Resource recovery device for sodium nitrate granulation tail gas

Abstract

The utility model discloses a resource recovery device for sodium nitrate granulation tail gas. An expansion section cylinder is additionally arranged at a tower body at the top of a granulation tower; a spray washing unit, an efficient absorption unit, a blade reverse cleaning unit and an efficient demisting unit are sequentially arranged in the flowing direction of sodium nitrate granulation tail gas. The high-efficiency absorption unit is arranged in a filler box of an original external expansion barrel of the granulation tower, and the filler box is filled with high-efficiency filler; a high-efficiency demisting unit is arranged in the expansion section cylinder, and a fan is arranged behind the high-efficiency demisting unit, so that exhausted tail gas can be timely pumped out; a circulating washing tank is arranged at the bottom of the granulation tower, and circulating washing liquid collected into the circulating washing tank is fed into the spray washing unit through a circulating washing pump; and the external desalted water pipeline is connected with the circulating washing tank and the blade backwashing unit. The utility model solves the problems that the prilling tower is large in operation resistance and poor in dust removal effect, and sodium nitrate dust in tail gas cannot be recycled.

Description

Technical Field

[0001] The utility model belongs to the field of tail gas recovery, and particularly relates to a tail gas recovery device for sodium nitrate granulation. Background Technique

[0002] So far, large, medium and small-sized sodium nitrate granulation in China basically adopts sodium nitrate granulation towers for granulation. There are two types of traditional sodium nitrate granulation towers: mechanical ventilation and natural ventilation. During the sodium nitrate granulation process, the dust removal equipment (fan) causes a large operating resistance in the granulation tower, with poor dust removal effect, and the sodium nitrate dust in the tail gas cannot be recovered. Therefore, a simple dust removal and washing device is installed at the top of the granulation tower, but there are problems such as easy blockage and large operating resistance, which affect the normal operation of the granulation tower. In order to reduce the production resistance, the production unit removed it, resulting in the sodium nitrate dust in the exhausted tail gas not being recoverable. Most of it floats in the form of white particles on the device and the fan side, not only causing waste of sodium nitrate raw materials, harming the health of inspection and maintenance personnel, but also polluting the environment. The traditional tail gas treatment and recovery device for granulation towers not only fails to play its real role properly, but also is prone to scaling in the granulation tower due to the hygroscopicity of sodium nitrate. Content of the Utility Model

[0003] To solve the problems of large operating resistance in the granulation tower, poor dust removal effect, and non-recovery of sodium nitrate dust in the tail gas, the utility model provides a resource recovery device for sodium nitrate granulation tail gas, which completely solves the operating resistance of the granulation tower, making the content of sodium nitrate dust in the exhausted tail gas less than 10mg / Nm 3 , and also realizes the recovery of sodium nitrate dust through a circulation route.

[0004] The technical solution of the utility model is a resource recovery device for sodium nitrate granulation tail gas, which is characterized in that along the flow direction of sodium nitrate granulation tail gas at the tower body on the top of the granulation tower, a spray washing unit, a high-efficiency absorption unit, a blade backwashing unit, and a high-efficiency demisting unit are successively fixed; the high-efficiency demisting unit is arranged in an enlarged section cylinder body added to the tower body, and a fan is provided behind the high-efficiency demisting unit to timely extract the exhausted tail gas; the high-efficiency absorption unit is installed in the packing box of the original outer expansion cylinder body of the granulation tower, and the packing box is filled with packing; a circulating washing tank is arranged at the bottom of the granulation tower, and the circulating washing tank is connected to the spray washing unit through a circulating washing pump by pipeline; the off-site desalted water pipeline is connected to the circulating washing tank and the blade backwashing unit.

[0005] Furthermore, the spraying direction of the nozzles of the blade backwashing unit is the same as the tail gas flow direction.

[0006] Furthermore, the packing is installed at an angle perpendicular to the tail gas flow direction, and CY700 type wire mesh corrugated packing is adopted, and it is arranged in a three-sided ring shape in the packing box.

[0007] Furthermore, the spraying direction of the nozzles in the spray washing unit is perpendicular to the packing box, so that the washing liquid is evenly sprayed onto the entire surface of the packing.

[0008] The utility model has the following beneficial effects:

[0009] (1) Demineralized water is replenished only at the blade backwashing unit 3 and the circulating washing tank 8. Water is added for washing only when the blades need to be backwashed. No water is supplied usually, which plays a role in protecting the blades and realizes the system water circulation, saves water resources, and enables the system to operate stably.

[0010] (2) By adding a densitometer and a liquid level gauge at the circulating washing tank 8 in this device, when the sodium nitrate solution reaches a certain concentration, the external discharge valve of the sodium nitrate solution is controlled to make the sodium nitrate solution return to the system, achieving the purpose of recovering sodium nitrate dust, washing and recovering sodium nitrate in the tail gas to the greatest extent, and saving water as much as possible, improving the concentration of the washing liquid returning to the system. When the concentration is too small, the external discharge valve is closed and the valve of the circulating pipeline is opened wide to wash the sodium nitrate powder with the dilute sodium nitrate solution and achieve the purpose of concentrating the discharged sodium nitrate solution.

