CN113262739B

CN113262739B - Hydraulic extrusion method integrating reaction crystallization, slurry washing, filtering and drying functions

Info

Publication number: CN113262739B
Application number: CN202110389342.7A
Authority: CN
Inventors: 陈崔龙; 张德友; 朱碧肖; 丁建国; 邓超
Original assignee: HEFEI GENERAL ENVIRONMENT CONTROL TECHNOLOGY CO LTD; Hefei General Machinery Research Institute Co Ltd
Current assignee: HEFEI GENERAL ENVIRONMENT CONTROL TECHNOLOGY CO LTD; Hefei General Machinery Research Institute Co Ltd
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2022-09-27
Anticipated expiration: 2041-04-12
Also published as: CN113262739A

Abstract

The invention relates to the technical field of solid-liquid separation, in particular to a hydraulic extrusion method integrating reaction crystallization, slurry washing, filtering and drying functions. The invention at least comprises the following steps: (1) a reaction crystallization stage; (2) a dehydration stage formed by sequential connection of a gravity flow dehydration stage and a hydraulic extrusion filtration dehydration stage; (3) a slurrying and washing stage; (4) a filter cake drying stage; (5) and (5) a filter cake discharging stage. The invention can solve the problem that the traditional vertical filter can not have reaction crystallization simultaneously, can realize the functions of reaction crystallization, filtration and drying of materials by utilizing the hydraulic pressure extrusion effect, and is particularly suitable for compressible materials.

Description

Hydraulic extrusion method integrating reaction crystallization, slurry washing, filtering and drying functions

Technical Field

The invention relates to the technical field of solid-liquid separation, in particular to a hydraulic extrusion method integrating reaction crystallization, slurry washing, filtering and drying functions.

Background

With the development of technology and production requirements, the functional integration of the device is higher and higher. In the field of filtering equipment, a three-in-one type filter appears, integrates three functions of filtering, washing and drying into one machine, shortens the process transfer, improves the production efficiency, reduces the labor intensity, has good adaptability to various materials, is particularly suitable for treating slurry which is difficult to filter and combustible, explosive, toxic, volatile, easily-polluted and other materials, is ideal equipment for solid-liquid separation in industrial departments such as medicines, pesticides, foods, chemical industry, dyes and the like, and has wide application. The three-in-one filter is a vertical tank container, mainly comprises main components such as a transmission component, a lifting component, a paddle mechanism, a filter disc and the like, wherein the paddle mechanism can be lifted and rotated positively and negatively, can be used for pulping and washing filter cakes, can accelerate the washing process, reduces the consumption of washing liquid and has better washing effect; the three-in-one filter adopts a pressurizing and filtering mode, and is pressurized by taking compressed gas such as air or nitrogen and the like as a pressure source, so that pressure difference is formed at two sides of a filter disc, moisture in materials is removed, a filter cake is intercepted, and the materials are automatically removed by blades after being dried. The working mode is just the same, so that the three-in-one filter has the following problems during filter pressing and dehydration: first, a large amount of compressed gas is required, making the operating cost high. Secondly, once the materials contain volatile organic compounds or toxic and harmful substances, the organic compounds or the toxic and harmful substances can also volatilize into the compressed gas, and then a large amount of waste gas is generated. It is common practice in the industry to subject the exhausted waste gas to additional treatment such as recycling or incineration, which obviously increases the operating cost. Thirdly, the bottom of the three-in-one filter is provided with a filter screen, the bottom of the filter screen is a mother liquor collecting cavity, and the structure can not meet the requirement of reaction crystallization in the same container. Because reaction liquid gets into jar body after, can get into filter screen and mother liquor and collect the chamber, go on along with reaction time, the crystal is appeared, can block up the filter screen, and the crystal also can flow away along with the mother liquor in the mother liquor collection chamber, not only need frequently carry out online maintenance to the filter screen, wastes time and energy, also can cause the extravagant phenomenon of raw materials, awaits the opportune moment to solve.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtering and drying, can solve the problem that the traditional vertical filter cannot have the reaction crystallization simultaneously, can realize the functions of reaction crystallization, filtering and drying of materials by utilizing the hydraulic pressure extrusion effect, and is particularly suitable for compressible materials.

In order to achieve the purpose, the invention adopts the following technical scheme:

a hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying is characterized in that: the hydraulic extrusion method comprises a hydraulic extrusion all-in-one machine, wherein the hydraulic extrusion all-in-one machine comprises a rack and a vertical filter cylinder arranged on the rack, and a piston cover capable of axially reciprocating along a filter cylinder cavity and a lower filter screen for filtering materials are sequentially arranged from top to bottom along the axial direction of the filter cylinder; the piston cover and the lower filter screen divide the filter cylinder cavity into an upper cavity, a lower cavity and a bottom filter liquid cavity from top to bottom in sequence; a passing gap for materials to flow between the upper cavity and the lower cavity is reserved between the outer edge of the piston cover and the cavity wall of the filter cylinder, an inflatable expansion bag is coaxially arranged at the outer edge of the piston cover, and the passing gap can be blocked when the expansion bag performs expansion action; a feed port is arranged at the top end of the filter cylinder, an openable slag discharge port communicated with the lower cavity is arranged on the side wall of the filter cylinder, and a liquid outlet is arranged at the bottom end of the filter cylinder so as to be communicated with external equipment and a bottom-layer filtrate cavity; a filter pressing surface for filter pressing of materials is arranged on the bottom surface of the piston cover, and two paths of preset pipelines are arranged in the piston cover, wherein one path of preset pipeline forms an air inlet cavity so as to communicate the expansion bag with a compressed air source, and the other path of preset pipeline forms a negative pressure cavity so as to communicate a filter hole at the filter pressing surface with a negative pressure assembly;

the hydraulic extrusion method comprises the following steps:

