CN112316454A

CN112316454A - Thickening device

Info

Publication number: CN112316454A
Application number: CN202011144195.9A
Authority: CN
Inventors: 史旭; 李红飞; 刘洋; 张�林
Original assignee: Chongqing Technology Branch Spic Yuanda Environmental Protection Engineering Co ltd
Current assignee: National Electric Investment Group Yuanda Environmental Protection Engineering Co ltd
Priority date: 2020-10-22
Filing date: 2020-10-22
Publication date: 2021-02-05
Anticipated expiration: 2040-10-22
Also published as: CN112316454B

Abstract

The invention provides a thickener for separating saturated solution and solid matters contained in slurry, which is provided with an intracavity overflow pipe, so that the solid matter loss caused by salt bloom overflow is reduced, the pipeline blockage caused by salt bloom can be reduced, and the thickener is favorable for long-time efficient and stable operation.

Description

Thickening device

Technical Field

The invention relates to the field of solid-liquid phase separation, in particular to a thickener.

Background

The thickener is widely used in the industries of chemical engineering, pharmacy and the like, and is used for carrying out solid-liquid phase separation. Thickeners are typically used to separate the crystallized salts from the concentrated brine.

The principle of the conventional manner of separating the crystalline salt using a thickener is as follows. Heating the salt solution to 90-100 deg.C, evaporating water in evaporator, and introducing the slurry containing crystal salt into thickener when the salt solution is saturated and crystal salt is precipitated. The slurry is stratified in the thickener, essentially separating into an upper saturated solution (sometimes also referred to as supernatant) and crystalline salts that precipitate in the lower part of the solution. When the amount of slurry fed into the thickener is greater than the capacity of the thickener, the saturated solution above the solution will overflow from the top of the thickener into the overflow area. Thus, as slurry is added and saturated solution overflows and leaves the thickener, the proportion of solid deposits in the thickener will increase, resulting in a slurry with a higher solids content than the feed slurry. And (3) crystallizing and precipitating the solid salt at the bottom of the thickener, and when the solid content of the accumulated salt in the thickener meets the requirement, opening a valve at the bottom of the thickener, and allowing the crystallized salt and the residual solution to leave the thickener and enter a centrifugal machine for centrifugal dehydration to obtain salt particles with smaller water content (for example, less than 10%). The saturated solution overflowing from the overflow area returns to the evaporator to be evaporated.

The current thickeners still have drawbacks. In particular, since the slurry to be treated is a solid-liquid mixture, each outlet pipe is easily clogged, which causes time and cost for maintenance and cleaning.

There is still a need for further improvements to thickeners.

Disclosure of Invention

The present invention provides a thickener for separating a saturated solution and solids contained in a slurry, comprising:

a cavity with an inverted cone-shaped bottom part,

a slurry inlet located at the top of the chamber;

a slurry outlet at the bottom of the chamber;

a discharge valve located below the slurry outlet;

a discharge passage located below the discharge valve; and

an overflow port located on the sidewall between the top and bottom of the cavity;

it is characterized in that the preparation method is characterized in that,

the thickener also comprises an intracavity overflow pipe, wherein the intracavity overflow pipe is positioned in the cavity, the upper end of the intracavity overflow pipe is connected to the overflow port, and the lower end of the intracavity overflow pipe is highly open between the overflow port and the bottom.

Preferably, the volume of the cavity at the height between the lower end of the overflow pipe in the cavity and the overflow port is greater than 30% of the volume of the cavity at the height between the bottom of the cavity and the overflow port.

Preferably, the discharge channel is connected to a centrifuge, and

the nominal maximum solids content beta of the thickener is less than the maximum feed solids content allowed by the centrifuge,

wherein the nominal maximum solids content β of the thickener is calculated by:

wherein the content of the first and second substances,

ρ₁is the density of the solid material in question,

v₁in order to be the nominal bulk volume,

ρ₂the density of the clear solution;

v is the volume of the cavity of the thickener below the overflow port,

wherein the nominal packing volume is a volume of the cavity between the lower end of the intra-cavity overflow tube and a bottom of the cavity.

Preferably, the cone apex angle of the reverse taper is 30 ° to 90 °.

