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

Abstract

The application provides a high-chlorine and high-sulfur flue gas purification system and purification method, and belongs to the technical field of waste gas treatment. The purification system comprises a lye absorption unit, a clean water immersion washing unit and a deep chlorine removal unit. The lye absorption unit comprises a washing liquid tank, a washing cylinder vertically arranged above the washing liquid tank and a gas outlet pipe, a gas inlet pipe connected with the top end of the washing cylinder, a liquid inlet pipe connected with the middle and lower end of the washing cylinder, and a nozzle arranged in the washing cylinder and connected with the liquid inlet pipe. The nozzle comprises a Venturi nozzle and a guide disc with an internal guide channel connected in sequence. A passive rotating element is arranged at the end of the washing cylinder. A gas-liquid separation disc is arranged at the end of the gas outlet pipe. The deep chlorine removal unit comprises a deep chlorine removal tank with a colloidal solution, an adsorption fixed bed and a gas blowing element. The lye absorption unit, the clean water immersion washing unit and the deep chlorine removal unit are arranged in a reverse washing mode, so that the chlorine ions and sulfur trioxide in the flue gas are efficiently removed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste gas treatment, and particularly relates to a high-chlorine and high-sulfur flue gas purification system and a purification method. BACKGROUND

[0002] Flue dust is the main waste gas in the metallurgical industry, and its main components are solid particles and part of flue gas. The commonly used flue dust treatment method is bag dust removal. Since the flue gas contains a certain amount of chloride and sulfur trioxide (sulfuric acid anhydride), the dew point of sulfur trioxide is increased after the flue gas is cooled by water spraying in the quenching tower. In combination with the presence of chloride, the equipment corrosion is obviously intensified. When the chloride in the bag flue dust exceeds 10%, the bag pressure difference rises obviously. If the influence of sulfur trioxide and chloride is ignored, the resistance of the bag dust collector fluctuates greatly, and in severe cases, it directly causes the bag to be scrapped, resulting in shutdown.

[0003] Therefore, the existing research direction is to add a preliminary purification method at the front end of the bag dust removal process to remove chloride and sulfur trioxide, so as to reduce their adverse effects on the subsequent bag dust removal process. The specific method is to add liquid alkali in the quenching tower spraying system, to prepare a suitable concentration of alkali solution and water solution in the quenching tower system by proportioning, to preliminarily intercept and react chloride and sulfur trioxide (sulfuric acid anhydride) in the quenching tower process, and to eliminate the influence on the subsequent bag dust collection.

[0004] The above method has the following defects: (1) limited removal efficiency, because the flue dust generated by metallurgy is generally from a high-temperature smelting furnace, and its temperature is relatively high, which will quickly rise and be discharged, and the contact time and area of the flue dust with the absorption liquid (such as liquid alkali) in the spraying system are limited, resulting in that the amount of chloride and sulfide absorbed is small, and the chloride degradation efficiency is very low; (2) easy to block, because the flue dust contains a large amount of solid particles, which can easily cause pipe blockage in the quenching tower spraying system. SUMMARY

[0005] In view of this, the present application aims to provide a high-chlorine and high-sulfur flue gas purification system and purification method, which aims to solve at least one technical problem in the background art.

[0006] The present application is implemented as follows:

[0007] The present application provides a high-chlorine and high-sulfur flue gas purification system in the first aspect, which comprises:

[0008] An alkali solution absorption unit is used for countercurrent contact of flue gas and alkali solution, and the alkali solution washes the flue gas to preliminarily remove chloride and sulfur pollutants therein;

[0009] A clean water immersion washing unit is used for cleaning the gas flow after the alkali solution absorption unit, to avoid the entry of alkali solution in the gas flow into the subsequent unit;

[0010] a deep chlorine removal unit for deeply removing residual chlorine ions;

[0011] The alkali liquor absorption unit comprises a washing liquid tank, a washing cylinder vertically arranged above the washing liquid tank and a gas outlet pipe, an air inlet pipe connected with the top end of the washing cylinder, a liquid inlet pipe connected with the middle and lower end of the washing cylinder, and a spray head arranged in the washing cylinder and connected with the liquid inlet pipe; the air inlet pipe is used to introduce the flue gas into the washing cylinder from top to bottom, the spray head is used to spray the alkali liquor into the flue gas from bottom to top, and the gas-liquid turbulent flow contact is used to realize the washing of the flue gas by the alkali liquor; the spray head comprises a Venturi nozzle and a flow guide disc with a built-in flow guide channel; the end of the washing cylinder is provided with a passive rotating element; and the end of the gas outlet pipe is provided with a gas-liquid separation disc.

