Re: Carbon Black Flow Problem In Hopper
Could you advise the barrel diameter and height of your hopper.
150mm diameter outlet does seem a little small. What is the residence time of the carbon black in the hopper? ■
Carbon Black Flow Problem
Dear Designer,
The material remains in main station for 2-3 days idle but not in conveying hopper. In conveying hopper it remains only for 5-6 minutes. I doubt that only in 6 minutes it gets stuck.
150 mm dia is small but we can't give bigger dia as this hopper outlet is connected with mixer inlet and high speed mixer has only 150 mm hole in it to connect the pipe.
We tried with pneumatic impacter but with no result.
This conveying hopper has bag filters and they cleans with Jet Pulse. How come carbon black remains there and not fall down with Jet pulse push on top of it ?
Regards.
Dhruv Shah ■
Re: Carbon Black Flow Problem In Hopper
Barrel means hopper and its diameter is 1500 mm but actually there is no height of hopper. to make 250 kg. batch, we only need to fill in cone portion up to when straight hopper start. Can this be a problem? ■
Hopper Flow Problem
The answer to your query as to why the carbon black does not flow down when there is an air pulse pressure on top of the contents is that loose solids do not behave like liquids and transmit hydraulic pressure through the bulk, but will consolidate to a stronger condition under such a pressure and become much worse for flow. The outlet size is small and I also suspect that the wall slope is not quite steep enough for mass flow,although this can easily be checked by wall friction tests. The name 'carbon black' is not adequate to define the material and a representative sample should have had the flow properties tested to establish a required design. It seem likely that this information would have confirmed that the outlet size should be bigger, in which case and in present circumstances the question is how to solve the dilemma. One approach is to fit a simple cone valve with parallel body, sized to create a suitable with of -flow annulus when lifted. For example: - lifting 350 mm will give a slot about 127 mm wide, which is equivalant to a circular orifice over 250 mm diameter, At a cone body diameter of 300 mm, the min slot length is almost two metres, and the flow channel has one vertical wall and one at 70 degrees as a vee, which is far superior to the original cone for flow. Lifting the valve will disturbe the contents to encourage flow t give a good chance of promoting flow. The main risk is that, even in a dynamic condition, the flow could overwhelm the 260 diameter outlet. Probably the safest option is to cut off part of the cone and fit a transformation section to a well designed screw feeder with mass flow characteristics, based on measured properties of the carbon black.
Sadly, the usual industrial approach is to try various methods of brute force, with unpredictable outcome, until something eventually works. ■
Carbon Black Flow Problem in Hopper
Dear sirs,
After installing the dilute phase vacuum conveying system we have carbon black in vacuum hopper which doesn't fall down by gravity. It happens only after 2 days.
The hopper angle is now 70 degree (from straight ground to inclined surface) and dia is 150 mm. We have installed 3 fluidized rubber cup (Air brater from Bin Master) at 120 degree @ 500 mm from bottom but result is not improved.
Kindly suggest what to add to make it right.
Dhruv Shah ■