A multi-stage mixing device and method for solid fuel and liquid medium

Abstract

The present invention discloses a multi-stage mixing device and method for solid fuel and liquid medium, the device comprising: an inner sleeve (1); an outer sleeve (2), the inner sleeve (1) and the outer sleeve (2) being connected and fixed by a bracket (9); a solid fuel slurry inlet (41), the solid fuel slurry inlet (41) being coaxial with the inner sleeve (1); an air inlet (42); a micro-nano bubble generating component (5); and a material outlet (71). The multi-stage mixing device of the present invention can pre-mineralize solid fuel particle materials separately before a flotation separation device, thereby improving the mineralization degree of solid fuel particles. The higher the mineralization degree, the better the flotation separation effect in the subsequent foam flotation tower, which is reflected in the more obvious phase interface between the foam phase and the water phase in the foam flotation tower, and also avoids the problem of a large number of mineral particles being mixed in the carbon-hydrogen combustible particles in a single tank flotation device. The multi-stage mixing device of the present invention can also be used to prepare a suspended stable liquid-like fuel.

Description

Technical Field

[0001] The invention belongs to the field of mixing equipment, and in particular relates to a multi-stage mixing device for solid fuel and liquid medium and an operating method thereof. Background Art

[0002] Mixing is a common unit operation in chemical, chemical and wet mineral processing. In the mixing operation, the most difficult part is how to evenly mix the three phases of gas, liquid and solid into a stable "quasi-liquid" so that it can be transported by pumps and intensified for specific operations, such as full contact between the three phases of gas, liquid and solid. Due to the huge differences in the density of gas, liquid and solid and the surface hydrophilicity / hydrophobicity, conventional stirring paddles or impeller high-speed stirring mixing often cannot obtain a uniform and stable three-phase mixture, which is manifested in the fact that solids are easy to settle and microbubbles are easy to quickly gather into large bubbles and escape. Whether it is solid sedimentation or bubble escape, it will cause the slurry to become unstable and no longer be a "quasi-liquid slurry", losing pumpability or reducing the contact between the three phases of gas, liquid and solid.

[0003] For example, in the coal chemical industry, low-quality coal powder doped with mineral particles is usually subjected to froth flotation technology to remove mineral particles. The resulting ultra-fine, ultra-low ash clean coal powder slurry is then used to prepare water-coal slurry with a specific combustible fuel concentration and supplied to the coal gasification device. The froth flotation process requires the solid particles (including coal powder and mineral particles), liquid medium (water or oil) and gas (microbubbles) to be fully mixed into a "quasi-liquid" in three phases to facilitate pumping and enhance the froth flotation effect. This is just a typical application scenario for gas-liquid-solid three-phase mixing, and there are of course other application scenarios.

[0004] In summary, the industry has always hoped to have a device and method that can fully and evenly mix solid fuel particles, liquid medium and microbubbles into a stable "liquid-like slurry". The present invention is intended to solve this technical problem. Summary of the invention

[0005] A first aspect of the present invention provides a multi-stage mixing device for solid fuel and liquid medium, comprising:

[0006] An inner sleeve 1, wherein the inner sleeve 1 has inner sleeve holes 11 distributed circumferentially;

[0007] An outer sleeve 2, which is located outside the inner sleeve 1, and the inner sleeve 1 and the outer sleeve 2 are connected and fixed by a bracket 9;

[0008] A solid fuel slurry inlet 41 connected to the upstream of the inner sleeve 1, wherein the solid fuel slurry inlet 41 is coaxial with the inner sleeve 1;

[0009] An air inlet 42 connected to the upstream of the inner sleeve 1, wherein the angle between the air inlet 42 and the solid fuel slurry inlet 41 is 30° to 60°;

[0010] A micro-nano bubble generating component 5, which is located downstream of the inner sleeve 1;

[0011] The material outlet 71 is connected to the inner sleeve 1 downstream.

[0012] Preferably, there are multiple air inlets 42; a gas distribution porous plate 421 is provided on the air inlet 42, and the gas distribution porous plate 421 is a porous structure formed by compressing metal powder.

