Citric acid secondary neutralization and vacuum filtration washing device

Abstract

This invention discloses a citric acid secondary neutralization and vacuum filtration washing device. The inlet of the dilute citric acid buffer tank is connected to the discharge pipe of miscellaneous sugars and dilute citric acid from the citric acid chromatography separation unit, and the outlet is connected to the cold side of a plate heat exchanger via a dilute citric acid transfer pump. A steam pipe is connected to the hot side of the heat exchanger, and condensate is returned to the condensate tank. The cold side outlet of the heat exchanger is connected to the dilute acid inlet of the first-stage secondary neutralization pot, and multiple secondary neutralization pots are connected in series. The filter cake from the tricalcium vacuum belt filter is discharged to the tricalcium slurry preparation tank, and the slurry preparation water is supplied by the condensate. The slurry preparation liquid enters the second secondary neutralization pot via the tricalcium slurry preparation pump. The outlet of the final-stage secondary neutralization pot is connected to a secondary neutralization variable frequency circulation pump and a secondary neutralization discharge pump, respectively. The outlet of the circulation pump returns to the first-stage secondary neutralization pot, and the outlet of the discharge pump is connected to the slurry distributor of the calcium hydrogen vacuum belt filter. This device can reduce the water and acid consumption of the chromatography separation system and improve the citric acid yield.

Description

Technical Field

[0001] This utility model relates to a citric acid production apparatus, and more particularly to a citric acid secondary neutralization and vacuum filtration washing apparatus, belonging to the technical field of citric acid production equipment. Background Technology

[0002] The industrial production of citric acid mainly relies on microbial fermentation. However, the fermentation broth contains a large number of impurities in addition to citric acid. To obtain industrial-grade or food-grade citric acid that meets national standards, impurities must be removed through extraction and purification processes. The neutralization process and the solid-liquid separation and washing process are the core steps connecting extraction and purification.

[0003] Secondary neutralization addresses the impurities remaining after primary neutralization. During primary neutralization, some soluble impurities in the fermentation broth may adsorb onto the surface of the calcium citrate precipitate, or incomplete reaction may cause local pH fluctuations, generating byproducts. If directly introduced into the subsequent acidolysis process, where sulfuric acid is used to reduce calcium citrate to citric acid, these impurities will enter the final product, leading to a decrease in citric acid purity and even affecting downstream applications. Therefore, secondary neutralization is necessary for further optimization: the calcium citrate precipitate obtained from primary neutralization is redispersed in water, and a small amount of citric acid is added to further react and dissolve the alkaline impurities (such as excess calcium carbonate) adsorbed on the precipitate surface, while simultaneously reducing pigment adsorption, laying the foundation for subsequent purification.

[0004] To control water and acid consumption in the chromatographic separation system, the residual citric acid in the remaining sugars was extracted using the traditional calcium salt method. This method not only ensured the yield of citric acid but also reduced the consumption of calcium carbonate and the output of calcium sulfate byproducts.

[0005] Patent application number CN201310744509.2 discloses "a method for purifying citric acid from citric acid fermentation broth". This technical solution uses an anion exchange resin chromatography system to perform chromatographic separation on citric acid fermentation broth to remove residual sugar and obtain purified citric acid. It has made some progress in the purification of citric acid. However, the remaining product contains a small amount of citric acid. Continuing to purify it by chromatography will increase the water and acid consumption of the chromatographic separation system.

[0006] In summary, while chromatography is more efficient for citric acid purification, the residue contains a small amount of citric acid. Further chromatographic purification would increase water and acid consumption in the chromatographic separation system. Therefore, a secondary neutralization reaction is proposed where the citric acid in the residual sugars from the chromatographic separation system undergoes a secondary neutralization reaction with the tricalcium slurry after primary neutralization and filtration to generate calcium hydrogen citrate. This reduces water consumption in the chromatographic separation system, increases the yield of citric acid, and combines chromatography with the traditional calcium salt method, providing a new direction for optimizing and upgrading the citric acid purification process. Utility Model Content

[0007] 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.

