Method for promoting extrusion dehydration of coal gasification fine slag through mechanical hole breaking and vibration force field energizing

Abstract

The invention discloses a mechanical hole breaking and vibration force field energizing coal gasification fine slag extrusion dehydration promoting method which comprises the following steps that coal gasification fine slag is ground through a wet ball mill, ore grinding is conducted for 1-9 min to obtain slurry, and the carbon content particle median size d50 of the coal gasification fine slag obtained after ore grinding is 5.9-19.3 micrometers; carrying out vacuum filtration pretreatment on the slurry to obtain a vacuum filter cake with the water content of 47-53%; and carrying out vibration extrusion dehydration on the gasified fine slag after ore grinding by adopting a vibration extrusion dehydration device to obtain a filter cake with the water content of 29-36%. The method can improve the dehydration efficiency and reduce the dehydration energy consumption, and has a good dehydration effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of the treatment of coal-based solid waste, and particularly relates to a method for promoting the extrusion dehydration of fine slag for coal gasification by mechanical pore formation and vibration force field energy. Background Art

[0002] Coal gasification refers to the process of taking coal or coal char as raw materials, using steam, oxygen (or air), hydrogen, etc. as gasifying agents, and gasifying the combustible part of coal or coal char into combustible gas through chemical reactions at high temperatures. The composition of the obtained combustible gas is similar to that of blast furnace gas. The coal gasification slag produced during the coal gasification process is a typical solid waste generated in the coal chemical process, mainly divided into two types: coarse slag and fine slag. The coarse slag is in a molten state at high temperatures and is discharged from the furnace bottom. In the gasifier, the gas flow rate is too fast, and the reaction time between pulverized coal and the gasifying agent is limited. The gasification fine slag formed by the mixture of unreacted carbon and molten ash particles generated by complete reaction is carried out by the gas.

[0003] The gasification fine slag is produced in a high-temperature and high-pressure gasifier. It contains 20-40% by mass of unreacted carbon. The pores of this part of the residual carbon are very developed, and the specific surface area can reach 145 m 2 / g. The rich pores are natural "storages" for water, resulting in difficult removal of water from the pores and the skeleton during the dehydration process, leading to poor dehydration effect. During the extrusion dehydration process, as the pressure increases, the dehydration capacity first increases and then slows down. When the dehydration capacity reaches a bottleneck, further increasing the pressure to a certain value, the high extrusion pressure can destroy the particle structure and further promote the dehydration process. This means that the destruction of the particle structure can make the arrangement of particles closer, the "storage" for water hiding is destroyed, and the water is forced to transfer to achieve further efficient dehydration.

[0004] Currently, before the gasification slag enters dehydration, flocculants such as polyacrylamide are generally used to flocculate the coal gasification fine slag. After concentration in the thickener, the slurry concentration increases from 2-3% to 8-20%, and then enters the dehydration equipment (such as a vacuum horizontal filter cloth machine, a filter press, a horizontal screw centrifuge) for dehydration treatment. These dehydration equipment generate dehydration force fields such as vacuum negative pressure, extrusion, and centrifugal force, and mostly use a single dehydration force field. Therefore, there are disadvantages such as poor dehydration effect, low efficiency, and high energy consumption. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for promoting the extrusion dehydration of fine slag for coal gasification by mechanical pore formation and vibration force field energy, which can improve the dehydration efficiency, reduce the dehydration energy consumption, and has a good dehydration effect.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a method for promoting the extrusion dehydration of fine slag for coal gasification by mechanical pore formation and vibration force field energy, including the following steps:

[0007] (1) Grind the fine slag of coal gasification with a wet ball mill. After grinding for 1 - 9 minutes, a slurry is obtained. After grinding, the median particle size d of the carbon content in the fine slag of coal gasification 50 is 5.9 - 19.3 μm;

[0008] (2) Pretreat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a moisture content of 47 - 53%;

[0009] (3) Use a vibration extrusion dehydration device to perform vibration extrusion dehydration on the vacuum filter cake obtained in step (2) to obtain a filter cake with a moisture content of 29 - 36%.

