Efficient wet desulfurization and defluorination system and method based on cascade regeneration cycle

Abstract

The invention relates to the field of industrial waste gas treatment, and discloses an efficient wet desulfurization and defluorination system and method based on cascade regeneration cycle, and the system comprises a collection pipeline, an air mixing box, an X-shaped pipeline, a high-temperature bag-type dust collector, an air supplement pipeline, a rotational flow plate tower group, a vertical dry filter, an activated carbon box, a frequency conversion fan and a chimney which are connected in sequence; the rotational flow plate tower group is connected with the spray liquid circulating system and comprises three stages of rotational flow plate towers which are connected in series, and a liquid accumulation box is arranged at the bottom of each stage of rotational flow plate tower; the spraying liquid circulating system comprises a first-stage circulating pool, a second-stage circulating pool and a third-stage circulating pool which are respectively connected with each stage of rotational flow plate tower; a filtrate outlet of the filter press connected with the primary circulating pool is connected with the secondary circulating pool, and a filter cake outlet part of the filter press is connected to the primary circulating pool; the pH value of the primary circulating pool is 5.0-6.0, the pH value of the secondary circulating pool is 6.5-7.5, and the pH value of the circulating pool is 10.0-11.0. According to the invention, equipment blockage caused by co-crystallization of fluoride and desulfurization products is avoided, and the desulfurizer is saved.

Description

Technical Field

[0001] The present invention relates to the field of industrial waste gas treatment, and in particular to a high-efficiency wet desulfurization and defluorination system and method based on a cascade regeneration cycle. Background Art

[0002] In industrial production, the operation of rotary kilns produces waste gas with complex components, including harmful components such as sulfur dioxide, fluorides, sulfides, VOCs, as well as fine carbon particles, fly ash and other particulate matter. Currently, the traditional wet desulfurization process has some urgent problems in treating such waste gas, such as:

[0003] 1. Poor adaptability to high-temperature exhaust gas: The exhaust gas temperature of the rotary kiln is high (usually >150°C). Traditional wet desulfurization equipment is easily deformed by heat, and high temperature reduces the SO2 / fluoride absorption efficiency;

[0004] 2. Difficulty in synergistic removal of multiple pollutants: Waste gas contains multiple components such as SO2, fluoride, VOCs, tar, etc., which cannot be removed simultaneously and efficiently by a single process. In particular, fluoride is prone to co-crystallization with desulfurization products (CaSO3 / CaSO4), causing equipment blockage;

[0005] 3. High operating costs: Traditional spray towers require continuous replenishment of fresh desulfurizers (such as limestone), resulting in low slurry recycling rates and large amounts of solid waste.

[0006] 4. The pipe in front of the dust collector is easily blocked and difficult to clean.

[0007] Based on this, the present application provides a high-efficiency wet desulfurization and defluorination system and method based on a cascade regeneration cycle to solve one of the above problems. Summary of the Invention

[0008] The present invention aims to solve the technical problems existing in the prior art. To this end, the present invention provides a high-efficiency wet desulfurization and defluorination system and method based on a cascade regeneration cycle.

[0009] The technical solution adopted by the present invention to solve its technical problem is:

[0010] In the first aspect, a high-efficiency wet desulfurization and defluorination system based on a cascade regeneration cycle is provided, comprising a collection pipe, an air mixing box, a vertical or inclined X-shaped pipe, a high-temperature bag dust collector, an air supply pipe, a swirl plate tower group, a vertical dry filter, an activated carbon box, a variable frequency fan and a chimney connected in sequence along the air flow direction; the swirl plate tower group is connected to a spray liquid circulation system, wherein: the swirl plate tower group comprises three stages of swirl plate towers connected in series, and a liquid accumulation tank for collecting spray liquid is provided at the bottom of each stage of the swirl plate tower; the spray liquid circulation system comprises a primary circulation pool connected to each stage of the swirl plate tower respectively. , a secondary circulation pool, and a tertiary circulation pool. Each circulation pool is divided into an oxidation pool, at least two sedimentation pools, and a pH adjustment pool by a partition. The oxidation pool of each circulation pool is connected to the liquid storage box of the corresponding cyclone plate tower, and the pH adjustment pool provides spray liquid for the cyclone plate tower; the filtrate outlet of the filter press connected to the primary circulation pool is connected to the oxidation pool of the secondary circulation pool, and the filter cake outlet part of the filter press is connected to the oxidation pool inlet of the primary circulation pool; the pH value of the primary circulation pool is 5.0-6.0, the pH value of the secondary circulation pool is 6.5-7.5, and the pH value of the circulation pool is 10.0-11.0.

