Desulfurization wastewater zero-discharge anti-wall-sticking drying tower

Abstract

The utility model discloses a desulfurization waste water zero discharge wall sticking prevention drying tower, which comprises a flue gas inlet pipe, an ash outlet pipe, a flue gas outlet pipe and a desulfurization waste water spray pipe, an atomizing nozzle is arranged at the tail end of the desulfurization waste water spray pipe, negative pressure operation is performed in a drying tower body, and a primary air distribution plate and a secondary air distribution plate are arranged at the upper part in a straight cylinder body. The secondary air distribution plate is located below the primary air distribution plate, the atomizing nozzle is located below the secondary air distribution plate, the primary air distribution plate is a pore plate or a grating plate, the center of the secondary air distribution plate is a downstream air distribution area, the outer edge of the secondary air distribution plate is a rotating air distribution area, and an air direction isolation plate is arranged between the downstream air distribution area and the rotating air distribution area. The ventilation plane area ratio of the downstream air distribution area to the rotary air distribution area is 2: 1-3: 1, the downstream air distribution area is a pore plate or a grating plate, and the rotary air distribution area is an inclined guide plate. The drying tower can operate normally under the condition that the concentration of the atomized liquid is very low or ultrahigh, so that the adaptability of the drying tower is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of desulfurization wastewater resource treatment, and particularly relates to a desulfurization wastewater zero-discharge anti-wall-sticking drying tower. Background Art

[0002] Wastewater generated during coal-fired power plant operations has been significantly reduced through cascaded utilization. However, desulfurization wastewater generated during the desulfurization process is difficult to meet discharge standards no matter how it is treated. In recent years, new power plants have mandated zero wastewater discharge, while older plants have increasingly stringent emission standards. This has prompted both new and existing power plants to implement zero-discharge treatment for desulfurization wastewater, the most challenging wastewater to treat during power plant operations. In recent years, the "thermal" process, which uses high-temperature flue gas from power plants to evaporate and dry wastewater, has become the most widely used zero-discharge treatment method for desulfurization wastewater, gaining dominance due to its low investment.

[0003] Generally, before the wastewater enters the drying tower, it will be concentrated to the maximum reduction using a multi-effect evaporation process with low investment and operating costs. The salt and total solid content of the concentrate increase with the increase of the concentration ratio. However, for atomization drying, if the solid concentration in the wastewater is too high, the viscosity of the liquid will increase, the number of droplets sprayed from the nozzle per unit time will increase, the droplet movement speed will be low but the particle size will be large, and the water on the surface of the droplets will evaporate quickly to form a "hard shell" (there is still water inside). As the flue gas flows in the tower, the internal water of some large-particle droplets is not completely evaporated before they hit the wall of the drying tower. The collision will cause the particles to break, and a part of the broken part is very likely to adhere to the wall of the tube, causing "sticking to the wall". The other broken parts are completely dried with the flow of flue gas.

[0004] If the desulfurization wastewater is not concentrated, and other conditions such as flue gas temperature and flue gas volume, tower diameter and height remain unchanged, when spray drying is carried out directly at low concentration, the droplet movement speed is high, the particle size is small but the water content is high, and some high-speed moving small droplets will hit the wall of the drying tower before the water is completely evaporated. Unlike the ultra-high concentration liquid atomized particles, the small particles formed before the low concentration droplets are completely dried have no "hard shell" and will almost completely adhere to the wall of the tower. Therefore, low concentration liquid spray drying is more likely to cause "wall sticking" phenomenon.

[0005] When the "sticking to the wall" is serious, a thicker and thicker salt ash crystal layer will quickly form on the cylinder wall. When the weight of the crystal layer exceeds its adhesion or there is external force disturbance, it will fall off and fall into the ash hopper or silo pump at the bottom of the tower body, or even into the flue gas outlet, causing blockage of the ash hopper, silo pump and flue, affecting the normal operation of the drying tower, increasing the amount of maintenance, reducing production, increasing operating costs, and even affecting the operation of the main dust collector. Utility Model Content

[0006] In view of the above problems existing in the prior art, the utility model provides a desulfurization wastewater zero-discharge anti-wall-sticking drying tower.

