Large-particle urea tail gas clean recovery treatment device and large-particle urea production system

Abstract

The utility model provides a large-particle urea tail gas clean recovery treatment device which comprises a granulator, an inner cyclone separator, a cyclone water film pickling device, a recovery circulating pump, an induced draft fan and the like, a tail gas inlet of the inner cyclone separator is positioned in an upper box body of the granulator; a gas phase outlet is formed in the top of a barrel body of the inner cyclone separator; the cyclone water film pickling device is sequentially provided with a spray washing unit, a cyclone water film washing unit and a recovery tank from top to bottom; a washing liquid outlet is formed in the lower end of the cyclone water film washing unit barrel and is connected with a liquid inlet of the recovery tank; a tail gas volute pipe inlet is welded on the outer barrel wall of the cyclone water film washing unit barrel; a gas phase outlet of the inner cyclone separator is connected with a tail gas volute pipe inlet of the cyclone water film washing unit; a liquid outlet of the recovery tank is connected with a recovery circulating pump, an outlet of the recovery circulating pump is connected with a liquid supplementing port and a spraying device, and a clean tail gas outlet is connected with an induced draft fan. The device effectively removes urea dust and free ammonia in the tail gas, and is high in recovery efficiency and stable in operation.

Description

Technical Field

[0001] The utility model relates to the field of large-particle urea production, in particular to a large-particle urea tail gas clean recovery and treatment device and a large-particle urea production system. Background Art

[0002] At present, manufacturers producing large urea granules mainly use fluidized bed granulation technology. During the urea production process, due to factors such as excessive granulation temperature, excessive moisture, and excessive fluidization wind speed, urea granules will break, thereby generating a large amount of dust. In order to avoid environmental pollution and improve the economic benefits of the device, it is generally necessary to clean the tail gas containing urea dust and recover the urea dust in the tail gas as much as possible. The current industry indicator requires that the dust mass concentration in the tail gas of the urea device is ≤30mg / m 3 , ammonia mass concentration ≤30mg / m 3 At present, wet scrubbing is usually used in industry to remove dust from tail gas of urea plant. The tail gas is sent to a wet scrubber and discharged into the atmosphere after being cooled and scrubbed.

[0003] According to actual production experience, the dust generated by the large-particle urea device mainly comes from equipment such as granulators, crushers and vibrating screens, and the dust generated in the granulation section accounts for more than 50% of the total dust in the device. This part of the granulation tail gas containing a large amount of urea dust is pumped to the wet scrubber through the upper outlet of the granulator. The scrubber is equipped with multiple nozzles and trays. The desalted water sprayed by the nozzle cools and washes the granulation tail gas. The urea dust in the tail gas is dissolved in the desalted water and collected at the bottom of the scrubber. It is sent to the evaporation section through a delivery pump as a recovered urea solution. The washed tail gas is sent to the chimney through an induced draft fan for discharge. However, the washing technology currently used still has many problems: the traditional wet scrubber sprays desalted water through the nozzle to form water mist to contact the tail gas in reverse, thereby washing the urea dust and free ammonia in the tail gas, but due to factors such as short residence time, small contact area, and large influence of air volume and wind speed, the washing effect is limited, and the urea dust in the tail gas cannot be stably removed, and it is difficult to meet the emission requirements. At the same time, since the partial pressure of free ammonia in the tail gas is very low, the absorption of free ammonia by water washing is limited. Data show that the concentration of free ammonia in the tail gas after water washing still reaches 70~80mg / m 3 Around, far from 30mg / m 3 emission requirements.

