A Venturi-type multiphase fluid mixer and a multiphase fluid mixing method

Abstract

The present invention discloses a Venturi-type multiphase fluid mixer and a material mixing method, which include: a sleeve (1), an upstream converging pipe (2), a downstream diverging pipe (3), a multiphase fluid mixing chamber (4), and a feed pipe (5); the surface pressure at the multiphase fluid mixing chamber (4) is -0.01 MPa to +0.01 MPa; the multiphase fluid mixing includes gas-liquid, gas-liquid-solid, liquid-liquid, and liquid-liquid-solid mixing; the cross-sectional area of the multiphase fluid mixing chamber (4) is larger than the cross-sectional area of the throat. Since the hydrostatic pressure of the fluid at the multiphase fluid mixing chamber (4) is slightly negative pressure to slightly positive pressure and is easy to control, the pressure at the throat is not affected by downstream equipment or pipelines, and the pressure is stable. A positive pressure supply device is used to introduce a second material into the multiphase fluid mixing chamber (4). Since the positive pressure of the positive pressure supply device can be stably controlled, the amount of the second material introduced into the multiphase fluid mixing chamber (4) can also be stably controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas-liquid mixers, and particularly relates to a Venturi-type multiphase fluid mixer capable of stably controlling gas flow rate and a multiphase fluid mixing method. Background Art

[0002] With the rapid development and wide application of large-scale mechanized coal mining technology, during the coal mining process, coal gangue will be refined, and more fine-grained clay minerals will be mixed. Mechanical coal mining equipment cannot effectively distinguish between coal seams and gangue layers during operation, resulting in a large amount of fine clay mineral particles and fine coal particles in the mined coal. In addition, coal itself inevitably contains associated minerals (such as kaolinite, feldspar, silica, etc.), especially low-quality coal, which has a higher content of mineral impurities. When the above-mentioned coal is pulverized and slurried to make coal water slurry, a large amount of mineral impurities are naturally entrained, affecting the calorific value of the coal water slurry, and it is necessary to remove the minerals.

[0003] The foam flotation process is a commonly used method for removing mineral impurities. In the flotation column, hydrophobic carbonaceous particles are easy to adhere to bubbles and float with the bubbles, while hydrophilic mineral particles sink, thereby removing mineral impurities. Before entering the foam flotation column, it is often necessary to pre-mix the coal water slurry and air in a certain proportion and then introduce them into the flotation column for flotation. This pre-mixing process of coal water slurry and air is usually called pre-mineralization.

[0004] There are various devices for pre-mixing coal water slurry and air in the prior art. A common device is to use a Venturi-type gas-liquid mixer, as Figure 1 shown. It passes the coal water slurry through a Venturi tube, and at the same time sets the gas inlet at the throat of the Venturi tube. Since the diameter at the throat of the Venturi is much smaller than the diameters of its upstream and downstream inlets and outlets, the flow rate of the coal water slurry at the throat is very fast, in a jet state. According to Bernoulli's principle, the faster the fluid flow rate, the lower the static pressure. Thus, a negative pressure is generated at the throat (this negative pressure can even reach more than 700 mmHg), sucking in external air to complete the gas-liquid mixing process. Although this Venturi mixer has strong air extraction ability and intense gas-liquid mixing, it has the following disadvantages: the negative pressure at the throat is greatly affected by the downstream equipment or pipelines of the Venturi tube. Therefore, the negative pressure at the throat is unstable, resulting in unstable air intake and large fluctuations in the gas-liquid mixing ratio, which is not conducive to the stable operation of the subsequent foam flotation column. In addition, the existing multiphase flow mixers have poor mixing effects. Specifically, when applied to the mineralization of coal water slurry, the mineralization effect of the coal water slurry is poor. After the coal water slurry is mineralized by the traditional mixer, the combustible particles containing carbon and hydrogen on the surface of the coal water slurry can only adhere to larger bubbles, resulting in poor separation effect between the subsequent combustible particles containing carbon and hydrogen and mineral particles, and too low recovery rate of the combustible matter after separation.

[0005] To solve the above problems, the present invention is proposed. Summary of the Invention

[0006] In a first aspect of the present invention, a Venturi-type multiphase fluid mixer is provided, which comprises the following components:

[0007] A sleeve 1 with openings at both ends and having a cavity inside; the upstream end opening is the first material inlet 15, and the downstream end opening is the mixed material outlet 16; the first material enters the sleeve 1 through the first material inlet 15.