a reaction crystallization stage: when the piston cover descends to a specified height, the compressed air source is started, the expansion bag is inflated and keeps a certain pressure, and the sealing property of the upper cavity is ensured; at the moment, the bottom layer filtrate cavity and the lower cavity are both isolated from the upper cavity and cannot be influenced by the crystallization of the reaction liquid; after the reaction liquid for reaction crystallization enters the upper cavity from the feeding hole, the reaction liquid starts to react and crystallize after the feeding is finished; after the reaction liquid finishes the reaction crystallization process, crystal particles are separated out, and a saturated suspension is formed, the reaction crystallization process is finished, and the equipment enters the next stage;

a dehydration stage; this phase can be divided into two processes: a self-flowing dehydration stage and a hydraulic extrusion filtration dehydration stage;

a gravity flow dehydration stage: after the reaction crystallization process is finished, the expansion bag exhausts air, the sealing is released, the outer circumferential surface of the expansion bag is reduced, a passing gap is formed between the expansion bag and the wall of the filter cylinder, the lower cavity, the upper cavity and the bottom layer filtrate cavity are communicated, the suspension enters the lower cavity from the upper cavity through the passing gap, liquid in the suspension flows away through the liquid outlet under the action of gravity, and crystal particles are intercepted at the lower filter screen to form a filter cake, namely a self-flowing dehydration stage;

and (3) a hydraulic extrusion filtration dehydration stage: when the self-flowing dehydration stage is carried out for a set time, because the filter cake is thicker and the filtration resistance is increased, the water yield through self-flowing is smaller and smaller, at the moment, the filtration is accelerated by means of external force, and the stage enters a hydraulic extrusion filtration dehydration stage; the piston cover moves downwards, and meanwhile, the expansion bag is inflated to form a sealing state, so that the residual suspension is sealed in the lower cavity; the piston cover gradually extrudes the material in the lower cavity, and the water finally flows away through the liquid outlet through the lower filter screen; along with the extrusion, the filter cake is thicker and thicker, the filtering resistance is larger and larger, and the water on the upper layer of the filter cake is difficult to penetrate through the filter cake; at the moment, the negative pressure assembly is started, and under the action of negative pressure, the water on the upper layer of the filter cake is sucked out through the negative pressure cavity at the piston cover; after the dehydration stage is finished, the expansion bag exhausts air, the sealing state is released, and the piston cover resets at the same time;

a filter cake discharging stage; after the process is completed, the clean filter cake needs to be removed, and at the moment, the slag discharging port is opened to realize slag discharging operation.

Preferably, the piston cover is in a cylindrical shape with a downward barrel opening, the hydraulic extrusion all-in-one machine further comprises a hollow tubular main shaft for driving the piston cover to generate axial reciprocating motion, and the main shaft vertically penetrates through the outer wall of the filter cylinder along the axial direction of the filter cylinder and forms power fit with a linear power source positioned at the top of the filter cylinder; the central tube is coaxially arranged at the cavity of the main shaft, an annular cavity channel formed by enclosing the outer wall of the central tube and the cavity wall of the main shaft tube forms the air inlet cavity, the air channel communicated with the air inlet cavity extends along the barrel bottom of the piston cover in the radial direction, then extends along the barrel wall of the piston cover in the axial direction and is communicated to the annular air uniform cavity, and the annular air uniform cavity is provided with an air hole used for communicating with the air bag cavity of the expansion air bag; the central tube cavity forms the negative pressure cavity, and the barrel opening of the piston cover is covered with the upper pore plate, so that the upper pore plate and the barrel cavity of the piston cover are jointly enclosed to form a liquid accumulation cavity for temporarily retaining the filtrate, and the filtrate is discharged out of the filter cylinder cavity through the sieve pores of the upper pore plate and the negative pressure cavity.

Preferably, the linear power source is a hydraulic cylinder; a spray head for performing a slurry washing function is arranged on the top wall of the filter cylinder, and a stirring paddle for performing a stirring function is axially and convexly arranged on the lower plate surface of the upper pore plate; the top end of the filter cylinder is also provided with a speed reducer, and the main shaft is matched with an output gear of the speed reducer through a spline; the dehydration stage is more than two times, and after the first dehydration stage is completed, the pulp washing stage is carried out: the liquid outlet is closed, and the washing liquid enters from the spray header; after the feeding of the washing liquid is finished, the piston cover does up-and-down lifting motion and simultaneously does or does only do rotary motion, thereby achieving the purpose of pulping; and after pulping and washing, stopping the action of the piston cover and resetting to a high position, opening the liquid outlet and entering a second dehydration stage.

Preferably, the filter cylinder is formed by combining an upper cylinder and a lower cylinder which are coaxially and axially arranged from top to bottom in sequence, the inner wall of the lower cylinder forms a matching wall for matching with an expanded expansion bag, and a slag discharge port and a liquid outlet are formed in the lower cylinder.

Preferably, a coil pipe with a heating function is arranged at the bottom surface of the lower cylinder, and a hollow interlayer capable of heating materials in the filter cylinder is arranged at the wall of the filter cylinder; after the dehydration stage is completed, entering a filter cake drying stage: heat sources are introduced into the hollow interlayer and the coil pipe to heat the filter cake; at the same time, the piston cover rotates to accelerate the drying process; and after the filter cake drying stage is finished, the piston cover stops acting and resets to a high position, the slag discharging port is opened, and the filter cake discharging stage is started.

Preferably, the piston cover is coaxially and penetratingly provided with a connecting seat for connecting the spindle; the connecting seat is in a cylindrical shape with an upward barrel opening, and the bottom end of the main shaft is coaxially inserted into the barrel cavity of the connecting seat and forms rotation stopping fit with the barrel cavity; after entering through the air inlet cavity at the main shaft, the air radially penetrates through the connecting seat and enters into the bag cavity of the expansion bag through an air passage preset in the piston cover.

Preferably, the cross section of the expansion bag is in a U-shaped groove shape with an opening facing to the direction of the piston cover, and two groove walls of the expansion bag are respectively fixed at the piston cover through a group of compression rings in a pressing mode.

Preferably, in the axial direction of the main shaft, a fit clearance for filtrate to pass through is reserved between the upper orifice plate and the connecting seat.

