150811_Greg Hill_Westridge vapour capture

One of the most important elements of the expansion of shipping operations at Westridge Marine Terminal is an innovative new system to control emissions during ship loading. The system will ensure compliance with Metro Vancouver’s air quality objectives, despite more active terminal operations. We’re working voluntarily with our equipment supplier to be able to control non-regulated volatile organic compound (VOC) emissions, which can be contributors to ground-level ozone, or smog, to levels similar to those applicable in California.

Vapours are produced as oil is loaded into the double-hulled tankers that call at Westridge. As the levels of oil in the cargo tanks rise, the vapours are expelled from the tanks. Currently, these vapours are collected, piped to a nearby vapour combustion unit, or VCU, on the shore and destroyed.

At present, there is one loading berth at Westridge. The expansion plan calls for a total of three loading berths and proposes the application of alternative technology that would capture nearly all of the vapours and cycle the VOC vapours back into the tankers during loading.

Recently we spoke with Greg Hill, the Senior Director at Kinder Morgan Canada responsible for the facilities associated with the Expansion Project, to learn more about how the system would work.

How will loading emissions from as many as three ships be managed at the expanded Westridge Marine Terminal?

We expect to be loading one tanker about 43 per cent of the time, two tankers about 17 per cent of the time and three tankers about three per cent of the time. For the remaining 37 per cent of the time, no ships will be loading.

When we are loading one or two ships, emissions control will be handled by vapour recovery units or VRUs. The VRUs will capture approximately 99.9 per cent of VOC vapours, such as propane, butane, pentane, etc. These units will also remove the VOCs that are of the most interest to local regulators: benzene, toluene, ethylene and xylene with similar or greater efficiency.

All vapours captured by the VRUs will be liquefied by compression and cooling. They will be injected back into the crude oil streams being loaded into the ships.

When we are loading three ships, a vapour combustion unit or VCU similar to the one currently in operation at Westridge will also be used to destroy, rather than capture, the VOCs from the third ship.

 The reason for designing the system to primarily use VRUs is to limit combustion product emissions from the VCU, which include some greenhouse gases. Currently, the VCU operates for about 120 hours per month. Post expansion, we expect the new VCU, which will replace the existing one, to operate for less than 30 hours per month.

Odorous compounds within the vapour streams, such as hydrogen sulphide and mercaptans, will be handled in special removal vessels before the vapours enter the VRUs or the VCU. The hydrogen sulphide will be absorbed into the substance within these process vessels. The mercaptans will be converted within the vessels to compounds that can be more effectively captured in the VRUs.

Do other oil-shipping operations employ similar methods for managing emissions, including odours?

 Vapour recovery units are commonly used world-wide for ship loading, railcar loading and truck loading facilities. There are VRUs already in operation at refined products handling facilities in the Vancouver area. What makes the Trans Mountain design somewhat unique is the method of recycling the vapours after they are recovered. In most systems, recovered vapours are transferred to a process vessel to be directly absorbed into the commodity being loaded. This approach does not work well for heavier crude oil due to its low absorptive capacity, thus the requirement for liquefaction of the vapours before reinjection into the crude oil being loaded.

Which government agency regulates air emissions in Metro Vancouver?

The Expansion Project is regulated by the National Energy Board, or NEB, which does not identify specific air emissions criteria but expects project proponents to consider local criteria, if available, and criteria from other regulatory jurisdictions, if applicable. We have committed to the NEB that we will meet Metro Vancouver’s ambient air quality objectives, which are very stringent. We have also adopted some additional criteria from Alberta and other Canadian jurisdictions. Meeting these air quality objectives will significantly minimize emissions impacts to our neighbours.

In addition, Metro Vancouver and other jurisdictions in Canada do not regulate volatile organic compound (VOC) emissions as a whole, only some types of VOCs, such as benzene. The non-regulated emissions do not directly affect the health of the public and are present only in residual amounts that are unlikely to be noticeable locally. They can, however, contribute to the formation of ground-level ozone, which has the potential to impact air quality in the Lower Mainland. Working on our own initiative, with our technology provider John Zink Company, we are continuing to refine the design of the VRUs to achieve overall performance similar to systems in operation in California and other locations with stringent emission limits for VOCs. We will spend considerable capital to do this, perhaps $5 million more than what we might have to spend to meet the Metro Vancouver ambient air quality objectives.

Will people living in the vicinity of Westridge notice any odours?

 With the measures we are putting in place, we do not anticipate nuisance odours from our expanded operations. However, it is recognized that individuals can have dramatically different sensitivities to odours. As I mentioned previously, we will design the system so the emissions of odorous compounds do not exceed the Metro Vancouver ambient air quality objectives and those of the other jurisdictions we have selected.