Towards energy-efficient and economical Tissue production with RunEco vacuum solution

There are some principles, which govern the content and operation of an efficient and eco-friendly 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.

RunEco EP Turbo Blowers are designed to operate efficiently across a wide range of vacuum levels and air flows. It allows paper mills to optimize vacuum levels whilst taking advantage of the higher efficiency a blower has over a traditional liquid ring pump device.

High speed motors, driven by frequency converters, allow a typical RunEco blower to provide paper machine vacuum levels between 30 and 73 kPa (9” and 21” HgV). A wider range of impeller designs allows highly efficient levels across the operating range. This means that the amount and the usage of throttling valves can be reduced to a minimum. The result is energy savings of 30 to 70% when compared with traditional vacuum systems.

RELIABLE DEWATERING – THE BASIS FOR RUNNABILITY

Each vacuum element in the machine, such as a suction box or a suction roll, requires a certain amount of air flow to operate at an ideal vacuum level i.e. at the minimum to maximize the energy efficiency while maintaining the runnability and dewatering capacity.

The needed capacity is dependent e.g. on felt life and type, paper grade, basis weight, machine speed etc. To achieve this challenging goal we need reliable dewatering measurements. Runtech EcoFlow dewatering measurement system is designed to measure real time water flow accurately while not sensitive to entrained air or foaming. These devices are used both under vacuum (in a separator drop leg) and in atmospheric conditions.

The third fundamental issue in an energy efficient vacuum system is the dewatering and doctoring. These are not only related to energy consumption, but also play a major role in paper machine runnability (profiles), efficiency (dirt and breaks) and profitability. Therefore, a well-designed and operated dewatering and doctoring system is one of the key issues to a well-performing and energy-efficient machine. A lot a paper machines have them, but they are not effective and don’t have the adjustability that is needed to optimize them effectively.

The most economical method of water removal in a press section is nip dewatering, as opposed to felt dewatering requiring higher vacuum levels and thus energy demanding higher air flows. Fit-for-purpose doctoring and save-all equipment allows the felts to run wet collecting water in the pans enabling higher dewatering, higher felt lifetime and, for example better moisture profiles to improve runnability.

Suction rolls are often equipped with double doctors to prevent re-wetting and maximize void volume to allow best water removal. Save-all pans should be designed to manage the water that is removed from the nips and engineered to be rigid enough to accommodate doctor holders and have the adjustability to be effective. Runtech is one of the leading suppliers for the improved dewatering and doctoring solutions for all kinds of pulp, paper, board and tissue machines. In many cases, Runtech’s solutions have led to a 1-3% increase in dryness after the press section which saves considerable amount of energy in the dryer section (4-12% less steam).

ABOUT RUNTECH

Runtech Systems is a part of Ingersoll Rand. With years of hands-on papermaking know-how, Runtech develops, designs and supplies equipment and related services for paper, tissue and pulp mills. Hundreds of delivered systems, such as dewatering meters, vacuum systems, tail threading equipment and doctoring solutions benefit its customers by enabling energy-efficient and economical production. Its integrated solutions result in significant operational cost savings, improved machine runnability and product quality, giving a competitive edge for its customers in the market.