Preferably, an axial gap is reserved between the main shaft and the bottom surface of the barrel of the connecting seat, the axial gap forms a liquid collecting cavity, and the radial hole is communicated with the liquid accumulating cavity and the liquid collecting cavity.

Preferably, an upper filter screen is attached to the bottom plate surface of the upper orifice plate; the filter holes at the upper filter screen are communicated with the sieve pores at the upper pore plate, and the aperture of the filter holes at the upper filter screen is smaller than that of the sieve pores at the upper pore plate; the upper plate surface of the lower pore plate is attached with a layer of lower filter screen, the filtering holes at the lower filter screen are communicated with the sieve pores at the lower pore plate, and the aperture of the filtering holes at the lower filter screen is smaller than that of the sieve pores at the lower pore plate.

The invention has the beneficial effects that:

1) through the scheme, the invention can realize a whole set of reaction crystallization, filtration and drying processes of materials by using hydraulic pressure extrusion through one machine; the invention not only solves the problem that the vertical filter can not have reaction crystallization, but also realizes the purpose of maximally drying the filter cake, and has remarkable effect. Practice proves that the maximum cylinder diameter of the filter cylinder can reach more than 3500mm, the filter area is more than 9 square meters, the effective volume is more than 10m3, and the filter cylinder can meet the requirement of large-scale production. The hydraulic pressure extrusion effect is filtered, no waste gas is generated, and the filter is particularly suitable for compressible materials.

2) The invention has the advantages that the operation of reaction crystallization, dehydration, drying and filter cake unloading is realized, and simultaneously, the invention also has the function of slurrying and washing, so that the effect of removing impurities, acid radicals or salt and the like can be expected to be achieved, and the filter cake with higher purity can be obtained. Furthermore, the invention also has the function of drying filter cakes so as to ensure the integration and the multiple purposes of one machine.

3) The structure of the filter cartridge is designed as another highlight of the present invention. Different from the traditional integral filter cylinder, due to the existence of the expansion bag at the piston cover, the filter cylinder is designed to form a combined structure of an upper cylinder body and a lower cylinder body, so that when the filter cylinder is actually manufactured, the wall part of the lower cylinder body is thickened and finely machined, the expansion bag can be ensured to have enough matching reliability and achieve a preset sealing effect when being matched with the wall of the lower cylinder body under huge inflation pressure.

4) In the invention, the expansion bag at the piston cover is a core part; in actual design, the expansion bag can realize the expansion function by pumping and injecting liquid, and can also realize the controllable contraction and expansion effects of the expansion bag in a gas pumping and injecting mode. During specific design, gas enters the expansion bag through the main shaft tube cavity and the air passage; more specifically, the gas can enter the air passage through an air inlet cavity formed by the main shaft pipe cavity wall and the central pipe in sequence, and finally flows into the bag cavity of the expansion bag through the air hole at the annular air uniform cavity, so that the online air charging and discharging function of the expansion bag is ensured on the premise that the piston cover can generate axial reciprocating motion, and the compactness and the working reliability of the structure can be effectively ensured.

5) The expansion bag can be an independent annular tubular bag body, or a groove-shaped bag is adopted, so that the aim of positioning relative to the piston cover is fulfilled by utilizing the pressing function of the upper and lower groups of pressing rings, the gas inlet and outlet effects are realized by the dead alignment of the notch of the expansion bag and the gas hole, and the operation is extremely reliable and stable.

6) The arrangement of the upper filter screen aims to lay a foundation for secondary filtrate extraction while the piston cover has an original axial pressure application function. In other words, the piston cover can be simply used as a piston structure to physically separate the upper cavity from the lower cavity and directly apply pressure to the material at the lower cavity, so that the purpose of filtering and separating filter cakes and filtrate is achieved; the filter liquor in the lower cavity can be naturally discharged through the lower hole plate of the lower filter screen, and when the filter liquor can not normally drip or only slightly drip under the natural gravity, the filter liquor respectively passes through the lower filter screen and the upper filter screen by downward pressing of the piston cover, so that the aim of bidirectional synchronous discharge of the filter liquor in the material is fulfilled, and the quality of a finally formed filter cake can be obviously improved. The precision of the upper filter screen is selected according to the particle size of the material and is generally the same as that of the lower filter screen.

7) The arrangement of the upper orifice plate aims to increase the rigidity of the upper filter screen while forming the liquid accumulation cavity in the piston cover, and prevent the upper filter screen from being damaged by force under the action of hydraulic extrusion; the lower orifice plate and the lower filter screen are the same. When necessary, the stirring paddle can be additionally arranged or even attached to the washing machine, so that the purpose of on-line stirring type washing for the washing liquid is achieved, and the washing machine has a multi-purpose function.

8) The arrangement of the fit clearance is used for ensuring the balance of filtrate in the effusion cavity, so that the filtrate can be uniformly and orderly discharged from the radial holes arranged on the connecting seat along the circumferential direction. The axial gap is used for the initial convergence of the filtrate in the liquid converging cavity, and finally the filtrate flows out of the central tube together to the outside of the invention, and the details are not repeated here.

Drawings

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

FIG. 2 is an enlarged view of a portion I of FIG. 1;

FIG. 3 is an enlarged view of a portion II of FIG. 1;

FIG. 4 is an enlarged view of a portion III of FIG. 1;

FIG. 5 is a cross-sectional view of the piston cap;

FIG. 6 is a cross-sectional view taken along line A-A of FIG. 5;

FIG. 7 is a bottom view of FIG. 5;

FIG. 8 is a diagram of the working condition of the present invention at the reaction crystallization stage;

FIG. 9 is a diagram of the operation of the present invention in the gravity dewatering stage;

FIG. 10 is a diagram illustrating the operation of the present invention during the hydraulic press filtration dewatering stage;

FIG. 11 is a diagram of the present invention in operation during the slurry wash stage;

fig. 12 is a working state diagram of the invention in a filter cake discharge stage.

