A wet desulfurization process method and device with low by-product salt production

Abstract

The present application relates to coke oven gas desulfurization technical field, especially relates to a kind of low by-product salt generation's wet desulfurization process method and device, process method includes the following steps: precooling, desulfurization and regeneration step, wherein, by in precooling step, precooling tower uses "filtering screen plate+three filler layer+double spray pipe" structure, coal gas is filtered first through the dust impurities in coal gas of rotating filtering screen plate, then two-stage spray cooling is contacted with filler layer, so that coal gas temperature is accurately cooled to 25 DEG C, the design not only removes impurities, also creates suitable temperature condition for subsequent desulfurization, improves reaction efficiency, avoids the influence of dust impurities on precooling efficiency and desulfurization efficiency, so that coke oven gas wet desulfurization efficiency is greatly improved, reduces the interference of desulfurization reaction, reduces the invalid loss of catalyst, simultaneously, in desulfurization step, by adjusting the molar ratio of NH3 in ammonia water in desulfurization tower and H2S in tower, reaction is prompted to the direction conducive to the generation of ammonium sulfide.

Description

Technical Field

[0001] This invention relates to the field of coke oven gas desulfurization technology, and in particular to a wet desulfurization process and apparatus with low by-product salt production. Background Technology

[0002] As is well known, coke oven gas contains harmful impurities such as hydrogen sulfide, hydrogen cyanide, and organic sulfur compounds. Hydrogen sulfide is a highly toxic gas that strongly irritates the eyes and respiratory tract; inhalation of high concentrations can cause death. In humid environments, hydrogen sulfide can form sulfuric acid, accelerating the corrosion of equipment materials and shortening equipment lifespan. Hydrogen cyanide is also a highly toxic gas that can rapidly inhibit human respiratory enzymes, leading to intracellular asphyxiation and posing a threat to life. Hydrogen cyanide aqueous solutions can corrode equipment and generate iron salts in the system, causing pipe blockage. Organic sulfur compounds produce sulfur dioxide and other sulfides when burned, causing air pollution. When coke oven gas is used as a chemical raw material, the presence of organic sulfur compounds can also affect the purity and quality of the product. Therefore, coking plants typically install desulfurization devices to purify coke oven gas, ensuring that the hydrogen sulfide content is less than 0.02 g / m³, so that it will not cause harm to humans or pollution to the environment when used for industrial or domestic purposes.

[0003] Existing coke oven gas desulfurization processes are divided into dry desulfurization and wet desulfurization. Dry desulfurization uses solid desulfurization catalysts, while wet desulfurization uses liquid desulfurization catalysts. This application focuses on the wet desulfurization process. In the wet desulfurization process, the desulfurization liquid containing the catalyst sprayed from the top of the desulfurization tower comes into countercurrent contact with the gas, absorbing ammonia from the gas to form ammonia water. Simultaneously, under the catalytic action of the catalyst, it absorbs hydrogen sulfide, hydrogen cyanide, and organic sulfur from the gas. After the hydrogen sulfide content in the gas meets the required standard, it enters the ammonium sulfate section. The desulfurization liquid flows out from the bottom of the desulfurization tower and flows concurrently with the compressed air from the air compressor room, entering the regeneration tower together from the bottom for oxidation and regeneration. The regenerated solution flows back to the top of the desulfurization tower from the top of the tower via a level regulator, and is reused as desulfurization liquid. The elemental sulfur generated after regeneration forms sulfur foam, which floats at the top of the regeneration tower. The sulfur foam flows by gravity using the liquid level difference into the sulfur foam tank for further resource utilization.

[0004] However, in the existing wet desulfurization process, dust and impurities in the coal gas will enter the pre-cooling tower along with the coal gas. During the pre-cooling process, the dust and impurities will block the packing layer, which will greatly reduce the cooling efficiency of the pre-cooling tower and thus greatly reduce the efficiency of the entire desulfurization process.

[0005] Furthermore, in the critical stages of the desulfurization process, the ratio of the two reaction products, ammonium hydrosulfide and ammonium thiosulfate, remains uncontrollable and chaotic, becoming a core bottleneck restricting the efficient operation of the entire desulfurization system. This directly leads to a significant decline in sulfur recovery rate, high processing costs, and low economic benefits of sulfur recovery.

[0006] Therefore, there is an urgent need for a wet desulfurization process that can avoid the impact of dust impurities on the desulfurization efficiency of coal gas, improve the economic benefits of wet desulfurization, and reduce the processing cost of wet desulfurization. Summary of the Invention

[0007] To address the above problems, this invention provides a wet desulfurization process and apparatus with low by-product salt production. In the pre-cooling step, the pre-cooling tower adopts a structure of "filter plate + three packing layers + double spray pipes." The gas first passes through a rotating filter plate to filter dust and impurities, and then undergoes two stages of spray cooling to contact the packing layers, precisely cooling the gas temperature to 25°C. This design not only removes impurities but also creates suitable temperature conditions for subsequent desulfurization, improving reaction efficiency and avoiding the impact of dust and impurities on pre-cooling and desulfurization efficiency. This significantly improves the wet desulfurization efficiency of coke oven gas, reduces interference with the desulfurization reaction, and minimizes the ineffective loss of catalyst.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A wet desulfurization process with low by-product salt production includes the following steps:

[0010] Step a, pre-cooling: The gas is blown into the lower part of the pre-cooling tower by the blower. The gas comes into counter-current contact with the circulating coolant sprayed from the top of the pre-cooling tower, so that the gas temperature is cooled to 25°C.