[0010] Preferably, in step (1), after grinding for 1 minute, the median particle size d of the carbon content in the fine slag of coal gasification 50 is 19.3 μm.

[0011] Preferably, in step (1), after grinding for 3 minutes, the median particle size d of the carbon content in the fine slag of coal gasification 50 is 9.5 μm.

[0012] Preferably, in step (1), after grinding for 6 minutes, the median particle size d of the carbon content in the fine slag of coal gasification 50 is 6.8 μm.

[0013] Preferably, in step (1), after grinding for 9 minutes, the median particle size d of the carbon content in the fine slag of coal gasification 50 is 5.9 μm.

[0014] Preferably, in step (1), the rotational speed of the ball mill is 100 r / min, the ball milling medium accounts for 10 wt% of the mass of the fine slag of coal gasification, and the percentage of the mass of the solid material contained in the slurry is 30%.

[0015] Preferably, in step (1), the specific surface area of the fine slag of coal gasification is 145 m 2 / g, the loss on ignition LOI is 24%, and the median particle size d of the carbon content 50 is 47 μm.

[0016] Preferably, in step (3), the extrusion strength is 7 - 10 MPa, the vibration force is 2.3 MPa and the vibration frequency is 23 - 45 Hz, and the extrusion dehydration time is 1 - 5 minutes.

[0017] Preferably, in step (3), the inner diameter of the dehydration mold is 150 mm, and each time 2 kg of the vacuum filter cake obtained in step (2) is fed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses a wet grinding method to grind the particles in the gasification fine slag black water. This grinding process destroys the irregularly shaped porous residual carbon structure. In this process, both pore breaking and preventing the particles from being too fine need to be achieved. If the grinding is too fine, more fine particles will be generated, the specific surface area will increase, the water holding capacity will increase, and at the same time, the path length of the water removal process will increase, which is not conducive to dehydration. The present invention grinds the median size d of the carbon-containing particles in the coal gasification fine slag 50 to be maintained between 5.9 and 19.3 μm to obtain the optimal mechanical pore breaking conditions; subsequently, the material is placed in a vibration extrusion composite dehydration system. In this process, the vibration force field can accelerate the particle slip under the extrusion condition. Under the action of extrusion and vibration, the gasification fine slag particles can be closely arranged, compressing the skeleton / pore space where water exists, so as to achieve the purpose of high dehydration efficiency, good dehydration effect and low dehydration energy consumption. Specific embodiments

[0020] The present invention will be further described in detail below with reference to specific embodiments.

[0021] All raw material reagents in the embodiments of this application are purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0022] The specific surface area of the coal gasification fine slag used in the following examples is 145 m 2 / g, the loss on ignition LOI is 24%, and the median size d of the carbon-containing particles 50 is 47 μm.

[0023] In step (1) of the following examples, the rotational speed of the ball mill is 100 r / min, the ball milling medium accounts for 10 wt% of the mass of the coal gasification fine slag, and the percentage of the solid material mass contained in the slurry is 30%.

[0024] In step (3) of the following examples, the inner diameter of the dehydration mold is 150 mm, and each time 2 kg of the vacuum filter cake amount in step (2) is fed.

[0025] Comparative example 1

[0026] A dehydration method for coal gasification fine slag, directly extruding and dehydrating the coal gasification fine slag with an extrusion dehydration device under the conditions of an extrusion intensity of 10 MPa and an extrusion dehydration time of 1 min to obtain a filter cake with a moisture content of 39%.

[0027] Comparative example 2

[0028] A dehydration method for coal gasification fine slag, vibrating and extruding and dehydrating the coal gasification fine slag with a vibrating extrusion dehydration device under the conditions of an extrusion intensity of 10 MPa, a vibration force of 2.3 MPa, a vibration frequency of 23 Hz, and an extrusion dehydration time of 1 min to obtain a filter cake with a moisture content of 38%.