[0008] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0009] The purpose of this invention is to overcome the problems existing in the prior art and provide a citric acid secondary neutralization and vacuum filtration washing device. The device extracts citric acid from the residual sugars in the chromatographic separation system using the calcium salt method, and then performs a secondary neutralization reaction with the tricalcium slurry after the first neutralization and filtration to generate calcium hydrogen citrate. The device is then subjected to vacuum filtration and washing, which can reduce the water and acid consumption of the chromatographic separation system and increase the yield of citric acid.

[0010] To solve the above technical problems, this utility model provides a citric acid secondary neutralization and vacuum filtration washing device, including a dilute citric acid buffer tank 1101. The inlet of the dilute citric acid buffer tank 1101 is connected to the miscellaneous sugar and dilute citric acid discharge pipe G37 of the citric acid chromatography separation unit. The outlet of the dilute citric acid buffer tank 1101 is connected to the cold side inlet of a plate heat exchanger 1103 through a dilute citric acid transfer pump 1102. The hot side inlet of the plate heat exchanger 1103 is connected to a steam pipe G05. The hot side outlet of the plate heat exchanger 1103 is connected to a condensate tank 412 through a condensate return pipe G16. The cold side outlet of the plate heat exchanger 1103 is connected to the dilute acid inlet of the first secondary neutralization pot 1104. Multiple secondary neutralization pots 1104 are connected in series. The cake discharge port of the tricalcium vacuum belt filter 1001 is connected to the tricalcium slurry preparation tank 1011. The slurry water inlet of the tricalcium slurry preparation tank 1011 is connected to the condensate supply pipe G15. The outlet of the tricalcium slurry preparation tank 1011 is connected to the second secondary neutralization pot 1104 through the tricalcium slurry preparation pump 1012. The discharge port of the end secondary neutralization pot 1104 is connected to the inlet of the secondary neutralization variable frequency circulation pump 1105 and the secondary neutralization discharge pump 1106. The outlet of the secondary neutralization variable frequency circulation pump 1105 is connected to the return port of the first secondary neutralization pot 1104. The outlet of the secondary neutralization discharge pump 1106 is connected to the slurry distributor of the calcium hydrogen vacuum belt filter 1201.

[0011] Furthermore, the calcium hydrogen vacuum belt filter 1201 is provided with a feeding area, a filtration area, a washing and dehydration area and a cake discharge area in sequence along the filter cloth advancing direction, and the filtrate outlet below is connected to the inlet of the vacuum tank 1202 respectively. The exhaust port at the top of each vacuum tank 1202 is connected to the middle inlet of the gas-water separator 1203. The top of the gas-water separator 1203 is vented to the atmosphere through the vacuum pump 1204. The washing and dehydration zone is equipped with five vacuum tanks in sequence along the direction of filter cloth movement. The bottom outlets of the vacuum tank 1202-1, the first-stage vacuum tank 1202-2, the second-stage vacuum tank 1202-3, and the gas-water separator 1203 in the filtration zone are all connected to the inlet of the calcium hydrogen acid buffer tank 1205. The outlet of the calcium hydrogen acid buffer tank 1205 is connected to the calcium hydrogen acid pump 1206 and the mixed acid tank 901.

[0012] Furthermore, the outlet of the three-stage vacuum tank 1202-4 is connected to the first-stage calcium hydrogen acid tank 1207, and the bottom outlet of the first-stage calcium hydrogen acid tank 1207 is connected to the first-stage rinsing water inlet above the washing and dehydration zone through the first-stage calcium hydrogen acid pump 1208. The outlet of the fourth-stage vacuum tank 1202-5 is connected to the second-stage calcium hydrogen dilute acid tank 1209. The outlet of the second-stage calcium hydrogen dilute acid tank 1209 is connected to the second-stage rinsing water inlet above the washing and dehydration zone through the second-stage calcium hydrogen dilute acid pump 1210. The outlet of the five-stage vacuum tank 1202-6 is connected to the four-stage calcium hydrogen acid tank 1211. The bottom outlet of the four-stage calcium hydrogen acid tank 1211 is connected to the four-stage rinsing water inlet above the washing and dehydration zone through the four-stage calcium hydrogen acid pump 1212. The end of the calcium hydrogen vacuum belt filter 1201 is connected to the inlet of the calcium hydrogen washing water tank 1213. The outlet of the calcium hydrogen washing water tank 1213 is connected to the three-stage rinsing water inlet above the washing and dehydration zone through the calcium hydrogen washing water pump 1214. The five-stage rinsing water inlet above the washing and dehydration zone is connected to the condensate supply pipe G15.