[0013] Preferably, an upstream fixing seat 3 is provided upstream of the outer sleeve 2, and the seat has a first cavity 31; a base 4 is provided upstream of the upstream fixing seat 3, and the base 4 has a second cavity 43 and the air inlet 42, and the first cavity 31 and the second cavity 43 are isosceles trapezoids, and the side close to the solid fuel slurry inlet 41 is the upper base of the isosceles trapezoid.

[0014] Preferably, the first cavity 31 , the second cavity 43 and the solid fuel slurry inlet 41 are coaxially connected, and the air inlet 42 is connected to the second cavity 43 .

[0015] Preferably, a downstream fixing seat 6 is provided downstream of the outer sleeve 2, which has a third cavity 61; an outlet fixing seat 7 is provided downstream of the downstream fixing seat 6, which has a material channel 72 and the solid fuel slurry outlet 71, and the third cavity 61, the material channel 72 and the solid fuel slurry outlet 71 are connected.

[0016] Preferably, a top cover 8 is provided downstream of the outlet fixing seat 7 .

[0017] Preferably, the inner sleeve 1, the outer sleeve 2, the upstream fixing seat 3, the base 4, the micro-nano bubble generating component 5, the downstream fixing seat 6, the outlet fixing seat 7 and the top cover 8 are coaxial.

[0018] Preferably, the micro-nano bubble generating component 5 comprises a head portion 51 and a rod portion 52 which are coaxially connected, and the rod portion 52 comprises a rotating shaft 521 and a rod wall 522 outside the rotating shaft 521;

[0019] The head 1 comprises:

[0020] a paddle 511 connected to a distal end of the rotating shaft 521, wherein the paddle 511 extends radially and axially away from the rotating shaft 521;

[0021] A housing 512, which is located at the periphery of the blade 511 and includes a plurality of housing teeth 5121 and housing tooth holes 5122 between adjacent housing teeth 5121;

[0022] There is a gap 53 between the housing teeth 5121 and the blades 511 .

[0023] Among them, the radial distance of the gap 53 is 0.2~3mm, the number of the blades 511 is N, N≥2, the outer edge of the blade 511 is a curved surface, and as the blade 511 extends, the area of ​​the curved surface decreases, the number of the shell tooth holes 5121 is N, N≥2, the shell tooth holes 5121 are evenly distributed along the circumference of the shell 512, and there is a gap between the rotating shaft 521 and the rod wall 522, so that the rotating shaft 521 drives the blade 511 to rotate circumferentially in a clockwise or counterclockwise direction, the linear speed of the outer edge of the blade 511 is 10~50m / s, the contact surface between the shell tooth hole 5122 and the shell tooth 5121 is inclined along the rotation direction of the rotating shaft 521, and the diameter of the head 51 is larger than the diameter of the rod 52.

[0024] The second aspect of the present invention provides an operating method of the multi-stage mixing device of solid fuel and liquid medium, which comprises the following steps:

[0025] (1) A solid fuel slurry containing solid fuel particles and a liquid medium enters the second cavity 43 from the solid fuel slurry inlet 41 and is mixed with the air entering from the air inlet 42. Preferably, the Reynolds number of the air here is 2000 to 5000. Since the air inlet 42 and the solid fuel slurry inlet 41 are not arranged in parallel, the material and the air form a rotating turbulent flow in the second cavity 43 and complete the first turbulent mixing.

[0026] (2) The blades 511 in the microbubble generating component 5 rotate to generate suction, causing the mixture of material and air to be sucked into the inner sleeve 1, the turbulence in the inner sleeve 1 is enhanced, and the material and air complete a second turbulent mixing in the inner sleeve 1;

[0027] (3) The mixture of material and air further enters the microbubble generating component 5, and the blade 511 of the microbubble generating component 5 rotates, causing the material and air to undergo a third turbulent mixing. At the same time, the outer edge linear velocity of the blade 511 is 10 to 50 m / s. The air is repeatedly cut by the rotating blade 511, and the shear force provided by the outer shell teeth 5121 and the blade 511 is formed to form micro-nano bubbles. At this time, the diameter of the micro-nano bubbles is 0.1 to 1000 microns. The surface of the carbon-hydrogen-containing combustible particles in the solid fuel particles adheres to the micro-nano bubbles. Then, a part of the mixture of material and air enters the annular gap between the inner sleeve 1 and the outer sleeve 2, and then enters the inner sleeve 1 through the inner sleeve hole 11 on the inner sleeve 1 to continue mixing. The other part of the mixture of material and air passes through the material channel 72 and is discharged from the material outlet 71.

