Liquid drying and solid drying combined process and device for malic acid

Abstract

A liquid drying and solid drying ring drying combined process and device for malic acid are characterized in that a crawler belt, a heating flat plate and a distributing gun are mounted in an inner cavity of a belt type vacuum liquid drying machine, a discharge port of the belt type vacuum liquid drying machine is communicated with a feed port of a spiral drying machine, and a heating jacket is mounted on a shell of the spiral drying machine; a rotating shaft and a spiral blade are arranged in an inner cavity of the spiral drying machine, discharging of the raw material tank is connected with a material distributing gun through a screw pump and a feeding pipeline, and a vapor phase pipeline of the belt type vacuum liquid drying machine is connected with a condenser and a vacuum unit. Malic acid slurry is rapidly dried into blocky solids with the water content of 5% through a belt type vacuum liquid drying machine, and then the blocky solids are conveyed to a spiral drying machine to be crushed, turned over and dried till the water content is 1t; and 0.5% of the product is obtained. According to the invention, the respective advantages of the two devices are exerted, the productivity is greatly improved, the investment is saved for the large-scale production of enterprises, and the benefits are improved.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a combined process and apparatus for liquid and solid drying of malic acid. Background Technology

[0002] Industrially, malic acid is mainly produced through natural fermentation and chemical synthesis. Regardless of the method, the final product is a liquid slurry containing both water and malic acid. To obtain a dry malic acid product, a drying device is necessary. Commonly used drying methods include fluidized bed drying and belt vacuum liquid dryers. Fluidized bed drying suffers from high energy consumption, while belt vacuum liquid dryers have low production capacity. In-depth research on belt vacuum liquid dryers reveals that during the drying process, the drying efficiency is high when the moisture content decreases from 20% to 5%. However, the drying efficiency drops significantly from 5% to 0.5%. This is because after most of the water evaporates, the aqueous phase is no longer a continuous phase, and heat transfer relies solely on solid-state conduction. However, the material is stationary on the conveyor belt, lacking any agitation, resulting in poor heat transfer and ultimately, unsatisfactory drying performance and low production capacity. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the problems existing in the prior art and provide a combined liquid drying and solid drying process and apparatus for malic acid, which leverages the advantages of both liquid drying equipment and solid drying equipment, overcomes their respective disadvantages, greatly increases production capacity, saves investment for large-scale production, improves efficiency, and enables continuous drying of malic acid with good results, reducing the moisture content from 20% to 0.5%, and rapidly improving product quality and pass rate.

[0004] The technical solution adopted in this invention is: a combined liquid and solid drying device for malic acid, comprising a belt vacuum liquid dryer and a spiral dryer. The inner cavity of the belt vacuum liquid dryer is equipped with a heating plate on the inner side of the covering belt and the conveyor belt, as well as a feeding gun for the material on the covering belt. The discharge port of the belt vacuum liquid dryer is connected to the inlet of the spiral dryer. The spiral dryer shell is equipped with a heating jacket. The inner cavity of the spiral dryer is equipped with a rotating shaft and spiral blades on the rotating shaft. The rotating shaft is driven by a motor at one end of the spiral dryer. The discharge port of the spiral dryer is connected to a discharge tank. The discharge end of the raw material tank is connected to the feeding gun inside the belt vacuum liquid dryer through a screw pump and a feeding pipe. The vapor phase pipe of the belt vacuum liquid dryer is connected to a condenser, and the condenser is then connected to a vacuum unit.

[0005] In the above technical solution, there are multiple tracks, multiple heating plates on the inner side of the tracks, and multiple corresponding cloth-laying guns. Each cloth-laying gun is supplied with raw materials by a screw pump. Thus, there are also multiple screw pumps, and all of the multiple screw pumps are supplied with raw materials from the same raw material tank.

[0006] In the above technical solution, the discharge tank includes a primary discharge tank and a secondary discharge tank. The primary discharge tank is connected to the discharge port of the spiral dryer. The bottom outlet of the primary discharge tank is connected to the inlet of the secondary discharge tank through an intermediate pneumatic valve. The discharge end of the secondary discharge tank is connected to a discharge pneumatic valve.

[0007] In the above technical solution, the condenser is filled with chilled water and has a chilled water inlet and a chilled water outlet. The condensate outlet pipe at the bottom of the condenser is connected to a condensate collection tank, and the exhaust gas pipe of the condenser is connected to a vacuum unit.

[0008] In the above technical solution, the belt vacuum liquid dryer has a heat source inlet and a drain valve. The heat source inlet is connected to the inlet end of the heating plate, and the outlet end of the heating plate is connected to the drain valve.

[0009] In the above technical solution, the heating jacket of the spiral dryer has a heat source inlet and a heat source outlet.

[0010] In the above technical solution, the heat source is hot water, steam, or heat transfer oil.

[0011] In the above technical solution, the pneumatic valve may be an electric valve.

