A sodium hydrosulfide preparation system and a preparation method thereof

Abstract

The present invention particularly relates to a sodium hydrosulfide preparation system and a preparation method, belonging to the technical fields of petrochemical industry and environmental protection. The sodium hydrosulfide preparation system includes a preparation tower: an alkali liquor inlet group is opened in the upper part of the side wall of the preparation tower for introducing alkali liquor into the preparation tower; an acidic gas inlet is opened in the lower part of the side wall of the preparation tower for introducing acidic gas into the preparation tower; a primary alkali liquor outlet is opened at the bottom of the preparation tower; a stripping tower: the upper part of the side wall of the stripping tower is communicated with the primary alkali liquor outlet; a steam inlet is opened in the lower part of the side wall of the stripping tower, and the steam inlet is communicated with a steam source; a product outlet is opened at the bottom of the stripping tower; and an exhaust gas outlet is opened at the top of the stripping tower. It can solve the problem that the prior art cannot directly use the acidic gas of a refinery to produce sodium hydrosulfide.

Description

Technical Field

[0001] The present invention belongs to the technical fields of petrochemical industry and environmental protection, and particularly relates to a sodium hydrosulfide preparation system and a preparation method thereof. Background Art

[0002] At present, there are mainly three common technologies for treating sulfur-containing waste gas, namely, secondary Claus + tail gas hydrogenation reduction + solvent absorption technology, wet sulfuric acid production technology (such as WSA process), and catalytic liquid-phase oxidation technology (such as LO-CAT process); the former includes parts such as CLAUS sulfur production, sulfur degassing and granulation, SCOT tail gas treatment, solvent regeneration, tail gas incineration and flue gas treatment, etc., with a long process flow, complex operation, large investment, and poor scale efficiency; the wet sulfuric acid production technology includes parts such as acidic gas incineration, SCR denitrification, SO2 catalytic conversion, hydration condensation, tail gas treatment, etc., the process of this technology is complex, and the operating conditions are harsh. For example, when the acidic gas is incinerated in the incinerator, the temperature needs to be controlled at 900-1100°C, and the process gas after incineration and removal of NOx must enter a converter equipped with a proprietary catalyst to catalytically convert SO2 into SO3. In addition, this technology cannot produce fuming sulfuric acid with high value, and the economic benefit is poor; the catalytic liquid-phase oxidation technology directly converts hydrogen sulfide into elemental sulfur at room temperature by using a multi-chelate iron catalyst. The acidic gas fully contacts with the absorbent in the absorption chamber and undergoes a chemical reaction. The absorbent after the reaction enters the oxidation chamber through self-circulation, and after contacting with air, a chemical reaction occurs to achieve regeneration, and the regenerated absorbent self-circulates back to the absorption chamber; the elemental sulfur generated by the reaction settles in the conical section at the bottom of the reactor and then goes for dehydration treatment, and the filtrate returns to the absorption / oxidation reactor through a reflux pump. This technology can reduce the hydrogen sulfide in the acidic gas to trace amounts, but the device is prone to defects such as poor quality of refined sulfur color, pipeline corrosion, difficult treatment of sulfur washing water, and difficult treatment of acidic gas containing ammonia during operation.

[0003] For small refineries, chemical plants, and oil and gas field treatment facilities, the treatment volume of sulfur-containing waste gas is relatively small, and there is an urgent need for a treatment process with low equipment and operation costs. Using sulfur-containing waste gas to produce sodium hydrosulfide is an effective measure. The molecular formula of sodium hydrosulfide: NaHS, molecular weight: 56.06; its liquid appearance is colorless or light yellow, greenish yellow or orange red. It is used in the dye industry for synthesizing organic intermediates and preparing auxiliaries for sulfide dyes, in the leather industry for dehairing raw hides and tanning leather, in the fertilizer industry for removing monomer sulfur from activated carbon desulfurizer, in the mining industry for a large amount of copper ore beneficiation, in the production of artificial fibers for sulfurous acid dyeing, etc. At the same time, it is also a raw material for manufacturing ammonium sulfide and semi-finished products of pesticide ethyl mercaptan. Sodium hydrosulfide is also used in wastewater treatment, preparation of polysulfide sodium, sodium thiosulfate, etc., and also has certain uses in the military industry. It is a very widely used chemical raw material.

[0004] The production of sodium hydrosulfide from sulfur-containing waste gas can combine inorganic chemical industry, petroleum refining and environmental protection, greatly reducing the investment and operating costs of sulfur-containing waste gas treatment, and providing a practical new way to solve the problem of sulfur-containing waste gas pollution for small and medium-sized enterprises in remote areas that are unable or do not need to build sulfur recovery units.

[0005] With the changes in domestic and foreign market demands and higher requirements for the quality of sodium hydrosulfide from downstream customers, the current standard GB / T 23937-2020 "Industrial Sodium Hydrosulfide" has put forward higher requirements for the quality of three specifications of sodium hydrosulfide liquid products. Compared with the original GB / T 23937-2009 "Industrial Sodium Hydrosulfide" standard, the mass fractions of sodium hydrosulfide in the three specifications of sodium hydrosulfide liquid products have been increased from 28%, 36%, 42% to 32%, 38%, 43% respectively. For the control index of the mass fraction of sodium sulfide, it remains unchanged at 1.0% in the 32% and 38% specifications of sodium hydrosulfide liquid products, and is reduced from 1.0% to 0.5% in the 43% specification, and control indexes such as sodium carbonate, sodium thiosulfate, sodium sulfite, and iron have been added. With higher requirements for the quality of sodium hydrosulfide, the production technology and methods of sodium hydrosulfide also need to be improved to meet the requirements of GB / T 23937-2020 indicators.

[0006] CN104971597A discloses a process method and device for producing sodium hydrosulfide from acidic gas. The device includes a reaction pipeline. One end of the reaction pipeline is an acidic gas inlet, and the other end is an acidic gas outlet. The reaction pipeline is divided into four-stage reaction zones by setting partitions, which are the first-stage reaction zone, the second-stage reaction zone, the third-stage reaction zone, and the fourth-stage reaction zone in sequence according to the gas flow direction. A liquid phase spraying device is arranged in each stage of the reaction zone, a liquid storage tank is correspondingly arranged below each stage of the reaction zone, a liquid seal assembly is arranged on the upper part of each stage of the liquid storage tank, and each stage of the liquid storage tank is provided with an absorption liquid inlet, a generated liquid outlet, and a circulating liquid outlet. The circulating liquid outlet is connected to the liquid phase spraying device through a pipeline. However, the reaction temperature of the device is relatively high, and the equilibrium partial pressure of hydrogen sulfide in the gas phase increases with the increase of temperature, which will cause the decrease of hydrogen sulfide removal rate. In addition, it will also cause a significant increase in the corrosion of caustic alkali to the equipment.

[0007] The experimental study of preparing sodium hydrosulfide from refinery acid gas in the literature "Experimental Study on Preparing Sodium Hydrosulfide from Refinery Acid Gas" [Wang Faming, Yang Yuqing, Zhang Xiumei, "Shandong Chemical Industry", Vol. 37, No. 5, May 2008] conducts an experimental study on preparing sodium hydrosulfide from refinery acid gas. The experimental device process adopts the principle of amine liquid absorption-regeneration to separate hydrogen sulfide from carbon dioxide first (or called purification and refinement of sulfide gas); the hydrogen sulfide separated from carbon dioxide reacts with sodium hydroxide to generate sodium hydrosulfide. However, this process only pre-treats carbon dioxide in refinery acid gas and does not propose treatment measures for other impurities such as ammonia in it. Moreover, its hydrogen sulfide recovery rate is only 68.58%-97.20% (see Table 4 of this literature), resulting in the volume fraction of hydrogen sulfide in the tail gas (excluding air) being as high as 22.30%-66.81%, which cannot meet the discharge standards. In addition, when treating the acid gas from acid water stripping, operating at a relatively low reaction temperature will cause most of the steam in the acid gas to condense, resulting in excessive dilution of the sodium hydrosulfide product. The overly diluted sodium hydrosulfide product has no sales value and can only be treated as waste.