[0028] Preferably, the residence time of the mixture of material and air in the multi-stage mixing device is 1 to 5 minutes.

[0029] The method of the second aspect of the present invention can be used to perform a pre-mineralization operation of solid fuel particles in a liquid medium, wherein the solid fuel in step (1) is low-quality coal having an ash content higher than 30 wt%, and a mineralizing agent is added to the solid fuel slurry, wherein the mineralizing agent includes one or more of an additive, a surface cleaning agent, a collector, a foaming agent, an inhibitor, and a flocculant, and the additive is selected from aluminosilicate nanoparticles.

[0030] The method of the second aspect of the present invention can also be used to prepare a suspended stable liquid fuel, in which case the solid fuel particles in step (1) are low ash ultrafine carbonaceous particles, wherein the low ash content means that the mineral content in the carbonaceous particles is less than 5wt%, and the ultrafine means that the particle size of the carbonaceous particles is 0.1 to 50 microns, and the liquid medium includes fuel oil, alcohol, ether, water or a mixture thereof, and a solid particle surface modifier is added to the solid fuel slurry, wherein the solid particle surface modifier includes a dispersant and a stabilizer. The dispersant is selected from: anionic surfactants, nonionic surfactants or their composites, wherein the anionic dispersant is selected from lignin sulfonates, naphthalene sulfonates, olefin sulfonates and polymers, and the nonionic dispersant is selected from polyoxyethylene ethers and polyoxyethylene block polyether surfactants; the stabilizer is selected from soluble salts, carboxymethyl cellulose, hydroxyethyl cellulose or polyacrylamide.

[0031] The low-ash ultrafine carbonaceous particles are obtained by crushing low-ash high-quality coal, or by performing a pre-mineralization operation on solid fuel particles in a liquid medium, and then subjecting the product to froth flotation, and removing the froth from the top material of the froth flotation tower.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The multi-stage mixing device of the present invention does not use a Venturi high-speed mixing device to perform the first mixing of the material and the air. Instead, it utilizes the angle set between the air inlet 42 and the solid fuel slurry inlet 41 to allow the air to enter the second cavity 43 to form a rotating turbulent flow, and further complete the first turbulent mixing with the material. This method can not only introduce high-speed rotating air into the device, prompting it to complete the first turbulent mixing with the material, but also avoid the wear of the device by the high-speed rotating air.

[0034] 2. The angle between the air inlet 42 of the present invention and the central axis of the inner sleeve 1 is 10° to 50°, which prevents the sinking mortar of the inner sleeve 1 from blocking the air inlet 42. At the same time, the air inlet 42 of the present invention is provided with a gas distribution porous plate 421, which can further prevent the sinking mortar from blocking the air inlet 42, but it will not block the air. At the same time, the gas distribution porous plate 421 can also take into account the role of a gas distributor, and the air entering the second cavity 43 through the gas distribution porous plate 421 can reach tens to hundreds of microns.

[0035] 3. The material and air in the pre-mineralization device of the present invention undergo three turbulent mixings in total, and the one high-speed rotating mixing is improved into three mixings, which not only ensures that the material and air are fully mixed at an appropriate turbulence under the condition of low input energy, so that the air and the mineralizing agent are fully adhered to the hydrophobic carbon-hydrogen-containing combustible particles, that is, the solid fuel slurry is fully mineralized, but also the wear of the device by the air is avoided.

[0036] 4. The outer periphery of the paddle 511 of the micro-nano bubble generating component 5 of the present invention is provided with a shell 512, and the paddle 511 rotates in the narrow space defined by the shell 512. At the same time, there is a gap 53 between the shell teeth 5121 on the shell 512 and the paddle 511. During the rotation of the paddle 511, the gas is not only repeatedly cut by the rotating paddle 511, but also subjected to the shear force provided by the shell teeth 5121 (equivalent to the stator) and the paddle 511 (equivalent to the rotor). When the rotation speed of the rotating shaft 521 of the micro-nano bubble generating device of the present invention is 8000rpm, bubbles with a size of 1 to 50 microns are obtained, the bubble size is controllable, and the bubble residence time in the liquid is long.

