METHOD AND ARRANGEMENT FOR GENERATING STEAM AT A DIGESTER PLANT OF A CHEMICAL PULP MILL

摘要

The present invention relates to a method of producing steam at a digester plant of a chemical pulp mill. Black liquor is discharged from the digester (17) at a first temperature and pressure. The black liquor is treated in a flash tank (34) for generating flashed black liquor and flash steam at a second temperature and a second pressure, which are lower than the first temperature and pressure. The flashed black liquor (35) is taken for further treatment to the evaporation plant. The flash steam (38) is led to an indirect heat exchange contact with clean liquid in the reboiler (39) for boiling the liquid and for generating steam. The steam is led from the reboiler (39) into a fan or compressor (41) for increasing the steam pressure to a third pressure, which is higher than the second pressure and for adjusting the pressure of the steam in the flash tank. Steam at a third pressure is used for pretreating comminuted cellulosic fiber material, such as chips, prior to cooking.