Food-grade ammonia water production system and method

Abstract

This invention relates to the field of chemical technology, and particularly to a food-grade ammonia production system and method. The food-grade ammonia production system includes a liquid ammonia tank, a first heat exchanger, a first buffer device, an absorption tower, and a second heat exchanger connected in sequence. The first heat exchanger heats the liquid ammonia to form ammonia gas; the second heat exchanger cools the ammonia water. An ammonia gas pipeline is provided between the first buffer device and the absorption tower, and a pressure sensor is installed on the ammonia gas pipeline. A second buffer device is provided between the pressure sensor and the ammonia gas pipeline. The first buffer device includes an inlet pipe, multiple parallel distribution pipes, and an exhaust pipe connected in sequence; the diameter of the distribution pipes is smaller than that of the inlet pipe or the exhaust pipe. The food-grade ammonia production system of this invention can reduce the pipeline pressure fluctuation caused by the process of liquid ammonia forming ammonia gas, improve production stability, and make the detected pipeline pressure values ​​more valuable for reference.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a food-grade ammonia production system and method. Background Technology

[0002] In the industrial production of ammonia water, continuous monitoring of the ammonia pressure in the pipeline is necessary to control the input of water and ammonia to the absorption tower and ensure efficient reaction. In the process of producing ammonia water using ammonia gas, liquid ammonia must first be heated to form ammonia gas. During this process, incomplete vaporization of liquid ammonia may occur locally: unvaporized liquid ammonia flowing in the pipeline may suddenly and violently vaporize due to pressure drops (such as flowing through valves or bends) or local temperature increases (such as ambient temperature fluctuations), causing instantaneous volume expansion and a sudden increase in pipeline pressure. This sudden increase in pipeline pressure occurs continuously and frequently during production, causing the values ​​of the pipeline pressure sensors to fluctuate within a wide range, making it impossible to obtain effective readings and thus hindering precise control of the water in the absorption tower.

[0003] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a food-grade ammonia water production system and method, which aims to solve the technical problem that excessive pressure fluctuations in pipelines cause pressure sensors to fail to read accurately.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides a food-grade ammonia water production system, comprising a liquid ammonia tank, a first heat exchanger, a first buffer device, an absorption tower, and a second heat exchanger connected in sequence; the first heat exchanger is used to heat liquid ammonia to form ammonia gas; the second heat exchanger is used to cool the ammonia water; an ammonia gas pipeline is provided between the first buffer device and the absorption tower, and a pressure sensor is provided on the ammonia gas pipeline; a second buffer device is provided between the pressure sensor and the ammonia gas pipeline; the first buffer device includes an inlet pipe, multiple parallel distribution pipes, and an exhaust pipe connected in sequence; the diameter of the distribution pipes is smaller than that of the inlet pipe or the exhaust pipe.

[0007] The food-grade ammonia production system, wherein the first buffer device is equipped with an insulated shell.

[0008] In the food-grade ammonia water production system, the second buffer device is provided with a buffer chamber, and a first gas distribution plate is provided in the middle of the buffer chamber. The first gas distribution plate is uniformly provided with multiple through holes.

[0009] The food-grade ammonia water production system includes an ammonia release plate at the lower part of the absorption tower, with multiple release holes evenly distributed on the plate; the ammonia release plate is connected to a first buffer device; multiple spray devices are installed at the upper part of the absorption tower, arranged sequentially from top to bottom; the spray devices are connected to process water pipelines; and the bottom of the absorption tower is connected to a second heat exchanger.

[0010] The food-grade ammonia production system further includes a second gas distribution plate between two adjacent spray devices.

[0011] The food-grade ammonia production system comprises: a first heat exchanger including a first heat exchange pipe and a second heat exchange pipe; a second heat exchanger including a third heat exchange pipe and a fourth heat exchange pipe; the two ends of the first heat exchange pipe being connected to a liquid ammonia tank and a first buffer device, respectively; the inlet end of the third heat exchange pipe being connected to the bottom of an absorption tower, and its outlet end being connected to an ammonia storage tank; the inlet end of the second heat exchange pipe being connected to the outlet end of the fourth heat exchange pipe, and its outlet end being connected to a process water recovery device; and the inlet end of the fourth heat exchange pipe being connected to a cooling water pipe.

