Natural gas skids, Diesel fuel skids 1

[rpedde01]

Happy new year,

I am working on a project to standardise the sizing of control skids for natural gas, diesel and heavy fuels oils.

i am looking for ideas for easy way of doing this. seprating them by flow requirements? pressure requriemnts?

any help is appreciated.

thanks

 

[dcasto]

what is a control skid? what would you accomplish by standardizing? how many standard skids would you sell? Why skid mount a control system?

 

[rpedde01]

Control skid is one which controls the fuel flow and fuel pressure.

i want to standardize the skids because we have different flow requirements for different size of burners.

any ideas?

 

[dcasto]

you want to standarize a flow control system for a 10,000% variable flow condition?

here is what you do, you get build skids with, 2", 3" , 4" ect pipe on them and put a 1 size smaller control vale in the pipe. Then you can do any range.

 

[rpedde01]

My flow requirements are 1000, 2000, 3000, 4000, 5000, 10000, 12500, 15000 kg/hr for desiel which varies from 5 to 75 GPM.

so i would like to design the fuel skids for diesel, heavy fuel oil later to gases also.

For liquid fuels the inlet pressures range from 145 to 150 psi and outlet pressure from 90 to 85 psi.

so the tricky part would be selecting the pipe sizes and then the control valves, pressure regulators, the safety shut of valve can be either the same size of one size smaller.

one more concern is the codes requirements for these skids when designed. ( FM and NFPA approval )

any suggestions to go about easily .

 

[jmw]

This is one of those "how long is a piece of string?" questions to which there are no easy answers.

There are perhaps 10-12 major companies that specialise in providing these skids.

The main criteria is usually capital cost and it is a competitive market where margins often aren't that great which takes some of the flexibility away from you.

Many of the companies who build these skids can supply at very competitive prices because they build significant numbers of them.
They (hope to) make money on service and maintenance over the life of the skid).
This is as it has to be because buyers worry about capital costs when buying the things and not about operating costs. That comes later, once they have them on site and in use. In a repeat order business, sooner or later you may think you will have to deliver economies on both capital costs and operating cost, or a demonstrated balance between them but in reality, capital costs often dominate purchasing decisions.

You need to find just the right balance and it isn't simply about size but also about quality or suitability.

All too often clients are penny wise and pound foolish (or is it "Look after the pennies and the punds will look after themselves"?).
When building a new supertanker, costing millions, they will not hesitate to invest a significant amount of time trying to scam the supplier out of another 20% from a piece of kit that costs $5-6,000 and then pay 50% more in operating costs.

For HFO skids the capital costs dictate the choice of flow meters used. These often prove troublesome and expensive to operate but the capital cost of a better flowmeter, one that would probably deliver minimal in service costs and superior on-stream factors is a tough sell.
Much as you might want to specify a rotor type meter the client may only want to pay for a sliding vane meter.

The heavy fuel oil skids will also have viscometers for fuel heater control. These are a one size fits all but they pay OEM prices for components which can be as advantageous as 1/3 the unit prices.
This is fine with a one size fits all item but when you get to the flow sensitive items, you can't simply standardise on one size because what happens is that the smaller skids for which it is over sized become uncompetitive.

But where these skids have a lot of components that are very sensitive to flow capacity such as the flow meters, heat exchangers, pumps, control valves etc., standardising is a tricky problem.
Some of these are low cost items and can be sized for the application because the numbers game doesn't deliver enough advantage from standardising. Others you may have to adopt a degree of standardisation simply to make the numbers game work for you.

So, for a given market share or number of systems supplied, standardising makes sense when the compromise is that you cover the eight different flow ranges you mention with, say, 3 or 4 different skids, if by so doing you can win on the supplier discounts on bulk orders for common components and can sell the end product.
If you supply enough of these skids then that 3 or 4 skids can become 8 different standard skids because each skid is more cost competitive for its specific application than a "standardised" skid that can serve two applications - once you get the numbers right.

And that is part of the problem, it is a numbers game.

But in any event, this is often a thankless task because you have to find a path between two competing ideologies... manufacturing and purchasing who want to produce a "one size fits all" solution so they can keep inventory down, minimise drawings and documentation preparation, and where purchasing can pressure suppliers for better prices (often in return for purchase contracts that agree to take a minimum number of units per year and take them in reasonable size batches at regular intervals).

Oh, and of course the clients, each of whom wants something special.

A good fit is where you are able to homogenise the hundreds of idealised individual schemes into a minimal set of standard solutions where the client will compromise his needs for the price advantage he gets by accepting a standard package.

How good a fit you achieve is only revealed when he buys from you and not your competitor.

So the question you ask is one that depends on a very wide range of factors, not least how effective your purchasing department is, how good your sales team is, how many you make, how flexible your client base is and how good the competition is.

