34


MODERN MANNERS


VAPOUR CONTROL • AGEING EQUIPMENT AND CHANGING STANDARDS MEAN TERMINAL OPERATORS HAVE TO KEEP AN EYE ON THEIR SYSTEMS, SAYS ZEECO


THE CONTROL OF FUGITIVE vapour emissions during product transfer remains a vital component in reducing the environmental impact of hydrocarbon and petrochemical operations. However, a large number of vapour control systems (VCS) in use today have been in place for 20 years or more, predating some regulations that started to come into effect in the 1990s. Since the installation of these VCSs,


operating and environmental requirements have changed, demanding more from the


vapour recovery equipment. This has resulted in a need for system design evaluations, and in some cases system design upgrades. In particular, the introduction of ethanol


into the gasoline supply chain has had a major impact. Fuel ethanol now accounts for around 10 per cent of finished motor gasoline delivered to consumers. The ethanol content can impact the operation of existing VCSs, particularly those using liquid ring vacuum pumps. Crude oil loading has also become more


common at many terminals and presents very different operating requirements for systems designed around gasoline loading. Crude oil characteristics are also highly variable and there are issues associated with the hydrogen sulphide content in sour crudes. Another driver for retrofitting work


is a move within the US in particular for the replacement of older vapour combustion units (VCU) with a vapour


recovery unit (VRU), sometimes with the VCU retained as a back-up. VCS providers are also seeing increasing demand in the Middle East and Russia, with potential opportunities in South America and the Far East. Speaking at the International Liquid


Terminals Association (ILTA) operating conference in Houston this past May, Simon Shipley, business manager for vapour recovery systems at Zeeco Inc, discussed the various options available to facility operators.


NEED FOR CHANGE Not long ago, a VRU with an emissions capability of 35 mg/l would have sufficed in most cases. However, emission demands continue to tighten with emissions limits down to 7 mg/l and 5 mg/l becoming much more common. Germany and The Netherlands recently introduced emission requirements as low as 50 mg/Nm3


rules, with a standard of 35 mg/ Nm3


and Oman has the tightest .


The reasoning behind particular emission


requirements varies widely. However, in gasoline VCSs an optimum standard could generally be said to be 1 g/Nm3


, where


“optimum” is defined by the ratio of recovered product to power usage. In other words, when


HCB MONTHLY | SEPTEMBER 2016


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