[0012] The food-grade ammonia production system further includes a heating device between the second heat exchange pipe and the fourth heat exchange pipe.

[0013] In the aforementioned food-grade ammonia production system, a packing layer is provided above each second gas distribution disc.

[0014] In the aforementioned food-grade ammonia water production system, a plurality of conical gas outlets are uniformly arranged on the top surface of the second gas distribution disk; a plurality of liquid collection tanks are arranged on the top surface of the second gas distribution disk, and the plurality of conical gas outlets are distributed in the plurality of liquid collection tanks, wherein the liquid collection tanks extend downward at an incline from the center to the edge of the second gas distribution disk; a flange extending downward at an incline from the center to the edge is correspondingly formed at the bottom of the liquid collection tank; the flange is located at the bottom of the second gas distribution disk.

[0015] A second aspect of the present invention provides a method for preparing food-grade ammonia water, wherein food-grade ammonia water is prepared using the food-grade ammonia water production system described above.

[0016] Beneficial Effects: This invention provides a food-grade ammonia production system. The system connects a first buffer device to the outlet of a first heat exchanger, buffering the pressure surge primarily caused by the heat exchanger. Multiple parallel distribution pipes distribute the pressure and block some of the high-pressure gas, while simultaneously extending the gas path. During this process, the instantaneous high pressure of the ammonia decreases to some extent, and it continues to flow downstream at a relatively low pressure, thus reducing fluctuations in the pressure sensor readings. Furthermore, this invention also includes a second buffer device between the pressure sensor and the ammonia pipeline, further stabilizing the pressure at the detection end and minimizing fluctuations in the pressure sensor readings, making the pressure readings more reliable. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a food-grade ammonia production system.

[0018] Figure 2 This is a schematic diagram of the first buffer device.

[0019] Figure 3 This is a schematic diagram of the second buffer device.

[0020] Figure 4 This is a top view of the second gas distribution disk.

[0021] Figure 5 for Figure 4 A sectional view along line A-A'.

[0022] Figure 6 for Figure 4 A sectional view along line B-B'.

[0023] Explanation of main component symbols: 1-Liquid ammonia tank, 2-First heat exchanger, 3-First buffer device, 4-Absorption tower, 5-Second heat exchanger, 6-Second buffer device, 7-Pressure sensor, 31-Inlet pipe, 32-Distribution pipe, 33-Exhaust pipe, 34-Insulation shell, 61-Buffer chamber, 62-First gas distribution plate, 41-Ammonia release plate, 42-Spray device, 8-Process water pipe, 43-Second gas distribution plate, 21-First heat exchange pipe, 22-Second heat exchange pipe, 51-Third heat exchange pipe, 52-Fourth heat exchange pipe, 9-Heating device, 44-Packing layer, 431-Conical outlet, 432-Liquid collection tank. Detailed Implementation

[0024] This invention provides a food-grade ammonia water production system and method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0025] In the description of this invention, it should be understood that the terms "upper," "lower," "left," and "right," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on the invention. Furthermore, "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "multiple" means two or more.

