Vacuum system of tissue paper machine

The power consumption of vacuum system in tissue paper machine accounts for 20% ~ 25% of the total power consumption. Strict energy conservation and emission reduction policies and increasingly fierce market competition urge paper enterprises to seek space for energy conservation and consumption reduction.

With the development of science and technology, some paper-making enterprises began to optimize and upgrade the vacuum system, such as vacuum pump frequency conversion energy-saving transformation, vacuum pump servo motor energy-saving transformation, turbine vacuum pump application and so on.

Vacuum system of tissue paper machine is an important auxiliary system of paper machine. It is mainly used in the wire section and press part of paper machine, which plays the role of Web dehydration and transfer.

The vacuum system is generally composed of Roots vacuum pump or water ring vacuum pump. In the design process of vacuum system, 20% ~ 25% design margin is generally reserved, and the matching motors are power frequency motors. These design margins are the space where we can consider improvement and Optimization for energy saving and consumption reduction.

The purpose of this paper is to adjust the operating parameters of the vacuum pump according to the vacuum suction volume and vacuum degree required by the actual operation, reduce the interference of the vacuum system, and achieve the purpose of energy saving. At the same time, due to the high efficiency and energy saving characteristics of turbine vacuum pump, it began to replace roots vacuum pump and water ring vacuum pump commonly used in paper machine vacuum system.

Turbine vacuum pump replaces roots vacuum pump

The working principle of the turbine vacuum pump is to use the interaction between the blade and the gas, the high-speed rotation of the impeller, improve the gas pressure and kinetic energy, and use the successive flow components to slow down the flow, and change the kinetic energy into pressure energy.

In order to obtain the final required pressure, multi-stage combined compression is generally used. When used as a vacuum generator, the final discharge pressure is atmospheric pressure and the suction pressure is negative pressure. When turbine vacuum pump is used in vacuum system, the operating speed of impeller is higher. The operating speed of multistage machine is generally 5000r · min-1, and that of single-stage machine is more than 10000r · min-1.

Because the moisture or other foreign matters carried by the gas enter the high-speed moving turbine fan, it may cause fatal damage. Therefore, before the intake of the turbine fan, there must be a large-scale cement or stainless steel gas-water separation chamber to control the air flow speed within 3M · s-1.

When the air is accelerated to compress and release, it will produce large noise. When designing and installing, the turbine vacuum pump is generally installed in a relatively closed room to prevent noise diffusion.

Data comparison shows that: the energy saving of turbine vacuum pump is greater than that of the above two transformation methods, reaching 40% energy saving. The main reason is that the turbine vacuum pump has 80% super high efficiency, while the efficiency of traditional water ring vacuum pump or roots vacuum pump is only 40% ~ 50%, or even lower.

However, due to the high price of the pump body and the need to modify the vacuum pipeline, the payback period of the investment is about 19 months. However, energy saving is a long-term benefit. From a long-term point of view, it is a very good reconstruction project.

The paper drying should follow the rules: the total water amount of paper drying = press dehydration + vacuum suction dehydration + evaporation water. The greater the vacuum suction, the less the press dehydration and the increase of the paper machine transmission load. Compared with vacuum suction, the press dehydration has low energy consumption and high efficiency, which should be given priority to. Therefore, the reasonable vacuum pumping capacity is to reduce the energy consumption Important measures of consumption.

The reform methods of vacuum pump are to adjust the vacuum pumping capacity reasonably to match the production process requirements, so as to maximize the vacuum dehydration and press dehydration.

At the same time, due to the different transformation methods, the equipment efficiency is also different. Through comparison, from the long-term economic efficiency, the selection of turbine vacuum pump is the best. With the enhancement of domestic R & D and manufacturing strength and the reduction of equipment cost, it is believed that turbine vacuum pump will be widely used in China’s paper industry and contribute to the national energy saving and emission reduction goal.