[0012] A combined process for liquid drying and solid drying based on the above-mentioned malic acid combined apparatus includes: (1) The vacuum unit evacuates the belt vacuum liquid dryer through the exhaust gas pipe, condenser and vapor phase pipe; (2) The material from the raw material tank is fed into the cloth gun in the belt vacuum liquid dryer through the screw pump and the feed pipe; (3) The cloth gun evenly distributes the raw material onto the conveyor belt inside the belt vacuum liquid dryer, and the conveyor belt moves forward slowly; (4) The malic acid liquid raw material on the track is heated by the heating plate inside the track, the water or solvent is evaporated, and the raw material is dried. (5) When the raw material is dried to a certain moisture content on the belt of the belt vacuum liquid dryer, it enters the feed port of the screw dryer from the discharge port of the belt vacuum liquid dryer. The raw material is pushed forward by the spiral blades inside the screw dryer while being turned over. During the turning and moving forward process, the raw material is heated and further dried by the heating jacket on the casing of the screw dryer. (6) After the raw materials are dried into qualified products in the spiral dryer, they enter the primary discharge tank and the secondary feed tank from the spiral dryer outlet. (7) When it is necessary to discharge the product from the secondary discharge tank, first close the intermediate pneumatic valve, open the discharge pneumatic valve, and discharge the product from the secondary discharge tank. (8) Then close the discharge pneumatic valve and open the intermediate pneumatic valve so that the secondary discharge tank can continue to receive products.

[0013] In the above technical solution, in step (5), the raw material is dried on the track to a certain moisture content of 5%.

[0014] In the above technical solution, in step (6), the raw material is dried in the screw dryer to become a qualified product with a moisture content of <0.5%.

[0015] This invention addresses the problem in existing industrial malic acid production where drying efficiency is high when the moisture content decreases from 20% to 5%, but drops drastically when decreasing from 5% to 0.5%. The invention provides a combined liquid and solid drying process and apparatus for malic acid. First, a belt vacuum liquid dryer is used to dry the malic acid slurry from 20% moisture content to 5% moisture content, at which point the material is solid. Then, the solid raw material is fed into a vacuum spiral dryer for further drying by turning. This combination leverages the advantages of each piece of equipment while overcoming their respective disadvantages, significantly increasing production capacity, saving investment for large-scale production, and improving efficiency.

[0016] The belt vacuum liquid dryer uses a conveyor belt and its inner heating plate to quickly and efficiently dry malic acid slurry from a moisture content of 20% to 5%. However, malic acid material is already solid at a moisture content of 5%, and cannot be further dried without crushing and tumbling. Therefore, this invention feeds this 5% moisture content malic acid solid into a spiral dryer with a heating jacket for crushing and tumbling, and rapid heating and drying, thus solving the problems existing in the prior art. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the device structure of the present invention; In the diagram: 1-Raw material tank; 2-First screw pump; 3-Second screw pump; 4-First feed pipe; 5-Second feed pipe; 6-First cloth-feeding gun; 7-Second cloth-feeding gun; 8-Belt vacuum liquid dryer; 9-Heating plate; 10-Crawler belt; 11-Screw dryer; 12-Motor; 13-First stage discharge tank; 14-Intermediate pneumatic valve; 15-Second stage discharge tank; 16-Discharge pneumatic valve; 17-Hot water inlet; 18-Hot water outlet; 19-Steam inlet; 20-Drain valve; 21-Vacuum phase pipe; 22-Condenser; 23-Condensate pipe; 24-Condensate collection tank; 25-Tail gas pipe; 26-Vacuum unit; 27-Chilled water inlet; 28-Chilled water outlet; 29-Heating jacket. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings: After being metered by the first screw pump 2 and the second screw pump 3, the malic acid slurry in raw material tank 1 is fed into the belt vacuum liquid dryer 8 through the first feed pipe 4 and the second feed pipe 5, respectively. The slurry is then evenly distributed onto the conveyor belt 10 by the first distribution gun 6 and the second distribution gun 7. After heat exchange with the heating plate 9, the water content evaporates, decreasing from 20% to 5%, and the material changes from a liquid slurry to a blocky solid. It then falls into the spiral dryer 11 for further drying. In the spiral dryer 11, hot water enters through the hot water inlet 17 and exits through the hot water outlet 18. The moisture content of the material rapidly decreases after heat exchange with the hot water, and it finally enters the secondary discharge tank 15. When it is necessary to discharge the malic acid product from the secondary discharge tank 15, the intermediate pneumatic valve 14 is first closed, temporarily storing the malic acid product in the primary discharge tank 13. Then, the discharge pneumatic valve 16 is opened to discharge the dried malic acid product. After the product is discharged, close the discharge pneumatic valve 16, open the intermediate pneumatic valve, and continue to receive the product using the secondary discharge tank 15.