The actual correspondence between each label and the part name of the invention is as follows:

a-upper chamber b-lower chamber c-bottom layer filtrate chamber d-passing gap

e-air inlet cavity f-negative pressure cavity g-dropsy cavity h-liquid collecting cavity i-radial hole

11-piston cap 11 a-air flue 11 b-annular uniform air cavity 11 c-air hole

12-main shaft 12 a-central tube 13-expansion bag 14-connecting seat 15-pressing ring

16-upper orifice plate 17 a-stirring paddle 17 b-attached paddle 18-upper filter screen

19 a-radial support rib 19 b-radial reinforcing rib

20-frame 30-cartridge

30 a-upper cylinder 30 b-lower cylinder 30 c-coil 30 d-hollow interlayer

31-feed inlet 32-slag discharge outlet 33-liquid outlet

40-lower orifice 51-hydraulic cylinder 52-speed reducer 60-spray head 70-lower filter screen

80-compressed air source 90-negative pressure assembly

Detailed Description

For ease of understanding, the specific construction and operation of the invention is described further herein as follows:

the concrete structure of the invention is shown in fig. 1-12, and the structure mainly comprises a main shaft 12, a bearing seat, a speed reducer 52, a hydraulic cylinder 51, a filter cylinder 30 and a piston cover 11 which form a hydraulic extrusion type all-in-one machine. Wherein:

the filter cartridge 30 is mounted on the frame 20 as shown in fig. 1 and is formed by combining an upper cylinder 30a and a lower cylinder 30 b; the inlet port 31 is located at the top end of the upper cylinder 30a, the slag discharge port 32 is located at the side wall of the lower cylinder 30b, and the outlet port 33 is located at the bottom end of the lower cylinder 30 b. More specifically: the upper cylinder 30a is generally composed of a seal head and a straight cylinder, and is connected with the lower cylinder 30b to form a closed cavity for containing materials, which is a main place for the materials to work. The main shaft 12 is arranged coaxially with the upper cylinder 30a, passes through the upper cylinder 30a, and is connected to the speed reducer 52. The main shaft 12 can rotate driven by the speed reducer 52. The upper part of the main shaft 12 is provided with a bearing seat, two sides of the bearing seat are uniformly distributed and connected with hydraulic cylinders 51, and the number of the hydraulic cylinders 51 is generally two, so that the hydraulic power supply unit for extrusion and filtration of the all-in-one machine is provided. Under the action of the hydraulic cylinder 51, the main shaft 12 and the accessories fixed on the main shaft 12, such as the bearing seat and the piston cover 11, perform up-and-down motion synchronously. In order to synchronously ensure that the main shaft 12 can generate rotation and lifting actions, a bearing fit can be formed between the main shaft 12 and the hydraulic cylinder 51, and a key type meshing transmission fit can be formed between the main shaft 12 and a power output shaft of the speed reducer 52.

Further, a hollow interlayer 30d is arranged outside the filter cartridge 30, and a heat source can be introduced according to the process requirement, so that the material in the filter cartridge 30 can be heated. The hollow interlayers 30d may also be arranged to form a structure resembling a disc tube. In order to increase the heat exchange area, the bottom of the lower cylinder 30b is provided with a coil 30c for exchanging heat with the material from the bottom. As shown in fig. 4, the upper surface of the lower cylinder 30b is provided with a lower filter screen 70, the accuracy of which is selected according to the particle size of the material, and the lower filter screen plays a role in intercepting material solids and flowing away liquid, and the flowing away liquid forms mother liquid and is discharged through the liquid outlet 33. As shown in fig. 1 and 4, the lower screen 70 is fixed to the lower perforated plate 40 to increase rigidity and prevent the lower screen 70 from being damaged by hydraulic pressure. The slag hole 32 can be closed by a slag discharge cover. In the stage of slag discharging and discharging, the slag discharging cover is opened. Besides manual opening of the slag discharge cover, automatic opening or solid discharge valve can be provided.

The straight section of the filter cartridge 30 generally consists of an upper straight section and a lower straight section, and the wall thickness of the lower straight section is thicker, so that the lower straight section needs to bear certain extrusion force; and secondly, fine machining is needed to obtain a higher matching size so as to form size matching with the expansion bag 13 to achieve a sealing effect. The height of the lower straight section is designed according to parameters such as effective volume, solid slag holding capacity and the like. The wall thickness of the upper straight section can be thinner, and fine machining is not needed; the difference in wall thickness between the upper straight section and the lower straight section is also one of the factors for forming the annular channel, i.e. the passing gap d, as shown in fig. 2. In addition, as shown in fig. 1, the upper cylinder 30a is provided with a feed inlet 31 at the end socket, through which the material enters the interior of the filter cylinder 30. In addition, a spray head 60 is provided, so that washing liquid enters to wash the filter cake; and simultaneously, the interior of the filter cartridge is rinsed. After the expansion bladder 13 is inflated, as shown in fig. 8, 10 and 12, it can cooperate with the lower straight section to form an annular seal, so as to seal and isolate the cavity of the filter cartridge 30, and form an upper cavity a and a lower cavity b; of course, the lower chamber b and the lower filtrate chamber c are always connected to the lower perforated plate 40 through the lower strainer 70. The inflation bladder 13 is lifted in an axial direction by the cooperation of the hydraulic cylinder 51 and the piston cap 11, so that the volumes of the upper chamber a and the lower chamber b are adjustable and variable. When the expansion bladder 13 is not inflated, as shown in fig. 9 and 11, the diameter of the outer periphery of the expansion bladder 13 is reduced, which is another factor for forming a circular passage, i.e., a passage gap d.

