There are many problems in the process of starting and stopping the meltblown non-woven machine. We need to pay attention to them. If we do not pay attention to these aspects, on the one hand, it will cause the quality of the melt-blown non-woven fabric produced, and on the other hand, it will also cause A damage to the melt blown non-woven fabric making machine.
Start-up and heating up of the meltblown non-woven fabric machine
For the new meltblown system in meltblown non-woven fabrics, when the system is started from the cold state for the first time, it includes screw extruder, melt filter, melts pipe, spinning pump, spinning box, and drafting air. The heaters and other equipment must be heated simultaneously, and all equipment must be in a normal state. During the heating period, the spinning system should be in an offline position.
1. Heating method
After the new spinning box has passed the 65°C low-temperature heating test, after confirming that the system's technical status is normal, the rate of 15-20°C/hour can be increased from room temperature, 65°C, 160°C, 265°C (or the temperature required by the process) The temperature is raised in four stages, and each time is kept for about 1 hour. After the temperature is stable, the temperature is raised. During the temperature rise stage, all heaters should be put into operation, and the temperature of the spinning box should be evenly distributed.
2. Management work during the warming up period
The management work during the heating and heating period of the spinning box can refer to the spunbond system. When the temperature reaches the set value, an equilibrium holding time of 0.5 to 1h must be required to ensure that the melt in the system can be completely melted and can flow normally. Depending on the ambient temperature and the configured heating power, the spinning box will heat up from the cold state to start up and run, and the required time is 3-4h.
During the heating and heating of the spinning box, the remaining oil on the spinning box, melt pipe, hot air pipe, and moisture in the insulation layer will vaporize or evaporate, and some white smoke will be emitted at these parts. , It will also produce a burnt odor. After about 30 minutes, the amount of smoke produced will gradually decrease, and the smell will fade and disappear. This is a normal process.
Therefore, there must be personnel to monitor at the test site, and careful inspection must be performed when abnormalities occur, and the test can only be continued after troubleshooting. A certain number of dry powder fire extinguishers should be prepared on-site for urgent needs.
During normal production and operation, the heating process can be accelerated without the need for heat preservation. Depending on the temperature at the beginning of the heating process, when the temperature reaches the set value, an equilibrium holding time of 0.5-1 hours must be required to ensure that the melt in the system has been It is completely melted and can flow normally. This is particularly important for production lines that use sleeve-cylinder melt filters, because the heating time required for this type of filter can reach 6-8h.
In order to avoid the "overshoot" phenomenon in which the temperature greatly exceeds the set value during the heating process, a gradual approach can be adopted, that is, the temperature rise is set in stages, rather than the one-time setting method of "one step". It can alleviate the "overshoot" phenomenon and shorten the transition spinning time after starting up.
Shutdown and cooling of meltblown non-woven fabric machine
When the system is scheduled to stop, first reduce the spinning pump speed to a state where it can maintain normal spinning, increase the DCD, move the spinning box (or net forming machine) to the "offline" position, and then proceed according to actual needs The following corresponding operations.
If the system is temporarily shut down, the system should continue to maintain the low-speed spinning state, or it can be considered to remain in the online position, but the net-forming machine should be kept in operation.
If the system needs to be shut down for a short period of time (such as several hours or longer), first close the feed valve of the screw extruder, and the system will continue spinning at a low pump speed, after all the melt in the system is discharged. , Terminate the operation of the spinning pump of the screw extruder, and the drafting fan and hot air system have to keep running at a low speed until the spinneret basically has no fiber ejected. After that, the temperature is lowered to 160-170°C to keep warm, and then the operation of other equipment is stopped.
This method is often used to stop the spinning unit when disassembling the spinning assembly, but the temperature is generally above 200°C. Before the spinning pump stops running, the drafting airflow must be kept in working condition. In the case of a short-term shutdown, this method can reduce the amount of polymer that is degraded in the system. When restarting, it is easier to heat up and can keep the spinning assembly in a more normal technical state and put it into operation again. If the downtime is not too long, just stop the spinning pump.
If the system is to terminate the production operation, it is necessary to close the valve of the screw extruder's feed port and operate it manually. After all the melt in the system is discharged, the operation of the spinning pump of the screw extruder is terminated, and the heating is cut off. System power supply, cooling, and shutdown. When this method is used to stop the machine, the remaining melt in the system will be degraded (yellowed) or carbonized, which is easy to block the spinneret holes. Therefore, the spinning assembly is generally replaced when the production is resumed.
So if we want to produce high-quality meltblown non-woven fabrics, we must choose high-quality melt-blown non-woven fabric machine. As a professional meltblown machine manufacturer, we have established a complete quality control system and provide customers with high-quality services. If you want to learn about related customized services and solutions, please contact us immediately!