Purification system and purification method for high-chlorine and high-sulfur flue gas

Abstract

The invention provides a purification system and a purification method for high-chlorine and high-sulfur flue gas, and belongs to the technical field of waste gas treatment. The purification system comprises an alkali liquor absorption unit, a clear water immersion cleaning unit and a deep dechlorination unit, the alkali liquor absorption unit comprises a washing liquid tank, a washing cylinder and a gas outlet pipe which are vertically arranged above the washing liquid tank, a gas inlet pipe connected with the top end of the washing cylinder, a liquid inlet pipe connected with the middle lower end of the washing cylinder, and a spray head arranged in the washing cylinder and communicated with the liquid inlet pipe; the spray head comprises a venturi nozzle and a flow guide disc with a built-in flow guide channel which are connected in sequence; a passive rotating element is arranged at the tail end of the washing drum; a gas-liquid separation disc is arranged at the tail end of the gas outlet pipe; the deep dechlorination unit comprises a deep dechlorination tank filled with a colloidal solution, an adsorption fixed bed and an air blowing element. According to the invention, the reverse washing alkali liquor absorption unit, the clear water immersion cleaning unit and the deep dechlorination unit are arranged, so that chloride ions and sulfur trioxide in the flue gas are efficiently removed.

Description

Technical Field

[0001] The invention belongs to the technical field of waste gas treatment, and in particular relates to a purification system and a purification method for high-chlorine and high-sulfur flue gas. Background Art

[0002] Smoke ash is the main waste gas in the metallurgical industry. Its main components are solid particles and part of the flue gas. The commonly used smoke ash treatment method is bag dust removal. Since the flue gas contains a certain amount of chloride ions and sulfur trioxide (sulfuric anhydride), during the flue gas bag dust removal process, the dew point of sulfur trioxide is increased after the quenching tower sprays water to cool it down. Combined with the presence of chloride ions, equipment corrosion is significantly aggravated. When the chloride ions in the bag smoke exceed 10%, the pressure difference of the bag increases significantly. If the influence of sulfur trioxide and chloride ions is ignored, the resistance fluctuation of the bag dust collector is very large. In severe cases, it directly causes the bag to be scrapped, resulting in production suspension.

[0003] Therefore, the current research direction is to add a preliminary purification method at the front end of the bag dust removal process to remove chloride ions and sulfur trioxide to reduce their adverse effects on the subsequent bag dust removal process. The specific method is: add liquid alkali to the quench tower spray system, and mix the alkali solution and the quench tower water solution in proportion to spray into the quench tower system to initially intercept the chloride ions and sulfur trioxide (sulfuric anhydride) in the quench tower process to react and eliminate the impact on the subsequent bag dust collection.

[0004] The above method has the following defects: (1) The removal efficiency is limited. The reason is that the soot produced by metallurgy generally comes from high-temperature smelting furnaces. Its temperature is relatively high and it will rise rapidly when discharged. In the spray system, its contact time and area with the absorption liquid (such as liquid alkali, etc.) are limited, resulting in a small amount of chloride ions and sulfides being absorbed, especially the chloride ion degradation efficiency is very low; (2) It is easy to be blocked. Since the soot contains a large amount of solid particles, it is easy to cause blockage of the system pipeline in the quenching tower spray system. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a purification system and purification method for high-chlorine and high-sulfur flue gas, aiming to solve at least one technical problem in the background technology.

[0006] The present invention is achieved in that:

[0007] A first aspect of the present invention provides a purification system for high-chlorine and high-sulfur flue gas, the purification system comprising:

[0008] The alkali solution absorption unit is used for countercurrent contact between the flue gas and the alkali solution, and the alkali solution washes the flue gas to initially remove the chlorine and sulfur pollutants therein;

[0009] The clean water immersion unit is used to clean the airflow after being treated by the alkali solution absorption unit to prevent the alkali solution in the airflow from entering the subsequent units;

[0010] Deep dechlorination unit, used to deeply remove residual chloride ions;