[0008] Moreover, when the existing technology uses acid gas to prepare sodium hydrosulfide, it is necessary to first concentrate the acid gas to reduce the ammonia or oil impurities in the acid gas, and then the preparation of sodium hydrosulfide can be carried out. The process is cumbersome. In view of this, it is necessary to provide a system and method for producing sodium hydrosulfide that uses refinery acid gas and does not require pre-treatment of impurities such as carbon dioxide, ammonia, hydrocarbons, and water in the acid gas to make up for the deficiencies of the existing technology. Summary of the Invention

[0009] The purpose of the present invention is to provide a sodium hydrosulfide preparation system to solve the problem that the existing technology cannot directly use refinery acid gas to produce sodium hydrosulfide.

[0010] An embodiment of the present invention provides a sodium hydrosulfide preparation system, including: a preparation tower: an alkali liquid inlet group is opened in the upper part of the side wall of the preparation tower for introducing alkali liquid into the preparation tower; an acid gas inlet is opened in the lower part of the side wall of the preparation tower for introducing acid gas into the preparation tower; a primary alkali liquid outlet is opened at the bottom of the preparation tower; a stripping tower: the upper part of the side wall of the stripping tower is connected to the primary alkali liquid outlet; a steam inlet is opened in the lower part of the side wall of the stripping tower, and the steam inlet is connected to a steam source; a product outlet is opened at the bottom of the stripping tower; an exhaust gas outlet is opened at the top of the stripping tower.

[0011] Optionally, a reboiler is provided at the bottom inside the stripping tower. The inlet of the reboiler is connected to the steam source, and the outlet of the reboiler is connected to a first drain pipe.

[0012] Optionally, the steam inlet is connected to the steam source through a first steam pipe, and a first steam valve is provided on the first steam pipe; the inlet of the reboiler is connected to the steam source through a second steam pipe, and a second steam valve is provided on the second steam pipe.

[0013] Optionally, it further includes: an N-stage gas purification unit. The first stage of the N-stage gas purification unit is provided with a primary purified gas inlet, and the primary purified gas inlet is communicated with the top of the preparation tower. The Nth stage of the N-stage gas purification unit is provided with an N-stage purified gas outlet. Wherein: N is at least two and at most six.

[0014] Optionally, each stage of the N-stage gas purification unit is respectively provided with a caustic supply inlet, and a plurality of caustic supply inlets are respectively communicated with a caustic solution source. Each stage of the N-stage gas purification unit is respectively provided with a caustic solution outlet, and a plurality of caustic solution outlets are simultaneously connected to the inlet of a mixer (40). After being mixed in the mixer (40), a first caustic solution is formed, and the first caustic solution is communicated with the caustic solution inlet group on the upper part of the side wall of the preparation tower (10) through the outlet of the mixer (40) for supplying caustic solution to the preparation tower.

[0015] Optionally, the primary caustic solution outlet is communicated with the side wall of the stripping tower through a first shunt pipe and is communicated with the mixer through a second shunt pipe, and a cooler is provided on the second shunt pipe.

[0016] Optionally, a pH detector is provided on the second shunt pipe, an H2S detector is provided at the exhaust port of the Nth stage of the N-stage gas purification unit, and a caustic solution flow control valve is provided at the caustic solution source. The control system of the caustic solution flow control valve is respectively connected to the pH detector and the H2S detector.

[0017] Optionally, the caustic solution inlet group includes a first caustic solution first inlet and a first caustic solution second inlet. The first caustic solution first inlet and the first caustic solution second inlet are arranged on the side wall of the preparation tower from top to bottom. A first caustic supply valve is provided at the first caustic solution first inlet, and a second caustic supply valve is provided at the first caustic solution second inlet.

[0018] Optionally, the first stage of the N-stage gas purification unit is a primary gas purification device. The primary gas purification device is provided with a stirring tank, and a second caustic solution inlet is opened at the top of the stirring tank. The stirring tank is communicated with the caustic solution source through the second caustic solution inlet. The primary purified gas inlet is opened on the lower side wall of the stirring tank. A secondary purified gas outlet is opened at the top of the stirring tank and is communicated with the second stage of the N-stage gas purification unit through the secondary purified gas outlet. A secondary caustic solution outlet is opened at the bottom of the stirring tank, and the stirring tank is communicated with the mixer through the secondary caustic solution outlet.

[0019] Optionally, a distribution pipe is connected to the inside of the primary purified gas inlet. The distribution pipe is annular and is arranged around the stirring shaft of the stirring tank. A plurality of air holes are uniformly opened along the ring of the distribution pipe.

[0020] Optionally, a temperature regulating sleeve is sleeved outside the stirring tank. A temperature regulating cavity is preset in the temperature regulating sleeve. The temperature regulating sleeve is communicated with a second drain pipe and a third steam pipe. A drain valve is provided on the second drain pipe, and the third steam pipe is communicated with a steam source. A third steam valve is provided on the third steam pipe.

[0021] Optionally, the temperature regulating jacket is connected with a circulating water inlet pipe and a circulating water outlet pipe. An inlet valve is provided on the circulating water inlet pipe, and an outlet valve is provided on the circulating water outlet pipe.

[0022] Optionally, the N-stage clean gas unit is a two-stage clean gas unit, and the second stage is a secondary clean gas device: the secondary clean gas device includes a reaction tube arranged vertically. A third caustic liquor inlet is opened at the top of the reaction tube, and the reaction tube is communicated with a caustic liquor source through the third caustic liquor inlet; the secondary purified gas outlet is communicated with the upper part of the reaction tube; a gas-liquid separator is connected to the bottom of the reaction tube, the H2S detector is arranged at the exhaust port at the top of the gas-liquid separator, a third-stage caustic liquor outlet is opened at the bottom of the gas-liquid separator, and the gas-liquid separator is communicated with the mixer through the third-stage caustic liquor outlet.

[0023] An embodiment of the present invention further provides a method for preparing sodium hydrosulfide, which is applicable to the sodium hydrosulfide preparation system described in any one of the above, and includes the following steps:

[0024] Carry out a countercurrent reaction between the acidic gas and the first caustic liquor to obtain a first-stage caustic liquor and a first-stage purified gas;

[0025] Carry out countercurrent steam stripping on the first-stage caustic liquor to obtain a prefabricated liquid and oil ammonia waste gas;

[0026] Concentrate and cool the prefabricated liquid to obtain a sodium hydrosulfide product.

[0027] Optionally, the concentration is: reducing the water content in the prefabricated liquid by boiling evaporation.

[0028] Optionally, it further includes the following steps:

[0029] Divert the first-stage caustic liquor to obtain a first circulating caustic liquor;

[0030] Cool the first circulating caustic liquor and then reflux it as the first part of the first caustic liquor to carry out a countercurrent reaction with the acidic gas.

[0031] Optionally, it further includes the following steps:

[0032] Detect the pH value of the first circulating caustic liquor;

[0033] Adjust the opening degree of the control valve and the reaction time of the countercurrent reaction between the acidic gas and the first caustic liquor according to the pH value of the first circulating caustic liquor.

[0034] Optionally, it further includes the following steps:

[0035] Carry out countercurrent stirring on the first-stage purified gas and the second caustic liquor to obtain a second-stage purified gas and a second circulating caustic liquor;

[0036] Return the second recycled alkaline solution as the second part of the first alkaline solution to react countercurrently with the acid gas.

