Multistage continuous condensation tower for sorbic acid production

Abstract

The invention discloses a multi-stage continuous condensation tower for sorbic acid production, and relates to the technical field of sorbic acid preparation, the multi-stage continuous condensation tower comprises multiple stages of sedimentation reaction towers, the multiple stages of sedimentation reaction towers are arranged up and down, and the upper and lower stages of sedimentation reaction towers are communicated with each other. The multistage continuous condensation tower for sorbic acid production achieves the purposes of continuous production, stable quality and no residual materials.

Description

Technical Field

[0001] The invention relates to the technical field of sorbic acid preparation, in particular to a multi-stage continuous condensation tower for sorbic acid production. Background Art

[0002] Sorbic acid preservatives are non-toxic, highly safe and have good preservative effects. They are internationally recognized as the best food preservatives. So far, there are more than ten process routes for the synthesis of sorbic acid, but not many processes are suitable for industrialization. Industrial production practice has proved that the most successful and economical process route is the "acetic acid cracking-ethylene ketone / crotonaldehyde polycondensation-polyester acidolysis crystallization" process route. Among them, the "ethylene ketone / crotonaldehyde polycondensation" process is the key to ensuring product quality and process economy. At present, an intermittent condensation reaction system is used in industrial production. The condensation reaction system includes a condensation kettle, a condensation tower, a cooler and a condensation liquid circulation pump.

[0003] In the existing industrial condensation reaction system, during the production operation, the prepared fresh crotonaldehyde raw material liquid is first pumped into the condensation kettle, the circulation pump is turned on, and the raw material liquid is sent to the top of the condensation tower through the pipeline. After passing through the liquid distribution plate, it flows through several packing layers from top to bottom. At the same time, it contacts the ethylene ketone gas entering from the bottom of the condensation tower in the packing layer in reverse, and the condensation reaction begins. The reaction tail gas flows out from the top outlet of the tower and enters the tail gas absorption system. The reaction heat is transferred to the heat exchange coil on the tower wall through the metal filler. After the fresh raw material liquid undergoes condensation reaction through several packing layers, it flows into the condensation kettle at the bottom of the tower. The condensation liquid then enters the top of the condensation tower through the circulation pump. After several kettle-tower cycles, the transmittance increase of the condensation liquid in the condensation kettle is detected. When the increase reaches the end point of the reaction, the ethylene ketone feed is closed, and the liquid phase product is pumped into the high-level tank, and then distilled to remove low-molecular impurities.

[0004] The condensation reaction system in the prior art solution adopts intermittent operation, which has the following disadvantages:

[0005] 1) The production operation is complicated. Due to the intermittent operation, the crotonaldehyde content in the condensation liquid is different at different cycle times, and the amount of ketene consumed is also different. The ketene flow rate needs to be adjusted at any time to achieve the best ratio. This leads to high tension and heavy workload for on-site and central control operators, and adjustments are made throughout the entire reaction process.

[0006] 2) Due to the intermittent operation, the heat release of the reaction changes at any time, and the operator also needs to adjust the flow of frozen brine in the cooling coils of the condensation tower and the condensation kettle at any time to achieve stable temperature control; this also leads to high tension and heavy workload for the on-site and central control operators, and adjustments are made throughout the entire reaction process;

[0007] 3) Due to the above-mentioned intermittent operation characteristics, the production process is heavily dependent on the operating experience and habits of on-site and central control operators, resulting in the difficulty in stabilizing product quality. The quality of each batch of products fluctuates, bringing challenges to subsequent quality control;

[0008] 4) When using intermittent production, after the previous batch of materials is discharged, there is still a small amount of condensation products and solvents remaining in the equipment, pipelines and packings, which are prone to oxidation and deterioration, and are mixed into the next batch of reaction raw materials, resulting in a decrease in product quality and an increase in the amount of over-reaction by-products.

