Hydroxyacetonitrile continuous reactor

Abstract

The invention relates to the technical field of chemical equipment, in particular to a hydroxyacetonitrile continuous reactor which comprises a first-stage falling film reactor, a second-stage mixing reactor, a first-stage circulating pipeline and a second-stage circulating pipeline, after hydrocyanic acid mixed gas enters the first-stage falling film reactor, formaldehyde and first-stage circulating liquid enter the first-stage falling film reactor from the two sides of the top of the first-stage falling film reactor respectively, and then formaldehyde and second-stage circulating liquid enter the second-stage falling film reactor; uniform falling films are formed on the inner walls of a plurality of reaction flow guide pipes and react, and cooling water outside the pipes circulates to timely remove reaction heat; after the primary reaction, returning one part of the material to the top through a primary circulation pipeline for continuous reaction, and enabling the other part to enter a secondary mixing reactor; and in the second-stage mixing reactor, the residual hydrocyanic acid is further mixed and reacted with glycolonitrile returned by a second-stage circulating pipeline, part of the final product is extracted, and part of the final product is circulated back to a second-stage circulating material inlet. The system strengthens heat and mass transfer through a falling film structure, and ensures full reaction of raw materials through two-stage circulation, and the product quality is stable.

Description

Technical Field

[0001] This invention relates to the field of chemical equipment technology, and in particular to a hydroxyacetonitrile continuous reactor. Background Technology

[0002] Hydroxyacetonitrile, also known as ethanol nitrile, is a key chemical intermediate mainly used in the synthesis of important amino acids such as glycine and iminodiacetic acid, as well as complexing agents. It has wide applications in pesticides, pharmaceuticals, electroplating and other fields.

[0003] Currently, the industrial production of hydroxyacetonitrile mainly employs a condensation reaction between hydrogen cyanide (HCN) and formaldehyde (HCHO). However, traditional production methods often utilize batch reactors. This approach has several inherent drawbacks: Reaction efficiency and capacity limitations: Intermittent operation requires frequent steps such as feeding, reaction, cooling, discharging and cleaning, resulting in long non-productive times, low equipment utilization and overall capacity, making it difficult to meet the needs of large-scale continuous production.

[0004] Difficulty in removing heat of reaction leads to unstable product quality: The condensation reaction of HCN and HCHO is a strongly exothermic reaction. In a batch reactor, the heat of reaction is released in a concentrated manner, and if it cannot be removed in a timely and efficient manner, it can easily lead to local overheating. This not only causes the decomposition of heat-sensitive substances such as hydroxyacetonitrile and increases side reactions (such as polymerization to form tar-like substances), resulting in a decrease in product yield and purity, but also leads to unstable product quality between different batches due to large fluctuations in reaction temperature.

[0005] In summary, traditional reactors for hydroxyacetonitrile production suffer from low equipment utilization and overall capacity, making it difficult to meet the demands of large-scale continuous production. Furthermore, they present challenges in removing reaction heat, leading to unstable product quality. Summary of the Invention

[0006] The purpose of this invention is to provide a continuous reactor for hydroxyacetonitrile production, which solves the problems of low equipment utilization and overall capacity of traditional reactors for hydroxyacetonitrile production, making it difficult to meet the needs of large-scale continuous production, and the difficulty in removing reaction heat, resulting in unstable product quality.

[0007] To achieve the above objectives, the present invention provides a hydroxyacetonitrile continuous reactor, comprising a primary falling film reactor, a secondary mixing reactor, a primary circulation pipeline, and a secondary circulation pipeline. The middle section of the primary falling film reactor is a falling film reaction zone, and multiple reaction guide pipes are arranged inside the falling film reaction zone. The primary falling film reactor is also provided with a cooling water inlet and a cooling water outlet, which are located on opposite sides of the falling film reaction zone. A mixed gas inlet is provided at the top of the primary falling film reactor. A formaldehyde inlet and a primary circulating material inlet are respectively provided on opposite sides of the top of the primary falling film reactor, located on opposite sides above the falling film reaction zone. A primary circulating material outlet is provided on the side of the bottom of the primary falling film reactor. The input end of the primary circulation pipeline is connected to the primary circulating material outlet, and the output end of the primary circulation pipeline is connected to the primary circulating material inlet. The bottom of the primary falling film reactor is connected to the secondary mixing reactor. The top side of the secondary mixing reactor is provided with a secondary circulating material inlet, the bottom of the secondary mixing reactor is provided with a product outlet, and the bottom side of the secondary mixing reactor is provided with a secondary circulating material outlet. The input end of the secondary circulation pipeline is connected to the secondary circulating material outlet, and the output end of the secondary circulation pipeline is connected to the secondary circulating material inlet.

