Pre-drying system for recycling PHA flash evaporation tail gas

Abstract

The utility model discloses a pre-drying system for recycling PHA flash tail gas, which is characterized in that a crusher is connected with a chain conveyor, the chain conveyor is connected with a flash dryer through a screw feeder, the flash dryer is sequentially connected with a cyclone separator, a bag-type dust collector and an induced draft fan, and the induced draft fan is connected with a water film dust collector through an air heat exchanger. Heat of flash tail gas is exchanged with fresh air through the air heat exchanger, PHA materials are pre-dried in the chain conveyor, the drying efficiency of the materials is improved, and heat waste is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of flash drying, and particularly relates to a pre-drying system for recycling and reusing the flash evaporation tail gas of PHA. Background Technique

[0002] A flash dryer is a new type of continuous drying equipment that integrates drying, pulverizing, and screening. It is particularly suitable for drying filter cake-like, paste-like, and thin slurry-like materials. Specifically, the materials are pulverized inside the equipment, fully contact with hot air, are heated and dried. The dehydrated dry materials rise with the hot air flow. The grading ring intercepts large particles, and small particles are discharged outside the dryer and recovered. The undried or large pieces of materials are thrown towards the wall of the dryer by centrifugal force and fall back to the bottom to be pulverized and dried again. The dried materials are carried by the air flow into the dust collection system for collection and treatment. After meeting the environmental protection requirements, the tail gas is exhausted, and the entire drying process is completed. Therefore, the flash dryer can dry the materials into uniform powder products at one time, omitting processes such as pulverizing and screening, and the final moisture content of the material fineness can be adjusted, improving the drying uniformity. However, when the flash dryer works, the inlet air temperature is 170 - 180 °C, and the tail gas emission temperature is 65 - 70 °C. Although it meets the tail gas emission standards, there is a large amount of waste of heat energy.

[0003] Chinese Patent CN215002560U discloses a flash drying system for waste heat recovery, including a control system and a waste heat recovery heater, a filtering device, a blower, a heat dissipation device, a flash dryer, a cyclone dryer, a bag filter, and an induced draft fan connected in sequence; the air outlet of the induced draft fan is connected to the waste heat recovery heater, and the control system is connected to each component. The utility model has a large drying intensity, and recycles and reuses the tail gas twice, which can save a large amount of costs and improve the drying efficiency.

[0004] Chinese Patent CN106197001A discloses a tail gas circulation application system for a flash dryer, mainly including an induced draft fan, a spray dehumidification tower, a water collection tank, a cooler, a circulation pump, and a blower. It establishes a moisture balance, a heat balance, and a system pressure balance, and uses a dust collector and a spray dehumidification device to fully treat the high-temperature, dust-containing, and moisture-containing tail gas from the flash dryer, so that the dust content in the treated tail gas is extremely low, the odor in the tail gas is eliminated, and there is no waste gas emission, having excellent environmental benefits; the treated flash dryer tail gas and the spray water in the spray dehumidification tower are recycled, realizing the recycling of substances and energy, and solving the problems of high temperature, moisture, dust, odor, and difficult recycling of the flash dryer tail gas.

[0005] However, in the prior art, for the tail gas generated during the flash drying process, generally, a waste heat recovery heater is used for heat recovery, or it is recycled after cooling, dehumidifying, and re-dusting treatment. There is often still a certain amount of heat waste, and the use method of the recovered heat is not clear. In addition, before the PHA material is dried using a flash dryer, it needs to be transported through a long belt, which is easily affected by external factors, has a long transportation time, and low efficiency. Therefore, it is considered to design a system that can pre-dry the PHA material during the transportation process, improve the drying efficiency of the material, and avoid the PHA material being affected by external factors. Summary of the Invention

[0006] In view of the above technical problems, the present utility model provides a pre-drying system for recycling and reusing PHA flash tail gas, which exchanges the heat of the flash tail gas with fresh air through an air heat exchanger, pre-dries the PHA material in a chain conveyor, improves the drying efficiency of the material, and reduces heat waste.

[0007] To achieve the above object, the present utility model provides a pre-drying system for recycling and reusing PHA flash tail gas. A crusher is connected to a chain conveyor, the chain conveyor is connected to a flash dryer through a screw feeder, the flash dryer is sequentially connected to a cyclone separator, a bag filter, and an induced draft fan, and the induced draft fan is connected to a water film dust collector through an air heat exchanger.

[0008] Preferably, the water film dust collector is connected to a blower, and the blower is connected to the flash dryer.

[0009] Preferably, one end of the air heat exchanger is connected to a fresh air blower, the other end is connected to the chain conveyor, and the chain conveyor is connected to the bag filter through a pipeline.

[0010] Further preferably, the chain conveyor includes a chain conveyor belt, a conveyor belt, and a sealed housing.

[0011] Preferably, the cyclone separator and the bag filter are connected to a receiving truck through a pipeline.