[0037] Optionally, the method further comprises the following steps:

[0038] React the secondary purified gas and the third alkaline solution in parallel flow and separate the gas and liquid to obtain a tertiary purified gas and a third recycled alkaline solution;

[0039] Return the third recycled alkaline solution as the remaining part of the first alkaline solution to react countercurrently with the acid gas.

[0040] Optionally, the method further comprises the following steps:

[0041] Detect the content of H2S in the tertiary purified gas;

[0042] Adjust the supply amounts of the second alkaline solution and the third alkaline solution according to the content of H2S in the tertiary purified gas.

[0043] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0044] A sodium hydrosulfide preparation system provided by an embodiment of the present invention includes a preparation tower. An alkaline solution inlet group is provided at the upper part of the side wall of the preparation tower, and an acid gas inlet is provided at the lower part of the side wall. The introduced alkaline solution (the first alkaline solution) flows downward, and the introduced acid gas floats upward, so that the two react countercurrently to obtain a semi-finished alkaline solution containing ammonia and oil impurities. By providing a first-stage alkaline solution outlet and connecting a stripping tower to the first-stage alkaline solution outlet, the semi-finished alkaline solution is introduced into the stripping tower, and the semi-finished alkaline solution flows downward in the stripping tower. At the same time, a steam inlet is provided at the lower part of the side wall of the stripping tower, and steam is introduced at the lower part of the stripping tower. The steam floats upward to perform countercurrent stripping with the downward-flowing semi-finished alkaline solution, so as to remove ammonia and oil impurities in the semi-finished alkaline solution and obtain a sodium hydrosulfide product.

[0045] The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. In order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are hereinafter specifically described. Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0047] Figure 1It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 1 of the present invention;

[0048] Figure 2 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 2 of the present invention;

[0049] Figure 3 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 3 of the present invention;

[0050] Figure 4 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 4 of the present invention;

[0051] Figure 5 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 5 of the present invention;

[0052] Figure 6 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 6 of the present invention;

[0053] Figure 7 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 7 of the present invention;

[0054] Figure 8 It is a schematic diagram of the sodium hydrosulfide preparation system provided by Embodiment 8 of the present invention;

[0055] Figure 9 It is a flowchart of the sodium hydrosulfide preparation method provided by the embodiment of the present invention.

[0056] Reference numerals: 10 - preparation tower; 11 - acidic gas inlet; 12 - primary lye outlet; 121 - first shunt pipe; 122 - second shunt pipe; 1221 - cooler; 13 - first inlet of first lye; 131 - first lye supply valve; 14 - second inlet of first lye; 141 - second lye supply valve; 20 - stripping tower; 21 - steam inlet; 211 - first steam pipe; 2111 - first steam valve; 212 - second steam pipe; 2121 - second steam valve; 22 - product outlet; 23 - waste gas outlet; 25 - reboiler; 251 - first drain pipe; 30 - primary gas purification device; 301 - stirring barrel; 3011 - second lye inlet; 3012 - secondary purified gas outlet; 3013 - secondary lye outlet; 302 - temperature regulating jacket; 3021 - third steam pipe; 30211 - third steam valve; 3022 - second drain pipe; 30221 - drain valve; 3023 - circulating water inlet pipe; 30231 - inlet valve; 3024 - circulating water outlet pipe; 30241 - outlet valve; 31 - primary purified gas inlet; 311 - distribution pipe; 40 - mixer; 50 - pH value detector; 51 - H2S detector; 52 - control valve; 60 - reaction tube; 61 - third lye inlet; 62 - gas-liquid separator; 621 - tertiary lye outlet. Detailed Embodiments

[0057] The present invention will be specifically described below in combination with specific embodiments and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0058] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood to have the meanings as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as the general understanding of those skilled in the art to which the present invention pertains. In case of contradiction, this specification shall prevail. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. For example, room temperature may refer to the temperature within the range of 10 to 35 °C.

[0059] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0060] Example 1

[0061] Please refer to Figure 1 , this example provides a sodium hydrosulfide preparation system, including: Preparation tower 10: An alkali liquid inlet group is opened in the upper part of the side wall of the preparation tower 10 for introducing alkali liquid into the preparation tower 10; An acid gas inlet 11 is opened in the lower part of the side wall of the preparation tower 10 for introducing acid gas into the preparation tower 10; A primary alkali liquid outlet 12 is opened at the bottom of the preparation tower 10; Stripping tower 20: The upper part of the side wall of the stripping tower 20 is connected to the primary alkali liquid outlet 12; A steam inlet 21 is opened in the lower part of the side wall of the stripping tower 20, and the steam inlet 21 is connected to a steam source; A product outlet 22 is opened at the bottom of the stripping tower 20; An exhaust gas outlet 23 is opened at the top of the stripping tower 20.

[0062] By providing the preparation tower 10, an alkali liquid inlet group is opened in the upper part of the side wall of the preparation tower 10, and an acid gas inlet 11 is opened in the lower part of the side wall, so that the introduced alkali liquid flows downward and the introduced acid gas floats upward, so that the two react countercurrently to obtain a semi-finished alkali liquid containing ammonia and oil impurities. By opening the primary alkali liquid outlet 12 and providing the stripping tower 20 to be connected to the primary alkali liquid outlet 12, the semi-finished alkali liquid is introduced into the stripping tower 20, and the semi-finished alkali liquid flows downward in the stripping tower 20. At the same time, by opening a steam inlet 21 in the lower part of the side wall of the stripping tower 20 and introducing steam into the lower part of the stripping tower 20, the steam floats upward and countercurrently strips the downward flowing semi-finished alkali liquid, so as to remove ammonia and oil impurities in the semi-finished alkali liquid and obtain a sodium hydrosulfide product free of ammonia and oil impurities.

[0063] The acidic gas may be a gas from the battery limit with a temperature of 10-90°C, a pressure of 0.1-1.1 MPa, and containing components such as hydrogen sulfide, ammonia, water vapor, carbon dioxide, and hydrocarbons. The volume fraction ranges of hydrogen sulfide, ammonia, water vapor, carbon dioxide, and hydrocarbons are 20%-80.0%, 0%-55.0%, 0%-30.0%, 0%-7.5%, and 0%-5.0% respectively.

[0064] The top operating temperature of the preparation tower 10 is 45-95°C, the bottom operating temperature is 45-85°C, and the top operating pressure is -0.1-1.0 MPa.G.

[0065] Example 2

[0066] Please refer to Example 1 Figure 2 , this example provides a sodium hydrosulfide preparation system, which is an improvement over Example 1. The improvement lies in:

[0067] A reboiler 25 is provided at the bottom inside the stripping tower 20. The inlet of the reboiler 25 is connected to a steam source, and the outlet of the reboiler 25 is connected with a first drain pipe 251.

[0068] By arranging the reboiler 25 at the bottom inside the stripping tower 20, the boiling steam formed in the reboiler 25 is used to exchange heat with the semi-finished alkali liquor in the stripping tower 20, so that part of the water in the semi-finished alkali liquor evaporates, thereby realizing the concentration of the semi-finished alkali liquor. Moreover, the evaporated steam can strip ammonia and oil impurities in the semi-finished alkali liquor, and can overcome the problem that the concentration of the sodium hydrosulfide product is further reduced due to partial condensation of the steam introduced into the semi-finished alkali liquor in the solution of Example 1.

[0069] The top operating temperature of the stripping tower 20 is 55-135°C, the bottom operating temperature is 65-145°C, and the top operating pressure is -0.10-0.30 MPa.G;

[0070] Example 3

[0071] Please refer to Example 2 Figure 3 , this example provides a sodium hydrosulfide preparation system, which is an improvement over Example 2. The improvement lies in:

[0072] The steam inlet 21 is connected to a steam source through a first steam pipe 211, and a first steam valve 2111 is provided on the first steam pipe 211; the inlet of the reboiler 25 is connected to the steam source through a second steam pipe 212, and a second steam valve 2121 is provided on the second steam pipe 212.