[0012] The clean water immersion washing unit comprises a clean water washing tank and a gas injection element used to introduce the gas flow into the clean water.

[0013] The deep chlorine removal unit comprises a deep chlorine removal tank with a built-in colloidal solution, an adsorption fixed bed arranged in the upper part of the deep chlorine removal tank, and a gas blowing element used to introduce the gas flow into the colloidal solution.

[0014] Further, the flow guide disc comprises a disc body and flow guide channels arranged on the disc body, and the flow guide channels are inclined and through.

[0015] Further, the number of the flow guide channels is 2-4 groups, and the outlets are uniformly distributed.

[0016] Further, the inner wall of the flow guide channel is provided with helically distributed flow guide ribs, and the number of the helical turns of the flow guide ribs is 3-5 turns.

[0017] Further, the passive rotating element comprises a horizontal rotating shaft and at least 3 groups of blades fixed on the outer wall of the rotating shaft, and the driving force of the passive rotating element is the gas-liquid mixture flowing from top to bottom in the washing cylinder.

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

[0019] Further, a gas distribution disc with a porous structure is arranged in the washing cylinder and below the air inlet pipe.

[0020] The second aspect of the present application provides a purification method of high-chlorine and high-sulfur flue gas, which adopts 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 liquor absorption unit after being accelerated by the fan, the flue gas is introduced into the washing cylinder from top to bottom after being accelerated by the fan, collides with the alkali liquor sprayed from bottom to top, and the washing of the flue gas by the alkali liquor is realized in the washing cylinder;

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

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

[0024] Further, the flow rate of the flue gas entering the washing cylinder is 3 m / s to 5 m / s; and the flow rate of the lye entering the washing cylinder is 0.25 m / s to 0.5 m / s.

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

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

[0027] 1. The present application sets the lye absorption unit, the clean water immersion washing unit and the deep chlorine removal unit for reverse washing, so that the chloride ions and sulfur trioxide in the flue gas are efficiently removed.

[0028] 2. The lye absorption unit of the present application realizes high-speed reverse collision of gas-liquid two phases, forms a highly turbulent gas phase mixing zone, and the gas-liquid two phases appear in the form of foam or mist and present high-speed turbulent flow contact. In this process, the contact surface area is large and constantly moving and updating, thereby achieving high-efficiency washing effect.

[0029] 3. The present application utilizes the colloidal properties of the plant protein solution and the characteristics of the chlorine element as an electrolyte to efficiently remove the chlorine element in the flue gas; and in combination with the adsorption fixed bed, the deep purification of the flue gas is realized.

[0030] 4. The present application sets the flow guide channel, the flow guide disc and the flow guide rib to obtain a larger liquid spraying area and a higher liquid spraying speed, thereby strengthening the washing effect of the lye on the flue gas.

[0031] 5. The present application sets the passive rotating element to increase the turbulent flow contact time of the gas-liquid two phases, thereby realizing washing efficiency increase. DETAILED DESCRIPTION

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

[0033] Figure 2 It is a schematic diagram of the overall and partial structure of the spray head in the purification system of the present application;

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

[0035] Figure 4 Figure 1 is a schematic diagram of the top view of the gas-liquid separation disc in the purification system of the present application.

[0036] Figure 1 is a schematic diagram of the top view of the gas-liquid separation disc in the purification system of the present application.

[0037] 201- cleaning tank, 202- air injection element;

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

[0039] In order to make the purpose, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present application and do not limit the present application.

