阅读说明：本技术 一种用于溶剂萃取法净化湿法磷酸的石墨泡罩塔 (Graphite bubble column for purifying wet-process phosphoric acid by solvent extraction method ) 是由 孟海波 杨颖� 于 2020-11-12 设计创作，主要内容包括：本发明公开了一种用于溶剂萃取法净化湿法磷酸的石墨泡罩塔,包括有石墨塔体,石墨塔体内部由上至下水平设置有多层塔板,每层塔板边缘均活动竖向贯穿设置有1根降液管,降液管顶端与塔板表面存在间距,上、下两根降液管交错设置在上、下两层塔板的左、右两侧,石墨塔体内部左、右两侧边缘各设有1根连接轴,连接轴顶端均伸出至石墨塔体顶部,其伸出端设有齿条,齿条与齿轮啮合,齿轮与伺服电机连接,连接轴向下延伸穿入至同侧的降液管中并与之固定连接,每层塔板靠近上方降液管的一侧均设有1个下溢流堰,下溢流堰经下溢流堰打开装置与邻近的连接轴连接。该设备在不停车状态下实现了塔板排污放净和自动清洗功能,可保障泡罩塔常年不停车运转。(The invention discloses a graphite bubble tower for purifying wet-process phosphoric acid by a solvent extraction method, which comprises a graphite tower body, wherein a plurality of layers of tower plates are horizontally arranged in the graphite tower body from top to bottom, the edge of each layer of tower plate is movably and vertically penetrated with 1 downcomer, the top end of the downcomer is spaced from the surface of the tower plate, an upper downcomer and a lower downcomer are arranged on the left side and the right side of the upper layer of tower plate and the lower layer of tower plate in a staggered manner, the edges of the left side and the right side of the interior of the graphite tower body are respectively provided with 1 connecting shaft, the top end, the extending end of the tower plate is provided with a rack which is meshed with a gear, the gear is connected with a servo motor, a connecting shaft extends downwards to penetrate into the downcomer on the same side and is fixedly connected with the downcomer, one side of each layer of tower plate, which is close to the downcomer above, is provided with 1 underflow weir, and the underflow weirs are connected with the adjacent connecting shaft through an underflow weir opening device. The device realizes the functions of draining and cleaning the tower plate and automatically cleaning the tower plate under the non-stop state, and can ensure that the bubble cap tower runs without stopping all the year round.)

1. A graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method is characterized in that: comprises a graphite tower body (1), the top end of the graphite tower body (1) is provided with a gas material outlet (2), the bottom end is provided with a liquid material outlet (3), the side surface of the lower end of the graphite tower body (1) is provided with a material vapor-liquid mixture inlet (4), the gas material outlet (2) is connected with the material vapor-liquid mixture inlet (4) through a reboiler (6), a plurality of layers of tower plates (7) are horizontally arranged in the graphite tower body (1) from top to bottom, graphite bubble caps (8) are densely distributed on the surface of each layer of tower plate (7), a cleaning solution inlet (9) and a phosphoric acid raw material inlet (10) are vertically arranged on the graphite tower body (1) above the tower plate (7) at the topmost layer at intervals, the cleaning solution inlet (9) and the phosphoric acid raw material inlet (10) are respectively connected with 1 group of sprayers (11), the edge of each layer of, the top end of the downcomer (16) is spaced from the surface of the tower plate (7), the upper downcomer (16) and the lower downcomer (16) are arranged on the left side and the right side of the upper tower plate (7) and the lower tower plate (7) in a staggered mode, the edges of the left side and the right side of the interior of the graphite tower body (1) are respectively provided with 1 connecting shaft (12), the top end of each connecting shaft (12) extends out of the top of the graphite tower body (1), a rack (13) is arranged at the extending end of each connecting shaft, the rack (13) is meshed with a gear (14), the gear (14) is connected with a servo motor (15), the connecting shafts (12) extend downwards to penetrate into the downcomer (16) on the same side and are fixedly connected with the downcomer (16), one side, close to the downcomer (16) above, of each layer of tower plate (7) is provided with 1 underflow weir (19), and.

2. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the top end of the downcomer (16) is provided with an upper overflow weir which is of a vertical gullet structure, and the top end of the lower overflow weir (19) is also provided with a vertical gullet structure; the lower overflow weir opening device (20) comprises 1 vertical installation rod (21), the top of the vertical installation rod (21) is rotatably connected with 1 rotating rod (22), and two ends of the rotating rod (22) are respectively movably connected with the connecting shaft (12) and the lower overflow weir (19).

3. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 2, wherein: graphite bubble cap (8) include vertical pipeline (801) and cylindric housing (802), vertical setting of vertical pipeline (801) is on column plate (7) and its lower extreme runs through column plate (7), and it has a plurality of through-holes to open along vertical pipeline circumference equidistant on vertical pipeline (801) upper end lateral wall, cylindric housing (802) back-off is in vertical pipeline (801) upper end, and cylindric housing (802) downside edge is provided with vertical tooth's socket along its circumference equidistant, and the vertical tooth's socket bottom on last overflow weir and the underflow weir (19) on same column plate (7) is higher than the vertical tooth's socket top 15-30mm of cylindric housing (802) downside edge of graphite bubble cap (8).

4. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 3, wherein: the through hole on the side wall of the upper end of the vertical pipeline (801) is a waist-shaped hole arranged along the vertical direction; the vertical tooth grooves in the cylindrical housing (802) are vertical grooves formed in the vertical direction, and the upper ends of the vertical grooves are arcs arched upwards.

5. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the graphite tower body (1) lower extreme side still is equipped with tower bottom liquid export (17), and tower bottom liquid export (17) are connected with washing liquid circulating pump (18), and washing liquid circulating pump (18) are connected with washing liquid import (9) through the pipeline, are provided with automatic control pulse valve (23) on the pipeline between washing liquid circulating pump (18) and washing liquid import (9), and automatic control pulse valve (23) are connected with servo motor (15).

6. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the cleaning liquid inlet (9) is positioned above the phosphoric acid raw material inlet (10), and a demister (24) is arranged inside the graphite tower body (1) between the cleaning liquid inlet and the phosphoric acid raw material inlet.

7. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the connecting shaft (12) and the downcomer (16) penetrate through the tower plate (7) and are connected with the tower plate in a sliding and sealing manner, and the sliding and sealing connection structure is a double-O-shaped-ring piston sealing structure; the interior of the downcomer (16) is fixedly connected with the connecting shaft (12) through a connecting frame (29).

8. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the graphite tower body (1) is formed by coaxially stacking a plurality of graphite tower sections (25) from bottom to top, the graphite tower sections (25) are of cylindrical annular structures, the outer surfaces of the graphite tower sections (25) are regular polygons, the inner surfaces of the graphite tower sections are cylindrical, the graphite tower sections (25) are of annular splicing structures formed by graphite blocks (26), the splicing forms are tongue-and-groove type splicing seam structures, and carbon fiber resin composite materials are wound outside each graphite tower section (25); the upper graphite tower section (25) and the lower graphite tower section (25) are connected in a pressing and sealing manner by gaskets.

9. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the liquid material outlet (3) is provided with a filter (27) at the upper part, the bottom of the graphite tower body (1) is of a conical structure, and a metal conical clamp (28) is arranged outside the conical structure.

10. The graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method as claimed in claim 1, wherein: the gas material outlet (2) is connected with a vortex separator (5) through a pipeline, the vortex separator (5) is connected with a reboiler (6), and a material gas-liquid mixture inlet (4) at the other end of the reboiler (6) is connected.

Technical Field

The invention relates to a graphite bubble tower for purifying wet-process phosphoric acid by a solvent extraction method, belonging to the technical field of chemical equipment.

Background

Wet process phosphoric acid is less expensive to produce, but has a higher impurity content, and therefore requires purification. The purification of wet-process phosphoric acid comprises two aspects: (1) removing sludge generated in the wet-process phosphoric acid; (2) removing dissolved in phosphoric acid: fluorine, sulfate, iron, aluminum, magnesium, silicon, calcium, arsenic, lead, cadmium, and the like. The purification process of the wet-process phosphoric acid comprises the following steps: organic solvent extraction, chemical precipitation, ion exchange, physical adsorption, crystallization, and the like. Wherein, the solvent extraction method is advanced, in particular to a process method for preparing food-grade phosphoric acid by using MIBK as an extracting agent represented by Albright & Wilson company; the solvent is easy to recover, and the extraction rate is high; industrial applications have been widely realized.

