A propionaldehyde synthesis system and method

Abstract

The application provides a propionaldehyde synthesis system and method, which comprises the following steps: 1) a raw material system comprising ethylene, carbon monoxide and hydrogen is reacted to obtain a gas phase product comprising propionaldehyde; 2) after the gas phase product is subjected to cooling treatment, a propionaldehyde liquid phase crude product and residual gas phase raw material are obtained, and the cooling treatment comprises internal cooling medium treatment and first external cooling medium treatment in sequence; 3) the propionaldehyde liquid phase crude product is subjected to stripping treatment by using synthesis gas raw material to obtain propionaldehyde and synthesis gas raw material after stripping; wherein the residual gas phase raw material and / or the synthesis gas raw material after stripping participates in the internal cooling medium treatment as an internal cooling medium. The propionaldehyde synthesis method can reduce the amount of first external cooling medium refrigeration water by subjecting the gas phase product to internal cooling medium treatment, thereby reducing energy consumption and production cost.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and particularly relates to a propionaldehyde synthesis system and method. Background Technology

[0002] Propanal is an important raw material for fine chemicals, mainly used in the production of intermediates such as n-propanol, propionic acid, trimethylolethane, and methyl methacrylate (MMA), and further used in the production of alkyd resins, pesticides, herbicides, insecticides, and PMMA (polymethyl methacrylate). It is also widely used in the production of fine chemicals in coatings, plastics, food, textiles, feed, and rubber additives. In recent years, the demand for propanal products in both domestic and international markets has been continuously increasing.

[0003] Among existing methods for preparing propionaldehyde, the hydroformylation of ethylene to propionaldehyde is the most widely used process in industrial production due to its low equipment cost and stable operating conditions. The hydroformylation of ethylene to propionaldehyde (also known as the carbonylation synthesis of propionaldehyde) is a process that uses ethylene, carbon monoxide, and hydrogen as raw materials, and, under the action of a catalyst (most industrial plants currently use rhodium-based catalysts), undergoes a hydroformylation reaction under specific temperature and pressure conditions to synthesize propionaldehyde.

[0004] The synthesis of propionaldehyde by ethylene hydroformylation can be divided into gas-phase circulation and liquid-phase circulation methods. The liquid-phase circulation method involves circulating the solvent containing the catalyst, requiring separation of the catalyst from the reactants. The gas-phase circulation method, on the other hand, leaves the catalyst and reaction solvent in the reactor, with the reaction products carried out through gas-phase circulation, eliminating the need for catalyst-reactant separation and reducing catalyst loss. In the conventional gas-phase circulation method, the gas-phase reaction products are condensed only through a two-stage heat exchange process involving circulating water and chilled water. Therefore, it consumes large amounts of circulating and chilled water, resulting in high energy consumption and production costs. Summary of the Invention

[0005] The main objective of this invention is to provide a method for synthesizing propionaldehyde that can reduce the amount of circulating water and chilled water used, thereby reducing energy consumption and production costs.

[0006] The present invention also provides a propionaldehyde synthesis system, which can reduce the amount of circulating water and chilled water used to synthesize propionaldehyde, thereby reducing energy consumption and production costs.

[0007] In a first aspect, the present invention provides a method for synthesizing propionaldehyde, comprising the following steps:

[0008] 1) A feed system including ethylene, carbon monoxide and hydrogen reacts to produce gaseous products including propionaldehyde.

[0009] 2) After the gaseous product is cooled, a crude liquid product of propionaldehyde and the remaining gaseous raw material are obtained. The cooling process includes internal cooling medium treatment and a first external cooling medium treatment in sequence.

[0010] 3) The crude liquid product of propionaldehyde is stripped using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock.

[0011] The remaining gaseous feedstock and / or the stripped syngas feedstock are used as internal cooling media in the internal cooling medium treatment.

[0012] In the propionaldehyde synthesis method described above, the heated internal cooling medium obtained after treatment with the internal cooling medium is used as a raw material in the reaction.

[0013] In the propionaldehyde synthesis method described above, the internal cooling medium treatment includes a first internal cooling medium treatment and a second internal cooling medium treatment. The remaining gaseous raw material participates in the first internal cooling medium treatment as the first internal cooling medium, and the stripped syngas raw material participates in the second internal cooling medium treatment as the second internal cooling medium.