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

[0041] a lye absorption unit for countercurrent contact of flue gas and lye, the lye washing the flue gas to preliminarily remove chlorine and sulfur pollutants therein;

[0042] a clean water immersion washing unit for cleaning the gas stream treated by the lye absorption unit to avoid the lye in the gas stream entering the subsequent unit;

[0043] a deep dechlorination unit for deep removal of residual chlorine ions;

[0044] The lye absorption unit, the clean water immersion washing unit and the deep dechlorination unit are connected through pipelines, and further comprise matching valves, pump bodies, measuring instruments and the like, the structure, composition and connection of which are conventionally arranged and not marked in the figure, which will not be described in detail herein.

[0045] The lye absorption unit comprises a washing liquid tank 101, a washing cylinder 105 vertically arranged above the washing liquid tank 101 and a gas outlet pipe 107, an air inlet pipe 106 connected with the top end of the washing cylinder 105, a liquid inlet pipe 103 connected with the middle and lower end of the washing cylinder 105, and a spray head 104 arranged inside the washing cylinder 105 and connected with the liquid inlet pipe 103. After being accelerated by a fan, the flue gas enters the washing cylinder 105 from top to bottom through the air inlet pipe 106, and the lye is sprayed into the gas stream of the flue gas from bottom to top by the spray head 104, so that the gas-liquid turbulent contact realizes the washing of the flue gas by the lye.

[0046] ​In the washing cylinder 105, the gas-liquid two-phase high-speed counter-attacks, when the momentum reaches the balance, a highly turbulent gas phase mixing area is formed, the gas-liquid two-phase appears in the form of foam or mist and is in high-speed turbulent contact, the contact surface area is large and is constantly moving and updating, thereby achieving high washing efficiency. The height of the washing cylinder 105 is generally not less than 1000mm, between 1000mm and 1600mm; the inner diameter is generally not less than 100mm, between 100mm and 150mm, which can be adjusted according to actual needs.

[0047] Due to the gas-liquid two-phase counter-current contact, the liquid phase moves from bottom to top, and its momentum has a greater impact on the washing effect. Therefore, the spray head 104 is improved, which includes a Venturi nozzle 111 and a flow guide disc 110 with a built-in flow guide channel 113 connected in sequence, as shown in Figure 2 Figure 2 (a) is a front view of the spray head 104, (b) is a top view of the flow guide disc 110, and (c) is a sectional view of (b) along the A-A direction; the Venturi nozzle 111 is connected with the liquid inlet pipe 103, and the Venturi nozzle is designed according to the Bernoulli jet principle with reasonable geometric surface parameters, which can form a large flow circulation. When the high-speed liquid passes through the Venturi nozzle, it drives the liquid around it to enter the jet to form a circulation.

[0048] The flow guide disc 110 includes a disc body 112 and a flow guide channel 113 arranged on the disc body 112, the flow guide channel 113 is arranged in an inclined and penetrating manner, the number of the flow guide channel 113 is at least 2 groups (preferably 2 groups to 4 groups) and the outlets are uniformly distributed; the flow guide disc 110 is used to obtain a larger liquid spraying area and a higher liquid spraying speed; the inner wall of the flow guide channel 113 is provided with a spiral flow guide rib 114, the number of spiral turns of the flow guide rib 114 is 3-5 turns, and the flow guide rib 114 is used to guide the rotation of the liquid jet to further strengthen the function of the flow guide disc 110.

[0049] In the washing cylinder 105, although the gas-liquid two-phase is in high-speed turbulent contact in the gas-liquid mixing area under the action of the spray flow, the alkali solution will fall freely under the action of gravity and vertically enter the washing liquid tank 101, in order to further improve the washing effect, the passive rotating element 102 is arranged at the end of the washing cylinder 105; as shown in Figure 3 The passive rotating element 102 includes a horizontal rotating shaft and at least 3 groups of blades fixed on the outer wall of the rotating shaft, the driving force of the passive rotating element 102 is the gas-liquid mixture flowing from top to bottom in the washing cylinder 105, along with the flow of the alkali solution, the passive rotating element 102 slows down the falling speed, and along with the rotation, the gas-liquid two-phase is in turbulent contact again, realizing the washing efficiency.

