Low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate

Abstract

This utility model discloses a low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate. The malic acid stock solution is fed sequentially into the cold side of a condensate preheater and a steam preheater via a feed pump, and then connected to the inlet of a first-stage falling film evaporator. The first-stage falling film evaporator outlet is connected to the inlet of a second-stage falling film evaporator via a transfer pump, and the second-stage falling film evaporator outlet is connected to the malic acid concentrate outlet pipe. The top exhaust port of the first-stage evaporator is connected to an MVR compressor, and the MVR compressor outlet is connected to the shell-side inlet of the first-stage falling film evaporator via a compressed steam pipe as a heat source. The top exhaust port of the second-stage evaporator is connected to a TVR steam jet pump, which injects live steam and connects it to the shell-side inlet of the second-stage falling film evaporator as a heat source. This system employs a low-temperature evaporation process to concentrate malic acid to over 80%, allowing it to cool and crystallize at room temperature, significantly reducing energy consumption and improving product quality and process stability.

Description

Technical Field

[0001] This utility model relates to an evaporation and concentration system, and more particularly to a low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate, belonging to the field of high-efficiency and energy-saving industrial technology. Background Technology

[0002] Sourness is an indispensable flavor in modern food industry. Whether in beverages or candies, it brings a refreshing sour taste experience to people's tongues and taste buds, a taste that is always unforgettable. The source of this sourness is acidulants frequently used in the food industry. Compared to citric acid, a common food acidulant, L-malic acid, found in fruits and vegetables such as apples, hawthorns, and grapes, has significant advantages. L-malic acid has a natural fruity aroma, a smooth and rounded taste, and a better balance of sourness than synthetic acids, more closely resembling the true taste of fruit juice. Furthermore, L-malic acid is low in calories and does not damage tooth enamel, thus not harming oral health. Combining deliciousness and health benefits, it is now widely used in the food industry.

[0003] Currently, the main production processes for L-malic acid include microbial fermentation, enzymatic conversion, and chemical synthesis, with the first two being the mainstream industrial production routes. Chemical synthesis suffers from low optical purity and heavy metal residues, making it difficult to meet food / pharmaceutical standards. Enzymatic conversion is suitable for high-end pharmaceutical / cosmetic products, but its production scale is smaller compared to bio-fermentation. Bio-fermentation is the mainstream method for the industrialization of L-malic acid. The bio-fermentation method for producing malic acid involves processes such as microbial fermentation, fermentation broth separation, evaporation and concentration, and cooling crystallization to obtain L-malic acid products. Malic acid products obtained through this production route meet food-grade standards.

[0004] Traditional malic acid evaporation and concentration processes employ multi-effect falling film evaporation, resulting in high energy consumption during the evaporation and concentration process. Furthermore, due to the high viscosity and high boiling point of high-concentration malic acid, the concentration of malic acid solutions produced by traditional evaporation and concentration processes is only around 50%. Moreover, the low concentration of malic acid solutions requires low heat exchange temperatures in the subsequent cooling and crystallization process, which greatly increases the energy consumption and quality control instability of the cooling and crystallization process. Utility Model Content

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0006] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate. The system uses low-temperature evaporation to concentrate malic acid to a high concentration, which allows it to be cooled and crystallized at room temperature, greatly reducing production energy consumption and improving the product quality and quality controllability of malic acid.

[0008] To solve the above technical problems, this utility model provides a low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate, including a malic acid raw material feed pipe G1. The malic acid raw material feed pipe G1 is connected to the cold side inlet of a condensate preheater 1 via a feed pump P1. The cold side outlet of the condensate preheater 1 is connected to the tube side inlet of a steam preheater 2. The tube side outlet of the steam preheater 2 is connected to the top inlet of a first-stage falling film evaporator 3. The bottom outlet of the first-stage falling film evaporator 3 is connected to the top inlet of the first-stage falling film evaporator 3 via a first-stage falling film circulation pump P3 and a first-stage circulation pipe. The bottom outlet of the first-stage falling film evaporator 3 is also connected to the top inlet of the second-stage falling film evaporator 5 via the first-stage transfer pump P4. The bottom outlet of the second-stage falling film evaporator 5 is connected to the top inlet of the second-stage falling film evaporator 5 via the second-stage falling film circulation pump P5 and the second-stage circulation pipe. The bottom outlet of the second-stage falling film evaporator 5 is also connected to the malic acid concentrate discharge pipe G5 via the second-stage discharge pump P6. The lower part of the first-stage falling film evaporator 3 is connected to the first-stage evaporator separator 4. The top exhaust port of the first-stage evaporator separator 4 is connected to the inlet of the MVR compressor H1. The outlet of the MVR compressor H1 is connected to the shell-side steam inlet of the first-stage falling film evaporator 3 through the compressed steam pipe G6. The lower part of the secondary falling film evaporator 5 is connected to the secondary evaporator separator 6. The top exhaust port of the secondary evaporator separator 6 is connected to the working steam inlet of the TVR steam jet pump H2. The power steam inlet of the TVR steam jet pump H2 is connected to the live steam pipe G7. The outlet of the TVR steam jet pump H2 is connected to the shell-side steam inlet of the falling film evaporator 5.