[0011] In some optional embodiments, the calcium ion concentration in the primary circulation pool is maintained at 4000-5000 mg / L, and the spray liquid in the tertiary circulation pool is a Ca(OH)2 solution with a concentration of 15±2%.

[0012] In some optional embodiments, the filter cake back-mixing ratio in the primary circulation pool is 20-40%, and the moisture content of the back-mixed filter cake is ≤30%.

[0013] In some optional embodiments, both the air mixing box and the air supply duct are provided with an induced air duct, and the induced air duct is provided with an electric proportional valve.

[0014] In some optional embodiments, the X-shaped pipe is made of a round pipe, and a dust pushing plate for cleaning dust is provided on the top blind plate thereof, and the dust pushing plate is a semicircular plate.

[0015] In some optional embodiments, the oxidation tank, sedimentation tank and pH adjustment tank of each stage of the circulation pool are connected to the first-stage cyclone plate tower through pipelines to treat the exhaust gas generated by the circulation pool.

[0016] In some optional embodiments, each stage of the cyclone plate tower is installed on the same liquid accumulation tank, and a partition is provided between two adjacent stages of the cyclone plate tower in the liquid accumulation tank.

[0017] In some optional embodiments, an aeration pipe connected to a Roots blower unit is provided in the oxidation tank and pH adjustment tank of each stage of the circulation pool and the liquid accumulation tank of each stage of the cyclone plate tower.

[0018] In some optional embodiments, an intelligent control system is also included, which includes: a signal linkage module between the duct pressure transmitter and the variable frequency fan; a start-stop interlock module between the liquid level meter of the circulation tank and the slurry circulation pump; and a closed-loop control module between the pH meter of the circulation tank and the dosing pump.

[0019] In a second aspect, a high-efficiency wet desulfurization and defluorination method based on a cascade regeneration cycle is provided, comprising the following steps:

[0020] Step S1, collection and preliminary treatment of flue gas: The flue gas enters the air mixing box through the collection pipe. The air mixing box is equipped with an electric proportional valve to automatically adjust the introduction of fresh air to perform preliminary temperature regulation on the flue gas;

[0021] Step S2, dust particle removal: the flue gas conditioned by the air mixing box enters the high-temperature pulse bag dust collector through the X-shaped pipe to remove fine dust particles in the flue gas;

[0022] Step S3, cooling and harmful gas absorption: the flue gas after dust removal is cooled by fresh air supply through the pipeline, and then passes through the three-stage cyclone plate tower made of PPH material in sequence:

[0023] The first-stage cyclone plate tower sprays the slurry with a pH of 5.0-6.0 to remove 80-90% of SO2;

[0024] The secondary cyclone plate tower sprays the slurry with a pH of 6.5-7.5 to remove residual SO2 and 30-50% of fluoride;

[0025] The three-stage cyclone plate tower sprays the slurry with a pH of 10.0-11.0, removing ≥95% of fluoride;

[0026] Step S4, further purification and discharge: the flue gas after being treated by the cyclone plate tower enters the vertical dry filter in sequence to remove water vapor, then enters the activated carbon box to remove VOCs before being discharged into the air;

[0027] Step S5: After the saturated slurry in the primary circulation pool is filtered, 30% of the filter cake is mixed back into the primary pool, and the filtrate is transported to the secondary circulation pool.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention achieves targeted separation of pollutants in flue gas through cascade pH control in a three-stage circulation pool, avoiding equipment blockage caused by co-crystallization of fluoride and desulfurization products (CaSO3 / CaSO4), while increasing the fluoride removal rate from the conventional 70% to over 95%;

[0030] 2. It can save more than 35% of desulfurizer: the secondary circulation pool receives the filtrate from the primary circulation pool, which improves the utilization rate of the slurry and reduces the replenishment of fresh slurry. At the same time, the unreacted Ca(OH)2 (accounting for about 30%) in the filter cake of the primary circulation pool is recycled after back-mixing;

[0031] 3. The arrangement of the air mixing box and the supplementary distribution pipe can reduce the flue gas temperature, which is beneficial to the absorption efficiency of SO2 / fluoride;

[0032] 4. The X-shaped pipe adopts a vertical or inclined design, which can reduce the probability of pipe blockage compared to horizontally laid pipes. At the same time, the X-shaped structure design can clean the pipe through the dust pusher on the top of the pipe, which can solve the problem of pipe blockage simply and quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0034] Figure 1 This is a planar layout diagram of a high-efficiency wet desulfurization and defluorination system based on a cascade regeneration cycle provided by the present invention;

[0035] Figure 2 yes Figure 1 The connection structure diagram of the three-stage cyclone plate tower and the three-stage circulation pool is provided;

[0036] Figure 3 yes Figure 1 Schematic diagram of the X-shaped pipeline structure provided.