[0073] By setting the first steam valve 2111 and the second steam valve 2121, the operator can decide which valve to open according to the concentration of the semi-finished caustic liquor. When the concentration of the semi-finished caustic liquor is too low, the first steam valve 2111 is closed and the second steam valve 2121 is opened, and only the reboiler 25 is used for the concentration and stripping of the semi-finished caustic liquor. On the contrary, when the concentration of the semi-finished caustic liquor is too high, the first steam valve 2111 is opened and the second steam valve 2121 is closed, and only the stripping is carried out by introducing steam, while reducing the concentration of the semi-finished caustic liquor.

[0074] It should be noted that through the reasonable control of the two valves, the sodium hydrosulfide preparation system provided by this embodiment can prepare sodium hydrosulfide products with different concentrations to meet different requirements.

[0075] Embodiment 4

[0076] Please refer to this on the basis of Embodiment 3 Figure 4 This embodiment provides a sodium hydrosulfide preparation system, which is an improvement of Embodiment 3. The improvement lies in:

[0077] It further includes: an N-stage clean gas unit: the first stage of the N-stage clean gas unit is provided with a primary clean gas inlet 31, and the primary clean gas inlet 31 is communicated with the top of the preparation tower 10; each stage of the N-stage clean gas unit is respectively provided with a clean gas outlet; where: N is at least two stages and at most six stages.

[0078] Since the primary clean gas is generated during the process of the preparation tower 10 preparing the semi-finished caustic liquor, and the primary clean gas generally does not meet the emission standards, it is necessary to purify the primary clean gas. By setting the N-stage clean gas unit, the primary clean gas is purified in multiple stages so that it can meet the emission standards.

[0079] Specifically, each stage of the N-stage clean gas unit is respectively provided with an alkali supply inlet, and a plurality of alkali supply inlets are respectively communicated with the alkali liquor source; each stage of the N-stage clean gas unit is respectively provided with an alkali liquor outlet, and a plurality of alkali liquor outlets are simultaneously connected to the inlet of the mixer (40). After being mixed in the mixer (40), a first alkali liquor is formed, and the first alkali liquor is communicated with the alkali liquor inlet group on the upper part of the side wall of the preparation tower (10) through the outlet of the mixer (40) for supplying alkali liquor to the preparation tower 10.

[0080] By providing an alkali supply inlet for each stage of the clean gas unit and introducing the alkali liquor into each stage to react with the primary clean gas, harmful substances such as H2S in the primary clean gas are removed, so that it meets the emission standards. And by setting the mixer 40 and a plurality of alkali liquor outlets, the alkali liquor remaining after the reaction in each stage, including the unreacted and incompletely reacted alkali liquor, is introduced into the mixer 40 for mixing, and then supplied to the preparation tower 10 as the first alkali liquor to react with the acidic gas, realizing the full and reasonable recycling of the alkali liquor.

[0081] Preferably, the first-stage lye outlet 12 is communicated with the side wall of the stripping tower 20 through the first shunt pipe 121 and is communicated with the mixer 40 through the second shunt pipe 122. A cooler 1221 is provided on the second shunt pipe 122.

[0082] By providing the first shunt pipe 121 and the second shunt pipe 122, part of the semi-finished lye is used as the recyclable first-circulation lye and mixed with other circulating lye in the mixer 40 to form the first lye for supplying the preparation tower 10. On the one hand, it is to carry out multiple and sufficient reactions between the semi-finished lye and the acid gas to reduce the content of sodium sulfide in the semi-finished lye; on the other hand, the lye in the second shunt pipe 122 is cooled by the cooler 1221, and then the cooled lye is used to cool and control the temperature of the acid gas, so as to flexibly adjust the reaction temperature and meet the requirement of reducing the reaction temperature rise of sodium hydrosulfide (the standard heat of formation of sodium hydrosulfide from hydrogen sulfide and sodium hydroxide is about -14 kcal / mol), which is beneficial to improving the selectivity of sodium hydrosulfide production and enhancing the purity of sodium hydrosulfide products.

[0083] The ratio of the mass flow rate of the first-circulation lye entering the mixer 40 to the sum of the mass flow rates of other circulating lye entering the mixer 40 is 1.0 to 5.0.

[0084] Example 5

[0085] Please refer to the basis of Example 4 Figure 5 , this example provides a sodium hydrosulfide preparation system, which is an improvement of Example 4. The improvement lies in:

[0086] A pH detector 50 is provided on the second shunt pipe 122, an H2S detector 51 is provided at the exhaust port of the Nth stage of the N-stage clean gas unit, and an alkali lye flow control valve 52 is provided at the alkali lye source. The control system of the alkali lye flow control valve 52 is respectively connected to the pH detector 50 and the H2S detector 51.

[0087] By providing the pH detector 50 and the alkali lye flow control valve 52, by detecting the pH value of the lye in the second shunt pipe 122 and the H2S content of the final purified gas discharged from the N-stage clean gas unit, the opening degree of the alkali lye flow control valve 52 is controlled to control the alkali lye flow. When the pH value of the lye in the second shunt pipe 122 is lower than the preset value, the opening degree of the alkali lye flow control valve 52 is increased; when the H2S content of the final purified gas discharged from the N-stage clean gas unit is higher than the preset value, the opening degree of the alkali lye flow control valve 52 is increased.

[0088] More specifically, when the pH value < 9, the control valve 52 is opened wider to increase the feed rate of the lye. When the pH value > 11, the control valve 52 is closed slightly to reduce the lye feed rate, ensuring that the pH value of the lye in the second shunt pipe 122 is within the range of 9 - 11. The reason is that if the pH value is higher than 11 at the reaction temperature, part of the HS - is converted to S 2- , causing the Na2S content in the NaHS product to exceed the standard. If the pH value is less than 9 at the reaction temperature, there will be problems of reduced H2S conversion rate and carbonate crystal precipitation. When the H2S content of the final purified gas discharged from the N-stage clean gas unit is greater than the required target value (for example, the required target value can be 10 mg / m 3 , or it can also be 400 mg / m 3 ), the control valve 52 is opened wider to increase the lye feed rate until the operating condition is restored.

[0089] It should be noted that the pH detector 50 and the H2S detector 51 have priorities, and the priority of the H2S detector 51 is higher than that of the pH detector 50. As long as the H2S content is higher than the preset value, the H2S detector 51 will override and control the opening of the lye flow control valve 52 to increase the lye flow rate from the lye source until the H2S content is lower than the preset value.

[0090] The lye source is sodium hydroxide solution, and the mass fraction of sodium hydroxide in the sodium hydroxide solution is controlled within the range of 15% - 50%, with a pressure of 0.1 - 1.2 MPa and a temperature of 10 - 60 °C.

[0091] Example 6

[0092] On the basis of Example 5, please refer to Figure 6 . This example provides a sodium hydrosulfide preparation system, which is an improvement over Example 5. The improvement lies in:

[0093] The lye inlet group includes a first lye first inlet 13 and a first lye second inlet 14. The first lye first inlet 13 and the first lye second inlet 14 are arranged vertically on the side wall of the preparation tower 10 from top to bottom. The first lye first inlet 13 is provided with a first lye supply valve 131, and the first lye second inlet 14 is provided with a second lye supply valve 141.

[0094] By setting that the lye inlet group includes a first lye first inlet 13 and a first lye second inlet 14, and the two are arranged from top to bottom, and by setting a first lye supply valve 131 and a second lye supply valve 141, the distance of the countercurrent reaction between the lye and the sour gas is adjusted according to the carbon dioxide content in the sour gas. Specifically, when the mass fraction of carbon dioxide in the sour gas > 5%, the first lye supply valve 131 is closed, the second lye supply valve 141 is opened, the contact time between carbon dioxide and the gas-liquid interface is shortened, and the chance of carbon dioxide penetrating through the gas-liquid interface to react with the lye is reduced, which is beneficial to reducing the generation amount of sodium bicarbonate and sodium carbonate.