[0037] 5. The micro-nano bubble generating component 5 in the present invention can not only make the material and air undergo a third turbulent mixing, but also can shear the air into a large number of micro-nano bubbles. The multi-stage mixing device of the present invention does not need to be connected to a micro-bubble generator. At the same time, after the micro-nano bubbles adhere to the surface of the carbon-hydrogen-containing combustible particles in the solid fuel slurry, it is easier to adhere to the large bubbles in the micro-mineral separation tower in the subsequent separation process. The carbon-hydrogen-containing combustible particles have a high bonding rate with the bubbles and are firmly bonded.

[0038] 6. The multi-stage mixing device of the present invention can pre-mineralize the solid fuel particle material separately before the flotation separation device, which not only improves the mineralization degree of the solid fuel particles, where the mineralization degree refers to the separation degree of solid fuel particles and mineral particles and the combination degree of solid fuel particles and bubbles. The higher the mineralization degree, the better the flotation separation effect in the subsequent froth flotation tower, which is reflected in the more obvious interface between the froth phase and the water phase in the froth flotation tower. It also avoids the problem of a large number of mineral particles mixed in the carbon-hydrogen combustible particles in the single-tank flotation device.

[0039] 7. The multi-stage mixing device of the present invention can also be used to prepare a quasi-liquid fuel with stable suspension. Since the water-coal slurry and the fuel oil are mixed intensively in multiple stages, the emulsification is promoted, and the stability of the coexistence of water and oil is improved. The multi-stage mixing device of the present invention also produces stable nano-micron bubbles and adsorbs them around the low-ash ultrafine carbonaceous particles, which improves the suspension stability of the solid particles in the liquid medium. The combined stabilization effect of the two allows the obtained quasi-liquid fuel to remain suspended stably for up to 30 days. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the multi-stage mixing device of the present invention

[0041] Figure 2 Schematic diagram of the structure of the base 4 in the multi-stage mixing device of the present invention

[0042] Figure 3 Cross-sectional view of the micro-nano generating component 5 in the multi-stage mixing device of the present invention

[0043] Figure 4 Bottom view of the micro-nano generating component 5 in the multi-stage mixing device of the present invention

[0044] Figure 5 Process flow chart of the embodiment of the present invention

[0045] The names of the reference numerals in the drawings are: 1-inner sleeve, 2-outer sleeve, 3-upstream fixing seat, 4-base, 5-micro-nano bubble generating component, 6-downstream fixing seat, 7-outlet fixing seat, 8-top cover, 9-bracket, 11-inner sleeve hole, 31-first cavity, 41-solid fuel slurry inlet, 42-air inlet, 43-second cavity, 51-head, 52-rod, 53-gap, 71-solid fuel Slurry outlet, 72-material channel, 511-blade, 512-housing, 521-rotating shaft, 522-rod wall, 5121-housing teeth, 5122-housing tooth holes, 1111-feed buffer tank, 2222-feed pump, 3333-multi-stage mixing device, 4444-static mixer, 5555-type distributor, 6666-micro-ore separation tower, 7777-top flow clean coal tank, 8888-bottom flow collection tank. DETAILED DESCRIPTION

[0046] The present invention is further described below by way of examples, but the present invention is not limited thereto.

[0047] Example 1

[0048] This embodiment is a multi-stage mixing device, which includes:

[0049] An inner sleeve 1, wherein the inner sleeve 1 has inner sleeve holes 11 distributed circumferentially;

[0050] An outer sleeve 2, which is located outside the inner sleeve 1, and the inner sleeve 1 and the outer sleeve 2 are connected and fixed by a bracket 9;

[0051] A solid fuel slurry inlet 41 connected to the upstream of the inner sleeve 1, wherein the solid fuel slurry inlet 41 is coaxial with the inner sleeve 1;

[0052] An air inlet 42 connected to the upstream of the inner sleeve 1, wherein the angle between the air inlet 42 and the solid fuel slurry inlet 41 is 58°;

[0053] A micro-nano bubble generating component 5, which is located downstream of the inner sleeve 1;

[0054] A material outlet 71 connected to the downstream of the inner sleeve 1;

[0055] There are two air inlets 42 ; each air inlet 42 is provided with a gas distribution porous plate 421 .