[0013] Furthermore, the filter cake discharge port of the calcium hydrogen vacuum belt filter 1201 is connected to the calcium hydrogen slurry preparation tank 1215, the slurry water inlet of the calcium hydrogen slurry preparation tank 1215 is connected to the condensate supply pipe G15, and the bottom outlet of the calcium hydrogen slurry preparation tank 1215 is connected to the calcium hydrogen slurry buffer tank 1301 of the acidolysis unit through the calcium hydrogen slurry preparation pump 1216.

[0014] Compared to the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following: 1. Citric acid in the residual sugars of the chromatographic separation system is extracted by calcium salt method. It undergoes a secondary neutralization reaction with the tricalcium slurry after the first neutralization and filtration to generate calcium hydrogen citrate, which reduces the water and acid consumption of the chromatographic separation system and improves the yield of citric acid.

[0015] 2. To ensure stable acidity of the secondary neutralization discharge, a variable frequency pump is added to the discharge stage for circulation, and an online pH sensor is installed on the discharge pipeline to achieve precise control of the reaction process. By setting a certain circulation volume, the acidity in the three neutralization tanks is ensured to be uniform and stable, thus guaranteeing the normal operation of subsequent production.

[0016] 3. To prevent precipitate blockage, increase the diameter of the pipe connecting the three tanks in series, reduce the number of small bends in the pipes, and shorten the residence time of calcium citrate in the tanks.

[0017] 4. Countercurrent washing is used during vacuum filtration and washing to reduce the amount of washing water by utilizing the concentration gradient; a dual cleaning system of high-pressure water cleaning and back-blowing air is used at the tail end to deeply regenerate and unblock the pores of the filter cloth after vacuum filtration and washing, thereby extending the service life of the filter cloth, reducing production costs, and improving the recovery rate of citric acid products. Attached Figure Description

[0018] 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 This is a flowchart of the secondary neutralization unit in this utility model; Figure 2 This is a flowchart of the calcium hydrogen citrate vacuum filtration and washing unit in this utility model; Figure reference numerals: condensate tank 412; condensate pump 424; chromatographic column 801; mixed acid tank 901; Tricalcium phosphate vacuum belt filter 1001; Tricalcium phosphate slurry preparation tank 1011; Tricalcium phosphate slurry preparation pump 1012; 1101 dilute citric acid buffer tank; 1102 dilute citric acid transfer pump; 1103 plate heat exchanger; 1104 secondary neutralization pot; 1105 secondary neutralization variable frequency circulation pump; 1106 secondary neutralization discharge pump; Calcium hydrogen vacuum belt filter 1201; Vacuum tank 1202; Gas-water separator 1203; Vacuum pump 1204; Calcium hydrogen concentrated acid buffer tank 1205; Calcium hydrogen concentrated acid pump 1206; Primary calcium hydrogen dilute acid tank 1207; Primary calcium hydrogen dilute acid pump 1208; Secondary calcium hydrogen dilute acid tank 1209; Secondary calcium hydrogen dilute acid pump 1210; Quaternary calcium hydrogen dilute acid tank 1211; Quaternary calcium hydrogen dilute acid pump 1212; Calcium hydrogen cloth washing water tank 1213; Calcium hydrogen cloth washing water pump 1214; Calcium hydrogen slurry preparation tank 1215; Calcium hydrogen slurry preparation pump 1216. Calcium hydrogen slurry buffer tank 1301; Steam pipe G05; condensate supply pipe G15; condensate return pipe G16; miscellaneous sugar and dilute citric acid discharge pipe G37; calcium hydrogen concentrated acid pipe G38. 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, in the citric acid secondary neutralization and vacuum filtration washing device of this invention, the miscellaneous sugar outlet of each chromatographic column 801 is connected to the inlet of the dilute citric acid buffer tank 1101 through the miscellaneous sugar and dilute citric acid discharge pipe G37. The outlet of the dilute citric acid buffer tank 1101 is connected to the inlet of the dilute citric acid transfer pump 1102. The outlet of the dilute citric acid transfer pump 1102 is connected to the cold side inlet of the plate heat exchanger 1103. The hot side inlet of the plate heat exchanger 1103 is connected to the steam pipe G05. The hot side outlet of the plate heat exchanger 1103 is connected to the condensate tank through the condensate return pipe G16. 412 are connected; the cold side outlet of the plate heat exchanger 1103 is connected to the dilute acid inlet of the first secondary neutralization pot 1104, and multiple secondary neutralization pots 1104 are connected in series. The discharge port of the end secondary neutralization pot 1104 is connected to the inlet of the secondary neutralization variable frequency circulation pump 1105 and the secondary neutralization discharge pump 1106. The outlet of the secondary neutralization variable frequency circulation pump 1105 is connected to the reflux port of the first secondary neutralization pot 1104. An online pH sensor is installed on the discharge pipe of the secondary neutralization discharge pump 1106 and is connected to the slurry distributor of the calcium hydrogen vacuum belt filter 1201.

