from a metal wall from one medium to another

from heating an intermediate material and then heating the air from this material

by direct mixing

heat is transferred by bleeding some gas from furnace

approach temperature should be as low as possible

handling and maintenance should be easier

heat transfer area should be optimum

stack gases should not be cooled to the dew point

more

less

equal

may be more or less depending on capacity of reheater

create vacuum

inject chemical solution in feed pump

pump water, similar to boiler feed pump

add make up water in the system

higher value

lower value

same value

any value