Coal water slurry prepared from epoxy resin wastewater as well as preparation method and application of coal water slurry

Abstract

The invention discloses coal water slurry prepared from epoxy resin wastewater and a preparation method and application of the coal water slurry, and the coal water slurry comprises the following components in parts by weight: 225-600 parts of mixed coal; 150 to 400 parts of epoxy resin wastewater; 0.1 to 10 parts of an additive; the mixed coal is composed of bituminous coal and anthracite, and the weight ratio of the bituminous coal to the anthracite is (1-5): (1-5). The epoxy resin wastewater is used for replacing fresh water, anthracite and bituminous coal are mixed, the prepared coal water slurry has no corrosion to a rod mill and is good in slurrying property and high in ash fusion point, the water-cooled wall gasification furnace is used for gasifying the coal water slurry, the gasification reaction temperature is high, oxygen consumption is low, the carbon conversion rate is high, the COD content of external gasification sewage of the gasification furnace and the sewage discharge amount are low, and the coal water slurry can be recycled. The method has the advantages of realization of the resource utilization of the epoxy resin wastewater, improvement of the adaptive capacity of coal types, no environmental pollution, environmental protection, and generation of important economic values and social benefits.

Description

Technical Field

[0001] The invention relates to a water-coal slurry prepared by utilizing epoxy resin wastewater, a preparation method and application thereof, and belongs to the technical field of petrochemical industry. Background Art

[0002] Epoxy resin is an important type of thermosetting resin, characterized by excellent physical and mechanical properties, chemical resistance, electrical insulation, heat resistance, and adhesive properties. It is widely used in various fields, particularly composite materials, electronics, and coatings. These three areas currently account for approximately 80% of global epoxy resin applications.

[0003] At present, the treatment technologies for epoxy resin high-concentration salt-containing wastewater can be roughly divided into two categories. One is a simple treatment process that does not consider the recovery and reuse of useful resources such as salt or toluene, such as incineration, activated carbon adsorption, and ordinary biochemical treatment technology membrane bioreactors. The other is a treatment technology with recovery and available resources as the main process, such as closed-loop process to recover salt and toluene, multi-stage evaporation recovery salt process spray, drying dilute salt, etc. Comparing the two types of treatment, it is generally agreed that the idea of ​​recycling available resources is more reasonable. In particular, for the high salt content of epoxy resin wastewater, salt precipitation and recycling can not only reduce the treatment cost but also facilitate the subsequent biochemical treatment to proceed normally and meet the effluent discharge standards. However, the traditional evaporation crystallization recovery has high energy consumption and high operating costs, resulting in high treatment costs. The pretreatment cost of each ton of epoxy resin wastewater is about 200 yuan.

[0004] Since 1990, coal-water slurry gasification technology has developed rapidly, and a coal-water slurry gasification technology for high-concentration wastewater has been successfully developed. For example, CN105505471A discloses a coal-water slurry gasification process suitable for treating high-concentration ammonia nitrogen and COD wastewater. This method grinds a mixture of bituminous coal, wastewater, and additives in a ball mill to produce a coal-water slurry. The slurry is then pressurized by a high-pressure coal slurry pump and fed into a coal-water slurry gasifier to undergo an incomplete oxidation reaction with pure oxygen. The organic matter in the wastewater and the organic matter in the coal undergo an incomplete oxidation reaction at a gasification temperature of 1300-1400°C and a gasification pressure of 2-3 MPa g to produce high-pressure crude coal gas, the main gas components of which are carbon monoxide, hydrogen, methane, and carbon dioxide. The advantage of this method is that it can treat high-concentration organic waste liquid (COD content 100,000 mg / L). The disadvantage is that the gasification reaction temperature is relatively low, and the COD content in the gasified wastewater discharged from the gasifier itself is 800-1300 mg / L. The wastewater discharge is large and requires further treatment at an external sewage treatment plant. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the first purpose of the present invention is to provide a water-coal slurry prepared using epoxy resin wastewater. The present invention uses epoxy resin wastewater instead of fresh water and mixes anthracite and bituminous coal. The prepared water-coal slurry does not corrode the rod mill, has good slurrying properties and a high ash melting point, and uses a water-cooled wall gasifier to gasify the water-coal slurry. The gasification reaction temperature is high, the oxygen consumption is low, and the carbon conversion rate is high. The COD content and sewage discharge of the gasifier itself are low, which realizes the resource utilization of epoxy resin wastewater while improving the adaptability of coal types.

