A citric acid evaporation concentration crystallization device and method

Abstract

The present application provides a citric acid evaporation concentration crystallization device and method, including a feed tank, a condensed water heat exchanger, a fresh steam heat exchanger, a first-effect evaporator, a first-effect separator, a second-effect evaporator, a second-effect separator, a third-effect evaporator, a third-effect separator, an intermediate storage tank, an FC crystallizer, a crystallization heat exchanger, a centrifuge and a mother liquid tank connected in sequence through pipelines, the feed port of the feed tank is connected to the workshop storage system; the steam outlet of the first-effect evaporator and the steam outlet of the first-effect separator are connected to the steam ejector; the FC crystallizer and the crystallization heat exchanger are connected through pipelines to form a circulating evaporation crystallization system. The system of the device operates in a negative pressure system, using steam ejection technology, multi-effect evaporation technology, and MVR evaporation technology, reducing the operating energy consumption to 22% of the original system, the system operates stably, has high thermal efficiency, and the crystal content of crystals below 200 mesh precipitated by the crystallization system is increased by more than 30%.

Description

Technical Field

[0001] The invention relates to the technical field of energy saving, and in particular to a citric acid evaporation, concentration and crystallization device and method. Background Art

[0002] Citric acid, also known as citric acid, has a wide range of uses. It is used in the food industry as an acidulant, antioxidant, and pH regulator, in the pharmaceutical industry as an anticoagulant and antacid, and in the chemical industry as a buffer, chelating agent, metal cleaning agent, mordant, gelling agent, toner, etc. The current industrial production method of citric acid includes: subjecting the citric acid fermentation broth to solid-liquid separation to obtain a citric acid clear solution, subjecting the citric acid clear solution to processes such as calcium salt method, acid hydrolysis method, and decolorization to obtain a citric acid purified solution, and after evaporation and concentration of the citric acid purified solution, it enters a crystallizer, continues to be concentrated to a crystal slurry, and enters a centrifuge for solid-liquid separation to obtain citric acid crystals and citric acid crystal mother liquor. Among them, the evaporation, concentration and crystallization process of citric acid purified liquid all adopts fresh steam heating, which accounts for a large proportion of energy consumption in the citric acid production process, which is not conducive to reducing the production cost of citric acid. In addition, fresh steam is used as the heat source of the crystallization system. After the citric acid slurry enters the centrifuge for solid-liquid separation, citric acid mother liquor and citric acid crystals are obtained, but the percentage of citric acid crystals with a particle size of less than 200 mesh in the total crystal amount is too low. Therefore, in order to reduce the energy consumption of evaporation and crystallization in the citric acid production process, reduce the production cost of citric acid, and increase the content of crystals below 200 mesh of citric acid crystals, it is of great significance to study the evaporation, concentration and crystallization process of citric acid.

[0003] The boiling point rise of citric acid solution is high, and the boiling point rises by about 13°C under saturated state. The high boiling point rise limits the number of effects of the evaporation crystallization system. Usually, the evaporation of the ion exchange liquid is 4 effects with TVR, and the evaporation of the mother liquor is 3 effects with TVR; currently, the evaporation concentration section and the anhydrous citric acid crystallization section in citric acid production are usually independent of each other, and both systems need to consume fresh steam and circulating cooling water, and the overall energy consumption of the system is high.

[0004] Therefore, it is necessary to provide an evaporation crystallization system that can reduce energy consumption and improve output and quality. Summary of the invention

[0005] The purpose of the present application is to provide a citric acid evaporation concentration crystallization device and method, in order to solve the problems of high energy consumption, low yield and poor product quality of the citric acid evaporation concentration system in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present application provides a citric acid evaporation, concentration and crystallization device, comprising a feed tank, a condensed water heat exchanger, a fresh steam heat exchanger, a first-effect evaporator, a first-effect separator, a second-effect evaporator, a second-effect separator, a triple-effect evaporator, a triple-effect separator, an intermediate storage tank, a crystallization heat exchanger, an FC crystallizer, a centrifuge and a mother liquid tank, wherein:

[0008] The condensate water heat exchanger comprises a first fluid pipeline and a first condensate water pipeline and a second condensate water pipeline. The first condensate water pipeline and the second condensate water pipeline respectively exchange heat with the fluid pipeline through the pipe wall, and the discharge port of the feed tank is connected to the first fluid pipeline; the water inlet of the first condensate water pipeline of the condensate water heat exchanger is connected to the condensate water outlet of the steam channel of the first-effect evaporator; the water inlet of the second condensate water pipeline of the condensate water heat exchanger is connected to the condensate water outlet of the second-effect evaporator and the third-effect evaporator;

[0009] The fresh steam heat exchanger comprises a steam pipeline and a second fluid pipeline, wherein the inlet of the second fluid pipeline is connected to the outlet of the first fluid pipeline; the steam inlet of the steam pipeline is connected to a steam regulating valve for controlling fresh steam to enter the fresh steam heat exchanger, and the steam outlet of the fresh steam heat exchanger is connected to a steam trap for controlling steam discharge;

