Closed-loop type hydrothermal recovery device of carbon black granulating and drying system

Abstract

The invention relates to the technical field of energy conservation and environmental protection in the carbon black production process, and discloses a closed loop type hydrothermal recovery device of a carbon black granulation drying system, which solves the problems in the background technology and comprises a separator, a condensation recoverer, a circulating treatment unit and a water treatment unit. The separator is connected with a dryer tail gas outlet and used for recycling carbon black in tail gas. The condensation recoverer is connected with a gas outlet of the separator and is used for cooling tail gas to separate out condensed water and recovering heat. And the circulating treatment unit comprises a demister, a circulating fan and a heater which are connected in sequence to form gas closed-loop circulation to send the purified gas back to the drying machine. And the water treatment unit is connected with a condensed water outlet of the condensation recoverer, and purified condensed water is recycled as a cooling water source. Through closed-loop circulation design, sensible heat and latent heat of tail gas are recycled, meanwhile, condensate water is recycled, and the effects of saving energy, reducing consumption, saving water, reducing emission and eliminating white smoke pollution are achieved.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving and environmental protection technology in the carbon black production process, specifically a closed-loop water heat recovery device for a carbon black granulation and drying system. Background Technology

[0002] Carbon black is an important industrial raw material, widely used in industries such as rubber, plastics, and inks. In the production process of carbon black, wet granulation is a common post-processing method, which involves mixing powdered carbon black with water to form granules, followed by dehydration and drying in a dryer. During this process, the dryer typically uses hot air as the drying medium, and the exhaust gas is characterized by high temperature (typically 90℃-120℃) and near-saturated relative humidity, containing a large amount of water vapor and a small amount of entrained carbon black dust.

[0003] Currently, most companies treat carbon black drying exhaust gas by directly discharging it after cyclone dust removal or by simply spraying and washing it before emission. Both methods have several drawbacks. First, they result in significant energy waste. The large amount of sensible heat and latent heat of vaporization contained in the high-temperature, high-humidity exhaust gas is not recovered and utilized, leading to persistently high energy consumption in the drying system. Second, they waste water resources and easily generate secondary pollution. Spraying and washing requires a large amount of fresh water, and the resulting dust-laden wastewater requires additional treatment facilities, increasing operating costs. Third, they cause visual pollution. The emitted saturated wet flue gas condenses into white mist upon cooling, forming the "white smoke" phenomenon, which does not comply with increasingly stringent environmental emission standards. Summary of the Invention

[0004] To address the aforementioned problems, the present invention provides the following technical solution: a closed-loop hydrothermal recovery device for a carbon black granulation and drying system, characterized in that it comprises: a separator, with its inlet connected to the exhaust gas outlet of the dryer, for recovering carbon black from the exhaust gas; a condenser, with its inlet connected to the outlet of the separator, for cooling the exhaust gas to precipitate condensate and recovering heat therefrom; a circulation processing unit, comprising a demister, a circulating fan, and a heater; the inlet of the demister is connected to the outlet of the condenser, for removing droplets from the exhaust gas; the circulating fan is connected between the demister and the heater, and the outlet of the heater is connected to the inlet of the dryer, forming a closed-loop gas circulation; and a water treatment unit, with its inlet connected to the condensate outlet of the condenser, for collecting and purifying the condensate, with a portion of the purified water being returned to the condenser as a cooling water source.

[0005] Furthermore, the condensation recovery unit includes: a preheater, the hot side inlet of which is connected to the outlet of the separator, for recovering heat from the exhaust gas to preheat the fresh air entering the system; and a deep cooler, the inlet of which is connected to the hot side outlet of the preheater, for cooling the exhaust gas to below the dew point so that water vapor can be fully condensed.

[0006] Furthermore, the deep cooler is a spray tower, which is equipped with a spray head at the top and a water collection tray at the bottom; the spray head is connected to an external cooling water source for spraying cooling water and counter-current heat exchange with the exhaust gas.

[0007] Furthermore, the water treatment unit includes: a filter connected to the outlet of the water collection tray; a cooling tower connected to the outlet of the filter; and the outlet of the cooling tower is connected to the spray head via a water pump to form a spray cooling water circulation loop.

[0008] Furthermore, the heat source inlet of the heater is connected to the cold side outlet of the preheater to utilize the preheated fresh air; or steam / electric heating is used as an auxiliary heat source.

[0009] Furthermore, the separator is a cyclone separator or a cartridge separator, and an ash discharge valve is provided at its bottom.

[0010] Furthermore, the circulating fan is a variable frequency fan, used to adjust the circulating air volume.

