Fugitive emissions in general and methane emissions specifically shall be avoided as per the Industrial Emissions Directive and the “European Green Deal”.
This presentation discusses valve emissions and concepts to reduce emissions to zero.
Although worldwide standards to measure leakage on new valves, like ISO15848-1 and -2, exist for several decades the measurements on site still indicate high leakage rates. The BAT (Best Available Technique) indicates as first requirement avoidance of the sources.
Saying that, when determining hazardous area zoning calculations use emission rates of 45 tons of CO2 equivalent for valves in transmission systems. International organisations like the OGMP (Oil and Gas Methane Partnership) indicate that leakage from valves reaches 180 tons of CO2 equivalent for valves in compressor stations.
Valve emissions are caused by wear, tear and ageing of the valve stem packing and therefore cause an increase of emissions of the dynamic seals during the lifetime.
The emissions of the valve will be eliminated when the valve stem to atmosphere, the dynamic seals, are eliminated.
This can be achieved in 3 ways.
a) By applying bellow seals.
For valves above DN100-DN150 this becomes expensive, also while actuator sizes increase.
For rotary valves or high pressure valves bellows are not possible.
b) By integrating hydraulic (or pneumatic) actuators inside the valve.
The dynamic seals are now against the hydraulic fluid, leakage will result in methane in the hydraulic fluid. This solution requires a hydraulic supply and a dedicated hydraulic control unit thus increasing cost.
c) By integrating a servo electric actuator thus containing the fluid within static seals only.
This solution is tested and confirmed TRL7 by Gasunie, the Dutch gas network operator.
Perfect control, low cost and zero emission over the lifetime.
Preventing valve emissions is adamant in achieving your net-zero ambitions.