[0011] (3) The high-efficiency absorption unit 2 uses high-efficiency packing installed at an angle perpendicular to the gas flow direction, which can increase the gas-liquid contact area, thus saving installation space, saving packing, and reducing the expenditure on transformation funds. The CY700 type wire mesh corrugated packing is set and arranged in a three-sided ring shape. The main purpose is to save installation space and make the gas-liquid contact sufficient as much as possible, reduce the kinetic energy of the gas, and protect the packing.

[0012] (4) The spray washing unit 1 is mainly composed of a main spraying pipe. The spray washing unit is installed at least 0.2 m in front of the high-efficiency absorption unit. The nozzles can spray evenly and the impact force is not too large, reducing the service life of the packing; the spraying direction of the nozzles is perpendicular to the packing box, which can make the washing liquid evenly sprayed onto the entire surface of the packing, avoiding uneven spraying in local areas. The blade backwashing unit 3 is installed between the high-efficiency absorption unit 2 and the high-efficiency demisting unit 4, protecting the service life of the blades to the greatest extent and enabling the system to operate stably. Here, we use the blades as the main device, making full use of the existing distance to increase the buffer space of the gas in the blade box; the spraying direction is consistent with the gas flow direction, which can increase the positive kinetic energy of the gas flow and make the tiny droplets in the tail gas grow larger, facilitating the separation of the droplets; at the same time, preventing the blades from being blocked.

[0013] (5) This device can reduce the problem of large operating resistance of the sodium nitrate granulation tower and ensure the stable operation of the system.

[0014] (6) The high-efficiency demisting unit 4 is based on the original air duct section, with an enlarged section added. Rectangular demisting blades are installed in the enlarged section, without increasing the height of the granulation tower and saving installation space. (7) Compared with the traditional washing process for treating tail gas, this device can reduce the sodium nitrate particulate matter in the granulation tail gas to 10 mg / Nm 3 The following can minimize the waste of resources to the greatest extent and protect the air environment. Brief Description of the Drawings

[0015] Figure 1 is a schematic structural view of the present utility model;

[0016] Figure 2 is Figure 1 a partially enlarged schematic view of;

[0017] Figure 3 is Figure 1 a top view of;

[0018] Figure 4 is a schematic structural view of the top of a traditional granulation tower;

[0019] Figure 5 is Figure 4 a top view of;

[0020] Explanation of the reference numerals in the drawings: spray washing unit 1; high-efficiency absorption unit 2; blade backwashing unit 3; high-efficiency demisting unit 4; tower body 5; fan 6; granulation tower 7; circulating washing tank 8; circulating washing pump 9; enlarged section cylinder 10; wire mesh 11. Detailed Description of the Preferred Embodiment

[0021] As Figure 1 , Figure 2 shown, a resource recovery device for sodium nitrate granulation tail gas provided by the present utility model is located at the top of the granulation tower 7 and the tail gas outlet part. By transforming the part of the top of the granulation tower and the tail gas outlet, an enlarged section cylinder 10 is added at the tower body 5 at the top of the granulation tower 7. Along the flow direction of the sodium nitrate granulation tail gas, a spray washing unit 1, a high-efficiency absorption unit 2, a blade backwashing unit 3, and a high-efficiency demisting unit 4 are sequentially provided; the high-efficiency absorption unit 2 is installed in the original externally expanded cylinder of the granulation tower.

[0022] The spray washing unit 1 is mainly composed of a main spray pipe. The spraying direction of the spray head is perpendicular to the packing box, which can make the washing liquid evenly sprayed on the entire surface of the packing, avoiding uneven spraying in local areas.

[0023] In the enlarged section cylinder 10, a high-efficiency demisting unit 4 is provided. The high-efficiency demisting unit 4 is mainly composed of blades. A fan 6 is provided behind the high-efficiency demisting unit 4 to timely extract the discharged tail gas.

[0024] To solve the operating resistance of the granulation tower, a blade backwashing unit 3 is added between the high-efficiency absorption unit 2 and the high-efficiency demisting unit 4, which is mainly composed of nozzles. Using the blades as the main cleaning device, it makes full use of the existing distance to increase the buffer space of the gas in the blade box. The spraying direction of the nozzles is consistent with the gas flow direction, which can increase the forward kinetic energy of the gas flow, make the tiny droplets in the tail gas grow up, facilitate the separation of the droplets, and prevent the blades from being blocked. By spraying and washing with fresh desalted water regularly and quantitatively, the blockage problem of the subsequent high-efficiency demisting unit 4 can be solved.

[0025] The spray washing unit 1 and the blade backwashing unit 3 adopt nozzles with different precisions to achieve the optimal spraying effect.