[0011] The alkali liquid absorption unit includes a washing liquid tank, a washing cylinder vertically arranged above the washing liquid tank and a gas outlet pipe, an air inlet pipe connected to the top of the washing cylinder, a liquid inlet pipe connected to the middle and lower end of the washing cylinder, and a nozzle arranged inside the washing cylinder and connected to the liquid inlet pipe; the air inlet pipe allows the flue gas to enter the washing cylinder from top to bottom, and the nozzle sprays the alkali liquid into the flue gas flow from bottom to top in reverse, and the gas-liquid turbulent contact realizes the washing of the flue gas by the alkali liquid; the nozzle includes a Venturi nozzle connected in sequence and a guide plate with a built-in guide channel; a passive rotating element is arranged at the end of the washing cylinder; a gas-liquid separation plate is arranged at the end of the gas outlet pipe;

[0012] The clean water immersion unit includes a cleaning tank containing clean water and an injection element for introducing air flow into the clean water;

[0013] The deep dechlorination unit comprises a deep dechlorination tank with a colloidal solution inside, an adsorption fixed bed inside the upper part of the deep dechlorination tank, and an aeration element for introducing airflow into the colloidal solution.

[0014] Furthermore, the guide plate includes a plate body and guide channels arranged on the plate body. The guide channels are inclined and through-arranged, and the number of the guide channels is at least 2 groups.

[0015] Furthermore, the number of the guide channels is 2 to 4 groups, and the outlets are evenly distributed.

[0016] Furthermore, a spirally distributed guide rib is arranged on the middle inner wall of the guide channel; the number of spiral turns of the guide rib is 3 to 5.

[0017] Furthermore, the passive rotating element comprises a horizontal rotating shaft and at least three sets of blades fixed on the outer wall of the rotating shaft, and the driving force for the rotation of the passive rotating element is a gas-liquid mixture flowing from top to bottom in the washing tub.

[0018] Furthermore, the gas-liquid separation disc is a filter screen, and the middle part is a cone extending downward.

[0019] Furthermore, an air distribution plate with a porous structure is arranged inside the washing tub and below the air inlet pipe.

[0020] The second aspect of the present invention provides a method for purifying high-chlorine and high-sulfur flue gas, using the above-mentioned purification system; the purification method comprises the following steps:

[0021] The high-chlorine and high-sulfur flue gas is introduced into the alkali solution absorption unit after being accelerated by the fan. After being accelerated by the fan, the flue gas enters the washing drum from top to bottom, and collides with the alkali solution spraying from bottom to top in the opposite direction, so that the alkali solution washes the flue gas in the washing drum;

[0022] The liquid after washing falls into the washing liquid tank, and the gas enters the clean water immersion unit through the gas outlet pipe to remove the residual alkali liquid in the gas;

[0023] The gas treated by the clean water washing unit enters the deep dechlorination unit, where the colloidal solution is first condensed under the action of chloride ions in the gas, and then the residual pollutants in the gas are adsorbed by the adsorption fixed bed.

[0024] Furthermore, the flow rate of the flue gas entering the washing drum is 3m / s to 5m / s; the flow rate of the alkali solution entering the washing drum is 0.25m / s to 0.5m / s.

[0025] Furthermore, the colloidal solution is a plant protein solution; and the filler of the adsorption fixed bed is a molecular sieve or activated carbon.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention is provided with a reverse washing alkali solution absorption unit, a clean water immersion unit and a deep dechlorination unit to efficiently remove chloride ions and sulfur trioxide in the flue gas.

[0028] 2. The alkali solution absorption unit of the present invention realizes high-speed reverse collision of gas-liquid two phases to form a highly turbulent gas phase mixing zone. The gas-liquid two phases appear in the form of foam or mist and are in high-speed turbulent contact. In this process, the contact surface area is large and constantly moves and renews, thereby achieving an efficient washing effect.

[0029] 3. The present invention utilizes the colloidal properties of the plant protein solution and the property of chlorine as an electrolyte to efficiently remove chlorine from the flue gas; combined with an adsorption fixed bed, deep purification of the flue gas is achieved.

[0030] 4. The present invention is provided with a guide channel, a guide plate, and a guide rib to obtain a larger angle of the liquid spray area and a higher liquid spray speed, thereby enhancing the washing effect of the alkali solution on the flue gas.

