Rotary vane vacuum pump in leather wet processing
At present, vacuum technology is widely used in the production of light chemical industry and medicine, and leather industry is no exception. Traditional tanneries only carry out dry processing, and apply vacuum technology to wet processing of leather. Production efficiency and product quality are significantly improved, pollution is reduced, and development and application prospects are broad. Next, this paper introduces the application of the vacuum pump in leather wet processing, and makes a simple analysis of the main influencing factors of the vacuum pump for leather wet processing, hoping that more tanneries can help.
In vacuum technology, “vacuum” generally refers to the state of gas below one atmospheric pressure. Compared with normal atmosphere, it is a rarer gas state. The lower the pressure of the gas, the higher the vacuum degree; otherwise, the higher the pressure, the lower the vacuum degree.
Principle and technology of rotary vane vacuum pump for leather wet processing
The traditional wet process includes soaking, liming, depilation, deashing, softening, pickling, tanning, retanning, neutralization, dyeing and oiling. There are many problems in this method, such as complex process, long production cycle, large energy consumption and serious pollution.
Principle of leather vacuum wet processing
In the vacuum condition, the principle of vacuum impregnation is used to complete the material modification process through the contact between the material and the impregnating material, the adsorption of the material on the impregnating material, the diffusion of the components of the impregnating material to the internal structure of the material and the physical or chemical (biochemical) reaction between them.
The rotary vane vacuum pump is introduced into the leather wet processing process. By using the appropriate process and equipment conditions, and on the premise of meeting various performance indexes of leather, the fast wet processing process of leather with less pollution is found out, and the corresponding design and research of leather vacuum wet processing equipment are carried out, so that the disadvantages of long production cycle and large pollution degree that are difficult to overcome in conventional wet processing can be solved. The operation time of the process with long time consumption is more than 60% less than that of the conventional processing method; the alkali consumption of Liming and unhairing is reduced by 50%; the consumption of chrome tanning agent is reduced by 20%; the reuse rate of the operation waste liquid is high, for example, the chrome tanning waste liquid can be reused at least 10 times after the composition is adjusted; the pollution is greatly reduced in the recovery and recycling of the operation liquid, the work efficiency is improved, the energy consumption is reduced, and the automatic control of the processing process is realized The system has achieved remarkable results, the product quality has been improved, the social and economic benefits are obvious, and it has broad application prospects.
It can be concluded from the research on the application of rotary vane vacuum pump in leather wet processing that the main influencing factors are as follows:
1. Vacuum degree
According to different working procedures, reasonable vacuum degree can greatly reduce the processing time. For some processes, in the range of low vacuum, the improvement of vacuum degree does not show a greater effect. For some processes with high temperature, if the vacuum degree is too high, it will make the material liquid evaporate and have a negative impact. When the temperature is not more than 40, the vacuum degree of 4000Pa or so can achieve better results.
The higher the temperature is, the faster the diffusion is; the lighter the molecular weight is, the faster the diffusion is, so that the cycle of leather wet processing is obviously shortened and the efficiency is improved.
In the depilation and liming stage, increasing the temperature can speed up the penetration of alkali solution, improve the effect of depilant, shorten the Liming time, accelerate the saponification and depilation of oil, reduce the water filling degree of raw hide, and prevent the excessive expansion of raw hide during Liming.
3. Mechanical action
In the process of liming, there is little effect of rotation and static on the test results. However, in the processes of depilation and tanning, the result of static state is obviously worse than that of rotation state.