CN108499228B - Multistage defroster - Google Patents

Abstract

The invention discloses a multistage demister. The demister comprises a plurality of demisting components, each demisting component comprises a gas lift pipe and an outer cylinder, the outer cylinder is arranged on the outer side of the gas lift pipe and is on the same axis with the gas lift pipe, and the inner surface of the outer cylinder is of a threaded structure; the riser is fixed on the tower tray, the top of the riser is provided with a sealing cover plate, the circumference of the riser is provided with a rectification channel, and the inner wall of the outer cylinder is provided with internal threads. The demister realizes the separation of liquid drops and gas through the rectification, acceleration and scraping effect of fluid in the flowing process. The demister disclosed by the invention is simple in structure, convenient to install and not easy to scale, and can effectively realize gas-liquid separation and reduce entrainment.

Description

Multistage defroster

Technical Field

The invention relates to gas-liquid separation equipment, in particular to a multistage demister.

Background

Large amount of SO is generated in the production process of industries such as electric power, metallurgy, petrochemical industry and the like₂And dust and other harmful substances, which bring serious acid rain hazard and haze weather, is the air pollutant which is currently controlled in China. At present, the wet desulphurization technology is generally adopted in the field of environmental protection to remove harmful substances such as sulfur dioxide in flue gas, namely, alkali liquor is sprayed on the flue gas to absorb or adsorb the harmful substances. However, in the wet desulfurization process, the flue gas desulfurized by the absorption tower contains a large amount of fine liquid drops with the particle size of about 10-60 microns, and sulfuric acid, sulfate and SO are dissolved in the liquid drops₂And the like, not only can cause pollution to the atmospheric environment, but also can cause serious corrosion and scaling to subsequent equipment. Thus, when using a wet desulfurization process, the cleaned gas must be demisted prior to exiting the absorber tower, and the demisting step is accomplished by means of a demister.

The defroster generally sets up at the absorption tower top, and when the gas that contains the mist passes through the defroster with certain speed, can collide with defroster inner structure to attach on its surface. Mist on the surface of the inner structure of the demister can be gradually gathered under the action of diffusion and gravity, and after the weight reaches a certain level, the mist can be separated from the inner structure of the demister, so that gas-liquid separation is realized. When the demister causes resistance drop to increase to a preset value due to scaling in the operation process, a backwashing program needs to be started to wash the demister, generally, washing nozzles need to be arranged at the air inlet end and the air exhaust end of the demister, and the gas phase can be seriously carried to the liquid phase to cause liquid entrainment of the gas phase.

Common demisters include a wire mesh demister, a herringbone plate demister, a spiral-flow plate demister and the like. Although the wire mesh demister can separate common mist, the mist is required to be clean, the flow velocity of air flow is small, resistance is reduced greatly, the service cycle is short, and the equipment investment is large. The current demister is generally arranged horizontally, the gas flowing direction of the demister is perpendicular to a wire mesh, when the gas velocity is low, entrained mist is small in inertia, the mist waves in the gas and cannot be removed due to collision contact with the wire mesh, and the gas is easy to generate secondary entrainment to the liquid drops due to the fact that separated liquid drops and the gas phase are in a countercurrent flow direction, so that the gas-liquid separation efficiency is reduced, and the wire mesh demister also has the problems of easy blockage, large pressure drop and the like. The blade type and herringbone demister are internally provided with baffle plates with different directions and different shapes so as to form a small flow channel, increase the demisting effect, and have more complex structure and poor separation effect. The whirl plate defroster is the same with the gaseous flow direction by the separation liquid drop, easily produces the secondary and smugglies secretly, reduces defogging efficiency to the pressure drop is big, and the energy consumption is higher.

The demisting element introduced in CN200410014713.X consists of a baffle plate and a flue gas flow field adjusting block, wherein the baffle plate is fixed on the flue gas flow field adjusting block, and the density and the shape of the baffle plate are changed according to the change of flow field parameters at each position of a flow section, so that the flow section of airflow in an absorption tower is uniformly distributed, and the phenomenon of gas-liquid countercurrent in the drop falling process can not be avoided, namely secondary entrainment is easy to generate.

The defroster that CN200920128824.1 introduced comprises cooler, thick defroster and smart defroster etc. and thick defroster is wave plate or defogging board, and smart defroster is the wire net, and this defroster has changed the shortcoming that traditional defroster liquid droplet flows against the current with the air current direction, has improved defogging efficiency. But this defroster structure is more complicated, and the preparation is difficult, owing to adopted the wire mesh structure, the defroster pressure drop is great, also blocks up relatively easily.