[0009] Furthermore, the shell-side exhaust port of the first-stage falling film evaporator 3 is connected to the hot-side inlet of the first-stage surface condenser 8 through a non-condensable gas main pipe, the hot-side outlet of the first-stage surface condenser 8 is connected to the middle inlet of the gas-liquid separator, the top exhaust port of the gas-liquid separator is connected to the hot-side inlet of the second-stage surface condenser 7, and the hot-side outlet of the second-stage surface condenser 7 is vented to the atmosphere through a vacuum pump P7.

[0010] Furthermore, the top exhaust port of the secondary evaporator 6 is also connected to the hot side inlet of the secondary surface condenser 7.

[0011] Furthermore, the shell-side inlet of the steam preheater 2 is connected to the live steam pipe G7. The shell-side condensate drains of the steam preheater 2, the first-stage falling film evaporator 3, the second-stage falling film evaporator 5, the first-stage surface condenser 8, and the second-stage surface condenser 7, as well as the bottom outlet of the gas-liquid separator, are respectively connected to the condensate tank 9. The outlet of the condensate tank 9 is connected to the hot-side inlet of the condensate preheater 1 via the condensate pump P2. The hot-side outlet of the condensate preheater 1 is connected to the condensate recovery pipe G9.

[0012] Compared to the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following: 1. The system adopts an evaporation and concentration process that combines MVR falling film evaporation and TVR falling film evaporation. With a multi-efficiency evaporation system, this system can produce a high concentration of malic acid solution of 80%-85%, and the concentrate can be cooled and crystallized at room temperature, which greatly reduces the energy consumption of malic acid production and significantly reduces production and operating costs.

[0013] 2. The malic acid solution undergoes two-stage preheating to raise the feed temperature, making it approximately equal to the system's evaporation temperature. This reduces the heat load required for the material to enter the system for evaporation and concentration. The primary preheating heat source is the condensate generated by the system, which simultaneously heats the material and recovers heat from the condensate. The secondary preheating heat source is fresh saturated steam, and the condensate generated from this steam enters a condensate tank. In the preheating unit, the primary preheater uses a plate heat exchanger, which boasts high heat transfer efficiency and minimal heat loss, maximizing the utilization of residual heat from the condensate. The secondary preheating uses a shell-and-tube heat exchanger, employing a small amount of fresh saturated steam to exchange heat with the material, significantly reducing the amount of live steam used during the material preheating process.

[0014] 3. The traditional multi-effect falling film evaporation and concentration process has been abandoned, replaced by an MVR falling film + TVR falling film evaporation process. The steam generated by the first-stage and second-stage falling film evaporation processes enters the MVR compressor and TVR steam jet pump, respectively. After being heated, the steam serves as the heat source for the first-stage and second-stage falling film evaporators, respectively. Firstly, in terms of evaporation energy efficiency, it saves approximately 40% more energy than the traditional multi-effect evaporation process. Secondly, compared to the single MVR falling film evaporation process, the MVR falling film + TVR falling film evaporation process can produce malic acid solutions with a high boiling point temperature rise, i.e., produce high-concentration malic acid solutions.

[0015] 4. The system employs a series material handling method. After primary falling film evaporation and concentration, the material is pumped into the secondary falling film evaporator via a primary transfer pump. Due to the high boiling point of high-concentration malic acid, a high-power MVR compressor is required. The primary concentrate concentration is approximately 60%, at which point the boiling point rise is relatively low. This significantly reduces MVR compressor power and energy consumption while ensuring low steam consumption for TVR evaporation and concentration. The secondary concentrate concentration is 80%-85%, at which point the compressor boiling point rise can reach approximately 20°C. The TVR falling film evaporation process concentrates the 60% primary concentrate to 80%-85%, at which point the alanine crystallization temperature is ≥30°C. This ensures reliable system operation while significantly reducing production energy consumption and increasing product quality controllability.

