RU2413749C2 - Procedure for complex coal processing and installation for its implementation - Google Patents

Abstract

FIELD: gas-and-oil producing industry.

SUBSTANCE: present invention refers to coal processing and is designed for production of synthetic liquid fuel and burning gases. Here is disclosed the procedure for complex processing coal for production of liquid fuel and burning gases. The procedure consists in preparation of oil-coal suspension out of dust-like coal and heavy oil, in suspension semi-coking in a reactor under pressure of 2-5 MPa and interval of temperature 500-680°C, in utilisation of water steam super-heated to 800-900°C as heat carrier, in preparation of semi-coke from steam-gas mixture, in cooling and dividing steam-gas mixture into benzene, gas-oil fractions and heavy oil, in steam-oxygen gasification of produced semi-coke and heavy oil, in production of synthesis gas and in synthesis gas cooling and treating. There is also disclosed the installation for production of liquid fuel and burning gases from coal as per claim 1. The installation consists of a device for suspension preparing connected to the reactor of semi-coking. A steam super-heater is connected to the reactor. Also, the reactor of semi-coking is coupled with a separator, one output of which is connected with a serially arranged contact heat exchanger, oil scrubber and rectifying column, while the second output is coupled with a gasifier communicated with a boiler-utiliser joined to a water scrubber with a sump. The sump is connected with an absorber of sulphuric compounds and further - with a stripper. Also, steam-gas mixture primary cooling is made with heavy oil in the contact heat exchanger. Another part of oil is directed to the device for suspension preparing. Balance amount is directed to the gasifier.

EFFECT: simultaneous production of synthetic fuel and gases of medium calorie out of coal without contact of intermediate products with atmospheric air; reduced production expenditures and minimisation of harmful substances exhaust into environment.

2 cl, 1 dwg

Description

The invention relates to a fuel and energy complex, and more particularly, to the production of synthetic liquid fuels (SLC) and combustible gases from coal and brown coal.

The main methods of processing fossil and lignite are thermal degradation, hydrogenation, thermal liquefaction, gasification with oxidizing agents. All these methods are energy-intensive and are not widely used in comparison with oil refining. According to forecasts, the decline in oil prices in 2009 will not be long-term. And currently, many countries are exploring methods for processing solid fuels into liquid fuel and combustible gases. Already operating plants for the production of liquid fuel and high-calorie gases prove the economic feasibility of these industries. But the cost of producing liquid fuel and gas from coal remains high. In addition, there is a significant release of harmful substances into the environment.

There are various methods of semi-coking and gasification of coal [1, 2]. Close to the invention is the process of semi-coking with internal heating of the coal layer by gas coolants, which are the products of gas combustion with a large excess of air. These gases, having a temperature of 600-750 ° C, penetrate the coal layer and heat it to a temperature of 460-620 ° C, at which semi-coking occurs. The heating gases are mixed with the gaseous products of coking and removed from the reactor. In this way a low-calorie gas is obtained (Q _n = 5800-8800 kJ / m ³ ) containing resins, phenols and other liquid hydrocarbons. Resins are usually released from it, and gas is used for own needs without purification. Therefore, the process of semicoking with a gas coolant is ineffective and environmentally dirty and is currently almost never used [1].

Known methods for semi-coking (thermal pyrolysis) of pulverized coal when heated by gas and solid heat carriers in flow reactors [2]. Liquid products (pyrolysis resin) are fractionated and then subjected to hydrogenation processing to produce motor fuels. But due to the large production costs, these methods have not found industrial application.

Known methods for one- and two-stage gasification of solid fuels with oxidizing agents (O ₂ , H ₂ O), in which coal is first pyrolyzed to produce coke or semi-coke (depending on conditions), and then vapor-oxygen gasification of the solid residue. In all these processes, gas is obtained with an average calorific value (12000-17000 kJ / m ³ ). SLC in these ways do not get [1, 3].

Analogs of the invention are the processes of "Synthan" of the American Mining Bureau and "Bi-gas" of the company "Bitominoles Cole Research" [4, 5].

The target product of these processes is a mixture of semi-coking coal gases and vapor-oxygen conversion of semi-coke. The reactor (gasifier) consists of two sections with a fluidized bed. Fine-grained coal is fed into the upper zone of the gasifier, where converted gas, which serves as a coolant, flows from below. The resulting semi-coke is poured into the lower section, where it is gasified with a vapor-oxygen mixture. These processes have significant disadvantages. In the semi-coking zone, a gas is formed containing resins, phenols, and heavy hydrocarbons. Therefore, a deep gas purification is necessary, but the content of by-products is insignificant, and they are often not used, worsening the environmental situation.

Fluidized bed reactors are characterized by complete mixing of all the ingredients, and the coke residue left from the bottom of the gasifier contains a significant amount of coke. Therefore, the carbon utilization coefficient does not exceed 90%, and the energy efficiency is about 70%. The purpose of the Bi-gas and Synthan processes is to produce only flammable gases, and the semi-coke gasification gases are the heat carrier for the semi-coking process. Therefore, none of them can be considered a prototype of the presented invention, the main purpose of which is to obtain synthetic liquid fuels and combustible gases. Closer analogues are unknown.

