RU2524605C2 - Recovery of solid fuel pyrolysis chemical products - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to chemical industry and metallurgy. Proposed method comprises cooling of solid fuel pyrolysis gases to 25-30°C in primary gas refrigerator (2). Then, gases are cleaned of ammonia, naphthalene and hydrogen sulphide in deep gas cleaning device (4). Green benzene is absorbed at final cooling device (5) to extract hydrogen in unit (12). Resin extracted at carbonisation is treated along with water at stoichiometric ratio of resin:water = 1:1.5. Obtained water-resin emulsion includes sludges and liquid organic wastes. This emulsion is gasified in allothermic gas generator (13) with production of water gas at CO/H₂=1:1 to be enriched with hydrogen extracted at unit (12), at gas mixer (16) to CO/H₂ ratio equal to 1:2-2.5 for production of synthesis gas.

EFFECT: decreased pollution of the environment.

1 dwg

Description

The invention relates to the coal chemical industry and can be used in metallurgy and the chemical industry to create opportunities for the production of a new range of products with high added value at the enterprises of coke chemistry and semi-coking, to reduce the risk of environmental pollution.

It is known that with low-temperature (semi-coking) and high-temperature (coking) pyrolysis of solid fuels, along with solid products (coke, semi-coke), which are in great demand in metallurgy, mechanical engineering, and the chemical industry, significant quantities of high-potential pyrolysis gases, benzene hydrocarbons, resins, and water are formed .

The output of gas, resins and water in various pyrolysis processes is as follows:% wt. from the source of dry raw materials.

Coking: resin water gas 3.0 2,5 fifteen Semi-coking: coal 9,4 3,5 fourteen brown coal 11.0 7.6 fifteen Composition of coking and semi-coking gases Gas enterprises The composition of the gas,% vol. CH ₄ C _m H _n H ₂ With CO ₂ O ₂ N ₂ Q,
kcal / m ³ Coke Chemical 25 2,5 58 6.5 2,5 0.5 four 4000 Coal semi-coking 42.5 2.0 28.5 13.5 10.0 2,5 2,5 5100 Semi-coking
brown coal 20.8 5,0 21.8 21.7 22.1 0.5 8.3 4760

A drawback of existing technologies for the utilization of chemical products of solid fuel pyrolysis is that they are based on traditional methods of fractionation and extraction, which does not allow to separate complex mixtures of several thousand organic compounds into individual products with high added value (S.A. Akhmetov, M. Kh. Ishmiyarov, A. A. Kaufman, Technology for the processing of oil, gas and solid fossil fuels. St. Petersburg: Nedra. 2009. P.581-742, Shkoller M. B. Semicoking of coal and lignite. Novokuznetsk: Engineering Acade Russia Ia -. 2001. - S.164-193).

The highest-boiling compound - pitch, in which, however, there is an increased concentration of carcinogens, is in greatest demand from the products of the resin processing of the coke-chemical enterprise. The remaining wide fractions of the distillation of resins are mainly used as cheap energy carriers. Also, pyrolysis gases enriched in molecular hydrogen are used only as energy carriers.

Very difficult are the problems of treating chemically contaminated waters obtained in the process of coking in an amount comparable to the yield of resin, recycling liquid waste from the chemical unit.

The low demand for chemical products of solid fuel pyrolysis makes it unprofitable to operate the chemical blocks of coal pyrolysis enterprises and coke and semi-coke production technologies with complete combustion of pyrolysis gases directly in the coking or semi-coking reactor enter the market. This does not allow the energy-chemical processing of fuel and receive, in addition to heat, chemical products. Such a path is one of the most impasse in solving the problem of creating non-waste technologies for processing organic fuel.

Therefore, at the same time, work is underway to improve the processing of resins and solid fuel pyrolysis gases

Known patent of the Russian Federation "Method for processing coal tar" No. 2255956, the essence of which is the catalytic hydrogenation of coking resins in a mixture with 10% water in order to obtain raw materials for the production of needle coke. The disadvantage of this method along with the complex multioperability of the proposed technology is that the properties of only the pitch fraction are improved. The rest of the resin is still cheap technical products. In addition, this method is not applicable for the processing of semi-coking resins.

In accordance with application for US patent No. 2002/0052532, NKI 585/275 for the processing of semi-coking resin, it is also necessary to apply multi-operation technologies of catalytic hydrogenation and hydrocracking with subsequent distillation (fractionation), extraction by catalytic reforming.

The closest analogue of the proposed method is the method of disposal of chemical products described in the article P. Dimer, H.Yu. Killich, C. Knopp, H.B. Lyungen, M. Rainke, P. Schmele. // Possibilities for utilization of blast furnace gas at

metallurgical plant. Ferrous metals, December 2004, pp. 10-17, Fig. 7, (p. 13). The disadvantages of this method is that it provides gasification only resin. Experiments show that the gasification of tar, and not emulsions with water, is accompanied by abundant soot formation, which is characterized by an increased content of carcinogenic compounds, in particular benz (a) pyrene. In addition, the method does not provide for the utilization of coking water released during the cooling of coke oven gas and liquid organic waste generated during its deep cleaning.