[0008] An upstream converging pipe 2, which is of a gradually decreasing diameter from the upstream end to the downstream end, with its upstream end being the first fluid inlet 21 and its downstream end being the first fluid outlet 22.

[0009] A downstream diverging pipe 3, which is of a gradually increasing diameter from the upstream end to the downstream end, with its upstream end being the second fluid inlet 31 and its downstream end being the second fluid outlet 32.

[0010] A multiphase fluid mixing chamber 4, which is located inside the cavity of the sleeve 1 and is defined between the upstream converging pipe 2 and the downstream diverging pipe 3.

[0011] A feed pipe 5, which introduces a second material into the multiphase fluid mixing chamber 4 through a second material inlet 11 located on the tube wall of the sleeve 1; the second material inlet 11 is located in the middle of the sleeve 1 and penetrates the tube wall of the sleeve 1.

[0012] The upstream converging pipe 2 and the downstream diverging pipe 3 are located inside the cavity of the sleeve 1; the zero gauge pressure, slightly positive pressure or slightly negative pressure means that the gauge pressure at the multiphase fluid mixing chamber 4 is -0.01 MPa to +0.01 MPa.

[0013] The cross-sectional area of the multiphase fluid mixing chamber 4 is larger than the cross-sectional area at the first fluid outlet 22.

[0014] The multiphase fluid mixing includes gas-liquid mixing, gas-liquid-solid mixing, liquid-liquid mixing, liquid-liquid-solid mixing; when it is gas-liquid mixing or gas-liquid-solid mixing, the first material inlet 15 admits a liquid flow phase or a liquid-solid flow phase (first material), and the feed pipe 5 admits a gas flow phase (second material); when it is liquid-liquid mixing or liquid-liquid-solid mixing, the first material inlet 15 admits a first liquid flow phase or a first liquid and solid mixed flow phase (first material), the feed pipe 5 admits a second liquid flow phase (second material), and the first liquid and the second liquid are immiscible.

[0015] Preferably, the upstream end of the downstream diffuser tube 3 has a boss 33 which extends into the multiphase fluid mixing chamber 4 for a certain distance, and an eddy current annulus 13 is formed between the boundary of the boss 33 and the inner wall of the sleeve 1. This boss design causes the gas-liquid mixed fluid to generate eddy currents at the edge of the boss (i.e., at the eddy current annulus 13), and these eddy currents will further increase the hydrostatic pressure of the fluid in the mixing chamber, making it close to micro-negative pressure or zero gauge pressure, and these eddy currents also strengthen the mixing effect of gas and liquid.

[0016] Preferably, the venturi-type multiphase fluid mixer further includes an additive inlet 14 penetrating through the tube wall of the sleeve 1 and an additive inlet pipe 6 communicating with the additive inlet 14. The medicament is added to the eddy current annulus 13 through the additive inlet pipe 6 via the additive inlet 14. When the multiphase fluid mixer is used for pre-mineralization of coal water slurry, the additive is mainly the medicament, including kerosene, diesel oil, and high-carbon mixed alcohols.

[0017] Preferably, the connection between the boss 33 and its main body, the downstream diffuser tube 3, has a fillet design, and the outer wall of the downstream end of the boss 33 is arc-shaped. During the mixing process of the multiphase materials in the multiphase fluid mixing chamber 4, there is a swirling flow at the eddy current annulus 13. The fillet design can improve the self-cleaning ability of the equipment and prevent the residual materials at the eddy current annulus 13.

[0018] Preferably, the distance between the upstream converging tube 2 and the downstream diffuser tube 3 is 1.5 - 3.5 times the diameter of the first fluid outlet 22, and the cross-sectional area of the multiphase fluid mixing chamber 4 is 60% - 100% of the cross-sectional area at the first fluid inlet 21.

[0019] Preferably, the inner side of the tube wall of the sleeve 1 also has a protruding buckle 12 to prevent the upstream converging tube 2 and the downstream diffuser tube 3 from moving towards the middle multiphase fluid mixing chamber 4.

[0020] Preferably, there is a positive pressure providing device upstream of the feed pipe 5. When the gauge pressure at the multiphase fluid mixing chamber 4 is zero gauge pressure or slightly positive pressure, the positive pressure providing device is used to introduce the second material into the multiphase fluid mixing chamber 4 through the feed pipe 5. When the second material is air, a blower can be selected.

