CN110903841B

CN110903841B - Preparation and utilization method of oil-rich coal in-situ pyrolysis solid heat carrier

Info

Publication number: CN110903841B
Application number: CN201911225828.6A
Authority: CN
Inventors: 张蕾; 贾阳; 石智军; 王晓康; 齐凌博; 尚进
Original assignee: Xian University of Science and Technology
Current assignee: Xian University of Science and Technology
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2022-03-29
Anticipated expiration: 2039-12-04
Also published as: CN110903841A

Abstract

The invention belongs to the field of coal chemical utilization and solid waste recycling, and particularly relates to a preparation and utilization method of an oil-rich coal in-situ pyrolysis solid heat carrier. The solid heat carrier for in-situ pyrolysis of the oil-rich coal is prepared by taking CaO, iron ore and blast furnace slag as raw materials, mixing the raw materials in a proper proportion under a certain granularity, and pumping the mixture into an underground pre-cracked coal bed through a high-pressure pump, so that the solid heat carrier plays a role of a heat carrier when the oil-rich coal is subjected to in-situ pyrolysis, the heating uniformity of the coal bed is improved, and the pyrolysis reaction is ensured; the rich-oil coal is pyrolyzed to generate more tar through the catalytic property of the metal oxide; the light degree of tar is improved during secondary cracking, and the proportion of light oil is increased; and for NO produced by the pyrolysis process_X、SO₂And H₂S and other gas pollutants have the functions of catalysis and fixation, so that the gas pollutants are prevented from polluting the atmospheric environment.

Description

Preparation and utilization method of oil-rich coal in-situ pyrolysis solid heat carrier

Technical Field

The invention belongs to the field of coal chemical utilization and solid waste recycling, and particularly relates to a preparation and utilization method of an oil-rich coal in-situ pyrolysis solid heat carrier.

Background

The conversion and utilization of coal is an important way for supplementing oil and gas resources, and mainly comprises coal gasification, coal liquefaction and coal dry distillation (pyrolysis). Although the coal gasification and coal liquefaction have single product and high purity, the energy consumption caused by the coal gasification and coal liquefaction is high. The dry distillation technology of coal is a mature technology with low energy consumption, and is heated and decomposed into three-phase products of coke, coal tar and coal gas in an anoxic or anaerobic atmosphere. In a conventional mode, pyrolysis in a certain reactor, such as a fixed bed reactor, a fluidized bed reactor and the like, needs to be carried out in a certain container to produce coal tar. Therefore, in order to improve the pyrolysis efficiency and yield, the oil and gas resources are extracted from underground in-situ pyrolysis rich coal. However, the in-situ pyrolysis technology of the oil-rich coal is not mature, and the problems that the coal pyrolysis heat is uniformly distributed in the conventional pyrolysis process, the coal thermal conductivity is poor, the coal tar pyrolysis yield is low, certain pollutant gas is generated in the pyrolysis process and the like exist.

Disclosure of Invention

Therefore, the invention provides a preparation and utilization method for an oil-rich coal in-situ pyrolysis solid heat carrier aiming at the problems of less tar, low quality, uneven pyrolysis temperature distribution and removal of pollutants generated in the pyrolysis process in the prior art, wherein the heat carrier and the utilization method can increase the stability and conductivity of heat transfer in the oil-rich coal in-situ pyrolysis process, so that heat brought by superheated steam is uniformly dispersed into a coal bed, and the pyrolysis effect of coal is improved; the heat carrier and the utilization method can play a role in catalyzing coal pyrolysis, and the yield of tar in the coal pyrolysis process is increased; the heat carrier and the utilization method can play a role in conditioning the coal tar generated by pyrolysis, and are beneficial to the lightening of the coal tar and the increase of the light oil proportion; the heat carrier can play a role in catalyzing performance and fixing acidic pollutants, and can be used for NO generated in the pyrolysis process of the oil-rich coal_X、SO₂And H₂The acidic polluted gases such as S and the like have the functions of catalytic conversion and fixed neutralization, and are prevented from rising to the ground along with tar to pollute the atmosphere.

The invention adopts the following scheme to solve the problems:

a solid heat carrier for in-situ pyrolysis of oil-rich coal comprises the following components in parts:

1 part of CaO;

3-4 parts of iron ore;

5-7 parts of blast furnace slag.

