Optimizing paper machine vacuum system
 

Optimizing paper machine vacuum system with Turbo Blowers

Vacuum, which is a result of air being pulled through a restriction, is an expensive tool; it is one of the top three energy consumers in a paper mill. Runtech’s RunEco vacuum system is developed especially to take into account the challenges and demands related to the dewatering and runnability of paper and board machines. Traditional method of increasing vacuum levels is replaced with speed adjustable turbo blowers, optimal doctoring and save-all systems with online dewatering measurements. By using only the needed vacuum in the critical consumers, mills can fully benefit from the more efficient nip dewatering strategy and save energy.

Operation Principles

There are some principles, which govern the content and operation of an efficient and eco-friendly paper machine vacuum system. The primary function of a wire- and press section i.e. the removal of water needs to be carried out effectively and reliably. This requires speed-controllable turbo blowers to create the needed optimal vacuum level, robust dewatering equipment such as save-alls and doctoring and means to measure all this reliably to get the feedback for the energy-efficient control of the system.

Vacuum is created as a result of moving air across a restriction. Fans, turbo blowers and liquid ring pumps can each be used to achieve this goal and are also often used in combination with each other. Turbo blowers have the benefit of being an inherently efficient way of compressing air for the modest compression ratios (less than 3.5) faced in a paper machine. A turbo blower is, for a given rotational speed and impeller design, a constant compression ratio device as opposed to a liquid ring pump which is a constant displacement machine. The power consumption of a turbo blower is a function of the air flow that is being compressed to satisfy the pre-determined compression ratio. A constant speed turbo blower has a limited range of efficient operation since the paper machine vacuum adjustment outside of the designed level requires throttling.


paper machine vacuum optimizing graph
Operating window comparison
en-IT