WO2019001231A1

WO2019001231A1 - Process for producing high calorific value water-coal slurry by utilizing coal or coal gangue, and coal gasification process using same

Info

Publication number: WO2019001231A1
Application number: PCT/CN2018/089958
Authority: WO
Inventors: 刘科; 翁力; 吴昌宁
Original assignee: 深圳瑞科天启科技有限公司
Priority date: 2017-06-27
Filing date: 2018-06-05
Publication date: 2019-01-03
Also published as: CN107267236A

Abstract

A process for producing high calorific value water-coal slurry by utilizing coal or coal gangue. The coal or the coal gangue comprises incombustible minerals and combustible containing carbon-hydrogen. The process comprises the following steps: A. wet-grinding coal or coal gangue in water until an average particle size of particles is smaller than 500 micrometers, adding additives in a continuous wet-grinding process, and uniformly dispersing the additives, to obtain micro-nano water-coal slurry; B. introducing micro-bubbles with a diameter smaller than 200 micrometers into the micro-nano water-coal slurry, wherein the mineral particles bonded with the additives are agglomerated and sunken as a bottom stream, and the combustible particles containing the carbon-hydrogen floats along with the bubbles to be a floating stream, so that the separation of the mineral particles and the combustible particles can be realized; and C. separating the combustible particles containing the carbon-hydrogen from the floating stream, and preparing the high calorific value water-coal slurry with a calorific value higher than 4000 kcal/kg by virtue of press filtering. Also provided are the high calorific value water-coal slurry, use of using the high calorific value water-coal slurry as a raw material of a coal gasification process, and the coal gasification process.

Description

Process for producing high calorific value coal water slurry by using coal or coal gangue and coal gasification process using the same

Technical field

The invention belongs to the field of coal gasification process, and particularly relates to a method for producing high calorific value coal water slurry by using coal or coal gangue and by-product mineral compound fertilizer.

Background technique

In the traditional coal gasification process, according to the different raw materials used in the gasification furnace, it is divided into a dry coal gasification process and a coal water slurry coal gasification process. The former directly carries the compressed coal gas into the gasifier for gasification. The latter usually mixes pulverized coal with water into a coal water slurry and then enters the gasifier for gasification. Because the wet coal gasification process is superior to the dry coal gasification process in terms of feed continuity, stability and cost, the former has more application prospects in industry. In fact, coal slurry gasification has been widely used. Almost all chemical fertilizers in China produce hydrogen through coal gasification, and further synthesize ammonia to produce various fertilizers.

Current commercial wet coal gasifiers have stringent requirements on raw coal water slurry, such as requiring high solids content to ensure high calorific value and high gasification efficiency while ensuring flow stability of the coal water slurry; The ash in the coal water slurry is as low as possible in order to reduce the erosion of the ash slag entrained in the high temperature airflow in the gasifier to the refractory bricks constituting the gasifier wall, because of the oxides of metals such as iron, calcium and magnesium in the ash. It will penetrate into the interior of the refractory brick and cause a chemical reaction, resulting in loose interior of the refractory brick, reduced strength, and corrosion of the refractory brick.

The above strict requirements for coal water slurry lead to the current coal gasification industry can only use high quality coal as raw material for preparing coal water slurry, wherein the high quality coal index is as follows: the heating value is higher than 4500 kcal / kg, and the ash content is lower than 20wt%. The coal-water slurry gasifier cannot process and treat inferior coal, which greatly limits the application range of the coal-water slurry gasification process. At the same time, the production of high-quality coal is decreasing and the cost is high, while a large amount of inferior coal in coal mines cannot be effectively utilized in addition to being used as household fuel. Inferior coal generally has at least one of the following characteristics: high ash content, low fixed carbon content, high volatility content of ashless dry base, low ash softening temperature, large smoke generation during combustion, easy coking, high coal gangue content, Low heat (heat is usually less than 4500 kcal / kg), and so on. For the sake of uniformity, inferior coal is defined in the present invention as coal comprising carbon-hydrogen containing combustibles and at least 20 wt% of mineral impurities. For example, inferior coal may be washed coal, coal slime or coal gangue. There is an urgent need in the art for a technology capable of preparing qualified coal water slurry using inferior coal as a raw material, but low quality coal is characterized by high mineral impurity content (generally higher than 20 wt%, for example, 25 to 45 wt%), and low calorific value. It cannot be used to prepare qualified coal water slurry to supply the existing gasifier after direct pulverization. The inferior coal must be subjected to the necessary purification treatment to fully separate the carbon-hydrogen-containing combustibles from the minerals, so that it is possible to prepare high-quality coal-water slurry from the inferior coal.