Preferably, the solid heat carrier for the in-situ pyrolysis of the oil-rich coal is prepared by mixing CaO and water, wherein the CaO is particles with the particle size of 3-10 mm.

Preferably, the solid heat carrier for the in-situ pyrolysis of the oil-rich coal is prepared from iron ore particles with the particle size of 2-10 mm.

Preferably, the solid heat carrier for in-situ pyrolysis of the oil-rich coal is prepared by using blast furnace slag particles with the particle size of 2-10 mm.

A preparation method of an oil-rich coal in-situ pyrolysis solid heat carrier comprises the following steps:

crushing CaO to obtain granulated CaO; crushing iron ore to obtain granulated iron ore; taking granulated blast furnace slag for later use;

1 part of granulated CaO, 3-4 parts of iron ore and 5-7 parts of blast furnace slag are mixed to prepare the solid heat carrier.

A method for carrying out in-situ pyrolysis on oil-rich coal by adopting any solid heat carrier.

Preferably, in the method for in-situ pyrolysis of oil-rich coal, the solid heat carrier is injected into a horizontal well of a fractured coal seam.

Therefore, compared with the prior art, the invention has the following advantages: (1) the invention provides an efficient heat carrier during in-situ pyrolysis of oil-rich coal, which can improve the uniformity of heating of a coal bed and ensure the implementation of pyrolysis reaction; (2) the invention leads the rich-oil coal to be pyrolyzed to generate more tar through the catalytic characteristic of the metal oxide; the light degree of tar is improved during secondary cracking, and the proportion of light oil is increased; (3) the present invention is directed to NO produced by a pyrolysis process_X、SO₂And H₂S and other gas pollutants have the functions of catalysis and fixation, so that the gas pollutants are prevented from polluting the atmospheric environment.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which,

FIG. 1 is a schematic diagram showing the mixing of a solid heat carrier in example 1 of the present invention;

FIG. 2 shows the arrangement positions of the solid heat carriers mixed in example 1 in a pre-fractured oil-rich coal seam.

In the figure, 1-CaO, 2-blast furnace slag, 3-iron ore, 4-production well, 5-heat injection well and 6-solid heat carrier.

Detailed Description

The method aims at solving the problems that the ground dry distillation technology has less tar, low quality, uniform pyrolysis temperature distribution and the pollutants generated in the pyrolysis process need to be removed. The scheme of the embodiment adopts an underground in-situ pyrolysis technology, so that the human and financial input and the environmental problems brought by coal mining can be reduced to the greatest extent. The underground pyrolysis technology of the oil-rich coal can reduce the front-end treatment process of the later coal chemical industry and the gas pollutant treatment equipment at the rear end, and can reduce the occupied area and protect the environment.

Coal pyrolysis is a reaction process coexisting in coal gasification, coal liquefaction and coal carbonization processes, and is a process in which a macromolecular structure of coal is precipitated from a structure of the coal and recombined into small molecules. The coal pyrolysis process is influenced by factors such as pyrolysis temperature, pyrolysis time and the like, the optimal temperature of tar generated by coal pyrolysis is 500-600 ℃, and therefore the problem of ensuring constant temperature is the core problem of pyrolysis oil production. In this embodiment, superheated steam is adopted as the heat source, can the homodisperse to the fracturing coal seam in, makes the pyrolysis of coal seam thermally equivalent. The added solid heat carrier is mainly used for catalytically pyrolyzing the oil-rich coal to generate more tar and improving the tar yield of the oil-rich coal.

Coal tar is an important product generated in the low-temperature pyrolysis process of coal, but the coal tar contains a large amount of heavy components, so that the coal tar cannot be directly utilized, and the heavy components are easy to condense and block pipelines when meeting cold. The CaO, the iron ore and the blast furnace slag adopted by the invention have good catalytic cracking effect, so that the heavy components are lightened. The harm brought by heavy components can be reduced while the utilization of tar is improved.

Because of the existence of pollution elements such as S, N in coal, the gas pollutants generated in the pyrolysis process need to be provided with a desulfurization and denitrification process after the pyrolysis process, and the economic cost and the environmental cost of treatment are increased. The CaO adopted by the embodiment scheme is an alkaline substance, and can neutralize and fix the acidic gas generated in the pyrolysis process in an underground coal bed, so that the cost is increased while the equipment is corroded along with the rising of pyrolysis tar and pyrolysis gas to the ground. Iron ore and blast furnace slag are substances with certain catalytic properties, and can convert generated acidic pollutants into substances with low toxicity or no toxicity.