Preferably, the diameter of the discharge channel is larger than the slurry outlet.

Preferably, the discharge channel is connected to a centrifuge, and the feed inlet of the centrifuge is located directly below the discharge channel.

Preferably, the thickener further has a dilute solution wash device configured to provide dilute solution to the slurry outlet and/or the discharge valve.

Preferably, the side wall of the cavity has a hollow heat recovery wall cavity therein, the heat recovery wall cavity having a fluid inlet and a fluid outlet opening outside the side wall, wherein the fluid outlet is higher than the fluid inlet.

Preferably, the headspace of the chamber has a breather valve.

Drawings

Fig. 1 shows a typical structure of a current thickener.

Fig. 2 shows a photograph of salt bloom precipitated on the surface of the slurry inside the thickener.

Figure 3 shows another prior art overflow system for a thickener without a breather valve.

Fig. 4 shows a schematic view of an embodiment of the thickener of the invention.

Figure 5 shows a heat recovery wall cavity in a cavity of the invention.

Figure 6 shows a schematic diagram of one embodiment of the present invention.

Detailed Description

The invention provides an improved thickener to solve the problem that solid matters are easy to lose through an overflow outlet in the conventional thickener.

The material outlet of existing thickeners conventionally comprises a slurry outlet and an overflow outlet. The slurry outlet is located at the bottom of the thickener and is used for discharging the discharged slurry (or called thick liquid) with the solid content increased relative to the fed slurry out of the thickener. The discharge of the discharged slurry is usually controlled by switching of a discharge valve and the discharged slurry is subsequently conducted through a discharge pipe to a subsequent solid-liquid separation plant. The subsequent solid liquid separation device is typically a centrifuge. The overflow outlet is positioned on the side wall of the upper part of the thickener and is used for discharging the saturated solution separated from the upper layer out of the cavity of the thickener so as to continuously improve the solid content of the residual slurry in the cavity.

Fig. 1 shows a typical structure of a current thickener. The top of the thickener is provided with a slurry inlet 11 which is communicated with the evaporator, the bottom of the thickener is provided with a discharge valve m, and a downstream discharge pipe 12 is communicated with the centrifuge. The crystallized salt 13 is deposited in the lower part of the thickener. The top of the thickener has an overflow area 14 which communicates to the evaporator via a conduit 15. The top of the thickener also has a service population 16 and a breather valve 17. Breather valve 17 is used to communicate with the external environment, where appropriate, to maintain internal thickener pressure.

In overflow zone 14, the saturated solution will overflow when the slurry level in the thickener is higher than the overflow level. In fig. 1, the slurry overflows from the periphery of the top surface of the inner cylinder of the thickener in the center, flows down the right side along a slope, and is finally discharged through a pipeline 15.

The inventors of the present invention have found that in the actual operation of the thickener, salt crystallization occurs not only at the bottom of the thickener but also at the upper surface of the slurry in the thickener. When high-temperature strong brine containing crystal salt enters the thickener, on one hand, the crystal salt in the solution is precipitated at the bottom of the thickener, and on the other hand, the surface temperature is low due to heat dissipation of the surface of the solution, so that a large amount of crystal salt is precipitated on the surface of the solution to form salt bloom.

It should be understood that in the present invention, the thickener is described below generally in terms of salt crystallization and separation, for example, the slurry is described in terms of concentrated salt solution and the solid precipitate is described in terms of salt crystallization. However, the thickener of the present invention is not limited to use in separating salt crystals from concentrated brine, and may be used in any conventional use of thickeners.

Fig. 2 shows a photograph of salt bloom precipitated on the surface of the slurry inside the thickener. It can be seen that the salt layer on the surface of the solution has a large thickness and does not settle. In other words, the upper surface of the slurry in the thickener will form a floating solid salt bloom.

The inventor of the invention finds that the salt flower layer on the surface of the thickener is discharged along with overflow, which is not beneficial to collection and causes waste of precipitated salt.

