METHOD OF BATCH FURNACE OPERATION, INCLUDING PRELIMINARY HEATING OF FLUID MEDIUM UPSTREAM OF FURNACE Russian patent published in 2020 - IPC F23L15/04 F27D17/00 F27B3/20 F27B7/34 

FIELD: power engineering.

SUBSTANCE: method of operating furnace (1) includes a heating step, in which fuel and an oxidant are fed into furnace (1), furnace (1) is heated by combustion of fuel with an oxidant to form heat and exhaust gases (10), wherein off-gases (10) are discharged from furnace (1) through pipe (11). At least one fluid (40) selected from fuel and oxidant is preheated upstream of furnace (1): by injection of liquid or gaseous medium (31) into chamber (20) with flow rate Dm>0 and by heating said medium (31) by heat exchange with exhaust gases (10) in pipe (11) through first wall (21), which separates medium (31) in chamber (20) from offgas (10) in pipe (11) to produce heated medium (32), and by pumping with flow rate Df>0 of fluid to be preheated (40), at least one line (41) in order to pre-heat fluid medium (40) by heat exchange with heated medium (32) in chamber (20) through second wall, which separates fluid medium (40) in at least one line (41) from heated medium (32) in chamber (20) and which has a temperature called working temperature. Method includes repeated cycles of heating stage, followed by stage of stop and stage of repeated start. During the stop phase, supply of fuel and oxidizer to furnace (1), combustion of fuel with oxidizer in furnace (1) and removal of exhaust gases (10) from furnace (1) through pipe (11) is interrupted; and flow rate Dm of medium (31) in chamber (20) does not exceed 50 %, preferably does not exceed 75 % and more preferably does not exceed 90 % of flow rate Dm during heating stage. During the re-starting step, supply of fuel and oxidant to furnace (1), combustion of fuel with oxidizer in furnace (1) and removal of offgas (10) from furnace (1) through pipe (11) is restarted; and medium is pumped into chamber (31) with flow rate Dm, which is greater than flow rate Dm during stop phase, and flow rate Dm is controlled in order to limit heating rate of first wall (21) during re-start phase, until first wall (21) reaches working temperature at the end of re-start phase.

EFFECT: invention ensures reliable and efficient utilization of heat of exhaust gases for furnaces of periodic action by means of indirect preheating technology.

15 cl, 3 dwg