[0007] The purpose of this utility model is achieved in the following ways:

[0008] A desulfurization wastewater zero-discharge anti-sticking wall drying tower, the drying tower body includes an upper cone, a straight cylinder and a lower cone, a flue gas inlet pipe is arranged at the top of the upper cone, an ash outlet pipe is arranged at the bottom of the lower cone, a desulfurization wastewater nozzle extending into the interior is arranged at the upper part of the straight cylinder, an atomizing nozzle is arranged at the end of the desulfurization wastewater nozzle, a flue gas outlet pipe is arranged at the lower part of the straight cylinder, the drying tower body operates under negative pressure, a primary air distribution plate and a secondary air distribution plate are arranged at the upper part of the straight cylinder, the secondary air distribution plate is located below the primary air distribution plate, and the atomizing nozzle is located below the primary air distribution plate. Below the secondary air distribution plate, the primary air distribution plate is a perforated plate or a grille plate, the center of the secondary air distribution plate is the downstream air distribution area, and the outer edge is the rotary air distribution area. A wind direction isolation plate is set between the downstream air distribution area and the rotary air distribution area. The ventilation plane area ratio of the downstream air distribution area to the rotary air distribution area is 2:1-3:1. The downstream air distribution area is a perforated plate or a grille plate, and the rotary air distribution area is an inclined guide plate. The pores on the primary air distribution plate and the secondary air distribution plate are evenly distributed, and the porosity is greater than 85%.

[0009] The included angle between the guide plate and the vertical direction is 30°-60°.

[0010] The primary air distribution plate is located in the straight cylinder 180-200mm below the upper cone.

[0011] The distance between the secondary air distribution plate and the primary air distribution plate is 380-400mm.

[0012] The number of atomizing nozzles is 1-4. When the number of atomizing nozzle is 1, it is located at the center of the plane of the drying tower body.

[0013] The vertical distance between the atomizing nozzle and the secondary air distribution plate is 200-300mm.

[0014] A wall-sticking purge pipe is also provided on the straight cylinder. The wall-sticking purge pipe is below the secondary air distribution plate, with a vertical distance of 6-7m from the secondary air distribution plate. The wall-sticking purge pipe enters the tower body along the tangent direction of the tower plane, and the dry ash discharged from the ash outlet pipe is introduced into the wall-sticking purge pipe.

[0015] There are two wall-sticking purge pipes, which are arranged on the straight cylinder at an interval of 180 degrees. The two wall-sticking purge pipes are arranged on the same horizontal plane or at different heights.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. The guide plate arranged obliquely on the secondary air distribution plate converts part of the high-temperature flue gas into a rotating downward air curtain area after passing through the secondary air distribution plate. A small part of the droplets that pass through the vertically downward downstream wind distribution area and move toward the wall of the drying tower enter this area and move in a rotating downward direction, extending the drying path of the droplets. The relatively small droplets that enter the rotating air curtain and the relatively large droplets at low speed will be completely dried before hitting the wall of the tower under the action of the rotating wind.

[0018] 2. The relatively high-speed mist droplets entering the rotating air curtain break through the rotating air curtain. Under the action of the rotating wind, they hit the inner wall of the tower in a nearly tangential direction. Due to the tangential "rolling" effect and the collision rebound effect, the mist droplets break into smaller particles or rebound or roll and enter the rotating air curtain again for bottom drying.

[0019] 3. A very small part of the droplets that collide with the inner wall of the tower will remain attached to the inner wall. However, the high-temperature flue gas entering the drying tower has a certain amount of dust. The dust particles in the flue gas, some particles that are completely dried in the rotating air curtain, and particles that enter the rotating air curtain after drying will have a sweeping, cleaning, and even "polishing" effect on the inner wall of the tower under the action of the rotating wind. The residues adhering to the inner wall of the tower will be swept away by the particles in the flue gas.

[0020] 4. Set up a wall-sticking purge pipe in the area of the drying tower where "sticking" is most likely to occur. Use the silo pump connected to the ash outlet pipe of the drying tower to pneumatically convey the dried ash into the wall-sticking purge pipe. The pipe opens in the tangential direction of the tower body, which is equivalent to adding additional incremental wind to the rotating wind curtain. First, it increases the rotating air volume in a short period of time, and second, it greatly increases the particle content of the rotating wind. This can effectively enhance the blowing effect of the rotating wind and completely remove the adherents on the cylinder wall.

[0021] 5. Regardless of whether the concentration of the liquid entering the atomizer is very low or very high, the drying tower can operate normally, improving the adaptability of the drying tower. Even if "sticking" occurs, it can be cleaned online using the sticking wall purge pipe without stopping the machine or entering the internal maintenance, without affecting normal operation and ensuring the continuity of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural diagram of the present utility model.