[0014] In the propionaldehyde synthesis method described above, the first internal cooling medium treatment includes N first internal cooling medium sub-treatments, wherein the remaining gaseous raw material, as the first internal cooling medium, sequentially participates in the N first internal cooling medium sub-treatments, and the flow direction of the remaining gaseous raw material is opposite to the flow direction of the gaseous product; and / or,

[0015] The second internal cooling medium treatment includes M second internal cooling medium sub-treatments, wherein the stripped syngas feedstock serves as the second internal cooling medium and participates in the M second internal cooling medium sub-treatments in sequence, and the flow direction of the stripped syngas feedstock is opposite to the flow direction of the gas phase products.

[0016] Where N≥1, M≥1.

[0017] In the propionaldehyde synthesis method described above, N=2 and M=2;

[0018] The cooling process includes, in sequence, a first internal cooling medium sub-process, a first second internal cooling medium sub-process, a second first internal cooling medium sub-process, a second second internal cooling medium sub-process, and a first external cooling medium process.

[0019] In the propionaldehyde synthesis method described above, the cooling process further includes a second external cooling medium treatment, which is located between a first second internal cooling medium sub-treatment and a second first internal cooling medium sub-treatment.

[0020] In a second aspect, the present invention also provides a propionaldehyde synthesis system, comprising: a reaction unit, a cooling unit and a stripping unit;

[0021] The cooling unit includes an internal cooler and a first external cooler in sequence;

[0022] The gas phase outlet of the reaction unit is connected to the material inlet of the internal cooler, the material outlet of the internal cooler is connected to the material inlet of the first external cooler, the liquid phase outlet of the first external cooler is connected to the liquid phase inlet of the stripping unit, and the gas phase outlet of the first external cooler and / or the syngas outlet of the stripping unit are connected to the medium inlet of the internal cooler.

[0023] In the propionaldehyde synthesis system described above, the internal cooler includes a first internal cooler and a second internal cooler. The gas phase outlet of the first external cooler is connected to the medium inlet of the first internal cooler, and the synthesis gas outlet of the stripping unit is connected to the medium inlet of the second internal cooler.

[0024] In the propionaldehyde synthesis system described above, the first internal cooler comprises N first internal sub-coolers connected in series, wherein the gas phase outlet of the first external cooler is connected to the medium inlet of the Nth first internal sub-cooler; and / or,

[0025] The second internal cooler includes M second internal sub-coolers connected in series, wherein the synthesis gas outlet of the stripping unit is connected to the medium inlet of the Mth second internal sub-cooler;

[0026] Where N≥1, M≥1.

[0027] In the propionaldehyde synthesis system described above, N=2 and M=2;

[0028] The cooling unit comprises a first first internal sub-cooler, a first second internal sub-cooler, a second first internal sub-cooler, a second second internal sub-cooler, and a first external cooler connected in series.

[0029] This invention provides a method for synthesizing propionaldehyde. By treating the gaseous product with an internal cooling medium, the amount of chilled water used as the first external cooling medium can be reduced, thereby reducing energy consumption and production costs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of a propionaldehyde synthesis system provided by the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Reaction unit; 2-Demister; 4-First internal sub-cooler; 5-First second internal sub-cooler; 6-Second external cooler; 7-Second first internal sub-cooler; 8-Second second internal sub-cooler; 9-First external cooler; 10-Gas-liquid separator; 11-Compressor; 12-Crude propionaldehyde pump; 13-Stripping unit. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] This invention provides a method for synthesizing propionaldehyde, comprising the following steps:

[0036] 1) A feed system including ethylene, carbon monoxide and hydrogen reacts to produce gaseous products including propionaldehyde.

[0037] 2) After the gaseous product is cooled, a crude liquid product of propionaldehyde and the remaining gaseous raw material are obtained. The cooling process includes internal cooling medium treatment and a first external cooling medium treatment in sequence.

[0038] 3) The crude liquid product of propionaldehyde is stripped using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock.

[0039] The remaining gaseous feedstock and / or the stripped syngas feedstock are used as internal cooling media in the internal cooling medium treatment.

[0040] This invention uses ethylene, carbon monoxide, and hydrogen as raw materials to synthesize propionaldehyde through the hydroformylation reaction of ethylene. The gas generated in the reaction is cooled and separated to obtain crude propionaldehyde, which is then stripped to obtain propionaldehyde.

[0041] Specifically, in step 1), a raw material system including ethylene, carbon monoxide, and hydrogen reacts to obtain a gaseous product including propionaldehyde. Using ethylene, carbon monoxide, and hydrogen as raw materials, ethylene undergoes a hydroformylation reaction to synthesize propionaldehyde. The gaseous product including propionaldehyde, in addition to propionaldehyde, also includes unreacted gaseous raw materials such as ethylene, carbon monoxide, and hydrogen.