[0010] The first-effect evaporator comprises a first fluid chamber and a steam channel for heating the first fluid chamber, the material inlet of the first fluid chamber is connected to the outlet of the second fluid pipeline, and the material outlet of the first fluid chamber is connected to the material inlet of the first-effect separator; the steam inlet of the steam channel is connected to the injection port of the steam ejector, the steam outlet of the first-effect separator is connected to the low-pressure steam interface of the steam ejector, and the high-pressure steam interface of the steam ejector is connected to the steam regulating valve for controlling fresh steam to enter the steam ejector;

[0011] The second-effect evaporator comprises a second fluid chamber and a steam channel for heating the second fluid chamber, the material inlet of the second fluid chamber is connected to the material outlet of the first-effect separator, and the material outlet of the second fluid chamber is connected to the material inlet of the second-effect separator; the steam inlet of the steam channel is connected to the low-pressure steam interface of the steam ejector;

[0012] The triple-effect evaporator comprises a third fluid chamber and a steam channel for heating the third fluid chamber, the material inlet of the third fluid chamber is connected to the material outlet of the second-effect separator, and the material outlet of the third fluid chamber is connected to the material inlet of the triple-effect separator; the steam inlet of the steam channel is connected to the steam outlet of the second-effect separator;

[0013] The material inlet of the intermediate storage tank is connected with the material outlet of the feed tank and the material outlet of the triple-effect separator;

[0014] The heat exchange crystallizer comprises a second fluid pipeline and a third condensed water channel for heat exchange with the second fluid pipeline, the material inlet of the second fluid pipeline is connected with the material outlet of the intermediate storage tank; the material outlet of the second fluid pipeline is connected with the material inlet of the FC crystallizer, the liquid outlet of the FC crystallizer is connected with the material inlet of the second fluid pipeline; the solid-liquid mixture outlet of the FC crystallizer;

[0015] The material inlet of the centrifuge is communicated with the solid-liquid mixture outlet of the FC crystallizer, and the liquid outlet of the centrifuge is communicated with the feed inlet of the mother liquid tank.

[0016] Preferably, the fluid pipeline is divided into an upstream part and a downstream part, the second condensed water pipeline is arranged in the upstream part and exchanges heat with the upstream part, and the first condensed water pipeline is arranged in the downstream part and exchanges heat with the downstream part.

[0017] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a vacuum system for providing a vacuum operating environment for the system, and the vacuum system is connected to the non-condensable gas pipeline of each effect evaporator.

[0018] Preferably, the citric acid evaporation, concentration and crystallization device also includes a steam compressor, which adopts a two-effect series form, that is, it includes a first steam compressor and a second steam compressor, the steam inlet of the first steam compressor is connected to the steam outlet of the three-effect separator, the steam outlet of the first steam compressor is connected to the steam inlet of the second steam compressor, the steam outlet of the second steam compressor is connected to the steam inlet of the crystallization heat exchanger, and the steam outlet of the crystallization heat exchanger is connected to the steam inlet of the second condenser.

[0019] Preferably, the citric acid evaporation, concentration and crystallization device also includes a first condenser and a second condenser, the steam outlets of the first-effect evaporator, the second-effect evaporator and the third-effect evaporator are interconnected and connected to the steam inlet of the first condenser; the steam outlet of the crystallization heat exchanger is connected to the steam inlet of the second condenser.

[0020] More preferably, a first vacuum condensing water pump and a first vacuum pump are sequentially provided at the rear end of the water outlet of the first condenser; and a second vacuum condensing water pump and a second vacuum pump are sequentially provided at the rear end of the water outlet of the second condenser.

[0021] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a feed pump for controlling the material to enter the condensate heat exchanger, and the feed pump is arranged on the pipeline between the first discharge port of the feed tank and the feed port of the condensate heat exchanger.

[0022] More preferably, the feed pump is a centrifugal feed pump, and the material in the feed tank is automatically pumped into the condensate heat exchanger by the centrifugal feed pump, and the flow rate of the centrifugal feed pump is controlled by a frequency converter.

[0023] Preferably, the citric acid evaporation, concentration and crystallization device also includes a first-effect condensation water pump for controlling condensation water to enter the condensation water heat exchanger, and the first-effect condensation water pump is arranged on the pipeline between the first water inlet of the condensation water heat exchanger and the condensation water outlet of the first-effect evaporator.

[0024] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a first-effect material pump for controlling the material to enter the second-effect evaporator, and the first-effect material pump is arranged on the pipeline between the discharge port of the first-effect separator and the feed port of the second-effect evaporator.

[0025] Preferably, the citric acid evaporation, concentration and crystallization device also includes a second-effect condensation water pump for controlling condensation water to enter the condensation water heat exchanger, and the second-effect condensation water pump is arranged on the pipeline between the second water inlet of the condensation water heat exchanger and the second-effect evaporator.