[0095] Example 7

[0096] On the basis of Example 6, please refer to Figure 7 , this example provides a sodium hydrosulfide preparation system, which is an improvement of Example 6. The improvement lies in:

[0097] The first stage of the N-stage purified gas unit is a first-stage purified gas device 30: The first-stage purified gas device 30 is provided with a stirring barrel 301. A second lye inlet 3011 is opened at the top of the stirring barrel 301. The stirring barrel 301 is communicated with a lye source through the second lye inlet 3011; A first-stage purified gas inlet 31 is opened on the lower side wall of the stirring barrel 301; A second-stage purified gas outlet 3012 is opened at the top of the stirring barrel 301, and is communicated with the second stage of the N-stage purified gas unit through the second-stage purified gas outlet 3012; A second-stage lye outlet 3013 is opened at the bottom of the stirring barrel 301. The stirring barrel 301 is communicated with a mixer 40 through the second-stage lye outlet 3013.

[0098] By arranging a stirring barrel 301 in the first-stage purified gas device 30, the reaction efficiency and sufficiency of the first-stage purified gas and the lye are improved by means of stirring, and part of the sodium sulfide crystals can be allowed to suspend in the solution and contact with H2S gas at a relatively high pH value, which can effectively reduce the adverse effects brought by the crystallization of sodium sulfide and the like.

[0099] Furthermore, a distribution pipe 311 is connected to the inner side of the first-stage purified gas inlet 31. The distribution pipe 311 is annular and is arranged around the stirring shaft of the stirring barrel 301. A plurality of air holes (not shown in the figure) are uniformly opened along the ring of the distribution pipe 311.

[0100] By arranging the distribution pipe 311 to be annular, arranging it around the stirring shaft, and opening a plurality of air holes thereon, the first-stage purified gas is uniformly introduced into the stirring barrel 301 through the air holes, thereby improving the reaction efficiency.

[0101] Preferably, the diameter of the distribution pipe 311 is designed according to 0.15 - 0.25 of the inner diameter of the stirring barrel 301. The number of air holes is 3 - 15, and the diameter of the air holes is 8 - 20 mm.

[0102] Further preferably, when the carbon dioxide content in the primary purified gas > 5%, the distribution pipe can be set as a straight pipe, the number of pores is 3 - 6, and the pore distribution range is less than the diameter of the stirring blade of the stirring tank 301 to ensure that the primary purified gas is discharged at the lower position of the blade; the diameter of the pores is 15 - 25 mm.

[0103] Furthermore, a temperature regulating sleeve 302 is provided outside the stirring tank 301. A temperature regulating cavity is preset in the temperature regulating sleeve 302. The temperature regulating sleeve 302 is connected to a second drain pipe 3022 and a third steam pipe 3021. The second drain pipe 3022 is provided with a drain valve 30221. The third steam pipe 3021 is connected to a steam source, and the third steam pipe 3021 is provided with a third steam valve 30211.

[0104] By providing the temperature regulating sleeve 302 and setting the second drain pipe 3022, the third steam pipe 3021, the drain valve 30221 and the third steam valve 30211, it is used to raise the reaction temperature in the stirring tank 301. When the temperature is lower than the preset temperature range, the third steam valve 30211 and the drain valve 30221 are opened, and hot steam is introduced into the temperature regulating cavity of the temperature regulating sleeve 302, thereby raising the temperature of the stirring tank 301 through heat exchange.

[0105] Furthermore, the temperature regulating sleeve 302 is connected to a circulating water inlet pipe 3023 and a circulating water outlet pipe 3024. The circulating water inlet pipe 3023 is provided with a water inlet valve 30231, and the circulating water outlet pipe 3024 is provided with a water outlet valve 30241.

[0106] By providing the circulating water inlet pipe 3023, the circulating water outlet pipe 3024, the water inlet valve 30231 and the water outlet valve 30241, it is used to lower the reaction temperature in the stirring tank 301. When the temperature is higher than the preset temperature range, the water inlet valve 30231 and the water outlet valve 30241 are opened, and cold water is introduced into the temperature regulating cavity of the temperature regulating sleeve 302, thereby lowering the temperature of the stirring tank 301 through heat exchange.

[0107] The operating temperature of the primary gas purification device 30 is 40 - 60 °C, and the operating pressure is -0.10 - 1.0 MPa; and the other main parameters of the primary gas purification device 30 are as follows:

[0108] The height-diameter ratio of the stirring tank is 0.8 - 2.8, and it is preferably 1 - 1.5;

[0109] The ratio of the diameter of the stirrer to the inner diameter of the stirring tank is 0.25 - 0.45, and it is preferably 0.30 - 0.40;

[0110] The distance from the center line of the stirrer to the bottom of the stirring tank can be 0.70 - 0.80 times the diameter of the stirrer, preferably 0.75;

[0111] The rotation speed of the stirrer is 0.5 - 4.5 r / s, preferably 1.0 - 2.0 r / s;

[0112] The ratio of the blade width to the agitator diameter is 0.15 - 0.25, preferably 0.20;

[0113] The processing capacity of the mixing tank: designed according to 10 - 200 Nm 3 of caustic solution per 1 m 3 in the mixing tank for the first-stage purified gas per hour;

[0114] Preferably, one agitator is arranged in the mixing tank. When the ratio of the liquid level height in the mixing tank to the inner diameter of the mixing tank exceeds 1.0, two agitators are arranged at different positions on the stirring shaft; when the ratio of the liquid level height in the mixing tank to the inner diameter of the mixing tank exceeds 1.6, three agitators are arranged at different positions on the stirring shaft. The above parameter combination is beneficial to improving the selectivity of sodium hydrosulfide production and enhancing the purity of sodium hydrosulfide products.

[0115] Example 8

[0116] On the basis of Example 7, refer to Figure 8 , this example provides a sodium hydrosulfide preparation system, which is a specific limitation of Example 7. The limitation lies in:

[0117] The N-stage purified gas unit is a two-stage purified gas unit, and the second stage is a secondary purified gas device: the secondary purified gas device includes a reaction tube 60 arranged vertically. A third caustic solution inlet 61 is opened at the top of the reaction tube 60. The reaction tube 60 is communicated with the caustic solution source through the third caustic solution inlet 61; the secondary purified gas outlet 3012 is communicated with the upper part of the reaction tube 60; a gas-liquid separator 62 is connected to the bottom of the reaction tube 60. The H2S detector 51 is arranged at the exhaust port at the top of the gas-liquid separator 62. A tertiary caustic solution outlet 621 is opened at the bottom of the gas-liquid separator 62. The gas-liquid separator 62 is communicated with the mixer 40 through the tertiary caustic solution outlet 621.

[0118] The length / diameter ratio (L / D) of the reaction tube 60 is controlled within the range of 3 - 15, and the gas-liquid volume ratio is controlled within the range of 3 - 10; the apparent linear velocity of the mixture composed of the secondary purified gas and the tertiary caustic solution is controlled within 0.5 - 10.0 m / s; the contact time of the gas-liquid two-phase in the tertiary reactor is controlled within the range of 0.05 - 2.50 seconds.

[0119] After the above measures are taken, the H2S content in the tertiary purified gas ≤ 1.0 mg / Nm 3 or meets the requirements of specific emission standards. For example, the emission index after incineration treatment of the tertiary purified gas can meet the requirement that the SO2 content in the flue gas discharged from the "Pollutant Discharge Standard for the Petroleum Refining Industry" (GB31570 - 2015) ≤ 400 mg / Nm 3 or meets the requirement of the special emission limit SO2 content ≤ 100 mg / Nm 3 requirement.