Furthermore, the inventors of the present invention have also found that the presence of the salt bloom described above can lead to plugging of the associated piping in the overflow system in conventional thickeners. In the existing thickener, an overflow system is generally designed on the premise that overflow is considered to be clear liquid, and the influence of a salt bloom layer on the surface of slurry is not considered. In the thickener chamber, the upper surface of the saturated solution is exposed in the thickener chamber, which is in continuous contact with the air in the thickener chamber, resulting in the continuous formation of salt bloom and gradual accumulation in the overflow system, eventually leading to plugging. Furthermore, the inlets of the overflow system for receiving slurry from the thickener chamber are all located at the level of the overflow or slightly below the overflow. Due to the thickness of the salt flower layer, even if the inlet is slightly lower than the overflow port, the relevant pipeline of the overflow system is still blocked, and the problems of heat waste and the like are further caused.

For example, in an overflow system such as that shown in fig. 1, the saturated solution overflowing from the thickener inner barrel carries a layer of salt bloom and the upper surface remains exposed to air during the downward flow to the right, continuing to generate salt bloom, causing losses, and eventually possibly causing salt bloom plugging in the pipe 15 or downstream thereof.

Figure 3 shows another prior art overflow system for a thickener without a breather valve. A similar structure is shown in patent application CN 201910583460.4. The overflow system comprises an overflow port 21 on the side wall of the thickener, and a mother liquid tank 25 arranged on the inner side of the overflow port 21, wherein the bottom of the mother liquid tank 25 is provided with a clear liquid communicating hole 24, and a space 22 enclosed by the mother liquid tank 25 and the side wall of the cavity of the thickener is communicated with other spaces 23 inside the thickener by crossing the top of the mother liquid tank 25. The mother liquor tank is configured to cooperate with a communicating bottle 26 outside the overflow port. The communication bottle 26 has a top air inlet 27 and a bottom clear liquid outlet 28 so that when overflowing, air from the external environment 29 can be introduced through the air inlet 27 and reach the thickener internal space 23 via the communication bottle 26, the overflow port 21, the space 22 to ensure the operation of the thickener is stable.

In operation of the overflow system, when the clear liquid in the space 22 overflows over the overflow 21, the clear liquid upper surface remains exposed to the head air in communication with the entire thickener headspace 23, so that the clear liquid surface may continue to produce a salt bloom and be lost with the overflow. Subsequently, during the overflow process, the solid salt of the salt bloom may block the overflow port 21.

Further, since the clear liquid communication hole 24 is also substantially at the height of the overflow port, when the liquid level is slightly low, salt of the salt bloom may accumulate in the vicinity of the clear liquid communication hole 24, resulting in clogging of the clear liquid communication hole 24. Therefore, the floating salt scraper is configured in the application, and the salt scraping is continuously rotated to avoid the blockage of the mother liquor tank. However, this design is complex and inefficient.

In summary, the existing overflow system not only has solid loss caused by salt bloom overflow, but also has the problem of blockage of related pipelines due to salt bloom layers.

a cavity with an inverted cone-shaped bottom part,

a slurry inlet located at the top of the chamber;

a slurry outlet at the bottom of the chamber;

a discharge valve located below the slurry outlet;

a discharge passage located below the discharge valve; and

it is characterized in that the preparation method is characterized in that,

Fig. 4 shows a schematic view of an embodiment of the thickener of the invention. The thickener comprises a chamber 41 with an inverted conical bottom, a slurry inlet 42 at its top and a slurry outlet 43 at its bottom, a discharge valve m below the slurry outlet, a discharge channel 45 below the discharge valve, an overflow opening 46 in the side wall between the top and the bottom of the chamber, and an in-chamber overflow pipe 47. The overflow pipe 47 in the cavity is connected at its upper end to the overflow port 46 and at its lower end is open at a level between the overflow port and the bottom. The figure also shows schematically a situation in which the slurry is filled, the slurry comprising a lower layer of deposited solids 48 and an upper layer of solution, the top surface 49 of which may be temporarily slightly higher than the level of the overflow 46, thereby driving the solution above the solids 48 in the middle of the chamber to overflow from the overflow 46 via the overflow 47 in the chamber. The thickener may also contain a breather valve 410 at the top and a service population 411.

