Herhof GmbH

LARA^®

schematic diagramm of the LARA exhaust
air purification plant (please click to enlarge)The exhaust air purification plant is a thermal-regenerative exhaust air purification process according to the 30th Federal Emission Control Ordinance (BimSchV). The filter efficiency for the reduction of odours of this system certainly exceeds 95%.

In the air preparation and purification plant - in short LARA^® - the hydrocarbons are oxidised to carbon dioxide and steam in a combustion chamber at a temperature of 850 °C and a duration of at least 2 seconds.
With this patented system, we are able to observe the strictest EC emission limits and can actually go considerably below them.

During the exhaust air preparation, extremely high heat recovery is attained, which reduces the overheads. The efficiency of the heat recovery amounts to 98 %, with the result that the actual energy requirement adds up to only 2 % of the actual heat output.

The purpose of exhaust air purification is:

• The complete degermination of the exhaust air as well as
• The reduction of odours by means of oxidation of all carbon-containing odour carriers

Biofilter

In comparison to Herhof MBS plants, Herhof composting plants are producing less exhaust air. For this reason, in most cases, the exhaust air can be sufficiently cleaned by means of biofilters with a multi-stage fixed-bed filter. The filter material consists of several organic components and one inorganic component that ensures a filter efficiency of at least 96 % for Herhof biowaste composting plants. The humid air of the composting process will be passed through an open biofilter. In doing so, the air will flow via a relief chamber into the distribution channels under the filter. It will then slowly be released to the outside by diffusing through the biologically active filter layer. By means of the biologically active filter medium that is inoculated with microorganisms, air that is contaminated with odours will be turned into harmless compounds, such as water and CO₂.

The filter material consists of the special peat moss with excellent structuring and serves as carrier material for the bacterial flora.

Due to its own supply of food for the bacteria, the biofilter plant is insensitive to any occurring operational interruptions.

An environmental-friendly process with:

• Low overheads
• Little maintenance
• Extremely low emissions
• High flexibility

schematic diagramm of biofilter mechanism

For more detailed information, you are welcome to contact us.

Dust removal

In addition to the thermal exhaust air purification, the entire, completely housed conveyor system as well as the box hall of a Herhof MBS plant is suction-cleaned at defined suction points. The dust-filled exhaust air is passed over the dust removal plant. The deposited dust is then pelletised and transferred for suitable utilisation. To some extent, the dust-free air will be recirculated as fresh air into the machine hall. Via an exhaust air stack, the remaining airflow will be discharged into the atmosphere.