[0016] 5. Employing low-temperature MVR falling film evaporation combined with TVR falling film evaporation avoids the negative impacts of high temperatures on malic acid, such as the formation of fumaric acid impurities due to excessively high temperatures; it reduces the fumaric acid formation rate by 80% compared to traditional triple-effect evaporation processes. Through the coordinated operation of a primary surface condenser, a secondary surface condenser, a vacuum pump, an MVR compressor, and a TVR steam jet pump, the overall evaporation system maintains negative pressure for low-temperature evaporation, ensuring that the maximum temperature of the material is below 60℃, significantly reducing the destructive impact on the malic acid solution. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein: Figure 1 A flowchart of the low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate according to this utility model; In the diagram: 1. Condensate preheater; 2. Steam preheater; 3. First-stage falling film evaporator; 4. First-stage evaporator separator; 5. Second-stage falling film evaporator; 6. Second-stage evaporator separator; 7. Second-stage surface condenser; 8. First-stage surface condenser; 9. Condensate tank; P1. Feed pump; P2. Condensate pump; P3. First-stage falling film circulation pump; P4. First-stage transfer pump; P5. Second-stage falling film circulation pump; P6. Second-stage discharge pump; P7. Vacuum pump; H1. MVR compressor; H2. TVR steam jet pump.

[0018] G1. Malic acid feed pipe; G2. Steam outlet pipe of primary evaporator; G3. Transfer pipe of primary concentrate; G4. Steam outlet pipe of secondary evaporator; G5. Malic acid concentrate outlet pipe; G6. Compressed steam pipe; G7. Live steam pipe; G8. Circulating cooling water pipe; G9. Condensate recovery pipe; G10. Steam outlet pipe of primary surface cooler. Detailed Implementation

[0019] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0020] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0022] like Figure 1 As shown, the low-temperature evaporation and concentration system for producing high-concentration malic acid concentrate of this utility model includes a condensate preheater 1, a steam preheater 2, a primary falling film evaporator 3, a primary evaporator separator 4, a secondary falling film evaporator 5, a secondary evaporator separator 6, a secondary surface condenser 7, a primary surface condenser 8, and a condensate tank 9. The outlet of the malic acid feed pipe G1 is connected to the inlet of the feed pump P1. The outlet of the feed pump P1 is connected to the cold side inlet of the condensate preheater 1. The cold side outlet of the condensate preheater 1 is connected to the tube-side inlet of the steam preheater 2. The shell-side inlet of the steam preheater 2 is connected to the live steam pipe G7. The tube-side outlet of the steam preheater 2 is connected to the top feed port of the first-stage falling film evaporator 3. The lower part of the first-stage falling film evaporator 3 is connected to the first-stage evaporator separator 4. The bottom outlets of the first-stage falling film evaporator 3 and the first-stage evaporator separator 4 are connected to the inlet of the first-stage falling film circulation pump P3. The outlet of the first-stage falling film circulation pump P3 is connected to the top feed port of the first-stage falling film evaporator 3 through the first-stage circulation pipe, forming a circulation.

[0023] The bottom outlets of the primary falling film evaporator 3 and the primary evaporator separator 4 are also connected to the inlet of the primary transfer pump P4. The outlet of the primary transfer pump P4 is connected to the primary concentrate transfer pipe G3. The outlet of the primary concentrate transfer pipe G3 is connected to the top bypass port of the secondary circulation pipe of the secondary falling film evaporator 5. The bottom outlet of the secondary falling film evaporator 5 is connected to the inlet of the secondary falling film circulation pump P5. The outlet of the secondary falling film circulation pump P5 is connected to the top inlet of the secondary falling film evaporator 5 through the secondary circulation pipe. The lower part of the secondary falling film evaporator 5 is connected to the secondary evaporator separator 6. The bottom outlets of the secondary falling film evaporator 5 and the secondary evaporator separator 6 are also connected to the inlet of the secondary discharge pump P6. The outlet of the secondary discharge pump P6 is connected to the malic acid concentrate discharge pipe G5.

[0024] The top exhaust port of the first-stage evaporator separator 4 is connected to the inlet of the MVR compressor H1 through the steam outlet pipe G2 of the first-stage evaporator separator, and the outlet of the MVR compressor H1 is connected to the shell-side steam inlet of the first-stage falling film evaporator 3 through the compressed steam pipe G6.

[0025] The top exhaust port of the secondary evaporator 6 is connected to the working steam inlet of the TVR steam jet pump H2 through the secondary evaporator steam outlet pipe G4. The power steam inlet of the TVR steam jet pump H2 is connected to the live steam pipe G7. The outlet of the TVR steam jet pump H2 is connected to the shell-side steam inlet of the secondary falling film evaporator 5 through the mixing steam pipe.