[0006] The second object of the present invention is to provide a method for preparing water-coal slurry using epoxy resin wastewater.

[0007] The third object of the present invention is to provide an application of water-coal slurry prepared by utilizing epoxy resin wastewater.

[0008] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0009] The present invention provides a coal-water slurry prepared by utilizing epoxy resin wastewater, which comprises the following components in parts by weight:

[0010] 225-600 parts of mixed coal;

[0011] 150-400 parts of epoxy resin wastewater;

[0012] 0.1 to 10 parts of additives;

[0013] The mixed coal consists of bituminous coal and anthracite, and the weight ratio of the bituminous coal to the anthracite is 1-5:1-5.

[0014] The water-coal slurry provided by the present invention uses epoxy resin wastewater instead of fresh water. With the cooperation of the above components and proportions, not only the slurrying performance and ash content of the water-coal slurry are qualified, but also the epoxy resin wastewater does not need to be treated, which greatly reduces the cost.

[0015] The slurrying properties of water-coal slurry are usually related to the properties of coal and water. Compared with fresh water, the slurrying properties of wastewater are worse when using the same type of coal because wastewater contains some inorganic salts. Specifically, when achieving the same coal slurry viscosity (<1200mPa·s), the dry basis concentration of water-coal slurry prepared with wastewater is 1 to 2 percentage points lower than that of water-coal slurry prepared with fresh water.

[0016] When the same amount of fresh water or wastewater is used, the internal water content of coal has a greater impact on the slurry performance of water-coal slurry. Generally speaking, the internal water content of coal is required to be less than 6% to produce qualified water-coal slurry, that is, the viscosity is less than 1200mPa·s, the dry basis coal slurry concentration is 60.1%~70.0%, and the ash content Aad is 8%-20%.

[0017] The coal-water slurry gasification industry usually uses bituminous coal from the Shenfu coalfield to prepare coal-water slurry. The characteristics of bituminous coal are: (1) The internal water Mad is relatively high, fluctuating between 4-10%. This causes the dry basis concentration of the coal-water slurry prepared with bituminous coal to fluctuate around 60.1%, and it cannot reliably prepare coal-water slurry with qualified slurry performance, but it can ensure that the ash content is qualified; (2) The ash content Aad is low (<8%): When wastewater is used instead of fresh water to prepare coal-water slurry with the bituminous coal from the Shenfu coalfield, the dry basis concentration of the coal slurry further decreases, reducing the economic benefits of gasification.

[0018] The characteristics of anthracite are: (1) low internal water content Mad (<2%); (2) high ash content Aad, fluctuating between 20% and 28%. Therefore, anthracite can be used to reliably produce water-coal slurry with qualified slurry properties but unqualified ash content.

[0019] The inventors discovered that by using a mixture of anthracite and bituminous coal and controlling the ratio of anthracite to bituminous coal within the scope of the present invention, and when wastewater is used instead of fresh water to prepare water-coal slurry with the bituminous coal from the Shenfu coalfield, a water-coal slurry with qualified slurrying properties and ash content can be prepared through the synergistic effect between the components.

[0020] Preferably, the coal-water slurry comprises the following components in parts by weight:

[0021] 225-600 parts of mixed coal;

[0022] 150-400 parts of epoxy resin wastewater;

[0023] Additives 0.1-1 parts;

[0024] Preferably, in the mixed coal, the weight ratio of bituminous coal to anthracite is 1 to 3:1.

[0025] Preferably, the blended coal has an ash content (Aad) of 8% to 20%, an ash melting point of 1300°C to 1450°C, and an internal water content (Mad) of ≤6%. In the present invention, the ratio of bituminous coal to anthracite is controlled within the scope of the present invention, so that the properties of the resulting blended coal are within the above-mentioned ranges, ultimately producing a water-coal slurry with good slurrying properties and a qualified ash content.

[0026] Preferably, the epoxy resin wastewater refers to wastewater generated by the epoxy resin process.

[0027] Preferably, the additive is selected from sodium lignin sulfonate. In the present invention, adding a small amount of additives can reduce the surface tension of water and increase the surface tension of coal powder, so that polar water and non-polar coal powder can penetrate each other to form a stable suspension.