[0042] In step 2), the gaseous product is cooled to obtain a crude liquid product of propionaldehyde and residual gaseous raw materials. The cooling process includes internal cooling medium treatment and a first external cooling medium treatment. Before cooling the gaseous product obtained from the reaction, it can be demisted, for example, by passing the gaseous product through a demister to remove entrained droplets, such as catalyst liquid. After cooling, the crude liquid product of propionaldehyde and the residual gaseous raw materials can be separated by gas-liquid separation, which can be achieved by a gas-liquid separator. The purpose of cooling the gaseous product obtained above is to separate the crude liquid product of propionaldehyde and the residual gaseous raw materials, such as ethylene, carbon monoxide, and hydrogen. This facilitates the subsequent stripping of the crude liquid product of propionaldehyde and allows the residual gaseous raw materials to be recycled back to the ethylene hydroformylation reaction, thus saving raw materials.

[0043] The cooling process includes internal cooling medium treatment and a first external cooling medium treatment. Since the remaining gaseous raw material is obtained after cooling treatment and has a low temperature, it can be used as the internal cooling medium in the internal cooling medium treatment. The first external cooling medium in the first external cooling medium treatment can be chilled water at a low temperature, which can separate the gaseous product into liquid and obtain the crude liquid product of propionaldehyde and the remaining gaseous raw material. Moreover, performing the internal cooling medium treatment first and then the first external cooling medium treatment can save on the amount of external cooling medium, such as chilled water.

[0044] The present invention does not limit the number of times the internal cooling medium is treated. For example, the internal cooling medium can be treated once or multiple times.

[0045] In step 3), the crude propionaldehyde liquid phase product is stripped using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock. To obtain a purer propionaldehyde liquid, the crude propionaldehyde liquid phase product can be stripped. Before stripping, the separated crude propionaldehyde liquid phase product can be pumped into the stripping unit via a crude propionaldehyde pump to achieve stripping. This invention utilizes syngas feedstock, namely carbon monoxide and hydrogen, to strip the crude propionaldehyde liquid phase product. The syngas feedstock removes gases such as ethylene, carbon monoxide, and hydrogen entrained in the crude propionaldehyde liquid phase product to obtain a purer propionaldehyde. Simultaneously, the stripped syngas feedstock can be used as an internal cooling medium in the internal cooling medium treatment, saving the amount of chilled water used as the first external cooling medium and reducing energy consumption.

[0046] This invention reduces the amount of chilled water used as the first external cooling medium by treating the gaseous products with an internal cooling medium, thereby reducing energy consumption and production costs.

[0047] In some embodiments of the present invention, the heated internal cooling medium obtained after treatment with the internal cooling medium is used as a raw material to participate in the reaction.

[0048] It is understandable that the internal cooling medium, which participates in the internal cooling process—namely, the residual gaseous feedstock and / or the stripped syngas feedstock—will experience a temperature increase while cooling the gaseous products. Since the residual gaseous feedstock and / or the stripped syngas feedstock may include ethylene, carbon monoxide, and hydrogen, they can be used as feedstock in the hydroformylation of ethylene to propionaldehyde. Because the pressure of the residual gaseous feedstock decreases after internal cooling medium treatment, it can be pressurized by a compressor before participating in the hydroformylation of ethylene to propionaldehyde, thus saving raw materials and reducing production costs.

[0049] In some embodiments of the present invention, the internal cooling medium treatment includes a first internal cooling medium treatment and a second internal cooling medium treatment, wherein the remaining gaseous feedstock participates in the first internal cooling medium treatment as the first internal cooling medium, and the stripped syngas feedstock participates in the second internal cooling medium treatment as the second internal cooling medium.

[0050] In this embodiment, the internal cooling medium treatment involving the remaining gaseous feedstock as the internal cooling medium is referred to as the first internal cooling medium treatment; the internal cooling medium treatment involving the stripped syngas feedstock as the internal cooling medium is referred to as the second internal cooling medium treatment.

[0051] In this embodiment, two internal cooling media are used for internal cooling treatment, which can further cool the gaseous products and thus reduce the amount of the first external cooling medium, chilled water.

[0052] In some embodiments of the present invention, the first internal cooling medium treatment includes N first internal cooling medium sub-treatments, wherein the remaining gaseous raw material, as the first internal cooling medium, sequentially participates in the N first internal cooling medium sub-treatments, and the flow direction of the remaining gaseous raw material is opposite to the flow direction of the gaseous product; and / or,

[0053] The second internal cooling medium treatment includes M second internal cooling medium sub-treatments, wherein the stripped syngas feedstock serves as the second internal cooling medium and participates in the M second internal cooling medium sub-treatments in sequence, and the flow direction of the stripped syngas feedstock is opposite to the flow direction of the gas phase products.

