The application principle of roots pump in papermaking industry
At home and abroad in the recent ten years, has set up a file in the vacuum system of paper machine, widely used in the roots vacuum pump, roots pump specifications should, of course, and the specifications of the paper machine manufacture paper with pulp and paper of the relevant technology, such as matching requirement, can obtain satisfactory results.
The main advantages of using this vacuum pump device and the relevant equipment are as follows:
(1) to reduce power consumption In general, the consumption of roots pump power only 40% - 40% of consumed power by other equipment, to get such saving effect, is due to the use of the roots vacuum pump with gas water separation devices and USES the self-priming centrifugal pump.
Comparison example: for a container with a capacity of 52m3/min, the vacuum degree needs to be drawn to 4x104Pa(absolute pressure is 6x104 Pa), and the power on the pump shaft is compared: the liquid ring pump is 95 horsepower, and the tolerance between capacity and power is plus or minus 10%. For example, the single-stage roots pump is 55 horsepower, capacity and power tolerance is plus or minus 5%.
(2) the flexible operation of pump capacity adjustment device is available to adjust to the required value, but also a certain minimum value, power type roots vacuum pump belongs to the variable volume, can take 25% of reserves, thoughtless if required throughput due to manufacture more (or less), the correct processing method is to change the pulley diameter and rotational speed change, can achieve the desired operation effect.
The roots pump is a variable-volume pump, so its capacity is proportional to the rotating speed, and the power required is proportional to the speed and pressure.
In various cases, the roots vacuum pump can reduce the speed by 50% and can also guarantee the above advantages.
(3) improve the working quality of vacuum degree can be obtained by certain method, and has nothing to do with the amount of water in the pump suction, when producing sheepskin in print, has v roller is installed on a liquid ring vacuum pump and pay attention to the change of all kinds of vacuum degree, the absolute pressure of 40 ~ 45 MMHG. A separator and a roots pump are installed on the vacuum roller, and the absolute pressure is measured at 5mmHg with the same recording instrument.
(4) once the self-protection paper machine is in operation, don't stop working. In the practical work, a self-protection system is adopted, which consists of two completely identical interchangeable pumps to form the secondary pump group and is driven by only one motor. Eleven stop working and the other can continue working. But the pipes should be laid well. At this point, the line speed and vacuum may be temporarily slightly reduced.
(5) the four basic methods commonly used its basic method is: (1) with separator, vacuum pump (2) separation device in the network and fleece part, (3) in order to ensure that the vacuum degree of each paper machines, can establish a central vacuum unit, (4) separation device can solve the problem of high vacuum degree and low vacuum degree.
(6) vacuum unit can be installed in any suitable position In view of the roots vacuum pump suction air only, can literally be placed far from the vacuum point within 100 m, the only need to pay attention to is the air through the pipeline to produce differential pressure (the pressure difference effect). It is preferable to avoid the low pressure area in the pipe.
Separate air and water separators (columnar landing separators, separation tanks, etc.) are installed in closed systems with vacuum points.
(7) water immersed in the pump is no nuisance to the roots vacuum pump is able to withstand occasional water immersion. It can draw water out.
(8) without any maintenance to reduce maintenance workload, is due to: (1) gas, water separation to avoid damage by corrosion and abrasion, the machine (2) is decided by the structure of roots pump (due to the mutual contact between parts).
(9) almost no water consumption no or very little water consumption. The roots pump reduces water consumption. Generally, the liquid ring pump with a capacity of 52m3/min needs at least 10,000L/h of pure calcium free cold water to obtain the vacuum degree of 300mmHg, while the roots vacuum pump can operate without water or a little water.
For a higher vacuum, a combination of two or three pumps (in series with two or three pumps) is recommended, with minimal water penetration (about 400L/h).
The purpose of infiltration of water is to improve the volumetric efficiency of the pump by using the heat generated by the compressed air. Torque gets the minimum power to use.