[0004] In order to improve the shortcomings of existing washing technology, Chinese patent CN220531088U discloses a large-particle urea tail gas dust treatment and recovery device, which redesigns the traditional wet scrubber and adds a preliminary washing device before the tail gas enters the scrubber, the purpose of which is to pre-clean the tail gas and fully mix the gas, liquid and solid phases. At the same time, multiple groups of spray devices and filler demisters are designed in the scrubber, the purpose of which is to increase the contact area and residence time of the gas-liquid two phases, so that the dissolution of urea dust in the tail gas is more thorough, and to a certain extent solves the problem of substandard washing effect of traditional scrubbers. However, due to the large number of internal parts of the scrubber, including multi-stage fillers and demisters, its pressure drop is significantly increased, which greatly increases the load of the induced draft fan and has high energy consumption; and its principle is still to use a water washing method, which cannot reduce the free ammonia in the tail gas to a level that meets the emission standards. Chinese patent CN219072556U discloses a fluidized bed granulator tail gas purification device, which is mainly composed of an ammonia removal device, a purification device, an induced draft fan, and an exhaust gas emission device in sequence. The ammonia removal device neutralizes and absorbs free ammonia in the tail gas by dilute acid spraying. The tail gas after ammonia removal enters the purification device, and the dust is adsorbed and purified by a dry process. The collected dust is collected in the ash hopper for dissolution and recovery. This method effectively solves the problem that free ammonia in the tail gas is difficult to remove, and urea dust is collected by adsorption and catalytic oxidation methods, so that the discharged tail gas meets national standards. However, in this method, the ammonia removal device will continue to produce dilute ammonium salts, which requires further steps to be added for treatment, increasing costs; and the packing tower is used to physically adsorb urea dust, and the packing layer is easily blocked, which needs to be cleaned and replaced regularly, reducing the stability of the device and increasing operating costs. In addition, the multi-stage packing layer also greatly increases the pressure drop of the equipment, increases the burden of the induced draft fan, and has high energy consumption.

[0005] In view of this, the present utility model is proposed. Utility Model Content

[0006] In order to solve the above technical problems, the utility model provides a new type of large-particle urea tail gas clean recovery and treatment device, which not only effectively removes urea dust and free ammonia in the tail gas, so that the tail gas meets the industry's environmental protection requirements and meets the emission standards, but also has high recovery efficiency, stable operation and controllable costs.

[0007] The utility model provides a large-particle urea tail gas clean recovery and treatment device, including a granulator, an inner cyclone separator, a cyclone water film pickling device, a recovery circulation pump and an induced draft fan;

[0008] The granulator comprises an upper box and a lower box having a granulation chamber and a cooling chamber;

[0009] The inner cyclone separator comprises an inner cyclone separator cylinder and an ash hopper connected to each other, the inner cyclone separator cylinder having an inner cyclone separator tail gas inlet located in the upper box, and the top of the inner cyclone separator cylinder is provided with an inner cyclone separator gas phase outlet extending out of the upper box; the ash hopper is located outside the granulator and has an inner cyclone separator solid phase outlet at the lower end;

[0010] The cyclone water film acid washer is a tower structure, and a spray washing unit with a clean exhaust gas outlet at the top, a cyclone water film washing unit and a recovery tank are arranged in sequence from top to bottom; the cyclone water film washing unit includes a cyclone water washing unit cylinder, a washing liquid outlet is arranged at the lower end of the cyclone water film washing unit cylinder and is connected to the liquid inlet of the recovery tank through a flange, an exhaust gas volute inlet is welded on the outer cylinder wall of the cyclone water film washing unit cylinder, the exhaust gas volute rotates and rises and is arranged in the cyclone water film washing unit cylinder, the exhaust gas volute outlet extends to the upper port of the cyclone water film washing unit cylinder where the gas phase outlet of the cyclone water film washing unit is arranged, and a liquid collecting chamber with an annular cavity and a liquid replenishing port is arranged on the top outer wall of the cyclone water film washing unit cylinder, and a liquid collecting plate and an overflow area are arranged in the liquid collecting chamber from top to bottom;

[0011] The gas phase outlet of the inner cyclone separator is connected to the exhaust gas volute inlet of the cyclone water film washing unit; the recovery tank liquid outlet arranged at the lower end of the recovery tank is connected to the recovery circulation pump, the outlet of the recovery circulation pump is connected to the liquid replenishment port and the various levels of spray devices in the spray washing unit, and the clean exhaust gas outlet is connected to the induced draft fan.

