A sodium citrate evaporation crystallization system

Abstract

This invention discloses a sodium citrate evaporation and crystallization system. The outlet of the feed pump is connected to the tube-side inlet of the steam preheater via the cold side of the condensate preheater. The tube-side outlet of the steam preheater is connected to the primary circulation bypass port of the primary falling film evaporator. The bottom outlet of the primary falling film evaporator is connected to the primary circulation pipe via a falling film circulation pump, and also to the top inlet of the secondary forced evaporator via a primary transfer pump. The bottom outlet of the secondary forced evaporator is connected to the top inlet of the secondary forced evaporator, and also to the sodium citrate discharge pipe via a secondary discharge pump. The top exhaust ports of the primary evaporator separator and the secondary FC crystallizer are both connected to the inlet of the MVR compressor. The outlet of the MVR compressor is connected to the heat source inlet of the steam preheater, the primary falling film evaporator, and the secondary forced evaporator via a compressed steam pipe. This system has low energy consumption, reduces the residence time of the sodium citrate solution in the system, and increases the stability of material quality control.

Description

Technical Field

[0001] This utility model relates to an evaporation crystallization system, and more particularly to a sodium citrate evaporation crystallization system, belonging to the field of biochemical equipment technology. Background Technology

[0002] Sodium citrate is a white to colorless organic crystalline compound whose core characteristic is its excellent chelating / complexing ability. It is mainly used in four major fields: 1. Food and beverage: as a flavoring agent and stabilizer to improve product taste and texture; 2. Pharmaceuticals: used as an anticoagulant, expectorant, and diuretic, and in the preparation of injectable solutions; 3. Environmentally friendly detergents: replacing phosphorus-containing additives in the manufacture of non-toxic detergents; 4. Industrial technology: serving electroplating, brewing, and photographic chemicals through chelation.

[0003] Traditional sodium citrate production uses an intermittent concentration kettle process, which faces the following key bottlenecks: 1. The comprehensive energy consumption per ton of product reaches 0.35-0.4 tons of standard coal and 80-100 kWh of electricity, resulting in low overall production energy efficiency; 2. The sodium citrate product produced by the traditional process has a wide crystal particle size distribution and unstable quality control.

[0004] Chinese utility model patent CN218853510U discloses a continuous evaporation and crystallization device for sodium citrate, comprising a forced circulation evaporator, a mixing condenser, a vacuum pump, a gas-liquid separator, a circulating water pump, a cooling tower, a transfer vessel, and a crystal slurry pump. Pressure sensor interfaces and thickeners are installed at the upper and lower ends of the forced circulation evaporator, respectively. The thickener is connected to a vent valve. A circulation pipe and a heater are connected to the side wall of the forced circulation evaporator. The ends of the circulation pipe and the heater converge and are connected to the forced circulation pump. An electromagnetic flowmeter is connected to the feed inlet on the side wall of the circulation pipe, and the input end of the electromagnetic flowmeter is connected to a feed valve. This technical solution adopts a single-effect forced evaporation scheme, aiming to solve the problem of high overall energy consumption in traditional intermittent concentration kettle processes; however, the system still consumes a large amount of steam, resulting in high production costs, and the long residence time of materials in the system leads to unstable quality control. 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 sodium citrate evaporation crystallization system that can reduce production energy consumption, reduce the residence time of sodium citrate solution in the system, and increase the stability of material quality control.

[0008] To solve the above technical problems, this utility model provides a sodium citrate evaporation and crystallization system, comprising a feed pump whose inlet is connected to a sodium citrate feed pipe, an outlet of the feed pump connected to the cold-side inlet of a condensate preheater, a cold-side outlet of the condensate preheater connected to the tube-side inlet of a steam preheater, a tube-side outlet of the steam preheater connected to the top bypass port of the first-stage falling film evaporator, and a bottom outlet of the first-stage falling film evaporator connected to its top inlet via a falling film circulation pump and a first-stage circulation pipe. The bottom outlet of the first-stage falling film evaporator is also connected to the top inlet of a second-stage forced evaporator via a first-stage transfer pump, and the bottom outlet of the second-stage forced evaporator is connected to the circulating liquid inlet of a second-stage FC crystallizer via a second-stage forced circulation pump. The bottom outlet of the second-stage FC crystallizer is connected to the top inlet of the second-stage forced evaporator, and the bottom outlet of the second-stage forced evaporator is also connected to the sodium citrate discharge pipe via a second-stage discharge pump. A first-stage evaporation separator is connected to the bottom of the first-stage falling film evaporator, and the top exhaust ports of both the first-stage evaporation separator and the second-stage FC crystallizer are connected to the inlet of an MVR compressor. The compressor outlet is connected to the heat source inlet of the steam preheater, the first-stage falling film evaporator, and the second-stage forced evaporator via a compressed steam pipe.

