Young man checking gas compressor

Is the compressor station on your site functioning less than optimally? If so, you can rest assured, knowing you likely won’t require a whole new system. Many common troubles with natural gas compressors can be solved with a quick fix, clean or part replacement. 

Compression systems consist of extremely expensive equipment and technology. By keeping your site’s gas compressors in good condition, you’ll improve operation efficiency and reduce downtime so you can get the most out of your investment.

Below, we outline the basics of natural gas compression as well as how to perform compression repairs so you can ensure your operations run as smoothly and efficiently as possible.

How Gas Compressors Work

A natural gas compressor station is a vital component of a gas processing facility. Typically located every 60-100 km along a pipeline, compression stations ensure methane (natural gas) can move efficiently through pipelines to end-users. In addition, compressing cooled methane is the safest way to transport it.

The first step of natural gas compression is the scrubbing process. Scrubbing removes solid, liquid and gaseous impurities from the methane before it becomes pressurized.

The purified gas then travels through yard piping to the compression stations, where computers monitor and regulate the gas flow and increase its pressure by reducing its volume. Once full operational pressure is achieved, the natural gas is released into the pipeline.

Common Issues With Compression Systems

Like all processing systems with multiple moving parts, compression stations require regular maintenance and upkeep to run smoothly. However, sometimes basic servicing isn’t enough, and parts can fail. Below, we discuss common issues with methane compression systems to help you troubleshoot any problems you may be experiencing with your system.

Valve Failures

If your system has shut down unexpectedly, this may be due to a valve failure. Compressor stations have various safety systems in place to protect both workers and the public. These systems include emergency shutdown devices that prevent gas from leaking along with other dangerous situations.

Often, a shutdown is caused by a defective valve. Valve springs can become worn, preventing the valve from operating properly and leading to malfunctions in the compression system.

Fluid Leaks

Methane is a highly flammable gas but is virtually undetectable due to being colourless and odourless. Therefore, methane leaks are extremely hazardous and may trigger a shutdown.

Excessive Noise

Even under normal operating conditions, gas compressors are a significant source of industrial noise. However, if your system becomes more noisy than usual or exhibits unusual sounds, this may be a sign that something is critically wrong within the system.

The cause of excessive noise could be as simple as particle build-up on plates, which is easy to fix, or it may be due to a cracked damper plate.

Damper plates are designed to dampen the noise from vibrations in the system. Since these plates are under constant mechanical stress, they are prone to breaking and require frequent replacement.

Not Building Pressure

Properly pressurizing natural gas is crucial for efficient fluid flow. If you aren’t reaching the desired gas pressure, or if it is taking an excessive amount of time to achieve your operational pressure, you should check your valves and seals. Leaks within your system can lead to significant operational inefficiencies, leading to more money lost in the long run.

How to Repair a Natural Gas Compressor

So, can a faulty gas compressor be repaired? In most cases, repairs are simple and to be expected; otherwise, you may need to replace various parts and components. If problems with your gas compressor persist beyond simple repairs, then it may be time to call in an expert technician to assess your system and determine whether your devices are beyond repair or not.

This section outlines some common and simple repairs you can perform to ensure your compressor runs as smoothly as possible.

Replace Consumable Parts

Gaskets, belts, valve plates, and similar parts are prone to cracking, warping and breaking apart since they are subjected to continuous movement and vibrations. Ensure these components are replaced regularly and assess your system frequently to avoid extended downtime if they fail before expected.

Check for Corrosion

If you’re noticing corrosion or warping on any parts within your machine, this should be dealt with as swiftly as possible. In general, corrosion should be minimal; therefore, it may mean the wrong materials are being used in certain areas of the system. Consult with a specialist if you suspect there are unsuitable materials being used in your system.

Clean Pistons

Dirty pistons and valve plates can contribute to excessive noise in the system. Removing and cleaning these parts is generally a simple enough task to keep your machine running smoother for longer.

Check Valve Plates and Seals

Valve plates are notorious for causing problems in gas compressors. Warped or damaged valve plates can lead to leaks in the system as well as failures to reach the desired operational pressure. Ensure valve plates and seals are functioning optimally by inspecting them thoroughly whenever a leak or malfunction is suspected.