The mineral impurities present in the raw coal are roughly divided into two types, the first of which is the soil or rock fragments mixed with the surrounding ground environment during the coal formation process, and the carbon-hydrogen-containing combustibles in the raw coal. Mixed at a macro scale, and the degree of bonding is relatively weak. The other is the mineral micronutrients that the original wood absorbs from the roots of the plant itself during its growth. Because it is symbiotic with wood, this part of mineral impurities and carbon-hydrogen-containing combustibles are microscopic. The scales are mixed and the binding is very tight. The conventional coal washing process and coal preparation process can only separate the first mineral impurities in the raw coal, but they cannot combine the carbon-hydrogen-containing combustibles and the second mineral impurities in the raw coal at the microscopic scale. A very effective separation is carried out, especially for poor quality coal. In addition, in the prior art coal water slurry, only the raw coal is usually pulverized to about 60-100 micrometers, because the cost is increased sharply, and the overall efficiency of the process cannot be increased, which is not worth the loss.

The existing coal gasifiers also produce a large amount of mineral residues by-product, and how to deal with these mineral residues is also a serious problem for coal gasification enterprises. Usually these mineral residues are only suitable for use as the lowest raw material for brick making or cementing or paving, but if there are no brick or cement plants near the coal gasification plant, the high transportation costs make it impossible to be used. . It has also been proposed to use these mineral residues as soil fertilizers or soil amendments, but the problem is that these mineral residues have been fully sintered or even vitrified after passing through the high temperature environment in the gasifier, and the useful minerals are trace amounts. The element is difficult to release under natural conditions, so it is difficult to be absorbed by the plant roots, and its effect as a fertilizer or soil amendment is very limited. Based on various factors, the large amount of these mineral residues in the coal gasification plant can only be disposed of and discarded, which has no other use, which causes environmental pollution and cannot recover economic value from it.

The present invention is directed to solving all of the above problems.

Summary of the invention

A first aspect of the present invention provides a process for producing a high calorific value coal water slurry using coal or coal gangue, wherein the coal or coal gangue comprises a non-combustible mineral and a carbon-hydrogen containing combustible, the process comprising the following step:

A. The coal or coal gangue is wet-milled in water until the average particle size of the particles is less than 500 micrometers, and then the additive is added to the coal water slurry to be uniformly mixed and dispersed uniformly during the wet grinding process to obtain the micro-nano coal water slurry containing the additive. ;

B. introducing microbubbles having a diameter of less than 200 micrometers into the micro-nano coal slurry containing the additive, wherein the mineral particles adhering to the additive are agglomerated and sink as an underflow, wherein the carbon-hydrogen-containing combustibles The particles float up with the bubbles to become a floating stream, thereby separating the carbon-hydrogen-containing combustible particles from the mineral particles;

C. The carbon-hydrogen-containing combustible particles are separated from the floating stream, and are mixed by pressure filtration to prepare a high calorific value coal water slurry having a calorific value higher than 4000 kcal/kg.

Wherein the additive is a hydrophilic nanoparticle, a collector or a surfactant, wherein the hydrophilic nanoparticle is an aluminosilicate nanoparticle, preferably further by separating the mineral particles separated in step B. Grinding to a nanometer scale range; wherein the collector is an organothio compound. Preferably, an alkali metal alkyl dithiocarbonate such as sodium alkyl dithiocarbonate or alkyl dithiocarbonate Potassium; wherein the surfactant is a surface active molecule having a hydrophilic group and a hydrophobic group, preferably pine oil, camphor oil, phenolic acid mixed fatty alcohol, isomeric hexanol, octanol, ether alcohol, ester Class of substances. The surfactant acts to adsorb to the water-air interface to reduce the surface tension of the aqueous solution, so that the air filled in the water is easily dispersed into bubbles and stabilize the bubbles.

The additive further includes: a pH adjuster and a flocculant. Wherein the pH adjusting agent such as lime, sodium carbonate, sodium hydroxide and sulfuric acid serves to adjust the pH of the micro-nano coal slurry to control the surface characteristics of the mineral, the chemical composition of the slurry and the action conditions of various other agents, thereby Improving the flotation effect; wherein the flocculating agent such as polyacrylamide and starch acts to aggregate mineral fine particles into large particles to accelerate the sedimentation speed in water; flocculation-de-sludge and flocculation by selective flocculation Flotation.