[0021] Preferably, the upstream converging tube 2 and the downstream diffuser tube 3 are of a split type;

[0022] The sleeve 1, the upstream converging tube 2, the downstream diffuser tube 3, the feed pipe 5 or the additive inlet pipe 6 are detachably connected. This design is convenient for installation and disassembly. If an internal component is worn or damaged, it is convenient to disassemble and replace it.

[0023] Preferably, the sleeve 1 is selected from stainless steel materials.

[0024] Preferably, the upstream reducing pipe 2 and the downstream expanding pipe 3 are made of wear-resistant ceramic materials, selected from ZrO2 or SiC.

[0025] The second aspect of the present invention provides a gas-liquid mixing method for stably controlling the gas flow rate, which uses the Venturi-type multiphase fluid mixer described in the first aspect of the present invention. The method specifically includes the following steps:

[0026] (1) Feed the first material into the upstream reducing pipe 2 through the first material inlet 15 and the first fluid inlet 21. As the diameter of the upstream reducing pipe 2 gradually decreases, the velocity of the liquid material gradually increases, and the velocity of the liquid material reaches the maximum value at the first fluid outlet 22.

[0027] (2) The liquid material exits from the first fluid outlet 22 and enters the multiphase fluid mixing chamber 4. Since the cross-sectional area of the multiphase fluid mixing chamber 4 is larger than the cross-sectional area at the first fluid outlet 22, the flow velocity of the liquid material decreases, and thus the hydrostatic pressure at the multiphase fluid mixing chamber 4 increases to a slightly negative pressure, zero gauge pressure or even a slightly positive pressure. The gauge pressure of the multiphase fluid mixing chamber 4 is -0.01 MPa to +0.01 MPa.

[0028] (3) Use a positive pressure supply device to feed the second material into the multiphase fluid mixing chamber 4 through the feed pipe 5, or use a slightly negative pressure to suck the second material into the multiphase fluid mixing chamber 4 to complete the mixing process of the first material and the second material.

[0029] (4) The mixed material after mixing enters the downstream expanding pipe 3 through the second fluid inlet 31, and then is discharged from the multiphase fluid mixer through the second fluid outlet 32 and the mixed material outlet 16.

[0030] The gauge pressure at the multiphase fluid mixing chamber 4 is -0.01 MPa to +0.01 MPa, and the pressure range is controlled within a slightly negative pressure, slightly positive pressure or zero gauge pressure. The pressure at the multiphase fluid mixing chamber 4 here is affected by the feed flow rate. The multiphase flow mixer of the present invention can control the gauge pressure at the multiphase fluid mixing chamber 4 to be -0.01 MPa to +0.01 MPa within the range of a slightly negative pressure, slightly positive pressure or zero gauge pressure while ensuring the feed flow rate.

[0031] The multiphase fluid mixing includes gas-liquid mixing, gas-liquid-solid mixing, liquid-liquid mixing, liquid-liquid-solid mixing; when it is gas-liquid mixing or gas-liquid-solid mixing, the first material inlet 15 feeds a liquid phase or a liquid-solid phase, and the feed pipe 5 feeds a gas phase; when it is liquid-liquid mixing or liquid-liquid-solid mixing, the first material inlet 15 feeds a first liquid phase or a first liquid-solid mixed phase, and the feed pipe 5 feeds a second liquid phase, and the first liquid and the second liquid are immiscible.

[0032] In the third aspect of the present invention, a method for mixing multiphase fluid containing microparticles by using the Venturi-type multiphase fluid mixer is provided. The first material is a liquid-solid mixture containing microparticles; the second material is air; the volume ratio of the liquid-solid mixture containing microparticles to air in the Venturi-type multiphase fluid mixer is 1:0.2 - 1:1, and more preferably, it is 1:0.3 - 1:0.8;

[0033] Preferably, the liquid-solid mixture containing microparticles is coal water slurry, and the Venturi-type multiphase fluid mixer is used to mix the coal water slurry and air to pre-mineralize the coal water slurry; during the pre-mineralization process, a microparticle surface modification agent also needs to be added to the multiphase fluid mixing chamber 4;

[0034] The microparticle surface modification agent can be first mixed with the coal water slurry and then introduced into the Venturi-type multiphase fluid mixer as the first material; alternatively, an additive inlet can be further provided on the Venturi-type multiphase fluid mixer, and the microparticle surface modification agent is introduced into the Venturi-type multiphase fluid mixer through the additive inlet.