The aim of the invention is the joint production of synthetic liquid fuels (gasoline and gas oil fractions) and medium calorific gases from coal without contact of intermediate products with atmospheric air. This leads to lower production costs for the production of secondary fuels and minimal emissions of harmful substances into the environment. This goal is achieved by two-stage coal processing. At the first stage, semi-coking of coal is carried out to produce SLC and semi-coke, and at the second stage, vapor-oxygen gasification of the obtained semi-coke.

The claimed method is as follows. At the first stage, semi-coking of coal is carried out using superheated water vapor as a heat carrier. The gaseous products of pyrolysis together with steam are diverted to cooling and separation. The separated semi-coke, together with the ash, enters the second stage of processing by means of vapor-oxygen gasification. In this case, synthesis gas (H ₂ , CO, CO ₂ , H ₂ S) and an ash residue are formed, which is removed from the bottom of the reactor. As a result, the target products of the combined coal processing method are: semi-coking gas, gasoline fraction, gas oil fraction and synthesis gas. By changing process parameters, the yield of these products can be varied. The joint receipt of these products and the fuller use of their physical heat (enthalpy) leads to a significant reduction in specific capital investments and production costs.

The method of complex processing of coal includes the following processes: preparation of raw materials for semi-coking - an oil-coal suspension from pulverized coal and heavy oil; semi-coking (thermal pyrolysis) of the suspension in the reactor under a pressure of 2-5 MPa and a temperature range of 500-680 ° C using water vapor superheated to 800-900 ° C as a heat carrier; separation of semi-coke from a gas-vapor mixture; cooling and separation of the vapor-gas mixture into gasoline and gas oil fractions and heavy oil; vapor-oxygen gasification of the obtained semi-coke and heavy oil to produce synthesis gas; cooling and purification of synthesis gas.

According to the claimed method can be processed "fat" stone and all brown coal with any ash and moisture content. But with greater efficiency, enriched coal is processed with an ash content of not more than 10 and a moisture content of not more than 5%.

Pulverized coal with particle sizes up to 0.1 mm is mixed with heavy oil of its own production and the resulting suspension (pulp) is fed to a semi-coking reactor using a special high-pressure pump, where superheated water vapor with a temperature of 800-900 ° С is also supplied. The pressure in the reactor is 2-5 MPa. Raw materials are mixed with steam and depending on the ratio of steam: raw materials and steam temperature, the temperature of the mixture will be at the level of 620-680 ° C. At this temperature, thermal pyrolysis of coal and heavy oil occurs in the dust and gas stream. As a result of oil pyrolysis, the yield of lighter products (mainly gasoline and gas oil fractions) increases. The total pyrolysis reaction is endothermic, with a slight thermal effect, and the temperature of the reacting mixture decreases to 500-570 ° C. When semi-coking “fat” coals with an output of volatiles of 35-40% and brown coals with an exit of volatiles of 45-55% to the organic mass of coal and with respect to coal: heavy oil 1: 1, the approximate yield of products is obtained (kg per 1 t organic mass of coal):

fossil fuels brown coals Semi-coking gas (C ₁ -C ₄ , CO, CO ₂ ) 70-100 60-100 Gasoline fraction (<220 ° C) 30-60 30-50 Gas oil fraction (220-350 ° С) 60-80 50-70 Heavy oil (> 350 ° C) 60-90 70-100 Semi-coke 600-700 600-650 Pyrolytic water 30-50 50-80

After separation of the semi-coke, the gas-vapor mixture is cooled to a temperature of 350-400 ° C in a mixing refrigerator and an oil scrubber and fed to a distillation column, where it is separated into a gas-vapor fraction (C ₁ -C ₄ , Н ₂ О), gas oil and heavy oil. The top product of the column is cooled to 30-40 ° C, partially condensed and then separated into gas, water condensate and gasoline. The necessary amount of heavy oil is fed to the preparation of the suspension, the rest to gasification.

The semi-coke and heavy oil obtained by semi-coking are gasified to produce synthesis gas (artificial gas) - an environmentally friendly fuel or raw material for organic synthesis. Used vapor-oxygen gasification in the stream. Gasification of 1 ton of coal requires approximately 360 kg of oxygen and 400 kg of water vapor. The pressure in the gasifier is slightly lower than in the semi-coking reactor and amounts to 1.9-4.8 MPa, the maximum temperature in the reaction zone is 1350-1400 ° C, and at the outlet it is about 1200-1300 ° C, and the reaction products are only H ₂ , СО, СО ₂ , Н ₂ S with a slight admixture of other gases. The synthesis gas is cooled in a recovery boiler with steam generation and in a water scrubber, and then it is purified from sulfur compounds by known methods. Thus, the products of complex coal processing are synthetic liquid fuels - gasoline and gas oil fractions and combustible gases. For the above coals, the yield of products will be approximately (kg per 1 ton of organic mass of coal):

fossil fuels brown coals Synthesis gas 1650 1530 Hydrocarbon gas one hundred 90 Gasoline fraction 60 40 Gas oil fraction 70 60