Wherein the coal or coal gangue is comminuted in step A to an average particle size of less than 500 microns, preferably less than 400 microns, preferably less than 300 microns, preferably less than 200 microns, preferably less than 100 microns, preferably less than 50 microns, preferably less than Particles of 20 microns, preferably less than 10 microns, preferably less than 5 microns.

The microbubbles are produced in step B by a microbubble generator having a diameter of from several micrometers to 200 micrometers, preferably from several micrometers to several tens of micrometers, more preferably the diameter of the microbubbles is average particles of coal or coal gangue particles. 50% to 200% of the diameter.

The inventors have also found that whether high-quality coal or inferior coal or coal gangue, the particle size of the crushed particles below 500 micrometers can make the carbon-hydrogen-containing combustible particles and non-combustible mineral particles The subsequent microbubble flotation process is significantly separated, the finer the particle size, and the more similar the microbubble diameter is to the particle diameter (for example, the diameter of the microbubbles is in the range of 50% to 200% of the average particle size of the coal or coal gangue particles). Inside), the separation effect of the two microbubble flotation processes is better. Therefore, for inferior coal or coal gangue, it is generally preferred to pulverize to below 500 microns, preferably below 400 microns, preferably below 300 microns, preferably below 200 microns, more preferably below 100 microns, such as around 80 microns, preferably around 30 microns. More preferably, it is about 10 micrometers, and most preferably 5 micrometers or less, so that the carbon-hydrogen-containing combustible particles and the incombustible mineral particles can be sufficiently separated in the subsequent bubble flotation process. The invention is particularly suitable for preparing high calorific value coal water slurry and by-product mineral compound fertilizer by using inferior coal or coal gangue as raw materials.

The coal is selected from high quality coal having a calorific value of more than 4500 kcal/kg or inferior coal having a calorific value of less than 4500 kcal/kg, wherein the inferior coal comprises washed coal or slime or coal gangue.

The second aspect of the invention relates to a high calorific value coal water slurry having a calorific value higher than 4000 kcal/kg, and a combustible solid content of more than 55 wt%, preferably more than 60 wt%, based on the dry basis percentage; 10重量%, preferably less than 5wt%; wherein the hydrocarbon combustible material particles have a particle size of less than 500 microns, preferably less than 400 microns, preferably less than 300 microns, preferably less than 200 microns, preferably less than 100 microns, preferably less than 50 Particles of micron, preferably less than 20 microns, preferably less than 10 microns, preferably less than 5 microns. The high calorific value coal water slurry is prepared by the process of the first aspect of the invention.

A third aspect of the invention relates to the use of the aforementioned high calorific value coal water slurry as a raw material for a coal gasification process, which is used for one or a combination of the following uses: using inferior coal or coal gangue as a raw material, reducing oxygen consumption, reducing energy consumption or increasing Gasification efficiency; or the use of the aforementioned high calorific value coal water slurry as a coal water slurry boiler fuel for reducing nitrogen oxides, sulfur oxides and/or particulate matter emissions from boilers.

A fourth aspect of the invention relates to a coal gasification process comprising the steps of:

A. using the process of the first aspect of the invention to produce high calorific value coal water slurry using coal or coal gangue;

B. The high calorific value coal water slurry is sent to a gasification furnace for gasification.

Preferably, the above coal gasification process can use inferior coal or coal gangue as a raw material for preparing the coal water slurry.

The beneficial effects of the invention:

1. So far, the inability of inferior coal for gasification of coal water slurry has been plaguing the field of coal gasification. The stable and reliable operation of coal-water slurry gasification is the first choice for gasification technology; however, in many places in China, there is no need for high-quality coal to meet the coal quality requirements of coal-water slurry gasification, which makes some coal gasification-based industries such as fertilizer industry, methanol and Other chemical manufacturing, and coal-to-liquid, coal-to-gas and other industries cannot adopt mature and stable coal-water slurry gasification technology. The invention solves the pain point in the field of coal gasification, in particular, the inferior coal or coal gangue can be used not only for the gasification of coal water slurry, but also for the production of trace element mineral compound fertilizer; therefore, the invention can make coal gasification chemical fertilizer The profit margin of the process has doubled.