When slurry is filled into the cavity of the thickener through the slurry inlet, the liquid level of the slurry in the cavity rises continuously, and the liquid level in the overflow pipe in the cavity also rises along with the slurry. When the slurry level in the cavity is slightly higher than the overflow port, the saturated solution in the overflow pipe in the cavity flows out from the overflow pipe. With the continuous filling of slurry into the thickener, the saturated solution continuously flows out, solid matters such as crystal salt are continuously deposited at the bottom of the cavity, and the accumulated upper surface of the deposit is continuously improved. And stopping continuously filling the slurry before the upper stacking surface reaches the lower end of the overflow pipe in the cavity. At this point, the solids fraction in the contents of the thickener is higher than the solids fraction in the charged feed slurry. And opening the discharge valve m, and discharging the content in the thickener, namely the thickened liquid, out of the cavity of the thickener.

The thickener is provided with an overflow pipe in the cavity, and the lower end of the overflow pipe is always immersed in salt water during operation. The crystal salt is generally precipitated on the surface and deposited at the bottom, so that the salt flowers precipitated on the surface cannot enter the overflow pipe. Because no separated salt bloom is lost from the overflow port, the problem of solid loss caused by a salt bloom layer on the surface of the slurry can be solved. In addition, the problem of clogging of the overflow system can be solved. The inlet of the overflow pipe in the chamber takes saturated solution from a position remote from the upper surface of the slurry, so that the layer of salt bloom created at the surface of the solution does not enter the overflow pipe in the chamber. The overflow pipe separates the overflow solution from the top gas in the cavity of the thickener, so that the slurry in the overflow pipe is not influenced by the low-temperature air in the thickener to generate salt bloom. And once the overflow is started, the overflow pipe in the cavity is filled with slurry, and no new salt bloom is formed. Therefore, the overflow system of the thickener of the invention is different from the prior structures such as fig. 2 and fig. 3, salt bloom is not easy to lose, and the blockage caused by the formation of a salt bloom layer is not easy to occur.

The upper and lower ends of the overflow tube within the cavity are referred to as its upper and lower ports, respectively. The overflow tube in the chamber between the upper and lower ends may be of any suitable shape, such as a curved tube, a straight tube, or a combination thereof, so long as the level of the saturated solution is not prevented from rising within the overflow tube in the chamber. The overflow pipe in the chamber preferably has no portion above its upper end so that overflow can begin when the liquid level reaches the level of the overflow opening. The lower end of the overflow tube in the chamber is preferably open downwardly to avoid solids deposition in the tube to the maximum extent possible.

The lower end of the overflow pipe in the cavity is far away from the overflow port as far as possible, but not lower than the upper surface of the expected solid sediment. Preferably, the volume of said cavity at the height between the lower end of the overflow pipe in the cavity and the overflow opening is more than 30%, more preferably 50%, still more preferably 70% of the volume of said cavity at the height between the bottom of said cavity and the overflow opening. Such a height ensures that a space large enough to accommodate the saturated solution is provided between the distance between the lower end inlet of the overflow pipe in the cavity and the slurry liquid level, so as to avoid the salt-flower layer on the surface of the saturated solution from influencing the overflow system. Accordingly, the saturated solution volume content of the resulting discharged slurry is preferably at least 30%, more preferably 50%, still more preferably 70%. When the slurry obtained from the thickener is further concentrated by, for example, a centrifuge as described below, the solids content thereof should not be too high, i.e., it should contain sufficient saturated solution. At least 70% by volume of the saturated solution, calculated from the density of the conventional saturated salt solution and salt solids, ensures that the solids content of the chamber does not exceed about 50% by weight when the upper surface of the solids deposited at the bottom of the chamber does not reach the height of the lower end of the overflow tube within the chamber.

In one embodiment, the discharge channel is connected to a centrifuge. In other words, the thick liquor is subsequently further separated from the liquid by means of a centrifuge. It is well known in the art that there is a maximum feed solids allowable by the centrifuge as one weight percent. When the feed solids content of the centrifuge is greater than this maximum feed solids content, the centrifuge is difficult to operate properly. At this point, the nominal maximum solids content of the thickener of the present invention preferably needs to be less than the maximum feed solids content allowed by the centrifuge. When the nominal maximum solids content of the thickener of the invention is less than the maximum feed solids content allowed for the centrifuge, failure of the centrifuge due to too high a feed solids content can be avoided.