Contact a Professional

If a gas compressor repair appears too great for your team to handle, it’s best to contact a compressor maintenance professional to assess your system and potentially make extensive repairs. On the other hand, if your site’s equipment is old and inefficient, it may be best to purchase new parts and components for the best operational outcomes. 

At 24/7 compression, we have the equipment, experience and know-how to get your gas compression systems running as smoothly as possible. Contact us today to learn more about what we can offer.

There is a growing production and use of natural gas across North America. While this comes with many advantages, it also poses other threats. The environmental impact is at the top of the list of concerns, which calls for gas compression emission management.

Sources of Gas Compression Emissions in the Industrial Sector

Managing your gas compression starts with understanding your compression system. Notably, centrifugal compressors use wet gas seals or dry gas heals. The seals help prevent methane gas or process gas leakage at the points where the shafts and compressor casings meet.

The configuration of gas compressor systems utilizes packing technology to prevent leakage. The packing includes nose cup seals, gaskets, and a stuffing box. However, this is never wholly preventable. Thus, it calls for the need for specific changes in the design of compressors and their blowdown units.

Among the sources of methane and other greenhouse gas compression emissions include:

  1. The Counter Surface of the Stuffing Box: Over time, the counter surface of the stuffing box will degrade. The degradation is often due to unwanted deposits, corrosion, and minor indentations from previous gaskets. These irregularities will prevent the creation of a tight interface that can prevent leakage.
  2. Nose Gasket Overuse: Gaskets should plastically deform when put under clamping pressure. This characteristic ensures that gaskets can fill any irregularities between mating services. Overuse reduces the ability of gaskets to deform plastically. The result is that the gasket will fail to fill all the irregularities, leading to gas leakage.
  3. Misapplication of Gasket: Ideally, copper, aluminum, iron, and stainless steel are among the materials often used for manufacturing gaskets. Each material has unique clamping load, pressure, and process gas specifications. The material used should always be compatible with the application since misapplication could cause leakage.
  4. Cup-to-Cup Leakage: Finally, defects can cause gas compression emissions between two flat surfaces. Usually, this could be due to clamping force and size disparities.

How to Effectively Manage Compression Gas Emissions

Regardless of the source of leakage of liquid gases in the industrial sector, they are pretty manageable. Among the ways through which you can manage gas compression leakage include;

Reinjection into Turbine Inlets

Controlling carbon emissions from compression units can be expensive and demanding. But a more cost-effective method of burning fugitive gas emissions is to reroute the vents emanating from the dry gas seals into the inlet of your turbine.

Your worry could be about the flammability of the resulting air (oxygen) and methane mixture. Interestingly, this mixture falls below the flammability limits, which could often cause concern.

This emission management method does not require extensive maintenance. However, you may have to improve certain design aspects. The aim is to improve the mixing of intake air with the vented air to maintain low flammability. Of course, this is necessary both when the compressor is in operation and when it is not working.

Reciprocating Compressor Units

An electric reciprocating compressor that recompresses gas emissions is arguably the most widely used emission management method. This method reliably recovers and recaptures greenhouse gases leaked across seals and injects them back into the stream of process gas. Of course, this process happens at the discharge header or station suction.

Apart from injecting this fugitive gas into the process gas stream, it is also possible to directly inject it into the fuel inlet, the electrical generator, or the gas turbine. The fugitive gas is also usable as heating fuel. The size of the reciprocating compressor used in this method is dependent on the flow rate and volume of the emitted gases.

Recompression comes with two benefits. Firstly, it allows for the successful recapturing of emissions caused by station depressurization during planned shutdowns and maintenance activities. Again, recompression is pretty scalable, and a single unit is useable across multiple centrifugal compressors.

Frameless Thermal Oxidizer

Frameless thermal oxidizers will premix methane with auxiliary fuel and ambient air and pass it through a preheated ceramic media bed. The system effectively transfers heat to the gaseous mixture from the media bed.

The high temperature oxidizes the methane in the mixture into carbon dioxide and water. This method requires gas burners or electric heaters to preheat the ceramic media.

Thermal oxidizer units are vital in handling emissions resulting from compressor settle-outs and blowdowns. Besides, media beds used in this method are quite stable and resistant to fluctuations in temperatures. This feature enhances more reliable temperature controls.