[0026] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a second-effect material pump for controlling the material to enter the second-effect evaporator, and the second-effect material pump is arranged on the pipeline between the discharge port of the second-effect separator and the feed port of the triple-effect evaporator.

[0027] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a three-effect material pump for controlling the reflux of materials to the three-effect evaporator, and the three-effect material pump is arranged on the pipeline between the discharge port and the feed port of the three-effect evaporator.

[0028] Preferably, the citric acid evaporation, concentration and crystallization device also includes a triple-effect condensation water pump for controlling the condensation water to enter the condensation water heat exchanger, and the second-effect condensation water pump is arranged on the pipeline between the second water inlet of the condensation water heat exchanger and the condensation water outlet of the triple-effect evaporator.

[0029] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a concentration discharge pump for controlling the material to enter the intermediate relay tank, and the concentration discharge pump is arranged on the pipeline between the discharge port of the triple-effect separator and the feed port of the intermediate relay tank.

[0030] Preferably, the citric acid evaporation, concentration and crystallization device also includes a crystallization feed pump for pumping the material in the intermediate storage tank into the circulating material pipeline of the FC crystallizer, and the crystallization feed pump is arranged on the pipeline between the discharge port of the intermediate storage tank and the circulating discharge port of the FC crystallizer.

[0031] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a circulation pump for pumping the material in the FC crystallizer into the crystallization heat exchanger for heating, and the circulation pump is arranged on the pipeline between the circulation outlet of the FC crystallizer and the material inlet of the crystallization heat exchanger.

[0032] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a crystallization condensed water pump for discharging condensed water in the crystallizer heat exchanger, and the crystallization condensed water pump is arranged at the condensed water outlet of the crystallizer heat exchanger.

[0033] Preferably, the citric acid evaporation, concentration and crystallization device further comprises a crystallization discharge pump for pumping the material in the FC crystallizer into the centrifuge, and the crystallization discharge pump is arranged on the pipeline between the discharge port of the FC crystallizer and the centrifuge.

[0034] Preferably, the citric acid evaporation, concentration and crystallization device also includes a cooling water pump for pumping softened water into the steam inlet of the steam compressor, and the cooling water pump is arranged on the pipeline between the workshop softened water tank and the steam inlet of the steam compressor.

[0035] The second aspect of the present application provides a citric acid evaporation concentration crystallization method, comprising:

[0036] ——Fresh steam process: start the machine, control the fresh steam to enter the fresh steam heat exchanger to preheat the material by automatically controlling the steam regulating valve, and preheat the material in the fresh steam heat exchanger to the evaporator temperature required by the process, and use the temperature of the material in the subsequent pipeline of the fresh steam heat exchanger as the signal to control the opening of the steam regulating valve in the automatic control mode, so as to control the temperature of the material entering the first-effect evaporator to the material bubble point temperature;

[0037] By automatically controlling the steam regulating valve, fresh steam is controlled to enter the steam ejector, and the secondary steam of the first-effect separator is ejected through the steam ejector. The fresh steam enters the first-effect evaporator to heat the material, and the temperature of the secondary steam after the vapor-liquid separation of the first-effect separator is used as a signal to control the opening of the steam regulating valve in the automatic control mode, so as to control the temperature of the secondary steam to the evaporation temperature required by the process;

[0038] - Secondary steam process: After the vapor-liquid separation in the first-effect separator, the secondary steam is partially ejected by the steam ejector and then enters the second-effect evaporator to heat the material in the second-effect evaporator;

[0039] The secondary steam generated after the vapor-liquid separation in the second-effect separator enters the third-effect evaporator to heat the material in the third-effect evaporator;

[0040] The secondary steam generated after the three-effect separator performs vapor-liquid separation is passed through the steam compressor to increase the temperature and pressure, and then enters the crystallization heat exchanger as a heat source to heat the material;

[0041] The secondary steam generated by the FC crystallizer enters the crystallization condenser and is condensed into condensed water after heat exchange with the circulating cooling water;

[0042] ——Condensate flow: the condensate generated by the first-effect evaporator is pumped into the condensate heat exchanger through the first-effect condensate pump;

[0043] The condensed water produced by the second-effect evaporator and the third-effect evaporator is collected by the second-effect condensed water pump and the third-effect condensed water pump and then pumped into the condensed water heat exchanger;

[0044] The crystallization heat exchanger exchanges heat with the secondary steam compressed by the steam compressor, and discharges the condensed water;

[0045] The crystallization condenser condenses the secondary steam generated by the FC crystallizer, and the condensed water is discharged;

[0046] ——Material flow: the material enters the condensate heat exchanger from the feed tank for first-effect and second-effect preheating, then enters the fresh steam heat exchanger for third-effect preheating, then enters the first-effect evaporator for heating, the material temperature entering the first-effect evaporator is controlled to be the material bubble point temperature, then enters the first-effect separator for vapor-liquid separation, after separation, the material enters the second-effect evaporator for heating, then enters the second-effect separator for vapor-liquid separation, after separation, the material enters the three-effect evaporator for heating, then enters the three-effect separator for vapor-liquid separation, after separation, the material enters the intermediate relay tank for temporary storage, and then enters the material circulation system composed of the crystallization heat exchanger and the FC crystallizer, the material is concentrated to crystallization in the circulating crystallization system and then enters the centrifuge, solid-liquid separation is carried out in the centrifuge, the liquid after separation is the mother liquor entering the mother liquor tank, and the solid is citric acid crystals.

