SU1759920A1 - Method of operating conveyor machines for roasting pellets - Google Patents

Abstract

SUBSTANCE: method includes heating a layer of pellets and roasting carts with a gradual increase in carriage temperature to 650-850 ° C and subsequent cooling of carts with pellets. The cooling is carried out in two stages: in the first stage, the carts are cooled for 2-4.5 minutes with a stream of gases heated to 300-400 ° C, coming from the last vacuum chambers of the cooling zone, and in the second stage, the carts are finally cooled pellets atmospheric air. 1 il.

Description

The invention relates to the preparation of iron ore in ferrous metallurgy, namely the production of iron ore pellets.

Known methods of operating conveyor machines for calcining pellets include heating a layer of pellets and calcining carts with a gradual increase in temperature and cooling carts with pellets using atmospheric air as a cooling agent.

The disadvantages of these methods are the supply of cold air to the hot metal of the kiln carts, which, due to the sharp heat exchange conditions, causes an accelerated equipment failure, a low degree of heat recovery of the waste gases from the cooling zone.

As a prototype, a method of operating conveyor machines for firing pellets is adopted. In this method, the layer of pellets and kilns are heated with a gradual increase in temperature.

carts to 650-850 ° C and cooling carts with pellets of atmospheric air.

The disadvantages of the method are the low resistance of the kiln carts due to the supply of cold air to the metal heated to 650-850 ° C and the increased energy costs due to the forced discharge of a portion of the heated gases to the chimney.

The aim of the invention is to increase equipment durability and reduce energy costs.

For this, in the method of operating conveyor machines for firing pellets, including the gradual heating of carts with pellets up to 650-850 ° C and their cooling, the cooling of carts with pellets is performed in two stages: the first carriage is cooled for 2-4.5 minutes the gases heated to 300-400 ° C, in the second stage, the carts with pellets are finally cooled with atmospheric air.

The method is carried out with a gradual increase in the temperature of the carts to 650,850 ° C. When metal carts are heated to temperatures below 650 ° C, the layer does not reach the technological firing temperatures of the pellets, their quality is low, the equipment performance decreases. At higher temperature carts (more than 850 ° C) their durability significantly decreases.

At the first stage of cooling, the agent heated to 300–400 ° C is filtered through pellets with pellets for 2-4.5 minutes. When the temperature of the agent is lower than 300 ° C, the durability of the carts decreases due to a significant thermal shock to the metal. The upper temperature range of the preheated agent (400 ° C) is limited by the conditions of its transportation. With a shorter duration of the first cooling stage (less than 2 minutes), the full heat recovery of exhaust gases is not ensured and, accordingly, the energy consumption for redistribution increases. With a longer duration of the first cooling stage (more than 4.5 minutes), due to an insufficient amount of cooling agent, the filtration rate of the gas through the bed decreases and the productivity of the calcining equipment decreases.

The drawing shows a schematic diagram (longitudinal section) of the baking conveyor machine with overflow collector.

 Raw iron ore pellets are loaded onto a calcining conveyor machine and subsequently subjected to drying, heating, firing, and cooling. Exhaust gas leaving section 1 of cooling

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the duct 2 is fed through the collector 3 into the blowing chambers 4, filtered through the calcining trolleys 5 and sent to the intake section 6 of the overflow manifold 7. The temperature of the calcining trolleys at the inlet to the cooling zone is 800 ° C. Reducing the temperature potential of the kiln carts when changing the direction of the heat flux is produced by using an agent heated to 370 ° C. The duration of the stay of the carts with pellets in the first stage of cooling is set to 3 minutes.

The application of the invention provides a reduction in the specific fuel consumption for redistribution and increase the durability of the kiln carts.

Claims (1)

Claims The method of operation of conveyor machines for roasting pellets, including heating a layer of pellets and roasting carts with a gradual increase in the temperature of the carts to 650-850 ° C and cooling the carts with pellets using atmospheric air as a cooling agent, characterized in that equipment durability and reduction of energy consumption, carts with pellets are cooled in two stages, and in the first stage they are cooled for 2-4.5 minutes with a stream of gases heated to 300-400 ° C from the last vacuum chambers of the cooling zone, and in the second stage the final cooling is carried out with atmospheric air.