[0031] 5. The present invention provides a passive rotating element to increase the gas-liquid two-phase turbulent contact time, thereby achieving washing efficiency enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the purification system of the present invention;

[0033] Figure 2 It is a schematic diagram of the overall and partial structures of the nozzle in the purification system of the present invention;

[0034] Figure 3 It is a side view structural schematic diagram of a passive rotating element in the purification system of the present invention;

[0035] Figure 4 It is a schematic diagram of the top view of the gas-liquid separation disk in the purification system of the present invention.

[0036] Illustration: 101-washing liquid tank; 102-passive rotating element, 103-liquid inlet pipe, 104-spray nozzle, 105-washing cylinder, 106-air inlet pipe, 107-gas outlet pipe, 108-gas-liquid separation plate, 109-gas separation plate, 110-guide plate, 111-Venturi nozzle, 112-plate body, 113-guide channel, 114-guide rib;

[0037] 201-cleaning tank, 202-jet element;

[0038] 301-deep dechlorination tank, 302-adsorption fixed bed, 303-aeration element. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] like Figure 1 As shown, a purification system for high-chlorine and high-sulfur flue gas, the purification system comprises:

[0041] The alkali solution absorption unit is used for countercurrent contact between the flue gas and the alkali solution, and the alkali solution washes the flue gas to initially remove the chlorine and sulfur pollutants therein;

[0042] The clean water immersion unit is used to clean the airflow after being treated by the alkali solution absorption unit to prevent the alkali solution in the airflow from entering the subsequent units;

[0043] Deep dechlorination unit, used to deeply remove residual chloride ions;

[0044] The alkali solution absorption unit, the clean water immersion unit, and the deep dechlorination unit are connected by pipelines, and also include matching valves, pump bodies, measuring instruments, etc. Their structure, composition, and connection adopt conventional settings, which are not marked in the figure and are not elaborated in detail by the present invention.

[0045] Among them, the alkali solution absorption unit includes a washing liquid tank 101, a washing cylinder 105 and a gas outlet pipe 107 vertically arranged above the washing liquid tank 101, an air inlet pipe 106 connected to the top of the washing cylinder 105, a liquid inlet pipe 103 connected to the middle and lower ends of the washing cylinder 105, and a nozzle 104 arranged inside the washing cylinder 105 and connected to the liquid inlet pipe 103; after being accelerated by the fan, the flue gas enters the washing cylinder 105 from top to bottom through the air inlet pipe 106, and the nozzle 104 sprays the alkali solution from bottom to top into the airflow of the flue gas, and the gas-liquid turbulent contact realizes the washing of the flue gas by the alkali solution.

[0046] In the washing drum 105, the gas-liquid two phases collide in the opposite direction at high speed. When the momentum of the two phases reaches equilibrium, a highly turbulent gas phase mixing zone is formed. The gas-liquid two phases appear in the form of foam or mist and are in high-speed turbulent contact. In this process, the contact surface area is large and constantly moves and renews, thereby achieving an efficient washing effect. The height of the washing drum 105 is generally not less than 1000mm, between 1000mm and 1600mm; the inner diameter is generally not less than 100mm, between 100mm and 150mm, and can be adjusted according to actual needs.

[0047] Since the gas-liquid two-phase countercurrent contact, the liquid phase moves from bottom to top, and its momentum has a greater impact on the washing effect. Therefore, the present invention improves the nozzle 104, which includes a venturi nozzle 111 and a guide plate 110 with a built-in guide channel 113 connected in sequence, such as Figure 2 As shown, Figure 2 (a) is a main view of the nozzle 104, (b) is a top view of the guide plate 110, and (c) is a cross-sectional view of (b) along the AA direction; the Venturi nozzle 111 is connected to the liquid inlet pipe 103. The Venturi nozzle is designed based on the Bernoulli principle of gravity and reasonable geometric surface parameters. It can form a large flow circulation. When the high-speed liquid passes through the Venturi nozzle, it drives the surrounding liquid into the injection to form a circulation.

[0048] The guide plate 110 includes a plate body 112 and a guide channel 113 arranged on the plate body 112. The guide channel 113 is inclined and through-arranged, and the number of the guide channel 113 is at least 2 groups (preferably 2 to 4 groups) and the outlets are evenly distributed; the function of the guide plate 110 is to obtain a larger angle of the spray area and a higher spray speed; the middle inner wall of the guide channel 113 is provided with spirally distributed guide ribs 114, and the number of spiral turns of the guide ribs 114 is 3 to 5 turns. The function of the guide ribs 114 is to guide the spray to rotate, thereby further enhancing the function of the guide plate 110.