[0009] As an improvement of this utility model, the shell-side exhaust ports of the first-stage falling film evaporator and the second-stage forced evaporator are connected to the hot-side inlet of the surface condenser through the non-condensable gas main pipe, and the cold side of the surface condenser is connected to the cooling water circulation pipe; the hot-side outlet of the surface condenser is connected to the middle inlet of the gas-liquid separator, and the top exhaust port of the gas-liquid separator is vented to the atmosphere through a vacuum pump.

[0010] As a further improvement of this utility model, the shell-side condensate drain of the steam preheater, the first-stage falling film evaporator, the second-stage forced evaporator, and the bottom outlet of the gas-liquid separator are respectively connected to the condensate tank. The outlet of the condensate tank is connected to the hot-side inlet of the condensate preheater through a condensate pump, and the hot-side outlet of the condensate preheater is connected to the condensate recovery pipe.

[0011] Compared with 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 falling film evaporators and forced evaporators. Compared with a single forced evaporation system, this improves the efficiency of the initial concentration process of sodium citrate, reduces production costs, and shortens the residence time of the material crystallization process in the system.

[0012] 2. The sodium citrate 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 the saturated steam generated by the system's evaporation, fully utilizing the heat from the evaporation to preheat the feed in two stages. In the preheating unit, the primary preheater uses a plate heat exchanger, which has high heat transfer efficiency and low heat loss, making full use of the residual heat from the condensate. The secondary preheating uses a shell-and-tube heat exchanger, utilizing the saturated steam generated by the material's evaporation to exchange heat with the material. This system significantly reduces the amount of live steam used during the material preheating process.

[0013] 3. The traditional intermittent concentration kettle process has been abandoned, replaced by an MVR falling film evaporator + forced evaporation process. A parallel steam operation mode is adopted, meaning the steam generated from the first-stage falling film evaporation and the second-stage forced evaporation enters the MVR compressor together. After heating, the steam serves as the heat source for the steam preheater, the first-stage falling film evaporator, and the second-stage forced evaporator, respectively. Firstly, in terms of evaporation energy efficiency, it saves 30-50% more energy than the traditional intermittent concentration kettle. Secondly, compared to the steam consumption per ton of water evaporated by a single forced evaporation system, the MVR system consumes very little steam except during startup and other special circumstances. This significantly reduces steam consumption and substantially lowers production and operating costs.

[0014] 4. The system employs an MVR falling film evaporation + forced evaporation crystallization process, using a series material handling configuration. After concentration by falling film evaporation, the material enters the forced evaporator via a primary transfer pump. Due to the risk of high-concentration sodium citrate agglomeration and pipe blockage, the concentration of the primary concentrate in this system is 50-54%. Compared to a single forced evaporation system, this significantly improves the system's evaporation efficiency, reduces the material's residence time in the forced evaporation system, and solves the problems of uneven product particle size distribution and severe crystal aggregation.

[0015] 5. Low-temperature evaporation avoids the negative effects of high temperatures on sodium citrate solution, such as the formation of fumaric acid impurities due to excessively high temperatures. Low-temperature evaporation controls the impurity formation rate to below 0.1%. Furthermore, low-temperature evaporation avoids lattice defects caused by high temperatures, improving product flowability and reducing agglomeration. By using a vacuum pump and MVR compressor in conjunction, maintaining negative pressure in the overall evaporation system, low-temperature evaporation is achieved, minimizing damage to the sodium citrate solution. Attached Figure Description

[0016] 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:

[0017] Figure 1 This is a flowchart of the sodium citrate evaporation and crystallization system of this utility model;

[0018] In the diagram: 1. Condensate preheater; 2. Steam preheater; 3. First-stage falling film evaporator; 4. First-stage evaporator separator; 5. Second-stage forced evaporator; 6. Second-stage FC crystallizer; 7. Liquid collection tank; 8. Surface condenser; 9. Condensate tank; 10. Gas-liquid separator;

[0019] P1. Feed pump; P2. Condensate pump; P3. Falling film circulation pump; P4. Primary transfer pump; P5. Secondary forced circulation pump; P6. Secondary discharge pump; P7. Accumulation pump; P8. Vacuum pump; H1. MVR compressor;