[0047] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0048] (1) The present invention adopts the method of using the steam generated in the device to heat the device itself, thereby reducing the energy consumption of evaporation, concentration and crystallization of citric acid purification liquid in the traditional citric acid production process to 22% of the original system;

[0049] (2) The steam compressor of the present invention adopts a two-effect series connection form, realizing the open-loop utilization of the steam compressor in the citric acid industry;

[0050] (3) The present invention uses secondary steam instead of fresh steam as the heat source of the crystallization heat exchanger for heating, thereby increasing the content of crystals below 200 mesh in the crystallization system by more than 30%;

[0051] (4) The device of the present invention adopts a fully automatic intelligent control system, which can realize one-button intelligent start and stop, and can monitor the operating status of the equipment in the device through software, and obtain corresponding control feedback after analysis;

[0052] (5) The steam compressor in the device of the present invention adopts variable frequency control. In actual operation, the steam compressor can be automatically controlled by variable frequency according to different working conditions, so that the operating capacity can be between 60% and 100% of the design load. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 1 is a schematic diagram of the structure of the citric acid evaporation, concentration and crystallization device of Example 1;

[0054] Figure 2 This is a schematic diagram of the structure of the citric acid evaporation, concentration and crystallization device of Example 2;

[0055] Figure 3 This is a schematic diagram of the structure of the citric acid evaporation, concentration and crystallization device of Example 3;

[0056] Figure 4 It is a schematic diagram of the structure of the citric acid evaporation, concentration and crystallization device of Example 4.

[0057] Among them, 1-feed tank 1, 2-condensate heat exchanger, 3-fresh steam heat exchanger, 4-first effect evaporator, 5-first effect separator, 6-steam ejector, 7-second effect evaporator, 8-second effect separator, 9-third effect evaporator, 10-third effect separator, 11-intermediate storage tank, 12-crystallization heat exchanger, 13-FC crystallizer, 14-centrifuge, 15-mother liquor tank, 16-steam compressor, 17-feed pump, 18-first effect condensate pump , 19-first effect material pump, 20-second effect condensing water pump, 21-second effect material pump, 22-third effect material pump, 23-third effect condensing water pump, 24-concentration discharge pump, 25-first vacuum condensing water pump, 26-first vacuum pump, 27-crystallization condensing water pump, 28-circulation pump, 29-crystallization discharge pump, 30-second vacuum condensing water pump, 31-second vacuum pump, 32-first condenser, 33-second condenser, 34-crystallization feed pump. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0059] Example 1

[0060] like Figure 1 As shown, a citric acid evaporation concentration crystallization device comprises a feed tank 1, a condensed water heat exchanger 2, a fresh steam heat exchanger 3, a first-effect evaporator 4, a first-effect separator 5, a second-effect evaporator 7, a second-effect separator 8, a third-effect evaporator 9, a third-effect separator 10, an intermediate storage tank 11, an FC crystallizer 13, a crystallization heat exchanger 12, a centrifuge 14 and a mother liquid tank 15 which are sequentially connected by pipelines, wherein:

[0061] The feed port of the feed tank 1 is connected to the workshop storage system; the first water inlet of the condensate heat exchanger 2 is connected to the condensate outlet of the first-effect evaporator 4, and the second water inlet of the condensate heat exchanger 2 is connected to the condensate outlets of the second-effect evaporator 7 and the third-effect evaporator 9; the steam inlet of the fresh steam heat exchanger 3 is connected to the steam regulating valve for controlling the fresh steam to enter the fresh steam heat exchanger 3, and the steam outlet of the fresh steam heat exchanger 3 is connected to the steam trap for controlling the steam discharge; the steam outlet of the first-effect evaporator 4 is connected to the first steam interface of the steam ejector 6, the steam outlet of the first-effect separator 5 is connected to the second steam interface of the steam ejector 6, and the third steam interface of the steam ejector 6 is connected to the steam regulating valve for controlling the fresh steam to enter the steam ejector 6; the FC crystallizer 13 is connected to the crystallization heat exchanger 12 through a pipeline to form a circulating evaporation crystallization system.