[0009] How to develop a multi-stage continuous condensation tower for sorbic acid production to achieve the goals of continuous production, stable quality and no residual materials has become a technical problem that needs to be solved urgently by technicians in this field. Summary of the invention

[0010] The purpose of the present invention is to provide a multi-stage continuous condensation tower for sorbic acid production to solve the problems listed in the background technology.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0012] The invention discloses a multi-stage continuous condensation tower for producing sorbic acid, comprising a multi-stage sedimentation reaction tower, wherein the multi-stage sedimentation reaction towers are arranged up and down, and the adjacent upper and lower sedimentation reaction towers are connected to each other.

[0013] Preferably, the interior of the sedimentation reaction tower includes a condensation liquid injection zone, a micro-droplet sedimentation reaction zone, a cooling zone and an inlet and outlet zone, and the condensation liquid injection zone, the micro-droplet sedimentation reaction zone, the cooling zone and the inlet and outlet zone are arranged in sequence from top to bottom and are interconnected.

[0014] Preferably, the condensation liquid injection area is equipped with a micro-droplet injection device, and the side wall of the condensation liquid injection area is connected to a tail gas port;

[0015] The nozzle of the micro-droplet injection device coincides with the central axis of the sedimentation reaction tower, and the nozzle is located below the tail gas outlet.

[0016] Preferably, the cooling zone is equipped with a spiral plate heat exchanger, the upper end of the spiral plate heat exchanger is connected to a cooling water outlet, and the lower end of the spiral plate heat exchanger is connected to a cooling water inlet.

[0017] The spiral plate heat exchanger is communicated with the micro-droplet settling reaction zone and the material inlet and outlet zones respectively.

[0018] Preferably, an air inlet and a liquid discharge port are respectively connected on the side walls of the material inlet and outlet zones, and the air inlet is located above the liquid discharge port.

[0019] Preferably, the liquid discharge port is connected via a storage tank located between the upper and lower sedimentation reaction towers, and the storage tank is connected to the micro-droplet injection device of the next stage via a pump.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] The invention discloses a multi-stage continuous condensation tower for sorbic acid production, which realizes the technical idea of ​​continuous production, optimizes and determines the ketene flow rate of each tower stage, and reduces the ketene flow rate adjustment range from 50%-200% under the original intermittent operation conditions to 5%-10% under the continuous operation conditions; reduces the ketene flow rate adjustment frequency from 0.3 times / minute under the original intermittent operation conditions to 0.03 times / minute under the continuous operation conditions, greatly reducing the adjustment range and adjustment frequency of the ketene flow rate, and realizing online automatic control and adjustment of the ketene flow rate;

[0022] In view of the problem that the flow rate of frozen brine in the condensation tower and the condensation kettle needs to be adjusted at any time to maintain the optimal reaction temperature during intermittent operation, the present invention proposes a technical idea of ​​using a multi-stage continuous condensation tower to achieve continuous production, optimizes and determines the flow rate of frozen brine at each tower level, and reduces the adjustment range of the frozen brine flow rate from 20%-300% under the original intermittent operation conditions to 8%-12% under the continuous operation conditions; the flow rate adjustment frequency of the frozen brine is reduced from 0.5 times / minute under the original intermittent operation conditions to 0.02 times / minute under the continuous operation conditions, which greatly reduces the adjustment range and adjustment frequency of the frozen brine flow rate, and realizes online automatic control and adjustment of the frozen brine flow rate;

[0023] In view of the problem that product quality is heavily dependent on operators and product quality fluctuates during intermittent operation, the present invention proposes a technical idea of ​​using a multi-stage continuous condensation tower to achieve continuous production, optimizes and fixes the operating parameters of each tower stage, and realizes online automatic control and adjustment of the operating parameters throughout the process; the product qualification rate is increased from 90% under the original intermittent operation conditions to 99.3% under the continuous operation conditions, achieving the purpose of stable product quality;

[0024] In order to solve the problems of deterioration and over-reaction of residual materials from the previous batch during intermittent operation, the present invention proposes a technical idea of ​​using a multi-stage continuous condensation tower to achieve continuous production, thereby achieving continuous operation of the condensation reaction and the purpose of no residual materials in the equipment and pipelines. The impact of residual materials from the previous batch on product quality is reduced from 1.2% under the original intermittent operation conditions to 0% under continuous operation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 The present invention is a schematic diagram of a multi-stage continuous condensation tower for producing sorbic acid.