Enclosed Vapour Combustion Units

Another interesting method of managing greenhouse emissions from compressor units is through enclosed vapour combustion units. Notably, vapour combustion units use enclosed stacks to collect and burn compression gases. The combustion in these systems happens at the bottom and is completely invisible.

These systems are pretty easy to set up and work flawlessly. They do not require any mechanical devices to help move fugitive gases into the stack inlet. Instead, they naturally draw in the heat generated from the combustive process.

Combustion stacks are can accommodate high temperatures to allow more fugitive gases to burn as they rise in the stacks. Enclosed vapour pressure combustion units work differently. Their burners are not ideal for high-pressure applications. Moreover, their enclosed designs could lead to too much flame on exposure to too much gas. Of course, very intense flames could damage the stuck insulation.

Supersonic Ejector Systems

Ejector systems are devices used for sucking in fugitive gas emissions from primary dry seals. This emission management mechanism does not feature any moving parts. Thus, it requires little or no maintenance.

In this method, the energy created by the motive fluids pressure will convert to velocity energy. The result is the creation of a low-pressure region which will easily capture emitted greenhouse gases. The captured air will mix with ambient air and move through the diffuser. At the diffuser, the air pressure increases while the velocity decreases to recompress the gas effectively.

You can then re-inject the recompressed methane-air mixture for various applications. It is useable in compressor inlets, heater inlets, and fuel system inlets. Unfortunately, you cannot use ejector systems to capture fugitive gas emissions from settle-out or blowdown emissions.

Double Opposed Gas Seals

Double opposed gas seals can also help you manage gas compression emissions. But unlike all the other methods discussed above, this method does not rely on recapturing fugitive gas emissions for combustion or reinjection into the system. Instead, it is a preventive method that ensures that there is no leakage altogether.

The method uses primary and secondary seals in a back-to-back arrangement. The mechanism then supplies inert gas such as nitrogen between the two seals. Any leakage will comprise nitrogen only, which is inert and harmless.

The reliability of this method depends on the consistent availability of sealed nitrogen gas. Again, it is impossible to rely on this method to address methane gas leakage from compressor blowdown.

Putting it All Together  

Gas companies across the supply chain are under intense pressure to reduce the emission of greenhouse gas into the environment. Of course, the pressure and concerns are pretty much in order. Natural gas compressor stations are responsible for a sizeable amount of the emissions. Focus now shifts from reducing emissions from combustion processes to cutting down gas compression emissions. The above technologies are very helpful.

There hasn't been a better time to upgrade, especially if you're looking to reduce your carbon footprint! 24/7 Compression is your solution. Contact us today, and we'll help you reduce your greenhouse emissions in no time!

Compressor stations are an integral part of the natural gas pipeline network that helps to reduce pressure and maintain flow in transporting natural gas from individual well sites. As natural gas moves through the pipeline, it is slowed by distance, friction and elevation differences. Compressor stations help these issues be resolved strategically placed within gathering or transportation pipelines so they can continue on their journey to market.

Understanding Natural Gas Compressor Stations

Compressor stations are an integral part of the natural gas pipeline network that helps to reduce pressure and maintain flow in transporting natural gas from individual well sites. As natural gas moves through the pipeline, it is slowed by distance, friction and elevation differences. Compressor stations help these issues be resolved strategically placed within gathering or transportation pipelines so they can continue on their journey to market.

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How Compressor Stations Work 

Natural gas enters a compressor station and is cleaned of liquids, solids, and particulates. The natural gas stream then goes through more piping to individual compressors, where computers regulate the number required to handle system requirements. On high-pressure occasions (like when you're cooking), several units can be operated in stages to provide needed pressure on an incremental basis ((Figure 1). When necessary, this process also works from the bottom-up, which provides for a gradual increase in flow at startup as opposed to outputting all available volume immediately upon demand

Natural gas needs to be cooled before leaving a compressor facility to cool down the stream. This happens by compressing it and dissipating heat at 100 PSI increments. Most compressor stations have aerial coolers for this task (after-coolers). The individual units generate heat which is then cooled with sealed radiators similar to those in an automobile engine - these are called 'before' coolers.