In the specific assembly, as shown in fig. 1, 2 and 5, the expansion bladder 13 is pressed against the outer periphery of the piston cap 11 by the lower pressing ring 15 and the upper pressing ring 15. The expansion bladder 13 may be "U" shaped to form a sealed chamber with the outer periphery of the piston cap 11. The material of the expansion bag 13 has a certain elasticity, such as various rubbers, thin-walled polytetrafluoroethylene plastics, and the like. In order to realize the inflation or deflation of the expansion bag 13, a series of air holes 11c are uniformly distributed on the outer ring of the piston cover 11, an air passage 11a is also arranged inside the piston cover 11, and the air holes 11c are communicated with the air passage 11 a. Connecting seat 14 at piston cap 11 is in the shape of a barrel with its opening facing upwards, i.e. the bottom of connecting seat 14 is closed, and its inner circumference is connected with the lower shaft end of main shaft 12 in a matching manner. The main shaft 12 is a hollow structure, and is coaxially inserted into a central tube 12a to be matched with the lumen of the main shaft 12. The bottom of the central tube 12a is provided with a sealing structure which seals the outer circumference of the central tube 12a with the tube cavity at the lower part of the main shaft 12 to form an annular air homogenizing chamber 11 b. Meanwhile, as shown in fig. 1, a rotary joint is coaxially arranged at the top end of the hollow structure of the main shaft 12, the rotary joint has two interfaces, namely an air inlet interface and an air outlet interface, and the air inlet interface is communicated with the annular air uniform cavity 11b so as to realize the air charging and discharging functions of the expansion bladder 13. Meanwhile, a negative pressure interface communicated with the negative pressure assembly 90 is arranged, and the negative pressure interface is communicated with a tube cavity of the central tube 12a, namely a negative pressure cavity f. For sealing, corresponding sealing structures are arranged at the lower end of the main shaft 12, the joint of the annular gas homogenizing cavity 11b and the air passage 11a and other matching positions to ensure that gas at the joint does not leak.

For the requirements of adjustment, control, display and the like, instruments and meters such as a regulating valve, a reversing valve, a pressure gauge and the like can be arranged between the compressed air source 80 and the air inlet interface. When the expansion bag 13 needs to be inflated to achieve the sealing effect, the compressed air source 80 provides air with a certain flow and pressure, the air enters from the air inlet port, enters the annular air uniform cavity 11b to the air hole 11c through the air passage 11a, and finally enters the U-shaped cavity body of the expansion bag 13 to promote the expansion bag 13 with certain elasticity to expand to achieve the sealing effect. And the expansion bag 13 has the functions of certain compensation and irregular cavity filling, and can achieve better sealing effect when materials exist on the sealing surface. When the expansion bag 13 needs to be exhausted to achieve the purpose of releasing the seal, the gas in the expansion bag 13 is reversed through the reversing valve, enters the annular gas homogenizing chamber 11b from the gas hole 11c to the gas channel 11a, and then reaches an exhaust interface from the gas inlet chamber e at the main shaft 12 to be exhausted. When the expansion bag 13 is exhausted and the sealing is released, the outer circumferential surface is reduced, and a passing gap d for passing the materials is exposed.

For the specific construction of the piston cap 11, reference is made to fig. 3, 5 and 6: the upper orifice plate 16 is fixedly arranged at the lower part of the piston cover 11, an annular liquid accumulation cavity g is formed by an inner cylinder at the lower part of the piston cover 11, the upper orifice plate 16 and the outer circumference of the connecting seat 14, and corresponding sealing is arranged on the outer circumferential surface of the upper orifice plate 16 to ensure the sealing of the liquid accumulation cavity g. And a layer of upper filter screen 18 with higher precision is attached to the upper orifice plate 16, the precision is selected according to the particle size of the material, the action of intercepting material solids and flowing away liquid is realized, and the flowing away liquid forms mother liquid and enters the liquid accumulation cavity g. The upper filter screen 18 is fixedly arranged on the upper hole plate 16, so that the rigidity is increased, and the upper filter screen 18 is prevented from being damaged by force under the action of hydraulic extrusion. In order to prevent the upper orifice plate 16 from deforming and damaging during hydraulic extrusion of materials, radial support ribs 19a are uniformly distributed in the liquid accumulation cavity g, the radial support ribs 19a are welded with three surfaces of the piston cover 11, and the bottom of the radial support ribs is in contact with the upper orifice plate 16 to play a supporting role. Each radial support rib 19a is chamfered to form an outer channel. Each radial support rib 19a is higher than the bottom of the connecting seat 14 to form an inner channel; the outer channel and the inner channel enable the hydrops chamber g to be communicated, and the hydrops chamber g is prevented from being separated by the radial support ribs 19 a. In addition, an axial clearance is reserved between the main shaft 12 and the barrel bottom surface of the connecting seat 14, the axial clearance forms a liquid collecting cavity h, and the liquid accumulating cavity g is communicated with the liquid collecting cavity h through a radial hole i. The liquid collecting cavity h is communicated with the cavity of the central tube 12a and finally communicated with the negative pressure interface. When the piston cover 11 is under the hydraulic action of the hydraulic cylinder, the material is gradually extruded, and the water passes through the lower filter screen 70 and finally flows away through the liquid outlet 33 through the lower hole plate 40. As the press progresses, the cake becomes thicker and more resistant to filtration, and water from the upper layer of the cake can hardly penetrate the cake and is drained away by the lower screen 70. At this time, the negative pressure assembly 90 can be opened, and under the action of suction force, the water on the upper layer of the filter cake penetrates through the upper filter screen 18 and the upper orifice plate 16 to enter the liquid accumulation cavity g, then enters the pipe cavity of the central pipe 12a through the radial hole i and the liquid collection cavity h, and finally is discharged through the negative pressure interface. Under the combined action of the upper filter screen 18 and the lower filter screen 70, the water content of the filter cake can be greatly reduced, and more mother liquor and drier solids can be obtained.