[0035] Pre-mineralization means that before the coal water slurry undergoes flotation separation, it is mixed with gas. Since coal is a complex mixture containing organic hydrocarbons and inorganic minerals. The organic components in coal are complex and are mixtures of hydrocarbon compounds with aromatic rings as the backbone. Its surface composed of non-polar bonds has strong hydrophobicity, so it is easy to combine with bubbles, and the process of its combination with bubbles is called the mineralization process; while the minerals in coal are mainly clay minerals and quartz, which have strong hydrophilicity, have a low adhesion probability to bubbles, and do not move upward with the bubbles. Therefore, by utilizing the difference in hydrophobicity between the two, they can be separated.

[0036] Preferably, the volume ratio of the coal water slurry to air in the Venturi-type multiphase fluid mixer is 1:0.2 - 1:1, and more preferably, it is 1:0.3 - 1:0.8.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The Venturi-type gas-liquid mixer of the present invention includes an upstream converging pipe 2, a downstream diverging pipe 3, and a multiphase fluid mixing chamber 4 therebetween. The present invention sets the cross-sectional area of the multiphase fluid mixing chamber 4 to be approximately equal to the cross-sectional area of the first fluid inlet 21 upstream thereof or the second fluid outlet 32 downstream thereof. Since the cross-sectional area at the multiphase fluid mixing chamber 4 is larger than the throat area (the first fluid outlet 22) or the cross-sectional area of the second fluid inlet (at 31), the flow rate of the liquid material at the multiphase fluid mixing chamber 4 decreases, and thus the hydrostatic pressure at the multiphase fluid mixing chamber 4 increases to a slightly negative pressure to a slightly positive pressure (gauge pressure -0.01 MPa to +0.01 MPa). An air supply device under positive pressure is used to introduce air into the multiphase fluid mixing chamber 4 through a feed pipe 5, or ambient air is inhaled into the multiphase fluid mixing chamber 4 using a slightly negative pressure to complete the gas-liquid mixing process. Since the hydrostatic pressure at the multiphase fluid mixing chamber 4 is a slightly negative pressure to a slightly positive pressure, the amount of the second material introduced is smaller and easier to control. Further, an air supply device under positive pressure is used to introduce air into the multiphase fluid mixing chamber 4. Since the positive pressure of the air supply device is very easy to stably control, the amount of air introduced into the multiphase fluid mixing chamber 4 can also be stably controlled. Further, since the hydrostatic pressure at the multiphase fluid mixing chamber 4 is a slightly negative pressure to a slightly positive pressure, the pressure at the throat is hardly affected by downstream equipment or pipelines, and the pressure is stable, which further improves the stable control of the air intake volume.

[0039] 2. The upstream end of the downstream diverging pipe 3 of the present invention has a boss 33, which extends into the multiphase fluid mixing chamber 4 for a certain distance. This boss design causes the gas-liquid mixed fluid to generate a vortex at the edge of the boss, and this vortex will further increase the hydrostatic pressure in the mixing chamber, making it close to a slightly negative pressure or zero gauge pressure, and this vortex also strengthens the gas-liquid mixing effect. Further, the connection between the boss 33 and its main body, the downstream diverging pipe 3, has a fillet design, and the outer wall of the downstream end of the boss 33 is arc-shaped. During the mixing process of the multiphase materials in the multiphase fluid mixing chamber 4, there is a swirling flow at the vortex annulus 13. The fillet design can improve the self-cleaning ability of the device and prevent the residual materials at the vortex annulus 13.

[0040] 3. The design of the present invention makes the flow rate of the water-coal slurry at the inlet of the multiphase fluid mixing chamber 4 (the first fluid outlet 22) approximately equal to the flow rate of the gas-liquid mixed fluid at the outlet of the multiphase fluid mixing chamber 4 (the second fluid inlet 31). Since the inlet and outlet flow rates are equal, there is no static pressure loss, and the pressure in the multiphase fluid mixing chamber 4 can also be close to a slightly negative pressure or zero gauge pressure, and the pressure is stable.