[0020] G1. Sodium citrate feed pipe; G2. Primary falling film steam outlet pipe; G3. Primary concentrate transfer pipe; G4. Secondary FC crystallization steam outlet pipe; G5. Compressed steam pipe; G6. Live steam pipe; G7. Condensate recovery pipe; G8. Cooling water circulation pipe; G9. Sodium citrate discharge pipe; G10. Non-condensable gas main pipe; ZT1. Mass flow meter. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] like Figure 1As shown, the sodium citrate evaporation and crystallization system of this invention includes a condensate preheater 1, a steam preheater 2, a primary falling film evaporator 3, a primary evaporator separator 4, a secondary forced evaporator 5, a secondary FC crystallizer 6, a liquid collection tank 7, a surface condenser 8, a condensate tank 9, an MVR compressor H1, and a vacuum pump P8. The outlet of the sodium citrate 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 cold-side inlet of the steam preheater 2, and the cold-side outlet of the steam preheater 2 is connected to the circulation pipe at the top inlet of the primary falling film evaporator 3. The lower sidewall of the primary falling film evaporator 3 is connected to the primary evaporator separator 4 via a connecting pipe, the bottom outlet of the primary falling film evaporator 3 is connected to the inlet of the falling film circulation pump P3, and the outlet of the falling film circulation pump P3 is connected to the top inlet of the primary falling film evaporator 3. The outlet at the bottom of the first-stage falling film evaporator 3 is also connected to the inlet of the first-stage transfer pump P4. The outlet of the first-stage transfer pump P4 is connected to the circulation pipe at the inlet of the second-stage forced evaporator 5 through the first-stage concentrate transfer pipe G3. The bottom of the second-stage material circulation pipe is connected to the circulation liquid inlet of the second-stage forced circulation pump P5 and the second-stage FC crystallizer 6. The bottom of the second-stage material circulation pipe is also connected to the inlet of the second-stage discharge pump P6. The outlet of the second-stage discharge pump P6 is connected to the sodium citrate discharge pipe G9 through the mass flow meter ZT1.

[0025] The top exhaust port of the first-stage evaporator separator 4 is connected to the first-stage falling film steam outlet pipe G2, and the top exhaust port of the second-stage FC crystallizer 6 is connected to the second-stage FC crystallizer steam outlet pipe G4. The outlets of the first-stage falling film steam outlet pipe G2 and the second-stage FC crystallizer steam outlet pipe G4 are connected to the inlet of the MVR compressor H1. The outlet of the MVR compressor H1 is connected to the heat source inlet of the steam preheater 2, the heat source inlet of the first-stage falling film evaporator 3, and the heat source inlet of the second-stage forced evaporator 5 through the compressed steam pipe G5.

[0026] The vacuum ports of the primary falling film evaporator 3 and the secondary forced evaporator 5 are connected to the non-condensable gas main pipe G10. The outlet of the non-condensable gas main pipe G10 is connected to the hot side inlet of the surface condenser 8, and the cold side of the surface condenser 8 is connected to the cooling water circulation pipe G8. The hot side outlet of the surface condenser 8 is connected to the middle inlet of the gas-liquid separator 10, and the top exhaust port of the gas-liquid separator 10 is connected to the suction port of the vacuum pump P8.

[0027] The inlet pipe of MVR compressor H1 and the condensate drain outlet of the casing of MVR compressor H1 are connected to condensate tank 7. The outlet of condensate tank 7 is connected to the inlet of condensate pump P7, and the outlet of condensate pump P7 is connected to condensate tank 9. The bottom drain outlets of the shell side of steam preheater 2, primary falling film evaporator 3, and secondary forced evaporator 5, as well as the bottom drain outlet of gas-liquid separator 10, are also connected to the inlet of condensate tank 9. The bottom drain outlet of condensate tank 9 is connected to the inlet of condensate pump P2. The outlet of condensate pump P2 is connected to the hot side inlet of condensate preheater 1, and the hot side outlet of condensate preheater 1 is connected to condensate recovery pipe G7.

[0028] The sodium citrate feed solution from feed pipe G1 has a temperature of approximately 50°C and a concentration of 30%-34%. It first enters the cold side of the condensate preheater 1 and is preheated to approximately 56°C. The hot side medium is the condensate pumped from condensate tank 9 by condensate pump P2. After primary preheating, the feed solution enters the cold side of the steam preheater 2 for secondary heating, raising the temperature to approximately 68°C. The hot side medium of the steam preheater 2 is the steam compressed by steam compressor H1. The condensate generated after heat exchange flows by gravity into condensate tank 9.

[0029] After two stages of preheating, the sodium citrate mixture at approximately 68°C enters the first-stage falling film evaporator 3 for evaporation. The heat source medium for the first-stage falling film evaporator 3 is the steam compressed by the steam compressor H1. The condensate generated after heat exchange flows by gravity into the condensate tank 9.

[0030] After primary evaporation, the concentration of the liquid reaches 50%-54%, and the outlet temperature of the primary falling film evaporator 3 is approximately 72°C. The liquid is pumped into the pipeline between the secondary forced evaporator 5 and the secondary FC crystallizer 6 via the primary transfer pump P4 and the primary concentrate transfer pipe G3 to participate in the secondary heating evaporation cycle. The heat source medium of the secondary forced evaporator 5 is the secondary steam compressed by the MVR compressor H1. The condensate generated after heat exchange flows into the condensate tank 9 by gravity. The material is finally pumped into the downstream section for further processing via the discharge pump P6 and the sodium citrate discharge pipe G9, with an outlet temperature of approximately 74°C.

