Gallery, Projects and General > How do I??

Pumping gas

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Darren:
Now that's a great idea, I was thinking something similar but hadn't quite thought it through completely as yet.

We can't use the normal LPG tanks fitted to cars as they only take about 20bar and we need 200 bar for CNG. Reason being that it has less energy by volume so we need more of it to get any decent mileage from a tank.

BTW, welding bottles are rated at 300 bar so we could use those and they come in reasonable sizes too.

I was thinking of two bottles, fill one while using the other. Really long trips carry both. But the time spent running a motor to fill will cost. So your idea has merit.
One thing, a big tank will not fill a small tank with enough gas worth having without using a high pressure pump to transfer it over. We need enough pressure to convert the gas into a liquid. I believe this happens at about 1,100 psi.

SPiN Racing:
What type of vehicle you gonna put it in?

If it was a small truck.. or a car with..... Room to be modified.... You could do something like a race team Pit Cart.
They simply have some 1" angle Iron welded onto a small boc frame to keep them from rolling around, and a buss bar with the bottles attached to it.
Then you go down and open the valves and the bar is pressurised. The bottles are stored low in the vehicle, and are surrounded with some angle iron to prevent impacts etc. from blowing a valve off.

If its a car like a S-10 Pickup.. or somethig with a frame.. Realistically you could sneak the bottles up between the frame rails on eather side of the driveshaft.
Granted if its a Pickup.. simply put them in the bed, and hook em up.
OH and to keep officer Law happy.. Paint them Blue and put a No2 sticker on them. :D

sbwhart:
I've got it in the back of my mind that the nuclear power industry use none mechanical pumps to move gas round, I think they work symilar to a steam injector on Locomotives:- flow through a cone increased velocity increase pressure, bit hazzey I know but may be worth further research.

Cheers
 :wave:
Stew

Paul Barker:
Hello i am a close friend of Darren though we live a 7 hr drive apart.
It is really my question. Darren and I band these things about sometimes our mad professor ideas come to nothing.

By trade
I am corgi registered gas fitter in the UK after Darren's leed I drive an LPG van for my work.

In my work I work with LPG and Methane which we call Natural gas.


Yes I had read the Bates article which is where I discovered that the pump he used was a diving bottle compressor, which seems to be a three stage opposed piston pump. Forgive me I am not a mechanical engineer and dislexic so might get some technical names incorrect.

Reading up on the use of methane in countries where it is in the domestic domain, 200 bar is the usual and I found an old 2002 advert for a domestic garage pump costing $2,000. But I thought that was rather expensive. It also seems that the cost of power to compress the methane is half as much again as the cost of the gas (which in the uk comes out of the meter at 21mbar and you would have to do your pumping at night (which is the practice anyway over 5 hours) because our domestic gas meters are barely sized sufficient to supply the modern appliances. Since our infrastructure was put in at a time people had a cooker and if you were lucky a gas fire running on gas extracted from coal at the electricity generating plants (known as "town gas"). These mains are cast iron and geting on for 100 years old, so the pressure of gas inside them is also very low perhaps on average 30 mbar.

It is quite conceivable that if you sucked gas from your supply at too great a rate you could suck the flame out of your neighbours cooker which has no flame supervision device, hence when you stop your pump and the neighbours supply is back to pressure his kitchen will be gassed up to the explosive ratio of 5 to 15%, in he comes to make his first cup of tea throws a switch and boomb there is a picture of a pile of rubble on your TV AM podcast.

So, there can be infrastructure reasons why this may never be made legal in some countries, our infrastructures for services  being possibly the oldest in the world, and our country being near enough bankrupt and the Victorian work ethic having become undervalued by the grab what you can from benefits mutation of the Bevin Welfare State.

Now that all our products are imported from China and the people with the knowledge are gathering in these forums because industry has spat them out, and the admisnistration of our supply industries is handled by people who have no on the tools experience, we are in a mess. I represent British Gas as a front line fitter geting down and dirty with the stuff but I am managed by people who wouldn't even know the specific gravity of methane or what other gases are contained within it, and why (to control the calorific value). They wouldn't know how to take the case off most domestic boilers (because thankfully the manufacturers make it tricky so that the unknowledgeable (like managers) can't kill themselves or anyone else.

When you get this class of people administering dictating and ordering in an industry you are in trouble. The trouble is inside organisations graduates of nothing useful create for themselves empires and other empires clone around them like in a bubble map and departments are renamed so that they can have more nothing useful degree'd managers etc etc. Disseminate to conquer the poor weighed down bloke on the tools! You wouldn't believe the amount of office numpties from all different departments I have to negotiate like obstacles in a maize to achieve what should be a straight forward objective. Great Britain? It died with Fred Dibnar.

Anyway big storage vessel slow 24hr pressurising of it, and balanced release into vehicle tank sounds great idea, vehicle tank would receive percentage fill big tank contains in quick time. but massive tank cost and still require 3 stage pump which is also massive cost relative to savings.

What are the savings? Well Darren and I differ a little on this but he thinks 50% I think methane off the top of your domestic supply hense at your lowest rate comes out about 1/3rd the price of autogas (Propane in the UK) Insidentally autogas is as cheap a form of Propane here as a 47kg bottled for the domestic market. So no savings to be found searching out other Propane sources.

The problem with Methane is the cost of compressing it to a liquid so that the storage vessel can be appropriate for the use and the mileage sufficient, particularly considering it has to get you to your destination and all the way home since you can never fill up elsewhere in a country where you are the only one doing it..

Paul Barker:
You will not understand this next bit but the Triodes Darren is using would bring tears to your eyes if you heard them.

In the Uk these were used in rf (radio frequency) heating more specifically diathermy which is what makes the roast pork smell in an operating theatre (I used to be a nurse).

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