[0050] ​After the washing in the washing cylinder 105, the gas-liquid two-phase enters the washing liquid tank 101, in which the liquid is deposited under the action of gravity, and the gas is discharged through the gas outlet pipe 107. Since the flue gas is high-temperature waste 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 a large amount of liquid alkali, which is in the form of gas mist, so a gas-liquid separation disc 108 is arranged at the end of the gas outlet pipe 107, as shown in the figure; the gas-liquid separation disc 108 is a filter screen, and the middle part is a downwardly extending cone. Through mechanical collision, due to the different densities and different speeds of the gas and the liquid, part of the liquid will be deposited and fall after being blocked by the gas-liquid separation disc 108. Figure 4

[0051] After the flue gas is accelerated by the fan, it is vertically downwardly introduced into the washing cylinder 105 through the air inlet at the top, and is concentrated below the air inlet pipe 106, resulting in uneven distribution of the gas. The present application is provided with a porous gas distribution disc 109 in the washing cylinder 105 and below the air inlet pipe 106. The gas distribution disc 109 is provided with uniformly distributed through holes, so that the flue gas introduced from the top is uniformly dispersed when passing through the gas distribution disc 109, and continues to fall downward after passing through each small hole, and is mixed with the alkali solution sprayed by the spray head 104, which is beneficial to the completion of more uniform jet flow of the flue gas in the washing cylinder 105.

[0052] The clean water immersion washing unit includes a clean water tank 201 with clean water, and a gas injection element 202 for introducing the gas flow into the clean water.

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

[0054] The main forms of chlorine elements in the flue gas are chloride ions, chlorides, chlorates and organic chlorines. In the high-temperature smelting process, organic chlorine substances may generate inorganic compounds such as chloride ions, chlorides and chlorates through sublimation and evaporation. At the same time, chemical reactions between chlorides and organic substances may be triggered in the incineration process to generate new organic chlorine substances. The plant protein solution has colloidal properties, and the chlorine elements in the flue gas can act as electrolytes, so that the plant protein solution is coagulated, and then the chlorine elements in the flue gas are removed; the adsorption fixed bed 302 is used to adsorb residual gas pollutants, such as sulfides and carbon dioxide which are not completely absorbed by the alkali absorption unit.

[0055] In specific implementation, the above-mentioned 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 cylinder 105 from top to bottom and collides with the alkali solution sprayed from bottom to top in a reverse direction, so that the washing of the flue gas by the alkali solution is realized in the washing cylinder 105; the flow rate of the flue gas entering the washing cylinder 105 is 3 m / s-5 m / s; and the flow rate of the alkali solution entering the washing cylinder 105 is 0.25 m / s-0.5 m / s;

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

[0058] The gas treated by the clean water immersion washing unit enters the deep chlorine removal unit, is coagulated by the colloidal solution in the gas, and then the residual pollutants in the gas are adsorbed by the adsorption fixed bed 302.

[0059] In a specific implementation, the plant protein solution is a crude extraction solution containing proteins extracted from plants, and the proteins can come from different plant sources such as soybeans, peas, wheat, etc., which are not described in detail here.

[0060] Example 1

[0061] A purification system for high-chlorine and high-sulfur flue gas, the purification system comprising an alkali solution absorption unit, a clean water immersion washing unit and a deep chlorine removal unit connected in sequence.

[0062] (1) Alkali solution absorption unit

[0063] The alkali solution absorption unit comprises a washing liquid tank 101, a washing cylinder 105 vertically arranged above the washing liquid tank 101 and a gas outlet pipe 107, a gas inlet pipe 106 connected with the top end of the washing cylinder 105, a liquid inlet pipe 103 connected with the middle and lower end of the washing cylinder 105, and a spray head 104 arranged inside the washing cylinder 105 and connected with the liquid inlet pipe 103.

[0064] The spray head 104 comprises a Venturi nozzle 111 and a guide disc 110 with built-in guide channels 113 connected in sequence, and the Venturi nozzle 111 is connected with the liquid inlet pipe 103; the guide disc 110 comprises a disc body 112 and guide channels 113 arranged on the disc body 112, the guide channels 113 are arranged in an inclined and penetrating manner, the number of the guide channels 113 is 2 groups and the outlets are uniformly distributed; the inner wall of the guide channels 113 is provided with helically distributed guide ribs 114, and the number of the helical turns of the guide ribs 114 is 3 turns.