[0062] The working principle of a citric acid evaporation, concentration and crystallization device provided in this embodiment is as follows:

[0063] The feed tank 1 is connected to the workshop storage system through a pipeline, and the feed tank 1 provides materials for the citric acid evaporation, concentration and crystallization process and device; the condensate heat exchanger 2 and the fresh steam heat exchanger 3, the condensate heat exchanger 2 and the feed tank 1 are connected through a pipeline, the condensate heat exchanger 2 is connected with a fresh steam condensate tank and a secondary steam condensate tank, the fresh steam condensate in the fresh steam condensate tank enters the condensate heat exchanger 2 to preheat the material in one effect, and the secondary steam condensate in the secondary steam condensate tank enters the condensate heat exchanger 2 to preheat the material in two effects, that is, the material in the feed tank 1 is preheated twice through the condensate heat exchanger 2, the fresh steam heat exchanger 3 is connected with a steam regulating valve and a steam trap, and the fresh steam is controlled by the steam regulating valve to enter the fresh steam heat exchanger 3 to preheat the material in three effects, that is, the material in the condensate heat exchanger 2 enters the fresh steam heat exchanger 3 for the third preheating.

[0064] The first-effect evaporator 4 is connected to the fresh steam heat exchanger 3 through a pipeline. The material enters the first-effect evaporator 4 for heating after passing through the fresh steam heat exchanger 3. The first-effect evaporator 4 is connected to the steam ejector 6 through a pipeline. The steam ejector 6 is connected to a steam regulating valve. The steam regulating valve controls the fresh steam to enter the steam ejector 6, and ejects the secondary steam separated by the first-effect separator 5 at a ratio of 1:1.

[0065] The first-effect separator 5 is connected to the first-effect evaporator 4 through a pipeline. After being heated by the first-effect evaporator 4, the material enters the first-effect separator 5 for vapor-liquid separation. A portion of the secondary steam from the vapor-liquid separation of the first-effect separator 5 is ejected by the steam ejector 6. The temperature of the material entering the first-effect separator 5 after passing through the fresh steam heat exchanger 3 and the first-effect evaporator 4 is the bubble point temperature of the material under the corresponding pressure.

[0066] The second-effect evaporator 7 is connected to the material outlet of the first-effect separator 5 through a pipeline, and the material enters the second-effect evaporator 7 from the material outlet of the first-effect separator 5 for heating. The second-effect evaporator 7 is connected to the secondary steam outlet of the first-effect separator 5 through a pipeline, and the secondary steam after vapor-liquid separation in the first-effect separator 5 enters the second-effect evaporator 7 to heat the material in the second-effect evaporator 7.

[0067] The second-effect separator 8 is connected to the second-effect evaporator 7 through a pipeline. The material is heated by the second-effect evaporator 7 and enters the second-effect separator 8 for vapor-liquid separation. The temperature of the material entering the second-effect separator 8 after passing through the second-effect evaporator 7 is the bubble point temperature of the material under the corresponding pressure of the material.

[0068] The triple-effect evaporator 9 is connected to the material outlet of the second-effect separator 8 through a pipeline, and the material enters the triple-effect evaporator 9 from the material outlet of the second-effect separator 8 to be heated. The triple-effect evaporator 9 is connected to the secondary steam outlet of the second-effect separator 8 through a pipeline, and the secondary steam after the vapor-liquid separation of the second-effect separator 8 enters the triple-effect evaporator 9 to heat the material in the triple-effect evaporator 9.

[0069] The three-effect separator 10 is connected to the three-effect evaporator 9 through a pipeline. The material is heated by the three-effect evaporator 9 and enters the three-effect separator 10 for vapor-liquid separation. The temperature of the material entering the three-effect separator 10 through the three-effect evaporator 9 is the bubble point temperature of the material under the corresponding pressure of the material.

[0070] The intermediate storage tank 11 is connected to the material outlet of the triple-effect separator 10 through a pipeline, and the intermediate storage tank 11 is used to store the concentrated material to provide material for the crystallization process.

[0071] The FC crystallizer 13 is connected to the crystallization heat exchanger 12 through a pipeline to form a circulating evaporation crystallization system. The secondary steam separated from the gas and liquid by the triple-effect separator 10 enters the steam inlet of the crystallization heat exchanger 12 to heat the material in the crystallization heat exchanger 12. The material passes through the crystallization heat exchanger 12 and the FC crystallizer 13 for evaporation and concentration, and then enters the centrifuge 14 for solid-liquid separation. The separated liquid is the mother liquor entering the mother liquor tank 15, and the solid is citric acid crystals.

[0072] Example 2

[0073] Based on Example 1, this example adds a vacuum system and a steam compressor, such as Figure 2 As shown, the vacuum system is used to provide a vacuum operating environment for the system, and the vacuum system is connected to the non-condensable gas pipeline of each effect evaporator; the steam compressor 16 adopts a two-effect series form, that is, it includes a first steam compressor 16 and a second steam compressor 16, the steam inlet of the first steam compressor 16 is connected to the steam outlet of the three-effect separator 10, the steam outlet of the first steam compressor 16 is connected to the steam inlet of the second steam compressor 16, and the steam outlet of the second steam compressor 16 is connected to the steam inlet of the crystallization heat exchanger 12.

