Method for regulating the pressure of blow-through discharge steam from a reboiler of process steam produced during production of mechanical pulp

摘要

A method and system for efficient heat recovery during the production of mechanical pulp treats the process steam inherently produced during the production of mechanical pulp to maximize the energy content of clean steam produced. Comminuted cellulosic material is refined in one or more refiners, and the mixture of mechanical pulp and process steam from the refiner is separated into process steam and pulp flows by a cyclone. The process steam is passed to a scrubber, and then to an inlet of a reboiler (steam transformer) which produces clean steam and discharged flow- through process steam. The conduit between the cyclone and the scrubber is open so that the pressure of the process steam before it enters the reboiler is not significantly affected; a buffer may be provided in the conduit, however, to damp process steam pressure variations. The pressure of the discharge blow through steam from the reboiler is regulated so as to maximize the energy content, pressure, and/or temperature of the clean steam produced, and the reboiler inherently acts as a buffer. This pressure regulation is practiced by providing a valve in the process steam outlet from the reboiler.