[0012] As an implementation manner, the exhaust gas volute inlet and the exhaust gas volute outlet are both arranged along a direction tangent to the cylinder of the cyclone water washing unit.

[0013] As an implementation manner, the overflow area is provided with a plurality of circles of evenly arranged overflow holes, and the overflow holes are circular holes that are opened obliquely upward.

[0014] As an implementation mode, the spray washing unit is respectively provided with a spray washing unit air inlet, a first-level spray device, a first-level tower plate, a second-level spray device, a second-level tower plate, a dilute acid liquid replenishment spray device, a demister and a clean exhaust gas outlet from bottom to top; the first-level spray device and the second-level spray device are respectively connected to the outlet of the recovery circulation pump, and the dilute acid liquid replenishment spray device is connected to an external dilute acid liquid replenishment storage device.

[0015] As an embodiment, the upper part of the inner cyclone separator cylinder is a cylindrical structure with a side wall provided with the inner cyclone separator tail gas inlet, and the lower part is an inverted cone structure and extends to the inner cavity of the ash hopper;

[0016] The upper box body has a plurality of granulation chambers and cooling chambers, wherein an integrated exhaust gas dust removal bin in the shape of a long cylinder is extended to the right above the cooling chamber at the end; the upper part of the inner cyclone separator cylinder is located in the exhaust gas dust removal bin.

[0017] As an embodiment, the liquid collecting plate is a circular tower plate with an opening in the middle for the exhaust gas to pass through and the tower plate is inclined downward on all sides.

[0018] As an embodiment, the recovery tank is in an inverted cone structure, the upper end of the inverted cone structure is set as the liquid inlet of the recovery tank, and the lower end of the inverted cone structure is set as the liquid outlet of the recovery tank.

[0019] As an implementation mode, it further comprises a density meter, a pH meter and a DCS system, and the recovery tank outlet arranged at the lower end of the recovery tank is connected to a recovery circulation pump after passing through the density meter and the pH meter.

[0020] As an implementation mode, the overflow area is composed of a plurality of overflow holes arranged at an opening distance of 2 to 4 cm; the overflow holes have an inclination angle of 30° to 45° relative to the vertical direction.

[0021] The utility model also provides a large-particle urea production system, which comprises the large-particle urea tail gas clean recovery and treatment device as described in any one of the above contents.

[0022] The utility model has the following beneficial effects:

[0023] 1. The large-particle urea tail gas clean recovery and treatment device of the utility model adopts an inner cyclone separator to perform dry pre-separation and recovery of urea particle dust in the tail gas of large-particle urea granulation, which can separate most of the urea dust and directly send it to the melting tank for recovery, reducing the burden of the scrubber and evaporation unit and reducing energy consumption. At the same time, the inner cyclone separator is integrated in the upper box body, which occupies a small area and has low cost.

[0024] 2. The large-particle urea tail gas clean recovery and treatment device of the utility model not only effectively removes urea dust and free ammonia in the tail gas of large-particle urea granulation, but also reduces the water vapor content in the tail gas, so that the final exhaust gas emissions meet the industry standards, achieving the purpose of clean and environmentally friendly exhaust gas emissions and preventing environmental pollution.

[0025] 3. The large-particle urea tail gas clean recovery and treatment device of the utility model has a simple structure, stable operation, low maintenance cost, small equipment pressure drop, small induced draft fan load, low energy consumption, and is suitable for industrial promotion. It is a green technology that meets the requirements of the new strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the technical solution of the utility model and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the utility model and do not constitute a limitation on the technical solution of the utility model.

[0027] Figure 1 It is a schematic structural diagram of the large-particle urea tail gas clean recovery and treatment device described in the utility model.