CN203724892U introduces a straight cylindric baffling formula defroster comprises a plurality of defogging subassembly, and every defogging subassembly all includes gas-lift pipe and urceolus, and the circumference of gas-lift pipe is opened has a plurality of seams, is provided with slot and tangential water conservancy diversion wing on the gas-lift pipe circumference that is close to each seam, and the tangential water conservancy diversion wing plays the water conservancy diversion effect, makes the gas flow direction change. The separation of liquid drops and gas is realized through multiple baffling of fluid in the flowing process, the liquid drops with smaller particle size can be effectively removed, and the demisting efficiency is higher. However, after the gas flows through the tangential flow guide wings, the gas direction is still relatively divergent and not concentrated enough, the gas speed is reduced, and the impact force is smaller when the gas collides with the inner wall of the outer barrel, so that the demisting effect is influenced. This defroster mainly relies on the baffling to make gaseous direction change, thereby gaseous and solid wall bumps and realizes gas-liquid separation, and is better to great liquid drop defogging effect, nevertheless is not obvious to the droplet effect, and this defroster structure is more complicated, and the easy scale deposit in space between gas-lift pipe and the tangential water conservancy diversion wing.

US7618472B2 provides a vane type demister comprised of corrugated plates, flat plates, louvers, etc. and defining a plurality of cavities or channels. After the gas-liquid mixture enters the demister, the fluid flow channel is deviated, so that the flow direction of the fluid can be changed for a plurality of times, the speed change is very fast, and the liquid phase is easily separated from the gas phase. In the process of separating the liquid phase from the gas phase, the gas-liquid cross flow can be realized, so that the secondary entrainment effect of the gas phase on liquid drops is greatly reduced, but the technology has a very complicated structure, high processing difficulty and high corresponding processing and manufacturing cost.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a multi-stage demister, which realizes the separation of liquid drops and gas through the rectification, acceleration and scraping effect of fluid in the flowing process. The demister disclosed by the invention has the advantages of simple structure, small pressure drop, difficulty in scaling and convenience in installation, reduces entrainment and can effectively realize gas-liquid separation.

The demister comprises a plurality of parallel demisting components, each demisting component comprises a gas lift pipe and an outer cylinder, the outer cylinder is arranged on the outer side of the gas lift pipe and preferably on the same axis with the gas lift pipe, and the inner surface of the outer cylinder is of a threaded structure; the gas lift pipe is fixed on the tower tray, and the top of the gas lift pipe is provided with a sealing cover plate; a plurality of rectifying channels are uniformly arranged on the circumference of the gas lift pipe, the rectifying channels are horizontally embedded along the tangential direction of the outer wall of the gas lift pipe, the side wall I of one side, close to the outer cylinder, of each rectifying channel is tangent to the wall of the gas lift pipe, the other side wall II of the rectifying channel is intersected with the wall of the gas lift pipe, and the rotating directions of the rectifying channels are the same; the top of the rectification channel is flush with the cover plate, and the bottom of the rectification channel is intersected with the tube wall of the gas lift tube.

In the demister, the thread structure on the inner surface of the outer cylinder adopts single threads or multiple threads, the number of the threads is n, n is more than or equal to 1, and n is preferably 1-3; the thread type adopts common threads, trapezoidal threads, sawtooth threads or circular arc threads, and the tooth form adopts triangle, trapezoid, sawtooth or arc (the thread refers to continuous protrusions with specified tooth form formed along a spiral line, and the protrusions refer to solid parts between two side surfaces of the thread and are also called teeth); the major diameter D of the internal thread is larger than the diameter D of the outer cylinder₂6-40 mm small and the pitch diameter D of the thread₂Smaller than the major diameter D of the thread by 1-20 mm and the minor diameter D of the thread₁Specific thread pitch diameter D₂1-20 mm small, 2-200 mm pitch P, large diameter D and medium diameter D of thread₂Minor diameter D₁The thread pitch P can refer to standard sizes corresponding to various threads, and can also be determined by a person skilled in the art according to actual working conditions or design requirements; the lead angle is also called lead angle, and refers to the included angle phi between the tangent of the helix on the pitch diameter cylinder and the plane perpendicular to the axis of the thread, tan phi is the ratio of lead to the circumference of the pitch diameter cylinder, i.e. phi = arctan (nP/Pi D)₂The lead of a single thread is equal to the pitch P, and the lead of a multiple thread is equal to the product of the pitch P and the number n of threads, the threadThe lead angle phi is not more than 60 degrees, preferably 1 to 20 degrees. The rotating direction of the thread structure is opposite to the rotating direction of the rectifying channel.

In the demister of the invention, the number of the rectifying channels is generally 1-12, preferably 4-8. The wall thickness of the rectifying channel is preferably the same as the wall thickness of the riser.