The nominal maximum solids content β of the thickener is calculated by:

wherein the content of the first and second substances,

ρ₁the density of the solid matter is the density of the solid matter,

v₁in order to be the nominal bulk volume,

ρ₂the density of the clear liquid is the density of the clear liquid,

v is the volume of the cavity of the thickener below the overflow port,

wherein the nominal packing volume is a volume of the cavity between a lower end of the overflow tube within the cavity and a bottom of the cavity.

In the formula, the density and the volume are both in units, and may be, for example, g/cm, respectively³And cm³. For example, a common NaCl salt, has a density of about 2.13g/cm³The density of the clear solution (saturated solution) was about 1.2g/cm³。

In other words, β is the amount of solids deposited in the cavity of the thickener when the surface of the solid accumulation reaches the lower end of the overflow pipe in the cavity, assuming that the upper surface of the solid accumulation is planar. The solid matter may be precipitated salt, and the clear solution may be a saturated solution containing no solid matter.

Nominal maximum solids content and nominal bulk volume mean that there may be some deviation from the actual value due to the fact that the upper surface of the solids packing is non-planar in nature. In any event, it is necessary to ensure that the lower end of the overflow pipe in the chamber is not blocked by the solids accumulation.

The shape of the upper surface of the solid heap may be controlled by the shape of the inverted conical portion of the cavity. Preferably, the cone apex angle of the inverted cone is 30 ° to 90 °. The design angle of the cone body of the thickener can be obtained according to the accumulation angle experiment of salt. The stacking angle experiment measures the shape of the upper surface of the stacked solids at different cone apex angles. For example, when the bottom surface is flat, the solids accumulated at the bottom will form a cone with a high center and a low circumference. According to the accumulation angle experiment, the inventor finds that the angle alpha of the cone vertex angle is smaller than 90 degrees so as to avoid that the solid below the slurry inlet forms a positive cone shape and the accumulation height difference relative to the periphery is too large. It is also contemplated that the thickener volume will decrease as the angle decreases, and therefore, it is preferred that the angle be greater than 30 degrees. In addition, within the range, a relatively flat upper surface of the solid accumulation can be formed, and the lower end of the overflow pipe in the cavity of the invention can be prevented from being possibly blocked due to the high local accumulation.

Preferably, the diameter of the discharge channel is larger than the slurry outlet. In the prior art, the discharge valve is installed in the discharge pipeline, namely the diameters of the discharge pipeline before and after the discharge valve are unchanged, so the slurry discharge capacity before and after the discharge valve is the same. This causes the thick ware crystallization salt to centrifuge salt discharge pipeline often blocks up, needs the operation personnel to beat the mediation, is unfavorable for long-term continuous stable operation. The invention aims at the problem of salt discharge port blockage, designs the diameter of the discharge channel, and does not need a straight pipe salt discharge port. The diameter of the discharge channel is larger than the slurry outlet, and the discharge channel is equivalent to an amplifier. The amplifier is an enlarged spatial volume to avoid clogging. Preferably, the outlet channel has a caliber which is more than twice the caliber of the slurry outlet, i.e. an area which is more than four times the caliber, and clogging can generally be substantially avoided. The caliber of the discharging channel does not need to be too large, so that excessive consumption of materials and occupation of space are avoided.

Preferably, the discharge channel is connected to a centrifuge, the inlet opening of which is located directly below the discharge channel. Thus, solids such as salt entering the discharge channel will fall vertically under gravity to the centrifuge and will not adhere to the channel walls. This in effect avoids the use of a discharge conduit downstream of the discharge valve, ensuring that the slurry discharge capacity downstream of the discharge valve is higher than the slurry discharge capacity of the slurry outlet. The occurrence of clogging is avoided. Specifically, a discharge valve (such as a salt discharge valve) is arranged as close to a slurry outlet of the cone body of the thickener as possible, and an amplifier is directly connected behind the discharge valve.

