Exhaust gas treatment system for a dye drying process and spray drying tower system

Abstract

The application provides a tail gas treatment system for a dye drying process and a spray drying tower system. The tail gas treatment system comprises a cyclone separator, a bag filter, a waste heat recovery device, a condenser and a steam heater. The cyclone separator is connected to a tail gas outlet of the spray drying tower, and the bag filter is connected to a gas outlet of the cyclone separator to filter dye powder particles in the tail gas after cyclone separation. The waste heat recovery device comprises a first flow path and a second flow path, the first flow path and the second flow path can form heat exchange, and the first flow path and the second flow path are not communicated in the waste heat recovery device. The first flow path of the waste heat recovery device is connected to the bag filter, so that the tail gas enters the first flow path of the waste heat recovery device from the bag filter. The first flow path of the waste heat recovery device is connected to the condenser through a circulation loop, and the condenser is connected to the second flow path of the waste heat recovery device through the circulation loop, so that the tail gas can flow back to the waste heat recovery device after being dehumidified by the condenser and being preliminarily heated.

Description

Technical Field

[0001] This application relates to the field of exhaust gas treatment technology, and in particular to an exhaust gas treatment system and a spray drying tower system for dye drying processes. Background Technology

[0002] Compared to liquid dyes, powdered dyes offer better quality stability, greater formulation flexibility, and higher concentrations of active ingredients. Furthermore, the storage, packaging, and transportation costs of powdered dyes are relatively lower. Therefore, the modern dye industry predominantly chooses to process dye products into powder form.

[0003] Currently, the commonly used process for converting liquid slurry into powder is spray drying. This process requires the evaporation of a large amount of water and generates a significant amount of high-temperature exhaust gas. However, in existing technologies, this high-temperature exhaust gas is often treated by an exhaust gas treatment device before being directly released, resulting in a significant waste of its thermal energy. Furthermore, a single exhaust gas treatment device is insufficient to remove the various pollutants in the exhaust gas. Therefore, there is an urgent need to design a comprehensive exhaust gas treatment system suitable for dye production processes. Utility Model Content

[0004] This application is made in view of the aforementioned state of the prior art. The purpose of this application is to provide a tail gas treatment system for a dye drying process, which can recover part of the heat energy in the tail gas generated by the dye spray drying process and reduce the content of various pollutants in the tail gas.

[0005] This application also provides a spray drying tower system including the above-described exhaust gas treatment system.

[0006] This application provides a tail gas treatment system for a dye drying process, which treats the tail gas generated by a spray drying tower. The system includes a cyclone separator, a bag filter, a waste heat recovery unit, a condenser, and a steam heater.

[0007] The cyclone separator is connected to the exhaust gas outlet of the spray drying tower, and the bag filter is connected to the gas outlet of the cyclone separator to filter dye powder particles in the exhaust gas after cyclone separation.

[0008] The waste heat recovery device includes a first flow path and a second flow path, which are capable of heat exchange, and the first flow path and the second flow path are not connected internally within the waste heat recovery device.

[0009] The first flow path of the waste heat recovery unit is connected to the bag filter, allowing exhaust gas to enter the first flow path of the waste heat recovery unit from the bag filter.

[0010] The first flow path of the waste heat recovery unit is connected to the condenser via the circulation loop, and the condenser is connected to the second flow path of the waste heat recovery unit via the circulation loop, so that the exhaust gas, after being dehumidified by the condenser, can flow back to the waste heat recovery unit and be initially heated.

[0011] The waste heat recovery unit is also connected to the steam heater, which is connected to the hot gas inlet of the spray drying tower, so that the gas that has been preheated is reheated by the steam heater before being introduced into the spray drying tower.

[0012] In at least one possible implementation, the exhaust gas treatment system for the dye drying process further includes an exhaust gas processor disposed downstream of the first flow path of the waste heat recovery unit and upstream of the second flow path, to treat a portion of the pollutants in the exhaust gas.

[0013] In at least one possible implementation, the exhaust gas treatment system for the dye drying process further includes a cooling tower, wherein coolant in the condenser circulates between the cooling tower and the condenser to maintain the dehumidification capacity of the condenser.

