A heat pump-based spray drying system waste heat recovery coupled tail gas treatment system

Abstract

The utility model discloses a kind of spray drying system waste heat recovery coupling tail gas processing systems based on heat pump, including composite heat pump unit, the first inlet of composite heat pump unit is connected with normal temperature air pipeline intercommunication;Heat exchanger, the inlet of heat exchanger is connected with the first outlet of composite heat pump unit intercommunication;Spray drying tower, the inlet of spray drying tower is connected with the outlet of heat exchanger intercommunication;Dust remover, the inlet of dust remover is connected with the outlet of spray drying tower intercommunication, the outlet of dust remover is connected with the second inlet of composite heat pump unit intercommunication;Washing tower, the inlet of washing tower is connected with the second outlet of composite heat pump unit intercommunication.The utility model utilizes composite heat pump unit to spray drying tail gas first cooling condensation, then carries out washing absorption, using first condensation recovery, absorption purification secondary tail gas processing new process after, realize the removal of pollution classifying, high efficiency, low cost.

Description

Technical Field

[0001] This utility model relates to the field of industrial energy conservation and environmental protection technology, and in particular to a waste heat recovery coupled tail gas treatment system based on a heat pump spray drying system. Background Technology

[0002] Spray drying technology is widely used in industries such as chemical, food, and pharmaceutical to dry solutions, suspensions, or slurries into powdered products. This process requires a large amount of heat energy to heat room temperature air to a high temperature. The solids are then collected as the product using dust removal facilities (bag filters, cyclones, etc.). At the same time, it generates a large amount of high-temperature, high-humidity exhaust gas containing dust and volatile organic compounds (VOCs).

[0003] Traditional spray drying systems have two major problems: (i) High energy consumption: Traditional systems directly discharge high-temperature and high-humidity exhaust gas or discharge it after simple treatment. The discharged exhaust gas carries a large amount of latent heat and sensible heat, which is difficult to thermally couple. The energy is directly discharged into the air and is wasted. As a result, the drying process requires a continuous input of a large amount of fresh heat energy, resulting in high operating costs.

[0004] (ii) High pollution treatment costs: The exhaust gas downstream of dust removal facilities contains some dust and VOCs, which usually require separate subsequent purification equipment (such as RTO incinerators, scrubbing towers, etc.) for treatment. Traditional methods mainly include "dust removal followed by incineration" and "single scrubbing" treatment methods, but both of these methods have drawbacks: if incineration is used, a large amount of fuel is required to reheat the exhaust gas, resulting in secondary energy consumption, and the gas volume is too large, resulting in large equipment investment and high operating energy consumption; if a scrubbing tower is used, the sensible heat and latent heat in the exhaust gas lead to high water consumption. At the same time, the protein dust in the exhaust gas is easy to stick to the packing or internal parts of the water scrubbing tower, and it is easy to ferment and produce odors in a high humidity environment, requiring a large amount of water for replacement. Moreover, the treatment effect on VOCs that are insoluble in water is poor, and the efficiency is low and the operating cost is high when treating exhaust gas with high humidity and large air volume.

[0005] In existing technologies, although there are methods to recover part of the waste heat using heat exchangers, they often only recover sensible heat and have poor effects on recovering latent heat. Furthermore, the exhaust gas treatment system and the drying system are independent of each other, failing to achieve the cascade utilization of energy and the synergistic and efficient removal of pollutants. Utility Model Content

[0006] To address the aforementioned problems, this invention provides a waste heat recovery coupled with exhaust gas treatment system based on a heat pump spray drying system, thereby solving the problems of high energy consumption, low processing efficiency, and high cost of existing spray drying systems.

[0007] This utility model is implemented as follows: A waste heat recovery coupled exhaust gas treatment system for a heat pump-based spray drying system includes: A composite heat pump unit, wherein the first inlet of the composite heat pump unit is connected to a normal temperature air pipeline; A heat exchanger, wherein the inlet of the heat exchanger is connected to the first outlet of the composite heat pump unit; A spray drying tower, wherein the inlet of the spray drying tower is connected to the outlet of the heat exchanger; A dust collector, the inlet of which is connected to the outlet of the spray drying tower, and the outlet of which is connected to the second inlet of the composite heat pump unit; A scrubbing tower, the inlet of which is connected to the second outlet of the composite heat pump unit.

[0008] Furthermore, the heat exchanger is connected to the composite heat pump unit via a first pipeline, and a first fan is installed on the first pipeline.

[0009] Furthermore, the dust collector is connected to the composite heat pump unit via a second pipeline, and a second fan is installed on the second pipeline.

