An apparatus and method for refining and decolorizing liquid ammonia

Abstract

The application discloses a device and method for refining and decoloring liquid ammonia, and belongs to the technical field of liquid ammonia refining and decoloring.The system structure comprises a three-stage condensing device, a water washing tower, a water washing pump, a ceramic membrane filter, a rectifying tower, a fine desulfurization catalyst, a carbon filter, an ammonia gas condenser and a liquid ammonia collecting tank.The three-stage condensing device obtains a first gaseous crude ammonia gas mixture, the water washing tower removes most of hydrogen sulfide in the crude ammonia gas mixture to obtain a high-concentration ammonia water mixture, then the ceramic membrane filter is used to filter and remove organic matters and impurities, the rectifying tower is used for extraction to realize second gaseous phase to obtain higher-purity ammonia gas and a small amount of hydrogen sulfide gas and other impurities, the fine desulfurization catalyst and the carbon filter are used for adsorbing hydrogen sulfide gas and phenols to obtain high-purity ammonia gas, the ammonia gas condenser is used for liquefaction, and the liquid ammonia is stored in the liquid ammonia collecting tank.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid ammonia refining and decolorization, and more particularly relates to a device and method for liquid ammonia refining and decolorization. BACKGROUND

[0002] During the processing of sulfur-containing crude oil, the acid wastewater containing a large amount of ammonia and hydrogen sulfide is generated in the devices such as atmospheric vacuum distillation, catalytic cracking and reforming hydrogenation in a refinery. Therefore, the acid wastewater needs to be pretreated before being discharged into a wastewater treatment plant. In domestic refineries, the ammonia and hydrogen sulfide are separated by using a stripping method, the crude ammonia stripped out is treated by an ammonia refining process to remove hydrogen sulfide impurities, and a high-value-added liquid ammonia product is produced as a byproduct. The liquid ammonia contains impurities, which causes the liquid ammonia to discolor. The impurities contained in the liquid ammonia are mainly free-state Fe 2+ , H2S, phenols, light oil, mercaptans, water and chloride ions.

[0003] At present, the main processes used in China are concentrated ammonia water circulation washing, freezing crystallization and adsorption. The concentrated ammonia water circulation washing and freezing crystallization methods both need to add liquid ammonia to control the temperature and remove hydrogen sulfide, and are not suitable for the process of obtaining ammonia water from the acid wastewater stripping. The adsorption method uses a desulfurizing agent to adsorb hydrogen sulfide in the crude ammonia gas, which is greatly affected by the content of hydrogen sulfide and water in the crude ammonia gas. If the crude ammonia gas after three-stage separation is directly introduced into the adsorber, the desulfurizing agent will be hardened, and the pressure drop will be large. Due to the high content of hydrogen sulfide in the crude ammonia gas, the replacement frequency of the desulfurizing agent will also be high. For the process of obtaining ammonia water from the crude ammonia gas refined by the acid wastewater stripping device, the water washing method is used to remove hydrogen sulfide in the crude ammonia gas in the present application. Although the solubility of ammonia in water is much higher than that of hydrogen sulfide in water, when ammonia is absorbed by water, it quickly becomes ammonia water and ionizes into NH 4+ and OH - , and when hydrogen sulfide is absorbed by water, it immediately ionizes into HS - and H + in the solution. In the alkaline solution, H + reacts with OH - quickly, which causes the hydrogen sulfide in the gas phase to be gradually absorbed by water. SUMMARY

[0004] 1. Technical problems to be solved by the application

[0005] The purpose of the present application is to solve the problem of red discoloration of impure liquid ammonia, the problem of high replacement frequency of the desulfurizing agent, and the problem of insufficient dissolution of the crude ammonia gas in the water washing tower.

[0006] 2. Technical solutions

[0007] To achieve the above purpose, the technical solutions provided by the present application are as follows:

[0008] The application discloses a device for refining and decoloring liquid ammonia, which comprises three-stage condensing devices, a water washing tower, a water washing pump, a ceramic membrane filter, a rectifying tower, a fine desulfurization catalyst, a carbon filter, an ammonia condenser and a liquid ammonia collecting tank connected in sequence.