[0011] Step b, desulfurization: The pre-cooled coal gas enters from the bottom of the desulfurization tower through a circulating pump and passes through the tower from bottom to top. The coal gas comes into counter-current contact with the desulfurization liquid containing catalyst sprayed down from the top of the desulfurization tower. The desulfurization liquid absorbs ammonia in the coal gas to form ammonia water. Under the catalytic action of the catalyst, it absorbs hydrogen sulfide, hydrogen cyanide and organic sulfur in the coal gas, so that the hydrogen sulfide content in the coal gas reaches ≤0.02g / m³. The coal gas that meets the standard is then transported to the ammonium sulfate section.

[0012] Step c, regeneration: The desulfurization liquid generated during the desulfurization process flows out from the bottom of the desulfurization tower and flows in parallel with the compressed air into the bottom of the regeneration tower. The desulfurization liquid is regenerated by oxidation. The regenerated desulfurization liquid flows into the desulfurization tower by gravity through the liquid level regulator to participate in the desulfurization reaction. The sulfur foam generated during the regeneration process floats on the top of the regeneration tower. The sulfur foam flows by gravity using the liquid level difference and enters the sulfur foam tank.

[0013] As an improvement, in step a, the pre-cooling includes the following steps:

[0014] Step a1: Input: Gas enters the precooling tower through the air inlet at the bottom of the precooling tower;

[0015] Step a2: Filtration. The gas is conveyed from bottom to top and comes into contact with the filter screen located above the gas inlet. The filter screen filters out dust and impurities in the gas.

[0016] Step a3: Primary spray cooling. The filtered coal gas passes through the first packing layer located above the filter screen. The first spray pipe above the first packing layer sprays coolant downwards. The coolant comes into counter-current contact with the coal gas at the first packing layer for cooling.

[0017] Step a4: Secondary spray cooling. After primary spray cooling, the coal gas is conveyed upward and passes through the second packing layer located above the first spray pipe. The second spray pipe located above the second packing layer sprays coolant downward and makes counter-current contact with the coal gas at the second packing layer for cooling.

[0018] Step a5, Output: After being cooled by secondary spraying, the gas is transported upwards. After passing through the third packing layer located above the second spray pipe, the gas is output through the gas outlet at the top of the precooling tower.

[0019] As an improvement, in step a2, the filter screen is horizontally rotated, and several sets of liquid collection tanks are arranged at equal intervals along the radial direction of the filter screen above the filter screen. The liquid collection tanks collect the cooled liquid, and the liquid collection tanks are intermittently rotated and tilted as the filter screen rotates horizontally, so that the coolant in the liquid collection tanks washes the filter screen below.

[0020] As an improvement, an inclined liquid collection guide plate is provided above the liquid collection tank. The liquid collection guide plate collects the coolant dripping from the first packing layer and guides the coolant into the liquid collection tank.

[0021] As an improvement, a lever is provided at the pivot of the liquid collection tank, and a stop bar is provided below the lever. The stop bar is located on the turntable, which is connected to the filter screen plate through a planetary gear transmission group. The turntable rotates in the opposite direction to the rotation of the filter screen plate. The stop bar comes into contact with the turntable as the turntable rotates, and the stop bar is moved, causing the liquid collection tank to rotate and tilt.

[0022] As an improvement, in step a2, the bottom of the precooling tower contains the cooled liquid, and the exterior of the precooling tower is provided with a circulating water tank that communicates with the bottom of the precooling tower. The circulating water tank is connected to the first spray pipe and the second spray pipe respectively through pipes.

[0023] As an improvement, an auxiliary filter screen is provided at the connection point between the circulating water tank and the precooling tower. This auxiliary filter screen filters the coolant flowing back into the circulating water tank.

[0024] As an improvement, in step a2, the bottom of the precooling tower is provided with a rotating blade that rotates synchronously with the filter screen. The rotating blade pushes the coolant at the bottom of the precooling tower to impact the auxiliary filter screen, and the rotating blade also propels the gas upward.

[0025] As an improvement, in step b, the equation for the desulfurization reaction is:

[0026] NH3 + H2O → NH3·H2O;

[0027] NH3·H2O + H2S → NH4HS + H2O;

[0028] 2NH3·H2O+H2S→(NH4)2S+2H2O;

[0029] NH3·H2O + HCN → NH4CN + H2O;

[0030] NH3·HO+NH4HS+(x-1)S+HPF→(NH4)2S X +H2O;

[0031] NH4CN+(NH4)2S X +HPF→NH4CNS+(NH4)2S (x-1) In the formula, x is an integer greater than 1.