[0041] 4. The Venturi-type multiphase fluid mixer of the present invention not only retains the mixing effect of the traditional Venturi-type gas-liquid mixer but also avoids the problem that the air intake volume cannot be stably controlled.

[0042] 5. In a preferred embodiment, the upstream converging pipe 2 and the downstream diverging pipe 3 are made of wear-resistant ceramics, which improves the wear resistance compared to traditional steel Venturi tubes.

[0043] 6. In a preferred embodiment, the Venturi-type gas-liquid mixer is designed with an overall split structure, and the sleeve 1, the upstream converging pipe 2, the downstream diverging pipe 3 or the feed pipe 5 are detachably connected. This design facilitates installation and disassembly, and when an internal component is worn or damaged, it is convenient to disassemble and replace.

[0044] 7. The Venturi-type multiphase fluid mixer of the present invention can be used for pre-mineralization of water coal slurry, which not only ensures the enhanced gas-liquid mixing effect but also enables stable control of the air intake. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic structural diagram of a traditional Venturi-type gas-liquid mixer;

[0046] Figure 2 is a schematic structural diagram of the Venturi-type multiphase fluid mixer of the present invention;

[0047] Figure 3 is a schematic structural diagram of the upstream converging pipe 2 in the Venturi-type multiphase fluid mixer of the present invention;

[0048] Figure 4 is a schematic structural diagram of the downstream diverging pipe 3 in the Venturi-type multiphase fluid mixer of the present invention;

[0049] The description of the reference numerals is as follows:

[0050] 1 - Sleeve, 2 - Upstream converging pipe, 3 - Downstream diverging pipe, 4 - Multiphase fluid mixing chamber, 5 - Feed pipe, 6 - Additive addition pipe, 11 - Second material inlet, 12 - Snap fastener, 13 - Eddy current annulus, 14 - Additive addition port, 15 - First material inlet, 16 - Mixed material outlet, 21 - First fluid inlet, 22 - First fluid outlet, 31 - Second fluid inlet, 32 - Second fluid outlet, 33 - Boss. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The following further illustrates the content of the present invention through embodiments, but does not limit the present invention thereby.

[0052] Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific techniques or conditions, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For those materials or equipment without indicating the manufacturer, they are all conventional products that can be obtained by purchase.

[0053] Those skilled in the art of the present technology can understand that, unless specifically stated otherwise, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the description of the present invention means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" to another element, it can be directly connected to other elements, or there may also be intermediate elements. In addition, "connection" used herein may include wireless connection.

[0054] In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. The orientation or positional relationship indicated by terms such as "inside", "above", "below", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0055] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", and "provided with" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood as having a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as here.

[0057] Example 1

[0058] The Venturi-type multiphase flow mixer adopted in this example includes the following components:

[0059] A sleeve 1 with openings at both ends and a cavity inside; the upstream end opening is the first material inlet 15, and the downstream end opening is the mixed material outlet 16; the first material enters the sleeve 1 through the first material inlet 15.

[0060] The upstream converging pipe 2, which is of a gradually decreasing pipe diameter from the upstream end to the downstream end, has a first fluid inlet 21 at its upstream end with an inlet diameter of 20 mm and a first fluid outlet 22 at its downstream end with an outlet diameter of 6 mm;

[0061] The downstream diverging pipe 3, which is of a gradually increasing pipe diameter from the upstream end to the downstream end, has a second fluid inlet 31 at its upstream end and a second fluid outlet 32 at its downstream end;

[0062] The multiphase fluid mixing chamber 4 is located within the cavity of the sleeve 1 and is defined between the upstream converging pipe 2 and the downstream diverging pipe 3. The distance between the upstream converging pipe 2 and the downstream diverging pipe 3 is twice the diameter of the first fluid outlet 22;

[0063] The feed pipe 5 introduces a second material into the multiphase fluid mixing chamber 4 through a second material inlet 11 located on the pipe wall of the sleeve 1; the second material inlet 11 is located in the middle of the sleeve 1 and penetrates the pipe wall of the sleeve 1;

[0064] The upstream converging pipe 2 and the downstream diverging pipe 3 are located within the cavity of the sleeve 1; the inner diameter of the multiphase fluid mixing chamber 4 is three times the diameter at the first fluid outlet 22;

[0065] In this experiment, water was used as the first material and was fed into the first fluid inlet 21 through a booster water pump. Air entered the multiphase fluid mixing chamber 4 from the feed pipe 5; air was used as the second material. The end of the mixer was connected to a square water tank for observing and detecting the mixing effect of air and water. The main experimental parameters included a feed flow rate of 0.6, 0.9, 1.1, 1.3, 1.5 L / min, and the corresponding feed pressures were 0.1, 0.2, 0.3, 0.4, 0.5 MPa.