[0065] A passive rotating element 102 is arranged at the end of the washing cylinder 105, and the passive rotating element 102 comprises a horizontal rotating shaft and 3 groups of blades fixed on the outer wall of the rotating shaft.

[0066] A gas-liquid separation disc 108 is arranged at the end of the gas outlet pipe 107, which is a filter screen with a downwardly extending cone in the middle.

[0067] A porous gas distribution disc 109 is arranged inside the washing cylinder 105 below the gas inlet pipe 106, which is provided with uniformly distributed through-holes.

[0068] (2) Fresh water soaking unit

[0069] The fresh water soaking unit comprises a washing tank 201 containing fresh water and a gas injection element 202 for introducing gas flow into the fresh water. The gas injection element 202 is connected to the gas outlet pipe 107 and comprises a gas passage pipe and an aeration disc connected to the gas passage pipe, which sprays the gas flow treated by the alkali liquid absorption unit into the washing tank 201 to contact with the fresh water.

[0070] (3) Deep dechlorination unit

[0071] The deep dechlorination unit comprises a deep dechlorination tank 301 containing a colloidal solution, an adsorption fixed bed 302 arranged in the upper part of the deep dechlorination tank 301, and a gas blowing element 303 for introducing gas flow into the colloidal solution. The colloidal solution is a plant protein solution, and the filler of the adsorption fixed bed 302 is molecular sieve or activated carbon.

[0072] Example 2

[0073] The difference between this example and Example 1 is only in the flow guide channel 113, which is in three groups in this example.

[0074] Example 3

[0075] The difference between this example and Example 1 is only in the flow guide channel 113, which is in four groups in this example.

[0076] Example 4

[0077] The difference between this example and Example 1 is only in the number of spiral turns of the flow guide rib 114, which is four turns in this example.

[0078] Example 5

[0079] The difference between this example and Example 1 is only in the number of spiral turns of the flow guide rib 114, which is five turns in this example.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 1 is only in the structure of the spray head 104, which only comprises a Venturi nozzle in this comparative example.

[0082] Comparative Example 2

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

[0084] Comparative Example 3

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

[0086] The liquid velocity and height sprayed by the spray heads of Examples 1 to 5 and Comparative Examples 1 to 3 were determined under the condition of the same power pump delivery, and the comparison results are shown in Table 1.

[0087] Table 1

[0088]

[0089] As can be seen from the data in Table 1, the improvement of the spray head of the present application effectively improves the velocity and height of the caustic liquid spray. As can be seen from the comparison between Comparative Examples 1 to 3 and Example 1, both the flow guide channels and the flow guide ribs promote the velocity and height of the spray, and the inclined flow guide channels are superior to the vertical flow guide channels.

[0090] As can be seen from the comparison between Example 1, Example 2 and Example 3, the velocity and height of the spray increase with the increase in the number of flow guide channels, but the increase effect is limited when the number reaches a certain amount. The reason is that when the number of flow guide channels is too large, the number of liquid streams sprayed will also increase, and interference between them will affect the spraying effect.

[0091] As can be seen from the comparison between Example 1, Example 4 and Example 5, the velocity and height of the spray increase with the increase in the number of flow guide ribs, but the increase effect is limited when the number reaches a certain amount. The reason is that the liquid velocity at the outlet increases with the increase in the number of flow guide ribs, but when the number is too large, the liquid will collide with each other, thereby slowing down the velocity.