[0049] In the washing drum 105, although the gas-liquid two phases form high-speed turbulent contact in the gas-liquid mixing zone under the action of the jet, the alkali liquid will fall freely under the action of gravity and vertically enter the washing liquid tank 101 under the action of downstream. In order to further improve the washing effect, a passive rotating element 102 is set at the end of the washing drum 105; Figure 3 As shown, the passive rotating element 102 includes a horizontal rotating shaft and at least three groups of blades fixed on the outer wall of the rotating shaft. The power for the rotation of the passive rotating element 102 is the gas-liquid mixture flowing downstream from top to bottom in the washing drum 105. As the alkaline liquid flows downstream, the passive rotating element 102 temporarily slows down its falling speed, and as it rotates, the gas-liquid two phases are brought into turbulent contact again, thereby achieving washing efficiency enhancement.

[0050] After washing in the washing barrel 105, the gas and liquid phases enter the washing liquid tank 101, where the liquid settles under the action of gravity, and the gas is discharged through the gas outlet pipe 107. Since the flue gas is a high-temperature exhaust gas, although the temperature is reduced after washing, it still maintains a high temperature, so the gas flowing to the gas outlet pipe 107 contains more alkali liquid, and its form tends to be gas mist, so a gas-liquid separation plate 108 is set at the end of the gas outlet pipe 107. Figure 4 As shown; the gas-liquid separation disk 108 is a filter screen, and the middle part is a cone extending downward. Through mechanical collision, due to the different densities and movement speeds of gas and liquid, part of the liquid will settle and fall after being blocked by the gas-liquid separation disk 108.

[0051] After being accelerated by the fan, the flue gas passes vertically downward into the washing barrel 105 through the air vent at the top, and is concentrated below the air inlet pipe 106, resulting in uneven gas distribution. The present invention arranges a porous gas distributor 109 inside the washing barrel 105 and below the air inlet pipe 106. The gas distributor 109 is provided with evenly distributed through holes, so that the flue gas introduced from the top is evenly dispersed when passing through the gas distributor 109. After passing through the small holes, it continues to downward and contacts and mixes with the alkaline solution sprayed from the nozzle 104, which is conducive to a more uniform spray of the flue gas in the washing barrel 105.

[0052] The clean water immersion unit comprises a cleaning tank 201 containing clean water and an injection element 202 for introducing air flow into the clean water.

[0053] The deep dechlorination unit comprises a deep dechlorination tank 301 with a colloidal solution inside, an adsorption fixed bed 302 inside the upper part of the deep dechlorination tank 301, and an aeration element 303 for introducing airflow into the colloidal solution. The colloidal solution is a plant protein solution; the filler of the adsorption fixed bed 302 is a molecular sieve or activated carbon.

[0054] The main forms of chlorine in flue gas are chloride ions, chlorides, chlorates and organic chlorine. During the high-temperature smelting process, organic chlorine substances may generate inorganic compounds such as chloride ions, chlorides and chlorates by sublimation and evaporation. At the same time, the incineration process may trigger a chemical reaction between chlorides and organic matter to generate new organic chlorine substances. The plant protein solution has colloidal properties, and the chlorine element in the flue gas can act as an electrolyte, causing the plant protein solution to condense, thereby removing the chlorine element in the flue gas; the adsorption fixed bed 302 is to adsorb residual gaseous pollutants, such as sulfides and carbon dioxide that are not completely absorbed by the alkali solution absorption unit.

[0055] In a specific implementation, the above purification system is used to purify high-chlorine and high-sulfur flue gas, including the following steps:

[0056] The high-chlorine and high-sulfur flue gas is introduced into the alkali solution absorption unit, and the flue gas enters the washing drum 105 from top to bottom, and collides with the alkali solution spraying from bottom to top in the opposite direction, so that the alkali solution washes the flue gas in the washing drum 105; the flow rate of the flue gas entering the washing drum 105 is 3m / s to 5m / s; the flow rate of the alkali solution entering the washing drum 105 is 0.25m / s to 0.5m / s;

[0057] After washing, the liquid falls into the washing liquid tank 101, and the gas enters the clean water immersion unit through the gas outlet pipe 107 to remove the residual alkali liquid in the gas;

[0058] The gas treated by the clean water washing unit enters the deep dechlorination unit, where the colloidal solution is first condensed under the action of the chlorine element in the gas, and then the adsorption fixed bed 302 adsorbs the residual pollutants in the gas.