[0056] An upstream fixing seat 3 is arranged upstream of the outer sleeve 2, and has a first cavity 31; a base 4 is arranged upstream of the upstream fixing seat 3, and has a second cavity 43, the air inlet 42 and the air inlet 42, the first cavity 31 and the second cavity 43 are isosceles trapezoids, and the side close to the solid fuel slurry inlet 41 is the upper base of the isosceles trapezoid.

[0057] The first cavity 31 , the second cavity 43 and the solid fuel slurry inlet 41 are coaxially connected, and the air inlet 42 is connected to the second cavity 43 .

[0058] A downstream fixing seat 6 is provided downstream of the outer sleeve 2, and has a third cavity 61; an outlet fixing seat 7 is provided downstream of the downstream fixing seat 6, and has a material channel 72 and the solid fuel slurry outlet 71, and the third cavity 61, the material channel 72 and the solid fuel slurry outlet 71 are connected.

[0059] A top cover 8 is arranged downstream of the outlet fixing seat 7 .

[0060] The inner sleeve 1, the outer sleeve 2, the upstream fixing seat 3, the base 4, the micro-nano bubble generating component 5, the downstream fixing seat 6, the outlet fixing seat 7 and the top cover 8 are coaxial.

[0061] The micro-nano bubble generating component 5 comprises a head portion 51 and a rod portion 52 which are coaxially connected, and the rod portion 52 comprises a rotating shaft 521 and a rod wall 522 outside the rotating shaft 521;

[0062] The header 51 includes:

[0063] a paddle 511 connected to a distal end of the rotating shaft 521, wherein the paddle 511 extends radially and axially away from the rotating shaft 521;

[0064] A housing 512, which is located at the periphery of the blade 511 and includes a plurality of housing teeth 5121 and housing tooth holes 5122 between adjacent housing teeth 5121;

[0065] There is a gap 53 between the housing teeth 5121 and the blades 511 .

[0066] Among them, the radial distance of the gap 53 is 0.5mm, the number of the blades 511 is 3, the outer edge of the blade 511 is a curved surface, and as the blade 511 extends, the area of ​​the curved surface decreases, the number of the shell tooth holes 5121 is 14, and the shell tooth holes 5121 are evenly distributed along the circumference of the shell 512. There is a gap between the rotating shaft 521 and the rod wall 522, so that the rotating shaft 521 drives the blade 511 to rotate circumferentially in the counterclockwise direction, the linear velocity of the outer edge of the blade 511 is 40m / s, the contact surface between the shell tooth holes 5122 and the shell teeth 5121 is inclined along the rotation direction of the rotating shaft 521, and the diameter of the head 51 is larger than the diameter of the rod 52.

[0067] Example 2

[0068] This embodiment uses the multi-stage mixing device shown in Example 1 to carry out the pre-mineralization process of the water-coal slurry. The process flow chart is as follows: Figure 5 As shown, the multi-stage mixed pre-mineralization process and micro-ore separation process are as follows:

[0069] The low-quality coal used is peat with a mineral content of 30wt%, which is transported to a crusher for preliminary crushing and then introduced into a wet grinder to be ground to a particle size of less than 50 microns. The prepared solid fuel slurry is stored in a feed buffer tank 1111, and the amount of solid fuel slurry added is controlled by a solid fuel slurry weighing instrument. The solid fuel slurry is conveyed to the multi-stage mixing device 3333 at a pumping pressure of 0.3 MPa through the solid fuel slurry feed pump 2222 and the solid fuel slurry conveying pipeline. The pre-mineralizing agent is fully mixed with a small amount of water in the static mixer 4444 and enters the multi-stage mixing device 3333 together with the ore slurry, and is strongly mixed with the mineralizing agent, water and air turbulence, so that the surface of the fine particles is fully in contact with the mineralizing agent to achieve efficient pre-mineralization. The solid fuel particles, mineralizing agent and water enter the second cavity 43 from the solid fuel slurry inlet 41 and are mixed with the air entering from the air inlet 42. Since the air inlet 42 and the solid fuel slurry inlet 41 are not arranged in parallel, the material and air form a rotating turbulent flow in the second cavity 43 and complete the first turbulent mixing. The blades 511 in the microbubble generating component 5 rotate to generate suction, causing the mixture of material and air to be sucked into the inner sleeve 1. The turbulence in the inner sleeve 1 is enhanced, and the material and air complete the second turbulent mixing in the inner sleeve 1; the mixture of material and air further enters the microbubble generating component 5, and the blade 511 of the microbubble generating component 5 rotates, prompting the material and air to perform the third turbulent mixing. At the same time, the outer edge linear velocity of the blade 511 is 40m / s, and the air is repeatedly cut by the rotating blade 511, and the shear force provided by the outer shell teeth 5121 and the blade 511 forms micro-nano bubbles. At this time, the diameter of the micro-nano bubbles is 20 to 100 microns, and the micro-nano bubbles are adhered to the surface of the carbon-hydrogen-containing combustible particles in the solid fuel particles. Then, a part of the mixture of material and air enters the annular gap between the inner sleeve 1 and the outer sleeve 2, and then enters the inner sleeve 1 through the inner sleeve hole 11 on the inner sleeve 1 to continue mineralization, and the other part of the mixture of material and air passes through the material channel 72 and is discharged from the material outlet 71.

[0070] The material discharged from the multi-stage mixing device of the present invention enters the micro-mineral separation tower 6666 through the fractal distributor 5555. The fully mineralized hydrophobic particles in the solid fuel slurry have an increased probability of adhering to the rising bubbles due to the adhesion of micro-nano-scale air bubbles, making them float with a density lower than that of water, and forming a bubble layer at the top of the micro-mineral separation tower 6666. The bubble layer thickness ranges from 0.2m to 2m. The water in the bubble layer drops due to the action of gravity, and carries the hydrophilic minerals to sink, so that the clean coal concentration at the top of the bubble layer gradually increases and overflows from the top of the tower to form a top-flow clean coal product, and enters the top-flow clean coal tank 7777. The hydrophilic minerals in the coal slime sink with a density greater than that of water under the action of the selective flocculant, and the concentration of the minerals gradually increases under the action of the rising bubbles.

[0071] The hydrophobic substances entrained in the hydrophilic agglomerates are carried by the rising bubbles and separated from the hydrophilic substances and rise. Under the interaction of the reagents, bubbles and fine particles, a gradient of hydrophilic substance concentration is formed in the micro-mineral separation tower 6666, and this concentration increases as the position in the tower decreases. The slurry rich in hydrophilic substances discharged from the bottom of the tower then enters the underflow collection tank 8888, and the underflow flow rate is feedback-controlled by the height of the foam layer.

[0072] The mineralizing agent comprises one or more of an additive, a surface cleaning agent, a collector, a foaming agent, an inhibitor, and a flocculant, and the additive is selected from aluminosilicate nanoparticles.

[0073] The splitter 5555 is a new type of fluid distribution device. It can divide the main fluid into two equal parts each time and transport them the same distance, so that the two split fluids have the same flow rate and pressure distribution. The two split fluids thus generated are split again in the same way to obtain four split fluids with the same flow rate and pressure distribution. By analogy, the main fluid can be split into two n Distribute the fluid to form an absolutely uniform distribution.

[0074] It was found in the experiment that the material treated by the multi-stage mixing device of the present invention can form a very obvious interface between the foam phase and the water phase after entering the subsequent micro-mineral separator. This may be because after the micro-nano bubbles are pre-surrounded by the carbonaceous particles in the multi-stage mixing device, the micro-bubbles are easier to combine with the large bubbles than the surface of the carbonaceous particles. Therefore, after entering the micro-mineral separator, it is very easy to combine with the large bubbles introduced from the bottom, which promotes the foam flotation process. After removing the foam from the top product of the micro-mineral separation tower, it was found that it was ultra-fine low-ash carbonaceous particles with an ash content of 2.3%.

