A、help preheat the air for the furnaces
B、help preheat the feedwater
C、protect economizer from excessive heat
D、prevent excessive furnace heat losses
更多“One of the main purposes of refractories in a boiler furnace is to（）”相关的问题
A、one-half the SWL of the main towing hawser B、three-fourths the SWL of the main towing hawser C、that of the main towing hawser D、twice that of the main towing hawser
A、stuffing box diameter B、direction of rotation of the screws C、pitch of the screws D、type of driving gears
A、one automatic drain serving both containers B、two air starting containers of approximately equal size C、one control air container and one starting air container D、one additional means of starting the main engine
A、overspeed；overload B、overload；overspeed C、over torque；overspeed D、low mechanical efficiency；overload
A、the clearance of the main bearing B、the diameter of main bearing C、the gap of main beating D、the tolerance of main bearing
A、the clearance of the main bearing B、the diameter of main bearing C、the hardness of main bearing D、the tolerance of main bearing
A、the clearance of the main bearing B、the play of the miler bearing C、the gap of the main bearing D、the tolerance of the main bearing
A、The main body of a vessel is the hull. B、The main body of a vessel is the superstructure. C、The main body of a vessel is the engine room. D、The main body of a vessel is the poop.
A、A main query can have more than one subquery. B、A subquery can have more than one main query. C、The subquery and main query must retrieve data from the same table. D、The subquery and main query can retrieve data from different tables. E、Only one column or expression can be compared between the subquery and main query. F、Multiple columns or expression can be compared between the subquery and main query.
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