[0032] As an improvement, the equation for the regeneration reaction in step c is:

[0033] NH4S + 1 / 2O2 + HPF → NH4OH + S;

[0034] (NH4)2S+1 / 2O2+H2O+HPF→2NH4OH+S;

[0035] (NH4)2Sx+1 / 2O2+H2O+HPF→2NH4OH+S;

[0036] NH4HS + 2O2 → (NH4)2S2O3 + H2O;

[0037] (NH4)2S2O3+O2→2(NH4)2SO4+S;

[0038] NH4CN+S→NH4SCN, where x is an integer greater than 1.

[0039] The beneficial effects of this invention are as follows:

[0040] (1) In the pre-cooling step, the present invention uses a pre-cooling tower to filter the dust impurities carried in the gas, thereby avoiding the influence of dust impurities on the pre-cooling efficiency and desulfurization efficiency, which greatly improves the wet desulfurization efficiency of coke oven gas, reduces the interference of desulfurization reaction, reduces the ineffective loss of desulfurization liquid, and the cooled liquid is recycled to improve resource utilization and reduce solid waste emissions.

[0041] (2) After removing dust, the contact between coal gas and desulfurization liquid is more direct, the desulfurization reaction efficiency is improved, the H2S content in the desulfurized coal gas can more stably meet the emission standards, reduce corrosion and air pollution in subsequent processes, and the sulfur foam is centrally treated during the regeneration process to avoid secondary pollution and improve resource utilization.

[0042] (3) In the pre-cooling step, the present invention uses a filter screen to filter dust impurities in the gas, and also uses a rotating filter screen combined with a liquid collection tank, a liquid collection guide plate and a gear transmission mechanism to automatically clean the filter screen by collecting coolant, thereby avoiding dust blockage, reducing the frequency of manual maintenance and improving the stability of continuous system operation.

[0043] In summary, this invention has the advantages of high desulfurization efficiency, low loss, high resource recovery rate, and stable operation, and is especially suitable for the field of wet desulfurization technology for coke oven gas. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the device connection in Embodiment 1 of the present invention;

[0045] Figure 2 This is a schematic diagram of the three-dimensional structure of the precooling tower in Embodiment 1 of the present invention;

[0046] Figure 3 This is a schematic diagram of the internal structure of the precooling tower in Embodiment 1 of the present invention;

[0047] Figure 4 This is a schematic diagram of the three-dimensional structure of the filter screen plate in Embodiment 1 of the present invention;

[0048] Figure 5 This is an enlarged schematic diagram of the filter screen structure in Embodiment 1 of the present invention;

[0049] Figure 6 This is a schematic diagram of the three-dimensional structure of the liquid collection tank in Embodiment 1 of the present invention;

[0050] Figure 7 This is a schematic diagram of the planetary gear transmission assembly structure in Embodiment 1 of the present invention;

[0051] Figure 8 This is a schematic diagram of the three-dimensional structure of the ball head seat in Embodiment 1 of the present invention;

[0052] Figure 9 This is an enlarged structural schematic diagram of the planetary gear transmission assembly according to Embodiment 1 of the present invention;

[0053] Figure 10 This is a schematic diagram of the bottom structure of the tower body in Embodiment 1 of the present invention;

[0054] Figure 11 This is a front view schematic diagram of the desulfurization tower in Embodiment 1 of the present invention;

[0055] Figure 12 This is a schematic cross-sectional view of the desulfurization tower in Embodiment 1 of the present invention;

[0056] Figure 13 This is a schematic diagram of the three-dimensional structure of the guide plate in Embodiment 1 of the present invention;

[0057] Figure 14 for Figure 13 Enlarged schematic diagram of the structure at point A in the middle;

[0058] Figure 15 This is a schematic diagram of the spray pipe installation structure in Embodiment 1 of the present invention;

[0059] Figure 16 This is a schematic diagram of the three-dimensional structure of the spray pipe in Embodiment 1 of the present invention;

[0060] Figure 17 This is a schematic diagram of the three-dimensional structure of the swirl plate in Embodiment 1 of the present invention;

[0061] Figure 18 for Figure 17 Enlarged schematic diagram of the structure at point B;

[0062] Figure 19 This is a schematic diagram of the three-dimensional structure of the auxiliary spray pipe in Embodiment 1 of the present invention;

[0063] Figure 20 for Figure 20 Enlarged schematic diagram of the structure at point C;

[0064] Figure 21 This is a schematic diagram of the three-dimensional structure of the corrugated plate in Embodiment 1 of the present invention;

[0065] Figure 22 for Figure 21 Enlarged schematic diagram of the structure at point D

[0066] Figure 23 This is a schematic diagram of the process method of Embodiment 2 of the present invention.

