Getting our first generator

[RobWard]

We are building a new factory and want to get a back up generator.

This would run on natural gas, for various reasons.

I've no experience of generators, only what i can glean off the web.
I'm wondering what questions I should put to potential suppliers.

We need to have back up power in case of a mains outage, as, if power fails during some critical operations, our equipment will break, and we'll end up junking some very expensive products also.

We're also likely to be getting very close to our supply limit on occasions (220kVa) so I wondered what the consensus on load shaving was.

Sadly it seems, from reading manuacturers websites, that a gas turbine powered genny isn't really applicable here.
I rather fancied having a jet engine to play with. Shame.

Any thoughts, or suggestions would be very kind.

Regards,

Rob

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[TheBlacksmith]

You should put your needs/requirements out to reputable suppliers and let them use their expertise to suggest the best method. Sounds like you need an uninteruptible power supply if your processes cannot tolerate any interuptions; any emergency set will take 5-10 seconds minimum to start and put out electrical power. There are a number of schemes, but it would be best to let them present options. Tell them (1) best fuel sources - apparently natural gas for you, (2) Essential loads, probably less than full operations load, but they will suggest some margin for future growth, (3) Anticipated duration of outages (see power company) (4) if there are loads that cannot be interrupted and their power draw, (5) Anticipated peak shaving loads, frequecny and duration of peak shaving.

Blacksmith

 

[tommom]

1) what is your load in KW/KVA?
2) What is your acceptable power interruption interval - milliseconds, or 5-10 seconds, 30 minutes?

You might need to consider a UPS if your power can only be interrupted for milliseconds, or fraction of a second. For 5-10 seconds, you probably could use a gas (expensive) or diesel engine with a belly tank.

Peak shaving makes sense if you get hit with a substantial penalty for exceeding a certain KW 15 or 30 minute demand.

Your load seems pretty small to be dealing with a turbine.

 

[BJC]

Make sure you understand the difference between emergency ( life safety) and standby. NAtural gas won't work for life safety systems as you can't store enough fuel on site to get you through an emergency.
Gas turbines may be fun but they take a long time to spin up and produce power.
Generators can be group unofficially as those:
1. That save peoples lives ( ie get them out of the buidling and provide essential services while doing so).
2. Power expensive processes or equipment
3. Run the whole place when the utility goes off line.
In addition fire protection fits in between 1 and 2.

 

[dpc]

Peak shaving is a difficult proposition because there is no margin for error. Depending on how the utility bills you for peak demand, having the generator fail to run when needed for even a few minutes can negate any peak shaving savings for the month or even an entire year.

I've never seen a peak shaving system based on engine-generators that actually saved any money. Also, this would require (I assume)that you would operate in parallel with the utility. This adds quite a bit of complexity and cost to the generator system.

I agree with BJC - if this is a legally required standby or emergency power system (doesn't sound as though it is), natural gas is very problematic in terms of satisfying legal requirements.

 

[RobWard]

Thank you chaps (or indeed chapesses; I haven't checked)

I'm going to call a few suppliers, but from experience, different people tell you different things, which makes it hard to sort the wheat from the chaff.

This isn't a safety issue. If the machines stop the resins will set up and block them which will cost a lot in both money and time to put right. And a part worth £12000 could be scrapped, which is a lot for a small company like us to swallow.
I'm wondering if they need a UPS as well as a generator, but I've only ever dealt with compute sized UPSs in the past so I'll have to do some research.

Our electricity supplier just informed us that our bill will be going up by 60% if we didn't sign a new 2 year agreement in 2 hours, else it would go up an extra 100% on top of that.
Sounded like blackmail so we didn't and have started shopping for other quotes, but what with that and the 20% increase in the price of natural gas we're looking at anything that can cut costs: hence the peak shaving.

Looking at our usage graphs we do have definite peaks, way above the baseline, so we might be able to so something, if not with peak shaving then maybe with some sort of load switching.

Unfortunately I'm rapidly running out of brainpower and everytime we've called a consultant in they've been awfully vague, spout the obvious, don't really help, and charge the earth.
I'll see what's available though.

