A liquid ammonia vaporizer used in an ammonia refining unit

Abstract

This invention relates to the field of ammonia refining equipment technology, specifically a liquid ammonia vaporizer applied in an ammonia refining unit. It includes a preheating pipe, one end of which is connected to a liquid ammonia inlet, and the other end to a riser pipe. The riser pipe is connected to a distributor, and several injection holes are respectively opened on both sides of the bottom of the distributor. A crushing plate is fixedly installed on both sides of the riser pipe, and several crushing holes are opened on the surface of the crushing plate. In this structure, liquid ammonia first enters the preheating pipe through the liquid ammonia inlet, causing partial vaporization. The partially vaporized liquid ammonia enters the riser pipe, forming a gas-liquid two-phase flow, increasing the liquid ammonia flow rate for further vaporization. Driven by the gas phase, the liquid ammonia is ejected at high speed from the distributor onto the crushing plate. Under the action of the crushing holes, the liquid ammonia is broken into small droplets, which are further vaporized by the rising high-temperature crude ammonia gas, thus achieving a good liquid ammonia vaporization effect.

Description

Technical Field

[0001] This invention relates to the field of ammonia refining equipment technology, specifically a liquid ammonia vaporizer applied in an ammonia refining unit. Background Technology

[0002] Side-stream ammonia extraction and ammonia refining processes are common in acidic water treatment. Acidic water enters the acidic water stripping tower, where it is stripped using low-pressure steam as a heat source in the reboiler at the bottom of the tower. The H2S-containing acidic gas in the acidic water escapes from the top of the tower, while qualified purified water is obtained at the bottom. The ammonia-rich gas extracted from the middle tray of the acidic water stripping tower undergoes three-stage cooling and fractional condensation to obtain crude ammonia gas with an ammonia concentration of over 98% and a temperature of around 40°C, which then enters the ammonia refining section.

[0003] The ammonia refining unit includes an ammonia refining tower, an ammonia crystallizer, and a desulfurization tank (such as...). Figure 1 As shown in the diagram, crude ammonia gas at approximately 40°C needs to be cooled to 5-7°C using the endothermic vaporization of liquid ammonia. In the ammonia refining tower, saturated concentrated ammonia water is used to wash the crude ammonia gas. The ammonia gas exiting the top of the refining tower then enters the ammonia crystallizer, where further vaporization of liquid ammonia lowers the temperature to approximately -5 to -7°C. Hydrogen sulfide in the ammonia gas reacts with the ammonia to form ammonium hydrosulfide crystals, thus removing the hydrogen sulfide from the gaseous ammonia. After this two-stage low-temperature desulfurization process in the ammonia refining tower and crystallizer, the sulfide content in the ammonia gas can reach below 100 ppm. Further adsorption in the desulfurization tank yields high-purity ammonia gas.

[0004] The cooling of crude ammonia in the aforementioned ammonia refining unit fully utilizes the endothermic vaporization principle of liquid ammonia. The vaporization effect and vaporization rate of liquid ammonia are key technologies for the ammonia refining unit. Conventional processes often employ liquid ammonia distribution systems with low vaporization rates and low liquid ammonia utilization, which negatively impacts the energy consumption of the ammonia refining unit. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a liquid ammonia vaporizer for use in an ammonia refining unit.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A liquid ammonia vaporizer for use in an ammonia refining unit includes a preheating pipe, one end of which is connected to a liquid ammonia inlet and the other end of which is connected to a riser pipe. The riser pipe is connected to a distributor, and several injection holes are respectively opened on both sides of the bottom of the distributor. A crushing plate is fixedly installed on both sides of the riser pipe, and several crushing holes are opened on the surface of the crushing plate.

[0007] In the above structure, liquid ammonia first enters the preheating pipe through the liquid ammonia inlet, causing part of the liquid ammonia to vaporize. The partially vaporized liquid ammonia enters the riser pipe, forming a gas-liquid two-phase flow, which increases the flow rate of liquid ammonia for further vaporization. Under the impetus of the gas phase, the liquid ammonia is sprayed at high speed from the distributor onto the crushing plate. Under the action of the crushing holes, the liquid ammonia is broken into small droplets, which are further vaporized by the rising high-temperature crude ammonia gas, thereby achieving a good liquid ammonia vaporization effect.