2. The present invention first contemplates pulverizing coal or coal gangue to particles having a particle size of less than 500 microns, and surprisingly discovering that when coal or coal gangue, especially inferior coal, is comminuted to this particle size range, and supplemented by the present invention In the step B, the hydrocarbon combustible material particles and the mineral impurity particles can be almost completely separated from each other at the particle level, and based on the unexpected discovery, the micro-nano bubble flotation technology can be used to efficiently infer the quality. The hydrocarbon combustible material particles in the coal are separated from the mineral impurity particles. This greatly breaks through the conventional thinking of those skilled in the art. Especially for inferior coal or coal gangue, limited by the technical bias in the field, the technicians have no motivation to use it as raw material to prepare high calorific value coal water slurry, and there is no motive to envisage using it to prepare mineral compound fertilizer. The invention can be applied to inferior coal or coal gangue, which is a major breakthrough with respect to the prior art, because all coal gasification furnaces so far cannot use low quality coal as raw material for preparing coal water slurry, but must use high quality coal. The appearance of the invention greatly expands the range of raw materials used in the existing coal gasifier, and does not require any modification of the existing coal gasifier itself, and it is only necessary to add the high calorific value water described in the present invention before the coal gasifier. The process equipment of coal slurry can be.

3. Since the invention realizes efficient separation of carbon fuel particles and mineral impurity particles in inferior coal, the solid content is more than 55 wt% for the first time based on the isolated low ash low particle size high purity carbonaceous fuel particles. Even higher than 60wt% high-concentration coal water slurry, its calorific value is higher than 4000 kcal / kg coal water slurry, its ash content can be as low as 10wt% or less, even as low as 2wt% or less, breaking the above high calorific value coal The technology has historically been biased only by high quality coal. Of course, if high quality coal is used as the raw material of the technical solution of the present invention, the calorific value of the prepared coal water slurry will be higher. In addition, based on the actual production data, oxygen consumption, energy consumption (in terms of coal consumption) analysis, the solid content in the coal water slurry is increased by 2%, the oxygen consumption can be reduced by about 20 cubic meters per 1000 cubic meters, and the coal consumption is reduced by 1000 cubic meters. About 16 kilograms; under the same reaction conditions, for every 1% reduction in ash content in coal water slurry, oxygen consumption is reduced by about 0.7-0.8%, and coal consumption is reduced by about 1.3-1.5%. Therefore, the present invention realizes a solid content of 55 wt% or more and an ash content of 10 wt% or less in the coal water slurry, which is of great significance for reducing oxygen consumption and coal consumption.

4. The present invention utilizes microbubbles having a diameter of less than 200 micrometers, preferably several micrometers to several tens of micrometers, for the first time for froth flotation, and more preferably microbubbles having a diameter comparable to that of coal particles for froth flotation. In the previous coal preparation process, the diameter of the bubbles used was mostly from several hundred micrometers to several thousand micrometers. It has never been expected that the use of such small microbubbles can effectively carry out hydrocarbon combustible material particles and mineral impurity particles. Sufficient separation, especially unpredictable, is such that the hydrocarbon combustible material particles in the inferior coal or coal gangue are sufficiently separated from the mineral impurity particles.

5. The mineral impurity particles in the present invention are separated from the hydrocarbon combustible material before entering the gasification furnace, and are not subjected to high-temperature sintering treatment in the gasification furnace, so that the minerals contained therein are easily Released under natural conditions and absorbed by plant roots. It is not difficult to find out the source of these mineral impurities. The second mineral impurity mentioned above is precisely the mineral nutrients absorbed by ancient trees from ancient soils and exists in ancient woods and undergoes complex geological coal formation. It becomes a current mineral impurity. Therefore, these mineral impurities are essentially mineral fertilizers that have been effectively absorbed and preserved by ancient trees. Such precious ancient fertilizers are sintered at high temperatures in current coal gasifiers and become incapable of being absorbed by today's plants, which is tantamount to a loss. The mineral impurity particles produced by the invention avoid the high-temperature sintering process of the mineral impurity particles, but retain the existence form of the ancient original ecology, and reduce it to near the ancient soil through a series of biochemical processes. The form, then used as a plant mineral trace element compound fertilizer, or as a carrier to further load other plant nutrients and used as a fertilizer, is precisely a creative new way to turn waste into treasure and maximize the utilization of coal resources.

