(It doesn't matter how "dirty" the gas is - it's going out the stack in flames and all BTUs are wasted....
2006-12-11 04:16:13 · 8 answers · asked by Anonymous in Environment
Hydrogen sulphide and sometimes carbon dioxide often have to be removed in amine treatment units for natural gas to meet sales specifications. Depending on the exact composition and amounts of this tail gas the modern preference would be to recover the sulphur in elemental form from this tail gas (in Claus units) and prevent emissions of polluting sulphur dioxide. Burning the tail gas in process heaters has never been an attractive option as hydrogen sulphide has a low calorific value and low flame speed making burner design to produce a stable flame difficult as well as producing highly corrosive combustion products.
2006-12-11 15:44:49 · answer #1 · answered by Robert A 5 · 0⤊ 0⤋
As you noted the refiners or in some cases at the well sight, they do burn of so called "sour gas" but the reason is to get rid of Hydrogen Sulphide gas. This is a very foul smelling and pushiness gas and by burning it the refineries remove these two problems. These reasons are also why they do not use on site as a BTU source. Once in a while the flame goes out and must be re-ignited quickly so a flair, plume is easier to light.
Another problem with this gas in higher concentrations actually shuts down your ability to smell it. So you could in theory be in it and not realize it, till it kills you.
2006-12-11 04:44:32 · answer #2 · answered by eudaemon 4 · 0⤊ 0⤋
Sulfur Dioxide is a criteria air pollutant. There are modeling and health effects reviews that must be done to permit any emission increases for SO2.
Flares are designed with height and velocity requirements for the output of these emissions to maximize dispersion and therefore minimize health effects. Heaters and Boilers will generally not meet the same dispersion characteristics as the flares. (IE, they just aren't normally as tall as the flare stack.)
Some refineries do use sour fuel gas to power heaters and boilers, but only after amine treatment in a sulfur recovery unit to reduce the amount of total sulfur in the gas to at least 99.8 percent of the original sulfur in the stream. However, often the volumes of this fuel gas is so large that in order to continue operations at a high rate, much of the gas is wasted by flaring, because there is no way to economically store this material.
2006-12-11 04:34:03 · answer #3 · answered by jimvalentinojr 6 · 0⤊ 0⤋
The gas that is burned off is kept to an absolute minimum as this is purely a safety device which in times of plant upset or emergency allows the operator to vent the gas to flare.
It would not be safe to vent unburnt gas because of the risk of vapour explosion.
The plant owners do not willingly waste their resources and this gas is a valuable source of heat energy.
2006-12-11 04:45:11 · answer #4 · answered by Barrie G 3 · 0⤊ 0⤋
I assume because there is no market for electricity in the area. If there was, I would expect them to do just as you say and use the heat to fire a boiler, since they are burning the gas anyway.
2006-12-11 07:36:35 · answer #5 · answered by campbelp2002 7 · 0⤊ 0⤋
The gas released is a safety pressure relief mechanism. They burn it so it does not fill the atmosphere with raw gases. Reusing it would only add more pressure to the system.
2006-12-11 04:26:36 · answer #6 · answered by Anonymous · 0⤊ 0⤋
If its sour gas it is deadly and they probably do not want to handle it so they burn it off.
2006-12-11 04:21:26 · answer #7 · answered by canoratrick 2 · 0⤊ 0⤋
because using them is not convenient.
Besides it requires more capital investment, and investment on technology ehich may not provide suitable returns.
2006-12-11 04:23:07 · answer #8 · answered by Som™ 6 · 0⤊ 0⤋