Although the discharge channel design of the present invention can effectively avoid plugging problems in the piping downstream of the discharge valve, plugging problems at the slurry outlet and the discharge valve are still unavoidable. In the prior art, a pipeline is flushed by using process water, but the water quality of the process water is complex, and the salt quality can be reduced by frequent flushing and dredging. Preferably, the thickener of the present invention further comprises a dilute solution washing device. The dilute solution wash device is configured to provide dilute solution to the slurry outlet and/or the discharge valve.

The dilute solution cleaning device provides dilute solution for the slurry outlet and/or the discharge valve, and can dissolve and dredge. The dilute solution is a low concentration solution of the thickener treated slurry material, which may for example be taken directly from the dilute solution upstream of the evaporator. The use of dilute solutions can avoid the problem of impurities resulting from the cleaning of the process water. When the dilute solution cleaning device piece is provided with a pump or other pressurizing devices, the dilute solution cleaning device piece can also play a role in impact dredging. The slurry inlet can be directly used as a dilute solution cleaning device to introduce dilute solution. The dilute solution cleaning device may also have suitable separate reservoirs, conduits, nozzles and other pressurizing or accelerating means to effect the dissolution and/or impact unblocking. The nozzle may be disposed adjacent the outlet.

The high-temperature solution is in the thickener, and the heat in the air can be directly dissipated and not utilized, and the hidden danger of scalding can exist. Preferably, the side wall of the cavity has a hollow heat recovery wall cavity therein, the heat recovery wall cavity having a fluid inlet and a fluid outlet opening outside the side wall, wherein the fluid outlet is higher than the fluid inlet.

Figure 5 shows a heat recovery wall cavity in a cavity of the invention. A heat recovery wall cavity 51 surrounds the thickener cavity and has a lower fluid inlet 52 and an upper fluid outlet 53. Thus, when the low-temperature fluid enters the heat recovery wall cavity 51 from the fluid inlet 52 and leaves from the fluid outlet 53, the fluid exchanges heat with the wall of the cavity, so that the heat of the high-temperature solution in the thickener is recycled, and the saturated solution can be cooled to deposit more solids. The bottom-in and top-out flow path enables the low-temperature fluid to be heated gradually, and can also ensure that the heat recovery wall cavity is filled with the fluid. Conventionally, water is used as the heat recovery fluid. The outlet water temperature can be adjusted according to the process water flow. The heated water can be used to formulate medicaments to increase the solubility of the medicaments, as a source of hot water, for heating, and the like. A pump may be used to drive the operation of the heat recovery fluid. The heat recovery wall cavity may be any cavity shape, such as a single layer cavity or a spiral cavity surrounding the cavity. The outlet conduit diameter may preferably be more than 1.2 times the inlet conduit diameter to facilitate flow.

Preferably, the headspace of the chamber has a breather valve. The breather valve is used for adjusting the air pressure in the top space in the cavity of the thickener. Due to the overflow pipe in the cavity, when the upper surface of the slurry is higher than the lower end of the overflow pipe in the cavity, the air in the cavity of the thickener can not be discharged from the overflow port any more. Thus, if the feed port is not sufficient to adequately discharge air, an internal air pressure regulating device may be required. Among them, the breather valve is preferable because the setting is simple and sufficient. The breather valve is positioned in the headspace, which may be on the top surface or on a side wall near the top surface, above the overflow port. Thus, even if the overflow port only functions as an overflow, and does not function as a gas inlet/outlet, there is no concern about the problem of maintaining pressure.

Examples

The used thickener had a cavity having the shape shown in fig. 6, and the cone apex angle α of the inverted cone portion at the lower portion thereof was 38 °, and the height h4 of the inverted cone portion was 2.0 m. The height h1 of the overflow port is 1.8m, and the volume of the cavity below the overflow port (namely the volume corresponding to the height h 1) is 0.73m³. The inner diameter of the overflow pipe in the cavity is phi 80mm, the height h2 of the lower end is 1.6m, and the volume of the cavity below the lower end of the overflow pipe is 0.48m³The volume of the cavity between the lower end of the overflow pipe and the overflow port (i.e. the volume corresponding to the height difference between h1 and h 2) is 0.25m³. The diameter from the slurry outlet at the bottom to the centrifuge is phi 80mm, and the diameter of the discharge channel at the downstream of the discharge valve is phi 180 mm. A feed inlet of the centrifuge is arranged right below the discharge channel. The maximum feed solids content of the centrifuge was about 40%. The chamber side wall has a heat recovery wall cavity therein, with the fluid inlet i and outlet o located at a height of 0.7m and 1.65m respectively.