[0037] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0038] 1—collection duct, 2—air mixing box, 3—X-type duct, 3.1—blind plate, 3.2—ash pusher, 3.3—push rod, 4—high-temperature bag dust collector, 5—air supply duct, 6—swirl plate tower group, 6.1—swirl plate tower, 6.2—liquid accumulation tank, 7—vertical dry filter, 8—activated carbon box, 9—variable frequency fan, 10—chimney, 11—induced draft duct, 12—electric proportional valve, 13—spray liquid circulation system, 13.1—primary circulation pool, 13.2—secondary circulation pool, 13.3—tertiary circulation pool, 14—Roots blower unit. DETAILED DESCRIPTION

[0039] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] Example 1

[0043] As attached Figure 1 As shown, this embodiment provides a high-efficiency wet desulfurization and defluorination system based on a cascade regeneration cycle, comprising a collection pipe 1, an air mixing box 2, a vertical or inclined X-shaped pipe 3, a high-temperature bag dust collector 4 (pulse back-blow type), an air supply pipe 5, a cyclone plate tower group 6, a vertical dry filter 7, an activated carbon box 8, a variable frequency fan 9 and a chimney 10 connected in sequence along the air flow direction, wherein:

[0044] The collection pipes, air mixing boxes, X-shaped pipes, and air supply pipes are all made of 2205 duplex steel; the cyclone plate tower group, vertical dry filter, activated carbon box and its connecting pipes are all made of PPH material, among which: the vertical dry filter uses a glass fiber filter cartridge with a filtration accuracy of ≤0.3μm; the activated carbon box is filled with honeycomb activated carbon with an iodine value ≥800mg / g.

[0045] Preferably, the air mixing box 2 and the air supply duct 5 are both provided with an induced draft duct 11, and the air supply duct is provided with an electric proportional valve 12. The air mixing box can introduce fresh air through the electric proportional valve to initially cool the flue gas, and the flue gas after dust removal can be cooled again by introducing fresh air through the electric proportional valve on the air supply duct, so as to reduce the temperature of the flue gas entering the cyclone plate tower and improve the absorption efficiency of SO2 / fluoride in the cyclone plate tower.

[0046] Please refer to the instruction manual Figure 2 The cyclone plate tower group 6 is connected to the spray liquid circulation system 13, wherein: the cyclone plate tower group 6 includes three stages of cyclone plate towers 6.1 connected in series, and the bottom of each stage of the cyclone plate tower is provided with a liquid storage tank 6.2 for collecting the spray liquid. In a preferred embodiment: as shown in the attached Figure 2 As shown, each stage of the cyclone plate tower 6.1 of this embodiment is installed on the same liquid storage box 6.2, and a partition is provided between two adjacent stages of the cyclone plate tower in the liquid storage box to separate the corresponding liquid storage boxes of the three stages of the cyclone plate tower.

[0047] As attached Figure 2 As shown, the spray liquid circulation system 13 includes a primary circulation pool 13.1, a secondary circulation pool 13.2, and a tertiary circulation pool 13.3, which are respectively connected to each stage of the cyclone plate tower. Each stage of the circulation pool is divided into an oxidation pool, at least two sedimentation pools, and a pH adjustment pool by a partition. The oxidation pool and the sedimentation pool, the sedimentation pools, and the sedimentation pools and pH adjustment pools are connected. The oxidation pool of each stage of the circulation pool is connected to the liquid storage tank of the corresponding cyclone plate tower, and the pH adjustment pool provides spray liquid for the cyclone plate tower. The pH value of the primary circulation pool is 5.0-6.0, which allows the flue gas to remove 80-90% of SO2 in the primary cyclone plate tower. To ensure the desulfurization effect, the present embodiment maintains the calcium ion concentration in the primary circulation pool at 4000-5000 mg / L; the pH value of the secondary circulation pool is 6.5-7.5, which allows the flue gas to remove residual SO2 and 30-50% of fluoride in the secondary cyclone plate tower; the pH value of the circulation pool is 10.0-11.0, which allows the flue gas to remove more than 95% of fluoride in the tertiary cyclone plate tower. To ensure the defluorination effect, the spray liquid of the tertiary circulation pool is a Ca(OH)2 solution with a concentration of 15±2%. The present invention adopts a three-stage circulation pool cascade pH control to achieve targeted separation of pollutants in the flue gas, avoid equipment clogging caused by co-crystallization of fluoride and desulfurization products (CaSO3 / CaSO4), and at the same time increase the fluoride removal rate from the conventional 70% to more than 95%.