[0023] The chromatographic separation system generates citric acid from the residual sugars, which is discharged through the sugar and dilute citric acid discharge pipe G37 into the dilute citric acid buffer tank 1101. From there, it is pumped into the secondary neutralization vessel 1104 via the dilute citric acid transfer pump 1102. To accelerate the neutralization reaction and improve its efficiency, the dilute citric acid is heated to approximately 85-88°C before secondary neutralization by exchanging heat with steam on the hot side of the plate heat exchanger 1103. To control this heat exchange temperature, the steam regulating valve is interlocked with the temperature sensor TT-1103, which detects the temperature of the dilute citric acid.

[0024] The heated dilute citric acid is pumped into the first secondary neutralization vessel 1104. Three secondary neutralization vessels 1104 are connected in series. The dilute citric acid flow meter and regulating valve are interlocked with the level gauge LT-1104 on the secondary neutralization vessel. The level in the secondary neutralization vessel 1104 is controlled by adjusting the opening of the regulating valve. When the level in the first secondary neutralization vessel reaches approximately 30%, tricalcium citrate slurry from the primary neutralization unit is pumped into the second secondary neutralization vessel to begin the secondary neutralization reaction, producing calcium hydrogen citrate.

[0025] During the commissioning process, we found that the three-stage series secondary neutralization pot 1104 and the gravity flow pipe were prone to blockage, which led to unstable neutralization reaction and inability to stably control the acidity of the output.

[0026] To ensure stable acidity of the secondary neutralization output, a secondary neutralization variable frequency circulation pump 1105 is added at the discharge end to circulate the product. A certain amount of circulation back to the first secondary neutralization pot ensures stable acidity in all three neutralization tanks, guaranteeing stable production operation. Online pH sensors are added to the discharge pipes of the first and third secondary neutralization pots for precise control of the reaction process. To prevent precipitation and blockage, the series connection of the pipes between the three tanks is enlarged, and the number of small bends in the pipes is reduced to minimize the residence time of calcium citrate in the tanks. When the online detection shows that the pH value in the first secondary neutralization pot is 3.0~4.0 and the acidity in the third secondary neutralization pot is 3.0~4.5%, it indicates that the secondary neutralization reaction is complete, and the secondary neutralization discharge pump 1106 is started to discharge the product. To ensure continuous and stable discharge, a circulation rate of return material to discharge material of 5:1 is used. The calcium citrate discharged from the secondary neutralization discharge pump 1106 then enters the calcium hydride vacuum belt filter 1201 for filtration and washing.