In addition, as shown in fig. 7, an S-shaped stirring paddle 17a is further provided at the lower orifice plate 40, the stirring paddle 17a may be a double-paddle or a triple-paddle, and the arrangement of the stirring paddle 17a is related to the turning direction of the main shaft 12, that is, during discharging, the rotation of the main shaft 12 can drive the stirring paddle 17a to drive the filter cake from the center to the periphery, and finally the filter cake is discharged from the slag discharge port 32 at the side of the lower straight section. The stirring paddle 17a in fig. 7 is a double-paddle structure, and when the main shaft 12 rotates clockwise, the stirring paddle 17a can drive the filter cake from the center to the periphery. The stirring paddles 17a can also serve the purpose of stirring and mixing in the beating washing stage. As shown in fig. 5-6, radial ribs 19b are uniformly distributed on the upper portion of the piston cap 11 to reinforce the strength of the piston cap 11 and prevent the piston cap 11 from deforming during extrusion. Meanwhile, in the reaction crystallization stage, the main shaft 12 rotates slowly, and the reinforcing ribs play roles in stirring and mixing, so that the reaction process is accelerated. If the stirring and mixing intensity of the reinforcing ribs is not enough, the auxiliary paddles 17b can be additionally arranged to enhance the mixing effect.

The following description is given in connection with each working stage of the hydraulic extrusion type all-in-one machine:

(1) the reaction crystallization stage is shown in FIG. 8.

At this time, in order to make the reaction liquid volume as large as possible, the piston cap 11 is lowered to the lowest position by the hydraulic cylinder, and the upper chamber a reaches the maximum volume. The lowest position of the piston cover 11 is determined by the stroke of the hydraulic cylinder, and it is ensured that the lower end surface of the paddle 17a does not touch the lower screen 70 at the lowest position, so as to protect the accuracy of the lower screen 70, and a certain gap is generally reserved between the two. After the piston cover 11 is lowered to the low position, the compressed air source is opened, the expansion bag 13 is inflated and keeps a certain pressure, and the sealing performance of the upper cavity a is ensured. At this time, the lower screen 70 and the upper screen 18 are both located in the lower chamber b, and are isolated from the upper chamber a, and are not affected by the crystallization of the reaction solution. And after the reaction liquid for reaction crystallization enters the upper cavity a from the feeding hole 31, the reaction liquid starts to react and crystallize after the feeding is finished. According to the process requirement, the reaction crystallization process can be heated, and the hollow interlayer 30d and the coil pipe 30c can be both introduced with heat sources to heat the reaction liquid in the upper cavity a. At the same time, the speed reducer 52 can be turned on, and the reaction solution can be stirred and mixed by the reinforcing ribs and the auxiliary paddles 17b on the piston cover 11. The reaction process is accelerated, and the output rotation speed of the speed reducer 52 can be adjusted through a frequency converter, so as to obtain a better stirring and mixing rotation speed. After a certain reaction time, the reaction liquid finishes the reaction crystallization process, crystal particles are separated out to form saturated suspension, the reaction crystallization process is finished, and the equipment enters the next stage.

(2) And (4) a dehydration stage. This stage can be divided into two processes, namely a gravity dewatering stage as shown in fig. 9 and a hydraulic squeeze filtration dewatering stage as shown in fig. 10.

At this time, the reaction crystallization process is finished, the reversing valve is opened, and the gas in the expansion capsule 13 reversely enters the gas channel 11a through the gas hole 11c and is finally discharged through the exhaust port. The expansion bag 13 finishes air exhaust and sealing release, the outer circumferential surface of the expansion bag 13 is reduced, a passing gap d is formed between the outer circumferential surface and the inner diameter of the inner cylinder of the lower straight section, the lower cavity b is communicated with the upper cavity a, and the suspension enters the lower cavity b from the upper cavity a through the passing gap d. Under the action of gravity, the liquid in the suspension flows through the lower screen 70, passes through the lower orifice 40 and the liquid outlet 33, and the crystal particles are retained on the surface of the lower screen 70 to form a filter cake, which is a self-flowing dehydration stage. When the expansion bag 13 is released, the piston cap 11 is driven by the hydraulic cylinder to rise to the highest position, which is determined by the stroke of the hydraulic cylinder. At this time, the piston cover 11 is in the upper straight section, and the passing clearance d reaches the maximum due to the difference of wall thickness between the upper straight section and the lower straight section.

When the gravity flow dehydration stage is carried out for a certain time, because the filter cake is thicker and thicker, the filtration resistance is increased, the water yield through gravity flow is smaller and smaller, at the moment, the filtration is accelerated by means of external force, and the invention starts to enter the hydraulic extrusion filtration dehydration stage: at this point, the hydraulic cylinder drives the piston cap 11 downwards, while the expansion bladder 13 inflates, creating a sealed condition, sealing the remaining suspension in the lower chamber b. Under the action of hydraulic force, the piston cover 11 gradually extrudes the material, and water passes through the lower filter screen 70 and finally flows away through the liquid outlet 33 through the lower orifice plate 40. As the press progresses, the cake becomes thicker and more resistant to filtration, and water in the upper layer of the cake is less likely to penetrate the cake and be removed by the lower screen 70. At this time, the negative pressure assembly can be opened, and under the action of suction force, the water on the upper layer of the filter cake can penetrate through the upper filter screen 18 and the upper orifice plate 16 to enter the liquid accumulation cavity g and finally be discharged from the negative pressure connector. Under the combined action of the upper filter screen 18 and the lower filter screen 70, the water content of the filter cake can be greatly reduced, and more mother liquor and drier solids can be obtained. When the stroke of the hydraulic cylinder is not changed any more and no mother liquor flows out from the negative pressure port and the liquid outlet 33, the dehydration stage is finished. The expansion bag 13 is exhausted to release the sealing state, and meanwhile, the hydraulic cylinder drives the piston cover 11 to rise to the highest position.