[0067] Figure reference numerals: Precooling tower 1, circulating water tank 10, circulating pump 101, auxiliary filter screen 102, coolant replenishment pipe 103, drain pipe 104, tower body 11, main air inlet 111, auxiliary air inlet 112, air outlet 113, coolant outlet 114, rotating blade 115, filter screen plate 12, rotating shaft 121, drive motor 122, ball head seat 123, mounting base 1231, ball head 1232, first packing layer 13, packing grid plate 131, packing 132, first spray pipe 14, second packing layer 15, second spray pipe 16, third packing layer 17, liquid collection tank 18, bearing seat 181, lever 182 Turntable 183, baffle 184, liquid guide plate 185, planetary gear transmission assembly 19, stellar gear 191, planetary gear 192, gear ring 193, hoisting base 194, desulfurization tower 2, desulfurization tower body 21, inlet flue 211, outlet flue 212, liquid discharge pipe 213, guide plate 22, guide vane 221, through shaft 222, guide channel 223, spray pipe 23, main pipe 231, branch pipe 232, spray nozzle 233, swirl plate 24, mounting plate 241, ball bearing 242, auxiliary spray pipe 25, flushing pipe 251, nozzle 252, corrugated plate 26, corrugated channel 261, regeneration tower 3, sulfur foam tank 4. Detailed Implementation

[0068] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0069] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0070] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0071] When this specification uses the prefixes "known to those skilled in the art," "prior art," or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those conventionally used in the art at the time the invention was proposed, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0072] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions (such as methods or systems) are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0073] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0074] Example 1:

[0075] like Figures 1-10 As shown, a wet desulfurization device with low by-product salt production includes, in sequence, a precooling tower 1, a desulfurization tower 2, a regeneration tower 3, and a sulfur foam tank 4, according to the gas processing order. The precooling tower 1 receives coke oven gas and performs spray cooling treatment. A cooling circulation module is connected to the precooling tower 1. Cooling water is sprayed downwards from the top of the precooling tower 1 and exchanges heat with the gas (which is coking gas), thereby cooling the gas. The coolant after heat exchange is discharged to the outside through the pipe at the bottom of the precooling tower 1. After cooling, it is circulated back to the top of the precooling tower 1 and discharged. The coolant after heat exchange still contains some ammonia water. This part of the ammonia water is separated by gas stripping and enters the ammonia water clarification tank. The gas stripping method uses steam or air to strip free ammonia gas (NH3) from the water and recovers ammonia through gas-liquid separation. Specifically, the ammonia-containing water is heated to 80-95℃ (to increase the volatility of ammonia), and then steam or air is introduced into the stripping tower, and the ammonia gas escapes from the water, achieving separation.

[0076] like Figures 11-22As shown, the desulfurization tower 2 and the precooling tower 1 are connected by pipes and valves. The desulfurization tower 2 receives the precooled gas, and the desulfurization liquid sprayed from top to bottom of the desulfurization tower 2 contacts the coke oven gas flowing from bottom to top, thus desulfurizing the coke oven gas. The specific structure of the desulfurization tower 2 includes a desulfurization tower body 21, an inlet flue 211 at the bottom of the desulfurization tower body 21 to receive the coke oven gas output from the precooling tower 1, an outlet flue 212 at the top of the desulfurization tower body 21, and a drain pipe 213 at the bottom of the desulfurization tower body 21 to discharge the desulfurization liquid. The desulfurization tower 21 is connected to the regeneration tower 3 via a pipeline. From bottom to top, the interior of the tower includes a guide plate 22, spray pipes 23, a swirl plate 24, auxiliary spray pipes 25, and a corrugated plate 26. The guide plate 22 is inclined and has a grid-like structure, consisting of arc-shaped guide vanes 221 and through-shafts 222 passing through the guide vanes 221. Guide channels 223 are formed between the guide vanes 221. Several sets of spray pipes 23 are stacked, each set including two parallel main pipes 231 and branch pipes extending horizontally outward from the main pipes 231. 232, branch-like spray nozzles 233 extend outward from the branch pipe 232. The main pipe 231 of the spray pipe 23 is connected to the external desulfurization liquid supply system and the regeneration tower 3. The swirl plate 24 is rotatably installed inside the desulfurization tower body 21. A fixed mounting plate 241 is provided below the swirl plate 24. Several balls 242 are evenly distributed on the mounting plate 241. The balls 242 provide rigid rolling support for the swirl plate 24, causing the swirl plate 24 to rotate with the flow of coke oven gas. It separates droplets by relying on the inertial force of the flue gas reversal. The auxiliary spray pipes 25 are arranged in layers, located in the wave... Above and below the corrugated plate 26, each layer of auxiliary spray pipes 25 is assembled in parallel from several auxiliary spray pipes 25. Each auxiliary spray pipe 25 includes a flushing pipe 251 and nozzles 252 arranged at equal intervals along the length of the flushing pipe 251. The corrugated plate 26 is arranged in a zigzag shape and is arranged in parallel. Adjacent corrugated plates 26 cooperate to form a corrugated channel 261. Through the flow guiding channel 223, the coke oven gas and desulfurization liquid are fully contacted. The corrugated channel 261 cooperates with the swirl plate 24 and separates the liquid droplets in the coke oven gas through the spraying of the auxiliary spray pipes 25.