The production process of the wet-process phosphoric acid purified by the solvent extraction method comprises the following steps: pretreatment → defluorination → extraction → washing → back extraction → post-treatment. When the wet-process phosphoric acid is purified by an extraction method, the crude phosphoric acid is pretreated to remove impurities such as sulfate radicals, fluorides, heavy metals and the like, then an organic extractant is added for extraction, most of cations in the phosphoric acid can be removed, and desalted water is used for back extraction of the phosphoric acid in an organic phase, so that the purified phosphoric acid is obtained. The wet-process phosphoric acid has high fluorine content, and fluorine in the phosphoric acid needs to be removed through a defluorination process, and the existing defluorination technology mainly adopts a graphite bubble tower for gas stripping defluorination. The traditional graphite bubble-cap tower has poor structural strength, higher production energy consumption and low production efficiency. Solid impurities and sludge are deposited on the graphite tower plate under the steady flow effect of the overflow weir, and after a period of time, the settled matters block bubble caps, so that the bubble cap tower cannot work normally. On average, the tower needs to be disassembled and manually cleaned once every 2 months, so that the stability of process operation is damaged, the operation and maintenance cost is increased, the graphite tower is easily damaged when the tower is started and stopped, and the production cost and the safety risk are increased.

Disclosure of Invention

The invention aims to provide a graphite bubble column for purifying wet-process phosphoric acid by a solvent extraction method. The device realizes the functions of draining and cleaning the tower plate and automatically cleaning the tower plate under the non-stop state, and can ensure that the bubble cap tower runs without stopping all the year round. The graphite bubble-cap tower has high structural strength, increases the effective area of gas-liquid mass transfer of the graphite tower plate, improves the mass transfer efficiency, saves energy, has small phosphoric acid loss and good defluorination effect; the automation degree is high.

The technical scheme of the invention is as follows: a graphite bubble tower for purifying wet-process phosphoric acid by a solvent extraction method comprises a graphite tower body, wherein the top end of the graphite tower body is a gas material outlet, the bottom end of the graphite tower body is a liquid material outlet, the side surface of the lower end of the graphite tower body is provided with a material vapor-liquid mixture inlet, the gas material outlet and the material vapor-liquid mixture inlet are connected through a reboiler, a plurality of layers of tower plates are horizontally arranged in the graphite tower body from top to bottom, graphite bubble caps are densely distributed on the surface of each layer of tower plate, a cleaning liquid inlet and a phosphoric acid raw material inlet are vertically arranged on the graphite tower body above the topmost tower plate at intervals, the cleaning liquid inlet and the phosphoric acid raw material inlet are respectively connected with 1 group of sprayers, the edge of each layer of tower plate is movably and vertically provided with 1 downcomer in a penetrating manner, the top end of each, the edge of the left side and the edge of the right side of the interior of the graphite tower body are respectively provided with 1 connecting shaft, the top end of each connecting shaft extends out of the top of the graphite tower body, the extending end of each connecting shaft is provided with a rack which is meshed with a gear, the gear is connected with a servo motor, the connecting shafts extend downwards to penetrate into the downspouts on the same side and are fixedly connected with the downspouts, one side of each layer of tower plate close to the downspouts on the same side is provided with 1 underflow weir, and the underflow weirs are connected with the adjacent connecting shafts.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the top end of the downcomer is an upper overflow weir, the upper overflow weir is of a vertical gullet structure, and the top end of the lower overflow weir is also provided with a vertical gullet structure; the lower overflow weir opening device comprises 1 vertical installation rod, the top of the vertical installation rod is rotatably connected with 1 rotating rod, and two ends of the rotating rod are respectively movably connected with the connecting shaft and the lower overflow weir.

