RU2365838C1 - Method of controlling drying in drum type drying installations - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention is intended for organisation of drying process and can be applied in chemical industry, production of construction materials, food products. In method of controlling process of drying in drum type driers with heating of dried material by gaseous heat-carrier, which has temperature higher than set temperature of died material, range of influence on final humidity of dried material is limited. In case of local overheating of moving in drum material it turns out impossible to reduce its temperature in zone of overheating to permissible as temperature of heat-carrier must be higher than temperature of material. Set task is solved by feeding into zone adjacent to zone of drum discharge of cooling agent flow with temperature lower than set temperature of dried material, supply of heating gas into zone of cooling agent introduction being reduced to minimally permissible. Supply of cooling agent is stopped, if temperature of dried material stabilises on set value or lower one.

EFFECT: achieved are extension of range of controlling influence and increase of drying quality.

Description

The invention is intended to automate the drying process and can be used in the chemical industry, the production of building materials, food products.

Closest to the proposed invention is a method of controlling the drying process in drum dryers with heating of the dried material with a gaseous coolant having a temperature above a predetermined temperature of the dried material (RF patent No. 2287752, F26B 25/22, 03/28/2005, published on November 20, 2006 - prototype) .

According to this method, the supply of fuel and, consequently, the coolant is increased with increasing amount of moisture supplied with the dried material, and reduced with its decrease, so that the moisture content of the dried material remains within acceptable limits.

But the range of impact on the final humidity of the dried material in this method is limited. With local overheating of the material advancing in the drum, it is impossible to reduce its temperature in the overheating zone to an acceptable level, since the temperature of the coolant must be higher than the temperature of the material.

The objective of the invention is to improve the quality of the drying process control. The problem is solved in that in the method for controlling drying in drum-type drying installations with heating of the dried material with a gaseous heat carrier having a temperature above a predetermined temperature of the dried material, according to the invention, when the dried material is overheated locally, a flow of refrigerant is introduced into the zone adjacent to the drum discharge zone temperature below the set temperature of the dried material, and the flow of gaseous coolant in the refrigerant inlet zone is reduced to a minimum incentive.

An example implementation of the invention is shown in the drawing. Material A enters the mixer-granulator 1, where, mixed with water D, it is dried in the first zone of the drum heating chamber 6. The flow rate of water supplied to the mixing with the material in the mixer-granulator 1 is measured by a flowmeter 2. To obtain a coolant flow natural gas. The consumption of natural gas E in the first zone of the heating chamber is measured by a flow meter 3. The flow values are supplied to the control device 4, where the control signal acting on the fuel supply valve to the first zone of the heating chamber 5 is calculated taking into account the delay. The temperature of the gases sucked from the heating chamber is measured thermocouple 7, the signal from which is supplied to the control device 8, command signals from which are supplied to the valve 9, which changes the flow of natural gas 3 into the second zone of the heating chamber of the drum 10 and the damper at 11 cold air supply B - refrigerant.

The air flow rates G and I for combustion of fuel in the first and second zones of the heating chamber are kept in a predetermined ratio to the flow rates of natural gas supplied to these zones, respectively. In the first zone, the natural gas flow rate is measured by the flow meter 3, and the air flow rate G is measured by the flow meter 14. Both signals are fed to the ratio controller 13, the control signal from which acts on the air supply flap 12. In the second zone, the natural gas flow rate is measured by the flow meter 18, and the air flow rate And - flow meter 15. Both signals are fed to the ratio regulator 16, the control signal from which acts on the air supply flap 17.

The spent coolant B is sent by the fans for cleaning. Dried material G is sent to the finished goods warehouse.

Example. Granules of carbon black with an initial humidity of 50% are fed into the installation, the granules are dried to a final humidity of 0.5%. The temperature of the coolant before entering the inner cavity of the drum is 800 ° C. The fuel supply valve is open at a minimum opening value of 30%, the cold air damper is 90% closed.

Claims (1)

A method of controlling drying in drum-type drying installations with heating of the dried material with a gaseous coolant having a temperature above a predetermined temperature of the dried material, characterized in that when the overheated material is locally overheated, a flow of refrigerant is introduced at a temperature below a predetermined temperature of the dried material material, and the supply of gaseous coolant in the zone of introduction of the refrigerant is reduced to the minimum allowable.

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