[0010] Furthermore, the top of the washing tower is connected to an absorbent input pipeline, and the bottom of the washing tower is connected to an absorbent output pipeline.

[0011] Furthermore, the middle part of the washing tower is connected to an absorption liquid circulation pipeline, and a circulation pump is installed on the absorption liquid circulation pipeline.

[0012] Furthermore, the upper end of the absorbent circulation pipeline extends into the interior of the washing tower, and multiple nozzles are provided on the absorbent circulation pipeline located inside the washing tower.

[0013] Furthermore, the top of the scrubbing tower is also connected to an exhaust gas output pipeline, and a third fan is installed on the exhaust gas output pipeline.

[0014] Furthermore, a heating pipe is connected to the top of the heat exchanger, and a low-heat output pipe is connected to the bottom of the heat exchanger.

[0015] Furthermore, a material input pipeline is connected to the top of the spray drying tower, and a material output pipeline is connected to the bottom of the spray drying tower.

[0016] The beneficial effects of this utility model are: (1) Significant energy saving effect: Taking steam as an example of heat medium, without using a composite heat pump unit, the ambient air temperature is 15℃ and the air volume is 120,000 Nm³. 3The initial steam temperature after heat exchange is 160℃, consuming 12t / h of steam. When using a combined heat pump unit, the temperature can be preheated to 110℃, consuming 5t / h of steam and saving 7t / h of steam. This can save 55-60% of energy.

[0017] (2) Extremely high exhaust gas treatment efficiency: VOCs detection value at the outlet of the spray drying tower bag filter is 50 mg / m³. 3 When only the scrubbing method is used to treat the exhaust gas, the absorbent consumption is 60 kg / h, the exhaust gas temperature is 45℃, and the VOCs detection value is 20 mg / m³. 3 When using a composite heat pump unit, the VOCs detection value in low-temperature dry air is 15 mg / m³. 3 Absorbent consumption: 20 kg / h; exhaust gas temperature: 35℃; VOC detection value: 5 mg / m³ 3 The two-stage synergistic process of "condensation and absorption" can achieve a total VOCs removal efficiency of 85-90%, far exceeding that of single treatment methods (usually 50%-65%).

[0018] (3) Outstanding economic benefits: Based on 8,000 hours of operation per year, it saves 56,000 tons of steam per year. At RMB 120 / ton, the electricity consumption increases by 420 kW. At RMB 0.6 / kWh, it saves 320 tons of absorbent per year. At RMB 1,000 / ton, the total annual savings are RMB 672 + 32 - 201 = RMB 5.03 million.

[0019] (4) Stable system operation: The composite heat pump unit operates smoothly and has a high degree of automation, which reduces system fluctuations; the gas at the inlet of the scrubbing tower is cooled and dehumidified, and the operating conditions are stable, avoiding corrosion and impact on the packing and equipment inside the tower due to high temperature and high humidity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model.

[0021] Explanation of reference numerals in the attached figures: 1. Composite heat pump unit; 11. Ambient temperature air pipeline; 12. First pipeline; 13. Second pipeline; 14. Third pipeline; 2. Heat exchanger; 21. Heating pipeline; 22. Low heat output pipeline; 3. Spray drying tower; 31. Material input pipeline; 32. Material output pipeline; 4. Dust collector; 41. Discharge port; 5. Scrubber; 51. Absorbent input pipeline; 52. Absorbent liquid output pipeline; 53. Absorbent liquid circulation pipeline; 54. Circulation pump; 55. Tail gas output pipeline; 6. First fan; 7. Second fan; 8. Third fan. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Many specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] like Figure 1 The diagram shows a waste heat recovery coupled tail gas treatment system for a heat pump-based spray drying system according to this invention. It includes a composite heat pump unit 1, a heat exchanger 2, a spray drying tower 3, a dust collector 4, and a scrubbing tower 5. The first inlet of the composite heat pump unit 1 is connected to a normal temperature air pipeline 11; the inlet of the heat exchanger 2 is connected to the first outlet of the composite heat pump unit 1; the inlet of the spray drying tower 3 is connected to the outlet of the heat exchanger 2; the inlet of the dust collector 4 is connected to the outlet of the spray drying tower 3; the outlet of the dust collector 4 is connected to the second inlet of the composite heat pump unit 1; and the inlet of the scrubbing tower 5 is connected to the second outlet of the composite heat pump unit 1 via a third pipeline 14.

