. The heating section also includes a steam heater and a temperature detection device, the temperature detection device is used to detect the temperature of the hot water network, when the temperature detection device detects that the hot water network return water that has absorbed the flue gas heat does not reach the preset heating temperature, the steam heater will be used to heat the hot water network return water again.

[0090] It should be noted that the waste incineration flue gas waste heat utilization system provided by this application can be operated throughout the year. In the heating season, it can provide heating to the outside by exchanging heat with the heat network water system. In the non-heating season, the flue gas heat recovered by the system can heat the condensate in the steam turbine, thereby saving the steam extraction consumption of the steam turbine deaerator and low-pressure heater, and improving the operating income of the corresponding project of the steam turbine.

[0091] In addition, the flue gas heat recovered in the waste incineration flue gas waste heat utilization system can also be used for hot water supply, steam production, air preheating, power generation and other aspects.

[0092] For hot water supply, the recovered heat can be directly used to heat domestic water for daily needs such as bathing and washing hands. It can be used not only in industrial sites, but also in hotels, schools and residential areas.

[0093] For steam production, the heat in the flue gas is converted into steam through the waste heat boiler, which can be used in various industrial processes, such as material drying, reactor heating, etc. The produced steam can also be used to drive the steam turbine to generate electricity, further utilizing the heat energy to convert into electrical energy.

[0094] For air preheating, the recovered flue gas heat can preheat the combustion air, improving combustion efficiency and energy saving.

[0095] See also Figure 2 , a diagram showing an example of the system composition structure of a waste incineration flue gas waste heat utilization system provided in this application.

[0096] The waste incineration flue gas waste heat utilization system provided in the present application includes a flue gas pretreatment subsystem, a waste heat recovery subsystem and a flue gas reheating subsystem.

[0097] The flue gas pretreatment subsystem connected to the waste heat recovery subsystem includes a flue gas pretreatment tower, an atomizing nozzle, a lifting pump, a pretreatment circulating water tank, a thermocouple, a liquid level meter, etc. The pretreatment circulating water tank contains circulating water including alkali solution.

[0098] Specifically, the pretreatment circulating water tank delivers the washing solution to the atomizing nozzle in the flue gas pretreatment tower through the lifting pump. The alkaline circulating water sprayed from the atomizing nozzle will carry the particulate matter and acidic pollutants washed out from the flue gas to be treated and return to the pretreatment circulating water tank again. The flue gas to be treated after being treated by the flue gas pretreatment subsystem has high flue gas cleanliness, slightly lower temperature and increased humidity.

[0099] The flue gas pretreatment subsystem processes the flue gas to be treated into clean wet flue gas and then discharges the clean wet flue gas into the waste heat recovery subsystem through the flue gas pretreatment tower.

[0100] The waste heat recovery subsystem includes a primary spray heat exchange section and a secondary spray heat exchange section. The waste heat recovery subsystem may specifically include a primary spray section, a primary spray water collecting tank, a primary spray device, a primary heat exchanger, a secondary spray section, a secondary spray device, a secondary spray water collecting tank, a secondary heat exchanger, a lifting pump, a thermocouple, a liquid level meter, a waste heat recovery spray water tank and other components.

[0101] The waste heat recovery spray water tank transports the spray water to the primary spray device and the secondary spray device through the lifting pump, and the primary spray device and the secondary spray device spray the water to the primary spray section and the secondary spray section respectively. The spray water exchanges heat with the clean wet flue gas discharged from the flue gas pretreatment subsystem, and the temperature of the clean wet flue gas is reduced. After it is lower than the dew point temperature, condensed water is precipitated. The precipitated condensed water is mixed with the spray water and enters the primary spray water collecting tank. The water in the primary spray water collecting tank may enter the pretreatment circulating water tank in the flue gas pretreatment subsystem as make-up water. The specific amount of make-up water entering the primary spray water collecting tank is controlled according to the pretreatment circulating water tank. The water in the primary spray water collecting tank will enter the primary heat exchanger, which can subsequently exchange heat with the return water from the heating network to provide heating to the outside by heating the return water from the heating network. The water after heat exchange with the heat exchanger will recover the waste heat in the spray water tank; the spray water in the secondary spray section will enter the secondary spray water collecting tank, and the water in the secondary spray water collecting tank will enter the secondary heat exchanger, which can subsequently exchange heat with the steam supplementary heat device. After heat exchange, the spray water will also enter the waste heat recovery spray water tank, and the spray water after heat exchange with the primary heat exchanger and the secondary heat exchanger will enter the waste heat recovery spray water tank, and subsequently provide spray water for the primary spray device and the secondary spray device.