[0009] Preferably, the water washing tower is provided with a clean water pump and an alkali washing tank at the top, is connected with a crude ammonia pipe and the water washing pump at the bottom, and is internally designed with a demisting layer, a spraying layer and a gas-liquid mixing layer.

[0010] Preferably, the water washing tower comprises gas pipe injection holes and rotary atomizing nozzles, the gas pipe injection holes are arranged on the inner wall of the water washing tower and located at the spraying layer, the gas pipe injection holes are arranged in multiple layers in a circular manner, the gas pipe injection holes and the circular inner wall of the water washing tower are arranged at a certain angle, the gas flow injection direction forms a counterclockwise rotating gas flow in the water washing tower, the rotary atomizing nozzles are arranged on the connecting water pipe in the water washing tower to rotate clockwise, the connecting water pipe is connected with the external clean water pump, and the rotary atomizing nozzles are arranged in multiple groups in a circular manner on the connecting water pipe.

[0011] Preferably, the direct atomizing area of the rotary atomizing nozzles is S1, the injection area of the gas pipe injection holes is S2, and S1>S2.

[0012] Preferably, the bottom of the alkali washing tank is connected with the top of the water washing tower and the inlet of the ceramic membrane filter, the top of the alkali washing tank is connected with the fine desulfurization catalyst, and alkali liquor is added into the alkali washing tank.

[0013] Preferably, the water washing pump is used for transmitting the ammonia water mixture in the water washing tower to the ceramic membrane filter, the ceramic membrane filter has irregular, different-sized and vertically and horizontally intersecting gaps, the gap rate reaches 39%, the ceramic membrane filter has a relatively large permeation throughput, and the ceramic membrane filter has an adsorption effect and can be continuously used by adopting a steam-water backwashing process.

[0014] Preferably, the rectifying conditions of the rectifying tower are as follows: the top temperature is 45-55 DEG C, the bottom temperature is 140-150 DEG C, the pressure is 1.4-1.5 MPa, and the rectifying tower is designed with a one-way communication valve connected to the water washing tower at the bottom.

[0015] Preferably, the fine desulfurization catalyst is internally provided with a desulfurizer for adsorbing trace hydrogen sulfide in ammonia gas, and the carbon filter is internally provided with an active carbon fiber layer.

[0016] A method for refining and decoloring liquid ammonia is provided.

[0017] S100, the crude ammonia gas after three-stage condensation enters the multiple groups of gas pipe injection holes arranged on the inner wall of the water washing tower to form an internal counterclockwise rotating gas flow.

[0018] S200, the rotating atomizing nozzle in the water washing tower rotates clockwise to spray atomized water;

[0019] S300, most of the hydrogen sulfide in the gas phase is gradually absorbed by the atomized water to form a high-concentration ammonia water solution, so that the first desulfurization is realized;

[0020] S400, the water washing pump inputs the high-concentration ammonia water solution into the ceramic membrane filter, the tar in the ammonia water is intercepted, the oil-containing sewage gum is adsorbed on the pipe wall, and the intercepted substances are sequentially intercepted from large to small on the pipe wall, so that the first filtration of organic impurities is realized;

[0021] S500, the high-concentration ammonia water solution enters the rectifying column to rectify and extract ammonia gas according to the different boiling points of various substances, so that the ammonia gas is extracted from the ammonia water gas phase to obtain high-purity ammonia gas;

[0022] S600, the extracted ammonia gas enters the second fine desulfurization catalyst to realize the second fine desulfurization;

[0023] S700, the ammonia gas sequentially enters the carbon filter of the activated carbon fiber layer to remove phenolic impurities in the ammonia gas;

[0024] S800, then the ammonia gas enters the ammonia gas condenser to be liquefied and transported to the liquid ammonia collection tank.