[0066] A comparative experiment was carried out using a traditional Venturi tube with a throat diameter of 6 mm, and the feed flow rate was kept the same. The results of the comparative experiment are shown in Table 1. The pressure at the air suction part of the traditional Venturi tube was between -0.062 and -0.388 MPa, and the pressure fluctuation amount under various conditions was between 0.01 and 0.04 MPa; the pressure at the air suction part of the mixer of the present invention was between 0.012 and -0.027 MPa, and the pressure fluctuation amount under various conditions was between 0.001 and 0.002 MPa. For the gas-liquid two-phase flow treated by the traditional Venturi tube, after entering the square tank, the bubble size was mainly between 3 - 30 mm, the bottom plate of the square tank was visible to the naked eye, and all the bubbles disappeared about 10 s after stopping the feed; for the gas-liquid two-phase flow treated by the mixer of the present invention, after entering the square tank, most of the bubbles could not be observed in size with the naked eye, that is, the bubble size was much smaller than that in the comparative experiment, and the gas-liquid mixture in the entire square tank was milky white, and all the bubbles disappeared about 60 s after stopping the feed.

[0067] Table 1 Comparison of pressures at the suction of the mixer at different feed flow rates

[0068]

[0069] Example 2

[0070] The Venturi-type multiphase flow mixer used in this example includes the following components:

[0071] The sleeve 1 has openings at both ends and has a cavity inside; the upstream end opening is the first material inlet 15, and the downstream end opening is the mixed material outlet 16; the first material enters the sleeve 1 through the first material inlet 15.

[0072] The upstream converging pipe 2 has a gradually decreasing pipe diameter from the upstream end to the downstream end. Its upstream end is the first fluid inlet 21, and its downstream end is the first fluid outlet 22, with an outlet diameter of 10 mm.

[0073] The downstream diverging pipe 3 has a gradually increasing pipe diameter from the upstream end to the downstream end. Its upstream end is the second fluid inlet 31, and its downstream end is the second fluid outlet 32.

[0074] The multiphase fluid mixing chamber 4 is located inside the cavity of the sleeve 1 and is defined between the upstream converging pipe 2 and the downstream diverging pipe 3. The distance between the upstream converging pipe 2 and the downstream diverging pipe 3 is 2.5 times the diameter of the first fluid outlet 22.

[0075] The feed pipe 5 introduces the second material into the multiphase fluid mixing chamber 4 through the second material inlet 11 located on the wall of the sleeve 1.

[0076] The upstream converging pipe 2 and the downstream diverging pipe 3 are located inside the cavity of the sleeve 1; the inner diameter of the multiphase fluid mixing chamber 4 is 3.5 times the diameter at the first fluid outlet 22.

[0077] The Venturi-type multiphase flow mixer further includes an additive addition port 14 penetrating the wall of the sleeve 1 and an additive addition pipe 6 communicating with the additive addition port 14. The medicament is added to the vortex oscillation chamber 13 through the additive addition pipe 6 via the additive addition port 14.

[0078] In this experiment, a coal slurry sample with a particle size of less than 100 mesh was taken and placed in a coal slurry storage tank. The stirring device of the storage tank was turned on to stir the coal slurry evenly to prevent sedimentation. The coal slurry mainly contains combustible particles containing carbon and hydrogen (separated and called clean coal), water, and mineral particles (or called ash, separated and called tail coal).

[0079] After the coal slurry is evenly mixed, use a diaphragm pump to transport the coal slurry to the coal slurry feed buffer tank. At the same time, start the coal slurry feed diaphragm pump, reagent pump, and air compressor, and transport the reagents in proportion. Add the collector and foaming agent to the additive addition pipe 6 after mixing. At the same time, start the air compressor and transport air in proportion. The ratio of coal slurry, mineralization reagent, and air is: 1:0.0015:0.4.

