Title

Blast Furnaces Pulverized Coal Injection Control Development Linked to Production Rythm

Blast Furnaces Pulverized Coal Injection Control Development Linked to Production Rythm

Authorship

CARVALHO, MARCELO ALVES DE; MOTTA, RICARDO SEBASTIÃO NADUR

CARVALHO, MARCELO ALVES DE

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MOTTA, RICARDO SEBASTIÃO NADUR

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DOI

10.5151/2594-357x-34Red-59-74

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Abstract

This paper subject aims to present CSN’s Blast Furnaces development and operational results with a new control mode the introduction for pulverized coal rate. The pulverized coal injection rate “set-point” in [ton/h], and dosing valve controller “set-point” used to be performed between two injection modes: by the Operator in [ton/h] or in cascade with flow signal of hot blast. In this mode the operator sets the set-point value in [g/Nm3], being that injection rate “set-point” in [ton/h] is calculated in function of the actual hot blast value. When hot blast flow drops, the injection rate follows it. On the other hand, as the hot blast flow varies, either, by natural oscillation or by stoves equalizing, the “set-point” in [ton/h] cascaded with the hot blast suffers interference, causing a higher coal rate variation. Also, this calculation used not to take into consideration oxygen enrichment, which affects the production. Besides, as there had not been any tracking between requested and calculated set-points, an undesirable step on the injection “set-point” was occurring whenever the mode should be changed, causing more variation in the injection rate. New injection mode in PCR allows operator to set PCR desired value in [kg/Ton hot metal]. Injection rate “set point” was cascaded with hot metal production rhythm in [Ton hot metal/min], besides performing the tracking between “set-points”, a higher stability in the furnace thermal level occurred in function of coal injection (power balance) being cascaded with production rhythm. The results of deviation on the quality of produced hot metal are lower and the increase of productivity is higher, as we are to see in the work.

This paper subject aims to present CSN’s Blast Furnaces development and operational results with a new control mode the introduction for pulverized coal rate. The pulverized coal injection rate “set-point” in [ton/h], and dosing valve controller “set-point” used to be performed between two injection modes: by the Operator in [ton/h] or in cascade with flow signal of hot blast. In this mode the operator sets the set-point value in [g/Nm3], being that injection rate “set-point” in [ton/h] is calculated in function of the actual hot blast value. When hot blast flow drops, the injection rate follows it. On the other hand, as the hot blast flow varies, either, by natural oscillation or by stoves equalizing, the “set-point” in [ton/h] cascaded with the hot blast suffers interference, causing a higher coal rate variation. Also, this calculation used not to take into consideration oxygen enrichment, which affects the production. Besides, as there had not been any tracking between requested and calculated set-points, an undesirable step on the injection “set-point” was occurring whenever the mode should be changed, causing more variation in the injection rate. New injection mode in PCR allows operator to set PCR desired value in [kg/Ton hot metal]. Injection rate “set point” was cascaded with hot metal production rhythm in [Ton hot metal/min], besides performing the tracking between “set-points”, a higher stability in the furnace thermal level occurred in function of coal injection (power balance) being cascaded with production rhythm. The results of deviation on the quality of produced hot metal are lower and the increase of productivity is higher, as we are to see in the work.

Keywords

Hot metal, pulverized coal

Hot metal, pulverized coal