Hi all, just getting started on the conceptual design for a diesel power plant for a remote mine. Total capacity will be about 16MW and it seems that this is generally accomplished with 9x2MW units or so (N+1). ...!
First, a couple of guesses:
Commercial power is not available - not even small amounts.
Winter time power failure could put the facility into equipment damaging, personnel endangering, freeze-up with-in a few hours.
The client will be majorly freaked out if the process does not run flat out 24/7.
If these are not true, cancel most of the rest of my reply.
1. 16 MW is non-trivial. Just buying the machines in the $2/Watt range. $32M + buildings + auxiliary equipment. The client has plenty of money to play with to get the engineering right. For example, is the 16MW number a peak number or a prime (continuous) number? Yes it matters.
2. Prime rated recips are maybe good for 40K hours. For eight gensets, the client will be rebuilding two each year - unless they are only good for 25K hours, then rebuilding three or four each year. Consider there will be two to four months each year where there will be one genset down for planned maintenance. What is the plan if one is under rebuild and another decides its time for a turbo to send its guts through the intake intercooler?
With nine gensets, and a requirement for eight operating at 100%, MTBF is getting short. Depending on the client process available turndown, they may want N+2.
2A. Maybe the mine doesn't have to run for a few months during the winter and that is when the rebuilds are done. Only power needed is to keep the heat and light on. If so that really helps.
3. Instead of recip diesels, consider gas turbines - maybe 3 each, 8MW. The bean counters will be looking at the installed capital cost. I personally believe the correct response is to look at the life cycle costs. The maintenance on nine recips is a killer. For TGs, one can swap out a compressor section in a week. Same for the hot section. And only one has to be done each year. Suggest the client look hard at any offered maintenance contract. I've seen a few where the capital cost was way low and the maintenance contract made up for all the profit and then some. Remember - look at the life cycle costs.
4. And they will also need a black start. Depending on the hotel load, this is a good application for a 2MW peak recip, battery start.
5. Consider the turn down. Comments were made concerning wet-stacking. With eight operating gensets that won't be a problem. As the loading goes down, shut off a genset.
With TGs, there are air permit concerns. Some have to be operated above 60% (or so) to make emissions. For example, with two 8MW operation at a minimum of 60%, that is 9.6MW - Oh oh, what if the load is 8.5MW. For this case, that's easy, parallel the 2MW DG, base loaded at 80% - let the TG swing.
6. For distribution, consider 13.8KV. Scatter 480V, 1KVA - 2KVA xfms, and 4KV - 6.6KV xfm for the motors. It really depends on the size of the process and size of the motors. I don't know much about mining machinery - could be I'm all wet here.
All this is pretty simplified, but still the stuff I'd be looking at. Highly recommend getting a copy of IEEE redbook, Std 141, Electrical Power Distribution for Industrial Plants. IEEE is not printing paper copies any more (my hard copy is a 1993) but they may be selling electronic. I'll look tomorrow and see what exactly is available.
This is a dream project - keep us informed.
Ice
