Re: Calculation Mistake In An Article Of Mr. A.w. Roberts ?
He works as the university of newcastle.
Just look up tunra bulk solids on the net
Are you sure he has not used a higher bin ■
Re: Calculation Mistake In An Article Of Mr. A.w. Roberts ?
Took me some time, but i found the problem.
I made a mistake in my excel sheet ..... 
Its due to those cumbersome formula expressions 
Now, i got the same answers as prof Roberts ■
Re: Calculation Mistake In An Article Of Mr. A.w. Roberts ?
Do you have a copy of the sample question?
I have a spreadsheet that has be thoroughly tested.
I did not get the exact same answer.
The question I am working from may be from a different paper.
Send me an email if you like and we can share knowledge on this and possibly other subjects.
Best Regards,
Gareth Blakey
blakeyg@conwag.com ■
Re: Calculation Mistake In An Article Of Mr. A.w. Roberts ?
I got my information form the articles, listed in my first post.
I can't share the information i got atm, since i am doing this investigation for ESI/Eurosilo, and the sheet involves much information about knowledge, which much be kept within the compagny.
You could check if you got the same surcharge factor, as calculated by Mr Roberts in the article mentioned above. Do note that he uses the surcharge formula that gives better practical results for the feeder load during flow.
This 1 :
qf = (pi/4)^m x (Y(1 + sin ( delta))) / ( 2 (X - 1) sin ( alfa ))
From there you should be able to calculate the correct surcharge factor and the correct feeder load. The resistances to be calculated follow partly from these results and should not give many problems.
Gl, if you got questions, dont hesitate to ask them in this thread.
PS. note that for conditions under flow, the height of the bin is not relevant, because of an existing arched stress field in the hopper . ■
Calculation mistake in an article of Mr. A.W. Roberts ?
Mr. A.W. Roberts has made 2 very interesting articles, which are very usefull for my investigation towards hopper/feeder systems.
■
These articles are :
1 :
Wall pressure-feeder load interactions in mass flow hopper/feeder combinations part 1
(bulk solids handling, volume 6, number 4, august 1986)
2 :
Wall pressure-feeder load interactions in mass flow hopper/feeder combinations part 2
(bulk solids handling, volume 6, number 5, october 1986)
In the second article, Mr Roberts made a design example in which he calculates all the different factors that are of influence on the hopper/feeder design. Somewhere in this example, there is a calculation for the surcharge factor q during flow, which has a value of 1,05 .
In my opinion, this factor is a bit high. When i calculate this factor, using Mr Roberts his input, i get values for the surcharge factor q during flow of around 0,4 . Due to this difference, Mr Roberts gets much higher forces, acting on the feeder. This way, Mr Roberts also gets much higher requirements for the power of the belt feeder.
Rademacher also made calculations for this surcharge factor in 1 of his own articles, and also has numbers in the range of 0,4 for his calculation example. The power requirements, found by Mr Rademacher, are in the same range as the calculations i made. As mentioned earlier, Mr Roberts gets much higher power requirements, due to the higher surcharge factor.
Title of Rademacher's article :
Reclaim power and geometry of bin interfaces in belt and apron feeders
Is it possible that Mr. A.W. Roberts made a mistake in his article, or am i overlooking something here? Does any1 have an email adress of Mr. A.W. Roberts, because i would like to contact him about it.
Tx in advance