[0028] Figure 2 yes Figure 1 Schematic diagram of the partial structure of the mid-exhaust volute inlet.

[0029] Description of labels:

[0030] 1-granulator, 11-upper box, 12-lower box, 13-exhaust dust removal bin, 2-inner cyclone separator, 21-exhaust inlet of inner cyclone separator, 22-inner cyclone separator cylinder, 23-inner cyclone separator solid phase outlet, 24-inner cyclone separator gas phase outlet, 25-ear support, 26-ash hopper, 3-cyclone water film pickling device, 4-recovery tank, 41-recovery tank liquid inlet, 42-recovery tank liquid outlet, 5-cyclone water film washing unit, 51-washing liquid outlet, 52-exhaust volute pipe inlet , 53-cyclone water film washing unit cylinder, 54-liquid collecting chamber, 55-liquid replenishing port, 56-overflow area, 57-liquid collecting plate, 58-gas phase outlet of cyclone water film washing unit, 6-spray washing unit, 61-air inlet of spray washing unit, 62-first-stage spraying device, 63-first-stage tower plate, 64-second-stage spraying device, 65-second-stage tower plate, 66-dilute acid liquid replenishing spraying device, 67-demister, 68-clean tail gas outlet, 7-recovery circulation pump, 8-induced draft fan, 9-density meter, 10-pH meter. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] Example 1

[0033] A large granular urea tail gas clean recovery and treatment device, such as Figure 1 As shown, it includes a granulator 1, an internal cyclone separator 2, a cyclone water film pickling device 3, a recovery circulation pump 7, an induced draft fan 8, a density meter 9 and a pH meter 10.

[0034] The granulator 1 includes an upper box 11 and a lower box 12. The upper box 11 is provided with a plurality of chambers in the horizontal direction, specifically six in this case, wherein the first to third chambers are granulation chambers, the fourth to sixth chambers are cooling chambers, and a long cylindrical exhaust dust removal bin 13 is provided extending to the right above the sixth chamber of the upper box 11, and the exhaust dust removal bin 13 is an integrated structure with the upper box 11.

[0035] The lower box 12 is an existing technology that has been used since the 1990s. The main structural features are: the lower box 12 is a rectangular box, which is divided into 5 chambers by a partition. From left to right, there are 2 fluidized granulation chambers and 3 cooling chambers. The bottom of the fluidized granulation chamber is provided with a fluidizing air inlet and an atomizing air inlet, and the bottom of the cooling chamber is provided with a cooling air inlet. The upper part of the lower box 12 is a porous plate, and a large number of special openings are distributed on the porous plate. The function achieved is to make the urea crystals entering the granulator in a fluidized state on the porous plate, and the urea solution is sprayed at a certain pressure onto the urea crystals suspended on the fluidized bed, so that they continue to grow into qualified particles, move backwards under the action of gravity and fluidized air, and are sent to subsequent processes after cooling. This part is not the innovation point of the utility model and will not be repeated.

[0036] The inner cyclone separator 2 includes an inner cyclone separator cylinder 22 and an ash hopper 26. The upper part of the inner cyclone separator cylinder 22 is a cylindrical structure with an inner cyclone separator tail gas inlet 21 on the side wall, and the lower part of the inner cyclone separator cylinder 22 is an inverted cone structure and extends to the inner cavity of the ash hopper 26. The lower end of the ash hopper 26 is an inverted cone structure and is provided with an inner cyclone separator solid phase outlet 23. The top of the inner cyclone separator cylinder 22 is provided with an inner cyclone separator gas phase outlet 24 and extends to the inside of the cylindrical structure.