[0026] Please see Figure 1 and Figure 2The first aspect of the present invention provides a food-grade ammonia water production system, comprising a liquid ammonia tank 1, a first heat exchanger 2, a first buffer device 3, an absorption tower 4, and a second heat exchanger 5 connected in sequence; the first heat exchanger 2 is used to heat liquid ammonia to form ammonia gas; the second heat exchanger 5 is used to cool the ammonia water; an ammonia gas pipeline is provided between the first buffer device 3 and the absorption tower 4, and a pressure sensor 7 is provided on the ammonia gas pipeline; a second buffer device 6 is provided between the pressure sensor 7 and the ammonia gas pipeline; the first buffer device 3 includes an inlet pipe 31, multiple parallel distribution pipes 32, and an exhaust pipe 33 connected in sequence; the diameter of the distribution pipes 32 is smaller than that of the inlet pipe 31 or the exhaust pipe 33. The process flow of the food-grade ammonia water production system of the present invention is as follows: Liquid ammonia supplied by liquid ammonia tank 1 is first heated by the first heat exchanger 2 to vaporize into ammonia gas. During this heat exchange process, the amount of ammonia gas formed is unstable due to factors such as uneven heat exchange, the presence of gas-liquid mixtures, and bends in the pipeline, causing the pressure in the pipeline to fluctuate. At this time, the ammonia gas with unstable pressure passes through the first buffer device 3 and is redistributed by multiple distribution pipes 32. After encountering certain resistance, the ammonia gas passes through multiple distribution pipes 32 again, which play a peak-shaving role. The diverted ammonia gas then converges again to the exhaust pipe 33 and is discharged into the absorption tower 4. The absorption tower 4 is used for the reaction of ammonia gas and water to form ammonia water. In this process, a large amount of heat is released. The high-temperature ammonia water is then cooled by the second heat exchanger 5 and finally sent to the ammonia water storage tank. In this process, pressure sensor 7 is used to detect the pressure value of the ammonia pipeline. The second buffer device 6 further suppresses the pressure change at pressure sensor 7, reduces the fluctuation amplitude, makes the measured pressure value more meaningful, and helps to extend the service life of pressure sensor 7.

[0027] In a preferred embodiment, the sum of the diameters of the multiple distribution pipes 32 is greater than that of the inlet pipe 31 and the exhaust pipe 33, and the diameter of the exhaust pipe 33 is greater than that of the inlet pipe 31. The larger total diameter of the distribution pipes 32 allows the gas to diffuse slowly after entering the distribution pipes 32 from the inlet pipe 31, resulting in a steady decrease in ammonia flow rate and gradual pressure release, avoiding localized high-pressure concentration, and ensuring uniform gas distribution to each distribution pipe 32. The larger diameter of the exhaust pipe 33 ensures that it maintains a low-resistance exhaust state at all times. Even if the intake volume of the inlet pipe 31 increases temporarily due to upstream fluctuations, the larger cross-sectional area of ​​the exhaust pipe 33 results in a smaller pressure increase, preventing significant system pressure fluctuations.

[0028] In a preferred embodiment, the first buffer device 3 is provided with a heat-insulating shell 34. The heat-insulating shell 34 is used to prevent excessive heat exchange between ammonia gas and the outside environment when passing through multiple distribution pipes 32 in a low-temperature environment, which would cause the temperature of the ammonia gas to drop too much.

[0029] Please see Figure 3In a preferred embodiment, the second buffer device 6 is provided with a buffer chamber 61, and a first gas distribution plate 62 is provided in the middle of the buffer chamber 61. The first gas distribution plate 62 has a plurality of through holes evenly distributed on it. Specifically, the upper part of the second buffer device 6 is connected to a pressure sensor 7, and the lower part is connected to an ammonia pipeline. The diameter of the buffer chamber 61 is larger than that of the ammonia pipeline. When ammonia enters the buffer chamber 61 from the ammonia pipeline, if it flows directly upwards, the concentrated airflow at the pipeline outlet can easily form a local high-speed impact flow, causing large fluctuations in the pressure sensor 7 reading. By providing evenly distributed through holes in the first gas distribution plate 62, the concentrated impact airflow can be dispersed into a fine, uniform, low-speed airflow, thus reducing the impact of the instantaneous impact airflow on the pressure sensor 7 reading.