[0074] Specifically, the steam inlet of the steam compressor 16 is connected to the secondary steam outlet of the triple-effect separator 10 through a pipeline, and the steam outlet of the steam compressor 16 is connected to the steam inlet of the crystallization heat exchanger 12 through a pipeline. The secondary steam generated by the vapor-liquid separation of the triple-effect separator 10 passes through the steam compressor 16, and its pressure and temperature are increased, and the secondary steam enters the crystallization heat exchanger 12 as a heat source.

[0075] Example 3

[0076] Based on Example 2, this embodiment further provides a first condenser 32 and a second condenser 33. Figure 3 As shown, the steam outlets of the first-effect evaporator 4 , the second-effect evaporator 7 , and the third-effect evaporator 9 are interconnected and connected to the steam inlet of the first condenser 32 ; the steam outlet of the crystallization heat exchanger 12 is connected to the steam inlet of the second condenser 33 .

[0077] More preferably, a first vacuum condensing water pump 25 and a first vacuum pump 26 are sequentially provided at the rear end of the water outlet of the first condenser 32; a second vacuum condensing water pump 30 and a second vacuum pump 31 are sequentially provided at the rear end of the water outlet of the second condenser 33.

[0078] Example 4

[0079] Based on Example 3, this embodiment adds a feed pump 17, a first-effect condensate pump 18, a first-effect material pump 19, a second-effect condensate pump 20, a second-effect material pump 21, a third-effect material pump 22, a third-effect condensate pump 23, a concentration discharge pump 24, a crystallization feed pump 34, a circulation pump 28, a crystallization condensate pump 27, a crystallization discharge pump 29, and a cooling water pump, such as Figure 4 shown.

[0080] The feed pump 17 is disposed on a pipeline between the first discharge port of the feed tank 1 and the feed port of the condensate heat exchanger 2 , and the feed pump 17 is used to control the material to enter the condensate heat exchanger 2 .

[0081] More preferably, the feed pump 17 is a centrifugal feed pump 17, and the material in the feed tank 1 is automatically pumped into the condensate heat exchanger 2 by the centrifugal feed pump 17, and the flow rate of the centrifugal feed pump 17 is controlled by a frequency converter.

[0082] The first-effect condensate pump 18 is disposed on a pipeline between the first water inlet of the condensate heat exchanger 2 and the condensate outlet of the first-effect evaporator 4 , and the first-effect condensate pump 18 is used to control the condensate to enter the condensate heat exchanger 2 .

[0083] The first-effect material pump 19 is arranged on the pipeline between the discharge port of the first-effect separator 5 and the feed port of the second-effect evaporator 7 , and the first-effect material pump 19 is used to control the material to enter the second-effect evaporator 7 .

[0084] The second-effect condensate pump 20 is disposed on a pipeline between the second water inlet of the condensate heat exchanger 2 and the second-effect evaporator 7 , and is used to control the condensate to enter the condensate heat exchanger 2 .

[0085] The second-effect material pump 21 is arranged on the pipeline between the discharge port of the second-effect separator 8 and the feed port of the third-effect evaporator 9 , and the second-effect material pump 21 is used to control the material to enter the second-effect evaporator 7 .

[0086] The three-effect material pump 22 is arranged on the pipeline between the discharge port and the feed port of the three-effect evaporator 9 , and the three-effect material pump 22 is used to control the material to flow back to the three-effect evaporator 9 .

[0087] The second-effect condensate pump 20 is arranged on the pipeline between the second water inlet of the condensate heat exchanger 2 and the condensate outlet of the third-effect evaporator 9 , and the third-effect condensate pump 23 is used to control the condensate to enter the condensate heat exchanger 2 .

[0088] The concentrate discharge pump 24 is disposed on a pipeline between the discharge port of the three-effect separator 10 and the feed port of the intermediate relay tank 11 , and the concentrate discharge pump 24 is used to control the material to enter the intermediate relay tank 11 .

[0089] The crystallization feed pump 34 is arranged on the pipeline between the discharge port of the intermediate storage tank 11 and the circulation discharge port of the FC crystallizer 13 , and the crystallization feed pump 34 is used to pump the material in the intermediate storage tank 11 into the circulation material pipeline of the FC crystallizer 13 .

[0090] The circulation pump 28 is disposed on a pipeline between the circulation outlet of the FC crystallizer 13 and the material inlet of the crystallization heat exchanger 12 . The circulation pump 28 is used to pump the material in the FC crystallizer 13 into the crystallization heat exchanger 12 for heating.

[0091] The crystallization condensation water pump 27 is arranged at the condensation water outlet of the crystallizer heat exchanger, and the crystallization condensation water pump 27 is used to discharge the condensation water in the crystallizer heat exchanger.