[0027] Explanation of the reference numerals: 1. exhaust gas outlet; 2. micro-droplet injection device; 3. micro-droplet sedimentation reaction zone; 4. spiral plate heat exchanger; 5. cooling water outlet; 6. air inlet; 7. cooling water inlet; 8. drain outlet; 9. storage tank; 10. pump. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. 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.

[0029] like Figure 1 As shown, a multi-stage continuous condensation tower for sorbic acid production includes 2-8 stages of sedimentation reaction towers, wherein the 2-8 stages of sedimentation reaction towers are arranged up and down, and the upper and lower ends of the sedimentation reaction towers are fixedly connected to each other by bolt assemblies, and the upper and lower stages of the sedimentation reaction towers are interconnected, so as to ensure that the condensation liquid after the reaction of the upper stage of the sedimentation reaction tower can enter the lower stage of the sedimentation reaction tower to continue to participate in the reaction, thereby realizing continuous production of the condensation reaction, optimizing and fixing the operating parameters of each tower stage, realizing online automatic control and adjustment of the operating parameters throughout the process, reducing manual intervention to realize automatic control, avoiding that the product quality is seriously dependent on the operator during intermittent operation, and achieving the purpose of stable product quality.

[0030] Specifically, the interior of the sedimentation reaction tower includes a condensation liquid injection zone, a micro-droplet sedimentation reaction zone 3, a cooling zone and an inlet and outlet zone. The condensation liquid injection zone, the micro-droplet sedimentation reaction zone 3, the cooling zone and the inlet and outlet zone are arranged in sequence from top to bottom and are interconnected.

[0031] Specifically, the condensation liquid injection area is equipped with a micro-droplet injection device 2, and the side wall of the condensation liquid injection area is connected with an exhaust port 1;

[0032] The nozzle of the micro-droplet injection device 2 coincides with the central axis of the sedimentation reaction tower, and the nozzle is located below the tail gas port 1. After the condensation liquid is sprayed by the micro-droplet injection device, the condensation liquid forms a large number of micro-droplets and enters the droplet sedimentation reaction zone 3, thereby increasing the gas-liquid contact area of ​​the condensation reaction and accelerating the reaction rate.

[0033] The side walls of the inlet and outlet zones are connected with an air inlet 6 and a liquid discharge port 8, respectively. The air inlet 6 is located above the liquid discharge port 8. The cooling zone is equipped with a spiral plate heat exchanger 4. The upper end of the spiral plate heat exchanger 4 is connected with a cooling water outlet 5. The lower end of the spiral plate heat exchanger 4 is connected with a cooling water inlet 7. The setting of the multi-stage sedimentation reaction tower can greatly reduce the adjustment range and adjustment frequency of the frozen brine flow of the spiral plate heat exchanger, and can realize online automatic control and adjustment of the frozen brine flow;

[0034] Furthermore, ketene enters from the air inlet 6 and realizes the technical idea of ​​continuous production through multiple tower stages. The ketene flow rate of the corresponding tower stage is optimized and determined at each tower stage, and the flow adjustment range of ketene is reduced from 50%-200% under the original intermittent operation conditions to 5%-10% under the continuous operation conditions; the flow adjustment frequency of ketene is reduced from 0.3 times / minute under the original intermittent operation conditions to 0.03 times / minute under the continuous operation conditions, which greatly reduces the adjustment range and frequency of the ketene flow rate, realizes the online automatic control and adjustment of the ketene flow rate, makes the fluctuation of product quality smaller, and is conducive to ensuring the production quality of the product;

[0035] The spiral plate heat exchanger 4 is connected to the micro-droplet settling reaction zone 3 and the inlet and outlet zones respectively, and the discharge port 8 is connected to the micro-droplet injection device 2 of the next stage through a storage tank 9 and a pump 10 located between the upper and lower sedimentation reaction towers. Furthermore, the spiral plate heat exchanger has the advantages of small size, compact equipment, high heat transfer efficiency, and low metal consumption;