[0014] In at least one possible implementation, the coolant is room temperature water.

[0015] In at least one possible implementation, the second flow path of the waste heat recovery unit is also connected to a fresh air duct to allow fresh air to be introduced into the spray drying tower after the waste heat recovery unit has been preheated.

[0016] In at least one possible implementation, the fresh air duct is equipped with an air filter to filter impurities in the fresh air.

[0017] In at least one possible implementation, a first fan is provided between the bag filter and the waste heat recovery unit, a second fan is provided between the waste heat recovery unit and the exhaust gas processor, and a third fan is provided between the waste heat recovery unit and the steam heater.

[0018] In at least one possible implementation, the first fan is an induced draft fan, the second fan is an exhaust fan, and the third fan is an supplied draft fan.

[0019] In at least one possible implementation, one or more of the pipelines from the spray drying tower to the cyclone separator, the cyclone separator to the bag filter, the bag filter to the waste heat recovery unit, and the waste heat recovery unit to the steam heater are provided with insulation sleeves to reduce heat transport loss.

[0020] This application also provides a spray drying tower system, which includes a spray drying tower and the aforementioned exhaust gas treatment system for the dye drying process.

[0021] The exhaust gas outlet of the spray drying tower is connected to the cyclone separator, and the hot gas inlet of the spray drying tower is connected to the steam heater.

[0022] The exhaust gas treatment system and spray drying tower system for dye drying processes provided in this application can recover and utilize the heat in the exhaust gas discharged from the spray drying tower, thereby reducing the energy consumption of the spray drying process. Furthermore, the technical solution of this application can dehumidify at least a portion of the exhaust gas, reheat it, and return it to the spray drying tower, reducing direct emissions of the exhaust gas. Attached Figure Description

[0023] Figure 1 This is a simplified structural diagram of a spray drying tower system according to one embodiment of this application.

[0024] Explanation of reference numerals in the attached figures

[0025] 100 spray drying tower

[0026] 10 Cyclone Separator

[0027] 20 Baghouse Dust Collectors

[0028] 30 Waste Heat Recovery Unit

[0029] 40 Exhaust Gas Processor

[0030] 50 Condenser

[0031] 60 Cooling Tower

[0032] 70 Steam heater

[0033] 80 Air Filter

[0034] 91 First Wind Turbine

[0035] 92 Second Fan

[0036] 93 Third Fan

[0037] 200-cycle loop Detailed Implementation

[0038] Exemplary embodiments of this application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement this application only, and are not intended to exhaustively describe all possible methods of this application, nor to limit the scope of this application.

[0039] Embodiments of this application provide a tail gas treatment system (hereinafter, sometimes simply referred to as a "tail gas treatment system") for a dye drying process, which can be used to treat the tail gas generated by the spray drying tower in the dye drying process. Figure 1 As shown, the exhaust gas treatment system may include a cyclone separator 10, a bag filter 20, a waste heat recovery unit 30, an exhaust gas processor 40, a condenser 50, a cooling tower 60, a steam heater 70, and an air filter 80. The exhaust gas treatment system can be connected to the gas outlet and gas inlet of the spray drying tower 100, respectively.

[0040] For example, liquid dye slurry and hot air can be introduced into spray drying tower 100 from the top or upper part. Spray drying tower 100 atomizes the liquid slurry into tiny droplets. These droplets rapidly evaporate upon contact with hot air inside the tower, while the dye particles dissolved or suspended in the droplets gradually concentrate, aggregate, and solidify during this process, ultimately forming dry solid dye powder particles. The gas-solid system of solid dye powder particles and high-temperature exhaust gas (the exhaust gas has a lower temperature and higher humidity than the hot air introduced into the spray drying tower, but its temperature is still above room temperature) can be discharged from the bottom or lower part of spray drying tower 100. It is understood that the operation process of the spray drying tower described above can be modified depending on the type of drying tower; for example, some types of spray drying towers can discharge exhaust gas from the upper part of the tower.