The embodiment is described in detail below.

Example 1

The embodiment is based on the embodiment of the mixing proportion, the using method and the action of a solid heat carrier for in-situ pyrolysis of oil-rich coal, and comprises the following steps of:

(1) taking the heat carrier CaO100kg, crushing the heat carrier CaO under a jaw crusher, and screening and separating particles with the particle size of 5-10 mm for later use;

(2) taking 300kg of the heat carrier iron ore, crushing the heat carrier iron ore under a jaw crusher, and screening and separating particles with the particle size of 5-10 mm for later use;

(3) taking 700kg of the hot carrier blast furnace slag for later use;

(4) mixing the three solid heat carriers in a ratio of 1: 3: 7, pumping the mixed dry materials into a horizontal well of the fractured coal seam through a vertical well by a high-pressure pump.

Introducing superheated steam to heat the coal layer of the oil-rich coal, enabling the solid heat carrier to play a role, and enabling CaO and water to react to release heat to keep the temperature of the steam; after the iron ore absorbs heat, the temperature can be stabilized within a certain range for a long time, and the temperature and time of pyrolysis are ensured; the metal oxide in the blast furnace slag also has the effects of stabilizing the pyrolysis temperature and improving the oil production of the oil-rich coal. The tar generated after pyrolysis is subjected to catalytic cracking under the action of a solid heat carrier, heavy components are subjected to light-weight action, and the proportion of available light oil is increased. And finally, the solid heat carrier is used for fixing and removing acid gas generated by pollution elements in the coal in the pyrolysis process, so that subsequent environmental hazards are reduced, and the equipment treatment cost is saved.

The mixing schematic of the solid heat carrier in this example is shown in fig. 1.

The solid heat carrier mixed in fig. 2 in this embodiment is grouted and distributed at the distribution position in the pre-fractured oil-rich coal seam, so that the solid heat carrier is distributed in the coal seam of the horizontal well to play roles of the heat carrier and the catalyst.

Example 2

(1) taking the heat carrier CaO100kg, crushing the heat carrier CaO under a jaw crusher, and screening and separating particles with the particle size of 5-8mm for later use;

(2) taking 400kg of the heat carrier iron ore, crushing the heat carrier iron ore under a jaw crusher, and screening and separating particles with the particle size of 3-6 mm for later use;

(3) 500kg of blast furnace slag of the hot carrier is taken for standby;

(4) mixing the three solid heat carriers in a ratio of 1: 4: 5, pumping the mixed dry materials into a horizontal well of the fractured coal bed through a vertical well by a high-pressure pump.

Example 3

(1) taking the heat carrier CaO100kg, crushing the heat carrier CaO under a jaw crusher, and screening and separating particles with the particle size of 3-6 mm for later use;

(2) taking 300kg of the heat carrier iron ore, crushing the heat carrier iron ore under a jaw crusher, and screening and separating particles with the particle size of 2-5 mm for later use;

(3) taking 700kg of the hot carrier blast furnace slag, crushing the hot carrier blast furnace slag by using a jaw crusher, and screening and separating particles with the particle size of 1-3 mm for later use;

(4) mixing the three solid heat carriers in a ratio of 1: 3: and 7, adding 1000kg of water into the mixture according to the proportion, uniformly stirring, and pumping the mixed slurry into a horizontal well of a fractured coal bed through a vertical well by using a high-pressure pump.

Examples 1-3 all adopt in-situ pyrolysis of oil-rich coal to extract oil gas resources, increase the yield of tar and the proportion of light oil in secondary cracking of the tar in the pyrolysis process of the oil-rich coal, and make the coke after pyrolysis still remain in the underground coal bed. Not only can fully utilize oil and gas resources, but also can ensure that the reserved coke has the effect of supporting the upper and lower roof plates of the coal bed.