[0026] The shell-side exhaust port of the first-stage falling film evaporator 3 is connected to the hot-side inlet of the first-stage surface condenser 8 through the non-condensable gas main pipe. The cold side of the first-stage surface condenser 8 is connected to the circulating cooling water pipe G8. The hot-side outlet of the first-stage surface condenser 8 is connected to the middle inlet of the gas-liquid separator. The top exhaust port of the gas-liquid separator is connected to the hot-side inlet of the second-stage surface condenser 7 through the steam outlet pipe G10 of the first-stage surface condenser. The cold side of the second-stage surface condenser 7 is also connected to the circulating cooling water pipe G8. The hot-side outlet of the second-stage surface condenser 7 is vented to the atmosphere through the vacuum pump P7.

[0027] The shell-side condensate drains of the steam preheater 2, the first-stage falling film evaporator 3, the second-stage falling film evaporator 5, the first-stage surface condenser 8, and the second-stage surface condenser 7, as well as the bottom outlet of the gas-liquid separator, are connected to the condensate tank 9. The outlet of the condensate tank 9 is connected to the hot-side inlet of the condensate preheater 1 via the condensate pump P2. The hot-side outlet of the condensate preheater 1 is connected to the condensate recovery pipe G9.

[0028] The malic acid feed liquid from the feed pipe G1 has a temperature of about 30°C and a concentration of about 20%. It first enters the cold side of the condensate preheater 1 and is preheated to about 51°C. The hot side medium is the condensate pumped out by the condensate pump P2 from the condensate tank 9. After the first stage of preheating, the feed liquid enters the cold side of the steam preheater 2 for a second stage of heating, and the temperature rises to about 57°C. The hot side medium of the steam preheater 2 is fresh steam. The condensate generated after heat exchange flows into the condensate tank 9 by gravity.

[0029] After two stages of preheating, the malic acid mixture at approximately 57°C enters the first-stage falling film evaporator 3 for evaporation and concentration. The heat source medium for the first-stage falling film evaporator 3 is the steam compressed by the MVR compressor H1, and the condensate generated after heat exchange flows by gravity into the condensate tank 9.

[0030] After primary evaporation, the feed concentration rises to approximately 60%, and the outlet temperature of the primary falling film evaporator 3 is approximately 57°C. The feed is then pumped into the secondary falling film evaporator 5 via primary transfer pump P4 and primary concentrate transfer pipe G3 for secondary evaporation and concentration. The heat source medium for the secondary falling film evaporator 5 is saturated steam mixed by TVR steam jet pump H2. The condensate generated after heat exchange flows by gravity into the condensate tank 9. The material after secondary concentration is finally pumped into the downstream processing section via secondary discharge pump P6 and malic acid concentrate discharge pipe G5 for further processing. The outlet temperature is approximately 57°C, and the feed concentration is 80%-85%.

[0031] The secondary steam generated after the malic acid solution is evaporated by the first-stage falling film evaporator 3 has a temperature of about 50°C. It is then separated into vapor and liquid by the first-stage evaporator separator 4. The separated liquid is discharged from the bottom of the first-stage evaporator separator 4. The steam after the first-stage evaporator separation is discharged through the steam outlet pipe G2 of the first-stage evaporator separator and enters the MVR compressor H1 for compression.

[0032] The secondary steam generated by the secondary falling film evaporator 5 has a temperature of about 37°C. After evaporation, the secondary steam undergoes vapor-liquid separation through the secondary evaporator separator 6. The separated liquid is discharged from the bottom of the secondary evaporator separator 6. The steam after the secondary evaporation separation is discharged through the steam outlet pipe G4 of the secondary evaporator separator and partially enters the TVR steam jet pump H2 to mix with the injected fresh steam for heating. The secondary steam from the primary and secondary evaporations is heated by the MVR compressor H1 and the TVR steam jet pump. After the enthalpy and temperature are increased, the steam enters the primary falling film evaporator 3 and the secondary falling film evaporator 5 as heating heat source media, respectively.

[0033] The non-condensable gas outlet of the first-stage falling film evaporator 3 is connected to the hot-side inlet of the first-stage surface condenser 8. After gas-water separation, the hot-side outlet of the surface condenser 8 enters the second-stage surface condenser 7 through the steam outlet pipe G10 of the first-stage surface condenser.