By the law of averages, someone, somewhere, must work at a company where everything always runs smoothly, all outside events turn out for the best, and the processes are simple and enjoyable.

Thank heavens I'm here to balance things up.

It's nice to come here and get some feedback however.

So thank you all for your suggestions.

Kind regards, and seasons greetings.

Rob



"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[EEJaime]

RobWard,
If you ever run across that smooth running company, I would certainly appreciate it if you would drop me a note, I have been looking for them for a long time. Every time I think I'm close, that old rascal reality comes a-callin'.

It seems you are looking for a system to supplement the available utility service capacity to maintain your peak loads below a specific level. We have done this in several ways. One approach is to select critical loads which you cannot afford to lose and to identify large peak loads which kick you up over your desired load threshold. If these two loads are the same loads, that's even better. What we have done is to arrange our distribution system to isolate the critical loads from the normal plant loads and run these from the generator. Then using a manual or automatic transfer switch, enable these loads to be transfered to the utility bus when load capacity allows. Conversely, if you are running from the utility and have a power failure or other service interruption, the generators can be started and the critical loads can be transferred to the generator side. If the large loads that generate those peak demands far above baseline are in fact different loads, perhaps non-critical loads, then those can be segregated onto a third priority branch and controlled based on overall system demand and peak load capacity. Another factor which needs to be considered is block loading. It sounds as if you are working with resins which are heated and must be maintained at temperature to retain pliability. If that is the case and the loads are those monstrous resistive loads which heat the cauldrons, then you need to be aware that the block loading characteristics of a NG fired generator may not be the best option. Diesel engine fired generators come up to speed and can accept up to a 50% of full load block within ten seconds. The resins should be able to withstand this short interruption. NG fired generators on the other hand tend to need to "ramp up" loading, taking somewhat longer. Exactly how long will depend on engine size, load size and characteristics, etc..., but can be fairly well modeled by engine sizing software available from Caterpiller, Cummins-Onan, Generac, Detroit Diesel, etc....

There are numerous operational alternatives to these types of systems, from full co-generation, utility paralleled systems to simpler transfer on demand systems and all manner of system in-between. Fueling costs, space availability, run-time requirements, etc..., also become important to the first cost of the system, it's payback period, and it's reliability and maintenance requirements. Depending on your schedule for implementation, I would recommend you find a consultant with experience with these systems and have him prepare a study outlining specific options. I am not sure of your location, but it seems there should be someone available just about anywhere.

Best of luck on your project.

 

[itsmoked]

If indeed you are spending money on converting High Entropy electricity into low Entropy heat.... You could in fact see considerable savings using Co-Gen. Use gas/diesel to make electricity and the engine waste heat, (which is at least 60%), for your plant/process heat requirements.

Whenever you can use a generator's waste heat you rapidly move into the realm of reasonably.

I call this the "water-heater-that-puts-out-waste-electricity".

 

[MacRae]

Quote: I call this the "water-heater-that-puts-out-waste-electricity".

-LMAO
I have never seen it put that way before.
But, what a great analogy!

Ian Rines
Palm Bay
Florida

 

[RobWard]

Hmmmm.
Sounds very intersting.
Hadn't really considered that before.
A quick google hasn't turned up much, mostly government info.

Any pointers on where I can look at some info on this idea, preferably UK based?

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[itsmoked]

Rob not sure I understand your specific question? Not sure if it was referring to my response or EEJaime's excellent summation.

Most large hospitals use Co-gen because of the immense amount of very hot water they require, mostly for laundry and kitchen operations. I read one co-gen report on a San Francisco hospital that helped them save more than $10k or was it $50k (faulty memory cell) per month! by shifting over to a WHTPOWE.

Any business that needs a lot of low grade heat can use CO-GEN to great effect. Canneries, hospitals, laundries, laundry-mats, tanneries, food processors, paper mills, cloth mills, well you get the point....

