For nearly a year, Xergi's new X-chopper® has treated 140 tonnes of deep litter a day at the French biogas plant Tiper Méthanisation. High uptime, low maintenance and fewer problems with stones are among the positive operating experiences with X-chopper®, which is also operating at Vegger Biogas in North Jutland.
With continuous production for nearly one year, X-chopper® - Xergi's technology for pre-treatment of deep litter, and other difficult biomasses - has now really started to prove its worth in practice.
"X-chopper® has been in operation at the Tiper plant at full capacity 24/7 and the results are very satisfactory. X-chopper® replaced two hammer mills that we previously used to pre-treat deep litter at the Tiper plant and the benefits are very clear. In the past, many large stones got into the FLEXFEED® modules, from which the biomass is pumped into the digester. This caused many problems with blocked and damaged pumps. We are not experiencing these problems anymore," explains engineer Henrik Kjeldgaard Hansen, who has been responsible for Xergi's development of X-chopper®.
Deep litter is a mixture of straw and manure. When mucking out the stables - for example with a small stable machine - small building pieces and detached stones from stable floors often end up in the deep litter, and stones are undesirable in biogas plants, where the biomass is pumped in pipes and tubes.
X chopper® works by steel chains rotating in a container. The chains crush grasses and other solid feedstocks, but also stone.
One tonne of stone a week
Stone traps are built into the FLEXFEED® feeding modules, where the effect of X-chopper® is clearly seen.
"On average, every week we remove one tonne of stone, which is separated out into the FLEXFEED® module's stone traps. Where the stones were previously fist-sized stones that wandered around in our system, they now look like granite chippings, because X-chopper® crushes them," explains Henrik Kjeldgaard Hansen.
Despite the hard work, X-chopper® functions with very little maintenance.
"It has a very high uptime. There is no daily maintenance in the form of lubrication. The only maintenance is the replacement of the chains that get worn down. It takes a few minutes to change a set of chains, once you acquire the habit," he says.
At Vegger Biogas in North Jutland, X-chopper® has now been in commercial operation for nine months. It has handled 20 tonnes of deep litter a day, as this is the maximum amount the biogas plant can receive. Here the results have also been satisfactory.
No floating layer
"We developed X-chopper® to get an effective technology that can solve the problem that deep litter, straw and similar substances float on top of the other biomass in biogas digester tanks. In X-chopper® we have created a unique technology that gets deep litter to dive into the other biomass. This results in a reduced need for stirring in the digester and we quickly utilise the full gas potential of the deep litter, which has been the goal all along," says Henrik Kjeldgaard Hansen.