[0077] It is worth noting that, in order to improve the contact efficiency between coke oven gas and desulfurization liquid, a packing layer can be set below the spray pipe 23 and above the guide plate 22 to increase the contact area between coke oven gas and desulfurization liquid and promote the contact efficiency between coke oven gas and desulfurization liquid.

[0078] The top and bottom of the regeneration tower 3 are connected to the desulfurization tower 2 via pipes and valves, respectively. The regeneration tower 3 receives the desulfurization liquid discharged from the desulfurization tower 2, and after oxidation regeneration, the regenerated desulfurization liquid is pumped back into the desulfurization tower 2. The structure of the desulfurization tower is also a conventional structure. For example, the invention patent with patent application number CN201510378551.6 specifically discloses a desulfurization regeneration tower. Therefore, the structure of the regeneration tower in this application will not be described in detail.

[0079] The sulfur foam tank 4 is connected to the regeneration tower 3. The sulfur foam tank 4 receives the sulfur foam discharged from the regeneration tower 3 and collects the sulfur particles in the sulfur foam. Specifically, the sulfur foam tank separates the sulfur particles in the sulfur-containing foam from the desulfurization liquid by gravity settling, bubble flotation or mechanical stirring, so as to achieve the enrichment and recovery of sulfur.

[0080] Here, we will focus on explaining the differences between the precooling tower 1 and the existing precooling tower. The precooling tower 1 of this application includes a tower body 11, and a filter screen plate 12, a first packing layer 13, a first spray pipe 14, a second packing layer 15, a second spray pipe 16, and a third packing layer 17 arranged sequentially from bottom to top along the tower body 11. The lower part of the tower body 11 is provided with a main air inlet 111 and an auxiliary air inlet 112. Both the main air inlet 111 and the auxiliary air inlet 112 are located below the filter screen plate 12. Coal gas enters the tower body 11 through the main air inlet 111 and the auxiliary air inlet 112. The top of the tower body 11 is provided with an air outlet 113. Coal gas is discharged from the tower body 11 through the air outlet 113. The bottom of the tower body 11 is provided with a coolant outlet 114. The cooled coolant is discharged from the coolant outlet 114.

[0081] To further explain, the filter screen plate 12 extends downward through the tower body 11 via a rotating shaft 121 (a rotating sealing ring is provided at the point where the rotating shaft 121 and the tower body 11 extend), and is connected to the drive motor 122 installed below the tower body 11 via a coupling. The drive motor 122 drives the filter screen plate 12 to rotate. Inside the tower body 11, at the lower edge of the filter screen plate 12, a ball head seat 123 is installed to support the rotation of the filter screen plate 12. The ball head seats 123 are arranged equidistantly in a circle, and the ball head seat 123 includes a mounting base 1231 and a rolling ball head 1232.

[0082] Furthermore, several sets of liquid collection tanks 18 are provided above the filter screen plate 12. These liquid collection tanks 18 are all arranged radially along the filter screen plate 12 and are equidistantly arranged around the rotating shaft 121. Preferably, there are eight sets of liquid collection tanks 18. Each liquid collection tank 18 is a hollow semi-circular tube. Both ends of the liquid collection tank 18 are rotatably mounted on the filter screen plate 12 via bearing seats 181. A lever 182 is provided at the end of the liquid collection tank 18 near the rotating shaft 121, and the lever 182 serves as the liquid collection tank 18. The counterweight block, through the counterweight of the lever 182, ensures that the opening of the liquid collection tank 18 always faces upward. Below the lever 182, there is a set of turntables 183, and a stop bar 184 is set on the turntable 183. The stop bar 184 is set one-to-one with the lever 182. The stop bar 184 is set in an n-shape. As the turntable 183 rotates, the stop bar 184 abuts against the lever 182. As the stop bar 184 moves the lever 182, the liquid collection tank 18 rotates, thereby allowing the coolant in the liquid collection tank 18 to be poured out.

[0083] The rotation of turntable 183 is driven by the rotation of filter screen plate 12 through planetary gear transmission assembly 19. As filter screen plate 12 rotates, turntable 183 rotates in the opposite direction, and the rotational speed of turntable 183 is less than that of filter screen plate 12. Planetary gear transmission assembly 19 consists of sun gear 191, planetary gears 192 and gear ring 193. Sun gear 191 is sleeved on rotating shaft 121, and planetary gears 192 are arranged equidistantly around the circumference of sun gear 191. There are three sets of planetary gears 192, and the planetary gears 192 are connected by a lifting base. 194 is fixedly connected to the packing grid plate 131 at the bottom of the first packing layer 13. The planetary gear 192 is only set to rotate on its own axis. The gear ring 193 is sleeved on the outside of the planetary gear 192. As the sun gear 191 rotates, the gear ring 193 is driven to rotate in the opposite direction through the transmission of the planetary gear 192. The gear ring 193 is connected to the turntable 183. The turntable 183 rotates with the gear ring 193. One end bearing seat 181 of the liquid collection tank 18 is installed on the inner wall of the tower body 11, and the other end bearing seat 181 of the liquid collection tank 18 is installed on the lifting base 194.