[0037] An ear-type support 25 is also provided on the side wall of the upper part of the inner cyclone separator cylinder 22, and openings are respectively provided on the top and bottom walls of the exhaust gas dust removal bin 13. The gas phase outlet 24 of the inner cyclone separator extends from the opening at the top of the exhaust gas dust removal bin 13, and the lower end of the inner cyclone separator cylinder 22 extends out of the opening of the bottom wall of the exhaust gas dust removal bin 13. The ear-type support 25 is connected to the bottom wall of the exhaust gas dust removal bin 13, so that the upper part of the inner cyclone separator cylinder 22 is located inside the exhaust gas dust removal bin 13, and the lower part of the inner cyclone separator cylinder 22 is located outside the granulator 1.

[0038] In specific applications, one inner cyclone separator 2 may be installed, or a plurality of inner cyclone separators 2 may be installed in parallel, depending on the production scale and exhaust gas conditions.

[0039] The cyclone water film pickling device 3 is a tower structure, which is divided into three parts: upper, middle and lower parts, that is, a spray washing unit 6, a cyclone water film washing unit 5 and a recovery tank 4 are arranged in sequence from top to bottom; a clean exhaust gas outlet 68 is arranged at the top of the spray washing unit 6, and the clean exhaust gas outlet 68 is connected to the induced draft fan 8 to discharge it into the atmosphere.

[0040] The cyclone water film washing unit 5 comprises a washing liquid outlet 51 , an exhaust gas volute inlet 52 , a cyclone water film washing unit cylinder 53 , a liquid collecting chamber 54 , a liquid replenishing port 55 , an overflow area 56 , a liquid collecting plate 57 and a cyclone water film washing unit gas phase outlet 58 .

[0041] The washing liquid outlet 51 is provided at the lower end of the cyclone water film washing unit cylinder 53 and is connected to the liquid inlet 41 of the recovery tank 4 through a flange.

[0042] like Figure 2 As shown, the exhaust gas volute inlet 52 is welded on the outer wall of the cyclone water film washing unit cylinder 53, and the exhaust gas volute inlet 52 and the exhaust gas volute outlet (not marked) are tangent to the cyclone water film washing unit cylinder 53. The tube path of the exhaust gas volute is at a certain angle to the cyclone water film washing unit cylinder 53, and the specific optional angle is 0~15° (excluding 0°). The exhaust gas enters the cyclone water film washing unit cylinder 53 tangentially from the exhaust gas volute inlet 52 and rotates upward.

[0043] The liquid collecting chamber 54 is installed on the outer wall of the top of the cyclone water film washing unit cylinder 53, and has an overall cylindrical structure. The top plate and the bottom plate of the liquid collecting chamber 54 are connected to the outer wall of the cyclone water film washing unit cylinder 53 to form an annular cavity. The liquid collecting chamber 54 is provided with a liquid replenishing port 55, which is connected to the circulation pump 7, and can send the supplementary washing liquid sent by the recycling circulation pump 7 into the liquid collecting chamber 54. The inside of the liquid collecting chamber 54 is provided with an overflow area 56, which is composed of overflow holes arranged at a certain distance. The overflow hole is a circular hole that is inclined upward to ensure that a layer of water film is formed on the cylinder wall of the cyclone water film washing unit cylinder 53 when the washing liquid overflows from the overflow hole. The liquid collecting plate 57 is arranged above the overflow area 56, and the gas phase outlet 58 of the cyclone water film washing unit is arranged at the upper port of the cyclone water film washing unit cylinder 53 and is connected to the lower port of the spray washing unit 6 through a flange, so that the gas coming out of the cyclone water film washing unit 5 enters the spray washing unit 6.

[0044] Specifically, the liquid collecting plate 57 is a circular plate with an opening in the middle for the exhaust gas to pass through and the four sides of the plate are inclined downward (the inclination angle relative to the horizontal direction can be preferably 5-15 degrees). Under the action of gravity, the collected washing liquid is continuously sent to the liquid collecting chamber 54 as the source of the water film washing liquid formed by the cyclone water film washing unit 5.

[0045] As an example, the overflow area 56 is composed of overflow holes arranged at a certain distance, the hole distance is preferably 2-4 cm, and 2-3 layers of overflow holes are preferably arranged. Further, the overflow hole is a circular hole that is inclined upward, and the inclination angle relative to the vertical direction is preferably 30°-45°.