[0019] The motor 12 drives the spiral blades inside the spiral dryer 11 to rotate, thereby propelling and turning the material, which helps to enhance heat transfer and thus improve drying efficiency.

[0020] In the belt vacuum liquid dryer 8, the evaporated vapor phase enters the condenser 22 through the vapor phase pipe 21, and the condensed liquid enters the condensate collection tank 24 through the condensate pipe 23. The uncondensed tail gas is drawn into the vacuum unit 26 through the tail gas pipe 25 and then discharged. The chilled water in the condenser 22 enters through the chilled water inlet 27 and exits through the chilled water outlet 28.

[0021] The heat source in the belt vacuum liquid dryer 8 is provided through the steam inlet 19, and the condensate from the heat exchanged steam is discharged through the steam trap 20.

[0022] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A combined liquid and solid drying apparatus for malic acid, characterized in that: The system includes a belt vacuum liquid dryer and a spiral dryer. The belt vacuum liquid dryer has an inner cavity equipped with a heating plate on the inner side of the conveyor belt and a cloth-feeding gun for feeding the material onto the conveyor belt. The discharge port of the belt vacuum liquid dryer is connected to the inlet of the spiral dryer. The spiral dryer has a heating jacket on its casing. The inner cavity of the spiral dryer is equipped with a rotating shaft and spiral blades on the shaft. The rotating shaft is driven by a motor at one end of the spiral dryer. The discharge port of the spiral dryer is connected to a discharge tank. The discharge end of the raw material tank is connected to the cloth-feeding gun inside the belt vacuum liquid dryer through a screw pump and a feed pipe. The vapor phase pipe of the belt vacuum liquid dryer is connected to a condenser, and the condenser is then connected to a vacuum unit.

2. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The track consists of multiple tracks, and there are multiple heating plates on the inner side of the track. There are also multiple cloth-laying guns corresponding to each track. Each cloth-laying gun is supplied with raw materials by a screw pump. Thus, there are also multiple screw pumps, and all of the multiple screw pumps are supplied with raw materials from the same raw material tank.

3. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The discharge tank includes a primary discharge tank and a secondary discharge tank. The primary discharge tank is connected to the discharge port of the spiral dryer. The bottom outlet of the primary discharge tank is connected to the inlet of the secondary discharge tank through an intermediate pneumatic valve. The discharge end of the secondary discharge tank is connected to a discharge pneumatic valve.

4. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The condenser is filled with chilled water and has a chilled water inlet and a chilled water outlet. The condensate outlet pipe at the bottom of the condenser is connected to a condensate collection tank, and the exhaust gas pipe of the condenser is connected to a vacuum unit.

5. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The belt vacuum liquid dryer has a heat source inlet and a drain valve. The heat source inlet is connected to the inlet end of the heating plate, and the outlet end of the heating plate is connected to the drain valve.

6. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The heating jacket of the spiral dryer has a heat source inlet and a heat source outlet.

7. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The heat source is hot water, steam, or heat transfer oil.

8. The combined liquid drying and solid drying apparatus for malic acid according to claim 1, characterized in that: The pneumatic valve may be an electric valve.

9. A combined process for a liquid drying and solid drying apparatus for malic acid according to any one of claims 1-8, characterized in that... include: (1) The vacuum unit evacuates the belt vacuum liquid dryer through the exhaust gas pipe, condenser and vapor phase pipe; (2) The material from the raw material tank is fed into the cloth gun in the belt vacuum liquid dryer through the screw pump and the feed pipe; (3) The cloth gun evenly distributes the raw material onto the conveyor belt inside the belt vacuum liquid dryer, and the conveyor belt moves forward slowly; (4) The malic acid liquid raw material on the track is heated by the heating plate inside the track, the water or solvent is evaporated, and the raw material is dried. (5) When the raw material is dried to a certain moisture content on the belt of the belt vacuum liquid dryer, it enters the feed port of the screw dryer from the discharge port of the belt vacuum liquid dryer. The raw material is pushed forward by the spiral blades inside the screw dryer while being turned over. During the turning and moving forward process, the raw material is heated and further dried by the heating jacket on the casing of the screw dryer. (6) After the raw materials are dried into qualified products in the spiral dryer, they enter the primary discharge tank and the secondary feed tank from the spiral dryer outlet. (7) When it is necessary to discharge the product from the secondary discharge tank, first close the intermediate pneumatic valve, open the discharge pneumatic valve, and discharge the product from the secondary discharge tank. (8) Then close the discharge pneumatic valve and open the intermediate pneumatic valve so that the secondary discharge tank can continue to receive products.

10. The combined micro-drying and solid-state drying process for malic acid according to claim 9, characterized in that: In step (5), the raw material is dried on the conveyor belt to a certain moisture content of 5%; in step (6), the raw material is dried in the screw dryer to become a qualified product with a moisture content of <0.5%.

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