Oy Tampella Ab

Ari A Maijala

Matti I Aario

A method of improving the utilization of the heat energy produced in a wood grinding process when wood is ground in a grinding space (3) under a pressure exceeding atmospheric pressure, and warm shower water (G) is sprayed into the grinding space. Steam (H) is separated from the groundwood pulp (A) discharged from the grinding space in a steam separator wherein the groundwood pulp is allowed to expand from its inlet pressure to atmospheric pressure in at least two steam separators (11,14) by releasing steam from the groundwood pump in each steam separator by decreasing the pulp pressure. The amount of steam (H1,H2) released in the separate steam separators is adjusted according to the proportions in which steam is needed for utilizations purposes. Thus the heat energy of the pressure grinding process can be recovered in separate steam fractions the amount and pressure of which correspond to the requirements of the utilization purposes. It is preferable to heat the shower water by steam of such a volume and pressure that the temperature of the shower water increases to a desired degree, preferably above 100.degree. C.

Method of improving the utilization of the heat energy produced in a

A method for improving the utilization of the heat energy produced in a wood grinding process, wherein wood is ground in a grinding space (3) under a pressure exceeding atmospheric pressure, and warm shower water (G) is sprayed into the grinding space. The groundwood pulp (A) is fed from the grinding space into a steam separator (11), wherein the heat energy contained in the groundwood pulp is released in the form of steam (H), and replacement water (E) is brought into the process for the compensation of shower water losses. The steam separator is kept pressurized in order to recover the steam (H) released from the groundwood pulp under a greater pressure and at a higher temperature than in an atmospheric steam separator. The water addition (E) to the recovered shower water is warmed up by means of the pulp suspension (B) discharged from the steam separator, whereby the pressure of the steam is decreased from the pressure of the pulp suspension entering the steam separator only so much as is required for heating the replacement water to a temperature which will bring the shower water to the desired temperature after the replacement water has been mixed with said recovered shower water.

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Tampere, Finland

Ari A Maijala