SU948206A1 - Method for drying disperse materials - Google Patents

Abstract

THE METHOD OF DRYING DISPERSE MATERIALS by feeding them into the upper part of the fluidized bed of the nozzle, which has the FLOW rate of fluidization above the soak rate of the particles is dried-. material, characterized in that, in order to intensify the drying process, a catalyst for continuous oxidation of the fuel, heated by burning the fuel in the lower part of the catalyst bed, is used as a nozzle.

Description

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The invention relates to processes for drying powdered materials in a fluidized bed of a dispersion nozzle and. Can be used in Chemical, Metallurgical, Coal and other industries. . -. .

The known method of drying solutions and suspensions, which is carried out in a fluidized bed of a dispersed nozzle 1,.

There is also known a method of drying wet powder materials in a fluidized bed of an inert packing by feeding them to the upper part of layer 2),

A characteristic feature of this method is that the drying of powdered materials occurs upon contact in the upper zone with nozzle particles that are in a fluidized state and have one. the fluidization rate is higher than the soar speed of the particles of the material being dried. Heating of the nozzles in such processes is carried out by high-temperature flue gases in remote chambers or directly in the working volume of the fluidized bed. ..

The disadvantage of this method is that the heating intensity of the nozzle is limited by convective heat transfer from hot flue gases and is determined by the temperature difference between the gas and the nozzle under operating conditions. The use of very high flue gas temperatures for heating heat (on the order of 1000 ° C) is fraught with difficulties, such as increasing the requirements for thermochemical properties of structural materials, local overheating of the material being dried. Dilution of flue gases to moderate temperatures (ZOO-TOO with) leads to a decrease in the intensity of the drying process, reducing the performance of the device. Heating nozzles in remote chambers in a non-convective way is associated with high energy costs and is not economically viable.

The aim of the invention is to increase the intensity of the drying process, increase the thermal performance of a unit of working volume, reduce heat loss with flue gases.

The essence of the proposed method lies in the fact that instead of the inert dispersed nozzle, a ball catalyst is used to completely oxidize the fuel, and the catalyst is heated by burning the fuel in a stoichiometric ratio: SRI with air on its surface in the lower part of the fluidized bed. At the same time, 20% of the heat released is

for heating the vacuum cleaner agent, the remaining amount of heat is accumulated by the catalyst granules. High speed yukislenn fuel. the presence of a catalyst makes it possible to increase the energy intensity of a unit of a working volume under all other equal conditions by approximately five times as compared with known methods of drying powdered materials in a fluidized bed of packing.

Thus, the proposed method allows combining the processes of heating the latter by combusting the fuel in air at a stoichiometric ratio with air and transferring heat to the material being dried, significantly increasing heat stress in one fluidized bed of a ball catalyst. working volume and thereby reduce the size and material consumption of devices. In addition, the proposed method allows to reduce the temperature level of the fuel combustion process, eliminate the emissions of toxic products of high-temperature combustion, increase the heat utilization rate by reducing the amount of flue gases. Separation. zones of fuel combustion and heat removal, during material drying along the height of the fluidized bed, reduce the material drying temperature to the minimum necessary limit and reduce heat loss with bypassing smoke gases.

Example 1. A steel reactor with an internal diameter of 250 mm, equipped with a gas distribution grid with a living cross section of 5%, loads 25 kg of EO full oxidation catalyst copper chromium {balls size 2-2.5 mm, bulk density 1000 kg / m3). The rate of onset of fluidization by flue gas and for this catalyst is 0.9 m / s.

From below, the catalyst bed preheated to 250 ° C is supplied with a stoichiometric ratio (ot 1.0-1.1) air and fuel. The air flow rate is set so as to bring the catcher into a fluidized state, and is equal to 120. The linear speed of the fluidizing agent in the cross section of the device is 2.22, 8 m / s. In the lower part of the fluidized bed of catalyst, intense heat is generated due to the catalytic oxidation of the fuel. The temperature here is maintained right.

A dried material (porous aluminosilicate adsorbent) with an initial moisture content of 17 wt. % in quantity. 1000 kg / h. Fractional composition of the dried adsorbent is less than 0.4 lm. The winding speed of such adsorbent grains is 1.2 m / s.

Intensive removal of heat in the upper zone of the fluidized bed occurs in. J score of water from the surface of the particle in direct contact with the catalyst grains. Realized operating conditions allow the material to be dried at 11013 ° C to a final moisture content of 34 wt. % ..

More than 80% of the heat generated during the compression of fuel is consumed in the process of drying the wet material.

A: EXAMPLE 2. It is performed analogously to Example 1, only in. As the material to be dried, an adsorbent with an initial moisture content of 35% by weight and the same fraction of HbJM composition, injected in an amount of 600 kg / h, is used. .

Drying is carried out at. 120-150 With to final humidity of 4-5 weight%.

At the same time, about 90% of the heat released during the combustion of the fuel is transferred to the material being dried.

The proposed method of drying powdered materials in the fluidized bed of a ball catalyst for complete oxidation of the fuel allows drying in a decade of a second at relatively low temperatures due to direct contact. material and hot catalyst grains. . This makes it possible to significantly increase the productivity of a unit volume of the fluidized bed by drying our material and reducing heat losses with the exhaust gas.

Claims (1)

METHOD OF DRYING DISPERSED MATERIALS by feeding them to the upper part of a fluidized bed of a nozzle, · having a fluidization rate higher than the speed of the particles of the dried material, characterized in that, in order to intensify the drying process, a catalyst for the complete oxidation of fuel heated by burning fuel in bottom of the catalyst bed. "and 00 KE F F