[0054] Where N≥1, M≥1.

[0055] In this embodiment, the remaining gaseous feedstock and the stripped syngas feedstock participate in the cooling medium sub-process as the first and second internal cooling media, respectively, with their flow directions opposite to those of the gaseous products. That is, when N=2, the remaining gaseous feedstock first participates in the second first internal cooling medium sub-process, then the first first internal cooling medium sub-process, while the gaseous products first undergo the first first internal cooling medium sub-process, then the second first internal cooling medium sub-process. Similarly, when M=2, the stripped syngas feedstock first participates in the second second internal cooling medium sub-process, then the first second second internal cooling medium sub-process, while the gaseous products first undergo the first second second internal cooling medium sub-process, then the second second second internal cooling medium sub-process.

[0056] In this embodiment, the flow direction of the internal cooling medium is opposite to that of the gaseous products, which can achieve sufficient cooling of the gaseous products and thus reduce the amount of chilled water used as the first external cooling medium.

[0057] In some embodiments of the present invention, N = 2 and M = 2;

[0058] The cooling process includes, in sequence, a first internal cooling medium sub-process, a first second internal cooling medium sub-process, a second first internal cooling medium sub-process, a second second internal cooling medium sub-process, and a first external cooling medium process.

[0059] In this embodiment, N=2 and M=2, that is, the cooling treatment of the gaseous product includes a first internal cooling medium sub-treatment, a first internal cooling medium sub-treatment, a second internal cooling medium sub-treatment, a second internal cooling medium sub-treatment, a second internal cooling medium sub-treatment, and a first external cooling medium treatment in sequence, which can further achieve sufficient cooling of the gaseous product and reduce the amount of chilled water used in the first external cooling medium.

[0060] In some embodiments of the present invention, the cooling process further includes a second external cooling medium process, which is located between a first second internal cooling medium sub-process and a second first internal cooling medium sub-process.

[0061] In this embodiment, the cooling process further includes a second external cooling medium treatment. The second external cooling medium in this treatment can be circulating water. This second external cooling medium treatment is performed between the first second internal cooling medium sub-treatment and the second first internal cooling medium sub-treatment, i.e., before the first external cooling medium treatment. By first using circulating water to treat the gaseous products with the second external cooling medium treatment, and then using chilled water for the first external cooling medium treatment, the amount of the first external cooling medium, such as chilled water, can be reduced.

[0062] In the specific processing, in the first internal cooling medium sub-process, the cooling medium is the residual gaseous raw material, the temperature before cooling is 20-30℃, and the temperature after cooling is 40-50℃; while the temperature of the gaseous product before cooling is 80-110℃, and the temperature after cooling is 72-96℃.

[0063] In the first and second internal cooling medium sub-processing, the cooling medium is the stripped syngas feedstock, with a temperature of 10-35°C before cooling and 60-80°C after cooling; while the temperature of the gaseous products is 72-96°C before cooling and 70-95°C after cooling.

[0064] In the second external cooling medium treatment, the cooling medium is circulating water. The temperature of the gaseous product before cooling treatment is 70-95℃, and the temperature after cooling treatment is 35-45℃.

[0065] In the second internal cooling medium sub-process, the cooling medium is the residual gaseous raw material, with a temperature of -5 to 0°C before cooling and 20 to 30°C after cooling; while the gaseous product has a temperature of 35 to 45°C before cooling and 30 to 40°C after cooling.

[0066] In the second internal cooling medium sub-process, the cooling medium is the stripped syngas feedstock, with a temperature of -25 to -10°C before cooling and 10 to 35°C after cooling; while the temperature of the gaseous products is 30 to 40°C before cooling and 20 to 30°C after cooling.

[0067] In the first external cooling medium treatment, the cooling medium is chilled water, the temperature of the gaseous product before cooling treatment is 20-30℃, and the temperature after cooling treatment is -10-0℃.

[0068] Figure 1 This is a schematic diagram of a propionaldehyde synthesis system provided by the present invention. Figure 1 As shown, the present invention provides a propionaldehyde synthesis system, comprising: a reaction unit 1, a cooling unit and a stripping unit 13;

[0069] The cooling unit includes an internal cooler and a first external cooler in sequence;

[0070] The gas phase outlet of the reaction unit 1 is connected to the material inlet of the internal cooler, the material outlet of the internal cooler is connected to the material inlet of the first external cooler, the liquid phase outlet of the first external cooler is connected to the liquid phase inlet of the stripping unit 13, and the gas phase outlet of the first external cooler and / or the synthesis gas outlet of the stripping unit 13 is connected to the medium inlet of the internal cooler.