[0059] In a specific implementation, the plant protein solution is a crude solution containing proteins extracted from plants. These proteins can come from different plant sources, such as soybeans, peas, wheat, etc., which will not be elaborated here.

[0060] Example 1

[0061] A purification system for high-chlorine and high-sulfur flue gas comprises three parts, which are connected in sequence: an alkali solution absorption unit, a clean water immersion unit and a deep dechlorination unit.

[0062] (1) Alkali absorption unit

[0063] The alkali solution absorption unit includes a washing liquid tank 101, a washing cylinder 105 and a gas outlet pipe 107 vertically arranged above the washing liquid tank 101, an air inlet pipe 106 connected to the top of the washing cylinder 105, a liquid inlet pipe 103 connected to the middle and lower end of the washing cylinder 105, and a nozzle 104 arranged inside the washing cylinder 105 and connected to the liquid inlet pipe 103;

[0064] The nozzle 104 includes a venturi nozzle 111 and a guide plate 110 with a built-in guide channel 113, which are connected in sequence. The venturi nozzle 111 is connected to the liquid inlet pipe 103; the guide plate 110 includes a plate body 112 and a guide channel 113 arranged on the plate body 112. The guide channels 113 are inclined and through-arranged, and there are 2 groups of them with evenly distributed outlets; the middle inner wall of the guide channel 113 is provided with spirally distributed guide ribs 114, and the number of spiral turns of the guide ribs 114 is 3 turns;

[0065] A passive rotating element 102 is disposed at the end of the washing tub 105. The passive rotating element 102 includes a horizontal rotating shaft and three sets of blades fixed to the outer wall of the rotating shaft.

[0066] A gas-liquid separation disc 108 is disposed at the end of the gas outlet pipe 107 . The gas-liquid separation disc 108 is a filter screen, and a cone extending downward is disposed in the middle thereof.

[0067] An air distribution plate 109 with a porous structure is arranged inside the washing tub 105 and below the air inlet pipe 106 , and the air distribution plate 109 is provided with evenly distributed through holes.

[0068] (2) Clean water washing unit

[0069] The clean water immersion unit includes a cleaning tank 201 with clean water inside and an injection element 202 for introducing airflow into the clean water. The injection element 202 is connected to the gas outlet pipe 107, and the injection element 202 includes a ventilation pipe and an aeration plate connected to the ventilation pipe. The aeration plate injects the airflow treated by the alkali solution absorption unit into the cleaning tank 201 to contact with the clean water.

[0070] (3) Deep dechlorination unit

[0071] The deep dechlorination unit comprises a deep dechlorination tank 301 with a colloidal solution inside, an adsorption fixed bed 302 inside the upper part of the deep dechlorination tank 301, and an aeration element 303 for introducing airflow into the colloidal solution. The colloidal solution is a plant protein solution; the filler of the adsorption fixed bed 302 is a molecular sieve or activated carbon.

[0072] Example 2

[0073] The difference between this embodiment and the first embodiment is only in the guide channels 113. In this embodiment, the number of the guide channels 113 is 3 groups.

[0074] Example 3

[0075] The difference between this embodiment and the first embodiment is only in the guide channels 113. In this embodiment, the number of the guide channels 113 is 4 groups.

[0076] Example 4

[0077] The only difference between this embodiment and Embodiment 1 is the number of spiral turns of the guide rib 114 . In this embodiment, the number of spiral turns of the guide rib 114 is 4.

[0078] Example 5

[0079] The only difference between this embodiment and Embodiment 1 is the number of spiral turns of the guide rib 114 . In this embodiment, the number of spiral turns of the guide rib 114 is 5.

