WO2018124926A1

WO2018124926A1 - Method for heat treating light fractions of high-ash fuels, including oil shales and brown coal

Info

Publication number: WO2018124926A1
Application number: PCT/RU2017/000317
Authority: WO
Inventors: Игорь Евгеньевич БИДИЛО
Original assignee: Акционерное Общество "Атэк Групп"
Priority date: 2016-12-30
Filing date: 2017-05-17
Publication date: 2018-07-05

Abstract

A method for treating light fractions of high-ash fuels, including oil shales and brown coal, involves pyrolising an organic portion of a high-ash solid fuel and separating it into a coke-ash residue and a vapour-gas mixture. What is novel is that a rotary thin film evaporator is used to remove ash from a circulating heavy oil in a system for condensing the vapour-gas mixture, and the resultant high-ash oil is brought directly into a reactor for secondary pyrolysis. This makes it possible to produce a marketable product that has a low ash impurity content (less than 0.02%) without the additional expenditures associated with the provision of filtration and residue disposal, and to increase the yield of shale oil light fractions and extract ash by standard procedure.

Description

METHOD FOR THERMAL PROCESSING OF LIGHT FRACTIONS OF HIGH-ASH FUELS, INCLUDING FUELS

SHALE AND LOCAL COAL

The invention relates to the field of thermal processing of oil shale and can be used in the fuel processing industry in the production of liquid or gaseous fuels or oil substitutes.

A known method of processing oil shale, including heating fine-grained shale with a solid heat carrier to form a vapor-gas mixture, which after dry cleaning of mechanical impurities is cooled by irrigation with the recirculating part of the heavy resin released during cooling of the vapor-gas mixture, the removal of non-condensed vapors with their subsequent separation into medium, light and gasoline fractions of tar (oil), tar pitch and semi-coking gas (see Chemistry and technology of shale tar, edited by N.I. Zelenin. L., published by Chemistry, 196 8, p. 77-78).

The disadvantage of this method is that the resulting heavy resin fraction (oil) contains an increased amount of mechanical impurities. Such oil cannot be used as fuel or chemical raw materials without preliminary treatment.

A known method of processing fine-grained coal in plants with a solid heat carrier, developed by the State Research Institute of Energy named after Krzhizhanovsky G.M., which received the name "Haloter". In this method, as a coolant is used the coke-ash residue formed after the pyrolysis process and burned in an aerial fountain. The process is implemented in industry at the UTT-500 and UTT-3000 plants, where 500 and 3000 mean the amount of processed oil shale in tons per day. The processing of oil shale in these plants is carried out in a rotating drum reactor, which receives a mixture of fine oil shale dried in an air fountain dryer and coolant from an air fountain furnace through a mixer in front of the reactor. Products formed: the coke-ash residue is discharged through a separator system for utilization, the flue gases are discharged through an air fountain dryer, where part of the heat is transferred to dry shale and, after further purification, is discharged into the atmosphere.

This method is the basis of the invention, which is closest to the claimed method. A method for the thermal processing of oil shale, comprising heating fine-grained oil shale with a solid heat carrier to form a gas-vapor mixture. Irrigation of a steam-gas mixture with a mixture of condensates of heavy and light tar and its cooling with the release of condensate of a heavy tar, partially returned for irrigation, condensation combined with rectification of the non-condensed part of the gas-vapor mixture with the release of light and medium tar, separation of gasoline, mixing of the condensate of heavy tar with gasoline, cleaning with sludge the resulting mixture and fus, return of the purified mixture to rectification (see RF patent JV ° 1663011, IPC С10В53 / 06, publ. 15.07.91).

The disadvantage of this method is that in the circulating stream of heavy resin ash accumulates and continuously withdraw it for further cleaning. At the same time, it is necessary to return a part without an ash product to maintain a minimum concentration of dust in the circulating oil (not more than 10%) and reduce viscosity.

The task of the invention is to obtain a product with a low content of ash impurities without additional costs for the organization of filtration and disposal of residues.

To solve this problem, the proposed method for processing high-ash solid fuels, including pyrolysis of the organic part of high-ash solid fuels and separating it into a coke-ash residue and a gas-vapor mixture, uses a rotary-film evaporator to clean the heavy circulating oil from the ashes in the vapor-gas mixture condensation system, and the resulting high-ash oil is sent for secondary pyrolysis directly to the reactor.

This allows you to get a marketable product with a low content of ash impurities (less than 0.02%) without additional costs for organizing filtration and disposal of residues, increase the yield of light fractions of shale oils and remove ash according to the standard scheme.

In FIG. 1 of the accompanying drawings shows an installation diagram for implementing the method.

The method is as follows.

Shale or other high-ash fuel, after crushing to a fraction of O-20 mm. is fed by a screw feeder to dryer 1, where it is dried as a result of contact with exhaust flue gases. The air suspension of dry shale and flue gas is separated into cyclone 2 and fed by a screw feeder to mixer 3, where it is mixed with a coolant and sent to a rotating reactor 4. High ash oil (up to 30% ash) is fed directly to the reactor inlet from the bottom of the rotor film evaporator. In the reactor at a temperature of 450-550 C, thermal decomposition (pyrolysis) of the organic part of high-ash fuel occurs. From the reactor, the reaction products enter the dust collection chamber 5, equipped with cyclones, where they are separated into a coke-ash residue and a gas-vapor mixture.

The coke-ash residue from the lower part of the dust collecting chamber is fed by a screw feeder into the aero-fountain furnace 6. Air is supplied to the lower part of the aero-fountain furnace. The semicoke is combusted at a temperature of 750-950 C.

The air suspension of ash and flue gases enters the heat carrier cyclone 7, where part of the ash is taken out, and is sent to the mixer 3 as the heat carrier. The remaining air suspension enters the ash cyclone 8. The ash from the cyclone enters the ash heat exchanger 9, where it is cooled to generate steam and removed from the process for disposal. Flue gases from the cyclone 8 through the waste heat boiler 10 enter the dryer 1, then through the cyclone 2 into the flue gas treatment system 11 (i.e. cyclones, filters) and are discharged into the atmosphere.

The gas-vapor mixture through cyclones of the dust precipitation chamber enters the scrubber 12. The scrubber 12 is irrigated with heavy circulating pyrolysis oil, as a result of which the vapor-gas mixture is rapidly cooled from 450-550 С to 200-300 С and it is washed from particles carried away from the dust precipitation chamber, ash. Of Scrubber 12 contaminated circulating oil is fed into the tank 13, whereupon the pump 15 again goes through the refrigerator 14 to the scrubber 12. The rest of the gas-vapor mixture from the tank 13 is fed to further condensation and the separation system to the desired fractions. Part of the flow of circulating oil from the tank is directed to the rotary-film apparatus 16. The amount of flow is selected so as to remove the fly ash from the system and prevent its accumulation. The refined oil is returned to the tank 13, the excess is removed as a commercial product. The high-ash residue from the cube of the rotary film evaporator is fed directly to the reactor 4, where it is processed into light fractions. Ash from the high ash residue is disposed of according to the standard scheme.

Claims

CLAIM

A method of processing light fractions of high-ash fuels, including oil shale and brown coal, including the pyrolysis of the organic part of high-ash solid fuel and its separation into a coke-ash residue and a gas mixture, characterized in that for cleaning heavy circulating oil from ashes in a vapor-gas condensation system the mixtures use a rotary film evaporator, and the resulting high-ash oil is sent for secondary pyrolysis directly to the reactor.