[0092] The crystallization discharge pump 29 is disposed on a pipeline between the discharge port of the FC crystallizer 13 and the centrifuge 14 , and the crystallization discharge pump 29 is used to pump the material in the FC crystallizer 13 into the centrifuge 14 .

[0093] The cooling water pump is arranged on the pipeline between the workshop softened water tank and the steam inlet of the steam compressor 16. The cooling water pump pumps softened water into the steam inlet of the steam compressor to ensure that the steam compressed by the steam compressor 16 is saturated steam to prevent the generation of overheated steam.

[0094] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A citric acid evaporation, concentration and crystallization device, characterized in that: It includes a feed tank, a condensate heat exchanger, a fresh steam heat exchanger, a first-effect evaporator, a first-effect separator, a second-effect evaporator, a second-effect separator, a third-effect evaporator, a third-effect separator, an intermediate storage tank, a crystallization heat exchanger, a FC crystallizer, a centrifuge and a mother liquid tank, among which, The condensate water heat exchanger comprises a first fluid pipeline and a first condensate water pipeline and a second condensate water pipeline. The first condensate water pipeline and the second condensate water pipeline respectively exchange heat with the fluid pipeline through the pipe wall, and the discharge port of the feed tank is connected to the first fluid pipeline; the water inlet of the first condensate water pipeline of the condensate water heat exchanger is connected to the condensate water outlet of the steam channel of the first-effect evaporator; the water inlet of the second condensate water pipeline of the condensate water heat exchanger is connected to the condensate water outlet of the second-effect evaporator and the third-effect evaporator; The fresh steam heat exchanger comprises a steam pipeline and a second fluid pipeline, wherein the inlet of the second fluid pipeline is connected to the outlet of the first fluid pipeline; the steam inlet of the steam pipeline is connected to a steam regulating valve for controlling fresh steam to enter the fresh steam heat exchanger, and the steam outlet of the fresh steam heat exchanger is connected to a steam trap for controlling steam discharge; The first-effect evaporator comprises a first fluid chamber and a steam channel for heating the first fluid chamber, the material inlet of the first fluid chamber is connected to the outlet of the second fluid pipeline, and the material outlet of the first fluid chamber is connected to the material inlet of the first-effect separator; the steam inlet of the steam channel is connected to the injection port of the steam ejector, the steam outlet of the first-effect separator is connected to the low-pressure steam interface of the steam ejector, and the high-pressure steam interface of the steam ejector is connected to the steam regulating valve for controlling fresh steam to enter the steam ejector; The second-effect evaporator comprises a second fluid chamber and a steam channel for heating the second fluid chamber, the material inlet of the second fluid chamber is connected to the material outlet of the first-effect separator, and the material outlet of the second fluid chamber is connected to the material inlet of the second-effect separator; the steam inlet of the steam channel is connected to the low-pressure steam interface of the steam ejector; The triple-effect evaporator comprises a third fluid chamber and a steam channel for heating the third fluid chamber, the material inlet of the third fluid chamber is connected to the material outlet of the second-effect separator, and the material outlet of the third fluid chamber is connected to the material inlet of the triple-effect separator; the steam inlet of the steam channel is connected to the steam outlet of the second-effect separator; The material inlet of the intermediate storage tank is connected with the material outlet of the feed tank and the material outlet of the triple-effect separator; The crystallization heat exchanger comprises a second fluid pipeline and a third condensed water channel for heat exchange with the second fluid pipeline, the material inlet of the second fluid pipeline is connected with the material outlet of the intermediate storage tank; the material outlet of the second fluid pipeline is connected with the material inlet of the FC crystallizer, the liquid outlet of the FC crystallizer is connected with the material inlet of the second fluid pipeline; the solid-liquid mixture outlet of the FC crystallizer; The material inlet of the centrifuge is connected to the solid-liquid mixture outlet of the FC crystallizer, and the liquid outlet of the centrifuge is connected to the feed inlet of the mother liquid tank; The citric acid evaporation, concentration and crystallization device also includes a first-effect condensation water pump for controlling condensation water to enter the condensation water heat exchanger, and the first-effect condensation water pump is arranged on a pipeline between the first water inlet of the condensation water heat exchanger and the condensation water outlet of the first-effect evaporator; The citric acid evaporation, concentration and crystallization device also includes a concentration discharge pump for controlling the material to enter the intermediate relay tank, and the concentration discharge pump is arranged on the pipeline between the discharge port of the three-effect separator and the feed port of the intermediate relay tank.

2. A citric acid evaporation, concentration and crystallization device according to claim 1, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a vacuum system for providing a vacuum operating environment for the system, and the vacuum system is connected to the non-condensable gas pipeline of each effect evaporator.

3. A citric acid evaporation, concentration and crystallization device according to claim 1, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a first condenser and a second condenser. The steam outlets of the first-effect evaporator, the second-effect evaporator and the third-effect evaporator are interconnected and connected to the steam inlet of the first condenser; the steam outlet of the crystallization heat exchanger is connected to the steam inlet of the second condenser.