[0080] Comparative Example 1

[0081] The only difference between this comparative example and Example 1 is the structure of the nozzle 104 . The nozzle 104 of this comparative example only includes a Venturi nozzle.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 1 is only the structure of the nozzle 104. The nozzle 104 of this comparative example is a Venturi nozzle + two groups of vertical guide channels + three circles of guide ribs.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 1 is only the structure of the nozzle 104. The nozzle 104 of this comparative example is a Venturi nozzle + two groups of inclined flow guide channels.

[0086] Under the condition of the same power pump body delivery, the liquid velocity and height sprayed from the nozzles of Examples 1 to 5 and Comparative Examples 1 to 3 were measured, and the comparison results are shown in Table 1.

[0087] Table 1

[0088] Test subjects Nozzle composition Spray speed m / s Spray height mm Comparative Example 1 Venturi nozzle 0.2 115 Comparative Example 2 Venturi nozzle + 2 sets of vertical diversion channels + diversion ribs 0.28 132 Comparative Example 3 Venturi nozzle + 2 sets of inclined diversion channels 0.27 130 Example 1 Venturi nozzle + 2 sets of inclined diversion channels + 3 circles of diversion ribs 0.35 147 Example 2 Venturi nozzle + 3 sets of inclined diversion channels + 3 circles of diversion ribs 0.40 155 Example 3 Venturi nozzle + 4 sets of inclined diversion channels + 3 circles of diversion ribs 0.42 158 Example 4 Venturi nozzle + 2 sets of inclined diversion channels + 4 circles of diversion ribs 0.39 152 Example 5 Venturi nozzle + 2 sets of inclined diversion channels + 5 circles of diversion ribs 0.38 150

[0089] It can be seen from the data in Table 1 that the improvement of the nozzle in the present invention effectively improves the speed and height of the alkali solution injection. It can be seen from the comparison of Comparative Examples 1 to 3 with Example 1 that the guide channel and the guide ribs both promote the speed and height of the injection, and the inclined guide channel is better than the vertical guide channel.

[0090] From the comparison of Example 1, Example 2 and Example 3, it can be seen that the speed and height of the spray increase with the increase of the number of the guide channels. When the number increases to a certain number, the amplification effect is limited. The reason is that when the number of the guide channels is too large, the number of sprayed liquid streams will also increase, and they will interfere with each other, which will affect the spray effect.

[0091] From the comparison of Example 1, Example 4 and Example 5, it can be seen that the speed and height of the jet increase with the increase in the number of guide ribs. When the number increases to a certain level, the amplification effect is limited. The reason is that the liquid speed at the outlet increases with the increase in the number of guide ribs, but when the number is too large, the liquid will collide with each other due to the excessive speed, thereby slowing down the speed.

[0092] Example 6

[0093] The purification system of Example 1 is used to purify high-chlorine and high-sulfur flue gas, comprising the following steps:

[0094] S1. The flue gas is passed through the air inlet pipe 106 into the top of the washing barrel 105 through the fan, and the flue gas is sprayed from top to bottom and then dispersed by the gas distributor 109; the alkali solution is passed through the pump body from the liquid inlet pipe 103 into the middle and lower end of the washing barrel 105, and then the nozzle 104 reversely sprays it from bottom to top into the flue gas airflow, and the gas-liquid turbulent contact realizes the washing of the flue gas by the alkali solution; wherein the flow rate of the flue gas entering the washing barrel 105 is 3m / s; the flow rate of the alkali solution entering the washing barrel 105 is 0.25m / s; the gas-liquid two phases form a high-speed turbulent contact in the gas-liquid mixing zone, and then fall onto the moving rotating element 102 under the action of gravity downstream, driving it to rotate, and at the same time, part of the gas and liquid phases rebound and rise to perform turbulent contact again, and finally the gas and liquid enter the washing liquid tank 101, the liquid is deposited under the action of gravity, and the gas is discharged through the gas outlet pipe 107, and the gas and liquid are further separated under the action of the gas-liquid separation disk 108;

[0095] S2, the gas is discharged from the gas outlet pipe 107 and then enters the cleaning tank 201 with built-in clean water through the jet element 202 composed of the fan, pipeline, aeration plate, etc., and the clean water is used as the cleaning liquid to clean the gas, and then discharged from the cleaning tank 201;

[0096] S3. The gas discharged from the cleaning tank 201 enters the deep dechlorination tank 301 containing the built-in plant protein solution through the aeration element 303 composed of a fan, a pipe, an aeration plate, etc. The colloidal solution condenses under the action of the chlorine element in the gas, and the gas continues to move upward, flows through the adsorption fixed bed filled with molecular sieves, and is finally discharged.