[0092] Example 6

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

[0094] S1, the flue gas enters the top end of the washing cylinder 105 from the air inlet pipe 106 by the fan, the flue gas is sprayed from top to bottom, and then is dispersed by the gas distribution disc 109; the alkali solution enters the middle and lower end of the washing cylinder 105 from the liquid inlet pipe 103 by the pump body, and then is sprayed into the flue gas stream from bottom to top by the nozzle 104, 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 cylinder 105 is 3 m / s; the flow rate of the alkali solution entering the washing cylinder 105 is 0.25 m / s; the gas-liquid two-phase forms high-speed turbulent contact in the gas-liquid mixing area, and then falls onto the dynamic rotating element 102 under the action of gravity, drives the rotation of the dynamic rotating element 102, at the same time, part of the gas-liquid phase rebounds upward to be in turbulent contact again, and finally the gas-liquid enters 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-liquid is further separated under the action of the gas-liquid separation disc 108;

[0095] S2, the gas is discharged from the gas outlet pipe 107, enters the cleaning tank 201 containing clean water through the jet element 202 composed of the fan, the pipeline and the aeration disc, and is cleaned by the clean water as the cleaning liquid, and then is discharged from the cleaning tank 201;

[0096] S3, the gas discharged from the cleaning tank 201 enters the deep chlorine removal tank 301 containing the plant protein solution through the air element 303 composed of the fan, the pipeline and the aeration disc, the colloidal solution is coagulated under the action of the chlorine element in the gas, the gas continues to move upward, flows through the adsorption fixed bed filled with molecular sieve, and is finally discharged.

[0097] Example 7

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

[0099] Example 8

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

[0101] Example 9

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

[0103] Example 10

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

[0105] Comparative Example 4

[0106] The comparative example is different from example 6 in that the flue gas does not pass through the gas distribution disc 109 for dispersion after entering the washing cylinder 105, and other reaction conditions are the same as example 6.

[0107] Comparative example 5

[0108] The comparative example is different from example 6 in that the alkali liquid absorption unit adopts a spray washing unit, specifically, the alkali liquid is contacted with the flue gas by a top-down spraying method, and other reaction conditions are the same as example 6.

[0109] Comparative example 6

[0110] The comparative example is different from example 6 in that the passive rotating element 102 is not arranged at the end of the washing cylinder 105, and other reaction conditions are the same as example 6.

[0111] Comparative example 7

[0112] The comparative example is different from example 6 in that step S3 is deleted, and other reaction conditions are the same as example 6.

[0113] Comparative example 8

[0114] The comparative example is different from example 6 in that step S2 is deleted, and other reaction conditions are the same as example 6.

[0115] The sulfur and chlorine components in the gas after purification treatment in example 6 to example 10, comparative example 4 to comparative example 8 are determined, and the results are shown in table 2.

[0116] Table 2

[0117]

[0118] From the data in table 2, it can be known that the purification system of the present application can remove more than 95% of chlorine and more than 99% of sulfur in the flue gas.

[0119] It can be known from example 6 to example 8 that as the speed of the inlet gas increases, the removal efficiency of chlorine and sulfur increases; but when the speed increases to a certain value, it suppresses the speed of the alkali liquid, which is not conducive to washing.

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

[0121] It can be known from the comparison of example 6 and comparative example 4 that without passing through the gas distribution disc 109 for dispersion, the removal efficiency of chlorine and sulfur decreases slightly, because the activity range of the inlet gas is too small, which leads to insufficient mixing of gas and liquid, and further affects the washing effect.

[0122] As can be seen from the comparison between Example 6 and Comparative Example 5, the removal efficiency of chlorine and sulfur is greatly reduced by using the spray washing unit, because the gas-liquid contact time and area are limited by the spray washing, resulting in less absorption of chloride ions and sulfides, and the degradation efficiency of chloride ions is very low.

[0123] As can be seen from the comparison between Example 6 and Comparative Example 6, the removal efficiency of chlorine and sulfur is slightly reduced by not setting the passive rotating element 102, because the passive rotating element 102 improves the gas-liquid contact time.

[0124] As can be seen from the comparison between Example 6 and Comparative Example 7, the removal efficiency of chlorine is greatly reduced by deleting step S3.

[0125] As can be seen from the comparison between Example 6 and Comparative Example 8, the removal efficiency of chlorine and sulfur is slightly reduced by deleting step S2, because the gas stream contains lye, and if not cleaned, it will affect the subsequent processing units.