[0034] The steam discharged from the secondary evaporator 6 enters the hot side inlet of the surface condenser 7. The condensate generated after heat exchange flows into the condensate tank 9 by gravity. The other path enters the working steam inlet of the TVR steam jet pump H2. The shell-side outlet of the surface condenser 7 is connected to the inlet of the vacuum pump P7. The vacuum pump P7 is used to extract non-condensable vapors from the system to maintain the vacuum level of the system.

[0035] The feed malic acid concentration in this system is approximately 20%, and the final output concentration is 80%-85%. A single-stage MVR falling film evaporation system concentrates the malic acid solution from approximately 20% to approximately 60%. Using an MVR falling film evaporation system, aside from some steam preheating, there are no other energy consumptions during system operation. The low boiling point temperature rise of the feed liquid in the single-stage MVR evaporation system avoids the need for a high-temperature MVR compressor, further reducing system energy consumption. Furthermore, this system employs a two-stage TVR falling film evaporation system, suitable for malic acid solutions with high boiling point temperature rises, further increasing the concentration of the single-stage malic acid concentrate to 80%-85%. This concentrate can be cooled and crystallized at room temperature, reducing construction costs and energy consumption in the cooling and crystallization process while increasing the controllability of product quality.

[0036] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A low temperature evaporation concentration system for producing a high concentration malic acid concentrate comprising a malic acid feedstock feed pipe (Gl) characterized by: The malic acid feed pipe (G1) is connected to the cold side inlet of the condensate preheater (1) via the feed pump (P1). The cold side outlet of the condensate preheater (1) is connected to the tube side inlet of the steam preheater (2). The tube side outlet of the steam preheater (2) is connected to the top inlet of the first-stage falling film evaporator (3). The bottom outlet of the first-stage falling film evaporator (3) is connected to the top inlet of the first-stage falling film evaporator (3) via the first-stage falling film circulation pump (P3) and the first-stage circulation pipe. The bottom outlet of the first-stage falling film evaporator (3) is also connected to the top inlet of the second-stage falling film evaporator (5) via the first-stage transfer pump (P4). The bottom outlet of the second-stage falling film evaporator (5) is connected to the top inlet of the second-stage falling film evaporator (5) via the second-stage falling film circulation pump (P5) and the second-stage circulation pipe. The bottom outlet of the second-stage falling film evaporator (5) is also connected to the malic acid concentrate discharge pipe (G5) via the second-stage discharge pump (P6). The lower part of the first-stage falling film evaporator (3) is connected to the first-stage evaporator separator (4). The top exhaust port of the first-stage evaporator separator (4) is connected to the inlet of the MVR compressor (H1). The outlet of the MVR compressor (H1) is connected to the shell-side steam inlet of the first-stage falling film evaporator (3) through the compressed steam pipe (G6). The lower part of the secondary falling film evaporator (5) is connected to the secondary evaporator separator (6). The top exhaust port of the secondary evaporator separator (6) is connected to the working steam inlet of the TVR steam jet pump (H2). The power steam inlet of the TVR steam jet pump (H2) is connected to the live steam pipe (G7). The outlet of the TVR steam jet pump (H2) is connected to the shell-side steam inlet of the secondary falling film evaporator (5).

2. The low temperature evaporation concentration system for producing high concentration malic acid concentrate of claim 1, wherein: The shell-side exhaust port of the first-stage falling film evaporator (3) is connected to the hot-side inlet of the first-stage surface condenser (8) through the non-condensable gas main pipe. The hot-side outlet of the first-stage surface condenser (8) is connected to the middle inlet of the gas-liquid separator. The top exhaust port of the gas-liquid separator is connected to the hot-side inlet of the second-stage surface condenser (7). The hot-side outlet of the second-stage surface condenser (7) is vented to the atmosphere through the vacuum pump (P7).

3. The low temperature evaporation concentration system for producing high concentration malic acid concentrate of claim 2, wherein: The top exhaust port of the secondary evaporator (6) is also connected to the hot side inlet of the secondary surface condenser (7).

4. The low temperature evaporation concentration system for producing high concentration malic acid concentrate of claim 2, wherein: The shell-side inlet of the steam preheater (2) is connected to the live steam pipe (G7). The shell-side condensate drains of the steam preheater (2), the first-stage falling film evaporator (3), the second-stage falling film evaporator (5), the first-stage surface condenser (8), and the second-stage surface condenser (7), as well as the bottom outlet of the gas-liquid separator, are connected to the condensate tank (9). The outlet of the condensate tank (9) is connected to the hot-side inlet of the condensate preheater (1) via the condensate pump (P2). The hot-side outlet of the condensate preheater (1) is connected to the condensate recovery pipe (G9).

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