[0041] The inlet of the cyclone separator 10 can be connected to the exhaust outlet of the spray drying tower. The solid dye powder particles discharged from the spray drying tower 100 and the high-temperature exhaust gas can enter the cyclone separator 10 for primary filtration. The cyclone separator 10 can use the centrifugal force generated by the high-speed rotating airflow to separate most of the powder particles (most of the particles with relatively large particle sizes) from the gas-solid system.

[0042] The baghouse dust collector 20 can be connected to the gas outlet of the cyclone separator 10. The exhaust gas treated by the cyclone separator 10 can be further introduced into the baghouse dust collector 20. The filter bags in the baghouse dust collector 20 can perform secondary filtration on the residual powder particles (relatively small particles, such as particles with a diameter of less than 5 to 10 micrometers) in the exhaust gas. It can be understood that the combination of the primary filtration of the cyclone separator 10 and the secondary filtration of the baghouse dust collector 20 can separate most of the powder particles in the gas-solid system.

[0043] In one experimental example, after the gas-solid system output from the spray drying tower 100 is successively treated by the cyclone separator 10 and the bag filter 20, the dust emission in the exhaust gas can be reduced to less than 15 mg / m³. 3 (milligrams per cubic meter).

[0044] The exhaust gas, after being filtered twice, can enter the waste heat recovery unit 30, which can recover heat from the exhaust gas (for example, the waste heat recovery unit 30 can be equipped with a heat pipe structure) and use the recovered heat to preheat the gas that will be introduced into the spray drying tower 100.

[0045] The waste heat recovery unit 30 may include a first flow path and a second flow path. Heat exchange can occur between the gas in the first flow path and the gas in the second flow path. The first and second flow paths are not connected within the waste heat recovery unit 30; that is, the gas in the first flow path and the gas in the second flow path do not directly exchange within the waste heat recovery unit 30 (they can be connected via external circulation in subsequent pipelines, as described later). For example, the outer wall of the first flow path can contact the internal heat pipe structure of the waste heat recovery unit 30, and the heat pipe structure can further contact the outer wall of the second flow path to achieve heat exchange between the first and second flow paths.

[0046] Preferably, a first fan 91 can be installed between the bag filter 20 and the waste heat recovery unit 30 to extract the exhaust gas treated by the bag filter 20 and send it into the waste heat recovery unit 30. More preferably, the first fan 91 can be an induced draft fan, which typically has good heat resistance and dust prevention performance and is suitable for operating conditions where the exhaust gas temperature is high and contains a small amount of dust.

[0047] like Figure 1 As shown, the waste heat recovery unit 30 can also be connected to the exhaust gas processor 40, the condenser 50, the steam heater 70 and the air filter 80 respectively, so that the waste heat recovery unit 30 can input filtered exhaust gas and / or fresh air; it can output exhaust gas after heat recovery and hot air flow after preliminary heating respectively.

[0048] Specifically, such as Figure 1 As shown, the exhaust gas processor 40 can be connected downstream of the first flow path of the waste heat recovery unit 30, and the exhaust gas processor 40 can be located upstream of the second flow path. The exhaust gas processor 40 can be used to treat a portion of the exhaust gas that does not need to be recycled, enabling the exhaust gas to meet or exceed emission standards. The exhaust gas processor 40 can treat various pollutants in the incoming exhaust gas. For example, the exhaust gas processor 40 may include a water film dust collector, a high-energy particle generator, etc. The water film dust collector can be used to remove residual dust in the exhaust gas, and the high-energy particle generator can be used to decompose volatile organic compounds (VOCs) in the exhaust gas.

[0049] Preferably, a second fan 92 can be installed between the waste heat recovery unit 30 and the exhaust gas processor 40 to extract a portion of the exhaust gas from which heat energy has been recovered for pollutant treatment. More preferably, the second fan 92 can be an exhaust fan.