4. A citric acid evaporation, concentration and crystallization device according to claim 3, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a steam compressor, which adopts a two-effect series form, that is, it includes a first steam compressor and a second steam compressor, the steam inlet of the first steam compressor is connected to the steam outlet of the three-effect separator, the steam outlet of the first steam compressor is connected to the steam inlet of the second steam compressor, the steam outlet of the second steam compressor is connected to the steam inlet of the crystallization heat exchanger, and the steam outlet of the crystallization heat exchanger is connected to the steam inlet of the second condenser.

5. A citric acid evaporation, concentration and crystallization device according to claim 4, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a cooling water pump for pumping softened water into the steam inlet of the steam compressor. The cooling water pump is arranged on the pipeline between the workshop softened water tank and the steam inlet of the steam compressor.

6. A citric acid evaporation, concentration and crystallization device according to claim 1, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a feed pump for controlling the material to enter the condensate heat exchanger, and the feed pump is arranged on the pipeline between the first discharge port of the feed tank and the feed port of the condensate heat exchanger.

7. A citric acid evaporation, concentration and crystallization device according to claim 1, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a crystallization feed pump for pumping the material in the intermediate storage tank into the circulating material pipeline of the FC crystallizer. The crystallization feed pump is arranged on the pipeline between the discharge port of the intermediate storage tank and the circulating discharge port of the FC crystallizer.

8. A citric acid evaporation, concentration and crystallization device according to claim 1, characterized in that: The citric acid evaporation, concentration and crystallization device also includes a circulation pump for pumping the material in the FC crystallizer into the crystallization heat exchanger for heating. The circulation pump is arranged on the pipeline between the circulation outlet of the FC crystallizer and the material inlet of the crystallization heat exchanger.

9. A citric acid evaporation concentration crystallization method, characterized in that: The citric acid evaporation, concentration and crystallization device according to claim 1 comprises: Fresh steam process: start the machine, control the fresh steam to enter the fresh steam heat exchanger to preheat the material by automatically controlling the steam regulating valve, and preheat the material in the fresh steam heat exchanger to the evaporator temperature required by the process, and use the temperature of the material in the subsequent pipeline of the fresh steam heat exchanger as the signal to control the opening of the steam regulating valve in the automatic control mode, so as to control the temperature of the material entering the first-effect evaporator to the material bubble point temperature; By automatically controlling the steam regulating valve, fresh steam is controlled to enter the steam ejector, and the secondary steam of the first-effect separator is ejected through the steam ejector. The fresh steam enters the first-effect evaporator to heat the material, and the temperature of the secondary steam after the vapor-liquid separation of the first-effect separator is used as a signal to control the opening of the steam regulating valve in the automatic control mode, so as to control the temperature of the secondary steam to the evaporation temperature required by the process; Secondary steam process: the secondary steam generated after the vapor-liquid separation in the first-effect separator is partially ejected by the steam ejector and then enters the second-effect evaporator to heat the material in the second-effect evaporator; The secondary steam generated after the vapor-liquid separation in the second-effect separator enters the third-effect evaporator to heat the material in the third-effect evaporator; The secondary steam generated after the three-effect separator performs vapor-liquid separation is passed through a steam compressor to increase the temperature and pressure, and then enters the crystallization heat exchanger as a heat source to heat the material; The secondary steam generated by the FC crystallizer enters the crystallization condenser and is condensed into condensed water after heat exchange with the circulating cooling water; Condensate flow: the condensate generated by the first-effect evaporator is pumped into the condensate heat exchanger through the first-effect condensate pump; The condensed water produced by the second-effect evaporator and the third-effect evaporator is collected by the second-effect condensed water pump and the third-effect condensed water pump and then pumped into the condensed water heat exchanger; The crystallization heat exchanger exchanges heat with the secondary steam compressed by the steam compressor, and discharges the condensed water; The crystallization condenser condenses the secondary steam generated by the FC crystallizer, and the condensed water is discharged; Material flow: the material enters the condensate heat exchanger from the feed tank for first-effect and second-effect preheating, then enters the fresh steam heat exchanger for third-effect preheating, then enters the first-effect evaporator for heating, the material temperature entering the first-effect evaporator is controlled to be the material bubble point temperature, then enters the first-effect separator for vapor-liquid separation, after separation, the material enters the second-effect evaporator for heating, then enters the second-effect separator for vapor-liquid separation, after separation, the material enters the three-effect evaporator for heating, then enters the three-effect separator for vapor-liquid separation, after separation, the material enters the intermediate relay tank for temporary storage, and then enters the material circulation system composed of the crystallization heat exchanger and the FC crystallizer, the material is concentrated to crystallization in the circulating crystallization system and then enters the centrifuge, solid-liquid separation is carried out in the centrifuge, the liquid after separation is the mother liquor entering the mother liquor tank, and the solid is citric acid crystals.

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