[0027] like Figure 2 As shown, in the calcium dicalcium citrate vacuum filtration and washing unit, the calcium dicalcium vacuum belt filter 1201 is provided with a feeding area, a filtration area, a washing and dehydration area and a cake discharge area in sequence along the filter cloth advancing direction, and the filtrate outlet below is connected to the inlet of the vacuum tank 1202 respectively. The exhaust port at the top of each vacuum tank 1202 is connected to the middle inlet of the gas-water separator 1203. The top of the gas-water separator 1203 is vented to the atmosphere through the vacuum pump 1204. The washing and dehydration zone is equipped with five vacuum tanks in sequence along the direction of filter cloth advance. The bottom outlets of the vacuum tank 1202-1, the first-stage vacuum tank 1202-2, the second-stage vacuum tank 1202-3 and the gas-water separator 1203 in the filtration zone are all connected to the inlet of the calcium hydrogen acid buffer tank 1205. The outlet of the calcium hydrogen acid buffer tank 1205 is connected to the calcium hydrogen acid pump 1206 and the mixed acid tank 901. The outlet of the three-stage vacuum tank 1202-4 is connected to the first-stage calcium hydrogen acid tank 1207. The bottom outlet of the first-stage calcium hydrogen acid tank 1207 is connected to the first-stage rinsing water inlet above the washing and dehydration zone through the first-stage calcium hydrogen acid pump 1208. The outlet of the fourth-stage vacuum tank 1202-5 is connected to the second-stage calcium hydrogen dilute acid tank 1209. The outlet of the second-stage calcium hydrogen dilute acid tank 1209 is connected to the second-stage rinsing water inlet above the washing and dehydration zone through the second-stage calcium hydrogen dilute acid pump 1210. The outlet of the five-stage vacuum tank 1202-6 is connected to the four-stage calcium hydrogen acid tank 1211. The bottom outlet of the four-stage calcium hydrogen acid tank 1211 is connected to the four-stage rinsing water inlet above the washing and dehydration zone through the four-stage calcium hydrogen acid pump 1212. The end of the calcium hydrogen vacuum belt filter 1201 is connected to the inlet of the calcium hydrogen wash water tank 1213. The outlet of the calcium hydrogen wash water tank 1213 is connected to the three-stage rinsing water inlet above the washing and dehydration zone through the calcium hydrogen wash water pump 1214. The five-stage rinsing water inlet above the washing and dehydration zone is connected to the condensate supply pipe G15.

[0028] The filter cake discharge port of the calcium hydrogen vacuum belt filter 1201 is connected to the calcium hydrogen slurry preparation tank 1215. The slurry water inlet of the calcium hydrogen slurry preparation tank 1215 is connected to the condensate supply pipe G15. The bottom outlet of the calcium hydrogen slurry preparation tank 1215 is connected to the calcium hydrogen slurry buffer tank 1301 of the acidolysis unit through the calcium hydrogen slurry preparation pump 1216.

[0029] Tricalcium citrate slurry undergoes a secondary neutralization reaction with citric acid in residual sugars to produce calcium hydrogen citrate slurry. The slurry still contains a small amount of unneutralized citric acid and residual sugars. Therefore, it is necessary to perform solid-liquid separation using a calcium hydrogen vacuum belt filter 1201 to remove the citric acid and residual sugars from the calcium hydrogen citrate slurry and obtain pure calcium hydrogen citrate.

[0030] Feeding Zone: The calcium dicalcium citrate slurry generated from the secondary neutralization reaction flows into the slurry distributor of the calcium dicalcium vacuum belt filter 1201 at a stable flow rate through a flow meter and regulating valve, and is evenly distributed on the rotating filter cloth. The vacuum pump 1204 generates vacuum suction to form a vacuum chamber under the filter cloth, initially creating negative pressure. The calcium dicalcium citrate slurry permeates into the vacuum chamber through the filter cloth, and solid particles initially accumulate on the surface of the filter cloth to form an initial filter cake, which then enters the filtration zone.

[0031] Filtration Zone: The filter cloth, carrying the calcium hydride slurry, enters the main filtration zone with a high vacuum. Under continuous negative pressure, a large amount of liquid is drawn into the vacuum chamber, gradually increasing the thickness of the filter cake and compacting it. The vacuum chamber is connected to a vacuum pump via a pipe. The extracted filtrate waste sugar water is separated by the vacuum tank 1202-1 and the gas-liquid separator 1203 in the filtration zone, and then enters the calcium hydride concentrated acid buffer tank 1205. It is then pumped to the mixed acid tank 901 for neutralization via the calcium hydride concentrated acid pump 1206 and the calcium hydride concentrated acid pipe G38, while the gas is discharged by the vacuum pump. Since the filter cake still contains a small amount of residual sugar and citric acid, it needs to enter the washing and dehydration zone for further washing and dehydration.

