Mixing it up
In many areas of fuel processing, blending and mixing are two of the most significant, yet basic operations.
For the simplest fuel blending, two or more components are combined and diffused by means of flow movements. This results in a uniform compound, the elements of which are in the smallest possible volume. The process of bringing two or more liquids together covers a range of technologies, including static in-line blenders, dynamic mixers, multi-stream blenders, top entry mixers, positive displacement meters and injection systems using multi-headed reciprocating positive displacement pumps.
All have their particular role to play both upstream and downstream of tanks and within the tanks themselves where it is often necessary to keep blended products in a stable condition. In many industries, continuous in-line blending is highly desirable as it is far more economic than batch blending and allows other processes downstream to be optimised. Where a range of products such as automotive fuels, toiletries and beverages are made up from a common base, in-line blending and injection systems enable fast switch-over from one product to another to meet demand.
In the case of the automotive fuels industry, multi-stream blending can be performed at the loading rack, thereby reducing dependence on multiple storage tanks. Blending technology gives companies greater flexibility, enabling customer-specific products to be produced on demand far more economically, even when taking into account the costs of investing in such systems.
Additive injection is of great importance within the fuels industry, where dyes and markers, anti-foaming agents, cold-flow enhancers and lubricity enhancers are essential ingredients. The same can be said for the offshore oil exploration and recovery sector, where chemical injection packages for adding biocides, oxygen scavengers and anti-foaming agents are a continuous requirement. However, the types of technologies used are very different.
Jon Denis of Netherlandsbased Enraf Fluid Technology says that in the fuels industry the whole concept is now about how companies differentiate their products or make them easier to handle and this involves adding various ingredients. ‘At one time, because of the small volumes of additive required it was easier to dose the additive in bulk storage,’ comments Jon Denis. ‘As additives became widespread, the need for flexibility drove additive dosing to the headers and load racks, which resulted in very small volumes of additive being required. Volumes of this proportion were difficult to mix and meter and it is this that has led to the development of new dosing techniques.’