[0008] The primary circulation pipeline includes a primary circulation pump, a first connecting pipe, and a second connecting pipe. The first connecting pipe is provided at the input end of the primary circulation pump, and the second connecting pipe is provided at the output end of the primary circulation pump. The first connecting pipe is connected to the primary circulation material outlet, and the second connecting pipe is connected to the primary circulation material inlet.

[0009] The second circulation pipeline includes a secondary circulation pump, a third connecting pipe, and a fourth connecting pipe. The third connecting pipe is provided at the input end of the secondary circulation pump, and the fourth connecting pipe is provided at the output end of the secondary circulation pump. The third connecting pipe is connected to the secondary circulation material outlet, and the fourth connecting pipe is connected to the secondary circulation material inlet.

[0010] The secondary mixing reactor is provided with a feed cylinder at its top, which extends into the interior of the primary falling film reactor. The diameter of the feed cylinder is smaller than that of the primary falling film reactor.

[0011] The top opening of the feed cylinder is located above the primary circulating material outlet, and the secondary circulating material inlet is located on the side of the feed cylinder and outside the primary falling film reactor.

[0012] The secondary mixing reactor is equipped with packing material inside.

[0013] The top of the primary falling film reactor is equipped with a gas distribution plate.

[0014] This invention discloses a continuous hydroxyacetonitrile reactor, comprising a primary falling film reactor, a secondary mixing reactor, a primary circulation pipeline, and a secondary circulation pipeline. Hydrogen cyanide mixed gas enters the primary falling film reactor from the top, while formaldehyde and primary circulating liquid enter from the top sides respectively. A uniform falling film forms on the inner walls of multiple reaction guide pipes, and a reaction occurs. Cooling water circulates outside the pipes to promptly remove the heat of reaction. After the initial reaction, a portion of the material returns to the top via the primary circulation pipeline to continue the reaction, while the other portion enters the secondary mixing reactor. In the secondary mixing reactor, residual hydrogen cyanide further mixes and reacts with the hydroxyacetonitrile returning via the secondary circulation pipeline. The final product is partially collected and partially recycled back to the secondary circulating material inlet. This system enhances heat and mass transfer through the falling film structure, achieving reaction temperature control and increased production capacity. The two-stage circulation ensures sufficient reaction of raw materials and stable product quality, meeting the requirements for large-scale continuous, safe, and efficient production. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the hydroxyacetonitrile continuous reactor provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the internal structure of the hydroxyacetonitrile continuous reactor provided by the present invention.