[0030] Please see Figure 1 In a preferred embodiment, an ammonia release plate 41 is provided in the lower part of the absorption tower 4, and multiple release holes are evenly distributed on the ammonia release plate 41. The ammonia release plate 41 is connected to the first buffer device 3 through an ammonia pipeline. Multiple spray devices 42 are provided in the upper part of the absorption tower 4, arranged sequentially from top to bottom. The spray devices 42 are connected to the process water pipeline 8. The bottom of the absorption tower 4 is connected to the second heat exchanger 5. The evenly distributed release holes on the ammonia release plate 41 can disperse the stabilized ammonia gas, preventing excessive local flow velocity of ammonia gas in the absorption tower 4. Inside the absorption tower 4, ammonia gas flows upward from the bottom of the tower, while process water is sprayed downward from the top of the tower, thus achieving countercurrent contact and full contact. By setting up multiple layers of spraying, a stepped absorption can be formed, improving absorption efficiency.

[0031] Please see Figure 1 In a preferred embodiment, a second gas distribution disk 43 is further provided between two adjacent spray devices 42. After the ammonia gas passes through the spray device 42, the distribution of the ammonia gas becomes uneven due to the influence of the process water spray. However, by providing the second gas distribution disk 43, the distribution of the ammonia gas can be made more uniform again, thereby reacting more evenly with the spray process water of the previous layer.

[0032] Please see Figure 1In a preferred embodiment, the first heat exchanger 2 includes a first heat exchange pipe 21 and a second heat exchange pipe 22; the second heat exchanger 5 includes a third heat exchange pipe 51 and a fourth heat exchange pipe 52; the two ends of the first heat exchange pipe 21 are respectively connected to the liquid ammonia tank 1 and the first buffer device 3; the inlet end of the third heat exchange pipe 51 is connected to the bottom of the absorption tower 4, and its outlet end is connected to an ammonia storage tank; the inlet end of the second heat exchange pipe 22 is connected to the outlet end of the fourth heat exchange pipe 52, and its outlet end is connected to a process water recovery device; the inlet end of the fourth heat exchange pipe 52 is connected to a cooling water pipe. During the absorption of ammonia by process water, a large amount of heat is generated. The second heat exchanger 5 cools the ammonia water and absorbs its heat, which keeps the ammonia water stable. Moreover, the water after absorbing heat can ultimately be used to heat the liquid ammonia, reducing subsequent energy consumption.

[0033] Please see Figure 1 In a preferred embodiment, a heating device 9 is further provided between the second heat exchange pipe 22 and the fourth heat exchange pipe 52. In the fourth heat exchange pipe 52, after heat exchange, the water temperature has not yet fully met the requirements for heating liquid ammonia. By supplementing heat through the heating device 9, the water temperature in the second heat exchange pipe 22 can meet the process requirements.

[0034] Please see Figure 1 In a preferred embodiment, a packing layer 44 is disposed above each second gas distribution disk 43. The packing layer 44 is used to form a multi-layer water film, increasing the contact area between ammonia gas and water, and improving absorption efficiency.

[0035] Please see Figure 4-6 In a preferred embodiment, the top surface of the second gas distribution disk 43 is uniformly provided with a plurality of conical gas outlets 431; the top surface of the second gas distribution disk 43 is provided with a plurality of liquid collection grooves 432, and the plurality of conical gas outlets 431 are distributed in the plurality of liquid collection grooves 432. The liquid collection grooves 432 extend downward from the center of the second gas distribution disk 43 towards the edge; a flange extending downward from the center towards the edge is correspondingly formed at the bottom of the liquid collection grooves 432; the flange is located at the bottom of the second gas distribution disk 43. With the packing layer 44 in place, newly formed ammonia water will continuously drip onto the second gas distribution disk 43 below. If it cannot be drained quickly, it will converge from the gas holes in the middle of the second gas distribution disk 43 and flow down, affecting the uniformity of ammonia gas passage. In this embodiment, a liquid collection groove 432 is formed in the second gas distribution disk 43 to guide the dripping ammonia water to the tower wall, so that the ammonia water flows along the tower wall to the bottom of the tower, thereby reducing the impact of dripping liquid on the uniform passage of ammonia gas. The conical vent 431 is narrow at the top and wide at the bottom, which can reduce the amount of ammonia water dripping into the conical vent 431.

