Loss in Weight Feeders
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- เผยแพร่เมื่อ 30 ก.ค. 2024
- Loss in weight feeders consistent of a screw feeder that doses powder from a hopper. The hopper is periodically refilled by a much larger storage silo. The hopper is on weigh cells that continuously measure the weight of the powder in the hopper. The controller will determine how much weight it loses in a given amount of time. This loss in weight is interpreted as a flow rate.
The flow rate is continuously calculated while in gravimetric mode, which is when the hopper is not being filled. When it is being filled, it enters into volumetric mode, which is when the feeder has to make assumptions what the flow rate is. It has to make an assumption because there is a net gain in weight as it fills. The controller will make an educated guess as to what the screw feed needs to be. After the hopper is refilled, it enters back into gravimetric mode where the flow rate is continuously calculated and the screw speed adjusted accordingly.
This theory is sound, but data is not always so perfect in real life. When conditions are perfect, there is still some variation of the actual flow rate.
And when conditions are not perfect, the loss in weight feeder can only perform as it’s programmed. If there is a suction pulling the powder through the screw, it can cause the motor to slow down to an actual stand still. If there’s enough of a suction then powder can flood around the screw resulting in a flow rate even though the screw speed is 0% (stopped).
And when conditions turn really sour, the loss in weight feeder can give misinformation. Small increases in hopper weight can throw the feeder into a mode that is not gravimetric mode where it doesn’t actually know what the feed rate is.
Watch the video for a much better explanation :)
Very good explnation. Thank you
Thank you
Thanks for nice explanation, Need your help with more information on Volumetric feeder system where the flowrate can be controlled thru only rotary pump. In volumetric system do we have ways increase the effectiveness of the system
Thanks
When you have jumps in weight my guess you were adding material into a humid process. Most of the material enters the reservoir at a constant rate but you get some building up on the screw. It becomes wet and sticks to the screw until it reaches a critical mass where the weight of the build-up exceeds the skickyness of the material and it breaks free and falls into the tank. Hence the instantaneous spike in loss in weight is experienced. The vacuum is more interesting
Can you kindly give us your technical analysis to our current issues.
1. LIW is in stop mode and empty and has a readout value of -0.07kg fill in weight, however the flow rate is showing 1.7kg/Hr and not showing zero is there a way to make the flow rate zero without changing programs in the controller?
2. What are the possible factors that flow rate is not showing 0.0 kg/hr?
Thanks for the video. Do you know what is K-Cdr
page Mcn.01 stands for ? Because im having feedfactor issue and i refer the manual, it has a sentence that asked to see K-Cdr
page Mcn.01.
Thanks, why seperate controller is required, can we achieve the function with common PLC of other process
Net hopper weight, motor speed, and mass flow calculation formula please as the trend shows?
Could you please help me how to solve the formula for mass flow. I am having a hard time understanding it. Thank You
Can you tell me what information you have and what you are trying to calculate? My experiences have been centered around a simple equation. The total mass accumulated (kg) is equal to the flow rate (kg/hr) multiplied by time (hr). But, I'm guessing that's not what you're asking.
Process Engineer School Could I email the information to you? I just started as process engineer at my company
Luis Delgado Yep! mbutler5@gmail.com
What caused jumping in weight value? The load cells are were not accurate?
Thank you for useful video. I really need to help about gravimetric mode. Can i send you a mail about my problems?