(3) The slurry wash stage, as shown with reference to FIG. 11:

when the dewatering stage is complete, a relatively dry cake layer is formed. If the filter cake layer needs to be washed to remove impurities, acid radicals or salts and the like so as to obtain the aim of higher purity, the method needs to enter a pulping and washing stage: at this time, the liquid outlet valve of the liquid outlet 33 is closed, the washing liquid enters from the spray header 60, the spray header 60 can be a 360-degree spray ball, can also be a common feeding pipeline, and can be set according to the process requirements; the type, the amount and the washing times of the washing liquid are also set by the process requirements. After a certain amount of washing liquid is fed, the piston cover 11 can move up and down under the action of the hydraulic cylinder, and simultaneously, the piston cover can rotate or rotate singly under the drive of the speed reducer 52. The reinforcing ribs, the attached paddles 17b and the stirring paddles 17a on the piston cover 11 fully stir and mix the filter cake and the washing liquid, thereby achieving the purpose of pulping. After a certain time, pulping and washing are finished, the piston cover 11 stops acting and is reset to a high position, the liquid outlet 33 is opened, and the dehydration stage is started again.

(4) And (3) a drying stage:

if the filter cake needs to be dried, the hollow interlayer 30d and the coil 30c can be both introduced with heat sources to heat the filter cake. Meanwhile, the piston cover 11 is lowered by the hydraulic cylinder and rotated by the reducer 52. The stirring paddle 17a turns over the cake layer to accelerate the drying process. Even negative pressure drying can be performed by the negative pressure assembly. The side of the filter cartridge 30 is close to the filter cake, and a temperature monitoring and sampling port can be arranged to monitor the temperature of the filter cake and sample and analyze the filter cake. After the drying process is finished, the piston cover 11 stops and returns to the high position.

(5) A filter cake discharge stage, as shown in fig. 12:

after the drying stage is complete, the clean filter cake needs to be removed. At this time, the slag discharge cover is opened, the piston cover 11 generates a descending motion under the action of the hydraulic cylinder, and simultaneously, the piston cover rotates under the driving of the speed reducer 52. The stirring paddle 17a gradually scrapes off the cake layer from top to bottom layer by layer, and the cake layer is driven to the cylinder wall from the center to the outside under the action of the stirring paddle 17a and finally discharged from the slag discharge port 32. The stirring paddle 17a can be in other structural types, and the stirring paddle needs to have the function of driving the materials from the center to the cylinder wall in the rotating process.

The above stages can realize the automatic and programmed operation of each stage through signals such as time setting, liquid level, weight and the like and supporting equipment such as an automatic valve, automatic feeding and the like; the monitoring of the key parts of the expansion bag 13 is realized through pressure and air quantity detection.

It will, of course, be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.

Claims

1. A hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying is characterized in that: the hydraulic extrusion method comprises a hydraulic extrusion all-in-one machine, wherein the hydraulic extrusion all-in-one machine comprises a frame (20) and a vertical filter cylinder (30) arranged on the frame (20), and a piston cover (11) capable of doing reciprocating axial motion along a cylinder cavity of the filter cylinder (30) and a lower filter screen (70) for filtering materials are sequentially arranged from top to bottom along the axial direction of the filter cylinder (30); the piston cover (11) and the lower filter screen (70) divide a cylinder cavity of the filter cylinder (30) into an upper cavity, a lower cavity and a bottom layer filtrate cavity from top to bottom in sequence; a passing gap for materials to flow between the upper cavity and the lower cavity is reserved between the outer edge of the piston cover (11) and the wall of the cavity of the filter cartridge (30), an inflatable expansion bag (13) is coaxially arranged at the outer edge of the piston cover (11), and the passing gap can be blocked when the expansion bag (13) performs expansion action; a feed inlet (31) is arranged at the top end of the filter cylinder (30), an openable slag discharge port (32) communicated with the lower cavity is arranged on the side wall of the filter cylinder (30), and a liquid outlet (33) is arranged at the bottom end of the filter cylinder (30) so as to communicate external equipment with the bottom-layer filtrate cavity; a filter pressing surface for filter pressing of materials is arranged on the bottom surface of the piston cover (11), and two preset pipelines are arranged in the piston cover (11), wherein one preset pipeline forms an air inlet cavity so as to communicate the expansion bag (13) with the compressed air source (80), and the other preset pipeline forms a negative pressure cavity so as to communicate a filter hole at the filter pressing surface with the negative pressure component (90);

the hydraulic extrusion method comprises the following steps:

(1) a reaction crystallization stage: the piston cover (11) descends to a designated height, the compressed air source is started, the expansion bag (13) is inflated and keeps a certain pressure, and the sealing property of the upper cavity is ensured; at the moment, the bottom layer filtrate cavity and the lower cavity are both isolated from the upper cavity and cannot be influenced by the crystallization of the reaction liquid; reaction liquid to be reacted and crystallized enters the upper cavity from the feeding hole (31), and after the feeding is finished, the reaction liquid starts to react and crystallize; after the reaction liquid finishes the reaction crystallization process, crystal particles are separated out, and a saturated suspension is formed, the reaction crystallization process is finished, and the equipment enters the next stage;

(2) a dehydration stage; this phase can be divided into two processes: a self-flowing dehydration stage and a hydraulic extrusion filtration dehydration stage;

a gravity flow dehydration stage: after the reaction crystallization process is finished, the expansion bag (13) exhausts air, the sealing is released, the outer circumferential surface of the expansion bag (13) is reduced, a passing gap is formed between the outer circumferential surface and the wall of the filter cylinder (30), at the moment, the lower cavity, the upper cavity and the bottom layer filtrate cavity are communicated, the suspension enters the lower cavity from the upper cavity through the passing gap, under the action of gravity, liquid in the suspension flows away through the liquid outlet (33), and crystal particles are intercepted at the lower filter screen (70) to form a filter cake, namely a self-flow dehydration stage;

and (3) a hydraulic extrusion filtration dehydration stage: when the self-flowing dehydration stage is carried out for a set time, because the filter cake is thicker and the filtration resistance is increased, the water yield through self-flowing is smaller and smaller, at the moment, the filtration is accelerated by means of external force, and the stage enters a hydraulic extrusion filtration dehydration stage; the piston cover (11) moves downwards, and meanwhile, the expansion bag (13) inflates to form a sealing state, so that the residual suspension liquid is sealed in the lower cavity; the piston cover (11) gradually extrudes the material in the lower cavity, and the water finally flows away through the liquid outlet (33) through the lower filter screen (70); along with the extrusion, the filter cake is thicker and thicker, the filtering resistance is larger and larger, and the water on the upper layer of the filter cake is difficult to penetrate through the filter cake; at the moment, the negative pressure assembly is started, and under the action of negative pressure, the water on the upper layer of the filter cake is sucked out through the negative pressure cavity at the piston cover (11); after the dehydration stage is finished, the expansion bag (13) exhausts air, the sealing state is released, and the piston cover (11) resets at the same time;