In the demister, the length l of the rectifying channel is the length of the side wall II, the width w is the maximum horizontal distance between the two side walls of the rectifying channel, and the height h is the maximum vertical distance between the top and the bottom of the rectifying channel; wherein the length l is 2-5 times, preferably 3-4 times of the width w; the cross section of the rectifying channel is in one or more combinations of rectangle, ellipse, circle, trapezoid or semicircle, and preferably in one or more combinations of rectangle, ellipse or circle. The size of the rectifying channel is determined by a person skilled in the art according to actual working conditions or design requirements, and if the height h of the rectifying channel is generally 20-600 mm, preferably 40-300 mm; the width w of the rectifying channel is generally 10-200 mm, preferably 20-100 mm. The total cross section area of the rectification channel is 0.2-0.9 times of the cross section area of the gas lift pipe, and preferably 0.3-0.6 times of the cross section area of the gas lift pipe.

In the demister, the tail end of the side wall II of the rectifying channel can be flush with the inner wall of the gas lift pipe or extend into the gas lift pipe for a certain distance m, wherein m is 0.1-0.9 times of the length l, and preferably 0.3-0.6 times. When the tail end of the side wall II of the rectifying channel is flush with the inner wall of the gas lift pipe, the tail end of the bottom of the rectifying channel is also flush with the inner wall of the gas lift pipe; when the side wall II of the rectifying channel extends into the interior of the gas lift pipe for a certain distance m, the tail end of the bottom of the rectifying channel is flush with the tail end of the side wall.

In the demister, the bottom of the rectifying channel is away from the tower tray by a certain distance A, and the distance A is 20-200 mm, preferably 40-80 mm.

In the demister, the lower end of the riser is flush with or lower than the tower tray by a certain distance, and the riser and the tower tray are hermetically connected; the diameter of the chimneys and the opening of the trays can be determined by one skilled in the art according to the actual operating conditions or design requirements.

In the demister, the rectifying channel, the cover plate and the gas rising pipe can be welded together or integrally formed.

In the demister of the invention, the outer cylinder is preferably a cylinder, and the diameter d2 of the outer cylinder is 1.5 to 6 times, preferably 2 to 3 times, the diameter d1 of the draft tube. The upper edge of the outer barrel is higher than the upper edge of the gas lift pipe by a certain distance C, and the distance C is 1-8 times, preferably 2-5 times, of the height h of the rectifying channel. The lower edge of the outer cylinder is away from the tower tray by a certain distance B and is lower than the lower edge of the rectifying channel, and the distance B between the lower edge of the outer cylinder and the tower tray is 5-100 mm, preferably 20-50 mm. The total height H of the outer barrel is 2.5-10 times, preferably 3-5 times of the height of the rectifying channel.

In the demisting device, the bottom of the gas lift pipe is provided with a lower sealing cover plate, the bottom of the gas lift pipe is lower than a tower tray by a certain distance, a plurality of gas inlet holes are uniformly formed on the circumference of the part below the tower tray of the gas lift pipe, and a gas inlet guide plate is arranged on the inner wall of the gas lift pipe at the gas inlet holes. The number of the air inlet holes is generally 3-12, preferably 6-10; the cross section of the air inlet hole is in one or more combinations of a rectangle, an ellipse, a circle, a trapezoid or a semicircle, and the like, and preferably in one or more combinations of a rectangle, an ellipse or a circle; the total sectional area of the air inlet holes is 0.6-1.5 times, preferably 0.8-1.2 times of that of the air lifting pipe, and the specific size is determined by a person skilled in the art according to the actual working condition or design requirement; the included angle between the tangent plane of the outer wall of the air lifting pipe, which is made by connecting the midpoints of the upper curve and the lower curve in the intersecting line of the air inlet hole and the outer wall of the air lifting pipe, and the plane of the air inlet flow guide plate close to one side of the air inlet hole is theta, wherein the theta is 10-60 degrees, and preferably 20-35 degrees. The air inlet guide plate is arranged at the edge of the air inlet hole along the axial direction of the air lifting pipe and is connected with the inner wall of the air lifting pipe through a connecting piece; the connecting piece constitute by baffle and pivot, baffle along gas-lift pipe axial and gas-lift pipe inner wall fixed connection, the guide plate that admits air is connected with the baffle through the pivot, the guide plate that admits air is the baffle position round pivot pivoted maximum angle. The rotating direction of each air inlet guide plate is the same as that of the blades, the shape of each air inlet guide plate can be one or combination of a plurality of rectangular, oval, circular, trapezoidal or semicircular shapes, the optimal shape is the same as that of the air inlet hole, and the sectional area of each air inlet guide plate is 1.1-2 times, 1.3-1.5 times that of the air inlet hole.