[0075] Comparative Example 2

[0076] use Figure 5 The same process equipment and layout as shown in the figure are used, but the multi-stage mixing device of the present invention is not used as the pre-mineralizer, but a conventional bubble stirring tank type pre-mineralizer is used, and the other process conditions are the same. In contrast, it can be seen visually that the interface between the foam phase and the water phase in the micro-mineral separator is blurred. After removing the foam from the top product of the micro-mineral separation tower, it was found that it was ultra-fine low-ash carbonaceous particles with an ash content of 4.1%.

[0077] Example 3

[0078] This embodiment uses the multi-stage mixing device of the present invention to prepare liquid fuel by mixing clean coal water slurry with oil.

[0079] The method comprises the following steps: selecting low ash clean coal with an ash content of less than 5 wt %, and wet grinding the clean coal in a water medium to obtain a clean coal water slurry with an average particle size of 5 microns and 90% of the particle size being less than 10 microns. At the same time, sodium naphthalenesulfonate is added as a dispersant and polyacrylamide is added as a stabilizer to the clean coal water slurry, and the solid content is 95 wt %.

[0080] Then the clean coal water slurry is mixed with heavy diesel oil, and the mixing ratio is based on the final slurry with a solid content of 30wt%. The mixture is passed through the multi-stage mixing device of the present invention for multi-stage mixing. Air is introduced during the mixing process. During the mixing process, the diesel oil is fully emulsified with water into a nearly uniform emulsified phase, and the air is also dispersed into micro-nano bubbles. The mixture from the multi-stage mixing device is loaded into a storage tank, and visually presents a uniform emulsified phase. Random sampling at multiple points in the storage tank is tested, and the solid content is in the range of 29% to 31%, indicating that the mixing is very uniform; after being stored for 30 days under ambient temperature and ambient pressure conditions, it is found that the carbonaceous particles are still stably suspended, and no hard precipitation occurs.

[0081] In contrast, after the clean coal powder water slurry was mixed with heavy diesel in a conventional mixing tank, visible sedimentation of the clean coal powder began to occur after only 7 days, and the coal powder was completely settled after 15 days.

Claims

1. A multi-stage mixing device for solid fuel and liquid medium, characterized in that: It includes: An inner sleeve (1), wherein the inner sleeve (1) has inner sleeve holes (11) distributed in a circumferential direction; An outer sleeve (2) located outside the inner sleeve (1), the inner sleeve (1) and the outer sleeve (2) being connected and fixed via a bracket (9); A solid fuel slurry inlet (41) connected to the upstream of the inner sleeve (1), wherein the solid fuel slurry inlet (41) is coaxial with the inner sleeve (1); An air inlet (42) connected to the upstream of the inner sleeve (1), wherein the angle between the air inlet (42) and the solid fuel slurry inlet (41) is 30° to 60°; A micro-nano bubble generating component (5), which is located downstream of the inner sleeve (1); A solid fuel slurry outlet (71) is connected to the inner sleeve (1) downstream.

2. The multi-stage mixing device of solid fuel and liquid medium according to claim 1, characterized in that: There are a plurality of air inlets (42); and a gas distribution porous plate (421) is provided on the air inlet (42).

3. The multi-stage mixing device of solid fuel and liquid medium according to claim 2, characterized in that: An upstream fixing seat (3) is arranged upstream of the outer sleeve (2), and has a first cavity (31); a base (4) is arranged upstream of the upstream fixing seat (3), and has a second cavity (43), the air inlet (42) and the solid fuel slurry inlet (41); the first cavity (31) and the second cavity (43) are isosceles trapezoids, and the side close to the solid fuel slurry inlet (41) is the upper base of the isosceles trapezoid.

4. The multi-stage mixing device of solid fuel and liquid medium according to claim 3, characterized in that: The first cavity (31), the second cavity (43) and the solid fuel slurry inlet (41) are coaxially connected, and the air inlet (42) is connected to the second cavity (43).