[0120] Please refer to Figure 9 , this embodiment provides a method for preparing sodium hydrosulfide, which is applicable to any of the above sodium hydrosulfide preparation systems, and includes the following steps:

[0121] S1. React the acid gas with the first alkaline solution in a countercurrent manner to obtain a first-stage alkaline solution and a first-stage purified gas, using the preparation tower 10.

[0122] S2. Stripping the first-stage alkaline solution with steam in a countercurrent manner to obtain a prefabricated solution and oil ammonia waste gas, using the stripping tower 20.

[0123] S3. Concentrate and cool the prefabricated solution to obtain sodium hydrosulfide products, using the stripping tower 20.

[0124] Through step S1, the acid gas containing hydrogen sulfide, carbon dioxide, water vapor, or ammonia, hydrocarbons, etc. reacts with the first alkaline solution containing sodium sulfide, sodium hydrosulfide, and sodium hydroxide (the first alkaline solution is obtained by mixing the respective circulating alkaline solutions at the outlet of the subsequent N-stage purified gas units and the first circulating alkaline solution in the mixer (40)) in a countercurrent manner to obtain a first-stage alkaline solution. The main reaction formulas are as follows:

[0125] H2S(aq)+2NaOH(aq)→Na2S(aq)+2H2O (1)

[0126] H2S(aq)+Na2S(aq)→2NaHS(aq) (2)

[0127] Reaction (1) and reaction (2) respectively generate sodium sulfide and sodium hydrosulfide; among them, reaction (2) for generating sodium hydrosulfide is the main reaction.

[0128] In addition, when the acid gas contains carbon dioxide, the following side reactions will also occur:

[0129] CO 2(aq) +NaOH (aq) →NaHCO 3(aq) (3)

[0130] NaHCO 3(aq) +NaOH (aq) →Na2CO 3(aq) +H2O (4)

[0131] Reaction (3) and reaction (4) will not only increase the consumption of the alkaline solution and cause a large amount of waste alkaline solution to be generated, but also the generated carbonates will pollute the quality of the sodium hydrosulfide products. In addition, the carbonates are easy to crystallize into solids, causing blockage of process pipelines and equipment. Therefore, it is very important to improve the absorption selectivity of hydrogen sulfide and reduce the generation of carbonates.

[0132] Reaction (1) and reaction (2) have faster reaction rates because H2S transfers faster at the gas-liquid interface and in the liquid phase. Reaction (3) and reaction (4) have slower reaction rates because CO2 first enters the gas film from the gas phase, then enters the liquid film through the gas-liquid interface, and then enters the liquid phase to react with OH. - Reaction to form HCO3 - Ions, HCO3 - The ions then react with NaOH, and the reaction of CO2 with NaOH is a slow reaction controlled by the liquid membrane; the difference in the reaction rates of NaOH to H2S and CO2 can be used to improve the purity of sodium hydrosulfide in the sodium hydrosulfide product of the present invention. Specifically, measures such as changing the contact time and contact area of ​​H2S and CO2 with the NaOH solution can be taken to improve the selective absorption capacity of the NaOH solvent, so that NaOH is conducive to the absorption reaction of H2S, but not conducive to the absorption reaction of CO2.

[0133] Since reactions (1) to (4) are all exothermic reactions, a higher reaction temperature is not conducive to the absorption of H2S and CO2 by the NaOH solution, but is even more not conducive to the formation of sodium carbonate and sodium bicarbonate. Therefore, under the premise of meeting the quality requirements of sodium hydrosulfide products and purified gas emission requirements, when the CO2 content in the acid gas is high, the reaction temperature implemented in the present invention is correspondingly increased to reduce the formation rate of sodium carbonate and sodium bicarbonate and avoid the formation of carbonate crystals in the NaOH solution.

[0134] Through step S2, ammonia and oil impurities in the primary alkali solution are removed.

[0135] Through step S3, a sodium hydrosulfide product having a composite concentration requirement and not containing ammonia and oil impurities is obtained.

[0136] Preferably, the concentration comprises: reducing the water content in the preformed liquid by boiling evaporation.

[0137] Furthermore, the method further comprises the following steps:

[0138] S2.1. Divert the primary alkali solution to obtain the first circulation alkali solution.

[0139] S2.2, refluxing the first circulating alkali solution as the first part of the first alkali solution to react with the acid gas in countercurrent.

[0140] The mechanism and effect of steps S2.1 and S2.2 are shown in Example 4.

[0141] Furthermore, the method further comprises the following steps:

[0142] S2.3, detecting and obtaining the pH value of the first cycle of alkali solution.

[0143] S2.4. Adjust the opening degree of the control valve and the reaction time of the countercurrent reaction between the acid gas and the first lye according to the pH value of the first circulating lye.

[0144] S2.5. Detect the content of H2S in the tertiary purified gas.

[0145] S2.6. Adjust the supply amounts of the second lye and the third lye according to the content of H2S in the tertiary purified gas.

[0146] For the mechanism and effects of steps S2.3 - S2.6, see Example 5.

[0147] Further, the following steps are further included:

[0148] S4. Stir the primary purified gas and the second lye countercurrently to obtain the secondary purified gas and the second circulating lye;

[0149] S5. Return the second circulating lye as the second part of the first lye to react countercurrently with the acid gas.

[0150] S6. React the secondary purified gas and the third lye in parallel flow and separate the gas and liquid to obtain the tertiary purified gas and the third circulating lye;

[0151] S7. Return the third circulating lye as the remaining part of the first lye to react countercurrently with the acid gas.

[0152] For the mechanism and effects of steps S5 - S7, see Example 4.

[0153] Example 9

[0154] This example provides a method for preparing sodium hydrosulfide, which is carried out using the sodium hydrosulfide preparation system provided in Example 8, specifically as follows.

[0155] Using the sodium hydrosulfide preparation system as Figure 8 shown, acid gas at a temperature of 85.0°C, a pressure of 170 kPa.A, and a flow rate of 118.00 kg / h (5.7056 kmol / h) (the flow rate and composition are shown in Table 1) and lye with a mass fraction of 40% (the flow rate and composition are shown in Table 1) are used as raw materials to produce sodium hydrosulfide. The acid gas first enters the preparation tower 10 through the acid gas inlet 11. The lye at a temperature of 45.5°C and a pressure of 200 kPa.A from the first inlet 13 of the first lye enters the preparation tower 10, contacts the acid gas countercurrently, absorbs 49.07% of the total hydrogen sulfide contained in the acid gas, and then the temperature rises to 61.4°C. Then it enters the buffer tank at the bottom of the preparation tower 10 as the primary lye for buffering, and is then boosted to 270 kPa.A by the circulation pump and divided into the first circulating lye and the semi-finished lye. The acid gas discharged from the top of the preparation tower 10 enters the stripping tower 20 as the primary purified gas to further remove hydrogen sulfide.

[0156] The operating conditions for the preparation tower 10 are as follows: the top operating temperature is 71.3 °C, the bottom operating temperature is 61.4 °C, and the top operating pressure is 70 kPa.A; the ratio of the mass flow rate of the first circulating alkali solution to the sum of the mass flow rates of other circulating alkali solutions is 1.333; the preparation tower 10 is provided with two reaction bed layers in total (corresponding to the first alkali solution first inlet 13 and the first alkali solution second inlet 14 respectively), and both the first bed layer and the second bed layer are packed beds, and the height of the packed bed sections is 2 m each; the bed diameter is 0.5 m; the inner diameter and length of the buffer tank at the lower part of the preparation tower 10 are 1.2 m and 4.8 m respectively.

