Sewage treatment, petroleum refining and gas handling companies

[Spectre of Pithecanthropus]

I work in El Segundo, where there is a petroleum refinery as well as a sewage treatment facility. I'v notice that there is also a good deal of business in handling liquified gases. Air Liquide and BOC Gases both seem to have facilities nearby, for I see their tanker trucks all the time. Now, if the gases they contained were petroleum or sewage related, like methane and propane. But I also see trucks carrying liquified carbon dioxied and nitrogen. Why nitrogen? Why carbon dioxide?

[gotpasswords]

Why are they trucking around liquid nitrogen and carbon dioxide?

LN2 has a number of medical uses, and CO₂ is what makes your Coke fizzy.

[flickster]

Nitrogen is used in chemical & petro-chemical plants as an inert gas.

[Jinx]

Originally Posted by flickster

Nitrogen is used in chemical & petro-chemical plants as an inert gas.

To elaborate, because nitrogen is an inert gas, it is a good resource to use to push liquids out of tanks, for one. First, a layer of nitrogen fills the empty space within a storage tank to maintain a desired pressure (desired for various reasons). This is known as "nitrogen padding" or just simply "padding". Second, when fluid from these tanks is desired to be pushed down a pipeline into other tanks downstream, a valve is opened to allow more nitrogen into the tank. It can only enter if its pressure is greater than the tank's pressure, and the greater pressure pushes the liquid out and downstream.

Last, nitrogen is frequently used to purge lines of residual liquid material during a maintenance shut-down, for one.

As for the CO2, it may be an additive to get the right end result. It could be an inexpensive way to make a weak acid when bubbled through water. Or, it could simply be used in the R&D labs to refill bottled CO2 tanks (like the tanks of helium that fill kids' balloons)
- Jinx

[Spectre of Pithecanthropus]

Originally Posted by Jinx

To elaborate, because nitrogen is an inert gas, it is a good resource to use to push liquids out of tanks, for one. First, a layer of nitrogen fills the empty space within a storage tank to maintain a desired pressure (desired for various reasons). This is known as "nitrogen padding" or just simply "padding". Second, when fluid from these tanks is desired to be pushed down a pipeline into other tanks downstream, a valve is opened to allow more nitrogen into the tank. It can only enter if its pressure is greater than the tank's pressure, and the greater pressure pushes the liquid out and downstream.

Last, nitrogen is frequently used to purge lines of residual liquid material during a maintenance shut-down, for one.
Jinx

Sorry for the bump, but I clean forgot about this thread, and then did a search on all my started threads, which I do, periodically.

So what you're suggesting is that the tanker trucks might well have been carting N2 to the refinery and not from it.

[flickster]

There is no MIGHT HAVE BEEN, they were transporting gasses, which are used in the production process to the facilities, not away from.

[Noone Really]

The carbon dioxide is almost certainly a refinery product. CO2 is a byproduct of the steam hydrocarbon reforming process used in most refineries to manufacture hydrogen. There are no refinery processes which require CO2 as a feedstock.

It is likely that the liquid nitrogen is being transported to the refinery for use as an inert gas as mentioned already. Most refineries would produce the base load nitrogen on site utilising technology such as pressure swing adsorption, using imported liquid nitrogen when demand is greater.

It is also possible though that the liquid nitrogen is a product. The most economical process for bulk liquid nitrogen manufacture is cryogenic. The only problem is that the these plants typically produce in excess of 200 tonnes/day and a typical refinery may require in the order of 20 tonnes/day for base load inerting of tanks etc. It is not unusual for a refinery to form a joint venture with a 3rd party gas company and install a nitrogen plant with excess product being sold. Another product of a cryogenic plant is liquid oxygen which is also used in some refineries.

[Unregistered Bull]

Carbon Dioxide and Nitrogen are used oil and gas well stimulation (energized fracs). Carbon Dioxide is also use in floods (injected into the oil producing formation) to increase production.

Carbon Dioxide besides being a byproducts in many processes also occurs naturally. I've worked in a liquefaction plant where we got gas off of CO2 wells that we liquefied for making dry ice, delivering to soda manufacters for fizz, and slaugther houses and food manufacturers for quick freezing. The wells that we got the CO2 from were from a major energy company. They were outside their gathering system (pipeline system). Those in their gathering system were sent around couple of hundred miles down a pipeline to an oilfield for injection.

The company that I worked for also bought CO2 from refineries and an ethanol plant.