[0029] Example 1

[0030] A method for promoting the extrusion dehydration of fine slag from coal gasification by mechanical pore formation and vibration force field energy supply, comprising the following steps:

[0031] (1) Grind the fine slag from coal gasification using a wet ball mill. After grinding for 1 minute, a slurry is obtained. The median size d of the carbon-containing particles of the fine slag from coal gasification after grinding 50 is 19.3 μm;

[0032] (2) Pre-treat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a water content of 47%;

[0033] (3) Use a vibration extrusion dehydration device to perform vibration extrusion dehydration on the vacuum filter cake obtained in step (2) under the conditions of an extrusion intensity of 7 MPa, a vibration force of 2.3 MPa, a vibration frequency of 23 Hz, and an extrusion dehydration time of 1 minute to obtain a filter cake with a water content of 36%.

[0034] Example 2

[0035] A method for promoting the extrusion dehydration of fine slag from coal gasification by mechanical pore formation and vibration force field energy supply, comprising the following steps:

[0036] (1) Grind the fine slag from coal gasification using a wet ball mill. After grinding for 1 minute, a slurry is obtained. The median size d of the carbon-containing particles of the fine slag from coal gasification after grinding 50 is 19.3 μm;

[0037] (2) Pre-treat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a water content of 47%;

[0038] (3) Use a vibration extrusion dehydration device to perform vibration extrusion dehydration on the vacuum filter cake obtained in step (2) under the conditions of an extrusion intensity of 10 MPa, a vibration force of 2.3 MPa, a vibration frequency of 23 Hz, and an extrusion dehydration time of 3 minutes to obtain a filter cake with a water content of 33%.

[0039] Example 3

[0040] A method for promoting the extrusion dehydration of fine slag from coal gasification by mechanical pore formation and vibration force field energy supply, comprising the following steps:

[0041] (1) Grind the fine slag from coal gasification using a wet ball mill. After grinding for 3 minutes, a slurry is obtained. The median size d of the carbon-containing particles of the fine slag from coal gasification after grinding 50 is 9.5 μm;

[0042] (2) Pre-treat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a water content of 47%;

[0043] (3) Use a vibration extrusion dewatering device to perform vibration extrusion dewatering on the vacuum filter cake obtained in step (2) under the conditions of an extrusion strength of 10 MPa, a vibration force of 2.3 MPa, a vibration frequency of 45 Hz, and an extrusion dewatering time of 3 min to obtain a filter cake with a moisture content of 31%.

[0044] Example 4

[0045] A method for promoting the extrusion dewatering of fine slag from coal gasification by mechanical pore formation and vibration force field energy supply, comprising the following steps:

[0046] (1) Grind the fine slag from coal gasification using a wet ball mill to obtain a slurry after grinding for 6 min. The median size d of the carbon-containing particles of the fine slag after grinding 50 is 6.8 μm;

[0047] (2) Pre-treat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a moisture content of 47%;

[0048] (3) Use a vibration extrusion dewatering device to perform vibration extrusion dewatering on the vacuum filter cake obtained in step (2) under the conditions of an extrusion strength of 10 MPa, a vibration force of 2.3 MPa, a vibration frequency of 45 Hz, and an extrusion dewatering time of 3 min to obtain a filter cake with a moisture content of 29%.

[0049] Example 5

[0050] A method for promoting the extrusion dewatering of fine slag from coal gasification by mechanical pore formation and vibration force field energy supply, comprising the following steps:

[0051] (1) Grind the fine slag from coal gasification using a wet ball mill to obtain a slurry after grinding for 9 min. The median size d of the carbon-containing particles of the fine slag after grinding 50 is 5.9 μm;

[0052] (2) Pre-treat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a moisture content of 47%;

[0053] (3) Use a vibration extrusion dewatering device to perform vibration extrusion dewatering on the vacuum filter cake obtained in step (2) under the conditions of an extrusion strength of 10 MPa, a vibration force of 2.3 MPa, a vibration frequency of 45 Hz, and an extrusion dewatering time of 5 min to obtain a filter cake with a moisture content of 30%.