[0084] In addition, a liquid guide plate 185 is inclinedly arranged above the liquid collection tank 18. The two ends of the liquid guide plate 185 are respectively fixedly installed on the corresponding bearing seats 181. The liquid guide plate 185 collects the coolant dripping from the first packing layer 13 into the corresponding liquid collection tank 18.

[0085] It should be noted that the rotational angular velocity of the turntable 183 is much smaller than that of the rotating shaft 121. Therefore, when the filter screen plate 12 rotates, the stop bar 184 and the lever 182 on the turntable 183 contact each other to cause the liquid collection tank 18 to tilt. Each tilting position is different relative to the filter screen plate 12, thus enabling the tilting of the liquid collection tank 18 to cover the entire area of ​​the filter screen plate 12.

[0086] Furthermore, the first packing layer 13, the second packing layer 15, and the third packing layer 17 have the same structure, all including a packing grid 131 and packing material 132 located on the packing grid 131. The first spray pipe 14 and the second spray pipe 16 are respectively connected to the circulating water tank 10 outside the tower body 11. A circulating pump 101 is installed on the circulating water tank 10, which guides the coolant into the first spray pipe 14 and the second spray pipe 16. The circulating water tank 10 is connected to the coolant discharge port 114 at the bottom of the cooling tower 11. Furthermore, an auxiliary filter screen 102 is installed on the circulating water tank 10 at the coolant outlet 114 to filter the circulating coolant. A coolant replenishment pipe 103 and a drain pipe 104 are also installed on the circulating water tank 10. It is worth emphasizing that a rotating blade 115 is installed inside the tower body 11. The rotating blade 115 is mounted on the rotating shaft 121. As the rotating shaft 121 rotates, the rotating blade 115 agitates the coolant at the bottom of the tower body 11. At the same time, the rotating blade 115 blows the gas entering from the top upward.

[0087] Example 2:

[0088] like Figure 23 As shown, a wet desulfurization process with low by-product salt generation includes the following steps:

[0089] Step a, pre-cooling: The gas is blown into the lower part of the pre-cooling tower 1 by the blower. The gas comes into counter-current contact with the circulating coolant sprayed from the top of the pre-cooling tower 1, so that the gas temperature is cooled to 25°C.

[0090] Step b, desulfurization: The pre-cooled coal gas enters from the bottom of desulfurization tower 2 through a circulating pump and passes through the desulfurization tower 2 from bottom to top. The coal gas comes into counter-current contact with the desulfurization liquid containing catalyst sprayed down from the top of the desulfurization tower 2. The desulfurization liquid absorbs ammonia in the coal gas to form ammonia water. Under the catalytic action of the catalyst, it absorbs hydrogen sulfide, hydrogen cyanide and organic sulfur in the coal gas, so that the hydrogen sulfide content in the coal gas reaches ≤0.02g / m³. The coal gas that meets the standard is then transported into the ammonium sulfate section.

[0091] Step c, regeneration: The desulfurization liquid generated during the desulfurization process flows out from the bottom of the desulfurization tower 2 and flows in parallel with the compressed air into the bottom of the regeneration tower 3. Through oxidation regeneration, the regenerated desulfurization liquid flows into the desulfurization tower by gravity through the liquid level regulator to participate in the desulfurization reaction. The sulfur foam generated during the regeneration process floats on the top of the regeneration tower 3. The sulfur foam flows by gravity using the liquid level difference and enters the sulfur foam tank 4.

[0092] In step a, the pre-cooling includes the following steps:

[0093] Step a1: Input: Gas enters the precooling tower 1 through the main air inlet 111 and the auxiliary air inlet 112 at the bottom of the precooling tower 1.

[0094] Step a2: Filtration. The gas is conveyed from bottom to top and comes into contact with the filter screen 12 located above the main air inlet 111 and the auxiliary air inlet 112. The filter screen 12 filters out dust and impurities in the gas.

[0095] Step a3: First spray cooling. The filtered coal gas passes through the first packing layer 13 located above the filter screen plate 12. The first spray pipe 14 above the first packing layer 13 sprays coolant downwards. The coolant and the coal gas come into counter-current contact at the first packing layer 13 for cooling.

[0096] Step a4: Secondary spray cooling. After primary spray cooling, the coal gas is conveyed upward and passes through the second packing layer 15 located above the first spray pipe 14. The second spray pipe 16 located above the second packing layer 15 sprays coolant downward and makes counter-current contact with the coal gas at the second packing layer 15 for cooling.

[0097] Step a5, Output: After being cooled by secondary spraying, the gas is transported upwards. After passing through the third packing layer 17 located above the second spray pipe 16, the gas is output through the gas outlet 113 at the top of the precooling tower.

