Method and Plant for Thermal Conversion of Solid Fuels

Abstract

The invention relates to thermal conversion of solid fuels with a low organic content and can be used in the fuel-processing industry. Conversion of oil shale or high-ash solid fuels comprises flue-gas drying of feedstock, recovering the solid phase as a heat-carrying agent, feedstock pyrolysis in a reactor, separating a gas-vapour mixture from the coke-ash residue in a dust-settling chamber, discharging ash, cooling flue gases, and combustion of the coke-ash residue. An inert material having an ambient temperature is supplied to the outlet of the coke-ash residue ignition chamber. The plant comprises, arranged in series, a reactor, a dust-settling chamber, a flash-process furnace, a heat-carrier cyclone, an ash cyclone, a waste-heat recovery system, an ash-discharge system and a bin for inert material connected to the outlet of the coke-ash residue ignition chamber. The invention allows for a more complete use of the oil shale energy potential and for obtaining ash with a reduced negative effect on the environment, which makes it possible to use the ash for recultivation of quarries resulting from oil shale mining.

Description

RELATED APPLICATIONS[0001]This Application is a Continuation application of International Application PCT / RU2016 / 000793, filed on Nov. 30, 2016, which in turn claims priority to Russian Patent Applications No. RU2015153090, filed Dec. 10, 2015, both of which are incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]The invention relates to thermal conversion of solid fuels with a low organic content, e.g., oil shale, and can be used in the fuel-processing industry at production of a liquid or gaseous fuel, or an alternative fuel to substitute oil.BACKGROUND OF THE INVENTION[0003]There is a known method and a plant for its implementation (Stelmakh G.N., Tyagunov B.N., et al. Electric process plant for conversion of fine-grained oil shale. Oil shale, No. 2 / 2, 1985, pp. 189-196).[0004]The method comprises drying of ground fuel with a gaseous drying agent, pyrolysis of dried fuel with a solid heat-carrying agent with generation of vapour gases and coke-ash resid...

AI Technical Summary

Benefits of technology

The purpose of this patent is to control the temperature in a flash-process furnace and reduce the size and metal consumption of the equipment needed for this process.

Problems solved by technology

The disadvantage of the method lies in that after-burning of flue gases in the recovery boiler at a α<1 results in incomplete oxidation of combustible components contained therein, and hence, to pollution of the environment with products of incomplete combustion of organic fuels.

Pollution of the environment is also contributed to by the fact that, in the course of drying in the flash-process drier, some of the fuel particles are overheated, which results in bertinization products (carbon monoxide, hydrogen sulphide, carcinogenic substances, etc.) coming into the waste drying agent, thus polluting the environment.

The disadvantage of the method lies in that no after-burning is provided for flue gases of the flash-process furnace, which results in pollution of the environment with products of incomplete combustion.

The disadvantage of this method and plant is that to ensure regulating the quantity of the material being fed and the temperature it is necessary to install additional equipment, e.g., a heat exchanger, or a separator, which complicates the arrangement.

Besides, delivering a part of ash at the temperature of 250-600° C. complicates handling the process, as it requires accuracy in feeding a loose material at a constant temperature: feeding a loose material at a temperature below 250° C. may result in termination of the burning process, while limiting the minimum ash temperature to 250° C. would result in larger amounts of the material fed and, as a consequence, a larger volume of the furnace combustion chamber, as well as larger dimensions of equipment for separation of the heat-carrying agent and ash.

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