In the demister of the invention, the outer cylinder and the internal thread can be integrally formed or obtained by machining.

The connection parts of the components of the demister are sealed, and the phenomenon of air leakage is avoided.

When the demister works, gas carrying liquid drops enters the riser from the space at the lower part of the tray, a gas phase carrying liquid phase rises, the flow direction of the gas phase is changed after the gas phase carrying liquid phase meets the cover plate, namely the rising direction is changed into the horizontal direction or the direction approximate to the horizontal direction, part of small liquid drops collide with the cover plate due to the inertia effect and are attached to the cover plate, the attached liquid drops are gradually enlarged, and when the gravity generated by the liquid drops is larger than the resultant force of the rising force of the gas and the surface tension of the liquid, the liquid drops are separated from the surface of the cover plate, so that the first gas-liquid separation is completed; the gas carrying the liquid drops enters the rectifying channel along the horizontal direction or the approximate horizontal direction, because the rectifying channel has a certain length, and the total sectional area of the rectifying channel is smaller than the sectional area of the riser, the original gas carrying the liquid drops with a relatively dispersed speed direction is changed into the direction along the rectifying channel after entering the rectifying channel, the speed direction is relatively regular and concentrated, and because the flow area is reduced, the speed of the gas carrying the liquid drops is increased after entering the rectifying channel. When the speed direction of the gas carrying the liquid drops is changed, part of the liquid drops collide with the inner wall of the rectifying channel and are attached to the inner wall of the rectifying channel, and then the gas flowing through the rectifying channel continuously blows out of the rectifying channel and falls down to complete secondary gas-liquid separation. Meanwhile, in the rectifying channel, because the speed and direction of the gas carrying the liquid drops are changed, part of the small liquid drops collide with each other under the action of inertia force, the small liquid drops are gathered into large liquid drops, and the speed of the gas carrying the liquid drops flowing through the rectifying channel is increased, so that the movement of the liquid drops is intensified, the probability of the mutual collision of the small liquid drops is improved, the small liquid drops are more easily gathered into the large liquid drops and flow out of the rectifying channel along with the gas at a higher speed. The gas which flows out from the rectifying channel and is carried with the liquid drops has higher speed, the speed direction is more concentrated, the carried liquid drops are larger, the gas continuously collides with the inner wall of the outer barrel, and the flowing direction of the gas is changed again, namely the gas carried with the liquid drops flows along the circumferential direction of the inner wall of the outer barrel instead of the rectifying channel. Meanwhile, the spiral direction of the internal thread on the inner wall of the outer barrel is opposite to the rotation direction of the rectifying channel, namely the spiral direction of the internal thread is opposite to the flowing direction of the gas carrying liquid drops along the inner wall of the outer barrel, so that a relatively obvious scraping effect can be generated. The scraping effect means that when high-speed gas carrying liquid drops flows upwards along the inner wall of the outer barrel in a rotating mode, the liquid drops are thrown to the outer edge continuously under the action of inertia force, and large liquid drops carried in the gas are directly thrown to the tooth bottom of the inner thread and flow downwards along the thread line; the small liquid drops carried in the gas collide with the teeth of the internal thread and are attached to the teeth of the internal thread, and the internal thread greatly enlarges the collision surface between the gas carrying the liquid drops and the outer cylinder, so that the small liquid drops are continuously gathered and enlarged to form large liquid drops and then flow down along the thread line; because the tooth-shaped height of the internal thread is small, when the gas collides with the teeth of the internal thread, only the flow direction of the local gas is changed, and the overall flow trend of the gas is not influenced, so that the gas continuously keeps flowing upwards along the inner wall of the outer cylinder at a high speed, and the gas-liquid separation is realized for the third time. Through the rectification, acceleration and scraping effect, the liquid drops and the gas are separated in the flowing process of the fluid.

The demister is applied to an absorption tower adopting a wet desulphurization process, and generally the gas velocity entering a gas lift pipe is 3-20m/s, the gas velocity at the outlet of a rectifying channel is 10-40m/s, and the gas velocity at the outlet of the rectifying channel is 1.5-3 times of the gas velocity entering the gas lift pipe.

Compared with the prior art, the demister disclosed by the invention has the following advantages:

1. the rectifying channel has a certain length, the original speed direction of the gas with dispersed liquid drops is changed into the direction along the rectifying channel after entering the rectifying channel, and the speed direction is regular and concentrated; and the total sectional area of the rectifying channel is smaller than that of the riser, and the velocity of the gas carrying with liquid drops after entering the rectifying channel is increased due to the reduction of the flow area.