[0028] Preferably, the water-coal slurry further comprises limestone powder, and the amount of the limestone powder added is 0-3.5 wt %, preferably 1-3 wt %, of the mixed coal weight.

[0029] The ash melting point of anthracite is usually greater than 1500°C, and the ash melting point of bituminous coal is usually 1180-1380°C. The present invention uses limestone as a flux, which can be reasonably added according to the mixed coal components in the actual process to lower the ash melting point of the mixed coal.

[0030] Further preferably, the median particle size of the limestone powder is 5 to 50 μm.

[0031] Preferably, the pH value of the coal-water slurry is 6.30-10.73; the chloride ion content is <0.05 mg / L.

[0032] Preferably, the dry basis coal slurry concentration of the water-coal slurry is 60.1% to 70.0%, the viscosity is less than 1200 mPa·s, the ash content Aad is 8 to 20%, and the dry basis coal slurry median diameter D50 is 26.53-33.50 μm.

[0033] Preferably, the dry basis concentration of the coal slurry (theoretical value) is 60.6%; the dry basis concentration of the coal slurry (measured value) is 59.0-71.8%; the density of the water-coal slurry is 1.100-1.149 g / cm 3 .

[0034] The invention discloses a method for preparing water-coal slurry using epoxy resin wastewater. Bituminous coal, anthracite, epoxy resin wastewater and additives are mixed according to a designed ratio and fed into a water-coal slurry mill for grinding to obtain water-coal slurry with a median particle size of 26.53-33.50 μm.

[0035] The present invention discloses an application of water-coal slurry prepared by using epoxy resin wastewater, wherein the water-coal slurry is sent to a water-cooled wall gasifier to undergo a gasification reaction to produce synthesis gas, with a gasification temperature of 1450-1600°C and a gasification pressure of 3.0-7.0 MPag.

[0036] In a preferred solution, the COD removal rate of epoxy resin wastewater after gasification reaction is 98.0-99.9%, the carbon conversion rate in mixed coal is 97.0-99.5%, and the COD content of gasified wastewater discharged from the gasifier itself is 100-500 mg / L.

[0037] Principles and advantages

[0038] The present invention discloses a coal-water slurry prepared from epoxy resin wastewater and a preparation method thereof. The slurry comprises the following components, by weight: 225-600 parts of mixed coal; 150-400 parts of epoxy resin wastewater; and 0.1-10 parts of an additive. The mixed coal comprises bituminous coal and anthracite, with the weight ratio of bituminous coal to anthracite being 1-5:1-5. The present invention replaces fresh water with epoxy resin wastewater and mixes anthracite with bituminous coal. The resulting coal-water slurry is non-corrosive to rod mills, exhibits excellent slurrying properties, and has a high ash melting point. The coal-water slurry is gasified in a water-cooled wall gasifier, resulting in a high gasification reaction temperature, low oxygen consumption, and high carbon conversion rate. The gasifier also produces low COD content and wastewater discharge from the gasifier itself. This method not only achieves resource utilization of epoxy resin wastewater but also improves coal adaptability. Furthermore, the slurry does not cause environmental pollution, is environmentally friendly, and generates significant economic and social benefits.

[0039] The present invention does not require the addition of additional raw and auxiliary materials, does not require wastewater recovery and treatment processes, and does not impact the environment. It fully utilizes the wastewater generated by the epoxy resin device, reduces wastewater discharge, and achieves the reuse of wastewater resources, which is environmentally friendly.

[0040] The advantages of the present invention are:

[0041] 1. The present invention obtains water-coal slurry by mixing epoxy resin wastewater with raw coal, which can meet the quality requirements of the water-coal slurry gasification furnace for the raw materials entering the furnace. There is no need to add other raw and auxiliary materials, and there is no need to set up wastewater recovery and treatment processes. It is simple and efficient.

[0042] 2. The present invention obtains water-coal slurry by mixing epoxy resin wastewater with raw coal, which can make epoxy resin wastewater resources into crude coal gas and use it as raw material for chemical enterprises or civilian fuel without affecting the environment, thus generating excellent economic and social benefits.

[0043] 3. The present invention obtains water-coal slurry by mixing epoxy resin wastewater with raw coal, which can make the fluidity of gas-water-coal slurry reach Class A, reuse the wastewater generated by the epoxy resin device, do not cause waste of organic matter and secondary environmental pollution, and do not affect the operation of the existing high-temperature and high-pressure entrained flow water-coal slurry gasification device.