In the graphite bubble cap tower for purifying wet-process phosphoric acid by using the solvent extraction method, the graphite bubble cap comprises a vertical pipeline and a cylindrical cover shell, the vertical pipeline is vertically arranged on the tower plate, the lower end of the vertical pipeline penetrates through the tower plate, a plurality of through holes are formed in the side wall of the upper end of the vertical pipeline at equal intervals along the circumferential direction of the vertical pipeline, the cylindrical cover shell is reversely buckled at the upper end of the vertical pipeline, vertical tooth grooves are formed in the lower side edge of the cylindrical cover shell at equal intervals along the circumferential direction of the cylindrical cover shell, and the bottoms of the vertical tooth grooves in an upper overflow weir and a lower overflow weir on the same tower plate are 15-30.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the through hole in the side wall of the upper end of the vertical pipeline is a waist-shaped hole arranged along the vertical direction; the vertical tooth grooves on the cylindrical housing are vertical channels which are arranged along the vertical direction, and the upper ends of the vertical channels are arcs which are arched upwards.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the side surface of the lower end of the graphite column body is also provided with a column bottom liquid outlet, the column bottom liquid outlet is connected with a cleaning liquid circulating pump, the cleaning liquid circulating pump is connected with a cleaning liquid inlet through a pipeline, an automatic control pulse valve is arranged on the pipeline between the cleaning liquid circulating pump and the cleaning liquid inlet, and the automatic control pulse valve is connected with a servo motor.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the cleaning liquid inlet is positioned above the phosphoric acid raw material inlet, and a demister is arranged in the graphite column body between the cleaning liquid inlet and the phosphoric acid raw material inlet.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the connecting shaft and the downcomer penetrate through the tower plate and are connected with the tower plate in a sliding and sealing manner, and the sliding and sealing connection structure is a double-O-shaped ring piston sealing structure; the interior of the downcomer is fixedly connected with the connecting shaft through the connecting frame.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the graphite column body is formed by coaxially stacking a plurality of graphite tower sections from bottom to top, the graphite tower sections are in cylindrical annular structures, the outer surfaces of the graphite tower sections are in regular polygons, the inner surfaces of the graphite tower sections are in cylindrical shapes, the graphite tower sections are in annular graphite block splicing structures in a tongue-and-groove type splicing seam structure, and carbon fiber resin composite materials are wound outside each graphite tower section; the upper graphite tower section and the lower graphite tower section are connected in a pressing and sealing mode through gaskets.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the filter is arranged at the upper part of the liquid material outlet, the bottom of the graphite column body is of a conical structure, and the metal conical clamp is arranged outside the conical structure.

In the graphite bubble column for purifying wet-process phosphoric acid by using the solvent extraction method, the gas material outlet is connected with the vortex separator through a pipeline, the vortex separator is connected with the reboiler, and the material gas-liquid mixture inlet at the other end of the reboiler is connected.

The invention has the beneficial effects that: compared with the prior art, the invention has the following advantages:

1. the automatic control overflow weir lifting mechanism is formed by arranging the cleaning fluid inlet, the sprayer, the connecting shaft, the downcomer and the underflow weir, wherein a rack on the connecting shaft is meshed with a gear, the gear is connected with a servo motor, and the connecting shaft is fixedly connected with the downcomer, so that the automatic blowdown and emptying functions of the tower plate are realized.

2. Overflow weirs on odd-numbered tower plates and even-numbered tower plates can realize automatic control of gradual lifting and washing respectively; the total amount of liquid flow and air flow of the bubble-cap tower is ensured to be stable, and the material flow state of the bubble-cap tower is not damaged; the normal working state can be recovered within 10 minutes after cleaning.

3. The tower bottom liquid outlet is connected with the cleaning liquid inlet through a cleaning liquid circulating pump, and the tower bottom liquid is used as a tower plate cleaning liquid, so that the physical property data of gas and liquid discharged out of the tower are not over standard in a non-stop state.

4. Be provided with the automatic control pulse valve on the pipeline, the automatic control pulse valve is connected with servo motor for the action of spraying of washing liquid and the descending action cooperation of downcomer are accurate, and is efficient, and operating error is little, and degree of automation is high.

5. The device can realize the automatic control of the complete device for cleaning the tower plate under the state of no stopping. The bubble cap tower is cleaned once a day in operation, each cleaning time is 2 minutes, and the bubble cap tower can be ensured to run without stopping all the year round. Compared with the traditional process, the manual cleaning for disassembling the tower is carried out once every 2 months, so that the operation and maintenance cost is greatly saved, the stability of the process operation is ensured, the starting efficiency is improved, and the high-frequency risk that the graphite equipment is easily damaged and broken down when the vehicle is started and stopped is reduced.

6. The downcomer and the upper overflow weir are integrally formed, the structure is compact and reasonable, the working efficiency is high, the space of the column plate is saved, more bubble caps can be arranged, and the utilization rate of the column plate is improved.