[0026] A circulating washing tank 8 is provided at the bottom of the granulation tower 7. The circulating washing liquid collected in the circulating washing tank 8 is sent into the spray washing unit 1 through the circulating washing pump 9; the off-site desalted water pipeline is connected to the circulating washing tank 8, and desalted water is supplemented only at the blade backwashing unit 3 and the circulating washing tank 8. A densitometer and a liquid level gauge are added at the circulating washing tank 8.

[0027] The working process is as follows:

[0028] The sodium nitrate solution is sprayed down by the nozzles at the top of the granulation tower, meets the air from the side of the tower, and the air-dried sodium nitrate particles are discharged from the bottom of the tower, and the tail gas is discharged from the air duct on the side of the top of the tower.

[0029] First, it passes through the fog droplet area sprayed by the spray washing unit 1, and the dust particles are wetted, collided, and adhered. The large dust particles finally settle into the circulating washing tank 8 under the action of gravity. The gas continues to enter the high-efficiency absorption unit 2, where it continues to collide and adhere on the surface of the packing, and the fog droplets continue to coalesce and grow into large droplets, which settle under the action of gravity and are collected in the circulating washing tank 8. After the washed tail gas is sprayed by the blade backwashing unit 3, the flow kinetic energy of the gas flow increases. After colliding with the blades, it is more conducive to the growth and separation of tiny droplets, and at the same time, it can prevent the attachment of particulate matter on the blade surface and prevent the blades from being blocked; the large droplets settle under the action of gravity and are collected in the circulating washing tank 8. Finally, the sodium nitrate particles are removed by the high-efficiency demisting unit 4, so that the tail gas is discharged up to standard, and at the same time, the secondary recovery of sodium nitrate dust is realized.

[0030] Our device is installed on the only way of the tail gas. The tail gas passes through the spray washing unit 1, the high-efficiency absorption unit 2, the blade backwashing unit 3 and the high-efficiency demisting unit 4 in sequence, and then is extracted by the induced draft fan 6 and discharged into the atmosphere up to standard.

[0031] The input end of the PLC control system is respectively connected to the densitometer in the circulating washing tank and the desalted water inlet flowmeter; the output end is connected to the external discharge liquid valve.

[0032] During the process, the PLC control system controls the demineralized water to first fill the circulating washing tank 8 to two-thirds, and then pump it into the nozzles of the spray washing unit 1 by the circulating washing pump 9 to provide liquid for the high-efficiency packing of the high-efficiency absorption unit 2, enabling the tail gas to come into full contact with water. At this time, open the demineralized water of the blade backwashing unit 3, and run the device in trial operation. Do not close the demineralized water switch leading to the circulating washing tank 8 until the device stabilizes. Then open the washing liquid return system switch and seek the stable point of the system again. When the device runs stably, keep it running.

[0033] Part of the washing circulating water is stored in the circulating washing tank 8. When the solution in the circulating washing tank 8 reaches a certain concentration and runs stably, the dilute sodium nitrate solution is discharged into the system for recycling. During the process, the demineralized water switch leading to the circulating washing tank 8 is always open. To prevent blockage of the high-efficiency demisting unit 4, add fresh demineralized water to the blade backwashing unit 3 every hour and close it after spraying and washing for 10 minutes.

[0034] Assuming the initial dust is 150 mg / Nm 3 , under the condition of no insoluble impurities, this modified device can make the dust content in the exhaust gas of the granulation tower < 10 mg / Nm 3 .

Claims

1. A resource recovery device for the tail gas of sodium nitrate granulation, characterized in that, At the tower body (5) at the top of the granulation tower (7), along the flow direction of the sodium nitrate granulation tail gas, a spray washing unit (1), a high-efficiency absorption unit (2), a blade backwashing unit (3) and a high-efficiency demisting unit (4) are successively fixed; the high-efficiency demisting unit (4) is arranged in an enlarged section cylinder body (10) added at the tower body (5), and a fan (6) is arranged behind the high-efficiency demisting unit (4) to timely extract the discharged tail gas; the high-efficiency absorption unit (2) is installed in the packing box of the original outer expansion cylinder body of the granulation tower, and the packing box is filled with packing; a circulating washing tank (8) is arranged at the bottom of the granulation tower (7), and the circulating washing tank (8) is connected to the spray washing unit (1) through a circulating washing pump (9) by pipeline; the off-site desalted water pipeline is connected to the circulating washing tank (8) and the blade backwashing unit (3).

2. The resource recovery device for the tail gas of sodium nitrate granulation as described in claim 1, characterized in that, The spraying direction of the nozzles of the blade backwashing unit (3) is consistent with the tail gas flow direction.

3. The resource recovery device for the tail gas of sodium nitrate granulation according to claim 2, wherein, The packing is installed at an angle perpendicular to the tail gas flow direction, and CY700 type wire mesh corrugated packing is adopted, and is arranged in the packing box in a three-sided ring type.

4. The resource recovery device for the tail gas of sodium nitrate granulation according to claim 3, characterized in that, The spraying direction of the nozzles in the spray washing unit (1) is perpendicular to the packing box, so that the washing liquid is evenly sprayed on the entire surface of the packing.

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