[0025] Preferably, the S100 and S200 crude ammonia gas enters the water washing tower, the crude ammonia gas and the atomized water are fully contacted through reverse convection, a part forms a high-concentration ammonia water solution and enters the ceramic membrane filter, and the other part forms a certain purity ammonia gas and enters the alkali washing tank.

[0026] 3. Beneficial effects

[0027] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0028] (1) The device and method for refining and decolorizing liquid ammonia provided by the present application, the crude ammonia gas is vaporized by a three-stage condensation device, enters a water washing tower to obtain liquefied ammonia water and ammonia gas mixed with hydrogen sulfide, the liquefied ammonia water containing impurities is filtered through a ceramic membrane filter, then is subjected to rectification and stratification vaporization again to extract ammonia gas with higher purity, and after the second fine desulfurization and phenol removal, the liquefied ammonia gas is more pure, and the ammonia gas mixed with hydrogen sulfide is purified by an alkaline tank and then enters a fine desulfurization catalyst and a subsequent filter to obtain pure ammonia gas, so that the purification efficiency is greatly improved through the liquid and gaseous two ways.

[0029] (2) The device and method for refining and decoloring liquid ammonia, the crude ammonia gas forms counterclockwise rotating airflow and the atomized water formed by the rotating atomizing nozzle clockwise rotating injection through the gas pipe injection hole in the water washing tower, the reverse convection collision is formed, the effective combination rate of ammonia water and atomized water is increased, and the injection area S2 of the gas pipe injection hole is smaller than the action area S1 of the rotating atomizing nozzle, so that sufficient adsorption is formed in the first time. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flow structure schematic diagram of the device and method for refining and decoloring liquid ammonia is shown.

[0031] Figure 2 The water washing tower half-section structure schematic diagram of the device and method for refining and decoloring liquid ammonia is shown.

[0032] Figure 3 The water washing tower overhead internal structure schematic diagram of the device and method for refining and decoloring liquid ammonia is shown.

[0033] Figure 4 The working schematic diagram of the rotating atomizing nozzle of the device and method for refining and decoloring liquid ammonia is shown.

[0034] Figure 5 The working schematic diagram of the gas pipe injection hole of the device and method for refining and decoloring liquid ammonia is shown.

[0035] Figure 6 The working process schematic diagram in the water washing tower of the device and method for refining and decoloring liquid ammonia is shown.

[0036] Explanation of the reference numerals in the schematic diagram:

[0037] 100, three-stage condensing device; 200, water washing tower; 300, water washing pump; 400, ceramic membrane filter; 500, rectifying tower; 600, fine desulfurization catalyst; 700, carbon filter; 800, ammonia gas condenser; 900, liquid ammonia collection tank; 201, gas pipe injection hole; 202, rotating atomizing nozzle; 210, clean water pump; 220, alkali washing tank; 510, one-way communication valve. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings, in which several embodiments of the present application are given. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and comprehensive.

[0039] It is to be understood that where an element such as a layer, region or substrate is described as being "on" another element, it can be directly on the other element or intervening elements can also be present. Where an element is described as being "connected" or "coupled" to another element, it can be directly connected or coupled or intervening elements can be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; as used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] Embodiment 1

[0042] Referring to the drawings Figures 1-6 As shown in the drawings, a liquid ammonia refining decolorization device includes a three-stage condensation device 100, a water washing tower 200, a water washing pump 300, a ceramic membrane filter 400, a rectifying tower 500, a fine desulfurization catalyst 600, a carbon filter 700, an ammonia gas condenser 800 and a liquid ammonia collection tank 900 connected in sequence.

