Improved valve control can significantly reduce methane emissions

Introduction

The natural gas industry commonly uses pneumatic devices powered by pressurised natural gas as valve controllers and pressure regulators. However, these devices are one of the main sources of vented methane emissions inthe industry, with 51 billion1 cubicfeet released peryear in the production sector alone.

These levels can be reduced or even completely eliminated by replacing high bleed and low bleed devices by retrofitting existing natural gas pressure regulators. Reducing the number of components in a system and improvingmaintenance practices can also be profitable.

Data from the United States Environmental Protection Agency shows approximately 400,000 pneumatic devices are used in the production sector to control and monitor gas and liquid flows indehydrators and separators, temperature in dehydrator regenerators and pressure in flash tanks. Approximately 13,000 gas pneumatic devices are used in the processing sector for compressor and glycol dehydration control in gas gathering/boosterstations and isolation valves in processing plants. In the transmission sector an estimated 85,000 devices actuate isolation valves and regulate gas flow and pressure at compressor stations, pipelines and other storage facilities.

Electric actuators and motorised regulators offera number of benefitsto reduce methane emissions, even enabling the design of zero emissions systems.

It is normal for pneumatic devices to bleed some natural gas into the atmosphere and so they are a major source of methane emissions from the natural gas industry. The actual bleed rate or emissions level mostly depends on the device`s design. According to the Natural Gas STAR Program (an emissions reduction framework for partner companies with oil and gas operations in the US), a high bleed pneumatic device is any which bleeds more than 6 standard cubic feet per hour which equates to over 50 thousand cubic feet each year.