In wet gas areas, where the production of natural gas liquids (NGLs) is high, changes in pressure and temperature cause some of the NGLs to fall out. The NGLs that have fallen out are captured in tanks and trucked off-site for future use. It's called natural gasoline or drip gas since it is often used to blend with motor gasoline.

Most compressor stations are fueled by a portion of the natural gas flowing through them; however, there may be locations where all or just some units can only run using electricity primarily for environmental reasons or security reasons like location isolation from society on military bases, etc. Nevertheless, sites explicitly designed for electrical power generation will have different air emissions than those powered by conventional piston engines, which rely on combustion-driven pistons vs turbine-powered compressors driven electrically but emit sound at higher levels due to their design features geared towards acoustic containment rather than engine attenuation via mufflers like human ears do not hear well over long distances.

Stationary compressors are often housed in buildings to facilitate maintenance and sound management. But the newest units may be located one per building, as well. The walls of these buildings generally have insulation for better noise isolation and advanced fan technology that dampens the sound from inside and outside. In recent years, new construction projects have incorporated this design characteristic where local regulations require it; however, they vary significantly in their approaches when not required by law.

Compressor station yards for gathering lines are often larger than transmission line compressors due to multiple pipelines coming into the complex and, in some cases, equipment needed to filter out liquids from gas. Other components of a compressor complex include backup generators, metering equipment (to measure how much natural gas is passing through), and filtration systems that remove impurities like water droplets or dirt particles before it enters the pipeline system. In addition, there may be odorization facilities on-site; these sites will add mercaptan - also known as "sulphurous" chemicals- which provide distinctive sulphurous odours that warn us if there's a leak.

The Permitting and Regulatory Framework

Gathering pipelines are subject to permitting and regulation at the federal or provincial level, while interprovincial transmission systems come under either of these levels depending on the type of pipeline. A gathering line is any pipe that gathers gas from smaller lines in a region; an interstate transmission system is any line that carries gas across multiple provinces. The purpose, not size, defines whether it's a gathering or an intrastate transmission line.

Safety is an integral part of 24/7 Compression and Belair's operations. We are committed to protecting our employees, clients, property, the environment and the public by continually improving our HSE programs, policies and procedures to promote and maintain a culture of safety excellence. 

Compressor Stations within the Gathering System

Gathering lines are smaller diameter pipelines that take natural gas from the wellhead to a processing facility or interconnect with a more extensive pipeline. These gathering lines are regulated at the provincial level, and compressor stations in this system of pipes also fall under regulation. 

Natural gas in a gathering system can arrive at the compressor station with various pressures depending on the force of wells feeding it and how much gas travels from the wellhead to compressors. Regardless of these pressures, the natural gas needs to be regulated or compressed to enter an interstate transmission system at 800-1200 psi (pounds per square inch). Gathering systems have extensive facilities of 6-12 compressors because there are often significant requirements for compression within them. In addition, as more wells are drilled in an area, these buildings need to scale up as more demand for reduction exists. A typical permanent land requirement for a gathering system compressor is 5 acres, but they may exceed this if slopes exist or other factors are considered.

Compressor Stations within the Interstate Transmission System

A transmission pipeline is a wide-diameter, long-distance pipe that brings natural gas from the production area to market. These pipes can sometimes travel clear across the country. The Federal Energy Regulatory Commission has authority over the construction and operation of interprovincial pipelines.

Natural gas within the pipeline is usually pressurized at 800 to 1,200 psi. To ensure that gas flows optimally, it must be periodically compressed and pushed through the pipeline. However, friction and elevation differences slow the gas and reduce pressure, so compressor stations are typically placed 40-70 miles apart along the pipeline to boost pressure for optimal performance. A typical facility may consist of two compressor units (one operational one as backup) with a single building consisting of four acres or less of land required for a permanent location.

Natural gas within an interstate transmission system is generally already pressurized at 800-1200 PSI--to keep it flowing optimally, periodic compression boosts are needed every few miles on most pipelines stretching across states or countries; because they only offer increases in pressures, these facilities generally need much smaller footprints than gathering systems which require more energy-intensive processes like compression boosting; this means you can have compressors spaced about 70mi apart providing their localized benefits without disrupting other parts of your network; when using 50kW generators that recycle excess heat & power production into natural resources.

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