[0008] The preheating tube is a ring-shaped coil structure, which significantly increases the heat exchange surface area through multi-turn spiral arrangement, allowing for full heat exchange between the liquid ammonia flowing inside the tube and the high-temperature crude ammonia gas outside. This structure not only enhances the heat transfer effect but also promotes the rapid vaporization of liquid ammonia, while optimizing the space utilization of the equipment and significantly improving the overall system thermal efficiency.

[0009] The preheating pipe and the riser pipe are connected by flanges, which not only facilitates disassembly and maintenance but also ensures a reliable connection. In addition, the flange connection allows for a certain degree of installation deviation, making it easy to adjust on-site and highly adaptable.

[0010] The distributor is a hollow tubular structure in which the gas-liquid two-phase flow flows and is further mixed, thereby improving the mass transfer efficiency and avoiding the formation of flow dead zones, thus ensuring the stability and reliability of the process.

[0011] The injection holes on both sides of the distributor are radially offset to avoid affecting the crushing efficiency of the nearby area.

[0012] The central axis of the injection hole is set perpendicular to the crushing plate on the corresponding side, which further improves the crushing effect, increases the surface area and flow rate of liquid ammonia, and performs three-stage vaporization.

[0013] The bottom of the distributor is designed with a concave boss structure, which facilitates the convergence of the gas and liquid phases to both sides of the distributor.

[0014] In application, the liquid ammonia vaporizer is installed inside the ammonia refining tower, and the liquid ammonia inlet extends outside the ammonia refining tower.

[0015] The riser, distributor, and crusher are all located at the top of the preheating pipe, thereby realizing the liquid ammonia vaporization process of preheating vaporization, lifting acceleration, and spraying out crushed vaporization.

[0016] The beneficial effects achieved by this invention are: This invention achieves a highly efficient vaporization process for liquid ammonia through a three-stage vaporization system: 1. The preheating tube adopts a ring coil structure, which increases the heat exchange area to quickly reach the liquid ammonia temperature of -18℃, complete the first vaporization and reach the vaporization equilibrium state. The optimized heat exchange design ensures the maximum vaporization efficiency. 2. The riser can achieve full mixing of the gas and liquid phases, enhance the turbulence effect, accelerate the flow of unvaporized liquid ammonia, and significantly improve the vaporization rate; 3. The concave boss structure at the bottom of the distributor increases the injection speed of incompletely vaporized liquid ammonia to over 8 m / s, ensuring crushing efficiency; the crushing plate can atomize the residual liquid ammonia into extremely small droplets, significantly increasing the specific surface area and flow velocity, achieving efficient tertiary vaporization under low pressure. The synergistic effect of the three-stage vaporization system increases the liquid ammonia vaporization rate to over 98%. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a simplified process flow diagram of an ammonia refining unit in the existing technology; Figure 2 This is a schematic diagram of the liquid ammonia vaporizer of the present invention applied in an ammonia refining tower; Figure 3 This is a schematic diagram of the liquid ammonia vaporizer of the present invention; Figure 4 yes Figure 3 The right view; Figure 5 This is a partial structural schematic diagram (partial cross-sectional view) of the present invention.

[0018] In the diagram: 1. Ammonia refining tower; 2. Preheating pipe; 3. Liquid ammonia inlet; 4. Riser pipe; 5. Distributor; 6. Crushing plate; 7. Injection hole. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] Example: like Figures 2-5 As shown, a liquid ammonia vaporizer used in an ammonia refining unit includes a preheating pipe 2, one end of which is connected to a liquid ammonia inlet 3, and the other end is connected to a riser pipe 4. The riser pipe 4 is connected to a distributor 5. Several injection holes 7 are respectively opened on both sides of the bottom of the distributor 5. A crushing plate 6 is fixedly installed on both sides of the riser pipe 4. Several crushing holes are opened on the surface of the crushing plate 6.

[0021] Liquid ammonia first enters the preheating pipe 2 through the liquid ammonia inlet 3, causing some of the liquid ammonia to vaporize, with a vaporization rate of approximately 14.3%. Partially vaporized liquid ammonia enters riser 4, forming a gas-liquid two-phase flow, increasing the liquid ammonia flow rate for further vaporization; Under the impetus of the gas phase, liquid ammonia is ejected at high speed from the injection hole 7 of the distributor 5 onto the crushing plate 6 (with φ4 small holes). The liquid ammonia is broken into small droplets and further vaporized by the rising high-temperature crude ammonia gas. The concave boss structure at the bottom of the distributor 5 changes the incompletely vaporized liquid ammonia from a continuous flow to an intermittent injection, increasing the injection speed to more than 8 m / s, thus ensuring crushing efficiency.

