Online, one can find no end of advice on mixing systems for biogas digesters - often going into great detail about impeller designs, speeds and angles – but away from the office desk, speak to a plant manager or AD operator, and they will soon tell you that even the best mixing system in the world is not something that they want – inside the tank.
Yet around 15 years ago when the UK was falling over itself in the rush to create seemingly ‘easy’, lucrative biogas, and funding was often only possible for what was considered ‘proven technology’, numerous continental-style package plants were invested in; lock, stock – and mixers.
As with all equipment types, you get what you pay for. There are some extremely well-designed submersible mixers out there that will provide long-lasting service – but the feedstock in the United Kingdom was not automatically going to consist of manure and maize, so no surprise perhaps, that with lower grade mixers installed during the biogas goldrush, there were going to be some casualties.
A biological process does not take too kindly, of course, to the huge amount of downtime caused by taking the dome off of a...
Successful installation