(3) a filter cake discharging stage; after the flow is completed, the clean filter cake needs to be removed, and at the moment, a slag discharge port (32) is opened to realize slag discharge operation;

the hydraulic extrusion all-in-one machine further comprises a hollow tubular main shaft (12) for driving the piston cover (11) to axially reciprocate, wherein the main shaft (12) vertically penetrates through the outer wall of the filter cylinder (30) along the axial direction of the filter cylinder (30) and forms power fit with a linear power source positioned at the top of the filter cylinder (30); a central pipe (12a) is coaxially arranged at the pipe cavity of the main shaft (12), an annular cavity channel formed by enclosing the outer wall of the central pipe (12a) and the pipe cavity wall of the main shaft (12) forms the air inlet cavity, and the air channel (11a) communicated with the air inlet cavity extends along the barrel bottom of the piston cover (11) in the radial direction and then extends along the barrel wall of the piston cover (11) in the axial direction and is communicated to the annular air uniform cavity (11 b); an air hole (11c) used for communicating the bag cavity of the expansion bag (13) is arranged at the annular air-homogenizing cavity (11 b); the tube cavity of the central tube (12a) forms the negative pressure cavity, and the barrel opening of the piston cover (11) is covered with an upper pore plate (16), so that the upper pore plate (16) and the barrel cavity of the piston cover (11) are enclosed together to form a liquid accumulation cavity for temporarily retaining filtrate; filtrate passes through the sieve pores of the upper orifice plate (16) and the negative pressure cavity until the filtrate is discharged out of the cavity of the filter cylinder (30);

the linear power source is a hydraulic cylinder (51); a spray head (60) for performing a slurry washing function is arranged on the top wall of the filter cylinder, and a stirring paddle (17a) for performing a stirring function is axially and convexly arranged on the lower plate surface of the upper pore plate (16); the top end of the filter cylinder (30) is also provided with a speed reducer (52), and the main shaft (12) is in spline fit with an output gear of the speed reducer (52); the dehydration stage is more than two times, and after the first dehydration stage is completed, the pulp washing stage is carried out: the liquid outlet (33) is closed, and the washing liquid enters from the spray header (60); after the washing liquid is fed, the piston cover (11) does lifting movement and simultaneously or singly does rotating movement to achieve the pulping purpose; after pulping and washing, the piston cover (11) stops acting and resets to a high position, the liquid outlet (33) is opened, and the secondary dehydration stage is started;

the filter cylinder (30) is formed by combining an upper cylinder (30a) and a lower cylinder (30b) which are coaxially and axially arranged from top to bottom in sequence, the inner wall of the lower cylinder (30b) forms a matching wall for matching with an expanded expansion bag (13), and a slag discharge port (32) and a liquid outlet (33) are formed in the lower cylinder (30 b);

a coil pipe (30c) with a heating function is arranged at the bottom surface of the lower cylinder body (30b), and a hollow interlayer (30d) capable of heating materials in the filter cylinder (30) is arranged at the wall of the filter cylinder (30); after the dehydration stage is completed, entering a filter cake drying stage: heat sources are introduced into the hollow interlayer (30d) and the coil pipe (30c) to heat the filter cake; at the same time, the piston cover (11) rotates to accelerate the drying process; after the filter cake drying stage is finished, the piston cover (11) stops acting and resets to a high position, the slag discharging port (32) is opened, and the filter cake discharging stage is started.

2. The hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying as claimed in claim 1, wherein: a connecting seat (14) which is coaxially arranged at the piston cover (11) in a penetrating way and used for connecting the spindle (12); the connecting seat (14) is in a barrel shape with an upward barrel opening, and the bottom end of the main shaft (12) is coaxially inserted into a barrel cavity of the connecting seat (14) and forms rotation stopping fit with the barrel cavity; after entering through the air inlet cavity at the main shaft (12), the air radially penetrates through the connecting seat (14) and enters into the bag cavity of the expansion bag (13) through an air passage (11a) preset in the piston cover (11).

3. The hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying as claimed in claim 2, characterized in that: the cross section of the expansion bag (13) is in a U-shaped groove shape with an opening facing the direction of the piston cover (11), and two groove walls of the expansion bag (13) are respectively pressed and fixed at the piston cover (11) through a group of pressing rings (15).

4. The hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying as claimed in claim 2, characterized in that: in the axial direction of the main shaft (12), a fit clearance for filtrate to pass through is reserved between the upper orifice plate (16) and the connecting seat (14).

5. The hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying as claimed in claim 2, characterized in that: an axial clearance is reserved between the main shaft (12) and the bottom surface of the barrel of the connecting seat (14), the axial clearance forms a liquid collecting cavity, and the radial hole is communicated with the liquid accumulating cavity and the liquid collecting cavity.

6. The hydraulic extrusion method integrating the functions of reaction crystallization, slurry washing, filtration and drying as claimed in claim 1, wherein: an upper filter screen (18) is attached to the bottom plate surface of the upper orifice plate (16); the filtering holes at the upper filtering net (18) are communicated with the sieve pores at the upper pore plate (16), and the aperture of the filtering holes at the upper filtering net (18) is smaller than that of the sieve pores at the upper pore plate (16); a layer of lower filter screen (70) is attached to the upper plate surface of the lower pore plate (40), the filtering holes at the lower filter screen (70) are communicated with the sieve pores at the lower pore plate (40), and the aperture of the filtering holes at the lower filter screen (70) is smaller than that of the sieve pores at the lower pore plate (40).