[0023] Figure 2 It is a schematic diagram of the internal structure of the utility model.

[0024] Figure 3 It is a schematic diagram of the secondary air distribution device and the wall-adhering purge pipe structure of the utility model.

[0025] Figure 4 It is a schematic diagram of the movement of smoke and atomized particles of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present invention.

[0027] like Figure 1-4 As shown, a desulfurization wastewater zero-discharge anti-sticking wall drying tower, the drying tower body 1 includes an upper cone, a straight cylinder and a lower cone, a flue gas inlet pipe 11 is provided at the top of the upper cone, and the high-temperature flue gas generated by the power plant is introduced into the flue gas inlet pipe 11, an ash outlet pipe 12 is provided at the bottom of the lower cone, a desulfurization wastewater nozzle 13 extending into the interior is provided at the upper part of the straight cylinder, an atomizing nozzle 131 is provided at the end of the desulfurization wastewater nozzle 13, a flue gas outlet pipe 14 is provided at the lower part of the straight cylinder, the drying tower body 1 operates under negative pressure, a primary air distribution plate 2 and a secondary air distribution plate 3 are provided at the upper part of the straight cylinder, the primary air distribution plate 2 is located 180-200 mm below the upper cone, and its outer diameter needs to ensure that it can be smoothly installed on the inner wall of the drying tower straight cylinder, the primary air distribution plate 2 is a perforated plate or a grille plate, the pores on the primary air distribution plate 2 are evenly distributed, and the porosity is greater than 8 5%; the secondary air distribution plate 3 is located below the primary air distribution plate 2, and the interval between the secondary air distribution plate 3 and the primary air distribution plate 2 is preferably 380-400mm, the atomizing nozzle 131 is located below the secondary air distribution plate 3, and the vertical spacing between the atomizing nozzle 131 and the secondary air distribution plate 3 is preferably 200-300mm, the center of the secondary air distribution plate 3 is the downstream wind distribution area, and the outer edge is the rotating wind distribution area. A wind direction isolation plate 31 is set between the downstream wind distribution area and the rotating wind distribution area. The ratio of the ventilation plane area of the downstream wind distribution area to the rotating wind distribution area is 2:1-3:1. The higher the dust content of the high-temperature flue gas, the larger the ventilation area of the downstream wind distribution area. The downstream wind distribution area is a perforated plate or a grille plate, and the rotating wind distribution area is an inclined guide plate 32. The pores on the secondary air distribution plate 3 are evenly distributed, and the porosity is greater than 85%.

[0028] The angle between the guide plate 32 and the vertical direction is preferably 30°-60°. The higher the dust content of the high-temperature flue gas, the larger the inclination angle. In addition, the number of guide plates is calculated by dividing the total area of the rotating air distribution area by the planar projection area of a single guide plate 32, and rounding the result.

[0029] The number of atomizing nozzles 131 is 1-4. When there is 1 atomizing nozzle 131, it is located at the center of the plane of the drying tower body 1. When there are 2-4 atomizing nozzles 131, its position needs to be calculated according to the atomizing radius of the atomizing nozzle.

[0030] The drying tower operates in a co-current manner, meaning the flue gas flows in the same direction as the atomized particles. After entering the tower through the flue gas inlet pipe 11 in the upper cone, the high-temperature flue gas experiences uneven flow velocity across the cross-section. However, after being redistributed by the primary air distribution plate 2, the flow velocity becomes relatively uniform across the tower. After passing through the secondary air distribution plate, approximately 2 / 3-3 / 4 of the flue gas maintains a vertical, co-current downward flow, forming a co-current wind zone. Another approximately 1 / 3-1 / 4 of the flue gas rotates downward at a certain angle along the tower's inner wall, forming a rotating wind curtain.

