【JST-034】One-on-one Q&A office for chemical mixing machinery design, manufacturing, inspection and maintenance

Mixing selection and power calculation: 1. The calculation formula of the mixing shaft is generally N=Np•n3•dj5•ρ. Among them, what are the values ​​of Np for disc/tooth blade propellers? Thank you 2. It is known that the viscosity of the mixing material is less than 350,000 centipoise (the lowest is a few hundred), the barrel (diameter is 1.2 meters, the highest is 1.9 meters, the lowest is 0.8 meters), and the single-shaft lifting type mixing (speed 100~800Rpm), what is the appropriate power (frequency conversion) to select? Thank you, host!

This post was last posted by yuxuan524177 on 2012-6-18 15:39 Editor 1. Regarding the disc stirring, it is a stirrer independently developed by us, and the use effect is pretty good. However, there is currently no book on the power coefficient Np of butterfly stirring. However, it should also conform to the stirring power calculation formula. According to experience, you can take a value of no more than 1 for this power standard. As for the power correction coefficient, you can take 1-1.5 according to the form of the mixer. This calculated value should not be very far from correct use. As for the power accuracy of the zigzag stirrer (dispersion disk) for a single layer, it can be around 0.2-0.35. 2. As for your power calculation, you need to give strict correspondence, such as the size of the kettle body (diameter, height, head form), and the viscosity and density. I will choose a more suitable agitator based on these parameters and calculate the power. What you said is more approximate, I can't calculate it. Another question, your viscosity is around 300,000 CPS, but the speed is 100-800rpm. What kind of mixer are you going to use? Isn’t the speed a bit high? ! !

Regarding what you said, "We plan to use different blades to stir at low speed when the viscosity is high and at high speed when the viscosity is low. This has a wider scope of application. ”It seems that the viscosity of your materials changes with the increase of heating, stirring, or mixing reaction time. This puts higher requirements on the mixer, which can adapt to high viscosity and low viscosity. However, I think the mixing effect of the same mixer may not be very good, and it also requires high motor power, has a large range of speed changes, and causes great damage to the motor and other undesirable factors. I suggest using a twin-shaft mixer, one with low speed and one with high speed, so that your requirements can be met, and everything I mentioned above can also be solved.

One is low speed and the other is high speed, so that your requirements can be met.

Come in and learn* study * . Share your opinions. I have been confused about the power of the mixing equipment, especially the power calculation of the eccentric mixer. I would like to thank you if anyone can help me. :D

The power calculation is only a reference value, and the most important thing is the empirical value. For the calculation of eccentricity, you can still use the power calculation formula, but eccentricity will increase the power loss compared to non-eccentricity, just like the baffle on power loss. There is currently no clear data to explain the impact of this. You can imagine the impact based on the actual eccentricity, and then consider a coefficient, such as a power correction coefficient of 1.2-1.5, etc. I think this should be enough.

Can LZ explain the selection of single and double pivot racks, as well as the selection of packing seals and mechanical seals based on actual experience? Thank you.

This post was last edited by yuxuan524177 on 2012-7-12 12:46 The selection of single and double pivot racks generally speaking, high speed, above 150rpm will use double pivots, and there is no bottom support at the bottom.； In addition, for those with high viscosity and mechanical seals, double pivots may also be used, and the bottom is equipped with a bottom support at the same time. However, double pivots require higher centering accuracy. Single pivots are generally used at low speeds and low viscosity, or used in conjunction with bottom supports. The requirements for centering accuracy are slightly lower. For those used with the bottom support, you need to pay attention to the coaxiality with the bottom support. Generally speaking, for packing seals and mechanical seals, packing seals or mechanical seals can be used for low speeds, only mechanical seals can be used for high speeds, packings can be used for medium and low pressures, and mechanical seals can be used for high pressures. ； The most important thing is that the choice depends on the characteristics of the medium and the working conditions. For example, for horizontal mixing, packing seals are generally used. Machine seals are easy to damage, and replacement is troublesome and frequent. Another important point is that for media with highly toxic or extremely harmful media, mechanical seals or magnetic seals will be used. Theoretically filler selection: Theoretically, mechanical seal selection :

This post was last edited by indifferent life on 2012-8-14 21:58 seal or glands single dry seal Who is a professional English speaker? Can you tell me if this is dry gas sealing or dry sealing?

In the single-span shaft system calibration, in addition to calculating the mixing shaft diameter according to strength and meeting the first critical speed requirements, what other factors cause resonance of the mixing shaft?