Blow Heat Recovery

Modern blow heat systems have been developed by the innovative engineers at A.H. Lundberg, Inc. Since 1954, systems have been custom designed for pulp mills with batch digesters, continuous digesters, or a combination of both. Special demands and requirements of each system are incorporated into the designs. Blow steam is condensed for recovery of heat. Indirect condensers can be used, but most frequently the condensers are direct contact. The blow steam is intimately mixed with cooling water in direct contact condensers. In the primary condenser, cool water from the bottom of the accumulator tank is used to condense most of the steam. The heated water then enters the top of the accumulator. Continuously hot water can be withdrawn from the accumulator tank, heat transferred to other process steams, and cooled water returned to the bottom of the accumulator tank for use during the next blow.

Uncondensed steam and non-condensible gases pass on to a secondary condenser for condensation of remaining steam and cooling of the non-condensible gases. The secondary condenser can be either direct or indirect contact. In a batch digester blow system, the blow tank and steam piping is pressurized between blows. This prevents intrusion of air and dilution of non-condensible gases.

A.H. Lundberg, Inc., 2803 Hewitt Ave., PO. Box 1506, Everett, WA 98206. Tel: 425-258-4617; Fax: 425-259-1037.