[0098] In step a2, the dust and impurities filtered by the filter screen 12 adhere to the filter screen 12. The collected coolant in the collection tank on the filter screen 12 is poured out to flush the filter screen 12, causing the dust and impurities adhering to the filter screen 12 to be washed off. Due to the concentrated pouring of the coolant, the flushing force offsets the gas pressure exerted on the filter screen 12 by the gas, allowing the dust and impurities to be smoothly flushed away by the coolant. This prevents the filter screen 12 from being clogged by dust and impurities, achieving automatic cleaning of the filter screen, avoiding dust blockage, reducing the frequency of manual maintenance, and improving the continuous operation stability of the system.

[0099] Furthermore, in step a2, the bottom of the precooling tower 1 contains cooled liquid, and the exterior of the precooling tower 1 is provided with a circulating water tank 10 that communicates with the bottom of the precooling tower 1. The circulating water tank 10 is connected to the first spray pipe 14 and the second spray pipe 16 through pipes, and the coolant in the circulating water tank 10 is circulated by the circulating pump 101.

[0100] Furthermore, in step a2, the bottom of the precooling tower 1 is provided with a rotating blade 115 that rotates synchronously with the filter screen 12. The rotating blade 115 rotates and pushes the coolant at the bottom of the precooling tower 1 to impact the auxiliary filter screen 102, and the rotating blade 115 rotates and blows the gas upward.

[0101] Furthermore, the catalyst in the desulfurization liquid of this invention is an HPF catalyst. The HPF catalyst is a composite catalyst composed of hydroquinone, a dinuclear cobalt phthalocyanine sulfonation catalyst, and ferrous sulfate. Therefore, in step b, the equation for the desulfurization reaction is:

[0102] NH3 + H2O → NH3·H2O;

[0103] NH3·H2O + H2S → NH4HS + H2O;

[0104] 2NH3·H2O+H2S→(NH4)2S +2H2O;

[0105] NH3·H2O + HCN → NH4CN + H2O;

[0106] NH3·HO+ NH4HS+(x-1)S+HPF→(NH4)2S X +H2O;

[0107] NH4CN+(NH4)2S X + HPF→NH4CNS+(NH4)2S (x-1) In the formula, x is an integer greater than 1.

[0108] Accordingly, in step c, the equation for the oxidative regeneration reaction of the desulfurization liquid is:

[0109] NH4S + 1 / 2O2 + HPF → NH4OH + S;

[0110] (NH4)2S+1 / 2O2+H2O+HPF→2NH4OH+S;

[0111] (NH4)2Sx+1 / 2O2+H2O+HPF→2NH4OH+S;

[0112] NH4HS+2O2→(NH4)2S2O3+ H2O;

[0113] (NH4)2S2O3+O2→2(NH4)2SO4+S;

[0114] NH4CN+S→NH4SCN, where x is an integer greater than 1.