A universal method for the disposal of chemical products for the pyrolysis of solid fuels is proposed, the task of which is to replace the existing assortment of low-demand chemical products for the pyrolysis of solid fuels with an assortment of chemical products that are in high demand, and reduce environmental pollution.

In a method for the disposal of chemical products of the pyrolysis of solid fuels, including cooling gases to a temperature of 25-30 ° C, the separation and separation of tar, water and fus, gas purification from ammonia, naphthalene and hydrogen sulfide, the capture and processing of crude benzene, the evolution of hydrogen from gases, processing resins, water treatment, utilization of liquid organic waste and fus, the processing of the entire resin is carried out together with water in a stoichiometric ratio of resin: water = 1: 1.5 by preparing a water-tar emulsion, which also includes fus and liquids and gasification of organic waste in the emulsion allothermic gasifier to obtain water gas with a ratio of CO / H ₂ = 1: 1, water gas enriched with hydrogen extracted from the feed gas to a ratio of CO / H ₂ = 1: 2-2.5 for the synthesis of gas.

In accordance with this method, the resin, pyrolysis water and organic waste separated during cooling of pyrolysis gases are used to prepare water-tar emulsions in a stoichiometric ratio of carbon of organic compounds and water = 1: 1.5 mass. These emulsions are gasified in a heated allothermic gas generator to produce water gas of the composition: 50% vol. CO + 50% vol. H ₂ . Molecular hydrogen is released from the pyrolysis gases, part of which is mixed with water gas to produce synthesis gas with a ratio of CO / H ₂ = 2-2.5 vol. The remaining amount of hydrogen is a commercial product of the enterprise. The synthesis gas is sent to the installation of this enterprise for catalytic synthesis using known technology (for example, Fischer-Tropsch, Mobile, Zeosin, etc.) to produce motor fuels (high-octane gasoline, diesel fuel) alcohols and aromatic hydrocarbons. Synthesis gases are used to generate heat and generate electricity, and synthesis water is used to prepare initial tar-water emulsions (see. Fig.).

The main types of solid fuels include coal and lignite. Pyrolysis is the main technological process of their processing and is carried out in two versions - semi-coking (heating to 500-600 ° C) and coking (heating to 900-1000 ° C). one.

Despite the fact that coking resins, as well as semi-coking resins of hard and brown coals, differ significantly and even fundamentally from each other in terms of hydrocarbon composition, they are close to each other in the content of the main element - carbon.

According to experimental data obtained:

Distributions of the basic elements of WMD in semi-coking products

Types of solid fuels Transitioned during semicoking to tar and gas,% to the content of this element in coal C H N O Brown coals 17-22 61-64 68-83 57-86 Coal 18-25 40-65 15-32 48-90

The carbon content is% wt .:

Coal coking resin - 91.0

Coal semi-coking resin - 89.5

Brown coal semi-coking resin - 89.0

The universality of the proposed method lies precisely in the fact that the processing of resins of any hydrocarbon composition is carried out in the process of steam-water gasification of a water-tar emulsion based on the same reaction

C + H ₂ O = CO + H ₂

with the same mass stoichiometric ratio of carbon resin and water (pyrolysis water + process water) in the emulsion = 1,: 1.5.

Since the carbon content in the resins of various fuels are close to each other, the gases of the gasification process also differ slightly and meet the requirements for the composition of the synthesis gas in the ratio of H ₂ / C = 2-2.5 vol.

Experiments were carried out on the gasification of water-tar emulsions based on semi-coking resins of hard and brown coals under the same conditions (temperature 980-1000 ° C, pressure 1 atm).

Example 1 Gasification of a water-tar emulsion based on semi-coking coal tar was carried out. Received gas composition,% vol.

The name of indicators Average temperature, ° C 990 The composition of the dry gas,% vol CO ₂ 3,51 C _n H _m 1.90 O ₂ 0.21 CO 40.80 H ₂ 50.62 CH ₄ 1.34 N ₂ 1,63 H ₂ / CO ratio 1.24 The gas output per 1 kg of resin, nm ³ / kg 3.0 The degree of decomposition of water. couple,% 4,56 Gasification coefficient,% 93.5

Example 2

Gasification of a water-tar emulsion based on brown coal semi-coking resin was carried out. Received gas composition,% vol.

The name of indicators Average temperature, ° С 990 The composition of the dry gas,% CO ₂ 4.18 C _n H _m 1.22 O ₂ 0.95 CO 42.90 H ₂ 47.98 CH ₄ 1.35 N ₂ 1.41 H ₂ / CO ratio 1.12 The gas output per 1 kg of resin, nm ³ / kg 2.6 The degree of decomposition of water vapor,% 5.85 Gasification coefficient,% 87.0

The data obtained indicate that the synthesis gases obtained by the proposed method from water-tar emulsions based on semi-coking resins of brown and bituminous coals, practically insignificantly differ in their composition.