[0071] In one embodiment, a feedstock system comprising ethylene, carbon monoxide, and hydrogen undergoes ethylene hydroformylation in reaction unit 1 to obtain a gaseous product including propionaldehyde. The gaseous product is cooled in a cooling unit to obtain a crude liquid product of propionaldehyde and the remaining gaseous feedstock. The crude liquid product of propionaldehyde is stripped in stripping unit 13 using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock.

[0072] Specifically, the gaseous product including propionaldehyde is output from the gas phase outlet of reaction unit 1, enters the internal cooler through the inlet of the internal cooler for cooling, then exits through the outlet of the internal cooler, enters the first external cooler through the inlet of the first external cooler for further cooling, to obtain a crude liquid product of propionaldehyde and the remaining gaseous feedstock. The first external cooling medium in the first external cooler can be chilled water. Optionally, after the gaseous product including propionaldehyde is output from the gas phase outlet of reaction unit 1, it can first pass through a demister 2 to remove droplets before entering the internal cooler for cooling. The crude liquid product of propionaldehyde is output from the liquid phase outlet of the first external cooler, enters the stripping unit 13 through the liquid phase inlet of the stripping unit 13, and is stripped using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock. The remaining gaseous feedstock is output through the gaseous outlet of the first external cooler and enters the internal cooler through the medium inlet of the internal cooler to participate in the internal cooling process as an internal cooling medium. And / or the stripped syngas feedstock is output through the syngas outlet of the stripping unit 13 and enters the internal cooler through the medium inlet of the internal cooler to participate in the internal cooling process as an internal cooling medium.

[0073] The present invention does not limit the number of internal coolers; there may be one or more.

[0074] The present invention does not limit the type of reaction unit 1, for example, it can be a reaction vessel; the present invention does not limit the type of stripping unit 13, for example, it can be a stripping tower.

[0075] In this embodiment, the gaseous products are cooled by an internal cooler before undergoing the first external cooling treatment, which reduces the amount of chilled water used as the first external cooling medium, thereby reducing energy consumption and production costs.

[0076] The reaction unit 1 in this invention also includes a raw material inlet, and the medium outlet of the internal cooler is connected to the raw material inlet.

[0077] Specifically, the remaining gaseous feedstock and / or stripped syngas feedstock are output through the medium outlet of the internal cooler and then enter the reaction unit 1 through the feedstock inlet to participate in the hydroformation of ethylene to propionaldehyde. Since the remaining gaseous feedstock is obtained after cooling treatment in the cooling unit, its pressure is reduced. It can be pressurized in the compressor 11 before participating in the hydroformation of ethylene to propionaldehyde. At this time, the medium outlet of the internal cooler is connected to the feedstock inlet through the compressor 11.

[0078] In some embodiments of the present invention, the internal cooler includes a first internal cooler and a second internal cooler, the gas phase outlet of the first external cooler is connected to the medium inlet of the first internal cooler, and the syngas outlet of the stripping unit is connected to the medium inlet of the second internal cooler.

[0079] In this embodiment, the internal cooler includes a first internal cooler and a second internal cooler. Specifically, the remaining gaseous feedstock is output through the gaseous outlet of the first external cooler and enters the first internal cooler through the medium inlet to serve as the first internal cooling medium for cooling the gaseous products. The stripped syngas feedstock enters the second internal cooler through the medium inlet to serve as the second internal cooling medium for cooling the gaseous products.

[0080] In this embodiment, the gaseous product undergoes two internal cooling processes via a first internal cooler and a second internal cooler, which further cools the gaseous product and reduces the amount of chilled water used as the first external cooling medium.

[0081] In some embodiments of the present invention, the first internal cooler includes N first internal sub-coolers connected in series, wherein the gas phase outlet of the first external cooler is connected to the medium inlet of the Nth first internal sub-cooler; and / or,

[0082] The second internal cooler includes M second internal sub-coolers connected in series, wherein the synthesis gas outlet of the stripping unit is connected to the medium inlet of the Mth second internal sub-cooler;

[0083] Where N≥1, M≥1.

