The aim of this work is to study coal steam gasification with various methods of coal in-core treatment in FB using a newly developed thermodynamic calculation method. A calculational study of subbituminous coal steam non-catalytic gasification was carried out using four different methods of coal in-core treatment in single-vessel multisectional fluidized-bed gasifiers. A semi-empirical model based on the entropy maximization thermodynamic method and “restricted equilibria” based on previously obtained experimental data has been developed. Based on thermodynamic calculations, the effect of the leading thermochemical processes and operating parameters of the fluidized bed (temperature, fluidization number, steam/coal ratio feed rate) was revealed. New information was obtained regarding the composition of char and syngas at the gasifier outlet, the syngas heating value, and the cold gas efficiency of the steam gasification of Borodinskiy subbituminous coal char. The results indicate the possibility of significantly accelerating and improving non-catalytic steam gasification in fluidized bed gasifiers through the appropriate organization of in-core coal treatment. Based on the results obtained, the following recommendation is made—when designing multi-section and multi-vessel steam-blown gasifiers, the ratio of residence times should be set in favor of increasing the coal residence time in the steam-blown carbonization zone. Structurally, this can be achieved by increasing the volume and/or area of the steam-blown carbonization section (vessel).

During the bed gasification of solid fuels, the process temperature in the reaction zone is not high enough for reaching the maximum rate of the chemical efficiency factor of the gasification process. In order to increase the chemical efficiency factor, it is necessary to supply extra heat to the reaction zone to increase the reaction temperature. In this article, coal gasification in a chamber with forced fluidized bed is considered and it is proposed to supply extra heat with a circulating flow of an inert particulate heat transfer agent. Circulating inert particulate material is successively heated by coal combustion in a cone chamber with bubbling fluidized bed and in a combustion chamber with a spherical nozzle that inhibits the forced fluidized bed. After that, the heat transfer agent heated to 930–950°C enters first in a gasification chamber with bubbling bed and then in a chamber with forced fluidized bed, where it transfers the physical heat to the air fuel mixture. The experiments conducted with crushed Borodinsky coal and inert particulate heat transfer agent (electrocorundum) showed the temperature rise in a gasification chamber with from 760 to 870°C and the increase in the combustible component (CO) concentration in the gasification products by 5.5%. Based on the kinetic equations of the fuel combustion reactions and the CO₂ reduction to CO and on the thermal balance equations of combustion and gasification chambers, the simulation model for the gas composition and the temperature rate calculated by the height of reaction chambers was developed. The experimental temperature rates and product gas compositions are in good agreement with the simulation results based on the proposed kinetic gasification model.

Conical diffusers are widely used in technical devices (gasifiers, turbines, combustion chambers) and technological processes (ejectors, mixers, renewable energy). The perfection of flow gas dynamics in a conical diffuser affects the intensity of heat and mass transfer processes, the quality of mixing/separation of working media and the flow characteristics of technical devices. These parameters largely determine the efficiency and productivity of the final product. This article presents an analysis of experimental data on the gas-dynamic characteristics of stationary air flows in a vertical, conical, flat diffuser under different initial boundary conditions. An experimental setup was created, measuring instruments were selected, and an automated data collection system was developed. Basic data on the gas dynamics of air flows were obtained using the thermal anemometry method. Experimental data on instantaneous values of air flow velocity in a diffuser for initial velocities from 0.4 m/s to 2.22 m/s are presented. These data were the basis for calculating and obtaining velocity fields and turbulence intensity fields of the air flow in a vertical diffuser. It is shown that the value of the initial flow velocity at the diffuser inlet has a significant effect on the gas-dynamic characteristics. In addition, a spectral analysis of the change in air flow velocity both by height and along the diffuser axis was performed. The obtained data may be useful for refining engineering calculations, verifying mathematical models, searching for technical solutions and deepening knowledge about the features of gas dynamics of air flows in vertical diffusers.

Термохимический реактор восстановительных атмосфер с окислением части продуктов паровой конверсии метана

Syngas for the battery of solid oxide fuel cells is produced in a gas generator with a fluidized layer consisting of a mixture of electrocorundum and semi-coke of the Borodino coal at the temperature of 850 °C, fluidizable by steam in a retort heated from the outside. The concentration of semi-coke is 627 kg per 1m³ of mixture of electrocorundum and semi-coke. The heat of combustion of the obtained syngas is 13359 kJ/kg. Syngas is purified in a cyclone – dust collector and gas purification from SO₂ and H₂O.