[0050] A circulation loop 200 can be provided between the waste heat recovery unit 30 and the condenser 50. The first flow path of the waste heat recovery unit 30 can be connected to the condenser 50 via the circulation loop 200. At least a portion (of the exhaust gas that needs to be reused) of the waste heat recovery unit 30 can be condensed and dehumidified in the condenser 50. It is understood that the drying process in the spray drying tower 100 will increase the humidity of the exhaust gas, and higher humidity is not conducive to material drying. The condenser 50 can be connected to the second flow path of the waste heat recovery unit 30 via the circulation loop 200. The exhaust gas dehumidified by the condenser 50 can enter the waste heat recovery unit 30 via the circulation loop 200, where it is initially heated, and then enters the steam heater 70 for secondary heating to meet the usage requirements of the spray drying tower 100.

[0051] The condenser 50 can be connected to the cooling tower 60, and the coolant in the condenser 50 can circulate between the condenser 50 and the cooling tower 60, enabling the cooling tower 60 to cool the condenser 50 and maintain its condensation and dehumidification capabilities. Preferably, the coolant used in the condenser 50 and the cooling tower 60 can be room temperature water, since the temperature of the exhaust gas is typically 55 to 75 degrees Celsius, using room temperature water as the coolant can achieve a cooling effect at a lower cost.

[0052] It is understandable that, due to exhaust gas losses and changes in production efficiency, relying solely on exhaust gas recovery may not meet production needs under certain conditions, thus requiring the timely replenishment of fresh air. The waste heat recovery unit 30 can also be connected to a fresh air duct. The fresh air duct can be equipped with an air filter 80 to filter impurities in the fresh air. The air filtered by the air filter 80 can be preheated by the waste heat recovery unit 30 and then reheated by the steam heater 70 before being introduced into the spray drying tower 100.

[0053] It is understandable that the recycling rate of exhaust gas and the amount of fresh air introduced can be flexibly adjusted based on actual requirements of the spray drying tower. Under some operating conditions, exhaust gas or fresh air alone can be used as the heat source for the spray drying tower.

[0054] Preferably, in the exhaust gas discharged after heat recovery by the waste heat recovery unit 30, the proportion of exhaust gas entering the condenser 50 for recycling can be 50% to 100%, that is, the proportion of exhaust gas entering the exhaust gas processor 40 for pollutant treatment can be 0% to 50%. More preferably, the proportion of fresh air in the hot air introduced into the spray drying tower 100 can be 0% to 50%.

[0055] Preferably, the exhaust gas processor 40 can be connected to the recirculation loop 200 and located upstream of the intake end of the condenser 50, and the air filter 80 can be connected to the recirculation loop and located downstream of the condenser 50.

[0056] Preferably, a third fan 93 can be provided between the waste heat recovery unit 30 and the steam heater 70 to send the preheated hot air into the steam heater 70 for secondary heating. More preferably, the third fan 93 can be a blower.

[0057] Preferably, one or more of the following pipelines may be provided with insulation cotton sleeves to reduce heat transport loss: the pipeline from spray drying tower 100 to cyclone separator 10, the pipeline from cyclone separator 10 to bag filter 20, the pipeline from bag filter 20 to waste heat recovery unit 30, and the pipeline from waste heat recovery unit 30 to steam heater 70.

[0058] Compared to methods that directly discharge exhaust gas without recovering its heat, the technical solution provided by the embodiments of this application can reduce the amount of steam used in the steam heater 70 by recovering and utilizing the waste heat in the exhaust gas. In one experimental example, the technical solution of this application can reduce the amount of steam used by 10% to 40%.

[0059] Embodiments of this application also provide a spray drying tower system, which may include the exhaust gas treatment system of the dye drying process described above and a spray drying tower 100. The exhaust gas outlet of the spray drying tower 100 may be connected to the cyclone separator 10 of the exhaust gas treatment system, and the hot gas inlet of the spray drying tower 100 may be connected to the steam heater 70 of the exhaust gas treatment system.

[0060] The following is a brief description of some of the beneficial effects of the above-described embodiments of this application.

[0061] The exhaust gas treatment system and spray drying tower for dye drying processes provided in this application can recover and utilize the heat in the exhaust gas discharged from the spray drying tower, thereby reducing the energy consumption of the spray drying process. Simultaneously, the technical solution of this application can also dehumidify at least a portion of the exhaust gas, reheat it, and return it to the spray drying tower, reducing direct emissions of the exhaust gas. This technical solution can flexibly adjust the exhaust gas recovery rate, exhaust gas treatment and emission volume, and fresh air intake according to the actual operating requirements of the spray drying tower, effectively addressing various operating conditions of the spray drying tower.