7. The integrally processed bubble cap made of graphite has the advantages of large specific surface area, good gas-liquid exchange, high working efficiency and difficult scaling.

8. The outer surface of the graphite tower section is designed into a polygonal columnar body, which is equivalent to that the tower body is longitudinally provided with a reinforcing rib; good strength, high stability and beautiful appearance.

9. The graphite tower section adopts a graphite block annular splicing structure, the splicing form is a tongue-and-groove type splicing seam, the strength is good, the anti-permeability is good, and the performance is stable and reliable.

10. The carbon fiber resin composite material is wound outside the tower section, so that circumferential reinforcement can be realized, and the pressure resistance is strong.

11. The lower end socket of the graphite tower body has the largest pressure bearing, so that a special conical steel holding structure is adopted, the reinforcing effect is good, and the performance is stable and reliable.

12. The bottom of the tower is provided with a vortex separator for settling solids and realizing non-stop pollution discharge.

In summary, the device provided by the invention overcomes the problems of low impurity removal rate, high production cost and the like of the existing production device, reduces the production cost of food-grade phosphoric acid, realizes the functions of draining and discharging the tower plate and automatically cleaning under the non-stop state, can ensure that the bubble cap tower runs without stopping for a long time, realizes the efficient utilization of the graphite bubble cap tower, and improves the economic benefit of wet-process phosphoric acid.

Drawings

FIG. 1 is a schematic structural diagram of the present invention;

FIG. 2 is an enlarged top view of FIG. 1;

FIG. 3 is an enlarged, schematic view of the lower portion of FIG. 1;

FIG. 4 is a schematic structural view of a graphite tower section;

FIG. 5 is a schematic top view of the structure of FIG. 2;

FIG. 6 is a schematic diagram of the structure of a graphite block;

FIG. 7 is a schematic diagram of a bonding seam structure of adjacent graphite blocks;

FIG. 8 is a schematic view of the connection structure of the downcomer and the tray;

FIG. 9 is a schematic view showing a connecting structure of a connecting shaft and a tray;

FIG. 10 is a schematic illustration of the construction of an underflow weir;

FIG. 11 is a schematic diagram of the distribution of the sprinklers;

FIG. 12 is a schematic view showing the construction of an underflow weir opening device;

fig. 13 is a schematic view of a connection structure of the connection shaft and the gear.

Reference numerals: 1-a graphite tower body, 2-a gas material outlet, 3-a liquid material outlet, 4-a material vapor-liquid mixture inlet, 5-a vortex separator, 6-a reboiler, 7-a tower plate, 8-a graphite bubble cap, 801-a vertical pipeline, 802-a cylindrical housing, 9-a cleaning liquid inlet, 10-a phosphoric acid raw material inlet, 11-a sprayer, 12-a connecting shaft, 13-a rack, 14-a gear, 15-a servo motor, 16-a downcomer, 17-a tower bottom liquid outlet, 18-a cleaning liquid circulating pump, 19-an underflow weir, 20-an overflow weir opening device, 21-a vertical mounting rod, 22-a rotating rod, 23-an automatic control pulse valve, 24-a demister, 25-a graphite tower section and 26-a graphite block, 27-filter, 28-metal conical clamp, 29-connecting frame and 30-downcomer water seal cap.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

The embodiment of the invention comprises the following steps: a graphite bubble tower for purifying wet-process phosphoric acid by a solvent extraction method is disclosed, as shown in attached figures 1-13, and comprises a graphite tower body 1, wherein the top end of the graphite tower body 1 is provided with a gas material outlet 2, the bottom end of the graphite tower body is provided with a liquid material outlet 3, the side surface of the lower end of the graphite tower body 1 is respectively provided with a material vapor-liquid mixture inlet 4, the gas material outlet 2 is connected with the material vapor-liquid mixture inlet 4 through a reboiler 6, a plurality of layers of tower plates 7 are uniformly and horizontally arranged in the graphite tower body 1 from top to bottom at intervals, graphite bubble caps 8 are densely distributed on the surface of each layer of tower plate 7, a plurality of cleaning solution inlets 9 and a plurality of phosphoric acid raw material inlets 10 are vertically arranged on the graphite tower body 1 above the tower plate 7 at the topmost layer at intervals, each cleaning solution inlet 9 and each phosphoric acid raw material inlet 10 are, the top end of a downcomer 16 is spaced from the surface of a tower plate 7, an upper downcomer 16 and a lower downcomer 16 are arranged at the edge positions of the left side and the right side of the upper tower plate 7 and the lower tower plate 7 in a staggered mode, 1 connecting shaft 12 is arranged at the edge position of the left side and the edge position of the right side of the inner portion of the graphite tower body 1, the top end of each connecting shaft 12 extends out of the top of the graphite tower body 1, a vertical rack 13 is arranged at the extending end of each connecting shaft, the racks 13 are meshed with gears 14, the gears 14 are connected with servo motors 15, the connecting shafts 12 extend downwards to penetrate into the downcomers 16 at the same side and are fixedly connected with the downcomers 16, the tail end of each downcomer 16 on the bottom tower plate 7 is connected with 1 downcomer water sealing cap 30, one side, close to the downcomer 16 above each layer of tower plate 7, the bottom of each downcomer 19 is in contact with the.