On the home front, I believe that not another straight gas water heater should be sold. There is no excuse for a hundred million water heaters taking high Entropy gas and converting it directly into low Entropy hot water.. (Gesh what crime against nature). But instead every water heater should be a generator, taking the high entropy gas and using it to make extremely high entropy electricity. This of course costs you a lot in efficiency creating low entropy heat, which can heat water for space heating and hot water needs. I just love the thought of every time I need hot water, a generator kicks on. Essentially a water-heater-putting-out-waste-electricity.

Something very much like:

http://www.whispertech.co.nz/main/acwhispergen/

Unfortunately they won't sell me one.. Because they are only in NZ.

 

[ScottyUK]

Rob,

UPS Systems down in Berkshire are a systems integrator who might be worth a call:

http://www.upssystems.uk.com/.

They have some technically clued up people who should be able to work through what you need based on your requirements and put together a concept design.

Cummins have some capable engineers and good products. We bought a 350kVA set with a fairly complex transfer and load control scheme, and the final result is good. Their DMC300 system is capable of much more than we are using at present, and would eat your job up. As a company they suffer from the lethargy which afflicts giant organisations, and they seem to have a hell of a staff turnover. We got through a few engineers on that last job! There is a real lack of cooperation between the Wellingborough and Manston sites - largely over internal trivia such as cost codes for remedial works etc - but from my perspective it was just damned annoying. Once you get through the layers of bureauocracy and actually speak to the engineers they are a decent enough organisation.

If you decide on a UPS, GE Digital Energy got our last big UPS supply contract and were also offering to integrate an FG Wilson generator into the package. Their SitePro and Signature ranges are nice units, and their pricing was competetive.

Caterpillar have some good products but the UK sales staff weren't exactly great at getting us a package together. Same goes for APC, the UPS supplier, except their sales & applications team were just plain lousy at providing us with a solution. I can only speak as I find 'em: perhaps I just got unlucky?


----------------------------------

Your body may be a temple. Mine is an amusement park...

 

[Railgrinder]

Most of the other responses are pretty much hitting the mark in regards to picking the right size generator and if you are better off with a UPS. What is more important to me is how you are going to control the system. A backup system is pretty much useless if somebody has to be there to get the system up and running. Also I have never seen an engine generator set that would be ready to take a heavy load in less than a minute. You can do it in less if you don’t care if you damage the engine by putting it under a heavy load before it is warm, but obviously this makes it risky to rely on it after a few times of hitting hard with a load when it is cold. Woodward controls makes a solid-state engine generator controller that can be configured to run in several different modes. It can take over and automatically start and put the generator on line in the event of a mains failure, and will detect when the main power is stable and automatically switch back to the power company. All parameters from start up to shut down are programmable. It can be configured to run all of the time and provide a portion of the load or it can be set to provide just enough power so that you are not drawing anything through the utility. This is useful because the generator is always available and there will not be any interruption in the event of a utility failure. Woodward is top of the line equipment, you won’t find a better system.

http://www.woodward.com

 

[davidbeach]

Railgrinder, properly installed standby units are never cold, the coolant being kept at about 90F/30C at all times when the unit is not running. Standby/emergency units go from 0 rpm to full load in 10 seconds or less all the time, look at hospitals and other critical facilities.

 

[fsmyth]

A lot of good suggestions. If you cannot stand even a brief
interruption (i.e., some processes difficult or having an
extended restart period), absolutely put them on electronic
backup power. Possibly add an external generator, if the
shutdown period exceeds the UPS hold-up. One generator can
supply multiple UPS systems, but the (re)wiring could get
hairy if the production line is long. Try Best(Powerware)
or Emerson(Liebert) for large on-line backup power systems.
<als>

 

[RobWard]

Thanks guys.
The machines could normally withstand a 30 second power outage.
During high cost casting operations we could have the generator running, as they can take up to 40 minutes to complete but mustn't have an interuption or they're goosed.

I've not had a chance to look at UPS's yet, but am intrigued by combined heat and power. We run various ovens at about 100 to 140 deg C, all electrically heated, so I don't know how feasible it may be.
There are various grants and tax breaks for using this technology, it would seem.
I need to speak to a consultant about this I think.
Consultants are provided free if you spend £50000 per year on energy.