[0126] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A system for cleaning high-chlorine high-sulfur flue gas, characterized by, The purification system comprises: An alkali liquor absorption unit for countercurrent contact of flue gas and alkali liquor, the alkali liquor washing the flue gas to preliminarily remove chlorine and sulfur pollutants in the flue gas; A clean water immersion washing unit for washing the gas flow treated by the alkali liquor absorption unit to avoid the alkali liquor in the gas flow entering the subsequent unit; A deep chlorine removal unit for deep removal of residual chlorine ions; The alkali liquor absorption unit comprises a washing liquid tank, a washing cylinder vertically arranged above the washing liquid tank and a gas outlet pipe, an air inlet pipe connected with the top end of the washing cylinder, a liquid inlet pipe connected with the middle and lower end of the washing cylinder, and a nozzle arranged in the washing cylinder and connected with the liquid inlet pipe; the air inlet pipe is used for introducing the flue gas into the washing cylinder from top to bottom, the nozzle is used for spraying the alkali liquor into the gas flow of the flue gas from bottom to top, and gas-liquid turbulent contact is used to realize washing of the flue gas by the alkali liquor; the nozzle comprises a Venturi nozzle and a guide disc with a built-in guide channel; the guide disc comprises a disc body and guide channels arranged on the disc body; the guide channels are inclined and through, and the number of the guide channels is at least 2 groups; a guide rib spirally distributed in the middle inner wall of the guide channel; the number of spiral turns of the guide rib is 3-5 turns; a passive rotating element is arranged at the end of the washing cylinder; and a gas-liquid separation disc is arranged at the end of the gas outlet pipe. The clean water immersion washing unit comprises a clean water washing tank and a gas injection element for introducing the gas flow into the clean water. The deep chlorine removal unit comprises a deep chlorine removal tank with a built-in colloidal solution, an adsorption fixed bed arranged in the upper part of the deep chlorine removal tank, and a gas blowing element for introducing the gas flow into the colloidal solution.

2. A system for cleaning high-chloride and high-sulfur flue gas according to claim 1, characterized in that, The number of the guide channels is 2-4 groups, and the outlets are uniformly distributed.

3. The system for cleaning high-chlorine and high-sulfur flue gas according to claim 1, characterized in that, The passive rotating element comprises a horizontal rotating shaft and at least 3 groups of blades fixed on the outer wall of the rotating shaft; and the driving force of the passive rotating element is the gas-liquid mixture flowing from top to bottom in the washing cylinder.

4. The system for cleaning high-chlorine and high-sulfur flue gas according to claim 1, characterized by, The gas-liquid separation disc is a filter screen, and the middle part is a downwardly extending cone.

5. The system for cleaning high chlorine and high sulfur flue gas according to claim 1, wherein A gas distribution disc with a porous structure is arranged in the washing cylinder and below the air inlet pipe.

6. A method for cleaning high-chlorine high-sulfur flue gas, characterized by, The purification method adopts the purification system according to any one of claims 1-5; and the purification method comprises the following steps: The high-chlorine and high-sulfur flue gas is introduced into the alkali liquor absorption unit after being accelerated by a fan; the flue gas is introduced into the washing cylinder from top to bottom after being accelerated by the fan, collides with the alkali liquor sprayed from bottom to top, and the washing of the flue gas by the alkali liquor is realized in the washing cylinder; After the washing is completed, the liquid falls into the washing liquid tank, and the gas enters the clean water immersion washing unit through the gas outlet pipe to remove the residual alkali liquor in the gas; The gas treated by the clean water immersion washing unit enters the deep chlorine removal unit, first coagulates under the action of the chlorine ions in the colloidal solution in the gas, and then the residual pollutants in the gas are adsorbed by the adsorption fixed bed.

7. A method of cleaning high-chlorine high-sulfur flue gas according to claim 6, characterized in that, The flow rate of the flue gas entering the washing cylinder is 3-5 m / s, and the flow rate of the alkali liquor entering the washing cylinder is 0.25-0.5 m / s.

8. A method of cleaning high-chlorine high-sulfur flue gas according to claim 6, characterized by, The colloidal solution is a plant protein solution; and the filler of the adsorption fixed bed is molecular sieve or activated carbon.

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