[0032] Washing and Dehydration Zone: To ensure maximum washing efficiency and product recovery rate, a countercurrent washing method is adopted, utilizing the concentration gradient to reduce the amount of washing water used. To completely separate residual sugar and citric acid from the calcium dicalcium citrate filter cake, a five-stage countercurrent washing process is employed: stage five uses clean water, stage four uses stage five filtrate, stage three uses collected filter cloth washing water, stage two uses stage four filtrate, and stage one uses stage three filtrate, with the concentration of the filtrate increasing sequentially after washing. Condensate from condensate pump 424 is used as the fifth-stage clean water to wash the filter cake. The flow rate of clean water is controlled by adjusting the flow meter and regulating valve opening. Residual sugar and citric acid are completely washed away. Under vacuum, the filtrate, residual sugar, and citric acid are pumped together into the fifth-stage vacuum tank 1202-6. Since the concentration of residual sugar and citric acid in this filtrate is low, it can enter the fourth-stage calcium dicalcium acid tank 1211 as fourth-stage washing water, which is then pumped to the fourth-stage washing zone by the fourth-stage calcium dicalcium acid pump 1212 to wash the filter cake. The washed filtrate is pumped into the fourth-stage vacuum tank 1202-5, where the citric acid concentration increases. It then enters the second-stage calcium hydrogen dilute acid tank 1209 as secondary washing water. It is pumped into the secondary washing area by the second-stage calcium hydrogen dilute acid pump 1210 to wash the filter cake. The washed filtrate is pumped into the second-stage vacuum tank 1202-3, where the citric acid content is high. It flows into the calcium hydrogen concentrated acid buffer tank 1205 and is then pumped into the mixed acid tank 901 for primary neutralization via the calcium hydrogen concentrated acid pump 1206 and the calcium hydrogen concentrated acid pipe G38.

[0033] The thoroughly cleaned and partially dried filter cake (calcium citrate) enters the unloading area for discharge. After unloading, high-pressure water is introduced to clean the filter cloth, flowing into the calcium hydride cloth washing tank 1213. To recover the small amount of calcium hydride solid particles contained in the filter cloth water, this is used as tertiary washing water and pumped by the calcium hydride cloth washing pump 1214 to clean the calcium hydride filter cake. The small amount of calcium hydride solid particles are retained by the filter cloth, forming a filter cake. The filtrate contains a certain amount of citric acid and enters the primary calcium hydride dilute acid tank 1207 via the tertiary vacuum tank 1202-4 as primary washing water. This water is then pumped by the primary calcium hydride dilute acid pump 1208 to the primary washing area to clean the filter cake. The cleaned filtrate is pumped to the primary vacuum tank 1202-2. Since this filtrate has a high citric acid content, it enters the calcium hydride concentrated acid buffer tank 1205 and is then pumped to the mixed acid tank 901 via the calcium hydride concentrated acid pump 1206 and the calcium hydride concentrated acid pipe G38.

[0034] To ensure both washing effectiveness and water volume control during the washing process, this technology installs electromagnetic flow meters and regulating valves on each stage of the washing water pipeline. By controlling the opening of the regulating valves, the water volume at each stage is ensured to be uniform and stable.

[0035] Cake Discharge Area: The thoroughly cleaned and dried calcium dicalcium citrate filter cake enters the cake discharge area for unloading. The filter cake is automatically unloaded due to its own gravity and the assistance of a scraper. The calcium dicalcium citrate filter cake then falls into the calcium dicalcium slurry preparation tank 1215. After adding condensate from the condensate pump 424 and the condensate supply pipe G15 for slurry preparation, it is pumped into the calcium dicalcium slurry buffer tank 1301 of the subsequent acidolysis unit via the calcium dicalcium slurry preparation pump 1216.

[0036] In order to deeply unclog the filter cloth pores, high-pressure water and compressed air are introduced into the filter cake cleaning area for deep cleaning, so as to achieve deep regeneration of the filter cloth and unclogging of pores, and ensure the continuous and stable filtration efficiency.

