How do you pump a solid?

November 14, 2013

In 1980 I spent an entertaining evening at a bed and breakfast in Stratford listening to my host describe pumps. He was an engineer for a company which manufactures pipeline equipment and the things he told me stuck in my mind.

The most interesting one had to be their use of regular jet engines to drive natural gas pipelines: as an experiment they put one into a shed beside the pipeline, burned natural gas from the stream in it, vented the exhaust through grates to the air above, and sat back to see how long the thing would last. The trick with a jet is that the flow of air through the turbine actually cools it, so a jet runs very well in a shed without a fancy cooling system. When the prototype didn’t wear out they put more and more turbine engines in place. They found over time that the service life for a gas turbine in a pumping station is much, much longer than for the same engine in a 737. My host told me that they hadn’t had one fail yet.

So this made sense: it’s easy to pump a gas/fluid which readily provides fuel to the engines which drive it. The gas logically would move easily through the pipe without high pressures or frequent pumping stations. So that’s the design for the west-to-east natural gas pipeline.

A pipeline is a magical metaphor for politicians to use: things go in one end and come out the other and nobody needs to understand how or why. But the image I see is a jet engine choking on tar and the 1/4″ pipe wall gradually sanded away to nothing by the flowing bitumen.

Bitumen starts out as a substance hard enough that it takes huge shovels to chisel it out of the ground. It’s abrasive. It certainly is going to be harder to pump than natural gas.

So, you say, they dilute the bitumen with natural gas in liquified form? So they mix the bitumen and the LNG together and pump like crazy and when it gets to the other end they refine the whole mess into petroleum products.

Trouble is, everything I could read on Wikipedia about liquifying natural gas products emphasizes how critical temperature and pressure are. What happens if something upsets this delicate suspension? Do we get the pipeline plugged with tar from Windsor to Cornwall?

I don’t have a dog in this particular fight, but I’d be very interested to know how Enbridge proposes to pull off this feat with a 1/4″ thick pipe stretched across the country.

I’d really like to know some answers here.


One Response to “How do you pump a solid?”

  1. Shiva Says:

    Not a petro engineer but 2 comments spring to mind:

    1. We probably don’t need to worry about the pipeline being sanded down by the bitumen. Friction means that the fluid nearest the pipe will move slowly (zero velocity at the boundary in the theoretical sense), so it won’t do much work on the pipe.

    2. Those jet engines that they use on pipelines are amazing. Some, like the GE LM1500, are direct copies of engines used in aircraft (J79 in that case). Others are engineered for industrial use specifically, and can run on a variety of fuels (gas/liquids). Here’s a great video flythrough of a 50,000HP Siemens model designed specifically for power generation:

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