Secondary digester

Secondary digester

Once the gases have been removed from the biomass in the primary digester, it is transferred to the secondary digester, where micro-organisms help to break down more of the biomass to gas. This maximises gas yield and prevents methane from being released into the atmosphere in subsequent uses of the residual biomass, for example as fertiliser.

How our biogas plants work

Feedstock

Feedstock is the biogas plant's fuel, and generally made up of animal manure, organic waste from the food processing industry, and agricultural crops.

Receiving tanks

The feedstock is delivered to the plant's receiving tanks, where it is stored until it is needed. These facilities are tailor-made to accommodate the specific types of feedstock used to fuel the biogas plant.

Feeding module

Xergi's unique feeding module FLEXFEED® pre-treats the biomass in order to optimise the breakdown process. It also ensures the module a correct and effective supply of biomass to the digester.

Primary digester

The biomass is mixed efficiently in the primary digester, GASMAX®, where the biogas is produced as a result of the digestion of the biomass under oxygen-free conditions. Wherever possible, a high process temperature is used to achieve the highest possible effect.

Secondary digester

Once the gases have been removed from the biomass in the primary digester, it is transferred to the secondary digester, where micro-organisms help to break down more of the biomass to gas. This maximises gas yield and prevents methane from being released into the atmosphere in subsequent uses of the residual biomass, for example as fertiliser.

Spreading on fields

The residual biomass can be used as a green fertiliser. Nutrients such as nitrogen and phosphorus are recirculated, thus reducing the need for synthetic fertiliser.

Gas upgrading

If the gas is to be distributed via the natural gas grid, the gas needs to be upgraded. In general this means that the CO2 is removed from the biogas, after which it achieves the same quality as natural gas.

Natural gas grid

By distribution via the natural gas grid, the biogas can be used as natural gas for e.g. combined heat and power production (CHP), industrial purposes or fuel for transport.

Gas cleaner

The biogas is cleaned of sulphur and any other possible components. This ensures optimal operations of the gas engine in the CHP unit.

Gas engine

The gas engine in the CHP unit transforms the biogas into energy in the form of heat and electricity.

scadaUser-friendly SCADA

An advanced process control system (link to User-friendly SCADA) controls and monitors the entire biogas process. It records processing data and provides feedback to the operator on the status of individual components as well as the entire system.

The control system is the 'brain' of the biogas plant. It is constantly gathering information on the biological process and providing Xergi with invaluable operational experience.

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