[0048] As attached Figure 2 As shown, in this embodiment, the sedimentation tank of each circulating pool is connected to a filter press, wherein the filtrate of the filter press of the primary circulating pool is connected to the oxidation tank of the secondary circulating pool, and the filtrate of the filter press of the secondary circulating pool and the tertiary circulating pool is connected to the oxidation tank of the secondary circulating pool and the tertiary circulating pool, respectively. The filter cake of the filter press of the primary circulating pool is partially mixed back to the inlet of the oxidation tank of the primary circulating pool, and the mixing ratio is 20-40%. The moisture content of the mixed filter cake is ≤30%, which can maintain the Ca(OH)2 activity in the primary circulating pool and reduce the amount of fresh desulfurizer. Overall, this design can save more than 35% of desulfurizer.

[0049] Preferably, as attached Figure 2 As shown, the oxidation tank, sedimentation tank and pH adjustment tank of each stage of the circulation pool are connected to the first-stage cyclone plate tower through pipelines to treat the exhaust gas generated by the circulation pool.

[0050] Preferably, as attached Figure 2 As shown, in this embodiment, the oxidation tank and pH adjustment tank of each stage of the circulation pool and the liquid storage tank of each stage of the cyclone plate tower are provided with an aeration pipe connected to the Roots blower unit 14 to prevent the slurry from settling in the liquid storage tank and the oxidation tank, and at the same time, the oxidation tank and the pH adjustment tank can also be aerated and mixed.

[0051] Preferably, as attached Figure 3As shown, the X-shaped duct 3 of this embodiment is made of a round tube, and a ash pusher 3.2 for cleaning is provided on the top blind plate 3.1 thereof, and the ash pusher 3.2 is a semicircular plate. The present invention adopts a vertical or inclined design for the X-shaped duct, which can reduce the probability of clogging of the duct compared to horizontally laid ducts. At the same time, the design of the X-shaped structure can clean the duct through the ash pusher at the top of the duct, which can solve the problem of duct blockage simply and quickly. When cleaning the duct, the pusher plate can be pushed downward to push the accumulated ash in the duct into the air mixing box or dust collector. The semicircular ash pusher does not affect the air supply effect of the duct, and ash cleaning can also be performed during operation. The ash pusher is controlled by the push rod 3.3 and can rotate 360° to achieve ash cleaning without dead angles in the duct.

[0052] Example 2

[0053] Based on Example 1, this embodiment also includes an intelligent control system, which includes: a signal linkage module between the duct pressure transmitter and the variable frequency fan, which can realize wind pressure adaptive variable frequency fan control based on the pressure transmitter; a closed-loop control module between the pH meter of the circulation pool and the dosing pump, which can realize automatic dosing of the circulation pool according to the pH value (dosing can be triggered when the pH deviation is controlled to be greater than 0.3); a start-stop interlock module between the liquid level meter of the circulation pool and the slurry circulation pump, which can realize automatic control of the start and stop of the circulation pump according to the liquid level in the circulation pool.

[0054] Example 3

[0055] This embodiment provides a high-efficiency wet desulfurization and defluorination method based on a cascade regeneration cycle, comprising the following steps:

[0056] Step S1, collection and preliminary treatment of flue gas: The flue gas enters the air mixing box through the collection pipe. The air mixing box is equipped with an electric proportional valve to automatically adjust the introduction of fresh air to perform preliminary temperature regulation on the flue gas;

[0057] Step S2, dust particle removal: the flue gas conditioned by the air mixing box enters the high-temperature pulse bag dust collector through the X-shaped pipe to remove fine dust particles in the flue gas;

[0058] Step S3, cooling and harmful gas absorption: the flue gas after dust removal is cooled by fresh air supply through the pipeline, and then passes through the three-stage cyclone plate tower made of PPH material in sequence:

[0059] The first-stage cyclone plate tower sprays the slurry with a pH of 5.0-6.0 to remove 80-90% of SO2;

[0060] The secondary cyclone plate tower sprays the slurry with a pH of 6.5-7.5 to remove residual SO2 and 30-50% of fluoride;

[0061] The three-stage cyclone plate tower sprays the slurry with a pH of 10.0-11.0, removing ≥95% of fluoride;

[0062] Step S4, further purification and discharge: the flue gas after being treated by the cyclone plate tower enters the vertical dry filter in sequence to remove water vapor, then enters the activated carbon box to remove VOCs before being discharged into the air;

[0063] Step S5: After the saturated slurry in the primary circulation pool is filtered, 30% of the filter cake is mixed back into the primary pool, and the filtrate is transported to the secondary circulation pool.