5. The multi-stage mixing device of solid fuel and liquid medium according to claim 4, characterized in that: A downstream fixing seat (6) is provided downstream of the outer sleeve (2), and has a third cavity (61); an outlet fixing seat (7) is provided downstream of the downstream fixing seat (6), and has a material channel (72) and the solid fuel slurry outlet (71); the third cavity (61), the material channel (72) and the solid fuel slurry outlet (71) are in communication.

6. The multi-stage mixing device of solid fuel and liquid medium according to claim 5, characterized in that: A top cover (8) is provided downstream of the outlet fixing seat (7); the inner sleeve (1), the outer sleeve (2), the upstream fixing seat (3), the base (4), the micro-nano bubble generating component (5), the downstream fixing seat (6), the outlet fixing seat (7) and the top cover (8) are coaxial.

7. The multi-stage mixing device of solid fuel and liquid medium according to claim 6, characterized in that: The micro-nano bubble generating component (5) comprises a head portion (51) and a rod portion (52) which are coaxially connected, and the rod portion (52) comprises a rotating shaft (521) and a rod wall (522) outside the rotating shaft (521); The head (51) comprises: a paddle (511) connected to the end of the rotating shaft (521), the paddle (511) extending in a direction away from the rotating shaft (521) in both the radial direction and the axial direction of the rotating shaft (521); A housing (512) located at the periphery of the blade (511), comprising a plurality of housing teeth (5121) and housing tooth holes (5122) between adjacent housing teeth (5121); There is a gap (53) between the housing teeth (5121) and the blades (511).

8. An operating method of the multi-stage mixing device of solid fuel and liquid medium according to claim 7, characterized in that: It includes the following steps: A. Allowing a solid fuel slurry containing solid fuel particles and a liquid medium to enter the second cavity (43) from the solid fuel slurry inlet (41) and to mix with the air entering from the air inlet (42). Since the air inlet (42) and the solid fuel slurry inlet (41) are not arranged in parallel, the material and the air form a rotating turbulent flow in the second cavity (43), and the first turbulent mixing is completed; B. The blades (511) in the micro-nano bubble generating component (5) rotate to generate suction, causing the mixture of the material and the air to be sucked into the inner sleeve (1), the turbulence in the inner sleeve (1) is enhanced, and the material and the air complete a second turbulent mixing in the inner sleeve (1); C. The mixture of material and air further enters the micro-nano bubble generating component (5), and the blade (511) of the micro-nano bubble generating component (5) rotates, causing the material and air to undergo a third turbulent mixing. At the same time, the outer edge linear velocity of the blade (511) is 5 to 50 m / s. The air is repeatedly cut by the rotating blade (511) and the shear force provided by the outer shell teeth (5121) and the blade (511), thereby forming micro-nano bubbles with a diameter of 0.1 to 1000 microns. The surfaces of the carbon-hydrogen-containing combustible particles in the solid fuel particles adhere to the micro-nano bubbles. Then, a portion of the mixture of material and air enters the annular gap between the inner sleeve (1) and the outer sleeve (2), and then enters the inner sleeve (1) through the inner sleeve hole (11) on the inner sleeve (1) to continue mixing and particle surface modification. Another portion of the mixture of material and air passes through the material channel (72) and is discharged through the solid fuel slurry outlet (71).

9. The method according to claim 8, characterized in that The method is used to perform a pre-mineralization operation of solid fuel particles in a liquid medium. At this time, the solid fuel in step (1) is low-quality coal with an ash content higher than 30wt%, and a mineralizing agent is also added to the solid fuel slurry. The mineralizing agent includes one or more of an additive, a surface cleaning agent, a collector, a foaming agent, an inhibitor, and a flocculant, and the additive is selected from aluminosilicate nanoparticles.

10. The method according to claim 8, characterized in that The method is used to prepare a suspended stable liquid-like fuel, in which the solid fuel particles in step (1) are low-ash ultrafine carbonaceous particles, wherein the low ash content means that the mineral content in the carbonaceous particles is less than 5wt%, and the ultrafine means that the particle size of the carbonaceous particles is 0.1 to 50 microns. The liquid medium includes fuel oil, alcohol, ether, water or a mixture thereof, and a solid particle surface modifier is added to the solid fuel slurry, wherein the solid particle surface modifier includes a dispersant and a stabilizer.

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