[0084] In this embodiment, the first internal cooler includes N first internal sub-coolers connected in series. The remaining gaseous raw material is output from the gaseous outlet of the first external cooler, enters the Nth first internal sub-cooler through the medium inlet of the Nth first internal sub-cooler to cool the gaseous product; then it is output from the medium outlet of the Nth first internal sub-cooler, enters the N-1th first internal sub-cooler through the medium inlet of the (N-1)th first internal sub-cooler to cool the gaseous product; and so on. The remaining gaseous raw material enters the second first internal sub-cooler through the medium inlet of the second first internal sub-cooler to cool the gaseous product; then it is output from the medium outlet of the second first internal sub-cooler, enters the first first internal sub-cooler through the medium inlet of the first first internal sub-cooler to cool the gaseous product. The gaseous products enter the first internal sub-cooler through the inlet of the first internal sub-cooler for cooling, exit through the outlet of the first internal sub-cooler, and enter the second internal sub-cooler through the inlet of the second internal sub-cooler for cooling; and so on, the gaseous products enter the (N-1)th internal sub-cooler through the inlet of the N-1th internal sub-cooler for cooling, exit through the outlet of the N-1th internal sub-cooler, and enter the Nth internal sub-cooler through the inlet of the Nth internal sub-cooler for cooling.

[0085] The second internal cooler comprises M second internal sub-coolers connected in series. After stripping, the syngas feedstock is output from the syngas outlet of the stripping unit and enters the Mth second internal sub-cooler through the medium inlet to cool the gaseous products. Then, it is output from the medium outlet of the Mth second internal sub-cooler and enters the (M-1)th second internal sub-cooler through the medium inlet to cool the gaseous products. This process continues, with the syngas feedstock after stripping entering the second second internal sub-cooler through the medium inlet to cool the gaseous products. Then, it is output from the medium outlet of the second second internal sub-cooler and enters the first second internal sub-cooler through the medium inlet to cool the gaseous products. The gaseous products enter the first second internal sub-cooler through the inlet of the first second internal sub-cooler for cooling, exit through the outlet of the first second internal sub-cooler, and enter the second second internal sub-cooler through the inlet of the second second internal sub-cooler for cooling; and so on, the gaseous products enter the (M-1)th second internal sub-cooler through the inlet of the M-1th second internal sub-cooler for cooling, exit through the outlet of the M-1th second internal sub-cooler, and enter the Mth second internal sub-cooler through the inlet of the Mth second internal sub-cooler for cooling.

[0086] In this embodiment, the first internal cooler and the second internal cooler each include N first internal sub-coolers connected in series and M second internal sub-coolers connected in series. The flow direction of the remaining gaseous raw material and the stripped syngas raw material is opposite to the flow direction of the gaseous product, which can achieve sufficient cooling of the gaseous product and reduce the amount of chilled water used as the first external cooling medium.

[0087] In some embodiments of the present invention, N = 2 and M = 2;

[0088] The cooling unit includes a first internal sub-cooler 4, a first internal sub-cooler 5, a second internal sub-cooler 7, a second internal sub-cooler 8, and a first external cooler 9 connected in series.

[0089] In this embodiment, N=2 and M=2, that is, the cooling unit includes a first first internal sub-cooler 4, a first second internal sub-cooler 5, a second first internal sub-cooler 7, a second second internal sub-cooler 8 and a first external cooler 9 connected in series.

[0090] Specifically, the gaseous product enters the first internal sub-cooler 4 through its inlet for cooling and exits through its outlet. It then enters the second internal sub-cooler 5 through its inlet for cooling and exits through its outlet. Next, it enters the second internal sub-cooler 7 through its inlet for cooling and exits through its outlet. Finally, it enters the second internal sub-cooler 8 through its inlet for cooling and exits through its outlet. Finally, it enters the first external cooler 9 through its inlet for cooling. The product cooled by the first external cooler 9 then enters the gas-liquid separator 10 for gas-liquid separation, yielding a crude liquid product of propionaldehyde and the remaining gaseous feedstock. The crude liquid product is then pumped by the crude propionaldehyde pump 12 into the stripping unit 13 for stripping to obtain propionaldehyde and stripped syngas feedstock.

[0091] In this embodiment, N=2 and M=2 are specified, which can further achieve sufficient cooling of the gaseous products and reduce the amount of the first external cooling medium, chilled water.

[0092] The cooling unit in this invention further includes a second external cooler 6, and the first second internal sub-cooler 5 is connected to the second first internal sub-cooler 7 through the second external cooler 6.

