Oil and Gas Operators lives are busy and dangerous. From driving hundreds of kilometers on ice-covered roads to checking wells and unthawing frozen lines, each day comes with its hazards. However, Operators wellbeing should not be put at risk, nor have to fear an impending threat to their safety, with an improperly functioning enclosed vapour combustor on-site. This is why technology providers such as Clear Rush Co., along with regulatory bodies such as the Alberta Energy Regulator, have designed strict regulations regarding how enclosed vapour combustors must be designed and operated in order to protect the industry’s workforce.
The regulation below is designed to prevent any vent gas on-site from autoignition either by the outer shell of the combustor, exhaust, or from the burner itself.
7.1.3 Design and Operating Parameters for Enclosed Combustors
1) Enclosed combustors must be designed and operated as follows:
a) Combustion process must be totally enclosed, except for the combustion air intake and the exhaust discharge.
b) There must be no visible flame.
c) All surfaces exposed to the atmosphere must
i) operate below the temperature that would ignite a flammable substance present in the surrounding area, or
ii) be shielded or blanketed in such a way to prevent a flammable substance present in the surrounding area from contacting the surface.
d) Exhaust gases must be below autoignition temperature of a flammable substance present in the surrounding area.
e) All intakes must be equipped with a flame arresting device.
Whenever we see “must” in a regulation we need to pay attention. This word is non-negotiable and is there for a reason. The above regulation pertains to the use of enclosed vapour combustors on a wellsite or facility where the units are placed a minimum of 10 meters from existing equipment on-site which may vent gas. Let us go through this regulation in more detail.
a) Combustion process must be totally enclosed, except for the combustion air intake and the exhaust discharge.
This means that where the actual combustion occurs must be completely enclosed and not open to atmosphere whereby vent gas could come into contact with the combustion process.
b) There must be no visible flame.
All flames must be enclosed and non-visible. Again, should any vent gas from an existing vent source on-site travel to the combustor, it must not be able to be lit or reach autoignition.
c) All surfaces exposed to the atmosphere must
operate below the temperature that would ignite a flammable substance present in the surrounding area, or
be shielded or blanketed in such a way to prevent a flammable substance present in the surrounding area from contacting the surface.
These subclauses ensure that the temperature of the combustor surfaces must remain below the autoignition temperature of the predominant gases which may be on-site. In most of the cases we have encountered the predominant gas is methane which has an autoignition temperature of 530 degrees Celsius. The skin temperature is monitored with a thermocouple and set to shut down the combustor should the skin temperatures reach a predetermined set point.
d) Exhaust gases must be below autoignition temperature of a flammable substance present in the surrounding area.
The exhaust gases coming from the top of the combustor, again, need to be below the autoignition temperature of gases which could be on-site. This exhaust is also monitored with a thermocouple set to a predetermined shutdown temperature.
e) All intakes must be equipped with a flame arresting device.
Finally, Clear Rush Co. holds this to be the most crucial clause. In order for proper combustion to occur we need to introduce air into the burner. This air is brought in by way of natural draft. Regulation states that this air intake must be equipped with a flame arresting device. Flame arrestors allow air and unfortunately vent gas on-site to be pulled through them. If the vent gas being pulled in is ignited by the burner the flame arrestor will cool the flame on its way back to the source and not allow it to move past or though the crimped ribbon cell.
If a combustor does not have air intake flame arrestors the combustor can potentially pull vent gas in from a nearby storage tank, leaking valve, fitting, or a tank truck which is leaking gas. This gas could potentially be ignited and travel back to that vent source resulting in a catastrophic incident. Always ask this question whenever you are considering an enclosed vapour combustor, “is it equipped with air intake flame arrestors?”
Visit our website to learn more: www.clearrushco.com/cubecombustor