2. The inner wall of the outer barrel is provided with the internal thread, so that the contact area between the gas carrying the liquid drops and the inner wall of the outer barrel is increased, and the small liquid drops are favorably collected; the rotating direction of the internal thread is opposite to the flowing direction of the gas carrying the liquid drops along the inner wall of the outer barrel, so that the large liquid drops are directly thrown into the tooth bottoms of the internal threads and flow down along the thread line, the smaller liquid drops are attached to the teeth of the internal threads after being collided with the teeth of the internal threads, the small liquid drops are continuously gathered to form the large liquid drops and then flow down along the thread line, and the gas continuously keeps flowing upwards along the inner wall of the outer barrel at a high speed.

3. The lower end of the gas lift pipe is provided with a lower sealing cover plate, a plurality of gas inlet holes are uniformly formed in the circumferential direction of the lower end of the gas lift pipe, a plurality of gas inlet guide plates are arranged on the inner wall of the gas lift pipe at the gas inlet holes, so that gas enters the gas lift pipe along the horizontal direction, the gas flow direction is changed from the radial direction to the tangential direction when encountering the gas inlet guide plates, and the gas inlet guide plates can rotate, so that the gas inlet guide plates can automatically adjust the rotation angle of the gas inlet guide plates within a certain range according to the flow of the gas, and.

4. The demisting device can effectively achieve the demisting effect, effectively remove liquid drops with smaller particle sizes in gas, has high demisting efficiency, reduces harm to the environment, and plays a role in protecting the environment.

5. The gas flow is uniform, the flow resistance is small, and the resistance is reduced.

6. Simple structure, convenient manufacture, difficult blockage and scaling and no need of backwashing.

7. The water-saving effect is good, and the water removed from the gas carrying the liquid drops can be recycled, so that the water consumption is reduced.

Drawings

FIG. 1 is a schematic view of a demister of the present invention.

FIG. 2 is a schematic cross-sectional view of a rectification channel in a demister of the present invention.

FIG. 3 is a schematic cross-sectional view of another type of rectification channel in a demister of the present invention.

FIG. 4 is a schematic vertical cross-sectional view of a thread structure on the inner surface of the outer cylinder of the demister.

Fig. 5 is a schematic cross-sectional view of an air intake hole and an air intake baffle.

Each of the labels in the figure is: 1-a tray; 2-a riser; 3-rectifying the channel; 4-outer cylinder; 5-sealing the cover plate; 6-a thread structure; 7-air inlet holes; 8-a rotating shaft; 9-a baffle plate; 10-air inlet guide plate.

Detailed Description

The demister of the present invention will be described in further detail with reference to the accompanying drawings and examples.

The demister comprises a plurality of parallel demisting components, each demisting component comprises a gas riser 2 and an outer barrel 4, the outer barrel 4 is arranged on the outer side of the gas riser 2, preferably on the same axis with the gas riser 2, and the inner surface of the outer barrel 4 is of a threaded structure 6; the gas lift pipe 2 is fixed on the tray 1, and the top of the gas lift pipe 2 is provided with a sealing cover plate 5; a plurality of rectifying channels 3 are uniformly arranged on the circumference of the gas lift tube 2, the rectifying channels 3 are horizontally embedded along the tangential direction of the outer wall of the gas lift tube 2, the side wall I of one side, close to the outer cylinder 4, of each rectifying channel 3 is tangent to the tube wall of the gas lift tube 2, the other side wall II of the other side wall is intersected with the tube wall of the gas lift tube 2, and the rotating directions of the rectifying channels 3 are the same; the top of the rectifying channel 3 is flush with the sealing cover plate 5, and the bottom of the rectifying channel is intersected with the tube wall of the gas lift tube 2.

In the demister, the thread structure 6 on the inner surface of the outer cylinder 4 adopts single thread or multi-thread, the number of threads is n, n is more than or equal to 1, and n is preferably 1-3; the thread type adopts common threads, trapezoidal threads, sawtooth threads or circular arc threads, and the tooth form adopts triangle, trapezoid, sawtooth or arc (the thread refers to continuous protrusions with specified tooth form formed along a spiral line, and the protrusions refer to solid parts between two side surfaces of the thread and are also called teeth); the major diameter D of the internal thread is larger than the diameter D of the outer cylinder₂6-40 mm small and the pitch diameter D of the thread₂Smaller than the major diameter D of the thread by 1-20 mm and the minor diameter D of the thread₁Specific thread pitch diameter D₂1-20 mm small, 2-200 mm pitch P, large diameter D and medium diameter D of thread₂Minor diameter D₁The thread pitch P can refer to standard sizes corresponding to various threads, and can also be determined by a person skilled in the art according to actual working conditions or design requirements; the lead angle refers to the included angle phi between the tangent of the spiral line on the pitch diameter cylinder and the plane perpendicular to the thread axis,tan phi is the ratio of lead to mid-diameter cylinder circumference, i.e., phi = arctan (nP/. pi.D)₂The lead of the single thread is equal to the pitch P, the lead of the multiple thread is equal to the product of the pitch P and the number n of threads, and the lead angle phi is not more than 60 degrees, preferably 1 to 20 degrees. The rotating direction of the thread structure is opposite to the rotating direction of the rectifying channel.