[0064] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high-efficiency wet desulfurization and defluorination system based on a cascade regeneration cycle, characterized by: It includes a collection duct, an air mixing box, a vertical or inclined X-shaped duct, a high-temperature bag dust collector, an air supply duct, a swirl plate tower group, a vertical dry filter, an activated carbon box, a variable frequency fan and a chimney connected in sequence along the airflow direction; The cyclone plate tower group is connected to a spray liquid circulation system, wherein: the cyclone plate tower group includes three stages of cyclone plate towers connected in series, and a liquid accumulation tank for collecting spray liquid is provided at the bottom of each stage of the cyclone plate tower; the spray liquid circulation system includes a primary circulation pool, a secondary circulation pool, and a tertiary circulation pool respectively connected to each stage of the cyclone plate tower, each stage of the circulation pool is divided into an oxidation pool, at least two sedimentation tanks, and a pH adjustment tank by a partition, the oxidation tank of each stage of the circulation pool is connected to the liquid accumulation tank of the corresponding cyclone plate tower, and the pH adjustment tank provides spray liquid for the cyclone plate tower; The filtrate outlet of the filter press connected to the primary circulation pool is connected to the oxidation pool of the secondary circulation pool, and the filter cake outlet of the filter press is connected to the oxidation pool inlet of the primary circulation pool; The pH value of the primary circulation pool is 5.0-6.0, the pH value of the secondary circulation pool is 6.5-7.5, and the pH value of the circulation pool is 10.0-11.

0.

2. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: The calcium ion concentration in the primary circulation pool is maintained at 4000-5000 mg / L, and the spraying liquid in the tertiary circulation pool is a Ca(OH)2 solution with a concentration of 15±2%.

3. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: The filter cake back-mixing ratio in the primary circulation pool is 20-40%, and the moisture content of the back-mixed filter cake is ≤30%.

4. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: The air mixing box and the air supply duct are both provided with an induced air duct, and the induced air duct is provided with an electric proportional valve.

5. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: The X-shaped pipeline is made of a round pipe, and a dust pushing plate for cleaning dust is arranged on the top blind plate thereof, and the dust pushing plate is a semicircular plate.

6. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: The oxidation tank, sedimentation tank and pH adjustment tank of each stage of the circulation pool are connected to the first-stage cyclone plate tower through pipelines to treat the exhaust gas generated by the circulation pool.

7. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: Each stage of the cyclone plate tower is installed on the same liquid accumulation box, and a partition is provided between two adjacent stages of the cyclone plate tower in the liquid accumulation box.

8. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: Aeration pipes connected to the Roots blower unit are provided in the oxidation tank and pH adjustment tank of each stage of the circulation pool and the liquid accumulation tank of each stage of the cyclone plate tower.

9. The high-efficiency wet desulfurization and defluorination system based on cascade regeneration cycle according to claim 1 is characterized in that: It also includes an intelligent control system, which includes: Signal linkage module between duct pressure transmitter and variable frequency fan; The liquid level gauge of the circulation pool and the start-stop interlock module of the slurry circulation pump; Closed-loop control module for the pH meter and dosing pump of the circulation pool.

10. The desulfurization and defluorination method of a high-efficiency wet desulfurization and defluorination system based on a cascade regeneration cycle according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, collection and preliminary treatment of flue gas: The flue gas enters the air mixing box through the collection pipe. The air mixing box is equipped with an electric proportional valve to automatically adjust the introduction of fresh air to perform preliminary temperature regulation on the flue gas; Step S2, dust particle removal: the flue gas conditioned by the air mixing box enters the high-temperature pulse bag dust collector through the X-shaped pipe to remove fine dust particles in the flue gas; Step S3, cooling and harmful gas absorption: the flue gas after dust removal is cooled by fresh air supply through the pipeline, and then passes through the three-stage cyclone plate tower made of PPH material in sequence: The first-stage cyclone plate tower sprays the slurry with a pH of 5.0-6.0 to remove 80-90% of SO2; The secondary cyclone plate tower sprays the slurry with a pH of 6.5-7.5 to remove residual SO2 and 30-50% of fluoride; The three-stage cyclone plate tower sprays the slurry with a pH of 10.0-11.0, removing ≥95% of fluoride; Step S4, further purification and discharge: the flue gas after being treated by the cyclone plate tower enters the vertical dry filter in sequence to remove water vapor, then enters the activated carbon box to remove VOCs before being discharged into the air; Step S5: After the saturated slurry in the primary circulation pool is filtered, 30% of the filter cake is mixed back into the primary pool, and the filtrate is transported to the secondary circulation pool.

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