SU918733A1 - Heat-mass exchange method - Google Patents

Description

(54) METHOD OF HEAT AND MASS EXCHANGE

one

The invention relates to mechanical engineering, in particular to methods for intensifying thermal processes in heat exchange equipment used in the chemical, metalworking, food and other industries of industry.

The known method of heat and mass transfer when heating products in fluidized bed electric furnaces, where to increase the efficiency of heating and reduce the oxidation of products into the fluidized bed, a mixture of combustible gas and air is fed with an air flow rate less than unity C.

The disadvantage of this method is that when gas is burned in a layer, combustion products with low thermal conductivity (CO2, CO) are formed, which reduce the efficiency of heating and promote oxidation of products and, moreover, when gas is burned with an air flow rate less than units, significant underburning of the gas is formed, and additional devices are required for its afterburning and the use of the generated heat.

The closest to the proposed method is the heat and mass transfer by fluidizing the bed of granular material along

the entire volume of air and additional local purging of its coolant. At the same time, heat is additionally supplied in radiation in zones of local purge 2. However, the known method is energy-intensive and does not allow for highly efficient processing of products.

It is known that with an increase in the thermal conductivity of the gas interlayer between the surface and the first row of particles in the fluidized bed, the maximum coefficient of heat transfer between the bed and the heated surface increases.

The purpose of the invention is to intensify the process when processing products immersed in a layer of granular material.

The goal is achieved by the fact that the local blowing of the layer is carried out using a gaseous agent supplied in an amount of 5-6% of the amount of air and having a thermal conductivity higher than that of the latter.

Claims (2)

In this case, helium is used as the gaseous agent supplied to the local purge. The drawing shows schematically an installation for carrying out the proposed method. In the housing 1, workpieces 2 are placed, immersed in a layer of granular material 3, brought to a fluidized state by air entering the layer through pipe 4 and the gas distribution grid 5. At the same time, helium is introduced into the boundary zone of the workpieces at a given speed. The experiments were carried out with a layer of sand d 0.65 - 1 mm. As a product, a cylindrical sensor with a diameter of 6 mm and a copper wire with a diameter of 0.1 mm wound on it were used vertically in the center of the fluidized bed. The layer was fluidized with air, and a jet of gels was applied to the surface of the sensor. The greatest intensity of heat and mass transfer was observed up to a flow rate of gels of 8 l / min with a total flow rate of air of 175 l / min. The addition of gels to an air fluidized layer constituting 5–6% of the total air flow rate makes it possible to intensify heat and mass transfer by a factor of 2. 1. The method of heat and mass transfer by fluidizing a layer of granular material throughout the air and additional local blowing it, characterized in that, in order to intensify the process when processing products immersed in a layer of granular material, the local blowing of the layer is carried out using a gaseous agent supplied in the amount of 5-6% of the amount of air and having a thermal conductivity higher than that of the latter. 2. A method according to claim 1, characterized in that helium is used as the gaseous agent supplied to the local purge. Sources of information taken into account during the examination 1. USSR author's certificate No. 183787, cl. C 21 D 1/74, 1964. 2. USSR author's certificate number 602819, cl. F26 17/04, 1976. ./ J 2