[0031] The droplets sprayed from the atomizing nozzle 131 move downward in a small-angle "umbrella bundle" shape, and exchange heat with the gas and dust particles in the high-temperature flue gas for evaporation and drying. According to the design, the atomized droplets should move vertically downward or downward at a very small deviation angle with the flue gas, and will be completely dried before reaching the flue gas outlet pipe. In reality, most droplets will move along the designed route, directly enter the flue gas outlet or fall into the lower cone after drying, or collide with the inner wall of the drying tower before entering the flue gas outlet or falling into the lower cone. However, due to some uncertain reasons or interference factors, or when the concentration of the liquid entering the atomization is very low or very high, a small number of droplets will break through the constraints of the "umbrella bundle" and move toward the wall of the drying tower through the vertically downward downstream wind area before being completely dried, and enter the downward rotating air curtain. The flue gas of the rotating air curtain moves obliquely downward. After entering this area, the droplets will move in the rotating downward direction, which is equivalent to extending the drying path of the droplets. The relatively small droplets entering the rotating air curtain and the relatively large droplets at low speed will be completely dried before hitting the wall of the drying tower under the action of the rotating wind. The relatively high-speed droplets entering the rotating air curtain may also break through the rotating air curtain and hit the inner wall of the tower before being completely dried. However, at this time, under the action of the rotating wind, the droplets hit the cylinder wall in a nearly tangential direction. Due to the tangential "rolling" effect and collision rebound effect, the droplets break into smaller particles or rebound or roll and enter the rotating air curtain again for complete drying.

[0032] A very small part of the droplets that collide with the rotating wind curtain and the inner wall of the tower body will remain and adhere to the inner wall, but the high-temperature flue gas entering the drying tower has a certain dust content. The dust particles in the flue gas, some particles that are completely dried in the rotating wind curtain, and particles that enter the rotating wind curtain after drying will have a blowing, cleaning and even "polishing" effect on the inner wall of the tower body under the action of the rotating wind. The residues adhering to the inner wall of the tower body will be swept away by the particles in the flue gas.

[0033] The evaporated moisture from the mist droplet drying enters the flue gas and is directed through the flue gas outlet pipe to the boiler's main flue dust collector. The dried mist droplets transform into crystallized salt ash particles, most of which (approximately 70-80%) are directed through flue gas outlet pipe 14 to the boiler's main flue dust collector. A small amount is discharged through the ash outlet pipe 12 and fed into the silo pump at the bottom of the drying tower, where it is then transported to the boiler's main flue or slag silo.

[0034] A further preferred solution is that a wall-sticking purge pipe 4 is further provided on the straight cylinder. The wall-sticking purge pipe 4 is below the secondary air distribution plate 3 and is vertically spaced 6-7m from the secondary air distribution plate 3 (the area where "wall sticking" is most likely to occur in the drying tower). The wall-sticking purge pipe 4 enters the tower body along the tangent direction of the tower body plane, and the dry ash discharged by the ash outlet pipe 12 is introduced into the wall-sticking purge pipe 4.

[0035] Furthermore, there are two wall-adhering purge pipes 4, which are arranged 180 degrees apart on the straight cylinder. The two wall-adhering purge pipes 4 are arranged at the same height on the same horizontal plane, or are staggered a certain distance up and down and arranged at different heights.

[0036] Two wall-sticking purge pipes are installed in the drying tower's most prone area to "sticking" to the wall. Using a silo pump connected to the drying tower's ash outlet pipe, the dried ash is pneumatically conveyed into the wall-sticking purge pipe's tangential openings. This effectively adds two streams of air to the rotating air curtain. This increases the rotating air volume in a short period of time and significantly increases the particulate matter content of the rotating air. This effectively strengthens the purge action of the rotating air, completely removing debris from the cylinder wall. The wall-sticking purge pipes operate for a short period of time, typically 1-3 minutes per cycle, and should be operated at least 1-2 times daily, depending on the drying tower's operating conditions.

[0037] Unless otherwise specified, the "wind" mentioned in the present invention refers to the high-temperature flue gas entering the tower body for drying.

[0038] The utility model is suitable for an airflow type atomizing drying tower.

[0039] The beneficial effects of the present invention are:

[0040] 1. The guide plate arranged obliquely on the secondary air distribution plate converts part of the high-temperature flue gas into a rotating downward air curtain area after passing through the secondary air distribution plate. A small part of the droplets that pass through the vertically downward downstream wind distribution area and move toward the wall of the drying tower enter this area and move in a rotating downward direction, extending the drying path of the droplets. The relatively small droplets that enter the rotating air curtain and the relatively large droplets at low speed will be completely dried before hitting the wall of the tower under the action of the rotating wind.

[0041] 2. The relatively high-speed mist droplets entering the rotating air curtain break through the rotating air curtain. Under the action of the rotating wind, they hit the inner wall of the tower in a nearly tangential direction. Due to the tangential "rolling" effect and the collision rebound effect, the mist droplets break into smaller particles or rebound or roll and enter the rotating air curtain again for thorough drying.

