Rotary vacuum pump of contact evaporation process
The conventional contact steaming process conditions are rigid, ignoring the mutual influence of each process condition, and emphasizing the breakthrough and improvement of single index, which can not give full play to the role of contact steaming process. In order to deepen the understanding of the contact evaporation process and explore the application effect of the contact evaporation process under vacuum conditions, this paper introduces the application of the imported rotary vane vacuum pump in the contact evaporation process.
The external contact steaming process before cocoon cooking has been recognized and accepted by many manufacturers for improving cocoon quality, improving reelability, reducing the difference of falling thread among the outer, middle and inner layers, especially for improving the cleaning performance of factory silk. It has gained rich experience. Now we will introduce the
working principle of the rotary vane vacuum pump in the actual production.
Rotary vane vacuum pump of working principle
When the rotor rotates in the direction shown in the figure, the volume of space a connected with the suction port increases continuously, and the pressure in space a decreases continuously. When the pressure in space a is lower than the pressure in the pumped container, according to the principle of gas pressure balance, the pumped gas is continuously Suction chamber a is in the process of suction. The volume of cavity B is decreasing and the pressure is increasing, which is in the process of compression. The volume of space C connected with the exhaust port is further reduced, and the pressure of space C is further increased. When the pressure of the gas is greater than the exhaust pressure, the compressed gas pushes the exhaust valve, and the extracted gas continuously passes through the oil layer in the oil tank and discharges to the atmosphere. During the continuous operation of the pump, the process of suction, compression and exhaust is continuously carried out, so as to achieve continuous operation Purpose of air extraction.
Rotary vane vacuum pump in contact evaporation process of application
1. Using vacuum contact evaporation process can shorten the contact evaporation treatment time. Generally, it takes 10-15min (i.e. heating time) for conventional contact evaporation from opening the steam inlet valve to reaching the target temperature, and it also takes 10-15min for suffocation process. The whole process takes about 25-30min. A double barrel stainless steel contact evaporation pre processor can handle 4-6 cocoons per hour. However, with the use of vacuum contact steamer, the resistance of steam entering into cocoon cavity is small and the heating time is greatly shortened, only 0.5min is needed, and the holding time can be appropriately shortened, which improves the production capacity of the contact steamer.
2. The effect of conventional and vacuum contact steaming on improving cocoon quality and silk quality is significant. Vacuum contact steaming is slightly better than conventional contact steaming. This is because, due to the existence of vacuum, steam can reach the cocoon cavity more quickly and more evenly through the cocoon layer, the degree of action of the outer, middle and inner cocoon layers tends to cause, the extent of sericin expansion is more uniform than that of conventional contact evaporation, because the difference of the falling thread rate of the outer, middle and inner layers decreases, while the effect of conventional contact evaporation on the outer layer is stronger.
3. In the process of vacuum contact steaming, the effect of steam on the cocoon layer is stronger, and the solubility of sericin is enhanced. When entering the steam, the principle of “small first, then large” should be mastered. In addition, the steaming time should be shortened appropriately to prevent sericin from over dissolving in cocoon cooking.
The application of the new technology of high-temperature and short-time cocoon cooking before contact steaming has achieved remarkable results in improving the quality of raw silk and reducing the consumption of raw materials. As the same as the normal cocoon, the silk sliver can be dissociated in order, which can reduce roughening and similar knots, improve cleaning performance and reduce reeling fold. This paper introduces the experience of the application of imported rotary vane vacuum pump in the contact evaporation process.