[0022] The preheating pipe 2 is a ring-shaped coil structure. The multi-turn spiral arrangement significantly increases the heat exchange surface area, allowing for thorough heat exchange between the liquid ammonia flowing inside the pipe and the high-temperature crude ammonia gas outside. This structure not only enhances the heat transfer effect but also promotes the rapid vaporization of liquid ammonia, while optimizing the space utilization of the equipment and significantly improving the overall system's thermal efficiency.

[0023] The preheating pipe 2 and the riser pipe 4 are connected by a flange, which not only facilitates disassembly and maintenance but also ensures a reliable connection. In addition, the flange connection allows for a certain degree of installation deviation, making it easy to adjust on-site and highly adaptable.

[0024] The distributor 5 is a hollow tubular structure. The gas-liquid two-phase flow flows and is further mixed within the distributor 5, thereby improving the mass transfer efficiency and avoiding the formation of flow dead zones, thus ensuring the stability and reliability of the process.

[0025] The injection holes 7 on both sides of the distributor 5 are radially offset to avoid affecting the crushing efficiency of the nearby area.

[0026] The central axis of the injection hole 7 is set perpendicular to the crushing plate 6 on the corresponding side, which further improves the crushing effect, enhances the surface area and flow rate of liquid ammonia, and performs three-stage vaporization.

[0027] The bottom of the distributor 5 is designed with a concave boss structure, which facilitates the convergence of the gas and liquid phases to both sides of the distributor 5.

[0028] like Figure 2 As shown, in application, the liquid ammonia vaporizer is installed inside the ammonia refining tower 1, and the liquid ammonia inlet 3 extends outside the ammonia refining tower 1. The inlet of high-temperature crude ammonia gas is located at the lower part of the liquid ammonia vaporizer.

[0029] The riser 4, distributor 5 and crusher 6 are all located at the upper part of the preheating pipe 2, thereby realizing the liquid ammonia vaporization process of preheating vaporization, lifting acceleration, and spraying out crushing vaporization.

Claims

1. A liquid ammonia vaporizer used in an ammonia refining unit, characterized in that, It includes a preheating pipe (2), one end of which is connected to a liquid ammonia inlet (3), and the other end is connected to a riser pipe (4). The riser pipe (4) is connected to a distributor (5). Several injection holes (7) are opened on both sides of the bottom of the distributor (5). A crushing plate (6) is fixedly installed on both sides of the riser pipe (4). Several crushing holes are opened on the surface of the crushing plate (6). The distributor (5) is a hollow tubular structure. The injection holes (7) on both sides of the distributor (5) are radially offset. The central axis of the injection holes (7) is perpendicular to the crushing plate (6) on the corresponding side. The bottom of the distributor (5) is configured as a concave boss structure; The liquid ammonia in the preheating pipe (2) completes its first vaporization. The riser pipe (4) enables the gas and liquid phases to mix fully, enhancing the turbulence effect and accelerating the flow of the unvaporized liquid ammonia. The concave boss structure at the bottom of the distributor (5) changes the unvaporized liquid ammonia from continuous flow to intermittent injection, increasing the injection speed.

2. The liquid ammonia vaporizer applied in an ammonia refining unit according to claim 1, characterized in that, The preheating pipe (2) has a ring-shaped coil structure.

3. The liquid ammonia vaporizer applied in an ammonia refining unit according to claim 1, characterized in that, The preheating pipe (2) and the riser pipe (4) are connected by a flange.

4. The liquid ammonia vaporizer applied in an ammonia refining unit according to claim 1, characterized in that, The liquid ammonia vaporizer is installed inside the ammonia refining tower (1), and the liquid ammonia inlet (3) extends outside the ammonia refining tower (1).

5. The liquid ammonia vaporizer applied in an ammonia refining unit according to claim 1, characterized in that, The riser (4), distributor (5) and crusher (6) are all located at the upper part of the preheating pipe (2).

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