The evolution of hydrogen from the pyrolysis gases of various types of solid fuels for the enrichment of synthesis gases obtained from water-tar emulsions is also carried out according to a single technology.

The pyrolysis gases leaving the solid fuel pyrolysis reactor 20, cooled in gas collector 1 from 600-800 to 80 ° C, enter the primary gas cooler 2. Resin and water condensed in the gas collector enter the mechanized clarifier 3. In the primary gas cooler 2 the gases are cooled to a temperature of 25 ° C and the additional amounts of resin and water that are released also enter the mechanized clarifier 3. The 3 resin, water and fus extracted in the mechanized clarifier enter the respective collectors 6, 7, 8. Water from the collector 7 in necessary quantities is distributed into the gas collector 1 and dispersant 11, which also receives all the resin from the collector 6, the fusibles from the fusee collector 8. Excess water from the collector 7 is sent to the biochemical treatment device 9. From the primary gas cooler 2, the gases are sent to the device 4 deep purification from naphthalene, ammonia, hydrogen sulfide, then to the device 5 for the final cooling of the gas and absorption of crude benzene and then to the device 12 for hydrogen evolution. Hydrogen is accumulated in the gas tank 14. The dehydrated “rich gas” containing more than 40-60% vol. methane, is used for heating solid fuel pyrolysis reactors 20 and heating the allothermic gas generator 13 of a resin-water emulsion with a ring firebox.

Liquid waste isolated on devices 4 and 5 also flows from the collectors 10 to the dispersant 11. The tar emulsion from the dispersant 11 enters the allothermic gas generator 13. In the allothermic gas generator 13 as a result of the interaction of carbon resin and organic waste with water vapor at a temperature of 900-1000 ° C water gas is produced, consisting of: 50% vol. CO + 50% vol. H ₂ (ratio CO / H ₂ = 1: 1), which is accumulated in the gas tank 15. In the gas mixer 16, the water gas is enriched in the hydrogen content by mixing it with part of the hydrogen from the gas tank 14 to the ratio H ₂ : CO = 2-2 5: 1. From the gas mixer 16, the synthesis gas is sent to the device of this enterprise 17 for the catalytic synthesis of motor fuel: high-octane gasoline, diesel fuel, alcohols, aromatic hydrocarbons (Fischer-Tropsch, Mobil, Zeosin synthesis, etc.), which are new highly liquid products of the enterprise. The new products of the enterprise are also more than 60% of the hydrogen accumulated in the gas tank 14, which is processed at the catalytic synthesis unit 17 into motor fuels and other organic substances.

Associated gases for the synthesis of motor fuels will be used to generate electricity in a gas turbine installation (GTU).

Crude benzene absorbed from coke oven gas in the device 5 is separated from the absorbent in the device 18 for the separation of crude benzene, and then separated into pure products in the device for distillation 19 according to traditional technologies.

An example of the effectiveness of the use of the invention

Using the proposed complex will allow to receive annually at the enterprise with a capacity of 3 million tons of coke / year instead of 80 thousand tons of cheap technical oils and 80 thousand tons of pitch the following products:

Gasoline with OCh 90-100-110 thousand tons

Diesel fuel - 10-11 thousand tons

Hydrogen - 500-550 million m ³

High purity benzene - 25-30 thousand tons

Electricity 25-30 MW

The load on the water treatment plant is reduced more than 2.5 times. The problem of disposal of fus and other liquid waste is also eliminated. It has been experimentally shown that when gasifying tar-water emulsions compared to gasification of tar only, the following takes place:

- reduction of the output in gas emissions of NOx (by about 50%), the emission of soot deposits is reduced by about 3-4 times, and benz (a) pyrene by 2-3 times.

- improving the efficiency and resource of the gas generator. During the gasification of the emulsion, part of the droplets reaches the heating surfaces and explodes on them, which helps not only to prevent deposits, but also to clean these surfaces of old soot formations.

All devices and processes are the latest generation devices and are developed for industrial use.

Claims (1)

A method for utilization of chemical products of pyrolysis of solid fuels, including the separation and separation of resin, water and fus, gas purification from ammonia, naphthalene and hydrogen sulfide, the capture and processing of crude benzene, hydrogen evolution from gases, resin processing, water purification, utilization of liquid organic waste and fus , characterized in that the cooling of gases is carried out to a temperature of 25-30 ° C, and the processing of the entire resin is carried out together with water in a stoichiometric ratio of resin: water = 1: 1.5 by preparing a water-tar emulsion and including fus and liquid organic waste, and gasification of this emulsion in an allothermal gas generator to produce water gas with a ratio of CO: H ₂ = 1: 1, enriching the water gas with hydrogen isolated from a deeply purified gas to a ratio of CO: H ₂ = 1: 2-2.5 to produce synthesis gas.