[0097] Example 7

[0098] The difference between this embodiment and embodiment 6 is that the flow rate of the flue gas entering the washing drum 105 is adjusted to 4 m / s, and the other reaction conditions are the same as those of embodiment 6.

[0099] Example 8

[0100] The difference between this embodiment and embodiment 6 is that the flow rate of the flue gas entering the washing drum 105 is adjusted to 5 m / s, and the other reaction conditions are the same as those of embodiment 6.

[0101] Example 9

[0102] The difference between this embodiment and embodiment 6 is that the flow rate of the alkali solution entering the washing drum 105 is adjusted to 0.4 m / s, and the other reaction conditions are the same as those in embodiment 6.

[0103] Example 10

[0104] The difference between this embodiment and embodiment 6 is that the flow rate of the alkali solution entering the washing drum 105 is adjusted to 0.5 m / s, and the other reaction conditions are the same as those in embodiment 6.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 6 is that the smoke enters the washing cylinder 105 without being dispersed through the gas distribution plate 109, and the other reaction conditions are the same as those of Example 6.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 6 is that the alkali solution absorption unit adopts a spray washing unit, specifically: the alkali solution is contacted with the flue gas by a top-down spraying method, and other reaction conditions are the same as those in Example 6.

[0109] Comparative Example 6

[0110] The difference between this comparative example and Example 6 is that no passive rotating element 102 is provided at the end of the washing drum 105 , and other reaction conditions are the same as those of Example 6.

[0111] Comparative Example 7

[0112] The difference between this comparative example and Example 6 is that step S3 is deleted, and other reaction conditions are the same as those of Example 6.

[0113] Comparative Example 8

[0114] The difference between this comparative example and Example 6 is that step S2 is deleted, and other reaction conditions are the same as those of Example 6.

[0115] The sulfur and chlorine components in the gas after purification treatment of Examples 6 to 10 and Comparative Examples 4 to 8 were measured, and the results are shown in Table 2.

[0116] Table 2

[0117]

[0118] It can be seen from the data in Table 2 that the purification system of the present invention can remove more than 95% of chlorine and more than 99% of sulfur in flue gas.

[0119] It can be seen from Examples 6 to 8 that as the air intake speed increases, the removal efficiency of chlorine and sulfur increases; however, when the speed increases to a certain value, it suppresses the speed of the alkali solution, which is not conducive to washing.

[0120] It can be seen from Examples 6, 9 and 10 that as the liquid inlet speed increases, the removal efficiency of chlorine and sulfur increases; however, when the speed increases to a certain value, the injection height is too large, which is not conducive to sufficient mixing of gas and liquid.

[0121] Comparison between Example 6 and Comparative Example 4 shows that without dispersion through the gas distributor 109, the removal efficiency of chlorine and sulfur is slightly reduced. The reason is that the activity range of the intake air is too small, resulting in insufficient gas-liquid mixing, which in turn affects the washing effect.

[0122] Comparison between Example 6 and Comparative Example 5 shows that the use of the spray washing unit significantly reduces the removal efficiency of chlorine and sulfur. The reason is that the spray washing limits the gas-liquid contact time and area, resulting in less absorption of chloride ions and sulfides, especially the very low chloride ion degradation efficiency.

[0123] Comparison between Example 6 and Comparative Example 6 shows that without the passive rotating element 102, the removal efficiency of chlorine and sulfur is slightly reduced. The reason is that the passive rotating element 102 increases the gas-liquid contact time.

[0124] Comparison between Example 6 and Comparative Example 7 shows that deleting step S3 significantly reduces the chlorine removal efficiency.

[0125] Comparison between Example 6 and Comparative Example 8 shows that the removal of step S2 slightly reduces the removal efficiency of chlorine and sulfur. The reason is that the gas flow contains alkali solution, which will affect the subsequent treatment units if it is not cleaned.