Slurry inlet from top of thickener at 20m³Filling NaCl saturated salt solution slurry from the evaporator at a speed of about 20% and a density of 1.2g/cm³And an intermittent feeding mode is adopted according to the amount of the salt precipitated from the crystallizer. The slurry level rises until it begins to overflow the overflow port. The overflow solution was returned to the evaporator. After the slurry is filled, the height h3 of the bottom solid layer is about 1.0m and is lower than the lower end of the overflow pipe in the cavity, and the volume of the solid in the cavity of the thickener is about 0.13m³And the weight content is 27.7 percent, which meets the maximum feeding solid content of a centrifuge.

During the operation, water with the temperature of 20 ℃ is filled from the fluid inlet of the heat recovery wall cavity for heating, and water with the temperature of about 50 ℃ is obtained from the fluid outlet.

And opening the discharge valve to enable the contents in the thickener to fall into the centrifuge. Centrifugation was carried out to finally obtain a product having a water content of 7.4% by weight.

The discharge port and discharge valve were continuously cleaned as described above using a dilute solution (6% concentration) cleaning device from upstream of the evaporator.

After 192 hours of operation as above, accumulation and clogging of crystalline salts were not found in the overflow system and the discharge passage, indicating that the thickener of the present invention is excellent in continuous operability. Compared with the conventional thickener with the same processing capacity, the thickener has high discharge concentration, which indicates that the thickener effectively avoids solid loss caused by salt bloom discharged along with overflow. In addition, the thickener system of the invention also provides hot water from the heat recovery wall cavity and avoids the risk of wall-induced scalding.

The thickener provided by the invention is provided with an intracavity overflow pipe, so that solid loss caused by salt bloom overflow can be reduced, and pipeline blockage caused by salt bloom can be relieved. The thickener of the invention is beneficial to long-time efficient and stable operation. In addition, the thickener can prevent the blockage of the discharge pipeline. The thickener of the invention can also effectively utilize heat and prevent operators from being scalded.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A thickener for separating saturated solution and solids contained in a slurry, the thickener comprising:

a cavity with an inverted cone-shaped bottom part,

a slurry inlet located at the top of the chamber;

a slurry outlet at the bottom of the chamber;

a discharge valve located below the slurry outlet;

a discharge passage located below the discharge valve; and

it is characterized in that the preparation method is characterized in that,

2. The thickener of claim 1 wherein,

the volume of the cavity with the height between the lower end of the overflow pipe in the cavity and the overflow port is more than 30% of the volume of the cavity with the height between the bottom of the cavity and the overflow port.

3. The thickener of claim 1 wherein,

the discharge channel is connected to a centrifuge and

wherein the content of the first and second substances,

ρ₁is the density of the solid material in question,

v₁in order to be the nominal bulk volume,

ρ₂the density of the clear solution;

v is the volume of the cavity of the thickener below the overflow port,

4. The thickener of claim 1 wherein,

the cone apex angle of the inverted cone is 30-90 degrees.

5. The thickener of claim 1 wherein,

the caliber of the discharge channel is larger than that of the slurry outlet.

6. The thickener of claim 5 wherein,

the discharge channel is connected to a centrifuge, and a feed inlet of the centrifuge is positioned under the discharge channel.

7. The thickener of claim 1 wherein,

the thickener also has a dilute solution wash device configured to provide dilute solution to the slurry outlet and/or the discharge valve.

8. The thickener of claim 1 wherein,

the side wall of the cavity has a hollow heat recovery wall cavity therein having a fluid inlet and a fluid outlet opening outside the side wall, wherein the fluid outlet is higher than the fluid inlet.

9. The thickener of claim 1 wherein,

the headspace of the chamber has a breather valve.