We're looking at about £40000, so we'll probably have to pay....like I said, someone, somewhere, by the law of averages etc....

It would be nice to use combined heat and power for "green" reasons, but we have to be realistic, and as a very small company we can't afford to spend money for no return, so unless I can show a compelling finacial argument we will end up with a simple back up generator and some automatic switchgear.


Thank you all for your responses, I shall spend some more time phoning and Googling with all the information you have provided.

To all who celebrate it: have a very happy Christmas.


Rob


&quot;I love deadlines. I love the whooshing noise they make as they go past.&quot; Douglas Adams

 

[MacRae]

Echo on the Liebert UPS systems. We have had good luck with them. We have a system at work that does not take lightly to any power interruptions at all. We are running a 100KVA Liebert UPS with a 300KVA CAT diesel genset. The generator does pick up the load fairly quickly, ie 30-45 sec. As for the service from the supplier, I am in the US at a very high spending company. So, while they are more than happy to jump thrugh flaming hoops for us, I can't say if the UK vendors will be as helpful. I have had no experience with them.

Ian Rines
Harris Corporation
Palm Bay,FL

 

[EEJaime]

RobWard,

As all the knowledgable gentlemen have already indicated, there are numerous sources from which to obtain information, especially on the co-generation side of the equation. Be aware that if your plant has a direct use for the waste heat of the generators, harvested via heat exchangers, etc..., that would be ideal, however if no such load exists, we have seen systems where heat was used to run absorbtion chillers to produce chilled water, steam generators to feed humidification systems, steam sterilizers, heaters and warmers of all kinds, domestic hot water, space heating heat exchangers for HVAC systems, etc..., so there are numerous ways to utilize a large percentage of the total energy converted, bringing up your overall system efficiencies to very "Green" levels.

 

[bonzoboy]

RobWard

You've got a couple of good chaps in the UK to address these issues. Alstom (Siemens) chaps in Lincoln (small to medium size turbines). Rolls-Royce Chaps in Derby (make both gas turbines and diesel units). Centrax boys somewhere near Portsmouth(?).

You could get a fairly large Cat unit that could start in a few seconds, but those are used mostly for emergency applications. In building/campus applications, I'd recommend a gas turbine. Even Bank of America uses them for power interruptions. What is your start up time and your total MWe requirement? Also, do you need low pressure steam, high pressure steam, hot water, hot air, space conditioning? Assuming you are preparing for the UK's planned blackouts, your choice of equipment is determined by your ultimate needs.

 

[RobWard]

Well Happy New Year everyone.
Feeling refreshed?
Good!

Back to work and I've started contacting companies regarding power monitoring, as I suspect that we'll need to do that if we're going to do this thing properly.

The energy market is getting proper scary here in the UK.
It seems we're running out of fuel and they've only just noticed. Prices are rocketing and the government don't give a rat's *ss about the manufacturing industries.
Russia's current spat with the gas supplies isn't going to help.

Seriously I'm worried that this could all end up in us being priced out of business.

Being in plastics, all our raw materials are tied to oil prices and customers only want to see price cuts nowadays, and won't take a long term view.

If we were starting out today, we probably wouldn't go into manufacturing, at least, not in the UK.

What I need to do is look at maximising our use out of energy we purhase, and minimising the total amount we buy.

I shall try to contact some combined heat and power people today, though I have a horrible feeling that we're too small for most people to want to deal with. Just big enough that the energy prices are very painful, but below the threshold whereby the grants for energy efficiency help kick in.

I've looked at the usage data from last year and we seem to have quite a "peaky" consumption (ranging from 2 to 80 according to the figures from the supplier, who haven't given any units, but it can't be KW or kVa) so I'll have a look at whether peak shaving is feasible, but when it's all new to you, it can all be a bit daunting, and I've no-one here who can guide me.

Thank goodness for eng-tips or I'd be truly scuttled.





&quot;I love deadlines. I love the whooshing noise they make as they go past.&quot; Douglas Adams