[0062] It is understood that, in this application, when the number of parts or components is not specifically limited, the number can be one or more, where multiple refers to two or more. For cases where the number of parts or components shown in the drawings and / or described in the specification is, for example, two, three, four, etc., this specific number is generally exemplary and not restrictive, and can be understood as multiple, i.e., two or more; however, this does not mean that this application excludes the case of one.

[0063] It should be understood that the above embodiments are merely exemplary and are not intended to limit this application. Those skilled in the art can make various modifications and changes to the above embodiments under the teachings of this application without departing from the scope of this application.

Claims

1. A tail gas treatment system for a dye drying process, characterized in that, Includes cyclone separators, bag filters, waste heat recovery units, condensers, and steam heaters. The cyclone separator is connected to the exhaust gas outlet of the spray drying tower, and the bag filter is connected to the gas outlet of the cyclone separator to filter dye powder particles in the exhaust gas after cyclone separation. The waste heat recovery device includes a first flow path and a second flow path, which are capable of heat exchange, and the first flow path and the second flow path are not connected internally within the waste heat recovery device. The first flow path of the waste heat recovery unit is connected to the bag filter, allowing exhaust gas to enter the first flow path of the waste heat recovery unit from the bag filter. The first flow path of the waste heat recovery unit is connected to the condenser via a circulation loop, and the condenser is connected to the second flow path of the waste heat recovery unit via the circulation loop, so that the exhaust gas, after being dehumidified by the condenser, can flow back to the waste heat recovery unit and be initially heated. The waste heat recovery unit is also connected to the steam heater, which is connected to the hot gas inlet of the spray drying tower, so that the gas that has been preheated is reheated by the steam heater before being introduced into the spray drying tower.

2. The exhaust gas treatment system for dye drying process according to claim 1, characterized in that, It also includes an exhaust gas processor, which is located downstream of the first flow path of the waste heat recovery unit and upstream of the second flow path, to treat a portion of the pollutants in the exhaust gas.

3. The exhaust gas treatment system for dye drying process according to claim 1, characterized in that, It also includes a cooling tower, through which the coolant in the condenser circulates between the cooling tower and the condenser to maintain the dehumidification capacity of the condenser.

4. The exhaust gas treatment system for dye drying process according to claim 3, characterized in that, The coolant is room temperature water.

5. The exhaust gas treatment system for dye drying process according to claim 1, characterized in that, The second flow path of the waste heat recovery unit is also connected to a fresh air duct to allow fresh air to be introduced into the spray drying tower after it has been preheated in the waste heat recovery unit.

6. The exhaust gas treatment system for a dye drying process according to claim 5, characterized in that, The fresh air duct is equipped with an air filter to filter impurities in the fresh air.

7. The exhaust gas treatment system for dye drying process according to claim 2, characterized in that, A first fan is provided between the bag filter and the waste heat recovery unit, a second fan is provided between the waste heat recovery unit and the exhaust gas processor, and a third fan is provided between the waste heat recovery unit and the steam heater.

8. The exhaust gas treatment system for a dye drying process according to claim 7, characterized in that, The first fan is an induced draft fan, the second fan is an exhaust fan, and the third fan is a forced draft fan.

9. The exhaust gas treatment system for a dye drying process according to claim 1, characterized in that, One or more of the following pipelines are provided with insulation cotton sleeves to reduce heat transport loss: the pipeline from the spray drying tower to the cyclone separator, the pipeline from the cyclone separator to the bag filter, the pipeline from the bag filter to the waste heat recovery unit, and the pipeline from the waste heat recovery unit to the steam heater.

10. A spray drying tower system, characterized in that, Includes a spray drying tower and a tail gas treatment system for a dye drying process as described in any one of claims 1 to 9. The exhaust gas outlet of the spray drying tower is connected to the cyclone separator, and the hot gas inlet of the spray drying tower is connected to the steam heater.

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