[0115] Furthermore, to ensure sufficient reaction between NH3 and H2S in the ammonia water during desulfurization, thereby reducing the content of ammonium thiosulfate and increasing the content of ammonium thiocyanate, this invention also adjusts the molar ratio of NH3 to H2S in the ammonia water within the desulfurization tower to be greater than 2:1. This promotes the reaction in a direction favorable to the formation of ammonium sulfide. Specifically, during the desulfurization step, the H2S content within the desulfurization tower is monitored in real-time, and the change in H2S content is preset (for example, the preset control range for the change in H2S content is x%, where x can be any value between 3 and 6, such as 3%, 4%, 5%, 6%, or 3.5%). (4.5%, 5.5%, etc., any variation in H2S content within the control and adjustment range of this invention falls within the protection scope of this invention.) When the variation in H2S content in the desulfurization tower exceeds the preset value, the NH3 content in the ammonia water in the desulfurization tower can be supplemented to ensure that the molar ratio of NH3 to H2S is always greater than 2:1. This allows the reaction products during the desulfurization process to be regulated, generating as much ammonium sulfide as possible, increasing the yield of elemental sulfur after the decomposition of ammonium sulfide, improving the sulfur recovery rate, reducing the generation of ammonium hydrosulfide, reducing the generation of low-value by-product ammonium thiosulfate during regeneration, improving economic benefits, reducing the ammonia loss rate of the system, reducing losses, saving costs, and improving the stability of the system.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wet flue gas desulfurization process method with low by-product salt production, characterized by, It comprises the following steps: Step a, pre-cooling, the gas is blown into the lower part of the pre-cooling tower by the air blowing device, and the gas is in countercurrent contact with the circulating cooling liquid sprayed from the top of the pre-cooling tower from the lower part of the pre-cooling tower to cool the gas temperature to 25℃; In the step a, the pre-cooling comprises the following steps: Step a1, input, the gas enters the inside of the pre-cooling tower through the gas inlet in the lower part of the pre-cooling tower; Step a2, filtration, the gas is in contact with the filter screen above the gas inlet from bottom to top, and the filter screen filters the dust impurities in the gas; Step a3, primary spray cooling, the filtered gas passes through the first filler layer above the filter screen, and the first spray pipe above the first filler layer sprays the cooling liquid downward, and the cooling liquid and the gas are in countercurrent contact at the first filler layer for cooling; Step a4, secondary spray cooling, the gas after the primary spray cooling is conveyed upwardly, passes through the second filler layer above the first spray pipe, and the second spray pipe above the second filler layer sprays the cooling liquid downward, and the cooling liquid and the gas are in countercurrent contact at the second filler layer for cooling; Step a5, output, the gas after the secondary spray cooling is conveyed upwardly, and the gas passes through the third filler layer above the second spray pipe and is output through the gas outlet at the top of the pre-cooling tower; In the step a2, the filter screen is horizontally rotatably arranged, a plurality of groups of liquid collecting troughs are arranged above the filter screen and are equidistantly spaced along the radial direction of the filter screen, both ends of the liquid collecting trough are rotatably mounted on the filter screen through bearing seats, the liquid collecting trough collects the cooled cooling liquid, and the liquid collecting trough is intermittently rotated and poured with the horizontal rotation of the filter screen, and the cooling liquid in the liquid collecting trough flushes the filter screen below; A push rod is arranged at the rotating shaft of the liquid collecting trough, a stop rod is arranged below the push rod, the stop rod is arranged on a rotating disc, the rotating disc is drivingly connected with the filter screen through a planetary gear transmission group, and the rotating disc rotates reversely with the rotation of the filter screen, the stop rod rotates with the rotating disc, and the stop rod is in contact with the stop rod to push the stop rod to rotate and pour the liquid collecting trough; Step b, desulfurization, the pre-cooled gas enters from the bottom of the desulfurization tower through the circulating pump, passes through the desulfurization tower from bottom to top, and is in countercurrent contact with the desulfurization liquid containing catalyst sprayed from the top of the desulfurization tower, the desulfurization liquid absorbs the ammonia in the gas to form ammonia water, and under the catalysis of the catalyst, absorbs the hydrogen sulfide, hydrogen cyanide and organic sulfur in the gas, so that the content of hydrogen sulfide in the gas reaches ≤0.02g / m³, and the qualified gas is conveyed into the ammonium sulfate section; Step c, regeneration, the desulfurization liquid generated in the desulfurization process flows out from the bottom of the desulfurization tower, flows with the compressed air, enters the bottom of the regeneration tower, and is regenerated by oxidation, and the regenerated desulfurization liquid flows into the desulfurization tower through the liquid level regulator to participate in the desulfurization reaction, and the sulfur foam generated in the regeneration process floats on the top of the regeneration tower, and the sulfur foam flows into the sulfur foam tank by the liquid level difference.

2. The low by-product salt generation wet desulfurization process method according to claim 1 is characterized in that: An inclined liquid collection guide plate is provided above the liquid collection tank. The liquid collection guide plate collects the coolant dripping from the first packing layer and guides the coolant into the liquid collection tank.

3. The wet desulfurization process with low by-product salt generation according to claim 1, characterized in that: In step a2, the bottom of the precooling tower contains cooled liquid, and the outside of the precooling tower is provided with a circulating water tank that communicates with the bottom of the precooling tower. The circulating water tank is connected to the first spray pipe and the second spray pipe through pipes respectively.

4. The wet desulfurization process with low by-product salt generation according to claim 3, characterized in that: An auxiliary filter screen is installed at the connection point between the circulating water tank and the precooling tower. This auxiliary filter screen filters the coolant that flows back into the circulating water tank.

5. The wet desulfurization process with low by-product salt generation according to claim 4, characterized in that: In step a2, the bottom of the precooling tower is provided with a rotating blade that rotates synchronously with the filter screen. The rotating blade pushes the coolant at the bottom of the precooling tower to impact the auxiliary filter screen, and the rotating blade also propels the gas upward.

6. The wet desulfurization process with low by-product salt generation according to claim 1, characterized in that: In step b, the equation for the desulfurization reaction is: NH3 + H2O → NH3·H2O; NH3·H2O + H2S → NH4HS + H2O; 2NH3·H2O+H2S→(NH4)2S +2H2O; NH3·H2O + HCN → NH4CN + H2O; NH3- HO + NH4HS + (x-1) S + HPF -> (NH4)2S X + H2O; NH4CN + (NH4)2S X + HPF→ NH4CNS + (NH4)2S (x-1) wherein x is an integer greater than 1.

7. The wet desulfurization process with low by-product salt generation according to claim 1, characterized in that: In step c, the equation for the regeneration reaction is: NH4S + 1 / 2O2 + HPF → NH4OH + S; (NH4)2S+1 / 2O2+H2O+HPF→2NH4OH+S; (NH4)2Sx+1 / 2O2+H2O+HPF→2NH4OH+S; NH4HS+2O2→(NH4)2S2O3+ H2O; (NH4)2S2O3+O2→2(NH4)2SO4+S; NH4CN+S→NH4SCN, where x is an integer greater than 1.

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