[0036] During operation, the condensation liquid is sprayed into the droplet settling reaction zone 3 of the first-stage settling reaction tower from the droplet spraying device 2 of the first-stage settling reaction tower. Under the action of gravity, the droplets settle downward from the top of the droplet settling reaction zone 3 of the first-stage settling reaction tower, and form a countercurrent contact with the ketene gas entering from the lower air inlet 6 of the first-stage settling reaction tower, and a condensation reaction occurs rapidly. After the reaction heat is cooled by the micro-liquid spiral plate heat exchanger 4 of the first-stage settling reaction tower, the droplets settle to the bottom of the first-stage settling reaction tower and flow out from the discharge port 8 of the first-stage settling reaction tower into the outlet storage tank 9 of the first-stage settling reaction tower.

[0037] Subsequently, the condensed liquid after the reaction enters the micro-droplet injection device 2 of the second-stage sedimentation reaction tower from the storage tank 9 between the first-stage sedimentation reaction tower and the second-stage sedimentation reaction tower after being pressurized by the pump 10, and forms a large number of micro-droplets in the droplet sedimentation reaction zone 3 of the second-stage sedimentation reaction tower. Subsequently, the micro-droplets in the droplet sedimentation reaction zone 3 form countercurrent contact with the ketene gas entering from the air inlet 6 below the second-stage sedimentation reaction tower under the action of gravity, and a condensation reaction occurs rapidly. After the reaction heat is cooled by the micro-liquid spiral plate heat exchanger 4 below the second-stage sedimentation reaction tower, the condensed liquid flows out from the discharge port 8 below the second-stage sedimentation reaction tower to the storage tank 9 between the second-stage sedimentation reaction tower and the third-stage sedimentation reaction tower;

[0038] By analogy, the condensation liquid obtains qualified condensation products after passing through 2-8 stage sedimentation reaction towers and enters into storage tanks to be processed by subsequent distillation process. Thus, the continuous production of condensation reaction is completed. There is no residual material in the equipment and pipelines. The influence of residual materials from the previous batch on product quality is reduced from 1.2% under the original intermittent operation conditions to 0% under the continuous operation conditions. At the same time, online automatic control and adjustment of the whole operation parameters are realized, and the qualified rate of products is increased from 90% under the original intermittent operation conditions to 99.3% under the continuous operation conditions, thus achieving the goal of stable product quality.

[0039] Embodiment 1

[0040] In a multi-stage continuous condensation tower with an inner diameter of 800mm, a single-stage micro-droplet settling reaction zone height of 1200mm, and 8-stage micro-droplet settling reaction zones, gas-liquid countercurrent operation is used, and the condensation liquid raw material volume is 150m 3 , condensation liquid flow rate 100m 3 / hr, ketene gas enters from the inlet of the 8th stage condensation tower, and enters the 7th to 1st stage condensation towers in countercurrent, with a total ketene flow rate of 3000m 3 / hr, after 1.5 hours of reaction time, the value of the reaction product increased to 283, the product reached the qualified standard, and the reaction was terminated;

[0041] In a conventional packed condensation tower with an inner diameter of 800 mm and a packing layer height of 9600 mm, the amount of condensation liquid raw material is 150 m3. 3 , condensation liquid circulation flow rate 100m 3 / hr, the reaction time takes 18.0 hours to complete. The use of a micro-droplet settling condensation tower shortens the reaction time by 91.6%.