[0043] In the above design, the three-stage condensation device 100 vaporizes the acid sewage in layers and transmits it into the water washing tower 200 through the ammonia gas pipeline. At this time, the crude ammonia contains impurities such as ammonia gas and hydrogen sulfide. The water washing tower 200 removes a large amount of hydrogen sulfide in the ammonia gas, and obtains a mixed liquid of ammonia water and hydrogen sulfide water. The ceramic membrane filter 400 removes and filters the organic matter in the mixed liquid, and then enters the rectifying tower 500. The mixed liquid is rectified in layers, and ammonia gas is extracted. At this time, the ammonia gas contains a small amount of hydrogen sulfide, which is adsorbed by the fine desulfurization catalyst 600. After passing through the carbon filter 700 to remove phenolic substances, the final liquid ammonia is obtained by liquefaction through the ammonia gas condenser 800, and the purity of the liquid ammonia is qualified. The liquid ammonia enters the liquid ammonia collection tank 900 for storage.

[0044] It should be noted that the upper end of the water washing tower 200 is connected to the caustic washing tank 220. Most of the ammonia gas at the upper end of the water washing tower 200 enters the caustic washing tank to react with the alkaline solution to remove hydrogen sulfide gas in the ammonia gas to obtain ammonia gas with higher purity, which enters the fine desulfurization catalyst 600 for secondary filtration.

[0045] The top of the water washing tower 200 is provided with a clean water pump 210 and an alkali washing tank 220, the bottom is connected with a crude ammonia pipe and a water washing pump 300, and the inside is designed with a demisting layer, a spraying layer and a gas-liquid mixing layer. The clean water pump 210 is connected with the inside spraying layer of the water washing tower 200 through a connecting water pipe. The design of this structure has two output ways for the ammonia mixed gas filtered by the water washing tower 200, one is to enter the alkali washing tank 220 from the upper end of the water washing tower 200, and the other is to dissolve in water and enter the rectifying tower 500 through the water washing pump. This design can fully extract ammonia from the mixed gas.

[0046] The water washing tower 200 includes a gas pipe injection hole 201 and a rotary atomizing nozzle 202. The gas pipe injection hole 201 is installed on the inner wall of the water washing tower 200 and is located in the spraying layer. The gas pipe injection hole 201 is provided with multiple layers, each layer is installed in a circular arrangement. The gas pipe injection hole 201 and the circular inner wall of the water washing tower 200 are installed at a certain angle. The gas flow injection direction forms a counterclockwise rotating gas flow inside the water washing tower 200. The rotary atomizing nozzle 202 is installed on the connecting water pipe inside the water washing tower 200 and rotates clockwise. The connecting water pipe is connected with the external clean water pump 210. The rotary atomizing nozzle 202 is provided with multiple groups and is installed on the connecting water pipe in a circular arrangement at equal distances. The design of this structure causes the rotary atomizing nozzle 202 to spray atomized water clockwise. The installation position of the gas pipe injection hole 201 and the inner wall of the water washing tower 200 form a certain angle and are arranged in a circle, which causes the sprayed gas to form a counterclockwise rotation at a certain angle. At this time, the counterclockwise rotating gas and the clockwise rotating atomized water form a reverse convection, which increases the effective combination rate of the crude ammonia and the atomized water.

[0047] The direct atomization area of the rotary atomizing nozzle 202 is S1, and the injection area of the gas pipe injection hole 201 is S2, S1>S2. The design of this structure causes the sprayed crude ammonia gas to combine with the atomized water in the first time, forming a sufficient and effective adsorption.

[0048] The bottom of the alkali washing tank 220 is connected with the top of the water washing tower 200 and the inlet of the ceramic membrane filter 400, and the top is connected with the fine desulfurization catalyst 600. Alkali liquor is added into the inside. The design of this structure causes the ammonia gas passing through the top of the water washing tower 200 to contain hydrogen sulfide gas. The hydrogen sulfide gas is removed by using the alkali liquor to obtain pure ammonia gas.