[0024] The composite heat pump unit 1 is placed between the dust collector 4 and the scrubbing tower 5, enabling it to perform the dual functions of a "waste heat recovery unit" and a "tail gas pretreatment condenser". In this embodiment, steam is used as the heat medium. Without the composite heat pump unit 1, the ambient air temperature is 15°C and the air volume is 120,000 Nm³. 3 The heat exchanged air temperature is 160℃, consuming 12t / h of steam. When using the composite heat pump unit 1, the temperature can be preheated to 110℃, consuming 5t / h of steam, saving 7t / h of steam, and achieving energy savings of 55-60%.

[0025] The heat exchanger 2 is connected to the composite heat pump unit 1 via a first pipeline 12, on which a first fan 6 is installed. Room temperature air enters the composite heat pump unit 1 through the room temperature air pipeline 11, and is heated to become medium temperature air. The medium temperature air is then transported to the heat exchanger 2 by the power of the first fan 6 in the first pipeline 12, and is heated to become high temperature air after passing through the heat exchanger 2.

[0026] The top of the heat exchanger 2 is connected to a heating pipe 21, which is connected to a heat source and is used to supply a high-heat medium to the heat exchanger 2. The bottom of the heat exchanger 2 is connected to a low-heat output pipe 22, which is used to discharge a low-temperature medium.

[0027] The top of the spray drying tower 3 is connected to a material inlet pipe 31, which is used to convey wet material into the spray drying tower 3. The bottom of the spray drying tower 3 is connected to a material outlet pipe 32. After drying, the wet material in the spray drying tower 3 becomes dry material, which is discharged from the material outlet pipe 32. The bottom of the dust collector 4 is connected to a discharge port 41. The dust collected by the dust collector 4 falls to its bottom and is discharged from the discharge port 41.

[0028] This embodiment conducted an experiment where the VOCs detection value at the outlet of spray drying tower 3 and dust collector 4 was 50 mg / m³. 3 When only the scrubbing method is used to treat the exhaust gas, the absorbent consumption is 60 kg / h, the exhaust gas temperature is 45℃, and the VOCs detection value is 20 mg / m³. 3 When using the composite heat pump unit 1, the VOCs detection value in the low-temperature dry air is 15 mg / m³. 3 Absorbent consumption: 20 kg / h; exhaust gas temperature: 35℃; VOCs detection value: 5 mg / m³ 3 The two-stage synergistic process of "condensation and absorption" can achieve a total VOCs removal efficiency of 85-90%, far exceeding that of single treatment methods (usually 50%-65%).

[0029] The dust collector 4 is connected to the combined heat pump unit 1 via a second pipe 13, on which a second fan 7 is installed. The inlet of the scrubbing tower 5 is connected to the second outlet of the combined heat pump unit 1 via a third pipe 14. An absorbent input pipe 51 is connected to the top of the scrubbing tower 5, used to replenish and transport absorbent into the scrubbing tower 5. An absorbent liquid output pipe 52 is connected to the bottom of the scrubbing tower 5, used to periodically discharge the absorbent to prevent saturation. An absorbent liquid circulation pipe 53 is connected to the middle of the scrubbing tower 5, on which a circulation pump 54 is installed, continuously circulating the absorbent. The upper end of the absorbent liquid circulation pipe 53 extends into the scrubbing tower 5, and multiple nozzles are installed on the absorbent liquid circulation pipe 53 located inside the scrubbing tower 5. The top of the scrubbing tower 5 is also connected to an exhaust gas output pipe 55, which is used to output the purified exhaust gas. A third fan 8 is installed on the exhaust gas output pipe 55. The purified exhaust gas is discharged to the outside of the scrubbing tower 5 through the third fan 8, or re-enters the system as ambient temperature air.

[0030] The working process of the waste heat recovery coupled tail gas treatment system of the spray drying system based on the heat pump of this utility model is as follows: 1. Room temperature air enters the composite heat pump unit 1 through room temperature air pipe 11, and after passing through the composite heat pump unit 1, it is heated to obtain medium temperature air.

[0031] 2. Medium-temperature air is transported to heat exchanger 2 by the power of the first fan 6 on the first pipeline 12, and the air is heated by the heat exchanger 2 to obtain high-temperature air.

[0032] 3. The heat source of heat exchanger 2 is a high-heat medium. The high-heat medium is transported to heat exchanger 2 through heating pipeline 21. After the heat is utilized, the low-temperature medium is discharged through low-heat output pipeline 22.

[0033] 4. Inside the spray drying tower 3, wet material is transported into the spray drying tower 3 through the material input pipe 31. High-temperature air enters the spray drying tower 3 and carries away the moisture from the wet material, forming dust-laden hot and humid air, and dry material is obtained. The dry material is discharged from the material output pipe 32. The wet material contains moisture and volatile substances. After drying, the moisture and volatile substances enter the dust-laden hot and humid air. During the natural fall of the dry material, some fine dust particles enter the dust-laden hot and humid air, which then enters the dust collector 4 through the pipe.