[0157] The semi-finished alkali solution obtained by the first-stage alkali solution shunt enters the stripping tower 20. By means of direct steam stripping (opening the first steam valve 2111 and closing the second steam valve 2121), impurities such as ammonia and oil carried by it are stripped out, and finally a sodium hydrosulfide liquid product with a mass flow rate of 169.37 kg / h and a mass fraction of 36.1384% is obtained (the flow rate and composition are shown in Table 1), and its various indicators meet the quality requirements of the sodium hydrosulfide liquid product of the 32% specification in GB / T 23937-2020 "Industrial Sodium Hydrosulfide"; waste gas with a mass flow rate of 67.68 kg / h and an ammonia mass fraction of 11.0186% is stripped out from the waste gas outlet 23 at the top of the stripping tower 20 (the flow rate and composition are shown in Table 1), and this waste gas can be subjected to high-temperature incineration treatment.

[0158] The operating conditions for the stripping tower 20 are as follows: the top operating temperature is 112.8 °C, and the top operating pressure is 150 kPa.A; there is one packed bed section inside the tower, and the height of the packed bed section is 3 m.

[0159] The primary purified gas coming from the top of the preparation tower 10 enters the bottom of the stirring tank 301 and contacts with the second alkali solution coming from the second alkali solution inlet 3011 at the top of the stirring tank 301 to further remove hydrogen sulfide in it. The primary purified gas is introduced into the stirring tank 301 through the distribution pipe 311 below the stirrer.

[0160] The operating temperature of the stirring tank 301 is 50 °C, and the operating pressure is 60 kPa.A. The operating temperature of the secondary reactor is strictly controlled by means of split-range control of steam heating and circulating cold water cooling. When the operating temperature is lower than 50 °C, the temperature regulator TC-01 opens the third steam valve 30211 and the drain valve 30221, closes the water inlet valve 30231 and the water outlet valve 30241, and steam enters the temperature regulating jacket 302 through the third steam valve 30211 to heat the materials in the stirring tank 301; when the operating temperature is higher than 50 °C, the temperature regulator TC-01 opens the water inlet valve 30231 and the water outlet valve 30241, closes the third steam valve 30211 and the drain valve 30221, and circulating cold water enters the temperature regulating jacket 302 from the water inlet valve 30231 to cool the materials in the stirring tank 301, and the circulating hot water is discharged through the water outlet valve 30241.

[0161] The main parameters of the stirring tank 301 are as follows:

[0162] Diameter: 1.2 m;

[0163] Tangent height: 1.5 m;

[0164] Diameter of the agitator: 0.40 m;

[0165] Distance from the center line of the agitator to the bottom of the stirring tank 301: 0.3 m;

[0166] Rotational speed of the agitator: 1.5 r / s;

[0167] Width of the blade: 0.08 m;

[0168] One agitator is adopted;

[0169] The gas product of the stirring tank 301 is discharged as the secondary purified gas from the secondary purified gas outlet 3012. The mass fraction of hydrogen sulfide in the secondary purified gas is 3.4044%. Then it enters the reaction tube 60 to contact with the third lye for a deep desulfurization reaction of hydrogen sulfide. To avoid excessive carbon dioxide being absorbed into the third lye, the gas-liquid contact time in the reaction tube 60 is optimized and controlled within the range of 0.50 - 1.50 s.

[0170] The reaction tube 60 preferably selects an SV type static mixer, with its length / diameter ratio (L / D) set to 10, and the gas-liquid volume ratio controlled within the range of 3 - 10; the superficial linear velocity of the mixture composed of the secondary purified gas and the third lye is controlled within the range of 0.5 - 10.0 m / s.

[0171] The reaction tube 60 is selected to be installed vertically to make the secondary purified gas and the third lye flow vertically downward. The gas-liquid mixture at the bottom outlet of the reaction tube 60 directly enters the gas-liquid separator 62 for gas-liquid separation. The gas is used as the tertiary purified gas, and the waste gas with a mass flow rate of 54.54 kg / h and a hydrogen sulfide mass fraction of 0.0083% (the flow rate and composition are shown in Table 1), with an average molecular weight of 17.30, can be discharged to the incinerator for incineration or be uniformly treated by the whole plant.

[0172] The liquid product of the stirring tank 301 is discharged as the second circulating lye from the secondary lye outlet 3013. After mixing with the third circulating lye separated from the bottom of the gas-liquid separator 62, it enters the inlet of the booster pump. After being boosted to 270 kPa.A by the booster pump, it is mixed with the first circulating lye in the mixer 40. The first lye at the outlet of the mixer 40 enters the preparation tower 10 through the first inlet 13 of the first lye to realize the lye circulation.

[0173] In order to ensure that the specifications of the sodium hydrosulfide products produced and the hydrogen sulfide content in the third-stage purified gas discharged meet the requirements, the present invention is provided with a pH detector 50 (AC-01) and an H2S detector 51 (AC-02), and a high-selectivity control system FY-01 is set up. During normal production, the inlet volume of the lye source is controlled by the value of AC-01. When the pH value < 9, the control valve 52 is opened wider to increase the lye feed volume. When the pH value > 11, the control valve 52 is closed smaller to reduce the lye feed volume, ensuring that the pH value of the first-cycle lye is within the range of 9-11; when the hydrogen sulfide mass fraction of the third-stage purified gas measured by AC-02 > 0.01%, its output signal is transmitted to the high-selector FY-01, so that the control system automatically switches to the hydrogen sulfide content control system, and the control valve 52 is opened wider to increase the lye feed volume. When the working condition is restored, it automatically switches back to the original control system. The properties such as temperature, pressure, and composition of the materials entering and leaving the device are shown in Table 1.

[0174] Table 1 Properties of Main Logistics

[0175]

[0176]

[0177] Table 1 Properties of Main Logistics (continued)

[0178]

[0179] As can be seen from Table 1, the sodium hydrosulfide preparation system and method provided by the embodiments of the present invention can directly prepare sodium hydrosulfide products that meet the requirements by using acid gas and lye, and the waste gas and the third-stage purified gas generated meet the requirements of the emission standards after incineration treatment. It can also be seen from Table 1 that the sodium hydrosulfide preparation system and method provided by the embodiments of the present invention, the preparation tower 10, the stirring tank 301, and the reaction tube 60 can all operate under negative pressure, avoiding the possibility of hydrogen sulfide gas leakage when the pressure is higher than the atmospheric pressure, which is conducive to the safe operation of operators and environmental protection.

[0180] Example 10

[0181] This embodiment provides a method for preparing sodium hydrosulfide, which is carried out by using the sodium hydrosulfide preparation system provided in Example 9, specifically as follows.

[0182] The operating conditions for preparing column 10 are as follows: the top operating temperature is 65.2 °C, and the bottom operating temperature is 55.6 °C; the ratio of the mass flow rate of the first recycled lye to the sum of the mass flow rates of other recycled lye is 4.0; the semi-finished lye obtained by splitting the primary lye enters the stripping column 20, and the impurities such as ammonia and oil carried by it are stripped out by indirect steam stripping using a reboiler 25 (closing the first steam valve 2111 and opening the second steam valve 2121), and part of the water is evaporated; other conditions are the same as those in Example 9;

[0183] Finally, a sodium hydrosulfide liquid product with a mass flow rate of 142.57 kg / h and a mass fraction of 43.22% is obtained, and a tertiary purified gas with a mass flow rate of 53.21 kg / h and a hydrogen sulfide mass fraction of 0.0010% is obtained.