[0044] 4. The present invention obtains water-coal slurry by mixing epoxy resin wastewater with raw coal, fully utilizing the wastewater generated by the epoxy resin device, realizing maximum utilization of epoxy resin wastewater resources and truly achieving clean production.

[0045] 5. The present invention obtains water-coal slurry by mixing epoxy resin wastewater with raw coal, thereby changing the composition of the raw coal of the gasifier, making the prepared raw coal meet the requirements of the coal gasification device, and expanding the range of raw materials for coal gasification. DETAILED DESCRIPTION

[0046] The present invention will be further described below by way of examples, which are not intended to further limit the present invention. Those skilled in the art will appreciate that any equivalent substitutions or corresponding improvements made to the technical features of the present invention are still within the scope of protection of the present invention.

[0047] Example 1

[0048] The test items and analysis methods are as follows:

[0049] Determination of concentration of coal water slurry GB / T 18856.2-2008

[0050] Determination of density of coal-water slurry GB / T 18856.6-2008

[0051] Dry basis coal slurry particle size D50 GB / T 19077.1 Laser particle size analyzer method

[0052] Determination of pH value of coal-water slurry GB / T 18856.7

[0053] Determination of apparent viscosity of coal-water slurry GB / T 18856.4 Rotational viscometer method

[0054] Coal-water slurry stability determination, rod insertion observation method

[0055] After the slurry is formed, it is left to stand for 15 hours. The stability index is tested and classified into the following four categories:

[0056] Grade A - indicates the best stability. The slurry is evenly distributed, has no water absorption or precipitation, and flows as before after stirring.

[0057] Grade B - indicates good stability, no precipitation or a small amount of soft precipitation, with very little water absorption and slight uneven distribution of slurry.

[0058] Grade C - indicates poor stability, with dense and uneven distribution of water-absorbing slurry and serious sedimentation, but it can be regenerated into a uniform slurry after stirring.

[0059] Grade D - indicates the worst stability. The slurry is dense and obviously unevenly distributed. It absorbs a lot of water and precipitates hard, and cannot be regenerated.

[0060] The fluidity is determined by visual inspection and is divided into 4 grades: A, B, C, and D. Each grade is divided as follows:

[0061] Class A - Thin fluid flows continuously, smoothly and without interruption.

[0062] Class B - Thick fluid flows more continuously and the fluid surface is not smooth.

[0063] Grade C - Flows well with the help of external force.

[0064] Grade D - muddy, does not sink, and cannot flow.

[0065] '+' and '-' are used to indicate finer distinctions between levels.

[0066] Epoxy resin salt-containing wastewater, raw coal, a certain amount of additives, and limestone powder are mixed and ground into water-coal slurry. The raw coal is obtained by mixing 081 anthracite and 152 bituminous coal in a weight ratio of 1:3. The specifications of various materials are shown in Table 1, and the specific formula is shown in Table 2.

[0067] Table 1 Specifications of coal water slurry materials

[0068] raw materials Specification Remark Pulverized coal samples 081:152(1:3) Grind into powder 1# Wastewater New liquid epoxy resin wastewater 2# wastewater 40,000 tons of resin wastewater 3# wastewater Phenolic resin wastewater 4# wastewater Epoxy plant resin wastewater additive Sodium lignin sulfonate (solid) Outsourcing

[0069] Table 2 Coal-water slurry formula

[0070]

[0071] The pH value and chloride ion content of the wastewater are shown in Table 3; the test results of the water-coal slurry performance are shown in Table 4

[0072] Table 3 pH value and chloride ion content of wastewater

[0073] project 1# 2# 3# 4# pH 13.74 13.50 0.74 13.09 Chloride ion content, mg / L ＜0.05 ＜0.05 ＜0.05 0.29

[0074] Table 4 Coal water slurry performance test results

[0075]

[0076] The coal slurry test shows that the phenolic resin wastewater; epoxy line wastewater; new liquid resin wastewater and 40,000 tons of resin wastewater are made into water-coal slurry with a concentration of 60% to 61%, and the stability is A — C; fluidity is A; meets the requirements of the fluidized flow water-cooled wall water-coal slurry gasification furnace for the raw materials entering the furnace.