[0042] Embodiment 2

[0043] In a multi-stage continuous condensation tower with an inner diameter of 800 mm, a single-stage micro-droplet settling reaction zone height of 4800 mm, and a two-stage micro-droplet settling reaction zone, gas-liquid countercurrent operation is used, and the condensation liquid raw material volume is 150m 3 , liquid phase circulation flow rate 100m3 / hr, ketene gas enters from the air inlet of the second stage condensation tower and enters the first stage condensation tower in a countercurrent manner. The total flow rate of ketene is 2000m 3 / hr, the adjustment range in production is 1900~2200m 3 / hr, the flow rate of ethylene ketone is adjusted in the range of 5-10%; in order to maintain a stable flow rate, the flow rate of ethylene ketone needs to be dynamically adjusted during production, and the adjustment frequency is 0.03 times / minute. After the reaction is completed, the product meets the qualified standard;

[0044] In a conventional packed condensation tower with an inner diameter of 800 mm and a packing layer height of 9600 mm, the ketene flow rate increases from the initial 1500 m 3 / hr, and then continue to adjust and increase the flow rate. After 10 minutes, the flow rate increases to 3000m 3 / hr, the ketene flow rate adjustment range is 200%; near the end of the reaction, the ketene flow rate needs to be adjusted from 1500m 3 / hr adjusted to 750m 3 / hr, the flow adjustment range of ketene is 50%. In order to ensure the normal progress of the reaction, the flow of ketene needs to be dynamically adjusted continuously during production, and the adjustment frequency is 0.3 times / minute. It can be seen that the use of multi-stage continuous condensation towers greatly reduces the adjustment range and frequency of ketene flow, and realizes online automatic control and adjustment of ketene flow.

[0045] Embodiment 3

[0046] In a multi-stage continuous condensation tower with an inner diameter of 800mm, a single-stage micro-droplet settling reaction zone height of 1200mm, and 8-stage micro-droplet settling reaction zones, gas-liquid countercurrent operation is used, and the condensation liquid raw material volume is 150m 3 , condensation liquid flow rate 100m 3 / hr, ketene gas enters from the air inlet of the 8th stage condensation tower, and enters the 7th to 1st stage condensation towers in countercurrent, with a total ketene flow rate of 3000m 3 / hr; the required flow rate of -25℃ chilled brine for the first condensation tower is 20m 3 / hr, the adjustment range in production is 18.4~22.4m 3 / hr, the flow rate of the frozen brine is adjusted in the range of 8-12%. In order to keep the reaction temperature stable, the flow rate of the frozen brine needs to be dynamically adjusted during production, and the adjustment frequency is 0.02 times / minute;

[0047] In a conventional packed condensation tower with an inner diameter of 800 mm and a packing layer height of 9600 mm, the flow rate of the frozen brine increases from the initial 50 m 3 / hr, and then continue to adjust and increase the flow rate. After 30 minutes, the flow rate increases to 200m 3 / hr, the flow rate of the chilled brine can be adjusted within a range of 300%; near the end of the reaction, the flow rate of the chilled brine needs to be adjusted from 50m / hr to 3 / hr adjusted to 40m 3 / hr, the flow adjustment range of ethylene ketone is 20%. In order to ensure the normal reaction, the flow of frozen brine needs to be dynamically adjusted continuously during production, and the adjustment frequency is 0.5 times / minute. It can be seen that the use of multi-stage continuous condensation towers greatly reduces the adjustment range and frequency of the flow of frozen brine, and realizes online automatic control and adjustment of frozen brine.

[0048] Embodiment 4

[0049] In a multi-stage continuous condensation tower with an inner diameter of 800mm, a single-stage micro-droplet settling reaction zone height of 1600mm, and a 6-stage micro-droplet settling reaction zone, gas-liquid countercurrent operation is used, and the condensation liquid raw material volume is 30,000m 3 , condensation liquid flow rate 100m 3 / hr, ketene gas enters from the inlet of the 6th stage condensation tower, and enters the 5th to 1st stage condensation towers in countercurrent, with a total ketene flow rate of 3000m 3 / hr, the reaction was completed after 100 hours. After long-term operation assessment, the average value-added of the reaction product was 287, the transmittance of the subsequent products met the standards, and the total qualified rate of the products was 99.3%;

[0050] In a conventional packed condensation tower with an inner diameter of 800 mm and a packing layer height of 9600 mm, the amount of condensation liquid raw material is 3000 m3. 3 , condensation liquid circulation flow rate 100m 3 / hr, the reaction was completed in 20 batches, the reaction time of a single batch was 18 hours, the quality fluctuations between batches were large, and the product qualification rate was 90%. It can be seen that in order to solve the problem that the product quality is seriously dependent on the operator and the product quality fluctuates during intermittent operation, a technical idea of ​​using a multi-stage continuous condensation tower to achieve continuous production was adopted, the operating parameters of each tower level were optimized and fixed, and the operating parameters were automatically controlled and adjusted online throughout the process. The product qualification rate was greatly improved, and the purpose of stable product quality was achieved.