[0080] The downstream of the multiphase flow mixer with surface modification function is connected to the fine particle mineral separation device. After the mineralization-separation whole system is stable, it can be observed that the color of the clean coal foam overflow becomes significantly darker compared to the raw coal slurry, the color of the tail coal stream becomes grayish-white, and there are no obvious coal particles remaining. Mix, dehydrate, dry, and reduce the samples of the clean coal stream and the tail coal stream respectively, and use an industrial analyzer to test the ash content and calculate the combustible recovery rate. The results are shown in Table 2.

[0081] Among them, the calculation formula for the ash balance combustible recovery rate is as follows:

[0082]

[0083] In the formula, E a ——Ash balance combustible recovery rate (%);

[0084] A j --Dry basis ash content of clean coal (%);

[0085] A y --Dry basis ash content of raw coal (%);

[0086] A w --Dry basis ash content of tail coal (%).

[0087] Table 2 Continuous experimental results of the micro-nano separation tower using the multiphase flow mixer of the present invention

[0088]

[0089] For comparison, this test uses Figure 1 the traditional Venturi tube shown as the mixer to pre-mineralize the coal slurry under the same coal slurry raw material, the same feed flow rate, mineralization reagent, and air consumption (that is, the difference between the two groups of tests is only the mixer). After the same experimental process and sampling analysis process, the industrial analysis ash content test and combustible recovery rate results are shown in Table 3.

[0090] Table 3 Continuous experimental results of the micro-nano separation tower using the traditional Venturi tube as the mixer

[0091]

[0092] Through experimental comparison, it can be seen that after pre-mineralization using the mixer of the present invention, the ash content of clean coal is 15.39%, the ash content of tail coal is 80.96%, and the combustible recovery rate is 72.60%. For the coal slurry pre-mineralized by a traditional Venturi tube, the ash content of clean coal is 13.88%, the ash content of tail coal is 75.85%, and the combustible recovery rate is only 64.31%. Compared with the pre-mineralization using the mixer of the present invention, although the ash content of clean coal is slightly lower, the difference is small and within the error range. However, the ash content of tail coal is significantly reduced, which leads to a decrease in the combustible recovery rate. Therefore, compared with the traditional Venturi tube, the mixer of the present invention has a better multi-phase mixing and pre-mineralization effect on coal slurry, additives, and air, and can effectively improve the combustible recovery rate.

Claims

1. A Venturi-type multiphase fluid mixer, characterized in that, It includes the following components: A sleeve (1) with openings at both ends and a cavity inside; its upstream end opening is the first material inlet (15), and its downstream end opening is the mixed material outlet (16); the first material enters the sleeve (1) through the first material inlet (15). An upstream reducing pipe (2) with a gradually reducing diameter from the upstream end to the downstream end, its upstream end being the first fluid inlet (21) and its downstream end being the first fluid outlet (22). A downstream expanding pipe (3) with a gradually expanding diameter from the upstream end to the downstream end, its upstream end being the second fluid inlet (31) and its downstream end being the second fluid outlet (32). A multiphase fluid mixing chamber (4) located inside the cavity of the sleeve (1) and defined between the upstream reducing pipe (2) and the downstream expanding pipe (3). A feed pipe (5) that introduces a second material into the multiphase fluid mixing chamber (4) through a second material inlet (11) on the wall of the sleeve (1). An additive addition port (14) penetrating the wall of the sleeve (1). An additive addition pipe (6) communicating with the additive addition port (14). The upstream reducing pipe (2) and the downstream expanding pipe (3) are located inside the cavity of the sleeve (1), and the cross-sectional area of the multiphase fluid mixing chamber (4) is larger than the cross-sectional area at the first fluid outlet (22). The upstream end of the downstream expanding pipe (3) has a boss (33) that extends into the multiphase fluid mixing chamber (4) for a certain distance, and an eddy current annulus (13) is formed between the boundary of the boss (33) and the inner wall of the sleeve (1). The fine particle surface modification agent is added to the eddy current annulus (13) through the additive addition pipe (6) via the additive addition port (14). The connection between the boss (33) and its main body, the downstream expanding pipe (3), has a fillet design, and the outer wall of the downstream end of the boss (33) is arc-shaped.

2. The Venturi-type multiphase fluid mixer according to claim 1, characterized in that, The distance between the upstream reducing pipe (2) and the downstream expanding pipe (3) is 1.5 - 3.5 times the diameter of the first fluid outlet (22), and the cross-sectional area of the multiphase fluid mixing chamber (4) is 60% - 100% of the cross-sectional area at the first fluid inlet (21).