[0077] Add limestone powder and additives to the new liquid epoxy resin wastewater and raw coal in the above proportions, send them into the coal water slurry mill and grind them into coal slurry with a particle size of 26.53-33.50μm, and send them into the entrained flow coal water slurry water-cooled wall gasifier at 0.6Nm 2 / kg raw material (dry basis) is added with pure oxygen to carry out gasification reaction. The gasification reaction pressure is controlled at 6.5MPaG and the gasification reaction temperature is 1450-1600℃, wherein most of the carbon is converted into effective components carbon monoxide and hydrogen, a small amount is converted into carbon dioxide, and the sulfur is converted into hydrogen sulfide.

[0078] The following chemical reactions mainly take place in the gasifier:

[0079]

[0080] The data of wastewater discharged from the gasifier itself is shown in Table 4:

[0081] Table 4

[0082]

[0083] Comparative Example 1

[0084] Other conditions are the same as those in Example 1. The mixed coal, fresh water, flux and additives are mixed in a set ratio and then ground evenly in a rod mill to produce water-coal slurry, which wastes water resources and is not environmentally friendly.

[0085] It can be seen that by adopting the solution of the present invention, the wastewater generated by the epoxy resin device is used as water for slurrying of water-coal slurry, which not only saves more than 3 million yuan in epoxy resin wastewater pretreatment costs each year, but also greatly reduces the consumption of fresh water resources, making it more green and environmentally friendly.

Claims

1. A coal-water slurry prepared using epoxy resin wastewater, characterized by: Calculated by weight, it includes the following components: 225-600 parts of mixed coal; 150-400 parts of epoxy resin wastewater; 0.1 to 10 parts of additives; The mixed coal consists of bituminous coal and anthracite, and the weight ratio of the bituminous coal to the anthracite is 1-5:1-5.

2. The coal-water slurry prepared using epoxy resin wastewater according to claim 1, characterized in that: In the mixed coal, the weight ratio of bituminous coal to anthracite is 1 to 3:

1.

3. The coal-water slurry prepared using epoxy resin wastewater according to claim 1, characterized in that: The mixed coal has an ash content Aad of 8% to 20%, an ash melting point of 1300 to 1450° C., and an internal water content Mad≤6%.

4. The coal-water slurry prepared using epoxy resin wastewater according to any one of claim 1, characterized in that: The epoxy resin wastewater refers to the wastewater generated by the epoxy resin process.

5. The coal-water slurry prepared using epoxy resin wastewater according to any one of claims 1 to 4, characterized in that: The additive is selected from sodium lignin sulfonate.

6. The coal-water slurry prepared using epoxy resin wastewater according to any one of claims 1 to 4, characterized in that: The water-coal slurry further contains limestone powder, wherein the amount of the limestone powder added is 0 to 3.5 wt% of the weight of the mixed coal; The median particle size of the limestone powder is 5 to 50 μm.

7. The coal-water slurry prepared using epoxy resin wastewater according to any one of claims 1 to 4, characterized in that: The pH value of the coal water slurry is 6.30-10.73; the chloride ion content is less than 0.05 mg / L; The dry basis coal slurry concentration of the water-coal slurry is 60.1% to 70.0%, the viscosity is less than 1200 mPa·s, the ash content Aad is 8 to 20%, and the dry basis coal slurry median diameter D50 is 26.53 to 33.50 μm.

8. The method for preparing coal-water slurry using epoxy resin wastewater according to any one of claims 1 to 7, characterized in that: Bituminous coal, anthracite, epoxy resin wastewater and additives are mixed according to the designed proportion and sent into a water-coal slurry mill for grinding until a water-coal slurry with a median particle size of 26.53-33.50 μm is obtained.

9. The use of a coal-water slurry prepared using epoxy resin wastewater according to any one of claims 1 to 7, characterized in that: The water-coal slurry is sent to a water-cooled wall gasifier to undergo a gasification reaction to produce synthesis gas. The gasification temperature is 1450-1600° C. and the gasification pressure is 3.0-7.0 MPag.

10. The use of coal water slurry prepared by using epoxy resin wastewater according to claim 9, characterized in that: The COD removal rate of epoxy resin wastewater after gasification reaction is 98.0-99.9%, the carbon conversion rate in mixed coal is 97.0-99.5%, and the COD content of gasified wastewater discharged from the gasifier itself is 100-500 mg / L.

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