GENERAL
Paper machine wet end produces maximum heat from various motors and also generates huge amount of moisture as "free evaporation" from stock on the wire part. Another major source of moisture is water mist generated inside and under the wire. Thus, Wet end is a very important part of the paper machine when the machine hall air -flow dimensioning is considered. The importance of wet end ventilation system is not normally recognized and the consequences can be very serious resulting in quality/ production losses due to condensate dripping and fast deterioration of machinery and building structures.

DESCRIPTION
Sonar-DNB wet end ventilation system is based on knowledge & experience of different paper machine wet end applications and theoretical calculations of evaporation and air movements of moving fabrics. We had designed various kinds of configurations of wire exhaust systems for different types of paper and board machines. The wet end ventilation system consists of the following components:

• wire exhaust air headers located inside/outside the wire loops
• exhaust ducting for wire pits
• water eliminators, equipped with continuous washing devices if necessary
• exhaust air fan(s) connected to the air ducting
• exhaust air ducting to the atmosphere
• general exhaust system for wire and press sections which removes moist air from drive side of paper machine. This system prevents the moist air movements towards working areas etc.