1. The performance of activated alumina. Many production practices and research experiments have proved that different production plants or different batches of products in the same production plant have great differences in the ability to regenerate degradants. In these sex
Among the energy indicators, the physical properties such as crystal form, bulk density, strength, specific surface area, sodium oxide content, and water absorption have been evaluated and confirmed in practice for many years. And alumina in water, potassium carbonate solution
Or the working fluid does not become soft or crushed after long-term soaking. It has been proposed and gradually improved in recent years according to the requirements of the production process.
Dust is carried to other processes and seriously affects normal production. When the content of degradants is higher than 40 g L or more, the effective anthraquinone added value, if the new device is put into production using new working fluid or the content of degradants is low, then
This index cannot be determined and can only be determined based on the experience of using alumina on other devices.
2. Operating conditions of activated alumina. When the working fluid passes through the activated alumina, the regeneration effect can be very different due to the different operating conditions selected. (1) Activated alumina and working fluid
Contact time. At a constant temperature of 50℃, the effective anthraquinone content of the working fluid after the post-treatment and the activated alumina contact for different time before and after regeneration is measured. When the contact time is less than 0.5 h, the active oxygen
Aluminum fluoride has almost no regeneration effect, and the effect is best when exposed to more than 1.5 hours. At a constant temperature of 50 ℃, the change of anthraquinone content before and after regeneration when the hydrogenation solution contacts activated alumina is measured. 1) Working solution or hydrogenation solution
The longer the contact time with activated alumina, the better the regeneration effect, and the contact time is less than 0.5 h, the regeneration effect is not obvious. 2) Using different working fluids, due to the different composition and quantity of degradants,
The regeneration effect is also different. In production practice, the contact time between the working fluid and activated alumina is generally only 10 minutes or less, the regeneration effect is not obvious, and the components of the working fluid are unstable. Therefore, or
Try to increase the amount of activated alumina added, or allow a part of the working fluid to pass through the activated alumina bed, so as to increase the contact time to ensure the regeneration effect of activated alumina. Currently, generally not heavy
Depending on the use or even abandonment of the hydrogenated liquid regeneration bed, this is an important reason for the instability of the working fluid composition. Because in some production equipment, due to the different composition of degradation products (maybe more epoxides, hydrogen
The main function of chemical liquid regeneration is to regenerate epoxides) and the operating temperature is higher. At this time, the regeneration capacity of the hydrogenated liquid regeneration bed may be greater than that of the working liquid clay bed. (2) Activated alumina and working fluid
The contact temperature. When the contact time is 2 h, the anthraquinone changes before and after the working fluid is regenerated by activated alumina at different temperatures are measured. The regeneration effect of the working fluid in activated alumina is related to the temperature.
The effective anthraquinone content increases more after the temperature rises. In production practice, due to the low temperature of the working fluid after post-treatment, it can be preheated through the white clay bed, then cooled, and then dehydrogenated
Process method to improve the regeneration capacity, in order to save heat, a part of the working fluid can be passed through the white clay bed and operated at a higher temperature, and the other part can be bypassed and directly enter the storage tank. According to reports, when
When the temperature exceeds 100℃, the regeneration effect is more obvious, and further verification is needed. (3) The composition of the working fluid entering the white clay bed. The working fluid flows through the post-treatment process and undergoes K2CO3 treatment to remove moisture
And residual H2O2, but a small amount of lye is entrained in the working fluid. Production practice shows that if the working fluid entering the activated alumina bed entrains excess water, lye or H2O2, it will cause alumina regeneration.
Ability declines, even powdering. However, it is beneficial to maintain the proper alkalinity of activated alumina. There are patent reports that the Na2O content in alumina reaches 3.7%, which is beneficial to the regeneration of degradation products.
3. The structure of the activated alumina bed. The larger the contact area between the working fluid and the activated alumina, the more obvious the regeneration effect.
Activated alumina failed to participate in the reaction, which has been reflected in some production devices, that is, when the activated alumina is replaced, it is found that the color of some activated alumina has little change, and no or seldom participates in the reaction.
Affect the regeneration capacity of activated alumina. Therefore, it is recommended that when designing and selecting the alumina bed, consider appropriately increasing the height-to-diameter ratio so that the working fluid is fully in contact with the activated alumina.