Subject : Power Plant Engineering

Topic: Chap 6: Power Plant Economics

Difficulty: Medium

An economizer used in modern high pressure boilers is shown by a line sketch. It consists of a series of vertical tubes. These tubes are hydraulically pressed into the top and bottom headers. The bottom header is connected to feed pump. Top header is connected to the water space of the boiler. It is provided with a safety valve which opens when water pressure exceeds a certain limit. To keep the surface of the tubes clean from soot and ash deposits, scrapers are provided in the tubes. These scrapers are slowly moved up and down to clean the surfaces of the tubes. The action of adjacent pairs of scraper is in opposite direction. i.e., when one scraper moves up, the other moves down.