[0037] 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 device for citric acid secondary neutralization and vacuum filtration washing, comprising a dilute citric acid buffer tank (1101), characterized in that: The inlet of the dilute citric acid buffer tank (1101) is connected to the discharge pipe (G37) of the miscellaneous sugars and dilute citric acid of the citric acid chromatography separation unit. The outlet of the dilute citric acid buffer tank (1101) is connected to the cold side inlet of the plate heat exchanger (1103) through the dilute citric acid transfer pump (1102). The hot side inlet of the plate heat exchanger (1103) is connected to the steam pipe (G05). The hot side outlet of the plate heat exchanger (1103) is connected to the condensate tank (412) through the condensate return pipe (G16). The cold side outlet of the plate heat exchanger (1103) is connected to the dilute acid inlet of the first secondary neutralization pot (1104). Multiple secondary neutralization pots (1104) are connected in series. The filter cake discharge port of the tricalcium vacuum belt filter (1001) is connected to the tricalcium slurry preparation tank (1011). The slurry water inlet of the tricalcium slurry preparation tank (1011) is connected to the condensate supply pipe (G15). The outlet of the tricalcium slurry preparation tank (1011) is connected to the second secondary neutralization pot (1104) through the tricalcium slurry preparation pump (1012). The discharge port of the end secondary neutralization pot (1104) is connected to the inlet of the secondary neutralization variable frequency circulation pump (1105) and the secondary neutralization discharge pump (1106). The outlet of the secondary neutralization variable frequency circulation pump (1105) is connected to the return port of the first secondary neutralization pot (1104). The outlet of the secondary neutralization discharge pump (1106) is connected to the slurry distributor of the calcium hydrogen vacuum belt filter (1201).

2. The device for secondary neutralization and vacuum filtration washing of citric acid according to claim 1, characterized in that: The calcium hydrogen vacuum belt filter (1201) is provided with a feeding area, a filtration area, a washing and dehydration area and a cake discharge area in sequence along the filter cloth forward direction, and the filtrate outlet below is connected to the inlet of the vacuum tank (1202). The exhaust port at the top of each vacuum tank (1202) is connected to the middle inlet of the gas-water separator (1203). The top of the gas-water separator (1203) is vented to the atmosphere through a vacuum pump (1204). The washing and dehydration zone is equipped with five vacuum tanks in sequence along the direction of filter cloth movement. The bottom outlets of the vacuum tank (1202-1), the first-stage vacuum tank (1202-2), the second-stage vacuum tank (1202-3), and the gas-water separator (1203) in the filtration zone are all connected to the inlet of the calcium hydrogen acid buffer tank (1205). The outlet of the calcium hydrogen acid buffer tank (1205) is connected to the calcium hydrogen acid pump (1206) and the mixed acid tank (901).

3. The device for secondary neutralization and vacuum filtration washing of citric acid according to claim 2, characterized in that: The outlet of the three-stage vacuum tank (1202-4) is connected to the first-stage calcium hydrogen acid tank (1207), and the bottom outlet of the first-stage calcium hydrogen acid tank (1207) is connected to the first-stage rinsing water inlet above the washing and dehydration zone through the first-stage calcium hydrogen acid pump (1208). The outlet of the fourth-stage vacuum tank (1202-5) is connected to the second-stage calcium hydrogen acid tank (1209), and the outlet of the second-stage calcium hydrogen acid tank (1209) is connected to the second-stage rinsing water inlet above the washing and dehydration zone through the second-stage calcium hydrogen acid pump (1210). The outlet of the five-stage vacuum tank (1202-6) is connected to the four-stage calcium hydrogen acid tank (1211). The bottom outlet of the four-stage calcium hydrogen acid tank (1211) is connected to the four-stage rinsing water inlet above the washing and dehydration zone through the four-stage calcium hydrogen acid pump (1212). The end washing water outlet of the calcium hydrogen vacuum belt filter (1201) is connected to the inlet of the calcium hydrogen washing water tank (1213), and the outlet of the calcium hydrogen washing water tank (1213) is connected to the three-stage rinsing water inlet above the washing and dehydration zone through the calcium hydrogen washing water pump (1214). The five-stage rinsing water inlet above the washing and dehydration zone is connected to the condensate supply pipe (G15).

4. The device for secondary neutralization and vacuum filtration washing of citric acid according to claim 3, characterized in that: The filter cake discharge port of the calcium hydrogen vacuum belt filter (1201) is connected to the calcium hydrogen slurry preparation tank (1215). The slurry water inlet of the calcium hydrogen slurry preparation tank (1215) is connected to the condensate supply pipe (G15). The bottom outlet of the calcium hydrogen slurry preparation tank (1215) is connected to the calcium hydrogen slurry buffer tank (1301) of the acidolysis unit through the calcium hydrogen slurry preparation pump (1216).

Images