In the demister of the invention, the rectifying channel 3 is generally provided with 1-12, preferably 4-8. The wall thickness of the rectifying channel 3 is preferably the same as the wall thickness of the riser 2.

In the demister, the length l of the rectifying channel 3 is the length of the side wall II, the width w is the maximum horizontal distance between the two side walls of the rectifying channel 3, and the height h is the maximum vertical distance between the top and the bottom of the rectifying channel 3; wherein the length l is 2-5 times, preferably 3-4 times of the width w; the cross section of the rectifying channel 3 is in one or more combinations of rectangle, ellipse, circle, trapezoid or semicircle, and preferably in one or more combinations of rectangle, ellipse or circle. The size of the rectifying channel 3 is determined by a person skilled in the art according to actual working conditions or design requirements, and if the height h of the rectifying channel 3 is generally 20-600 mm, preferably 40-300 mm; the width w of the rectifying channel 3 is generally 10 to 200mm, preferably 20 to 100 mm. The total cross-sectional area of the rectifying channel 3 is 0.2-0.9 times of the cross-sectional area of the gas-lifting tube 2, and preferably 0.3-0.6 times of the cross-sectional area of the gas-lifting tube 2.

In the demister, the tail end of the side wall II of the rectifying channel 3 can be flush with the inner wall of the gas lift pipe 2 or extend into the gas lift pipe 2 for a certain distance m, wherein m is 0.1-0.9 times of the length l, and preferably 0.3-0.6 times. When the tail end of the side wall II of the rectifying channel 3 is flush with the inner wall of the gas lift tube 2, the tail end of the bottom of the rectifying channel 3 is also flush with the inner wall of the gas lift tube 2; when the side wall II of the rectifying channel 3 extends into the interior of the gas lift tube 2 for a certain distance m, the tail end of the bottom of the rectifying channel 3 is flush with the tail end of the side wall.

In the demister, the bottom of the rectifying channel 3 is at a certain distance A from the tower tray 1, and the distance A is 20-200 mm, preferably 40-80 mm.

In the demister, the lower end of the riser 2 is flush with the tower tray 1 or is lower than the tower tray 1 by a certain distance, and the lower end of the riser and the tower tray are hermetically connected; the diameter of the riser 2 and the opening of the tray 1 can be determined by those skilled in the art according to the actual working conditions or design requirements.

In the demister of the invention, the rectifying channel 3, the cover plate 5 and the gas lift tube 2 can be welded together or integrally formed.

In the demister of the present invention, the outer cylinder 4 is preferably a cylinder, and the diameter d2 of the outer cylinder 4 is 1.5 to 6 times, preferably 2 to 3 times, the diameter d1 of the draft tube 2. The upper edge of the outer cylinder 4 is higher than the upper edge of the gas lift pipe 2 by a certain distance C, and the distance C is 1-8 times, preferably 2-5 times, of the height h of the rectifying channel 3. The lower edge of the outer cylinder 4 is away from the tower tray 1 by a certain distance B and is lower than the lower edge of the rectifying channel 3, and the distance B from the lower edge of the outer cylinder 4 to the tower tray 1 is 5-100 mm, preferably 20-50 mm. The total height H of the outer cylinder 4 is 2.5 to 10 times, preferably 3 to 5 times, the height of the rectifying channel 3.

