Adequate gas venting is key for many reasons. Read all about it below.
Reciprocating or rotary compressors are used extensively in the natural gas industry to transport natural gas from both production/processing sites to authorized customer distribution systems. Since these machines work almost 24/7, they must be taken off-line from time to time for maintenance, emergency shut-down testing, operational stand-by, etc.
However, a few things occur when compressors are taken off-line for these reasons. First, as soon as technicians shut down the compressor units, the high-pressure gas trapped within the compressors and linked piping between the isolation valves is vented to a flare or the atmosphere. In other words, there is a ‘blowdown,’ which sometimes releases methane into the atmosphere from several sources.
Nevertheless, the depressurized system may leak gas from improperly sealed or faulty unit isolation valves even after these blowdown emissions.
Flaring – or gas flaring to the uninitiated – involves gas combustion in open flames (with zero energy recovery) that burns with unflagging resolve at the top of flare stacks in many oil production sites.
But gas venting is almost entirely the opposite. Gas venting refers to the controlled discharge or release of unburned gases into the atmosphere. This is usually performed to maintain safe conditions during every phase of the treatment process.
What Happens During Gas Venting Operations
When gas venting operations are underway, volatile organic compounds as well as methane, gas impurities, carbon dioxide, water vapor, and Sulphur compounds are released. Venting usually occurs during multiple processes, including well maintenance and completion. Therefore, it is not uncommon to associate odors with gas venting processes.
In most cases, these vented gases could be burnt instead of dispersing them into the atmosphere.
Burning gases meant to be vented partially reduces their environmental impact as regards greenhouse gases. This is because these gases would rapidly be oxidized, resulting in the formation of carbon dioxide. The latter has a global warming potential up to 21 times lower than methane.
Gas Venting Regulations That Companies Always Adhere to
The primary purpose of adequate gas venting using natural gas compressors is to conserve resources and protect the environment and the public. This is why most companies consider the following before undertaking any gas flaring or venting activity:
- Are there residents that would be directly affected by health or environmental concerns?
- Are there any residents in the area?
- What are the economic alternatives to flaring gases? Etc.
Companies are also expected to notify the public before planning venting operations. They must also manage all waste gases while reporting how much gas was vented or flared on a regular basis.
The firms must also respond to concerns or questions the public raises regarding venting or gas flaring. They must elaborate on the costs associated with venting and gas flaring activities.
What You Need to Know About Natural Gas Compressors
Natural gas compressors are electrical or mechanical devices whose primary function is to minimize the volume of natural gas by boosting the pressure of the said gas.
This operation is performed for 2 significant reasons:
- First, to reduce the volume of the natural gas so that larger quantities can be easily stored in bottles or tanks for transport or storage.
- To use the attendant volume reduction and pressurization in order to transport natural gas via pipelines for effective and efficient distribution over large areas. This includes distribution to customers or pipeline transportation.
At times, impurities – e.g., particulates and moisture – are present in the natural gas. This is why it is essential to filter and process the natural gas before permitting it to enter the compressor.
The Designs of Natural Gas Compressors
The mechanical and physical means of gas compressors vary, depending on their specific applications. However, the positive displacement reciprocating compressor design is one of the most popular designs.
The reciprocating compressor is composed of a series of pistons that looks like a vehicle engine’s cylinder. Natural gas is drawn into the enclosed cylinder space, and the piston’s mechanical action compresses the gas.
The natural gas is then released from the cylinder and into a pipe for swift transportation or a storage container.
The dynamic natural gas compressor is another well-known design that employs rotating vanes – over reciprocating pistons – in order to reduce gas volume and boost pressure.
Maintaining Natural Gas Compressors
Properly maintaining seals between the outside atmosphere and the seals between the compression area is one of the vital considerations of natural gas compressors.
The EPA (Environmental Protection Agency) refers to natural gas leakage as VOC (Volatile Organic Compound) emission. This is why federal regulations mandate proper tracking of methane and natural gas emissions from natural gas compressors within pipeline compressor stations.
It is not uncommon for seals in rotating machines to deteriorate over time due to constant use. Therefore, they require stringent monitoring as well as maintenance programs to help prevent the unexpected release of volatile organic gases from a leaking compressor.
Besides tracking and reporting vital requirements to the Environmental Protection Agency as well as numerous state and federal state utility groups, some federal rule initiatives have stipulated a few recommendations for minimizing emissions from natural gas compressors.
This is via the combination of improved cover design, seal installation, and venting systems to reduce compressor leakage emission by up to 95 percent.
It is no longer news that the United States relies heavily on high-capacity compressed natural gas storage as well as seamless delivery systems. This makes natural gas compressors integral components of hundreds of thousands of distribution systems and pipelines.
For this reason, natural gas compressors are monitored closely for damage, component failure, and wear.
Conclusion
The importance of adequate gas venting with natural gas compressors cannot be overstated. Gas venting is highly essential as it helps maintain safe conditions during every phase of the entire treatment process.
Research is still ongoing regarding alternative means of venting gases as they significantly impact the environment. But before then, natural gas compressors are constantly monitored for component failure, damage, and wear. This minimizes downtime while ensuring a smooth delivery system that is crucial for electrical and heating needs.