[0046] When the equipment is running stably, the washing liquid in the liquid collecting chamber 54 continuously overflows from the overflow area 56 to the inner wall of the cyclone water film washing unit cylinder 53, and forms a layer of water film flowing downward along the inner wall of the cyclone water film washing unit cylinder 53 under the action of gravity. After the exhaust gas enters the cyclone water film washing unit 5, due to the action of centrifugal force, the urea dust particles in the exhaust gas are thrown to the cylinder wall, and then adhered to the water film and remain along the cylinder wall. The washing liquid enters the lower recovery tank 4 for buffering and collection.

[0047] The recovery tank 4 is an inverted cone structure, the upper end of the inverted cone structure is set as the recovery tank liquid inlet and is directly connected to the washing liquid outlet 51 of the cyclone water film washing unit 5 through a flange, and the recovery tank liquid outlet 42 set at the lower end of the inverted cone structure is connected to the recovery circulation pump 7 through a pipeline. A density meter 9 and a pH meter 10 are installed at the inlet of the recovery circulation pump 7 for real-time monitoring of the density and pH value of the circulating liquid, and these data are used to control the direction of the circulating liquid in the recovery tank 4 and whether to open the dilute acid replenishment pipeline.

[0048] The cyclone water film pickling device 3 of the utility model does not need to be provided with a packing layer, has a relatively low pressure drop, a small load on the induced draft fan 8, low energy consumption, and is equally effective in dust removal and ammonia removal.

[0049] The outlet of the recovery circulation pump 7 is connected to the spray washing unit 6 and the cyclone water film washing unit 5 through pipelines, so as to facilitate the circulation liquid to be sent into the cyclone water film acid washer 3 at a stable pressure for circulation.

[0050] As a specific example, the spray washing unit 6 is respectively provided with a spray washing unit air inlet 61, a first-level spray device 62, a first-level tower plate 63, a second-level spray device 64, a second-level tower plate 65, a dilute acid liquid replenishment spray device 66, a demister 67 and a clean tail gas outlet 68 from bottom to top, and the outlet of the recovery circulation pump 7 is respectively connected to the liquid replenishment port 55, the first-level spray device 62 and the second-level spray device 64 through three pipelines. The dilute acid liquid replenishment spray device 66 is connected to the external dilute acid liquid replenishment storage device, and the dilute acid liquid replenishment can be selected from dilute nitric acid, dilute sulfuric acid or organic acid (formic acid), etc. When the pH meter 10 monitors that the pH value reaches 5.5~6, the DCS system controls the opening of the dilute acid liquid replenishment spray device 66 at the top of the spray washing unit 6 for acid replenishment until the pH value reaches 2~3.

[0051] As an optional solution, the outlet of the recycling pump 7 is provided with a three-way valve, which is further connected to the external evaporation unit. The DCS system monitors and analyzes the pH value and density value in real time and controls the switching of the valve. When the density meter 9 detects that the urea in the circulating liquid coming out of the recovery tank 4 reaches a certain density, the valve is switched to pump the circulating liquid to the evaporation unit to recycle the urea. For example, the density reaches 1.11~1.15g / cm 3 When the three-way valve after the circulation recovery pump 7 is switched, the washing liquid is sent to the evaporation unit.