[0011] Furthermore, nitrogen is introduced into the closed-loop gas circulation as a protective drying medium.

[0012] Furthermore, the deep cooler is a fluoroplastic tubular condenser.

[0013] Furthermore, it also includes an automatic control system that automatically adjusts the speed of the circulating fan, the power of the heater, and the water volume of the spray heads based on temperature, pressure, and humidity signals in the pipeline.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] By recovering the sensible heat of the exhaust gas through a preheater for preheating fresh air and recovering the latent heat of vaporization in the exhaust gas through a deep cooler, the overall energy consumption of the drying system can be significantly reduced. The water vapor in the exhaust gas is condensed and recovered, filtered and cooled, and then recycled as spray cooling water. The excess portion can be reused in the granulation process, achieving near-zero discharge and recycling of water resources. The closed-loop circulation design ensures that the drying medium is circulated within the system and no humid and hot exhaust gas is emitted to the outside, completely eliminating the "white smoke" phenomenon. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0017] Figure 1 This is a process flow diagram of a closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to the present invention.

[0018] In the diagram: 1. Dryer; 2. Cyclone separator; 3. Ash discharge valve; 4. Preheater; 5. Fresh air duct; 6. Spray tower; 7. Spray head; 8. Water collection tray; 9. Water pump; 10. Demister; 11. Circulating fan; 12. Heater; 13. Return air duct; 14. Filter; 15. Cooling tower. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown in the figure, the closed-loop hydrothermal recovery device of the carbon black granulation and drying system provided in this embodiment of the invention mainly includes a gas-solid separation section, a condensation heat recovery section, a gas circulation treatment section and a water treatment section.

[0021] A cyclone separator 2, acting as a separator, is connected to the exhaust gas outlet pipe of dryer 1. Cyclone separator 2 is a vertical cylindrical structure, with its upper tangential inlet connected to the exhaust gas outlet of dryer 1. An ash discharge valve 3 is installed at the bottom outlet of cyclone separator 2 to recover the separated carbon black particles to the finished product system.

[0022] The condenser recovery unit consists of a preheater 4 and a spray tower 6, which serves as a deep cooler, connected in series.

[0023] The gas outlet at the top of the cyclone separator 2 is connected to the hot-side inlet of the preheater 4 via a pipe. The preheater 4 is a shell-and-tube heat exchanger (such as a plate or tube type), and its cold-side inlet is connected to the fresh air duct 5 to draw in fresh outside air.

[0024] The outlet of the preheater 4 on the hot side is connected to the air inlet at the lower middle part of the spray tower 6 via a pipe. The spray tower 6 is a vertical cylindrical shape with spray heads 7 at the top and a water collection tray 8 at the bottom. The spray heads 7 are used to spray cooling water downwards, which comes into countercurrent contact with the hot exhaust gas entering from the bottom of the tower, allowing for sufficient heat and mass exchange, cooling the exhaust gas to below the dew point, and causing water vapor to condense into water droplets that fall into the water collection tray 8.

[0025] The air outlet at the top of the spray tower 6 is connected to the inlet of the demister 10 via a pipe. The demister 10 is a horizontal cylindrical shape with baffles or wire mesh inside to capture fine droplets entrained in the airflow.

[0026] The outlet of the demister 10 is connected to the inlet of the circulating fan 11 via a pipe. The circulating fan 11 is a variable frequency centrifugal fan used to provide power for gas circulation. The outlet of the circulating fan 11 is connected to the inlet of the heater 12 via a pipe. The heater 12 is equipped with heat exchange coils or fins, and its heating medium inlet can be selectively connected to the cold side outlet of the preheater 4 (using preheated fresh air) or external steam / power (as an auxiliary heat source).

[0027] The outlet of heater 12 is connected to the air inlet at the front end of dryer 1 through return air pipe 13, thereby forming a completely closed gas circulation loop that discharges from dryer 1, is purified and dehumidified, reheated and then returns to dryer 1.

[0028] The water collection tray 8 at the bottom of the spray tower 6 has an outlet, which is connected to the filter 14 via a pipe. The filter 14 is used to remove trace carbon black particles contained in the condensate. The outlet of the filter 14 is connected to the inlet of the cooling tower 15. The cooling tower 15 can be an open or closed cooling tower, used to reduce the temperature of the circulating water. The outlet of the cooling tower 15 is connected to the water pump 9 via a pipe, and the outlet of the water pump 9 is finally connected back to the spray head 7 at the top of the spray tower 6, forming an independent spray cooling water circulation loop.