[0012] The beneficial effects of the present utility model are as follows: The air heat exchanger is used to exchange heat between the flash tail gas and fresh air. The fresh air is heated to 55 - 65°C by the flash tail gas at 60 - 70°C, and then the heated fresh air after heat exchange is transported into the chain conveyor to pre-dry the crushed PHA material, removing about 50% of the moisture in the material first, reducing the pressure on the flash dryer, improving the drying efficiency, and reducing heat waste. Brief Description of the Drawings

[0013] Figure 1This is the overall structural schematic diagram of the present utility model. In the figure, 1 is a fresh air blower, 2 is an air heat exchanger, 3 is a chain conveyor, 4 is a crusher, 5 is a blower, 6 is a flash dryer, 7 is a cyclone separator, 8 is a bag filter, 9 is an induced draft fan, 10 is a water film dust collector, 11 is a screw feeder, 12 is a receiving truck, 13 is a chain conveyor belt, 14 is a conveyor belt, and 15 is a sealed housing. Detailed implementation manners

[0014] The technical solution of the present utility model will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only the preferred embodiments of the present utility model and should not be construed as a limitation to the present utility model. The protection scope of the present utility model shall be subject to the content recorded in the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present utility model without creative work shall fall within the protection scope of the present utility model.

[0015] Embodiment 1

[0016] A pre-drying system for recycling PHA flash tail gas. The crusher 4 is connected to the chain conveyor 3 to first crush the PHA material obtained by pressure filtration and then transmit it. The chain conveyor 3 is connected to the flash dryer 6 via a screw feeder. The flash dryer 6 is sequentially connected to the cyclone separator 7, the bag filter 8, and the induced draft fan 9. The induced draft fan 9 is connected to the water film dust collector 10 via the air heat exchanger 2 to perform flash drying on the PHA material. After drying, most of the materials are centrally collected at the bottom of the cyclone separator 7 and then collected and transported by the receiving truck 12. A small part of the materials are intercepted and powdered by the bag filter 8 and then collected and transported by the receiving truck. The generated flash tail gas is led out by the induced draft fan 9, exchanges heat with fresh air in the air heat exchanger 2, and then enters the water film dust collector 10 for further dust removal and humidity reduction.

[0017] Preferably, the water film dust collector 10 is connected to the blower 5, and the blower 5 is connected to the flash dryer 6 to send the flash tail gas after dust removal and humidity reduction into the flash dryer 6 again via the blower for recycling.

[0018] Preferably, one end of the air heat exchanger 2 is connected to the fresh air blower 1, and the other end is connected to the chain conveyor 3. The chain conveyor 3 is connected to the bag filter 8 through a pipeline. The fresh air sent by the fresh air blower 1 exchanges heat with the flash gas in the air heat exchanger 2, is heated to 55 - 65 °C and then enters the chain conveyor 3 to pre-dry the crushed PHA material, taking away 50% of the moisture of the PHA material, reducing the drying pressure of the flash dryer 6, and at the same time improving the drying efficiency and heat utilization efficiency.

[0019] Further preferably, the chain conveyor 3 includes a chain conveyor belt 13, a conveyor belt 14 and a sealed housing 15. The chain conveyor belt 13 is composed of chains with certain gaps through which air can pass. The fresh air after heat exchange and temperature rise enters from the bottom of the chains and is discharged from the top, increasing the contact area between the material and the fresh air and accelerating the evaporation of moisture in the material. The conveyor belt is made of rubber and runs in the same direction as the chain conveyor belt. It collects the fine materials that fall through the gaps of the chain conveyor belt and conveys them to the screw feeder, and then enters the flash dryer 6 together for processing, avoiding waste of materials. The sealed housing isolates the PHA material from the outside world and at the same time prevents flying powder from being generated during the pre-drying process, reducing the impact on the environment.

[0020] Even more preferably, the fresh air after heat exchange and temperature rise enters from the end position at the bottom of the chain conveyor 3, and then is mainly discharged from the position near the crusher 1 at the top, and a small part is discharged from the end position at the top, making the movement direction of the fresh air opposite to that of the PHA material. While overall pre-drying the PHA material, the chain conveyor 3 is processed, improving the overall drying efficiency.

[0021] Preferably, the cyclone separator 7 and the bag filter 8 are connected to the receiving truck 12 through pipelines to collect the dried PHA material and then transfer it centrally.

Claims

1. A pre-drying system for recycling and reusing the flash tail gas of PHA, characterized in that: The crusher (4) is connected to the chain conveyor (3), and the chain conveyor (3) is connected to the flash dryer (6) via a screw feeder. The flash dryer (6) is successively connected to a cyclone separator (7), a bag filter (8), and a draft fan (9). The draft fan (9) is connected to a water film dust collector (10) via an air heat exchanger (2).

2. The pre-drying system for recycling PHA flash tail gas according to claim 1, characterized in that: The water film dust collector (10) is connected to a blower (5), and the blower (5) is connected to the flash dryer (6).

3. The pre-drying system for recycling the flash tail gas of PHA according to claim 1, wherein: One end of the air heat exchanger (2) is connected to a fresh air blower (1), and the other end is connected to the chain conveyor (3). The chain conveyor (3) is connected to the bag filter (8) by a pipeline.

4. The pre-drying system for recycling and reusing the PHA flash tail gas according to claim 1 or 3, characterized in that: The chain conveyor (3) includes a chain conveyor belt (13), a conveyor belt (14), and a sealed housing (15).

5. The pre-drying system for recycling the flash tail gas of PHA according to claim 1, wherein: The cyclone separator (7) and the bag filter (8) are connected to a receiving truck (12) by a pipeline.

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