Jinling Machinery-Vacuum System of Paper Machine

　　In the auxiliary system of the paper machine, the energy consumption of the vacuum system accounts for 30% to 40% of the entire system, and some are even higher.

　　Problems faced by the vacuum system

　　In the paper machine auxiliary system, the vacuum system occupies an extremely important position in terms of energy consumption and equipment investment.

　　Modern paper machines have an increasing range of speed and quantitative changes, and paper grades also change with market changes. The vacuum system is facing severe challenges:

　　(1) The vacuum system must be refined to adapt to changes in paper basis weight and vehicle speed;

　　(2) The vacuum system must be adapted to the different use stages of the paper machine forming wire and felt;

　　The vacuum system must provide optimized water and electricity consumption and save energy.

　　Comparison of two vacuum systems

　　water ring vacuum pump vacuum system

　　The principle of 　　 water ring vacuum pump will not be repeated here, many materials are introduced. The vacuum system of the paper machine is shown in Figure 1. In the actual design process, some other vacuum systems are derived from this, but the basic core has not changed, mainly including steam-water separator, water ring vacuum pump, vacuum pump water ring water system ( Vacuum pump water collection tank, self-priming tank, cooling tower and other equipment).

　　Inverter turbine vacuum system

　　The working principle of the turbine vacuum pump: the steam-water mixture from each vacuum suction point of the paper machine enters the special steam-water separator, the liquid and the lost fine fibers are pumped out through the pump installed at the lower part of the gas-water separator, and the gas enters the turbine vacuum pump after the filter . The gas is accompanied by the rotation of the impeller of the turbo vacuum pump, enters the hole in the middle of the impeller, and is accelerated and pressurized by the radial rotation of the impeller. Turbine vacuum pumps generally use a multi-stage turbine vacuum pump and two single-stage turbine vacuum pumps to meet the vacuum requirements of different suction points of the paper machine.

　　Turbine vacuum pump application case

　　The total installed capacity of the turbine vacuum pump is 1315kW, the total installed capacity of the water ring vacuum pump is 1830 kW, and the turbine vacuum pump system saves about 28% of the installed capacity. The main reason is that the turbo vacuum pump has an ultra-high efficiency of 80%, while the traditional water ring vacuum pump is only 40% to 50%, or even lower.

　　During the operation stage of the paper machine, due to the flexible use of the turbo vacuum pump, the energy saving effect will be more obvious when producing low-quantity products. On the other hand, the turbine vacuum pump system has no water ring vacuum pump water ring water system, which further saves the power consumption of circulating water pumps and cooling towers. The total water ring water system in this project is 67.5kW.

　　water consumption comparison

　　Water ring vacuum pump uses water ring water circulation, only considering power consumption, without considering water replenishment; the water ring vacuum pumps were all belt drive before the project transformation, packing sealing water was about 40 L·min-1, and the total cooling water in the lubricating oil station of the turbine vacuum pump 30~40 L·min-1, in the vacuum system of a large paper machine, the water ring vacuum pump generally adopts coupling transmission, and also requires lubricating oil cooling water. Turbine vacuum pumps have advantages in water saving.

　　Equipment layout and civil construction costs

　　In the design of a conventional paper machine plant, the wet end drive side is usually equipped with a flow system, a vacuum system, dense pipelines, many equipment, and limited space. Especially for paper machines with multiple presses, the wet end drive side has a further space.

　　steps are compressed, the equipment layout is very compact, there are many pipe elbows, and the pressure drop loss is large. The turbo vacuum pump system adopts a multiple process design with one belt to reduce the length of the pipeline. The number of equipment is 50% less than that of a water ring vacuum pump.

　　to more, flexible layout, it can be arranged on the first floor or on the second floor, greatly reducing the space occupied by the vacuum system.

　　(1) Only the footprint of the pump room is considered here, and the footprint of the pre-separator of the water ring vacuum pump system is not considered. The water ring vacuum pump originally occupies an area of ??6.5 m×36 m, while the turbo vacuum pump occupies only 6.5 m×18 m, saving 50% of floor space.

　　(2) The turbine vacuum pump system does not have a water ring water system, and does not require the water ring water collection tank of the water ring vacuum pump system. Only the equipment foundation of the turbine vacuum pump and the steam-water separator is designed and constructed, which is about 90% less than the water ring vacuum pump system. Civil construction costs.

　　heat recovery

　　water ring vacuum pump exhaust due to low grade, basically has no recycling value, most of them are directly emptied; while turbo vacuum pump exhaust temperature is high (about 140 ℃), low moisture content, can be used for heating and humidity

　　The 　　 part of the ceiling supply air can also be heated by the air hood, and the electric energy is converted into heat energy, which improves the utilization efficiency of electric energy to achieve the purpose of energy saving and consumption reduction.

　　The turbo vacuum system has the characteristics of water, electricity and land saving.

　　During the renovation of the project, some business owners doubted its actual use effect. It is recommended that the press section should first use a turbine fan, because the dehydration of the press section is much smaller than that of the wire section. For a long time, the water ring vacuum pump has matured

　　Reliable is the choice of papermaking vacuum system. However, in the face of the country's national strategy of vigorously promoting energy saving and emission reduction, companies must also make changes. The price and maintenance costs of turbo vacuum pumps make many companies look away.