[0184] Finally, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0185] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0186] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A sodium hydrosulfide preparation system, characterized in that, Including: Preparation tower (10): An alkali solution inlet group is provided in the upper part of the side wall of the preparation tower (10) for introducing alkali solution into the preparation tower (10); an acid gas inlet (11) is provided in the lower part of the side wall of the preparation tower (10) for introducing acid gas into the preparation tower (10); a primary alkali solution outlet (12) is provided at the bottom of the preparation tower (10). Stripping tower (20): The upper part of the side wall of the stripping tower (20) is communicated with the primary alkali solution outlet (12); a steam inlet (21) is provided in the lower part of the side wall of the stripping tower (20), and the steam inlet (21) is communicated with a steam source; a product outlet (22) is provided at the bottom of the stripping tower (20); an exhaust gas outlet (23) is provided at the top of the stripping tower (20). A reboiler (25) is provided at the inner bottom of the stripping tower (20), the inlet of the reboiler (25) is communicated with the steam source, and the outlet of the reboiler (25) is connected with a first drain pipe (251). The steam inlet (21) is communicated with the steam source through a first steam pipe (211), and a first steam valve (2111) is provided on the first steam pipe (211); the inlet of the reboiler (25) is communicated with the steam source through a second steam pipe (212), and a second steam valve (2121) is provided on the second steam pipe (212).

2. The sodium hydrosulfide preparation system according to claim 1, wherein Also including: N-stage clean gas unit: A primary purified gas inlet (31) is provided at the first stage of the N-stage clean gas unit, and the primary purified gas inlet (31) is communicated with the top of the preparation tower (10); a purified gas outlet is provided at each stage of the N-stage clean gas unit. Wherein: N is at least two and at most six.

3. The sodium hydrosulfide preparation system according to claim 2, characterized in that, A supply alkali inlet is provided at each stage of the N-stage clean gas unit, and the multiple supply alkali inlets are respectively communicated with an alkali solution source; an alkali solution outlet is provided at each stage of the N-stage clean gas unit, and the multiple alkali solution outlets are simultaneously connected to the inlet of a mixer (40). After being mixed in the mixer (40), a first alkali solution is formed, and the first alkali solution is communicated with the alkali solution inlet group on the upper part of the side wall of the preparation tower (10) through the outlet of the mixer (40) for supplying alkali solution to the preparation tower (10).

4. The sodium hydrosulfide preparation system according to claim 3, characterized in that, The primary alkali solution outlet (12) is communicated with the side wall of the stripping tower (20) through a first shunt pipe (121) and is communicated with the mixer (40) through a second shunt pipe (122), and a cooler (1221) is provided on the second shunt pipe (122).

5. The sodium hydrosulfide preparation system according to claim 4, wherein, A pH value detector (50) is provided on the second shunt pipe (122), an H2S detector (51) is provided at the exhaust port of the Nth stage of the N-stage clean gas unit, and an alkali solution flow control valve (52) is provided in the alkali solution source. The control system of the alkali solution flow control valve (52) is respectively connected with the pH value detector (50) and the H2S detector (51).

6. The sodium hydrosulfide preparation system according to claim 5, characterized in that, The alkali solution inlet group includes a first alkali solution first inlet (13) and a first alkali solution second inlet (14). The first alkali solution first inlet (13) and the first alkali solution second inlet (14) are arranged on the side wall of the preparation tower (10) from top to bottom. A first supply alkali valve (131) is provided on the first alkali solution first inlet (13), and a second supply alkali valve (141) is provided on the first alkali solution second inlet (14).

7. The sodium hydrosulfide preparation system according to claim 5, wherein, The first stage of the N-stage gas purification unit is a primary gas purification device (30): The primary gas purification device (30) is provided with a stirring tank (301). A second lye inlet (3011) is opened at the top of the stirring tank (301), and the stirring tank (301) is communicated with a lye source through the second lye inlet (3011); the primary purified gas inlet (31) is opened on the lower side wall of the stirring tank (301); a secondary purified gas outlet (3012) is opened at the top of the stirring tank (301), and is communicated with the second stage of the N-stage gas purification unit through the secondary purified gas outlet (3012); a secondary lye outlet (3013) is opened at the bottom of the stirring tank (301), and the stirring tank (301) is communicated with a mixer (40) through the secondary lye outlet (3013).

8. The sodium hydrosulfide preparation system according to claim 7, characterized in that, A distribution pipe (311) is connected inside the primary purified gas inlet (31). The distribution pipe (311) is annular and is arranged around the stirring shaft of the stirring tank (301). A number of air holes are evenly opened along the annular shape of the distribution pipe (311).

9. The sodium hydrosulfide preparation system according to claim 7, wherein, A temperature regulating sleeve (302) is sleeved outside the stirring tank (301). A temperature regulating cavity is preset inside the temperature regulating sleeve (302). The temperature regulating sleeve (302) is communicated with a second drain pipe (3022) and a third steam pipe (3021). A drain valve (30221) is provided on the second drain pipe (3022), and the third steam pipe (3021) is communicated with a steam source. A third steam valve (30211) is provided on the third steam pipe (3021).

10. The sodium hydrosulfide preparation system according to claim 9, wherein, The temperature regulating sleeve (302) is communicated with a circulating water inlet pipe (3023) and a circulating water outlet pipe (3024). An inlet valve (30231) is provided on the circulating water inlet pipe (3023), and an outlet valve (30241) is provided on the circulating water outlet pipe (3024).

11. The sodium hydrosulfide preparation system according to claim 7, characterized in that, The N-stage gas purification unit is a two-stage gas purification unit, and the second stage is a secondary gas purification device: The secondary gas purification device includes a reaction tube (60) arranged vertically. A third lye inlet (61) is opened at the top of the reaction tube (60), and the reaction tube (60) is communicated with a lye source through the third lye inlet (61); the secondary purified gas outlet (3012) is communicated with the upper part of the reaction tube (60); the bottom of the reaction tube (60) is connected with a gas-liquid separator (62). The H2S detector (51) is arranged at the exhaust port at the top of the gas-liquid separator (62). A tertiary lye outlet (621) is opened at the bottom of the gas-liquid separator (62), and the gas-liquid separator (62) is communicated with the mixer (40) through the tertiary lye outlet (621).

12. A method for preparing sodium hydrosulfide, characterized in that, Applicable to the sodium hydrosulfide preparation system described in any one of claims 5-11, including the following steps: React the acid gas with the first lye in a countercurrent manner to obtain a primary lye and a primary purified gas; Strip the primary lye with steam in a countercurrent manner to obtain a prefabricated liquid and an oil ammonia waste gas; Concentrate and cool the prefabricated liquid to obtain a sodium hydrosulfide product.

13. The preparation method of sodium hydrosulfide according to claim 12, characterized in that, The concentration is: reducing the water content in the prefabricated liquid by boiling evaporation.

14. The preparation method of sodium hydrosulfide according to claim 12, wherein It further includes the following steps: Divert the primary lye to obtain a first circulating lye; Cool the first recycled alkaline solution and then reflux it as the first part of the first alkaline solution to react countercurrently with the acidic gas.

15. The method for preparing sodium hydrosulfide according to claim 14, characterized in that, It further includes the following steps: Detect the pH value of the first recycled alkaline solution; Adjust the opening degree of the control valve and the reaction time of the countercurrent reaction between the acidic gas and the first alkaline solution according to the pH value of the first recycled alkaline solution.

16. The preparation method of sodium hydrosulfide according to claim 12, characterized in that, It further includes the following steps: Stir the primary purified gas countercurrently with the second alkaline solution to obtain a secondary purified gas and a second recycled alkaline solution; Reflux the second recycled alkaline solution as the second part of the first alkaline solution to react countercurrently with the acidic gas.

17. The method for preparing sodium hydrosulfide according to claim 16, wherein It further includes the following steps: React the secondary purified gas with the third alkaline solution in co-current and separate the gas and liquid to obtain a tertiary purified gas and a third recycled alkaline solution; Reflux the third recycled alkaline solution as the remaining part of the first alkaline solution to react countercurrently with the acidic gas.

18. The method for preparing sodium hydrosulfide according to claim 17, characterized in that, It further includes the following steps: Detect the content of H2S in the tertiary purified gas; Adjust the supply amounts of the second alkaline solution and the third alkaline solution according to the content of H2S in the tertiary purified gas.

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