[0031] The secondary steam generated after the sodium citrate solution is evaporated in the first-stage falling film evaporator 3 has a temperature of approximately 66°C. It undergoes vapor-liquid separation in the first-stage evaporator separator 4, and the separated liquid is discharged from the bottom of the first-stage evaporator separator 4. The steam after the first-stage evaporation and separation is discharged through the first-stage falling film steam outlet pipe G2 and enters the MVR compressor H1 for compression. The secondary steam generated after evaporation in the second-stage FC crystallizer 6 has a temperature of approximately 66°C. After evaporation, the secondary steam is discharged through the second-stage FC crystallizer steam outlet pipe G4 and enters the MVR compressor H1 for compression. The secondary steam from the first and second stages of evaporation is compressed by the MVR compressor H1 and then subjected to enthalpy and temperature increases to 82°C. The steam after enthalpy and temperature increases enters the steam preheater 2, the first-stage falling film evaporator 3, and the second-stage forced evaporator 5 as a heating source medium.

[0032] The non-condensable gas outlets of the first-stage falling film evaporator 3 and the second-stage forced evaporator 5 are connected to the non-condensable gas main pipe G10. The non-condensable gas main pipe G10 is connected to the hot side inlet of the surface cooler 8 to discharge non-condensable gases. The outlet of the surface cooler 8 is connected to the inlet of the vacuum pump P8. The vacuum pump P8 is used to extract non-condensable gas from the system to maintain the vacuum level of the system.

[0033] In this process, the feed sodium citrate solution concentration is 30%-34%, and the final output concentration is 66%. The use of a single-stage falling film evaporation concentrates the sodium citrate solution from 30%-34% to 50%-54%, significantly improving the system's evaporation efficiency and reducing the residence time of the material during evaporation and crystallization in the two-stage forced evaporation system. This solves the problems of uneven product particle size distribution and severe crystal aggregation. Through the MVR system, the steam consumption during production is only used to compensate for the heat lost by the system, significantly reducing production and operating costs. The material temperature in this process system is ≤75℃ to avoid the destructive effects of high temperatures on the sodium citrate solution.

[0034] 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 sodium citrate evaporation and crystallization system, comprising a feed pump (P1) whose inlet is connected to a sodium citrate stock feed pipe (G1), characterized in that: 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 tube side outlet of the steam preheater (2) is connected to the top bypass port of the first-stage circulating pipe 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) through the falling film circulating pump (P3) and the first-stage circulating pipe; the bottom outlet of the first-stage falling film evaporator (3) is also connected to the top inlet of the second-stage forced evaporator (5) through the first-stage transfer pump (P4), the bottom outlet of the second-stage forced evaporator (5) is connected to the circulating liquid inlet of the second-stage FC crystallizer (6) through the second-stage forced circulating pump (P5), the bottom outlet of the second-stage FC crystallizer (6) is connected to the top inlet of the second-stage forced evaporator (5), and the bottom outlet of the second-stage forced evaporator (5) is also connected to the sodium citrate discharge pipe (G9) through the second-stage discharge pump (P6); The bottom of the first-stage falling film evaporator (3) is connected to the first-stage evaporator separator (4). The top exhaust ports of the first-stage evaporator separator (4) and the second-stage FC crystallizer (6) are connected to the inlet of the MVR compressor (H1). The outlet of the MVR compressor (H1) is connected to the heat source inlet of the steam preheater (2), the first-stage falling film evaporator (3) and the second-stage forced evaporator (5) through the compressed steam pipe (G5).

2. The sodium citrate evaporation crystallization system according to claim 1, characterized in that: The shell-side exhaust ports of the first-stage falling film evaporator (3) and the second-stage forced evaporator (5) are connected to the hot-side inlet of the surface condenser (8) via the non-condensable gas main pipe (G10), and the cold side of the surface condenser (8) is connected to the cooling water circulation pipe (G8); the hot-side outlet of the surface condenser (8) is connected to the middle inlet of the gas-liquid separator (10), and the top exhaust port of the gas-liquid separator (10) is vented to the atmosphere via a vacuum pump (P8).

3. The sodium citrate evaporation crystallization system according to claim 2, characterized in that: The shell-side condensate drain of the steam preheater (2), the first-stage falling film evaporator (3), the second-stage forced evaporator (5), and the bottom outlet of the gas-liquid separator (10) 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) through the condensate pump (P2). The hot-side outlet of the condensate preheater (1) is connected to the condensate recovery pipe (G7).

Images