[0093] The cooling unit in this invention also includes a second external cooler 6. The gaseous product output from the outlet of the first second internal sub-cooler 5 enters the second external cooler 6 through the inlet for cooling, then exits through the outlet of the second external cooler 6 and enters the second first internal sub-cooler 7 through the inlet for further cooling. That is, cooling is performed in the second external cooler 6 before cooling in the first external cooler 9, which reduces the amount of the first external cooling medium, such as chilled water, required.

[0094] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0095] Example 1

[0096] The system in this embodiment is a propionaldehyde synthesis system, such as... Figure 1As shown, it includes a reaction unit 1 (reactor); a demister 2; a first internal sub-cooler 4; a first second internal sub-cooler 5; a second external cooler 6; a second first internal sub-cooler 7; a second second internal sub-cooler 8; a first external cooler 9; a gas-liquid separator 10; a compressor 11; a crude propionaldehyde pump 12; and a stripping unit 13 (stripping tower).

[0097] In this configuration, the gas phase outlet of reaction unit 1 is connected to the gas phase inlet of demister 2; the gas phase outlet of demister 2 is connected to the material inlet of the first internal sub-cooler 4; the material outlet of the first internal sub-cooler 4 is connected to the material inlet of the first second internal sub-cooler 5; the material outlet of the first second internal sub-cooler 5 is connected to the material inlet of the second external cooler 6; the material outlet of the second external cooler 6 is connected to the material inlet of the second internal sub-cooler 7; the material outlet of the second internal sub-cooler 7 is connected to the material inlet of the second internal sub-cooler 8; the material outlet of the second internal sub-cooler 8 is connected to the material inlet of the first external cooler 9; the material outlet of the first external cooler 9 is connected to the material inlet of gas-liquid separator 10; and the gas-liquid separator 10... The gas phase outlet is connected to the medium inlet of the second first internal sub-cooler 7; the liquid phase outlet of the gas-liquid separator 10 is connected to the liquid phase inlet of the crude propionaldehyde pump 12; the liquid phase outlet of the crude propionaldehyde pump 12 is connected to the liquid phase inlet of the stripping unit 13; the synthesis gas outlet of the stripping unit 13 is connected to the medium inlet of the second second internal sub-cooler 8; the medium outlet of the second second internal sub-cooler 8 is connected to the medium inlet of the first second internal sub-cooler 5; the medium outlet of the first second internal sub-cooler 5 is connected to the raw material inlet of the reaction unit 1; the medium outlet of the second first internal sub-cooler 7 is connected to the medium inlet of the first first internal sub-cooler 4; the medium outlet of the first first internal sub-cooler 4 is connected to the gas phase inlet of the compressor 11; and the gas phase outlet of the compressor 11 is connected to the raw material inlet of the reaction unit 1.

[0098] Specifically, the feedstock system (stream a), comprising ethylene, carbon monoxide, and hydrogen, undergoes hydroformylation in reaction unit 1 to obtain a gaseous product (stream b) containing propionaldehyde. After demisting by demister 2, the liquid product (stream c) returns to reaction unit 1. The gaseous product (stream f) enters the first internal sub-cooler 4 for cooling to obtain stream g, with the remaining gaseous feedstock (stream n) as the cooling medium. After cooling, stream o is obtained and pressurized by compressor 11 to obtain stream p. Stream p returns to stream a to continue participating in the ethylene hydroformylation reaction. The temperature of stream f is 80–110°C, stream g is 72–96°C, stream n is 20–30°C, and stream o is 40–50°C.

[0099] After entering the first second internal sub-cooler 5 for cooling, the g stream is obtained as the h stream, with the stripped syngas feedstock q stream as the cooling medium. After cooling, the h stream is obtained as the r stream, and the p stream is returned to the a stream to continue participating in the ethylene hydroformylation reaction. The temperature of the h stream is 70–95℃, the temperature of the q stream is 10–35℃, and the temperature of the r stream is 60–80℃.

[0100] After the h-stream enters the second external cooler 6 for cooling, it becomes the i-stream. The second external cooling medium is circulating water. The temperature of the i-stream is 35-45℃.

[0101] After entering the second internal sub-cooler 7 for cooling, the i-th stream is obtained as the j-th stream. The cooling medium is the residual gaseous raw material m-th stream, which is then cooled to obtain the n-th stream. The temperature of the j-th stream is 30-40℃, and the temperature of the m-th stream is -5-0℃.

[0102] After entering the second internal sub-cooler 8 for cooling, stream j becomes stream k. The cooling medium is stripped syngas feedstock stream t, which, after cooling, becomes stream q. Stream k has a temperature of 20–30°C, and stream t has a temperature of -25–-10°C.