In the using process, the fluorine-containing phosphoric acid is sent into the graphite tower body 1 from the phosphoric acid raw material inlet 10, is sprayed out by the sprayer 11 connected with the phosphoric acid raw material inlet, is uniformly distributed along the tower plate 7, overflows downwards through the downcomer 16 and finally deposits to the bottom of the graphite tower body 1. The deposited liquid raw material is circulated to a reboiler 6 through a pipeline for heating, a material gas-liquid mixture generated by the reboiler 6 enters the tower bottom through a material gas-liquid mixture inlet 4, the heated liquid gas-liquid is separated, steam rises from the tower bottom and is discharged through a graphite bubble cap 8, meanwhile, the fluorine-containing phosphoric acid on the tower plate 7 cannot be discharged downwards through the graphite bubble cap 8, the fluorine-containing phosphoric acid on the tower plate 7 is in countercurrent contact with the steam, mass and heat transfer is realized, fluoride in the fluorine-containing phosphoric acid is stripped out in the process and enters a gas phase, the gas phase drifts upwards and is finally discharged through a gas material outlet 2 at the top of the graphite tower body 1, and defluorinated phosphoric acid is obtained at the. Downcomer water caps 30 on the bottommost downcomer 16 prevent the steam generated after heating from being discharged therefrom to the upper tray 7.

After a certain time of defluorination, sludge is deposited on the surface of the tower plate 7, so that the sludge needs to be discharged and removed. During pollution discharge and silt removal, cleaning liquid is fed into the graphite tower body 1 from the cleaning liquid inlet 9 and is sprayed out through the sprayer 11 connected with the graphite tower body, and the sprayed cleaning liquid washes silt on the tower plate 7 layer by layer from top to bottom. Meanwhile, the servo motor 15 is started to drive the gear 14 to rotate, the gear 14 drives the connecting shaft 12 to move downwards in the meshing process with the rack 13, the connecting shaft 12 can drive the downcomer 16 connected with the connecting shaft to descend, and the top of the downcomer 16 descends to a position 10mm away from the upper surface of the tower plate 7 to be used as a sewage discharge pipe of the tower plate to discharge deposited sludge, so that the function of draining and cleaning sewage from the tower plate 7 is realized. The connecting shaft 12 simultaneously drives the lower overflow weir 19 to lift upwards through the lower overflow weir opening device 20, and the sludge of the tower plate 7 surrounded by the lower overflow weir 19 is discharged completely. After the sewage draining operation is finished, the servo motor 15 acts in a reverse direction, so that the downcomer 16 and the lower overflow weir 19 are restored to the initial positions.

In the process of draining and dredging the tower plates 7, the connecting shafts 12 on the odd-numbered tower plates 7 and the even-numbered tower plates 7 are gradually lifted, so that the respective washing is realized, the total amount of liquid flow and air flow of the bubble-cap tower is ensured to be stable, the material flow state of the tower is not damaged, and the normal working state can be recovered within 10 minutes after the washing.

The washing can be automatically controlled without stopping in the whole process, the washing is carried out once every day for 2 minutes every time, and the bubble cap tower can be guaranteed to run without stopping all the year round. Compared with the traditional process, the tower dismantling device is shut down every 2 months and manually cleaned, so that the operation and maintenance cost is greatly saved, the stability of process operation is ensured, the starting efficiency is improved, and the high-frequency risk that the graphite equipment is damaged and fails due to starting and stopping is reduced.