DRAWINGS

1 is a process flow diagram of a process for producing high calorific value coal water slurry using coal or coal gangue according to the present invention.

Fig. 2 is a schematic view showing the structure of a nano-micro separation apparatus used in the present invention.

Fig. 3 is a schematic view showing a typical process flow of coal water slurry gasification before the present invention.

4 is a schematic view showing an improved process flow of coal water slurry gasification which can effectively utilize inferior coal by using the micro/nano separation technology of the present invention.

Detailed ways

The contents of the present invention are further illustrated by the following examples, but are not intended to limit the invention.

Example 1

The inferior coal used is peat with a mineral content of 30wt%, which is transported to the crusher for preliminary crushing, and then introduced into a wet mill to grind to a particle size of less than 50 microns. Water and additives are added for wet grinding and pulping. . The prepared coal water slurry is stored in a coal water slurry storage tank, and the amount of the coal water slurry is controlled by a coal water slurry weighing instrument. The coal water slurry is conveyed to the micro/nano separation device through a coal water slurry feed pump and a coal water slurry transfer line at a pumping pressure of 0.3 MPa.

The separation principle of micro-nano separation equipment is based on the difference of particle surface properties and the interference settlement principle of particles in fluidized fluid. The composite force field is used to separate the separation of hydrocarbon combustible material particles and mineral impurity particles. The structure is as shown in FIG. 2, and the coal water slurry 1 stirred by the micro-nano additive is fed from the upper part of the equipment to the ore distributor 2, and uniformly sent to the micro-nano separation column 3, according to the micro-nano separation column 3 The section moves slowly downwards. The high-pressure gas 7 is pressed into the oil-containing bubble generator 5 by an air compressor; at the same time, the hydrophobic auxiliary agent 6 is injected into the oil-containing bubble generator 5, and micro-nano bubbles containing the hydrophobic auxiliary agent 6 are formed inside the oil-containing bubble generator 5. The generated bubbles having a diameter of less than 100 μm are fed from the microbubble distributor 4 at the bottom of the micro-nano separation column 3, and the rising bubbles collide with the descending particles and uniformly spread over the surface of the hydrocarbon combustible material particles, thereby Make it a mineralized bubble. Thus, a dynamic collision and separation environment of bubbles and particles is constructed inside the micro-nano separation column 3. The hydrophobic ore particles are attached to the bubbles and rise to the foam layer along with the bubbles, and are discharged through the collecting device 8 to obtain clean micro-nano hydrocarbon solid fuel particles 9; and the mineral particles are hydrophilic ore particles under gravity The bottom stream 10 is discharged as tailings to achieve effective separation. The micro-nano separation column 3 is typically divided into two zones: a capture zone between the foam-slurry interface and the bubble generator, and a selection zone between the foam-slurry interface and the overflow. In the capture zone, mainly the bubble mineralization process, while the selection zone is the secondary enrichment of the mineralized foam, and the addition of the rinse water 11 further eliminates the mechanical impurities entrained in the foam.

After separating the carbon-hydrogen-containing combustible particles from the foam, the mixture has been subjected to pressure filtration, mixing and adding some conventional additives to prepare a solid content of not less than 60% by weight and a calorific value of not less than 4500 kcal/kg. The suspended coal-water slurry is suspended, and then the coal-water slurry is conveyed to the gasifier through a coal-water slurry feed pump and a coal-water slurry transfer line. The typical coal water slurry gasification process in the prior art is shown in FIG. The improved process flow of coal water slurry gasification using the micro/nano separation technology of the present invention, which can effectively utilize inferior coal and by-product micro-mineral compound fertilizer is shown in FIG. 4 . In the gasifier, the coal water slurry is blended with the air separation oxygen to gasify, and the gasification furnace process and equipment parameters are adjusted to achieve the optimal state to produce syngas. The syngas enters the waste heat boiler or the chilling device, and the waste heat of the gasification gas is fully utilized by the influent water and the high pressure steam circulation system, and the ash is automatically discharged through the lock control. The raw syngas produced is washed by a water washing tower to discharge gray water, and finally the raw syngas which can satisfy the production of downstream products is produced. The underflow product of the micro-nano separation equipment enters the concentrated sedimentation tank, the bottom of the sedimentation tank enters the filter press, the flocculant is added for pressure filtration dehydration, the feed volume of the filter press is monitored, and the sedimentation tank overflows with the filter press filtrate into the circulating water. System reuse. The filter cake of the filter press enters the biochemical reaction tank, adjusts the nitrogen, phosphorus and potassium required by the plant and the necessary trace elements according to the market application requirements. Each addition amount is monitored by the weighing system in real time, and a series of biochemical processes such as fermentation of beneficial bacteria are carried out. Finally, the production of micro-mineral compound fertilizer.