[0051] Embodiment 5

[0052] In a multi-stage continuous condensation tower with an inner diameter of 800 mm, a single-stage micro-droplet settling reaction zone height of 1200 mm, and 8-stage micro-droplet settling reaction zones, gas-liquid countercurrent operation is used, and the condensation liquid flow rate is 100m 3 / hr, total ketene flow rate 3000m 3 / hr. After long-term operation assessment, the continuous operation of the condensation reaction was achieved, and the amount of residual materials in the equipment and pipelines during the production process was zero.

[0053] In a conventional packed condensation tower with an inner diameter of 800 mm and a packing layer height of 9600 mm, the amount of condensation liquid raw material is 150 m3. 3 , condensation liquid circulation flow rate 100m 3 / hr, after the first batch of reaction is finished, the material discharging operation is carried out. After the discharging is completed, the residual materials of the first batch of reactants in the pipeline, valves and packing are collected, analyzed and weighed. The mass of the residual materials accounts for about 1.2% of the total mass of the reactants. The residual materials become black and sticky as the residual time increases. The analysis shows that there are a lot of oxidation by-products. In the intermittent operation, the residual materials of the previous batch will affect the quality of the next batch of products. It can be seen that the use of multi-stage continuous condensation towers effectively avoids the influence of the residual materials of the previous batch on the product quality in the intermittent operation.

[0054] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0055] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-stage continuous condensation tower for sorbic acid production, characterized in that: It comprises a multi-stage sedimentation reaction tower, wherein the multi-stage sedimentation reaction tower is arranged up and down, and the upper and lower sedimentation reaction towers are connected with each other.

2. A multi-stage continuous condensation tower for sorbic acid production according to claim 1, characterized in that: The interior of the sedimentation reaction tower includes a condensation liquid injection zone, a micro-droplet sedimentation reaction zone (3), a cooling zone and an inlet and outlet zone. The condensation liquid injection zone, the micro-droplet sedimentation reaction zone (3), the cooling zone and the inlet and outlet zone are arranged in sequence from top to bottom and are interconnected.

3. A multi-stage continuous condensation tower for sorbic acid production according to claim 2, characterized in that: The condensation liquid spraying area is equipped with a micro-droplet spraying device (2), and the side wall of the condensation liquid spraying area is connected to a tail gas port (1); The nozzle of the micro-droplet injection device (2) coincides with the central axis of the sedimentation reaction tower, and the nozzle is located below the tail gas outlet (1).

4. A multi-stage continuous condensation tower for sorbic acid production according to claim 3, characterized in that: The cooling zone is equipped with a spiral plate heat exchanger (4), the upper end of the spiral plate heat exchanger (4) is connected to a cooling water outlet (5), and the lower end of the spiral plate heat exchanger (4) is connected to a cooling water inlet (7); The spiral plate heat exchanger (4) is respectively connected to the micro-droplet settling reaction zone (3) and the material inlet and outlet zones.

5. A multi-stage continuous condensation tower for sorbic acid production according to claim 4, characterized in that: An air inlet (6) and a liquid discharge port (8) are respectively connected on the side walls of the material inlet and outlet zones, and the air inlet (6) is located above the liquid discharge port (8).

6. A multi-stage continuous condensation tower for sorbic acid production according to claim 5, characterized in that: The liquid discharge port (8) is connected via a storage tank (9) located between the upper and lower sedimentation reaction towers, and the storage tank (9) is connected to the micro-droplet injection device (2) of the next stage via a pump (10).

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