[0052] The following is an analysis of the important working process of the large-particle urea tail gas clean recovery and treatment device of the utility model:

[0053] During normal operation, there is a slight positive pressure inside the granulator 1, and the tail gas containing urea granule dust and free ammonia generated during the granulation process is pumped to the subsequent process section under the action of the induced draft fan 8. The tail gas first enters the inner cyclone separator cylinder 22 along the tangential direction through the inner cyclone separator tail gas inlet 21, and the tail gas changes from linear motion to circular motion, and moves in a spiral shape along the cylinder wall of the inner cyclone separator cylinder 22 toward the inverted cone structure at the lower part. Under the action of centrifugal force, the urea granule dust is thrown toward the cylinder wall. When the dust contacts the cylinder wall, it loses its inertial force and enters the ash hopper 26 downward under the action of gravity. The inner cyclone separator solid phase outlet 23 of the ash hopper 26 is connected to the melting tank. The utility model performs dry pre-separation and recovery of urea granule dust in the tail gas of large-particle urea granulation through this setting, and can separate most of the urea dust and directly send it to the melting tank for recovery, which reduces the burden of the scrubber and evaporation unit and reduces energy consumption.

[0054] During the process of rotating and descending, the exhaust gas continuously flows into the central part of the inner cyclone separator cylinder 22, forming a radial airflow, constituting a rotating upward inner cyclone flow. The exhaust gas with most of the urea dust removed is discharged upward from the gas phase outlet 24 of the inner cyclone separator, and then enters the cyclone water film washing unit cylinder 53 tangentially through the volute inlet 52 of the cyclone water film washing unit 5, and rotates upward. Due to the action of centrifugal force, the urea dust particles in the exhaust gas are thrown to the cylinder wall, and then adhered to the water film, left along the cylinder wall, and enter the lower recovery tank 4 for collection and buffering.

[0055] The tail gas after dust removal by the cyclone water film washing unit 5 enters the spray washing unit 6 upwards, and the first-level spray device 62 and the second-level spray device 64 are supplied with acidic washing liquid by the recovery circulation pump 7. The nozzles of the first-level spray device 62 and the second-level spray device 64 atomize the acidic washing liquid into fine water droplets, and the tail gas contacts the acidic water mist in countercurrent upwards, and the free ammonia in the tail gas reacts with the acid, and is fully adsorbed and neutralized on the first-level tower plate 62 and the second-level tower plate 64. When the pH meter 10 on the bottom pipeline of the pickling device detects that the pH of the circulating acidic washing liquid reaches 5.5~6, the dilute acid replenishment spray device 66 at the top of the spray washing unit 6 is automatically controlled by the DCS system to open, so as to enhance the ability of the circulating liquid in the system to absorb free ammonia. The tail gas after ammonia removal continues to go upwards and passes through the top demister 67 for demisting and dehydration, and then reaches the emission standard. The tail gas that meets the standard is pumped by the induced draft fan 8 from the clean tail gas outlet 68 at the top of the cyclone water film pickling device 3 and discharged into the atmosphere. The final exhaust gas emissions meet industry standards, achieving the goal of clean and environmentally friendly exhaust gas emissions and preventing environmental pollution.

[0056] Although the implementation methods disclosed in the utility model are as above, the above contents are only implementation methods adopted to facilitate the understanding of the utility model, and are not used to limit the utility model. Any technician in the field to which the utility model belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the utility model, but the scope of patent protection of the utility model shall still be based on the scope defined in the attached claims.