[0054] According to the results of the above embodiments, it is found that introducing a vibration force field during the extrusion dehydration process can improve the dehydration effect of gasification slag; under the same dehydration conditions, it helps to improve the dehydration effect of fine gasification slag in the initial stage of grinding pretreatment of gasification slag. This is because the grinding process can effectively destroy the irregular shape and large pore structure on the surface of the residual carbon in the fine gasification slag, reducing the skeleton space constructed between particles during the extrusion dehydration process and facilitating dehydration. Comparing Example 4 and Example 5, it can be seen that excessive grinding leads to serious particle pulverization, significantly increasing the specific surface area of the particles. At the same time, the moisture migration path during the dehydration process increases, restricting the effective removal of moisture. Therefore, the carbon content and particle median size d of the fine slag after coal gasification in the grinding process need to be strictly controlled 50 , that is, grinding pretreatment is required to improve the dehydration process, while preventing excessive grinding from restricting the dehydration effect instead; in addition, both the grinding pretreatment of gasification slag and the introduction of a vibration force field can effectively improve the dehydration effect, and the two produce a synergistic promotion effect. This is because the irregular shape and rich pore channels on the surface of the gasification slag particles after grinding pretreatment are destroyed. During the extrusion dehydration process, the introduction of the vibration force field can accelerate the sliding of the gasification slag particles after grinding, making the arrangement of particles more compact, compressing the moisture storage space, and thus improving the dehydration effect.

[0055] In summary, the grinding pretreatment in the present invention helps to improve the dehydration effect of gasification slag, but excessive grinding should be prevented to avoid being unfavorable to dehydration; in addition, introducing a vibration force field during the extrusion dehydration process can improve the dehydration effect, and the introduction of the vibration force field in combination with the grinding pretreatment will produce a more significant synergistic promotion effect on dehydration.

Claims

1. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, It includes the following steps: (1) Grind the fine slag of coal gasification with a wet ball mill. After grinding for 1 - 9 minutes, a slurry is obtained. The median particle size d of the carbon content in the fine slag of coal gasification after grinding 50 is 5.9 - 19.3 μm; (2) Pretreat the slurry obtained in step (1) by vacuum filtration to obtain a vacuum filter cake with a moisture content of 47 - 53%. (3) Use a vibration extrusion dehydration device to perform vibration extrusion dehydration on the vacuum filter cake obtained in step (2) to obtain a filter cake with a moisture content of 29 - 36%.

2. A method for promoting mechanical hole punching and vibration force field energy - enabling extrusion dehydration of fine slag in coal gasification, according to claim 1, characterized in that In step (1), after grinding for 1 min, the median size d of the carbon content particles of the fine slag from coal gasification 50 is 19.3 μm.

3. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, In step (1), after grinding for 3 minutes, the median particle size d of the carbon content of the fine slag from coal gasification 50 is 9.5 μm.

4. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, In step (1), after grinding for 6 minutes, the median particle size d of the carbon content of the fine slag from coal gasification 50 is 6.8 μm.

5. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, In step (1), after grinding for 9 minutes, the median particle size d of the carbon content particles in the fine slag of coal gasification 50 is 5.9 μm.

6. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energization, characterized in that, In step (1), the rotational speed of the ball mill is 100 r / min, the ball milling medium accounts for 10 wt% of the mass of the fine slag from coal gasification, and the percentage of the mass of the solid material contained in the slurry is 30%.

7. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, In step (1), the specific surface area of the fine slag from coal gasification is 145 m 2 / g, the loss on ignition (LOI) is 24%, and the median size d 50 of the carbon-containing particles is 47 μm.

8. A method for promoting the extrusion dehydration of fine slag in coal gasification by mechanical hole breaking and vibration force field energy supply, characterized in that, In step (3), the extrusion strength is 7 - 10 MPa, the vibration force is 2.3 MPa, the vibration frequency is 23 - 45 Hz, and the extrusion dehydration time is 1 - 5 min.

9. A method for promoting mechanical hole breaking and vibration force field energization of coal gasification fine slag extrusion dehydration, according to claim 1 or 2, characterized in that In step (3), the inner diameter of the dehydration die is 150 mm, and each time 2 kg of the vacuum filter cake obtained in step (2) is fed.