Example 2

The inferior coal used is a lignite having a mineral content of 20% by weight, which is sent to a crusher for preliminary crushing, and then introduced into a wet mill to be ground to a particle size of less than 450 μm, and water and additives are added for wet grinding and slurrying. The prepared coal water slurry is stored in a coal water slurry storage tank, and the amount of the coal water slurry is controlled by a coal water slurry weighing instrument. The coal water slurry is conveyed to the micro/nano separation device through a coal water slurry feed pump and a coal water slurry transfer line at a pumping pressure of 0.3 MPa.

The device and method of operation as shown in Figure 2 are still employed. The bubbles used for micro-nano separation are less than 200 microns in diameter. After separating the hydrocarbon combustible material particles from the foam, a conventional solid additive may be added to prepare a suspension-stable coal water slurry having a solid content of not less than 60% by weight and a calorific value of not less than 4100 kcal/kg. . The process of coal water slurry transport, gasification reaction process and micro-mineral compound fertilizer are the same as in the first embodiment.

Example 3

The coal gangue used is a washed coal with a mineral content of 40% by weight, which is sent to a crusher for preliminary crushing, and then introduced into a wet mill to be ground to a particle size of less than 100 μm, and water and additives are added for wet grinding. Pulp. The prepared coal water slurry is stored in a coal water slurry storage tank, and the amount of the coal water slurry is controlled by a coal water slurry weighing instrument. The coal water slurry is conveyed to the micro/nano separation device through a coal water slurry feed pump and a coal water slurry transfer line at a pumping pressure of 0.3 MPa.

The device and method of operation as shown in Figure 2 are still employed. The bubbles used for micro-nano separation are less than 80 microns in diameter. After separating the hydrocarbon combustible material particles from the foam, a conventional solid additive may be added to prepare a suspension-stable coal water slurry having a solid content of not less than 58% by weight and a calorific value of not less than 4000 kcal/kg. . The process of coal water slurry transport, gasification reaction process and micro-mineral compound fertilizer are the same as in the first embodiment.

Example 4

The coal gangue used is a slime having a mineral content of 50% by weight, which is sent to a crusher for preliminary crushing, and then introduced into a wet mill to be ground to a particle size of less than 50 μm, and water and additives are added for wet grinding and slurrying. . The prepared coal water slurry is stored in a coal water slurry storage tank, and the amount of the coal water slurry is controlled by a coal water slurry weighing instrument. The coal water slurry is conveyed to the micro/nano separation device through a coal water slurry feed pump and a coal water slurry transfer line at a pumping pressure of 0.3 MPa.

The device and method of operation as shown in Figure 2 are still employed. The bubbles used for micro-nano separation are less than 80 microns in diameter. After separating the hydrocarbon combustible material particles from the foam, a conventional solid additive may be added to prepare a suspension-stable coal water slurry having a solid content of not less than 56% by weight and a calorific value of not less than 4000 kcal/kg. . The process of coal water slurry transport, gasification reaction process and micro-mineral compound fertilizer are the same as in the first embodiment.

Example 5

The coal gangue used is coal gangue with a mineral content of 70wt%, which is transported to the crusher for preliminary crushing, and then introduced into a wet mill to grind to a particle size of less than 30 microns, and water and additives are added for wet grinding and slurrying. . The prepared coal water slurry is stored in a coal water slurry storage tank, and the amount of the coal water slurry is controlled by a coal water slurry weighing instrument. The coal water slurry is conveyed to the micro/nano separation device through a coal water slurry feed pump and a coal water slurry transfer line at a pumping pressure of 0.3 MPa.

The device and method of operation as shown in Figure 2 are still employed. The diameter of the bubbles used for micro-nano separation is less than 30 microns. After separating the hydrocarbon combustible material particles from the foam, a conventional solid additive may be added to prepare a suspension-stable coal water slurry having a solid content of not less than 55 wt% and a calorific value of not less than 4000 kcal/kg. . The process of coal water slurry transport, gasification reaction process and micro-mineral compound fertilizer are the same as in the first embodiment.