[0034] 5. After passing through the dust collector 4, the dust-laden hot and humid air becomes clean hot and humid air and dust. The clean hot and humid air is then transported to the second inlet of the composite heat pump unit 1 via the second pipeline 13 and the second fan 7. Upon entering the composite heat pump unit 1, it is cooled to obtain low-temperature dry air, which then enters the scrubbing tower 5 via the third pipeline 14. During the cooling process, moisture and most volatile substances in the clean hot and humid air enter the condensate.

[0035] 6. Low-temperature dry air enters the scrubbing tower 5 through the third pipeline 14. After scrubbing, purified exhaust gas is obtained. Inside the scrubbing tower 5, absorbent is replenished and transported through the absorbent input pipeline 51. After the absorbent absorbs the volatile substances remaining in the low-temperature dry air, it forms an absorbent liquid. The absorbent liquid continuously flows into the scrubbing tower 5 through the circulation pump 54 on the absorbent liquid circulation pipeline 53. To prevent the absorbent liquid from becoming saturated, the absorbent liquid is periodically discharged through the absorbent liquid output pipeline 52 and sent to the sewage treatment system for treatment. The purified exhaust gas is discharged to the outside through the third fan 8 on the exhaust gas output pipeline 55, or it can be reused as ambient temperature air in the system, thus achieving recycling.

[0036] The composite heat pump unit 1 first cools and condenses the spray-dried exhaust gas, and then washes and absorbs it. Specifically, the new two-stage exhaust gas treatment process of "first condensation and recovery (dehumidification + removal of most VOCs), then absorption and purification (removal of residual VOCs)" achieves graded, efficient, and low-cost removal of pollutants, and has good economic benefits: based on 8,000 hours of operation per year, it saves 56,000 tons of steam per year, calculated at 120 yuan / ton, and increases electricity consumption by 420 kW, calculated at 0.6 yuan / kWh; it saves 320 tons of absorbent per year, calculated at 1,000 yuan / ton, for a total annual saving of 672 + 32 - 201 = 5.03 million yuan.

[0037] While this utility model discloses preferred embodiments to achieve the above objectives, it is not intended to limit the structural features of this utility model. Anyone skilled in the art should know that any easily conceivable variations or modifications are possible under the technical spirit of this utility model and are covered by the patent claims of this utility model.

Claims

1. A waste heat recovery coupled tail gas treatment system for a heat pump-based spray drying system, characterized in that, include: The first inlet of the composite heat pump unit (1) is connected to the ambient air pipeline (11); Heat exchanger (2), the inlet of which is connected to the first outlet of the composite heat pump unit (1); The spray drying tower (3) has its inlet connected to the outlet of the heat exchanger (2); Dust collector (4), the inlet of the dust collector (4) is connected to the outlet of the spray drying tower (3), and the outlet of the dust collector (4) is connected to the second inlet of the composite heat pump unit (1); The inlet of the washing tower (5) is connected to the second outlet of the composite heat pump unit (1).

2. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 1, wherein, The heat exchanger (2) is connected to the composite heat pump unit (1) through a first pipeline (12), and a first fan (6) is provided on the first pipeline (12).

3. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 2, wherein, The dust collector (4) is connected to the composite heat pump unit (1) through a second pipeline (13), and a second fan (7) is provided on the second pipeline (13).

4. The heat pump based spray drying system waste heat recovery coupled off-gas treatment system of claim 2 or 3, wherein, The top of the washing tower (5) is connected to an absorbent inlet pipe (51), and the bottom of the washing tower (5) is connected to an absorbent outlet pipe (52).

5. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 4, wherein, The middle part of the washing tower (5) is connected to an absorption liquid circulation pipeline (53), and a circulation pump (54) is provided on the absorption liquid circulation pipeline (53).

6. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 5, wherein, The upper end of the absorbent circulation pipeline (53) extends into the washing tower (5), and multiple nozzles are provided on the absorbent circulation pipeline (53) located inside the washing tower (5).

7. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 4, wherein, The top of the scrubbing tower (5) is also connected to a tail gas output pipe (55), and a third fan (8) is provided on the tail gas output pipe (55).

8. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 1, wherein, The top of the heat exchanger (2) is connected to a heating pipe (21), and the bottom of the heat exchanger (2) is connected to a low heat output pipe (22).

9. The heat pump based spray drying system waste heat recovery coupled tail gas treatment system of claim 1, wherein, The top of the spray drying tower (3) is connected to a material input pipe (31), and the bottom of the spray drying tower (3) is connected to a material output pipe (32).

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