Green energy production: Increasing the future service life of fermentation plants through "on-site" measurement technology.

Axpo Kompogas AG produces energy and bio fertilizers from organic waste in more the 75 fermentation plants around the world. In order to improve the service life of its biogas plants, the Swiss company has decided to use a measurement technology solution from HBM. But how can sensors be securely and permanently installed in the wet and aggressive environment of a fermenter? The solution was offered by a process that HBM developed for offshore applications in the open sea.

From the waste resource economy: This is the gold standard for sustainable success in an era of increasing environmental and efficiency awareness. An important role in this concept is played by fermentation plants that produce biogas - and therefore , usable energy - from organic waste such as leftover food or garden compost.

With more than 20 years experience in this sector and over 75 plants in operation around the world, the Swiss company Axpo Kompogas is one of the leading operators and project developments in this branch. Axpo Kompogas operates 16 fermentation plants itself in Switzerland. The company manages a further nine plants with partner companies. These plants fermented more than 184,000 tons of bio waste in total during 2010. The net power production amounted to 22 million kilowatt hours.

Continuously rotating paddles are used in the fermentation plants to circulate the biomass.

In order to optimize the service life of their plants and obtain detailed information about possible deformation of the paddles, Axpo Kompogas decided to install a comprehensive measurement technology monitoring solution from HBM in their fermentation plant in the Swiss town of Chavornay, in the canton of Waadt. The Axpo Kompogas engineers also hoped to obtain more in-depth knowledge about the various forces acting on the plant equipment.

The strain gauges applied directly to the stirrer paddles will detect loads, overloads and deformations. This means the measurement technology is really "on site" and directly where the action is. This allows previously implemented calculations and simulation to be verified, and to indicate and implement constructive improvements for future plants based on the actual occurring forces.

However, the ambient conditions in the fermenter pose a particular challenge for the installation of the strain gauges. The paddles, and therefore the measurement points for the strain gauges and relevant cables, are located directly in the biomass, a constantly wet and aggressive environment. This means: the measurement point and cable must be absolutely resistant against biomass and moisture.

Inner view of the fermenter with rotating paddles

Because of this difficult task, Axpo Kompogas decided on a complete HBM solution: Strain gauges, a measurement data aquisition system and evaluation software - together with the direct installation of the measurement technology on site by experienced HBM service technicians.

Strain gauges applied to paddle

The HBM experts installed the strain gauges directly to the stirrer paddles and ensured the measurement points were professionally and permanently protected by means of a special multiple seal. In this case, they used the HBM know-how, unique worldwide, acquired during the installation of strain gauges in wind energy offshore plants, where the measurement technology needed to be installed and appropriately sealed in locations up to 30 meters under seawater.

The "HBM SoMat eDAQlite" amplifier in use here, which is applied directly to the face of the shaft, can also display all its particular strengths. SoMat eDAQlite is not only small, it can also be used under extreme ambient conditions. The processed measured data is stored in eDAQlite and (if required) compressed, and can be read in the HBM evaluation software catman® on the PC when necessary via the Ethernet interface. The Axpo Kompogas technicians have access at all times to the measurement data with this monitoring solution.

HBM SoMat eDAQlite amplifier installed directly on the shaft of the fermenter

It was important for Axpo Kompogas to have HBM as a partner for the complete measurement technology solution. With this complete solution, Axpo Kompogas was able to put an operational measurement system into operation - with minimum training requirements and perfectly designed for the hard conditions of the fermenter. HBM took over the responsibility for the entire measurement chain project and ensured scheduled completion by the time the fermenter passed acceptance.

Security through early damage detection - an advantage not only for Axpo Kompogas. Such monitoring systems offer solid economic advantages in numerous applications. With this complete solution, HBM offers "turnkey" solutions, even down to complete installation on request for extreme application conditions.

Axpo Kompogas AG