Reducing Fugitive Emissions from Control Valves

As operators in the oil & gas industry, it is vitally important to optimize the performance of control valves to maximize efficiency and profitability while maintaining safety and reliability. Usually, during a turnaround or maintenance, control valves need to be replaced or upgraded to maximize efficiency and profitability. In the past century, there have been many technological advancements in medical science, artificial intelligence, autonomous flying vehicles, and more.

By Kyle Daniels, President & CEO, Clarke Valve

Globe Valves in the 21^st Century

The pressure from the government to prevent emissions from releasing into the atmosphere in the oil & gas industry is ever-increasing. As the requirements to stay within the regulatory limits for methane emissions become stricter, the demand for a valve that does not leak, requires no adjustments or maintenance on the packing and measures 2 parts-per-million, increases.

Attempting to achieve net zero opera­tions while utilizing globe control valves can cause setbacks to an entire organi­zation’s methane target dates. The con­ventional globe valve design was pat­ented at a time in which environmental protection efforts were not a top prior­ity, and the core of the original design has seen little change since its inception. Typically, these types of valves record a methane leakage rate of ~500 ppm, and the most common solution to reducing the leakage rate is to have maintenance personnel tighten the stem packing dur­ing inspection periods. This method only marginally reduces emissions and does require constant attention and mainte­nance visits, which is costly and inefficient.

New valves, such as the Dilating Disk™ Valve, are becoming a move viable solu­tion for upgrading relatively inefficient leaky, and high-maintenance globe valves in the field.

Rather than improving on existing de­signs, engineers have seen the benefits of engineering from the ground up. This clean sheet approach resulted in a long-overdue change in valve design that achieved the first-ever recorded methane leakage rate of 0 ppm in the field. It also provided a centralized flow path that great­ly reduces cavitation, precision flow con­trol capabilities, and a more compact and lightweight package than traditional globe valves. One of the critical elements that set new designs apart from traditional globe valve designs is its patented stem seal technology, a redesigned stack of spring-energized seals that prevent methane from escaping the valve and eliminates the need for field adjustments. This was a major factor in earning the valve its ISO 15848-1 and API 641 certifications with A-ratings, which have leakage rate stan­dards of 50ppm or less.

Valve Trend Data

Valve trend data is an important metric for end users and control valve manu­facturers. Valve trends are data points, based on electronic signals taken from the valve positioner and the control room, taken at regular time intervals. In this case, the end user is collecting valve position data points once a day. Although the valve cycles many times throughout the day, an end user can verify that the control valve is moving to the correct position through daily measurements. As noted in the data, the valve trends are a near-perfect match between the signal, which is the control room data point, and the valve position (actual), which is the valve positioner data point. This is what end users and valve manufacturers are looking for when reading valve trend data. The bet­ter the match between signal and posi­tion, the more accurate the valve, and the better the process is being managed by the control valve.

The reason a control valve has to change position so often can vary from process to process. Typically, the main reasons a control valve will change position is to precisely adjust the temperature, pres­sure, or flow rate of a process. Without the ability to precisely control these vari­ables, it would be impossible to produce high-quality, high-purity chemicals such as gasoline, natural gas, or even drink­ing water.

By following all applicable industry stan­dards for control valves and adhering to the most rigorous standards for quality, it is not only precision that is important, but also safety, reliability, and as always, zero emissions.

Case Study

The Dilating Disk Valve technology has been field-proven across various down­stream oil & gas applications. In February of 2020, five legacy globe control valves were replaced with DDVs in five differ­ent applications within the same refin­ery: raw oil, stabilized oil, water, natural gas, and amine. The goal of this project was to monitor the process control per­formance of the valves and to measure the fugitive emissions output so that the results could be compared to the valves that were replaced. Over the last two and a half years, all of these valves have mea­sured 0ppm, with zero adjustments and zero maintenance required.

This is why new solutions are becoming more and more desirable; they offer a plug-and-play, field-proven, and reliable replacement option for globe valves. The reimagined design brings operations into the 21st century and allows organizations to take control of methane emissions in the field. By committing to replacing legacy hardware with low emission 21st century technology, the oil & gas industry can make major strides in minimizing the emissions that leak from its facilities.

References:

1. https://www.linquip.com/blog/control-valves/
2. https://www.wermac.org/valves/valves_control-valves_principles-of-operation.html