[0049] The water washing pump 300 of the embodiment transports the ammonia water mixture in the water washing tower 200 to the ceramic membrane filter 400. The ceramic membrane filter 400 has irregular, different sizes, vertical and horizontal gaps, and the gap rate reaches 39%. The ceramic membrane filter has a large permeation capacity. The ceramic membrane filter has adsorption effect, and can be continuously used by using the steam water backwashing process. The water washing pump 300 provides the motive power for extracting the ammonia water mixture. The ceramic membrane filter 400 has good filtering and adsorption properties, and removes organic impurities in the ammonia water mixture

[0050] The rectification conditions of the rectification tower 500 are as follows: the top temperature is 45-55°C, the bottom temperature is 140-150°C, and the pressure is 1.4-1.5 MPa. The rectification tower 500 is connected to the water washing tower 200 through the one-way communication valve 510. The design of the rectification tower 500 makes different substances stratify due to different temperature settings of each layer, so that the pure ammonia gas required can be extracted. The one-way communication valve 510 is designed to transport the remaining liquid in the rectification tower 500 back to the water washing tower 200 for recycling.

[0051] The desulfurization catalyst 600 in the embodiment has a desulfurizer for adsorbing trace amounts of hydrogen sulfide in the ammonia gas. The activated carbon fiber layer is installed in the carbon filter 700. The design of the desulfurization catalyst 600 in the embodiment can further remove hydrogen from the two sources of pure ammonia gas. The activated carbon fiber layer has adsorption properties for phenols in the pure ammonia gas.

[0052] A method for refining and decolorizing liquid ammonia, the steps of which are as follows:

[0053] S100, the crude ammonia gas after three-stage fractional condensation enters the multiple groups of gas pipe injection holes 201 installed on the inner wall of the water washing tower 200 to form an internal counterclockwise rotating gas flow;

[0054] S200, the rotating atomizing nozzle 202 in the water washing tower 200 sprays and atomizes water in a clockwise direction;

[0055] S300, most of the hydrogen sulfide in the gas phase is gradually absorbed by the atomized water to form a high-concentration ammonia water solution, realizing the first desulfurization;

[0056] S400, the water washing pump 300 inputs the high-concentration ammonia water solution into the ceramic membrane filter 400. The tar in the ammonia water is intercepted, and the oil-containing sewage gum is adsorbed on the pipe wall. The intercepted substances are sequentially intercepted from large to small on the pipe wall, realizing the first filtration of organic impurities;

[0057] S500, the high-concentration ammonia water solution enters the rectification tower 500 to extract ammonia gas according to the different boiling points of substances, realizing the ammonia water gas phase extraction of high-purity ammonia gas;

[0058] S600, the extracted ammonia gas enters the fine desulfurization catalyst 600 to produce adsorption, realizing the second fine desulfurization;

[0059] S700, the ammonia gas sequentially enters the carbon filter 700 of the activated carbon fiber layer to remove phenolic impurities in the ammonia gas;

[0060] S800, then the ammonia gas enters the ammonia gas condenser 800 for liquefaction and is transported to the liquid ammonia collection tank 900.

[0061] In the embodiment, the S100 and S200 crude ammonia gas enters the water washing tower 200, the crude ammonia gas and the atomized water are fully contacted through reverse convection, a part forms a high-concentration ammonia water solution and enters the ceramic membrane filter 400, and another part forms a certain purity ammonia gas and enters the alkali washing tank 220.

[0062] The above-described embodiments only express certain embodiments of the present application, which are described in detail and specifically, but cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application; therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. An apparatus for refining and decolorizing liquid ammonia, characterized by: It comprises three-stage condensing device (100), water washing tower (200), water washing pump (300), ceramic membrane filter (400), rectifying tower (500), fine desulfurization catalyst (600), carbon filter (700), ammonia condenser (800) and liquid ammonia collection tank (900) connected in sequence; The top of the water washing tower (200) is provided with a clean water pump (210) and an alkali washing tank (220), the bottom is connected with a crude ammonia pipe and a water washing pump (300), and the inside is designed with a demisting layer, a spraying layer and a gas-liquid mixing layer. The water washing tower (200) comprises a gas pipe injection hole (201) and a rotary atomizing nozzle (202), the gas pipe injection hole (201) is installed on the inner wall of the water washing tower (200) and is located in the spraying layer, the gas pipe injection hole (201) is provided with multiple layers, each layer is installed in a circular arrangement, the gas pipe injection hole (201) and the circular inner wall of the water washing tower (200) are installed at a certain angle, the gas flow injection direction forms a counterclockwise rotating gas flow inside the water washing tower (200), and the rotary atomizing nozzle (202) is installed on the connecting water pipe in the water washing tower (200) and rotates clockwise, the connecting water pipe is connected with the external clean water pump (210), and the rotary atomizing nozzle (202) is provided with multiple groups and is installed on the connecting water pipe in a circular arrangement at equal distances.

