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

the draft to be created

limitation of construction facilities

control of pollution

quantity of flue gases to be handled