The graphite bubble column for purifying wet-process phosphoric acid by the solvent extraction method is stripped and defluorinated to prepare food-grade phosphoric acid, the suitable vacuum degree is 65-70 KPa, the stripping time is 1.5h, the fluorine content in acid tends to be stable, and the fluorine content in the product acid after stripping is reduced to below 10mg/L, thereby reaching the national standard of food-grade phosphoric acid. The defluorination efficiency in the stripping process is hardly affected by the concentration of the raw material phosphoric acid. The stripping operation saves most energy and time when the concentration of the raw material phosphoric acid is 52 percent. After stripping for 15h under vacuum degree, the phosphorus loss is below 0.6 percent and can be almost ignored.

The top end of the downcomer 16 is provided with an upper overflow weir which is of a vertical gullet structure, and the top end of the lower overflow weir 19 is also provided with a vertical gullet structure. The surging phenomenon can appear in the liquid material top-down flow in-process, and be provided with vertical tooth's socket structure, can make liquid material keep flowing steadily on the column plate. An upper overflow weir and a downcomer 16 which are respectively arranged on the right side of the odd-numbered tower plates 7 and the left side of the even-numbered tower plates 7; the upper overflow weir and the downcomer 16 are of an integrally formed structure, the structure is compact and reasonable, the working efficiency is high, and the space of the tower plate 7 can be saved, so that the arrangement number of the graphite bubble caps 8 is increased, and the utilization rate of the tower plate 7 is improved.

The lower overflow weir opening device 20 comprises 1 vertical installation rod 21, the top of the vertical installation rod 21 is rotatably connected with 1 rotating rod 22, and two ends of the rotating rod 22 are respectively movably connected with the connecting shaft 12 and the lower overflow weir 19. The connecting shaft 12, the lower overflow weir 19, the vertical mounting rod 21 and the rotating rod 22 form 1 seesaw structure, when the connecting shaft 12 goes down, the rotating rod 22 which is movably connected with the connecting shaft is driven to rotate around the movable connecting end of the rotating rod 22 and the vertical mounting rod 21, the connecting end of the rotating rod 22 and the lower overflow weir 19 is lifted upwards, so that the lower overflow weir 19 is lifted upwards synchronously, and partial sludge of the tower plate 7 surrounded by the lower overflow weir 19 is washed clean by cleaning liquid.

A plurality of graphite bubble caps 8 are distributed on the rest positions of the whole tower plate 7 according to a regular triangle. The graphite bubble cap 8 comprises a vertical pipeline 801 and a cylindrical cover shell 802, the vertical pipeline 801 is vertically arranged on the tower plate 7, the lower end of the vertical pipeline penetrates through the tower plate 7, a plurality of through holes are formed in the side wall of the upper end of the vertical pipeline 801 at equal intervals along the circumferential direction of the vertical pipeline, the cylindrical cover shell 802 is buckled on the upper end of the vertical pipeline 801 in an inverted mode, vertical tooth grooves are formed in the lower side edge of the cylindrical cover shell 802 at equal intervals along the circumferential direction of the cylindrical cover shell 802, and the bottoms of the vertical tooth grooves in an upper overflow weir and a lower overflow weir 19 on the same tower plate 7 are 15-30mm higher than. The through hole on the side wall of the upper end of the vertical pipeline 801 is a waist-shaped hole arranged along the vertical direction; the vertical tooth grooves on the cylindrical housing 802 are vertical channels formed in the vertical direction, and the upper ends of the vertical channels are arcs arched upwards. Graphite bubble cap 8 forms for whole processing, and above structure can make graphite bubble cap 8's specific surface area increase, improves the gas-liquid exchange effect, and work efficiency is better, is difficult for the scale deposit moreover.