Claims

1. A large-particle urea tail gas clean recovery and treatment device, comprising a granulator, an inner cyclone separator, a cyclone water film pickling device, a recovery circulation pump and an induced draft fan, characterized in that: The granulator comprises an upper box and a lower box having a granulation chamber and a cooling chamber; The inner cyclone separator comprises an inner cyclone separator cylinder and an ash hopper connected to each other, the inner cyclone separator cylinder having an inner cyclone separator tail gas inlet located in the upper box, and the top of the inner cyclone separator cylinder is provided with an inner cyclone separator gas phase outlet extending out of the upper box; the ash hopper is located outside the granulator and has an inner cyclone separator solid phase outlet at the lower end; The cyclone water film acid washer is a tower structure, and a spray washing unit with a clean tail gas outlet at the top, a cyclone water film washing unit and a recovery tank are arranged in sequence from top to bottom; The cyclone water film washing unit comprises a cyclone water film washing unit cylinder, a washing liquid outlet is arranged at the lower end of the cyclone water film washing unit cylinder and is connected to the liquid inlet of the recovery tank through a flange, an exhaust gas volute inlet is welded on the outer cylinder wall of the cyclone water film washing unit cylinder, the exhaust gas volute rotates and rises and is arranged in the cyclone water film washing unit cylinder, the exhaust gas volute outlet extends to the upper port of the cyclone water film washing unit cylinder where the gas phase outlet of the cyclone water film washing unit is arranged, a liquid collecting chamber having an annular cavity and a liquid replenishing port is arranged on the top outer wall of the cyclone water film washing unit cylinder, and a liquid collecting plate and an overflow area are arranged from top to bottom in the liquid collecting chamber; The gas phase outlet of the inner cyclone separator is connected to the exhaust gas volute inlet of the cyclone water film washing unit; the recovery tank liquid outlet arranged at the lower end of the recovery tank is connected to the recovery circulation pump, the outlet of the recovery circulation pump is connected to the liquid replenishment port and the various levels of spray devices in the spray washing unit, and the clean exhaust gas outlet is connected to the induced draft fan.

2. The large-particle urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The exhaust gas volute inlet and the exhaust gas volute outlet are both arranged along a direction tangent to the cylinder of the cyclone water washing unit.

3. The large-particle urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The overflow area is provided with a plurality of circles of evenly arranged overflow holes, and the overflow holes are circular holes that are opened obliquely upward.

4. The large-particle urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The spray washing unit is provided with a spray washing unit air inlet, a first-level spray device, a first-level tower plate, a second-level spray device, a second-level tower plate, a dilute acid liquid replenishment spray device, a demister and a clean tail gas outlet from bottom to top; the first-level spray device and the second-level spray device are respectively connected to the outlet of the recovery circulation pump, and the dilute acid liquid replenishment spray device is connected to an external dilute acid liquid replenishment storage device.

5. The large granular urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The upper part of the inner cyclone separator cylinder is a cylindrical structure with a side wall provided with the inner cyclone separator tail gas inlet, and the lower part is an inverted cone structure and extends to the inner cavity of the ash hopper; The upper box body has a plurality of granulation chambers and cooling chambers, wherein an integrated exhaust gas dust removal bin in the shape of a long cylinder is extended to the right above the cooling chamber at the end; the upper part of the inner cyclone separator cylinder is located in the exhaust gas dust removal bin.

6. The large granular urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The liquid collecting plate is a circular plate with an opening in the middle for tail gas to pass through and the surrounding areas of the plate being inclined downward.

7. The large-particle urea tail gas clean recovery and treatment device according to claim 1 is characterized in that: The recovery tank is in an inverted cone structure, the upper end of the inverted cone structure is set as the liquid inlet of the recovery tank, and the lower end of the inverted cone structure is set as the liquid outlet of the recovery tank.

8. The large granular urea tail gas clean recovery and treatment device according to claim 4, characterized in that: It also includes a density meter, a pH meter and a DCS system. The recovery tank outlet arranged at the lower end of the recovery tank is connected to a recovery circulation pump after passing through the density meter and the pH meter. When the pH meter monitors that the pH value reaches 5.5-6, the DCS system controls the opening of the dilute acid replenishing spray device on the top of the spray washing unit to replenish acid until the pH value reaches 2-3.

9. The large-particle urea tail gas clean recovery and treatment device according to claim 8 is characterized in that: The outlet of the recovery circulation pump is connected to the external evaporation unit through a three-way valve, and the DCS system monitors and analyzes the pH value and density value in real time and controls the switching of the valve; When the density meter detects that the urea in the circulating liquid flowing out of the recovery tank reaches the set density, the valve is switched to pump the circulating liquid to the evaporation unit to recycle the urea.

10. A large granular urea production system, characterized in that: It comprises the large particle urea tail gas clean recovery and treatment device as described in any one of claims 1 to 9.

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