2. The apparatus for refining and decolorizing liquid ammonia according to claim 1, characterized in that: The direct atomization area of the rotary atomizing nozzle (202) is S1, the injection area of the gas pipe injection hole (201) is S2, and S1>S2.

3. The apparatus for refining and decolorizing liquid ammonia according to claim 1, characterized in that: The bottom of the alkali washing tank (220) is connected with the top of the water washing tower (200) and the inlet of the ceramic membrane filter (400), the top is connected with the fine desulfurization catalyst (600), and the inside is added with alkali liquor.

4. The apparatus for refining and decolorizing liquid ammonia according to claim 1, characterized in that: The water washing pump (300) transmits the ammonia water mixture in the water washing tower (200) to the ceramic membrane filter (400), the ceramic membrane filter (400) has irregular, different sizes and vertical and horizontal intersecting gaps, the gap rate reaches 39%, and the ceramic membrane filter pipe has an adsorption effect and is continuously used by adopting a steam-water backwashing process.

5. The apparatus for refining and decolorizing liquid ammonia according to claim 1, characterized in that: The rectifying conditions of the rectifying tower (500) are that the top temperature is 45°C-55°C, the bottom temperature is 140°C-150°C, and the pressure is 1.4-1.5 MPa, and the rectifying tower (500) is designed with a one-way communication valve (510) connected to the water washing tower (200).

6. The apparatus for refining and decolorizing liquid ammonia according to claim 1, characterized in that: The fine desulfurization catalyst (600) has a desulfurizer for adsorbing trace hydrogen sulfide in ammonia gas, and the carbon filter (700) is provided with an active carbon fiber layer.

7. The method of claim 1, wherein the method is characterized by, The steps are as follows: S100, after three-stage condensation, the crude ammonia gas enters the multiple gas pipe injection holes (201) installed on the inner wall of the water washing tower (200) to form an internal counterclockwise rotating gas flow; S200, the rotary atomizing nozzle (202) in the water washing tower (200) sprays and atomizes water clockwise; S300, most of the hydrogen sulfide in the gas phase is gradually atomized and absorbed by water to form a high-concentration ammonia water solution, realizing the first desulfurization. S400, the water washing pump (300) inputs the high concentration ammonia water solution into the ceramic membrane filter (400), the tar in the ammonia water is intercepted, the oil-containing sewage gelatin is adsorbed on the pipe wall, the intercepted substances are sequentially intercepted from large to small on the pipe wall, and the first filtration of organic impurities is realized; S500, the high concentration ammonia water solution enters the rectifying column (500) to extract ammonia gas according to the different boiling points of various substances, and ammonia gas phase extraction high-purity ammonia gas is realized; S600, the extracted ammonia gas enters the fine desulfurization catalyst (600) to produce adsorption, and the second fine desulfurization is realized; S700, the ammonia gas sequentially enters the carbon filter (700) of the activated carbon fiber layer to remove phenolic impurities in the ammonia gas; S800, then the ammonia gas enters the ammonia gas condenser (800) to be liquefied and transported to the liquid ammonia collecting tank (900).

8. The method of claim 7, wherein: The S100 and S200 crude ammonia gas enters the water washing tower (200), the crude ammonia gas and the atomized water are fully contacted through reverse convection, a part forms a high concentration ammonia water solution and enters the ceramic membrane filter (400), and the other part forms a certain purity ammonia gas and enters the alkali washing tank (220).

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