The problem for the design engineer is to try and bring all these factors together in a reasonable way and satisfy his various "customers" and the design engineer's customers are not just the client who buys the skid but internal customers such as purchasing and manufacturing.

You will have to allow others to share decisions about which manufacturer to use for a meter or pump because they can get a better deal with one manufacturer and yes, they may be trade offs in operating costs, reliability and so on but that is the reality. It is more of a reality in one market segment than in another.

It isn't just an engineering solution but one which depends on how good a team there is working with you in each of their different skills.

This may mean, should mean, that you need to run up a few different options and then discuss with the other "clients". You need the input from the different players on your team.

This will be a balancing act where what works for you and your team will be a quite different solution to that which will work for one of your competitors.

That isn't necessarily a bad thing, it means that while you may lose the sale to one client because your solution is not so good as the competitors, you will win with another client where you and your competitors offer the same things but your solutions are seen as a better fit with their expectations.

What is sad is when your solution is rejected by all the clients or by too many of them, upsetting your projected sales or the sales split between sizes and thus messing up all those carefully worked out purchasing deals.


JMW

http://www.ViscoAnalyser.com

 

[rpedde01]

Thanks JMW for the suggestions. But we are one of Big companies and we have to standardise the fuel skids for cost and time reasons. I will eventually be sent out for fabrication to one of the manufacturers, but we would like to have our design.

If we have standardized fuel skids from which we can select, it be a lot of time saving for us for different capacities.

I like the idea which was posted by dcasto of making skids of 1" , 2" 3"... and so on till the maximum capacity.

i have start working on sizing to account for pressure losses and friction losses.

 

[jmw]

rpedde01,
I guess I may have misunderstood something here.
I assumed that what you were attempting was to take an existing product range and reduce it to a few standards.
If you are wanting to get away from custom designing each and every skid, then that is different.

Of course, a natural progression would be to go from custom designs to producing a range of standard designs that between them cover the whole range of process conditions you are likely to see.

What you then may need is a basic skid with "options".
You can add features and facilities as "modules" i.e. a standard add on cost (and watch the variances).

In that case, yes, you try and break down the range into managable bites, maybe cover those eight different duties with three or four different standard skids.
Just have to be careful that a standard skid doesn't get over priced for the bottom end application.

What I was thinking was that you maybe had a range of skids and there was an initiative to "rationalise" i.e. an internal requirement to reduce costs or improve margins. Always risky.

What clients expect is to see more and more features and lower prices year on year and that is not necessarily unrealistic.
So if what you are doing is moving from a custom design to a design where you have a standard layout and you just drop in the appropriate size meter, valve etc. then you should be able to deliver on this.

If you are moving from a range of "standard" skids where you are expected to cut some costs by reducing the number of standards, I'd be very careful unless it is a market lead initiative.

But in either case, if you are one of the big players then I'd have thought the most authoritative answers would be from some one like yourself.

In that case, one of the best approaches is to benchmark your competitors.
What are they doing?
Why?
Is it working for them?

The most significant thing to look for are where they change their product offering.
Change is always resisted - if it ain't broke, don't fix it so no change doesn't tell you anything useful but any change in their offering is always informative.

If you are doing something your competitors are not, are you right and they wrong? You need market intelligence to answer that one.

Two main causes of change are:
1) Market led; delivering a better deal to the clients. If you get it right and get there first, you should be on a winner.

2) Internal drive; cost cutting and rationalisation.
Often the imperative is to reduce costs or improve margins. OK, in an product you are always looking to find better and more efficient ways to deliver a better product at a better price and with better margins.
And some things you can standardise quite happily and purchasing can then do their thing and negotiate a better deal.
BUT if "the market is tight" (and the shareholders nervous) its a fair bet that what you will deliver is less choice at the same prices and that may prove to be a bad move.

It's very easy to make the product less saleable.

So you sell less and turnover drops, overheads have to be spread more thickly so margins drop and the next thing management want to push the prices up to restore profitability and turnover.
But that further depresses sales and before you know it they're into head count reductions, longer hours for the same money, and more meetings to take people away from doing all that extra work.

So, if you have been building custom systems, you need to sort out the best layout and the most common features to include as standard features.

Be careful.
It might be easy to say "we only do a few of those 1" systems, and as there isn't much call for them we'll just offer a 2" system whenever we need to."
The reason why you only do a few 1" systems might be that there isn't much call for them. But it might be that someone else does it much better and you are about to make life easer for them.
If dropping the 1" system didn't see more 2" systems, just fewer systems over all because for 1" systems they go elsewhere (seen it happen).

I'd say also that if this is a life-changer you need solid market research to see just what the market wants and why or, to see how well what you want t do will go down in the market.
You need to see if what you are proposing to do is going to be a winner or a loser - before you commit to doing it.

It is harder to win customers than keep them and far harder to win them back again after you've lost them.




JMW

http://www.ViscoAnalyser.com