[0029] To optimize operation, the device may also include an automatic control system. This system is equipped with temperature, pressure, and humidity sensors on key pipelines, and all sensor signals are fed back to a controller. Based on the difference between preset and measured values, the controller automatically adjusts the speed of the circulating fan 11 to control the circulating air volume, adjusts the power of the heater 12 to control the drying temperature, and adjusts the frequency converter of the water pump 9 to control the spray water volume, ensuring the system is always in optimal energy-saving operation.

[0030] Working principle:

[0031] The high-temperature and high-humidity exhaust gas (containing a small amount of carbon black) discharged from dryer 1 first enters cyclone separator 2, where most of the carbon black particles are separated. The separated exhaust gas then enters preheater 4, where it exchanges heat with cold air from fresh air duct 5, causing the exhaust gas temperature to decrease (sensible heat is recovered to preheat the fresh air). The preheated cold air can then be used as a heat source in heater 12 or directly for other purposes.

[0032] The initially cooled exhaust gas then enters the spray tower 6, where it comes into countercurrent contact with the low-temperature cooling water sprayed from the spray heads 7, and is deeply cooled to 30-40℃. Most of the water vapor in the exhaust gas condenses into water here and falls into the water collection tray 8. The condensate is filtered by the filter 14 to remove impurities, then cooled by the cooling tower 15, and finally pumped back to the spray heads 7 by the water pump 9 for reuse.

[0033] After the moisture is removed, the low-temperature saturated exhaust gas enters the demister 10 to remove entrained droplets, becoming a dry low-temperature gas. This gas is pressurized by the circulating fan 11 and sent to the heater 12 to be heated to the required drying temperature (e.g., 120-150℃). Finally, it is sent back to the dryer 1 through the return air duct 13 to be reused as a drying medium, completing the entire closed-loop cycle.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A closed-loop hydrothermal recovery device for a carbon black granulation and drying system, characterized in that, include: The separator is connected at the outlet of the dryer (1) to recover carbon black from the exhaust gas. A condenser recovery unit, with its inlet connected to the outlet of the separator, is used to cool the exhaust gas to condense water and recover heat from it. The circulating processing unit includes a demister (10), a circulating fan (11), and a heater (12); the inlet of the demister (10) is connected to the outlet of the condenser recovery unit to remove liquid droplets from the exhaust gas; the circulating fan (11) is connected between the demister (10) and the heater (12), and the outlet of the heater (12) is connected to the inlet of the dryer (1) to form a closed-loop gas circulation; The water treatment unit has its inlet connected to the condensate outlet of the condensate recovery unit, which is used to collect and purify the condensate. Part of the purified water is then returned to the condensate recovery unit as a cooling water source.

2. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 1, characterized in that: The preheater (4), whose hot-side inlet is connected to the outlet of the separator, is used to recover the heat of the exhaust gas to preheat the fresh air entering the system; The deep cooler (6), whose inlet is connected to the outlet of the hot side of the preheater (4), is used to cool the exhaust gas below the dew point so that the water vapor can be fully condensed.

3. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 2, characterized in that: The deep cooler (6) is a spray tower with a spray head (7) at the top and a water collection tray (8) at the bottom; the spray head (7) is connected to an external cooling water source for spraying cooling water and counter-current heat exchange with the exhaust gas.

4. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 3, characterized in that: A filter (14) connected to the outlet of the water collection tray (8); Cooling tower (15) connected to the outlet of filter (14); The outlet of the cooling tower (15) is connected to the spray head (7) via a water pump (9) to form a spray cooling water circulation loop.

5. A closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 2, characterized in that: The heat source inlet of the heater (12) is connected to the cold side outlet of the preheater (4) for utilizing the preheated fresh air; or steam / electric heating is used as an auxiliary heat source.

6. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 1, characterized in that: The separator is a cyclone separator (2) or a cartridge separator, and its bottom is equipped with an ash discharge valve (3).

7. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 1, characterized in that: The circulating fan (11) is a variable frequency fan used to adjust the circulating air volume.

8. The closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 1, characterized in that: Nitrogen gas is introduced into the closed-loop gas circulation system as a protective drying medium.

9. A closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claim 2, characterized in that: The deep cooler (6) is a fluoroplastic tubular condenser.

10. A closed-loop hydrothermal recovery device for a carbon black granulation and drying system according to claims 1 to 9, characterized in that: It also includes an automatic control system that automatically adjusts the speed of the circulating fan (11), the power of the heater (12), and the water volume of the spray head (7) based on the temperature, pressure, and humidity signals in the pipeline.

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