[0018] 101-First-stage falling film reactor, 102-Second-stage mixing reactor, 103-Falling film reaction zone, 104-Reaction guide pipe, 105-Cooling water inlet, 106-Cooling water outlet, 107-Mixed gas inlet, 108-Formaldehyde inlet, 109-First-stage circulating material inlet, 110-First-stage circulating material outlet, 111-Second-stage circulating material inlet, 112-Product outlet, 113-Second-stage circulating material outlet, 114-First-stage circulating pump, 115-First connecting pipe, 116-Second connecting pipe, 117-Second-stage circulating pump, 118-Third connecting pipe, 119-Fourth connecting pipe, 120-Feed cylinder, 121-Packing, 122-Gas distribution plate. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] Please see Figure 1 and Figure 2 This invention provides a continuous hydroxyacetonitrile reactor, comprising a primary falling film reactor 101, a secondary mixing reactor 102, a primary circulation pipeline, and a secondary circulation pipeline. The middle section of the primary falling film reactor 101 is a falling film reaction zone 103, which is internally equipped with multiple reaction guide pipes 104. The primary falling film reactor 101 also has a cooling water inlet 105 and a cooling water outlet 106, located on opposite sides of the falling film reaction zone 103. The reactor 101 is provided with a mixed gas inlet 107 at the top. The top of the primary falling film reactor 101 is provided with a formaldehyde inlet 108 and a primary circulating material inlet 109 on both sides. The formaldehyde inlet 108 and the primary circulating material inlet 109 are respectively located on both sides above the falling film reaction zone 103. The bottom of the primary falling film reactor 101 is provided with a primary circulating material outlet 110. The input end of the primary circulating pipeline is connected to the primary circulating material outlet 110, and the output end of the primary circulating pipeline is connected to the primary circulating material inlet 109. The bottom of the primary falling film reactor 101 is connected to the secondary mixing reactor 102. The top side of the secondary mixing reactor 102 is provided with a secondary circulating material inlet 111, the bottom of the secondary mixing reactor 102 is provided with a product outlet 112, and the bottom side of the secondary mixing reactor 102 is provided with a secondary circulating material outlet 113. The input end of the secondary circulation pipeline is connected to the secondary circulating material outlet 113, and the output end of the secondary circulation pipeline is connected to the secondary circulating material inlet 111.

[0021] In this embodiment, the hydrogen cyanide mixed gas enters the primary falling film reactor 101 from the top, while formaldehyde and the primary circulating liquid enter from the top sides respectively. A uniform falling film forms on the inner walls of the multiple reaction guide pipes 104, and a reaction occurs. Cooling water circulating outside the pipes promptly removes the heat of reaction. After the initial reaction, part of the material returns to the top via the primary circulating pipeline to continue the reaction, while the other part enters the secondary mixing reactor 102. In the secondary mixing reactor 102, the residual hydrogen cyanide further mixes and reacts with the hydroxyacetonitrile returning via the secondary circulating pipeline. The final product is partially collected and partially recycled back to the secondary circulating material inlet 111. This system enhances heat and mass transfer through the falling film structure, achieving reaction temperature control and increased production capacity. The two-stage circulation ensures sufficient reaction of raw materials and stable product quality, meeting the requirements for large-scale continuous, safe, and efficient production.

[0022] Furthermore, the primary circulation pipeline includes a primary circulation pump 114, a first connecting pipe 115, and a second connecting pipe 116. The input end of the primary circulation pump 114 is provided with the first connecting pipe 115, and the output end of the primary circulation pump 114 is provided with the second connecting pipe 116. The first connecting pipe 115 is connected to the primary circulation material outlet 110, and the second connecting pipe 116 is connected to the primary circulation material inlet 109.

[0023] Furthermore, the second circulation pipeline includes a secondary circulation pump 117, a third connecting pipe 118, and a fourth connecting pipe 119. The input end of the secondary circulation pump 117 is provided with the third connecting pipe 118, and the output end of the secondary circulation pump 117 is provided with the fourth connecting pipe 119. The third connecting pipe 118 is connected to the secondary circulation material outlet 113, and the fourth connecting pipe 119 is connected to the secondary circulation material inlet 111.

[0024] Furthermore, a feed cylinder 120 is provided at the top of the secondary mixing reactor 102, and the feed cylinder 120 extends into the interior of the primary falling film reactor 101. The diameter of the feed cylinder 120 is smaller than the diameter of the primary falling film reactor 101.

[0025] In this embodiment, by incorporating a small-diameter feed cylinder 120 inside the primary falling film reactor 101, which serves as the feed channel for the secondary mixing reactor 102, seamless connection and smooth material transition between the two reactors are achieved. This structural design effectively reduces material retention and backmixing during the transfer process, ensuring the continuity and stability of the reaction process. Simultaneously, this internal feed structure optimizes the equipment's spatial layout, making the system structure more compact and further enhancing the overall integrity and efficiency of continuous production.