[0103] The k-stream enters the first external cooler 9 for cooling to obtain the l-stream. The first external cooling medium is chilled water. The temperature of the l-stream is -10 to 0℃.

[0104] The l-stream enters the gas-liquid separator 10 for gas-liquid separation to obtain a crude liquid product of propionaldehyde and a residual gaseous raw material. The residual gaseous raw material m-stream enters the second first internal sub-cooler 7 for internal cooling treatment. The crude liquid product s-stream of propionaldehyde is processed by the crude propionaldehyde pump 12 and becomes a v-stream, which enters the stripping unit 13 for stripping treatment to obtain a crude propionaldehyde w-stream, which enters the next process. The syngas raw material u-stream enters the stripping unit 13 to strip the v-stream and obtain a t-stream, which enters the second second internal sub-cooler 8 for internal cooling treatment.

[0105] Comparative Example 1

[0106] The propionaldehyde synthesis system of Comparative Example 1 is basically the same as that of Example 1, except that it does not include the first first internal sub-cooler 4, the first second internal sub-cooler 5, the second first internal sub-cooler 7, and the second second internal sub-cooler 8. That is, the gaseous products are not cooled by internal cooling media, and only circulating water and chilled water are used to cool the gaseous products. The temperature after cooling is -10 to 0°C.

[0107] Compared with Comparative Example 1, Example 1 reduces the consumption of circulating water and chilled water by 30% respectively when cooling the same mass of material to the same temperature, thus reducing energy consumption.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing propionaldehyde, characterized in that, Includes the following steps: 1) A feed system including ethylene, carbon monoxide and hydrogen reacts to produce gaseous products including propionaldehyde. 2) After the gaseous product is cooled, a crude liquid product of propionaldehyde and the remaining gaseous raw material are obtained. The cooling process includes internal cooling medium treatment and a first external cooling medium treatment in sequence. 3) The crude liquid product of propionaldehyde is stripped using syngas feedstock to obtain propionaldehyde and stripped syngas feedstock; The remaining gaseous feedstock and / or the stripped syngas feedstock serve as internal cooling media in the internal cooling medium treatment. The internal cooling medium treatment includes a first internal cooling medium treatment and a second internal cooling medium treatment. The first internal cooling medium treatment includes N first internal cooling medium sub-treatments, wherein the remaining gaseous raw material, as the first internal cooling medium, sequentially participates in the N first internal cooling medium sub-treatments, and the flow direction of the remaining gaseous raw material is opposite to the flow direction of the gaseous product; and / or, The second internal cooling medium treatment includes M second internal cooling medium sub-treatments, wherein the stripped syngas feedstock serves as the second internal cooling medium and participates in the M second internal cooling medium sub-treatments in sequence, and the flow direction of the stripped syngas feedstock is opposite to the flow direction of the gas phase products. Where N=2 and M=2, the cooling process sequentially includes a first internal cooling medium sub-process, a first internal cooling medium sub-process, a second internal cooling medium sub-process, a second internal cooling medium sub-process, a second internal cooling medium sub-process, and a first external cooling medium process.

2. The method according to claim 1, characterized in that, The heated internal cooling medium, obtained after treatment with the internal cooling medium, is used as a raw material in the reaction.

3. The method according to claim 1 or 2, characterized in that, The cooling process further includes a second external cooling medium treatment, which is located between a first second internal cooling medium sub-treatment and a second first internal cooling medium sub-treatment.

4. A system for implementing the propionaldehyde synthesis method according to any one of claims 1-3, characterized in that, include: The unit consists of a reaction unit, a cooling unit, and a stripping unit. The cooling unit includes an internal cooler and a first external cooler in sequence; The gas phase outlet of the reaction unit is connected to the material inlet of the internal cooler, the material outlet of the internal cooler is connected to the material inlet of the first external cooler, the liquid phase outlet of the first external cooler is connected to the liquid phase inlet of the stripping unit, and the gas phase outlet of the first external cooler and / or the syngas outlet of the stripping unit is connected to the medium inlet of the internal cooler. The internal cooler includes a first internal cooler and a second internal cooler; The first internal cooler comprises N first internal sub-coolers connected in series, wherein the gas phase outlet of the first external cooler is connected to the medium inlet of the Nth first internal sub-cooler; and / or, The second internal cooler includes M second internal sub-coolers connected in series, wherein the synthesis gas outlet of the stripping unit is connected to the medium inlet of the Mth second internal sub-cooler; N=2 and M=2, the cooling unit includes a first first internal sub-cooler, a first second internal sub-cooler, a second first internal sub-cooler, a second second internal sub-cooler and a first external cooler connected in series.

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