[0042] 3. A very small part of the droplets that collide with the inner wall of the tower will remain attached to the inner wall. However, the high-temperature flue gas entering the drying tower has a certain amount of dust. The dust particles in the flue gas, some particles that are completely dried in the rotating air curtain, and particles that enter the rotating air curtain after drying will have a sweeping, cleaning, and even "polishing" effect on the inner wall of the tower under the action of the rotating wind. The residues adhering to the inner wall of the tower will be swept away by the particles in the flue gas.

[0043] 4. Set up a wall-sticking purge pipe in the area of the drying tower where "sticking" is most likely to occur. Use the silo pump connected to the ash outlet pipe of the drying tower to pneumatically convey the dried ash into the wall-sticking purge pipe. The pipe opens in the tangential direction of the tower body, which is equivalent to adding additional incremental wind to the rotating wind curtain. First, it increases the rotating air volume in a short period of time, and second, it greatly increases the particle content of the rotating wind. This can effectively enhance the blowing effect of the rotating wind and completely remove the adherents on the cylinder wall.

[0044] 5. Regardless of whether the concentration of the liquid entering the atomizer is very low or very high, the drying tower can operate normally, improving the adaptability of the drying tower. Even if "sticking" occurs, it can be cleaned online using the sticking wall purge pipe without stopping the machine or entering the internal maintenance, without affecting normal operation and ensuring the continuity of equipment operation.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. A desulfurization wastewater zero-discharge anti-sticking drying tower, the drying tower body (1) comprising an upper cone, a straight cylinder and a lower cone, a flue gas inlet pipe (11) being provided at the top of the upper cone, an ash outlet pipe (12) being provided at the bottom of the lower cone, a desulfurization wastewater nozzle (13) extending into the interior being provided at the upper portion of the straight cylinder, an atomizing nozzle (131) being provided at the end of the desulfurization wastewater nozzle (13), and a flue gas outlet pipe (14) being provided at the lower portion of the straight cylinder, characterized in that: The drying tower body (1) operates under negative pressure. A primary air distribution plate (2) and a secondary air distribution plate (3) are provided in the upper part of the straight cylinder. The secondary air distribution plate (3) is located below the primary air distribution plate (2). The atomizing nozzle (131) is located below the secondary air distribution plate (3). The primary air distribution plate (2) is a perforated plate or a grille plate. The center of the secondary air distribution plate (3) is a downstream air distribution area, and the outer edge is a rotary air distribution area. A wind direction isolation plate (31) is provided between the downstream air distribution area and the rotary air distribution area. The ratio of the ventilation plane area of the downstream air distribution area to the rotary air distribution area is 2:1-3:

1. The downstream air distribution area is a perforated plate or a grille plate, and the rotary air distribution area is an inclined guide plate (32). The pores on the primary air distribution plate (2) and the secondary air distribution plate (3) are evenly distributed, and the porosity is greater than 85%.

2. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1, characterized in that: The included angle between the guide plate (32) and the vertical direction is 30°-60°.

3. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1, characterized in that: The primary air distribution plate (2) is located in the straight cylinder 180-200 mm below the upper cone.

4. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1 or 3, characterized in that: The secondary air distribution plate (3) and the primary air distribution plate (2) are spaced 380-400 mm apart.

5. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1, characterized in that: The number of the atomizing nozzles (131) is 1-4. When the number of the atomizing nozzle (131) is 1, it is located at the center of the plane of the drying tower body (1).

6. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1, characterized in that: The vertical distance between the atomizing nozzle (131) and the secondary air distribution plate (3) is 200-300 mm.

7. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 1, characterized in that: A wall-adhering purge pipe (4) is also provided on the straight cylinder. The wall-adhering purge pipe (4) is located below the secondary air distribution plate (3) and is vertically spaced 6-7 m from the secondary air distribution plate (3). The wall-adhering purge pipe (4) enters the tower body along a tangent direction of the tower body plane, and dry ash discharged from the ash outlet pipe (12) is introduced into the wall-adhering purge pipe (4).

8. The desulfurization wastewater zero-discharge anti-wall-sticking drying tower according to claim 7, characterized in that: There are two wall-adhering purge pipes (4), which are arranged on the straight cylinder at intervals of 180 degrees. The two wall-adhering purge pipes (4) are arranged on the same horizontal plane or at different heights.

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