In the defogging device, the bottom of the gas lift pipe is provided with a lower sealing cover plate, the bottom of the gas lift pipe is lower than a tower tray by a certain distance, a plurality of gas inlet holes 7 are uniformly formed on the circumference of the part below the tower tray of the gas lift pipe, and a gas inlet guide plate 10 is arranged on the inner wall of the gas lift pipe at the gas inlet holes. The number of the air inlet holes 7 is 3-12, preferably 6-10; the cross section of the air inlet 7 is in one or more combinations of rectangle, ellipse, circle, trapezoid or semicircle, and preferably in one or more combinations of rectangle, ellipse or circle; the total sectional area of the air inlet holes 7 is 0.6-1.5 times, preferably 0.8-1.2 times of that of the air lifting pipe, and the specific size is determined by a person skilled in the art according to the actual working condition or design requirement; the included angle between the tangent plane of the outer wall of the air lifting pipe, which is made by connecting the midpoints of the upper curve and the lower curve in the intersecting line of the air inlet hole and the outer wall of the air lifting pipe, and the plane of the air inlet flow guide plate close to one side of the air inlet hole is theta, wherein the theta is 10-60 degrees, and preferably 20-35 degrees. The air inlet guide plate 10 is arranged at the edge of the air inlet along the axial direction of the air lift pipe and is connected with the inner wall of the air lift pipe through a connecting piece; the connecting piece constitute by baffle 9 and pivot 8, baffle 9 along gas-lift pipe axial and gas-lift intraductal wall fixed connection, the guide plate 10 that admits air is connected with baffle 9 through pivot 8, the guide plate 10 that admits air is the baffle position round the pivot pivoted maximum angle. The rotating direction of each air inlet guide plate is the same as that of the blades, the shape of the air inlet guide plate 10 can be one or combination of a plurality of rectangular, oval, circular, trapezoidal or semicircular shapes, the preferred shape is the same as that of the air inlet hole, and the sectional area of the air inlet guide plate is 1.1-2 times, preferably 1.3-1.5 times that of the air inlet hole.

Example 1

The demister is applied to a certain wet washing tower for purifying flue gas, the diameter of an outer cylinder of a demisting component is 180mm, the diameter of a riser is 80mm, 4 rectifying channels are adopted, the length of each rectifying channel is 40mm, the width of each rectifying channel is 20mm, the height of each rectifying channel is 40mm, the tail end of a side wall II is flush with the inner wall of the riser, the distance A between the bottom of each rectifying channel and a tower tray is 30mm, the distance C from the upper edge of the outer cylinder to the upper edge of the riser is 200mm, the distance B from the lower edge of the outer cylinder to the tower tray is 20mm, and the total height H of the; the inner thread on the outer barrel adopts a single-line common thread, the major diameter D of the thread is 177mm, and the middle diameter D of the thread₂174mm, minor diameter D₁171mm, the pitch P8 mm and the lead angle phi of about 1 deg.. The apparent water concentration of the purified flue gas of a certain wet-type washing tower is 10-15 g/Nm³After demisting by the present invention, the concentration of the apparent water in the exhaust gas<0.5g/Nm³And the demisting efficiency is more than or equal to 95 percent.

Example 2

The demister is applied to a certain wet washing tower for purifying flue gas, the diameter of an outer cylinder of a demisting component is 180mm, the diameter of a riser is 80mm, 4 rectifying channels are adopted, the length of each rectifying channel is 40mm, the width of each rectifying channel is 20mm, the height of each rectifying channel is 40mm, the tail end of a side wall II is flush with the inner wall of the riser, the distance A between the bottom of each rectifying channel and a tower tray is 30mm, the distance C from the upper edge of the outer cylinder to the upper edge of the riser is 200mm, the distance B from the lower edge of the outer cylinder to the tower tray is 20mm, and the total height H of the; when the internal thread on the outer cylinder adopts a five-line trapezoidal thread, the major diameter D of the thread is 177mm, the middle diameter D2 of the thread is 166mm, the minor diameter D1 of the thread is 152mm, the thread pitch P of the thread is 28mm, and the lead angle phi of the thread is about 15 degrees. The apparent water concentration of the purified flue gas of a certain wet type washing tower is 12-16 g/Nm³After demisting by the present invention, the concentration of the apparent water in the exhaust gas<0.6g/Nm³And the demisting efficiency is more than or equal to 95 percent.

Claims (15)

1. A multistage mist eliminator, characterized in that: the demister comprises a plurality of parallel demisting components, each demisting component comprises a gas rising pipe and an outer cylinder, the outer cylinder is arranged on the outer side of the gas rising pipe, and the inner surface of the outer cylinder is of a threaded structure; the gas lift pipe is fixed on the tower tray, the top of the gas lift pipe is provided with a sealing cover plate, and the circumference of the gas lift pipe is uniformly provided with a plurality of rectifying channels; the rectifying channel is horizontally embedded along the tangential direction of the outer wall of the gas lift tube, the side wall I of the rectifying channel close to one side of the outer cylinder is tangent to the wall of the gas lift tube, the other side wall II of the rectifying channel is intersected with the wall of the gas lift tube, the top of the rectifying channel is flush with the cover plate, and the bottom of the rectifying channel is intersected with the wall of the gas lift tube; the rotation directions of all the rectification channels are the same; the pitch P of the thread structure is 2-200 mm; the rotating direction of the thread structure is opposite to the rotating direction of the rectifying channel; the bottom of the riser is provided with a lower sealing cover plate, the bottom of the riser is lower than the tower tray by a certain distance, a plurality of air inlet holes are uniformly formed on the circumference of the part below the tower tray of the riser, and an air inlet guide plate is arranged on the inner wall of the riser at the air inlet hole; the air inlet guide plate is arranged at the edge of the air inlet hole along the axial direction of the air lifting pipe and is connected with the inner wall of the air lifting pipe through a connecting piece; the connecting piece constitute by baffle and pivot, baffle along gas-lift pipe axial and gas-lift pipe inner wall fixed connection, the guide plate that admits air is connected with the baffle through the pivot, the guide plate that admits air is the baffle position round pivot pivoted maximum angle.

