Why the roots blower is used in the melt blown cloth equipment?
It is necessary to use roots blower. The reason why other types of blowers are not used is the production process of melt blown cloth. As we all know, the main raw material for mask production is melt blown cloth. The production of melt blown cloth is not a highly difficult process in the current Chinese chemical industry. The main reason why the price of melt blown cloth has been rising since April is that the downstream demand is in short supply and a large number of middlemen hope to make a profit from it. We started to resell and sell inferior meltblown cloth.
As a matter of fact, the chemical enterprises that make the melt blown cloth in China produce enough melt blown cloth for domestic and even export use. Production process of melt blown cloth production process of melt blown cloth is divided into: polymer preparation → melt extrusion → metering pump → melt blown die head assembly → melt fine flow drawing → cooling → receiving device.
The melt blown nonwovens process is to draft the polymer melt fine flow extruded from the spinneret hole of die head by using high-speed hot air, so as to form superfine fibers and agglomerate them on the condensing net curtain or roller, and become nonwovens by self adhesion. To put it simply, high-pressure hot air is used to blow out polypropylene in the molten state, and then in the process of blowing out, it naturally cools down, forms a silk, and forms a cloth. This is also the source of the melt blown cloth.
There are two kinds of spraying: one is horizontal form, the other is vertical form.
Equipment composition of melt blown cloth: main equipment: feeding machine, screw extruder, metering pump, melt blown die head assembly, air compressor, air heater, receiving device, winding device. In the production of polyester and other raw materials, a chip drying device is also needed. Production auxiliaries mainly include mold cleaning furnace, electrostatic applicator and spray device.
< level is melt blown Equipment > in the whole equipment, we see a relatively important thing: that is to say, the polypropylene solution is blown out by the high-pressure air flow that needs to be heated, which is the key point: Roots blower. The role of Roots blower in the production of melt blown cloth roots blower is to transport the heated high-pressure air flow stably under the condition of precise control of flow, high purity and high pressure. Why do I add so many adjectives when describing the function of Roots blower above? Let's talk about it one by one.
1. Control flow accurately. In industrial production, we generally don't talk about how much the wind speed is, but about the flow. Because the flow corresponds to: speed, sectional area of the tuyere. Because the length of the filament of the melt blown cloth can be adjusted. If the flow rate is too large, the polypropylene will be blown into dots. If the flow is too small and the filament is too long, the dust-proof effect may not be achieved. Therefore, we can't use this hot air supply mode, or simply use a household electric motor with an impeller to directly supply air.
2. During the preparation of high pressure melt blown cloth, we can see that it needs a certain pressure to send polypropylene to the molding belt in the distance for solidification. At the same time, stable high pressure also means better temperature control. As we all know, we take a breath and get cold soon after we go out. However, at higher pressure, it can effectively ensure that the polypropylene liquid will not solidify prematurely at a certain stage. Know that the left rear part falls on the molding belt to cool and solidify. This is equivalent to a hot air "escort" process. At present, there are three kinds of blowers that can provide high pressure: reciprocating compressor (i.e. piston type compressor), roots blower, blade blower (also known as three blade roots blower), centrifugal compressor. The main reason why reciprocating compressor is not used is that the speed is slow and the flow is small, which is not suitable in the production of melt blown cloth.
Centrifugal compressor, in the development of new technology, can really achieve high pressure output, but this high pressure output of the centrifugal compressor, cost ratio is high. Economically inappropriate.
Compared with these two, roots blower is better, because it adopts rotary mechanical air compression mode.