[0036] In one specific embodiment, multiple liquid collection tanks 432 are V-shaped and divided into two groups, extending downwards from the left or right side of the middle of the second gas distribution disk 43.

[0037] A second aspect of the present invention provides a method for preparing food-grade ammonia water, wherein food-grade ammonia water is prepared using the food-grade ammonia water production system described above.

[0038] In summary, the present invention reduces pressure fluctuations during the formation of ammonia from liquid ammonia by setting the first buffer device 3 and reduces pressure fluctuations at the detection end of the pressure sensor 7 by setting the second buffer device 6. This results in smaller fluctuations in the pressure detection value of the pressure sensor 7, making the obtained data more valuable and applicable to the subsequent process control of the absorption tower 4.

[0039] Furthermore, the present invention further optimizes the internal structure of the absorption tower 4, making the contact between ammonia and process water more uniform and sufficient, thereby improving absorption efficiency and uniformity.

[0040] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A food-grade ammonia water production system, characterized in that, The system includes a liquid ammonia tank, a first heat exchanger, a first buffer device, an absorption tower, and a second heat exchanger connected in sequence. The first heat exchanger is used to heat the liquid ammonia to form ammonia gas. The second heat exchanger is used to cool the ammonia water. An ammonia gas pipeline is provided between the first buffer device and the absorption tower, and a pressure sensor is provided on the ammonia gas pipeline. A second buffer device is provided between the pressure sensor and the ammonia gas pipeline. The first buffer device includes an intake pipe, multiple parallel distribution pipes, and an exhaust pipe connected in sequence; the diameter of the distribution pipe is smaller than that of the intake pipe or the exhaust pipe. The second buffer device is provided with a buffer cavity, and a first gas distribution plate is provided in the middle of the buffer cavity. Multiple through holes are uniformly provided on the first gas distribution plate. The lower part of the absorption tower is equipped with an ammonia release plate, on which multiple release holes are evenly distributed; the ammonia release plate is connected to a first buffer device; the upper part of the absorption tower is equipped with multiple spray devices, arranged sequentially from top to bottom; the spray devices are connected to process water pipelines; the bottom of the absorption tower is connected to a second heat exchanger; a second gas distribution plate is also provided between two adjacent spray devices; A packing layer is provided above each second gas distribution disk; The top surface of the second gas distribution disk is uniformly provided with a plurality of conical gas outlets; the top surface of the second gas distribution disk is provided with a plurality of liquid collection grooves, and the plurality of conical gas outlets are distributed in the plurality of liquid collection grooves. The liquid collection grooves extend downward at an incline from the center of the second gas distribution disk to the edge; the bottom surface of the liquid collection grooves is correspondingly formed with a flange extending downward at an incline from the center of the second gas distribution disk to the edge; the flange is located on the bottom surface of the second gas distribution disk.

2. The food-grade ammonia water production system according to claim 1, characterized in that, The first buffer device is equipped with an insulated shell.

3. The food-grade ammonia water production system according to claim 1, characterized in that, The first heat exchanger includes a first heat exchange pipe and a second heat exchange pipe; the second heat exchanger includes a third heat exchange pipe and a fourth heat exchange pipe; the two ends of the first heat exchange pipe are respectively connected to a liquid ammonia tank and a first buffer device; the inlet end of the third heat exchange pipe is connected to the bottom of the absorption tower, and its outlet end is connected to an ammonia storage tank; the inlet end of the second heat exchange pipe is connected to the outlet end of the fourth heat exchange pipe, and the outlet end of the second heat exchange pipe is connected to a process water recovery device; the inlet end of the fourth heat exchange pipe is connected to a cooling water pipe.

4. The food-grade ammonia water production system according to claim 3, characterized in that, A heating device is also provided between the second heat exchange pipe and the fourth heat exchange pipe.

5. A method for preparing food-grade ammonia water, characterized in that, Food-grade ammonia water is prepared using the food-grade ammonia water production system as described in any one of claims 1-4.

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