Combustor Basics
In this video, we visited our good friends at HY-BON/EDI to help bring you the basics of combustors. In much of the videos, you’ll hear from Corey Haney. Corey designed HY-BON/EDI’s combustor from the ground up and is immensely knowledgeable about this topic. Since it’s hard to cram everything into one single video, we opted to create two videos. The first video discusses the purpose and function of a combustor, where they’re found, the two different types, and components of the system.
Be sure to watch both videos, but in case you’re pressed for time, check out the summary below or check out the materials posted below.
- Once a well has been drilled, completed, and is brought onto production, the hydrocarbons that are being brought to surface and produced through the wellhead are under high pressure. The wellstream goes into a separator where the liquids will be separated out from the gasses. This is still done under relatively high pressures. Once the liquids are then sent to storage tanks on site, the light hydrocarbons trapped within the liquids (typically oil or condensate), have a tendency to come out of solution. The tanks can only be kept at a few OUNCES of pressure.
- We can either try and recover these vapors or destruct them. That will come down to what is most economical for a company to do, along with whatever the state mandates. If a company wants to recover the vapors, they’ll use compressors to compress the gasses back up to line pressure and sell them. If they just want to destroy them, they’ll use an open flare or an enclosed combustor.
- Which one is chosen will be based on anticipated flow rates, costs, regulations, etc. Typically flares are cheaper, but they also don’t commonly do as good of a job when you compare destruction efficiencies with that of an enclosed combustor. Enclosed combustors are much more precisely engineered for specific flow rates, compositions of gasses, and line pressure. It is common to see more combustors than flares in states that are more stringent such as PA, WV, OH, and CO. In states that are more strict, you might only be allowed to have an open flare on production facilities in a few particular cases. Flares are typically associated with cases that you need to burn a high volume of gas. They’re much cheaper but many special precautions must be given as they release a lot of radiant heat. You’ll typically see flares on locations where the well is being tested or unexpected gas needs released. Enclosed combustors “are typically used in applications where the variables, such as pressure, gas composition and flowrate are all known.” This produces a better destruction efficiency.
- There are two types of enclosed combustors – natural and mechanical draft. To get combustion, you need both fuel (which we’ve already established to come from the tanks) and you need air (oxygen). There are two primary ways in which you can get the air needed to combust the gasses- either through blowing air into the stack mechanically or by letting it occur naturally.
- Natural draft combustors are much more common in our industry due largely to economics. Electricity is rare on most production sites and blower maintenance could get costly over the years.
- Natural draft combustors operate by “the stack effect” which is the result of different air densities over the length of the stack. This imbalance caused by the heat from combustion, draws air into the stack.
- The components of a combustor system include the following:
- Emergency shut-down valve for the waste gas stream
- Inline flame arrestor for the waste stream gas
- High-temperature refractory
- Burner management system
- Continuous and reliable pilot system
- Combustor placement
- At least 70-80 feet from any possible point of release for combustable gasses.
- This will also depend on local regulations.
- Things to know when designing a combustor:
- Gas composition
- Heating values of molecules
- Line pressure to move gas to combustor
- Expected gas volume
- If a combustor is smoking, try checking the following:
- Restriction(s) in line(s)
- Air intakes
- Clogged orphices
- Cluster damage
- Presence of liquid(s)
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