The claimed method of processing coal is carried out on a technological installation, which has a significant novelty. Schematic diagram of the technological installation is shown in the drawing. The installation comprises an apparatus for producing an oil-coal suspension (pulp) 1, a pump for suspension 2, a semi-coking reactor 3, cyclone separators 4 and 10, a superheater 5, a mixing cooler 6, an oil scrubber 7, a distillation column 8, a three-phase separator 9, a gasifier 11 , recovery boiler 12, water scrubber 13, sump 14, absorber 15, stripper 16.

Pulverized coal with particle sizes up to 0.1 mm is fed to the apparatus for preparing an oil-coal suspension 1. A suspension with a coal: oil ratio of (1.2-0.8): 1 is obtained at atmospheric pressure and a temperature of 150-300 ° C with intense mechanical or cavitation mixing. In this case, partial dissolution of coal in oil occurs.

The apparatus for preparing the suspension 1 through the pump 2 is connected to the semicoking reactor 3, the pressure in which is in the range of 2-5 MPa. The reactor is also connected to a superheater 5, in which water vapor is superheated under a pressure of 3-6 MPa to a temperature of 800-900 ° C. The vapor atomizes the oil-coal suspension, and the dispersed mixture moves down and the mixture is pyrolyzed. The bottom of the reactor is connected to a cyclone separator 4, which is connected via a gas-vapor phase to a mixing cooler 6, into which cooled heavy oil is supplied. The outlet of the refrigerator is connected to an oil scrubber 7, into which a vapor-liquid mixture with a temperature of 300-400 ° C enters. The scrubber is connected to a distillation column 8, the top of which is connected to a three-phase separator 9, from which semi-coking gas is discharged, and the liquid is stratified into gasoline and water condensate. The gas oil fraction is discharged from the middle, and heavy oil from the bottom of the column 8.

Pipelines of heavy oil and pulverized coke from separators 4 and 10 are combined into one pipeline, which is connected to a waste heat boiler 12. The common pipeline is connected to a gasifier 11. Oxygen is supplied to the gasifier and gas-vapor gasification of the raw material mixture takes place. The gasifier in the gas phase is connected to the recovery boiler, in which the synthesis gas is cooled to 300-400 ° C. The recovery boiler is connected to a water scrubber 13 with a settling tank 14. The scrubber is connected to an absorber of sulfur compounds 15, which is connected to an absorber to an absorber 16. The synthesis gas purified from sulfur compounds is removed from the absorber, and a gas containing H ₂ S an admixture of COS, CO ₂ and other gases, which is sent to the installation for the production of sulfur or sulfuric acid.

The sump 14 is connected to the gasifier 11, and part of the water from it is used to extinguish the slag, and the rest of the water is directed to the treatment plant.

LIST OF LINKS

1. Chemicals from coal / under. ed. Y. Falbe. - M .: Chemistry, 1980 .-- 516 p.

2. Chukhanov Z.F. Some problems of fuel and energy. M .: Publishing. ANSSSR, 1961 .-- 478 p.

3. Directory nitrogen. 2nd ed. - M .: Chemistry, 1986. - 512 p.

4. Corder W.C., Batschelder H.R. 5th Synthetic pipeline Gas Simposium, Chicago, 1973.

5. Grace R.J. et al. Design of Bi-gas Pilot plant. 5th Synthetic pipeline Gas Simposium, Chicago, 1973.

Claims (2)

1. A method for the integrated processing of coal to produce liquid fuels and combustible gases, comprising preparing an oil-coal suspension from pulverized coal and heavy oil; semi-coking of the suspension in the reactor under a pressure of 2-5 MPa and a temperature range of 500-680 ° C using water vapor superheated to 800-900 ° C as a heat carrier; separation of semi-coke from a gas-vapor mixture; cooling and separation of the vapor-gas mixture into gasoline and gas oil fractions and heavy oil; vapor-oxygen gasification of the obtained semi-coke and heavy oil to produce synthesis gas; cooling and purification of synthesis gas. 2. Installation for producing liquid fuels and combustible gases from coal according to claim 1, consisting of a slurry preparation apparatus connected to a semi-coking reactor to which a superheater is connected, and the semi-coking reactor is connected to a separator, one output of which is connected to a contact heat exchanger installed in series, an oil scrubber and a distillation column, and the second with a gasifier connected to a recovery boiler connected to a water scrubber with a settler that is connected to the chimney absorber true compounds, and then with a stripper, the primary cooling of the vapor-gas mixture being made with heavy oil in a contact heat exchanger, the other part of the oil is sent to the slurry preparation apparatus, and the balance amount is sent to the gasifier.

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