The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the foregoing embodiments, and that the description of the embodiments and the description of the present invention are not intended to limit the scope of the invention in any way, without departing from the scope of the invention. There are various changes and modifications to the invention that fall within the scope of the claimed invention.

Claims

A process for producing high calorific value coal water slurry using coal or coal gangue, wherein the coal or coal gangue comprises non-combustible minerals and carbon-hydrogen containing combustibles, characterized in that the process comprises the following steps:

A. Wetly grind coal or coal gangue in water until the average particle size of the particles is less than 500 microns. Add the additive in the coal water slurry to make it fully mix and disperse evenly during the wet grinding process to obtain the micro-nano coal containing the additive. Pulp

B. introducing microbubbles having a diameter of less than 200 micrometers into the micro-nano coal slurry containing the additive, wherein the mineral particles adhering to the additive are agglomerated and sink as an underflow, wherein the carbon-hydrogen-containing combustibles The particles float up with the bubbles to become a floating stream, thereby separating the carbonaceous-hydrogen-containing combustible particles from the mineral particles;

C. The carbon-hydrogen-containing combustible particles are separated from the floating stream, and are subjected to pressure filtration to prepare a high calorific value coal water slurry having a calorific value higher than 4000 kcal/kg.
The method according to claim 1, wherein the additive is a hydrophilic nanoparticle, a collector or a surfactant, wherein the hydrophilic nanoparticle is an aluminosilicate nanoparticle, preferably passed Preparing the mineral particles separated in step B to further mill to a nanometer scale range; wherein the collector is an organic thio compound. Preferably, an alkali metal alkyl dithiocarbonate; wherein the surface The active agent is a surface active molecule having a hydrophilic group and a hydrophobic group, and is preferably a terpineol oil, a camphor oil, a phenolic acid mixed fatty alcohol, an isomeric hexanol, an octanol, an ether alcohol, or an ester.
The method of claim 1 wherein said additive further comprises:

pH adjusting agents such as lime, sodium carbonate, sodium hydroxide and sulfuric acid; and,

Flocculants such as polyacrylamide and starch.
The method according to claim 1, characterized in that in step A the coal or coal gangue is comminuted to an average particle size of less than 500 microns, preferably less than 400 microns, preferably less than 300 microns, preferably less than 200 microns, preferably Particles of less than 100 micrometers, preferably less than 50 micrometers, preferably less than 20 micrometers, preferably less than 10 micrometers, preferably less than 5 micrometers; in step B the microbubbles have a diameter of from several micrometers to 200 micrometers, preferably several micrometers to several tens Micrometers, more preferably the diameter of the microbubbles is in the range of 50% to 200% of the average particle size of the coal or coal gangue particles.
The method according to claim 1, further comprising the step D: using the mineral particles separated by the step C as a raw material for the micro-mineral compound fertilizer.
The method of claim 1 wherein said coal is selected from the group consisting of: high quality coal having a calorific value of more than 4500 kcal/kg, or inferior coal having a calorific value of less than 4500 kcal/kg. The inferior coal includes washed coal or slime or coal gangue.
A high calorific value coal water slurry characterized in that its calorific value is higher than 4000 kcal/kg, and its solid content of combustibles is higher than 55 wt%, preferably higher than 60 wt%, based on the percentage of dry basis; its ash content is lower than 10% by weight, preferably less than 5% by weight; wherein the carbon-hydrogen-containing combustible particles have a particle size of less than 500 microns, preferably less than 400 microns, preferably less than 300 microns, preferably less than 200 microns, preferably less than 100 microns, preferably less than 50 Particles of micron, preferably less than 20 microns, preferably less than 10 microns, preferably less than 5 microns.
The high calorific value coal water slurry according to claim 7, which is produced by the process of claim 1.
Use of the high calorific value coal water slurry according to claim 7 as a raw material for a coal gasification process, which is used for one or a combination of the following uses: using inferior coal or coal gangue as a raw material, reducing oxygen consumption, reducing energy consumption or increasing gas The use of the high calorific value coal water slurry of claim 7 as a coal water slurry boiler fuel for reducing nitrogen oxides, sulfur oxides and/or particulate matter emissions from boilers.
A coal gasification process characterized by comprising the steps of:

A. Using the process according to claim 1, using coal or coal gangue to produce high calorific value coal water slurry;

B. The high calorific value coal water slurry is sent to a gasification furnace for gasification.