The side surface of the lower end of the graphite tower body 1 is also provided with a tower bottom liquid outlet 17, the tower bottom liquid outlet 17 is positioned below the material vapor-liquid mixture inlet 4, the tower bottom liquid outlet 17 is connected with a cleaning liquid circulating pump 18, the cleaning liquid circulating pump 18 is connected with a cleaning liquid inlet 9 through a pipeline, an automatic control pulse valve 23 is arranged on the pipeline between the cleaning liquid circulating pump 18 and the cleaning liquid inlet 9, and the automatic control pulse valve 23 is connected with the servo motor 15. In the sewage disposal process, tower bottom liquid can be used as cleaning liquid, and after being discharged from a tower bottom liquid outlet 17, the tower bottom liquid is pumped to a cleaning liquid inlet 9 through a cleaning liquid circulating pump 18 and is finally sprayed out from a sprayer 11 connected with the cleaning liquid inlet 9, so that sewage disposal and desilting are realized. When the automatic control impulse valve 23 senses a flow of liquid in the pipe, a control signal is sent out, so that the servo motor 15 starts to start. The synchronous control of the cleaning liquid spraying and the descending of the downcomer 16 is realized, the cleaning liquid spraying and the descending of the downcomer are accurately matched, the cleaning and sewage discharging efficiency is improved, the operation error is reduced, and the automation degree is higher. And under the state of no stopping, the physical property data of the gas and the liquid discharged from the graphite tower body 1 are not over standard.

The cleaning liquid inlet 9 is positioned above the phosphoric acid raw material inlet 10, the demister 24 is arranged inside the graphite tower body 1 between the phosphoric acid raw material inlet and the phosphoric acid raw material inlet, and the demister 24 is used for removing gas mist entrainment and micro liquid drops in gas, so that the gas-liquid separation efficiency of the equipment can be improved.

The connecting shaft 12 and the downcomer 16 penetrate through the tower plate 7 and are connected with the tower plate in a sliding and sealing manner, and the sliding and sealing connection structure is a double-O-shaped-ring piston sealing structure, so that the sealing performance is improved, and gas and liquid are prevented from permeating from the connecting shaft; the interior of the downcomer 16 is fixedly connected with the connecting shaft 12 through a connecting frame 29, so that the downcomer 16 can be driven to move together when the connecting shaft 12 moves.

The graphite tower body 1 is formed by coaxially stacking a plurality of graphite tower sections 25 from bottom to top, the graphite tower sections 25 are of cylindrical annular structures, the outer surfaces of the graphite tower sections 25 are regular polygons, and the inner surfaces of the graphite tower sections are cylindrical. The outer surface of the graphite tower section 25 is designed into a polygonal columnar body, which is equivalent to the graphite tower body 1 longitudinally provided with a reinforcing rib, so that the strength is good, the stability is high, and the appearance is more beautiful.

Graphite tower section 25 is by 26 annular mosaic structures of graphite piece, and the concatenation form is tongue-and-groove formula joint seam structures, can improve joint strength, and the impermeability is better, and the stable performance is reliable. The carbon fiber resin composite material is wound outside each graphite tower section 25, so that circumferential reinforcement can be realized, and the pressure resistance is higher. The upper graphite tower section 25 and the lower graphite tower section 25 are connected in a pressing and sealing mode through gaskets.

The graphite tower body 1 upper portion is equipped with graphite upper cover, graphite upper cover is circular flat plate structure, be equipped with gas material outlet 2 on the graphite upper cover, graphite upper cover top is equipped with the upper cover plate, graphite tower body 1 bottom is graphite low head, graphite low head bottom is equipped with the lower cover plate, the lower cover plate bottom is equipped with the apron seat, be equipped with the round between upper cover plate and the lower cover plate around the fastening bolt around graphite tower body 1, carry out whole fastening to the tower body through fastening bolt, and carry out pressure compensation through the pressure spring who establishes on fastening bolt upper portion.

The graphite low head is the tapered head, and graphite low head lower part is equipped with liquid material export 3, and 3 upper portions in the liquid material export are equipped with filter 27 for filter subsides to the impurity in the liquid of graphite tower body 1 bottom. The metal conical clamp 28 is arranged outside the graphite lower end socket, and the graphite lower end socket has the largest pressure bearing in the using process, so that a special conical steel clamp structure is adopted, the pressure bearing capacity of the graphite lower end socket is improved, the reinforcing stress structure is reasonable in design, the reinforcing effect is good, and the performance is stable and reliable.

The gas material outlet 2 is connected with the vortex separator 5 through a pipeline, and the vortex separator 5 can realize solid-liquid separation and solid sedimentation, thereby ensuring that the equipment does not stop and the whole tower discharges sewage. The vortex separator 5 is connected with a reboiler 6, and the other end of the reboiler 6 is connected with a material gas-liquid mixture inlet 4.