3. The Venturi-type multiphase fluid mixer according to claim 1, characterized in that, The inner side of the wall of the sleeve (1) also has a protruding buckle (12) to prevent the upstream reducing pipe (2) and the downstream expanding pipe (3) from moving into the middle multiphase fluid mixing chamber (4).

4. The Venturi-type multiphase fluid mixer according to claim 1, characterized in that, There is also a positive pressure providing device upstream of the feed pipe (5). When the gauge pressure at the multiphase fluid mixing chamber (4) is zero gauge pressure or slightly positive gauge pressure, the positive pressure providing device is used to introduce the second material into the multiphase fluid mixing chamber (4) through the feed pipe (5).

5. The Venturi-type multiphase fluid mixer according to claim 1, characterized in that, The upstream reducing pipe (2) and the downstream expanding pipe (3) are separate parts. The sleeve (1), the upstream reducing pipe (2), the downstream expanding pipe (3), the feed pipe (5), or the additive addition pipe (6) are detachably connected to each other.

6. A gas-liquid mixing method for stably controlling gas flow rate, characterized in that, Using the Venturi-type multiphase fluid mixer according to any one of claims 1 - 4 specifically includes the following steps: (1) Feed the first material into the upstream reducing pipe (2) through the first material inlet (15) and the first fluid inlet (21). As the diameter of the upstream reducing pipe (2) gradually decreases, the velocity of the liquid material gradually increases, and the velocity of the liquid material reaches the maximum value at the first fluid outlet (22). (2) The liquid material exits from the first fluid outlet (22) and enters the multiphase fluid mixing chamber (4). Since the cross-sectional area of the multiphase fluid mixing chamber (4) is larger than the cross-sectional area at the first fluid outlet (22), the flow velocity of the liquid material decreases, and thus the hydrostatic pressure at the multiphase fluid mixing chamber (4) increases to a slightly negative pressure, zero gauge pressure, or even a slightly positive pressure. (3) Use a positive pressure supply device to feed the second material into the multiphase fluid mixing chamber (4) through the feed pipe (5), or use a slightly negative pressure to suck the second material into the multiphase fluid mixing chamber (4) to complete the mixing process of the first material and the second material. (4) The mixed material after mixing enters the downstream expanding pipe (3) through the second fluid inlet (31), and then is discharged from the multiphase fluid mixer through the second fluid outlet (32) and the mixed material outlet (16). The gauge pressure at the multiphase fluid mixing chamber (4) is -0.01 MPa to +0.01 MPa, and the pressure range is controlled within a slightly negative pressure, slightly positive pressure, or zero gauge pressure. The multiphase fluid mixing includes gas-liquid mixing, gas-liquid-solid mixing, liquid-liquid mixing, and liquid-liquid-solid mixing. When it is gas-liquid mixing or gas-liquid-solid mixing, the first material inlet (15) feeds a liquid phase or a liquid-solid phase, and the feed pipe (5) feeds a gas phase. When it is liquid-liquid mixing or liquid-liquid-solid mixing, the first material inlet (15) feeds a first liquid phase or a first liquid-solid mixed phase, and the feed pipe (5) feeds a second liquid phase, and the first liquid and the second liquid are immiscible.

7. A method for mixing multiphase fluid containing microparticles using the Venturi-type multiphase fluid mixer according to any one of claims 1-6, characterized in that, The first material is a liquid-solid mixture containing fine particles. The second material is air. The volume ratio of the liquid-solid mixture containing fine particles to air in the Venturi-type multiphase fluid mixer is 1:0.2 - 1:

1. The liquid-solid mixture containing fine particles is a water-coal slurry, and the Venturi-type multiphase fluid mixer is used to mix the water-coal slurry and air for pre-mineralization of the water-coal slurry. During the pre-mineralization process, it is also necessary to add a fine particle surface modification agent to the multiphase fluid mixing chamber (4). The fine particle surface modification agent is first mixed with the water-coal slurry and then fed into the Venturi-type multiphase fluid mixer as the first material; or, an additive inlet is further provided on the Venturi-type multiphase fluid mixer, and the fine particle surface modification agent is fed into the Venturi-type multiphase fluid mixer through the additive inlet.

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