[0102] The waste heat recovery subsystem discharges the saturated wet flue gas from the reaction tower into the flue gas reheating subsystem.

[0103] The flue gas reheating subsystem includes a flue gas heat exchanger and a flue gas heat exchanger bypass. When the amount of saturated wet flue gas is small, a part of the saturated wet flue gas can be discharged from the bypass through the electric damper, and the other part of the saturated wet flue gas can be input into the flue gas heat exchanger for heating. The overall temperature rise of the saturated flue gas is controlled at about 20°C. The saturated wet flue gas temperature rise of about 20°C can ensure that it has a certain degree of superheat, and there will be no condensation water to corrode the flue. In addition, the bypass design can prevent the flue gas from heating up too high, thereby better reducing heat loss.

[0104] In addition, the waste incineration flue gas waste heat utilization system provided in the present application also includes a steam turbine condensate heat exchanger, which obtains heat from the flue gas to be treated and heats the steam turbine condensate in the steam turbine condensate heat exchanger.

[0105] In addition, the waste incineration flue gas waste heat utilization system provided in the present application operates throughout the year, heating the hot water network system in the heating season and providing heat to the steam turbine condensate heat exchanger to heat the steam turbine condensate in the non-heating season.

[0106] Optionally, the present application also provides a flue gas waste heat absorption tower, which includes a tower body and the waste incineration flue gas waste heat utilization system described above.

[0107] The tower body comprises a first flue section and a second flue section which are connected in sequence. Specifically, the flue gas pretreatment subsystem and the flue gas reheating subsystem are arranged in the first flue section, and the waste heat recovery subsystem is arranged in the second flue section.

[0108] After the saturated wet flue gas is processed in the second flue section, the saturated wet flue gas can be transported through a transport pipeline to the flue gas reheating subsystem in the first flue section for treatment and then discharged.

[0109] Specifically, the material of the flue section can be glass fiber reinforced plastic fiberglass, commonly known as fiberglass, which has many advantages such as light weight, high strength, corrosion resistance, heat preservation, insulation, sound insulation, etc. Its strength is equivalent to that of steel, and it contains glass components, and also has the color, shape, corrosion resistance, electrical insulation, heat insulation and other properties of glass, which can increase the service life of the flue gas waste heat absorption tower, reduce the energy loss of flue gas in the flue gas waste heat absorption tower, and improve the heat recovery rate.

Claims

1. A waste incineration flue gas waste heat utilization system, It is characterized in that It includes a waste heat recovery subsystem and a flue gas reheating subsystem and a flue gas pretreatment subsystem connected to the waste heat recovery subsystem; After being discharged from the outlet of the induced draft fan, the flue gas to be treated is sequentially processed by the flue gas pretreatment subsystem, the waste heat recovery subsystem and the flue gas reheating subsystem; Wherein, the flue gas pretreatment subsystem includes a flue gas scrubber, a circulating water pump, a water supply pump, a sewage pump and a pretreatment circulating water tank; The flue gas to be treated enters the flue gas pretreatment subsystem through the flue duct; the flue gas scrubbing device obtains a scrubbing solution from the pretreatment circulating water tank through the circulating water pump, and uses the scrubbing solution to spray the flue gas to be treated, thereby obtaining flue gas scrubbing wastewater including acidic pollutants and particulate matter and clean wet flue gas; The flue gas pretreatment subsystem transports the clean wet flue gas to the waste heat recovery subsystem through the flue; The water replenishment pump is connected to the pretreatment circulating water tank and the waste heat recovery subsystem respectively, and is used to obtain the replenishment water required by the pretreatment circulating water tank from the waste heat recovery subsystem; The sewage pump is connected to the pretreatment circulating water tank and the wastewater treatment subsystem respectively, and is used to regularly discharge the tobacco washing wastewater in the pretreatment circulating water tank to the wastewater treatment subsystem.

2. The waste incineration flue gas waste heat utilization system according to claim 1, It is characterized in that The waste heat recovery subsystem includes a spray heat exchange section with preset levels; The preset level of spray heat exchange sections at least includes a primary spray heat exchange section and a secondary spray heat exchange section, each section is provided with a spray device, and the spray water state parameters of the spray device are set according to the state of the initial flue gas input into each spray heat exchange section; the spray device controls the temperature drop amplitude of the flue gas by controlling the state parameters of the spray water in the spray heat exchange section, so that the flue gas to be treated is sprayed and heat exchanged through the primary spray heat exchange section and the secondary spray heat exchange section in turn to obtain saturated wet flue gas; the heat exchanger in the waste heat recovery subsystem obtains flue gas heat from the spray water obtained after spraying the spray heat exchange section.