In the embodiment 1-3, on the premise of in-situ pyrolysis of the oil-rich coal, CaO, iron ore and blast furnace slag with certain content and proportion are added as solid heat carriers, so that the nonuniformity of heat conduction when water vapor is used as a heat source is compensated, the heat conductivity of the oil-rich coal is improved, the coal bed is uniformly heated and decomposed, and the tar yield is increased. And the solid heat carrier has the catalytic cracking effect at the same time, so that the heavy components in the tar can be lightened. In addition, CaO has a fixed effect on acidic pollutants generated in the coal pyrolysis process, iron ore has a certain effect on catalytic conversion of gaseous pollutants, and the feasibility of the CaO as a catalyst is determined by the metal oxide existing in blast furnace slag.

Reaction of calcium oxide with water to form Ca (OH)₂The steam shift reaction and the methanation reaction in the pyrolysis process are exothermic reactions, the released heat can be utilized by the coal pyrolysis process, and the slurry is injected in the pyrolysis process, so that the energy consumption required by pyrolysis can be reduced. The calcium oxide can excite the generation of activation sites, has a certain catalytic action, can reduce the apparent activation energy of the coal sample and the temperature range of each pyrolysis section, and enables the pyrolysis reaction of coal to be easier to carry out. The catalytic activity of CaO can catalyze the fracture of alkyl side chains in pyrolysis product tar macromolecules, can obviously increase the pyrolysis rate and degree of aromatic compounds in coal, has catalytic action on the dehydrogenation of a fatty structure, can increase the content of light components in tar, and can improve the quality of the tar. In the whole pyrolysis process, the calcium oxide can absorb carbon dioxide and hydrogen sulfide in the pyrolysis gas to generate calcium carbonate and calcium sulfide, the emission of acidic pollutants is reduced, and meanwhile, the generated calcium carbonate can be solidified with pyrolysis coke, so that the mechanical property of the coke is improved. The addition of the iron ore can reduce the activation energy of the pyrolysis of the oil-rich coal and the temperature range of each pyrolysis section to a certain extent, so that the pyrolysis reaction of the coal is easier to carry out. Meanwhile, the iron ore is a metal oxide, has good thermal conductivity, can improve the thermal conductivity of the solid heat carrier, increases the yield of the iron ore solid heat carrier to tar more within the temperature range of 500-600 ℃, and improves the mechanical property of coke because the iron ore particles and calcium oxide in slurry are coarse aggregates and are solidified with pyrolytic coke. The coal can generate acid pollution gas NO in the pyrolysis process_X、SO₂And H₂S, etc., Al contained in blast furnace slag₂O₃、Fe₂O₃Substances such as CaO, MgO, MnO and the like are metal oxides beneficial to denitration, so that the acidic pollutant gas can be fixed to achieve the aim of removing the acidic pollutant gas.

The effects of examples 1 to 3 were verified as follows. The heat transfer coefficient of the heat carrier is maximized by reducing the particle size of three different heat carriers and changing different proportions. For the heat carrier proportion in different embodiments, the oil yield of the oil-rich coal pyrolysis can be increased under the action of the heat carrier, and the main reason is that the heat conductivity of the heat carrier is superior to that of gas, so that the coal bed can be in the optimal pyrolysis temperature range. The effect of the three examples on the yield of oil-rich coal is as follows:

comparing the above three examples, it can be seen that the size fraction and the proportion of the heat carrier in example 1 are more effective for removing the pollutants generated in the coal pyrolysis and the pyrolysis process, so the scheme in example 1 is used.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The solid heat carrier for in-situ pyrolysis of the oil-rich coal is characterized by comprising the following components in parts by mass:

1 part of CaO;

3-4 parts of iron ore;

5-7 parts of blast furnace slag;

wherein, CaO is particles with the particle size of 3-10 mm; the iron ore is particles with the particle size of 2-10 mm; blast furnace slag is a granule having a particle size of 2 to 10 mm.

2. The solid heat carrier for in-situ pyrolysis of oil-rich coal according to claim 1, wherein CaO is particles with a particle size of 5-8 mm.

3. The method for preparing the solid heat carrier for in-situ pyrolysis of oil-rich coal according to claim 1 or 2, which comprises the following steps:

4. A method for carrying out in-situ pyrolysis of oil-rich coal by using any solid heat carrier of claims 1-2.

5. The method for in-situ pyrolysis of oil-rich coal according to claim 4, wherein the solid heat carrier is injected into a horizontal well of a fractured coal seam.