2. A demister as set forth in claim 1 wherein: the thread structure of the inner surface of the outer barrel adopts single thread or multi-thread, and the thread type adopts common thread, trapezoidal thread, sawtooth thread or circular arc thread.

3. A demister as set forth in claim 1 wherein: the major diameter D of the thread structure is larger than the diameter D of the outer cylinder₂6-40 mm small and the pitch diameter D of the thread₂Smaller than the major diameter D of the thread by 1-20 mm and the minor diameter D of the thread₁Specific thread pitch diameter D₂The size is 1-20 mm.

4. A demister as set forth in claim 1 or 2, wherein: the thread lead angle of the thread structure is 1-20 degrees.

5. A demister as set forth in claim 1 wherein: the number of the rectifying channels is 1-12.

6. A demister as set forth in claim 1 wherein: the length l of the rectifying channel is the length of the side wall II, the width w is the maximum horizontal distance between the two side walls of the rectifying channel, and the height h is the maximum vertical distance between the top and the bottom of the rectifying channel; wherein the length l is 2-5 times of the width w; the cross section of the rectifying channel is in one or a combination of a plurality of shapes of rectangle, ellipse, circle, trapezoid or semicircle.

7. A demister as set forth in claim 1 wherein: the total sectional area of the rectifying channel is 0.2-0.9 times of the sectional area of the gas lift pipe.

8. A demister as set forth in claim 1 wherein: the tail end of the side wall II of the rectifying channel is flush with the inner wall of the gas lift pipe or extends into the gas lift pipe for a certain distance m, wherein m is 0.1-0.9 time of the length l.

9. A demister as set forth in claim 8 wherein: when the tail end of the side wall II of the rectifying channel is flush with the inner wall of the gas lift pipe, the tail end of the bottom of the rectifying channel is also flush with the inner wall of the gas lift pipe; when the side wall II of the rectifying channel extends into the interior of the gas lift pipe for a certain distance m, the tail end of the bottom of the rectifying channel is flush with the tail end of the side wall.

10. A demister as set forth in claim 1 wherein: the bottom of the rectifying channel is away from the tower tray by a certain distance A, and the distance A is 20-200 mm.

11. A demister as set forth in claim 1 wherein: the outer cylinder is a cylinder, and the diameter D of the outer cylinder is 1.5-6 times of the diameter D of the riser; the upper edge of the outer cylinder is higher than the upper edge of the gas rising pipe by a certain distance P, and the distance P is 1-8 times of the height h of the rectifying channel; the lower edge of the outer cylinder is away from the tower tray by a certain distance B and is lower than the lower edge of the rectifying channel; the total height H of the outer barrel is 2.5-10 times of the height of the rectifying channel.

12. A demister as set forth in claim 1 wherein: 3-12 air inlets are arranged, and the cross section of each air inlet is in one or a combination of a plurality of rectangular, oval, circular, trapezoidal or semicircular shapes; the total sectional area of the air inlet holes is 0.6-1.5 times of the sectional area of the air lifting pipe.

13. A demister as set forth in claim 1 wherein: the included angle between the tangent plane of the outer wall of the air lifting pipe, which is made by connecting the midpoints of the upper curve and the lower curve in the intersecting line of the air inlet hole and the outer wall of the air lifting pipe, and the plane of the air inlet flow guide plate close to one side of the air inlet hole is theta, and the theta is 10-60 degrees.

14. A demister as set forth in claim 1 wherein: the rotating direction of each air inlet guide plate is the same as that of the blades, the shape of each air inlet guide plate is one or a combination of a plurality of rectangular, oval, round, trapezoidal or semicircular, and the sectional area of each air inlet guide plate is 1.1-2 times that of each air inlet hole.

15. Use of a demister as claimed in any one of claims 1-14 in an absorption tower of a wet desulphurization process, wherein: the gas velocity entering the gas lift pipe is 3-20m/s, the gas velocity at the outlet of the rectifying channel is 10-40m/s, and the gas velocity at the outlet of the rectifying channel is 1.5-3 times of the gas velocity entering the gas lift pipe.

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