[0126] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A purification system for high-chlorine and high-sulfur flue gas, characterized in that: The purification system comprises: The alkali solution absorption unit is used for countercurrent contact between the flue gas and the alkali solution, and the alkali solution washes the flue gas to initially remove the chlorine and sulfur pollutants therein; The clean water immersion unit is used to clean the airflow after being treated by the alkali solution absorption unit to prevent the alkali solution in the airflow from entering the subsequent units; Deep dechlorination unit, used to deeply remove residual chloride ions; The alkaline solution absorption unit includes a washing liquid tank, a washing cylinder vertically arranged above the washing liquid tank and a gas outlet pipe, an air inlet pipe connected to the top of the washing cylinder, a liquid inlet pipe connected to the middle and lower ends of the washing cylinder, and a nozzle arranged inside the washing cylinder and connected to the liquid inlet pipe; the air inlet pipe allows the flue gas to enter the washing cylinder from top to bottom, and the nozzle sprays the alkaline solution into the flue gas flow from bottom to top in reverse, and the gas-liquid turbulent contact realizes the washing of the flue gas by the alkaline solution; the nozzle includes a venturi nozzle connected in sequence and a guide plate with a built-in guide channel; a passive rotating element is arranged at the end of the washing cylinder; and a gas-liquid separation plate is arranged at the end of the gas outlet pipe; The clean water immersion unit includes a cleaning tank containing clean water and an injection element for introducing air flow into the clean water; The deep dechlorination unit comprises a deep dechlorination tank with a colloidal solution inside, an adsorption fixed bed inside the upper part of the deep dechlorination tank, and an aeration element for introducing airflow into the colloidal solution.

2. A high-chlorine and high-sulfur flue gas purification system according to claim 1, characterized in that: The guide plate comprises a plate body and a guide channel arranged on the plate body. The guide channel is inclined and through-arranged, and the number of the guide channel is at least 2 groups.

3. A high-chlorine and high-sulfur flue gas purification system according to claim 2, characterized in that: The number of the guide channels is 2 to 4 groups, and the outlets are evenly distributed.

4. A high-chlorine and high-sulfur flue gas purification system according to claim 2 or 3, characterized in that: The middle inner wall of the guide channel is provided with spirally distributed guide ribs; the number of spiral turns of the guide ribs is 3 to 5.

5. A high-chlorine and high-sulfur flue gas purification system according to claim 1, characterized in that: The passive rotating element comprises a horizontal rotating shaft and at least three groups of blades fixed on the outer wall of the rotating shaft. The driving force for the rotation of the passive rotating element is the gas-liquid mixture flowing from top to bottom in the washing tub.

6. A high-chlorine and high-sulfur flue gas purification system according to claim 1, characterized in that: The gas-liquid separation disc is a filter screen, and the middle part is a cone extending downward.

7. A high-chlorine and high-sulfur flue gas purification system according to claim 1, characterized in that: An air distribution plate with a porous structure is arranged inside the washing cylinder and below the air inlet pipe.

8. A method for purifying high-chlorine and high-sulfur flue gas, characterized in that: The purification method adopts the purification system according to any one of claims 1 to 7; the purification method comprises the following steps: The high-chlorine and high-sulfur flue gas is introduced into the alkali solution absorption unit after being accelerated by the fan. The flue gas enters the washing drum from top to bottom after being accelerated by the fan, and collides with the alkali solution spraying from bottom to top in the opposite direction, so that the alkali solution washes the flue gas in the washing drum; The liquid after washing falls into the washing liquid tank, and the gas enters the clean water immersion unit through the gas outlet pipe to remove the residual alkali liquid in the gas; The gas treated by the clean water washing unit enters the deep dechlorination unit, where the colloidal solution is first condensed under the action of chloride ions in the gas, and then the residual pollutants in the gas are adsorbed by the adsorption fixed bed.

9. The method for purifying high-chlorine and high-sulfur flue gas according to claim 8, characterized in that: The flow rate of the flue gas entering the washing drum is 3m / s to 5m / s; the flow rate of the alkali solution entering the washing drum is 0.25m / s to 0.5m / s.

10. The method for purifying high-chlorine and high-sulfur flue gas according to claim 8, characterized in that: The colloidal solution is a plant protein solution; the filler of the adsorption fixed bed is a molecular sieve or activated carbon.

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