Drive Location = "Secret Consultants Business"?
Just a thought with the lack of response, is this q covering the hallowed ground of "secret" consultant IP?
To further explain, the reason I asked it at all is that we have tendered to do a mine startup detailed feasibility and it involves several overland conveyors that may be slightly regenerative. Should we be successful in being awarded the job then we will get proper designs done by a recognised consultant such as Overland Conveyor Co. However the prep work by others on this mine is so deeply flawed that we have included a few suggestions to significantly rework the proposed configuration.
When preparing these conceptual ideas it would be handy if my "guesses" are going to be born out when the real job is done, and for things like where the head ends are going to be it is silly to say it should be at the tail end if in reality we are not at a compelling case to do so. Therefore I was merely seeking some real world guidance as to when / what criteria may apply to say that one must, should or shouldn't put the drive at the tail? I have an implied assumption that this decision is directly related to the nett gradient so was asking about that also. But its OK if I guess wrong as the ego soon gets over it and we get on about the real task. However some insight to the underlying considerations would be appreciated, thank you in advance to anyone that may care to offer it.......? ■
Re: Partial/Full Regenerative Nature Of Conveyor?
Not sure about the transitions you mentioned.
I propose to calculate outright, rather than rely on rules of thumb regarding grade (I have personally calculated conveyors which are only 2% grade which would run away!).
I use the following criteria:
1. Calculate "low", realistic, restive force.
2. Calculate "high", realistic, acceleration force.
If 2 > 1 the conveyor is regenerative.
The question is how do you deal with it / does it really matter?
The drive / brake could potentially be at either end - depending on your criteria (i.e. CAPEX, OPEX, safety etc).
I am an advocate to improve the likely hood of suitable outcomes during execution, the feasibility study should reflect the execution strategy, in this situation I propose you engage a consultant (who would in turn complete the detailed engineering) to provide this advice for you.
Regards,
Lyle ■
Partial/Full Regenerative Nature Of Conveyor
Mr. VinceS,
Your rules of thumb are approximately right but you would never make any decisions (especially where to locate the drive and take-up) based on these. What is required is a thorough analysis and the answers will be clear. At DSI, our ExConTec modelling program does this quickly, dynamically, displaying the power at each drive and the take-up movement in reaction to loading on and trailing off and discontinuities of flow. There is no rule-of-thumb substitution for the thorough analysis. At a particular 7-flight DSI installtion, 2-flights were elevating and head driven while the other 5-flights were regenerative and tail driven. Of the 5-downhill flights, the profile of the 5th was being continuously redefined. In the end it turned out to not be regenerative but nearly so. We were already committed to the tail drive arrangement (equipment was already delivered) so we drove through the take-up. This is definitely not recommended but with the correct sizing and compensative design this has worked out fine.
There is no substitute for thorough analysis and completely understanding your system's behaviour subject to all possible running conditions.
Joe Dos Santos ■
Partial/Full Regenerative Nature of Conveyor?
Determination of Partial / Full Regenerative Nature of a Conveyor?
G'day,
Just wrestling with expanding my understanding of what happens when conveyors "start" to become regenerative, and figure out exactly when that happens and what actions are prudent to take at what point. Obviously from a design viewpoint there are worst loading / start-up combinations and over-run / chute capacity / braking considerations which is fine, but I am finding sharp transitions in the formulae I have (derived from the Apex Handbook calculations, which has served me just fine over the years for reasonably simple conveyors). I haven't got to the bottom of that yet, but am wondering if there is an accepted relationship between grade and length where a conveyor becomes partially then fully regenerative? Apart from brake insttallation it is q's like for instance when would it be best to put the drive at the tail, or more to the point when WOULDN'T you put the drive at the head?
Elsewhere in this forum I see that 2.5% grade is regarded as a point where regeneration is possible and at 6% it is a certainty, but what / how should it be determined by and therefore the relevant protections applied? Is it the same for an overland conveyor which may go up hill and down dale but have a nett grade to the head end? I have been using an intuitive determination to call 1% grade partially regenerative and 4% fully regenerative, but that was just a guess and anyway I don't know when to put the drive at the tail, probably above 5% would be my guess. Is there any clear science re this? Thank you. ■