[0026] Furthermore, the top opening of the feed cylinder 120 is located above the primary circulating material outlet 110, and the secondary circulating material inlet 111 is located on the side of the feed cylinder 120 and outside the primary falling film reactor 101.

[0027] Furthermore, the interior of the secondary mixing reactor 102 is provided with packing material 121.

[0028] In this embodiment, by providing the packing 121 inside the secondary mixing reactor 102, the contact area between the gas and liquid phases is significantly increased, providing an efficient mass transfer and reaction interface for residual hydrogen cyanide and recycled hydroxyacetonitrile.

[0029] Furthermore, a gas distribution plate 122 is provided at the top of the primary falling film reactor 101.

[0030] In this embodiment, by setting the gas distribution plate 122 at the top of the primary falling film reactor 101, the hydrogen cyanide mixed gas is evenly distributed and enters the multiple reaction guide pipes 104, ensuring the uniformity and stability of the contact between the gas and the falling film on the inner wall of the pipe.

[0031] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A continuous hydroxyacetonitrile reactor, characterized in that, The reactor comprises a primary falling film reactor, a secondary mixing reactor, a primary circulation pipeline, and a secondary circulation pipeline. The middle section of the primary falling film reactor is a falling film reaction zone, which contains multiple reaction guide pipes. The primary falling film reactor also has a cooling water inlet and a cooling water outlet, located on opposite sides of the falling film reaction zone. A mixed gas inlet is located at the top of the primary falling film reactor. Formaldehyde inlets and primary circulating material inlets are located on opposite sides of the top of the primary falling film reactor, respectively, above the falling film reaction zone. A primary circulating material outlet is located on the side of the bottom of the primary falling film reactor. The input end of the primary circulation pipeline is connected to the primary circulating material outlet, and the output end of the primary circulation pipeline is connected to the primary circulating material inlet. The bottom of the primary falling film reactor is connected to the secondary mixing reactor. The top side of the secondary mixing reactor is provided with a secondary circulating material inlet, the bottom of the secondary mixing reactor is provided with a product outlet, and the bottom side of the secondary mixing reactor is provided with a secondary circulating material outlet. The input end of the secondary circulation pipeline is connected to the secondary circulating material outlet, and the output end of the secondary circulation pipeline is connected to the secondary circulating material inlet.

2. The hydroxyacetonitrile continuous reactor as described in claim 1, characterized in that, The primary circulation pipeline includes a primary circulation pump, a first connecting pipe, and a second connecting pipe. The first connecting pipe is provided at the input end of the primary circulation pump, and the second connecting pipe is provided at the output end of the primary circulation pump. The first connecting pipe is connected to the primary circulation material outlet, and the second connecting pipe is connected to the primary circulation material inlet.

3. The hydroxyacetonitrile continuous reactor as described in claim 2, characterized in that, The second circulation pipeline includes a secondary circulation pump, a third connecting pipe, and a fourth connecting pipe. The third connecting pipe is provided at the input end of the secondary circulation pump, and the fourth connecting pipe is provided at the output end of the secondary circulation pump. The third connecting pipe is connected to the secondary circulation material outlet, and the fourth connecting pipe is connected to the secondary circulation material inlet.

4. The hydroxyacetonitrile continuous reactor as described in claim 3, characterized in that, The secondary mixing reactor is provided with a feed cylinder at the top, which extends into the interior of the primary falling film reactor. The diameter of the feed cylinder is smaller than the diameter of the primary falling film reactor.

5. The hydroxyacetonitrile continuous reactor as described in claim 4, characterized in that, The top opening of the feed cylinder is located above the primary circulating material outlet, and the secondary circulating material inlet is located on the side of the feed cylinder and outside the primary falling film reactor.

6. The hydroxyacetonitrile continuous reactor as described in claim 5, characterized in that, The interior of the secondary mixing reactor is filled with packing material.

7. The hydroxyacetonitrile continuous reactor as described in claim 6, characterized in that, A gas distribution plate is installed at the top of the primary falling film reactor.

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