3. The waste incineration flue gas waste heat utilization system according to claim 1, It is characterized in that The flue gas heat exchanger in the flue gas reheating subsystem is arranged in the flue; The flue gas reheating subsystem is provided with a flue gas flow regulating valve, which is respectively connected to the heating discharge channel and the flue gas bypass channel, and is used to control the flow of saturated wet flue gas flowing into the heating discharge channel and the flue gas bypass channel; the heating discharge channel introduces the saturated wet flue gas into the flue gas heat exchanger, and the flue gas heat exchanger collects the heat of the flue gas to be treated flowing through the flue, and uses the heat to heat the saturated wet flue gas flowing in and then discharges it; The flue gas bypass channel is used to directly discharge the inflowing saturated wet flue gas.

4. The waste incineration flue gas waste heat utilization system according to claim 3, It is characterized in that When the load of the waste incineration power plant where the waste incineration flue gas waste heat utilization system is located is lower than a preset threshold, the flue gas reheating subsystem will mix and discharge the superheated flue gas obtained by heating the saturated wet flue gas through the flue gas heat exchanger with the saturated wet flue gas directly discharged through the flue gas bypass channel.

5. The waste incineration flue gas waste heat utilization system according to claim 2, It is characterized in that The waste heat recovery subsystem also includes a waste heat recovery spray water tank and a water volume control device; The waste heat recovery spray water tank is connected to the spray device to provide spray water for the spray device; The water volume control device is installed on the waste heat recovery spray water tank; the water volume control device detects whether the circulating water volume in the waste heat recovery spray water tank exceeds the preset standard volume according to a preset period. When it is detected that the circulating water volume exceeds the preset standard volume, the drainage device of the waste heat recovery spray water tank is controlled to discharge the circulating water exceeding the preset standard volume.

6. The waste incineration flue gas waste heat utilization system according to claim 2, It is characterized in that The primary spray water collecting tank in the waste heat recovery subsystem is connected to the pretreatment circulating water tank; When the liquid level monitoring device in the pretreatment circulating water tank detects that the liquid level of the pretreatment circulating water tank reaches the water replenishment level, a water replenishment prompt signal is generated and the water replenishment prompt signal is sent to the primary spray water collecting tank; After receiving the water replenishment prompt signal, the first-level spray water collecting tank inputs the first-level spray water into the pretreatment circulating water tank.

7. The waste incineration flue gas waste heat utilization system according to claim 1, It is characterized in that Also included is a wastewater treatment subsystem connected to the flue gas pretreatment subsystem; The wastewater treatment subsystem is used to treat the smoke washing wastewater and polluted sediments generated after washing the smoke to be treated in the pretreatment circulating water tank according to a preset cycle.

8. The waste incineration flue gas waste heat utilization system according to claim 2, It is characterized in that It also includes a heating section connected to the waste heat recovery subsystem; The heating section includes a heating network water system; The heating network water system is connected to the heat exchanger; the heating network water in the heating network water system absorbs the flue gas heat recovered in the heat exchanger.

9. The waste incineration flue gas waste heat utilization system according to claim 8, It is characterized in that The heat network water system also includes a temperature detection device and a steam supplementary heater; When the temperature detection device detects that the temperature of the hot network water that absorbs the heat of the flue gas does not reach the preset heating temperature, the steam heater is used to heat the hot network water that absorbs the heat of the flue gas to the preset heating temperature.

10. The waste incineration flue gas waste heat utilization system according to claim 8, It is characterized in that It also includes a steam turbine condensate heat exchanger connected to the flue gas pretreatment subsystem; The flue gas to be treated first passes through the turbine condensate heat exchanger after being discharged from the induced draft fan outlet. The turbine condensate heat exchanger obtains heat from the flue gas to be treated and heats the turbine condensate in the turbine condensate heat exchanger.

11. The waste incineration flue gas waste heat utilization system according to claim 10, It is characterized in that The waste incineration flue gas waste heat utilization system operates throughout the year, the heat network water system operates in the heating season, and the steam turbine condensate heat exchanger operates in the non-heating season.

12. A flue gas waste heat absorption tower, comprising a tower body, It is characterized in that It also includes a waste incineration flue gas waste heat utilization system as described in any one of claims 1 to 11; The tower body comprises a first flue section and a second flue section connected in sequence; The flue gas pretreatment subsystem and the flue gas reheating subsystem are arranged in the first flue section, and the waste heat recovery subsystem is arranged in the second flue section.

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