20 – 40 % more heat energy from the same amount of biomass

More thermal energy from biomass: a step forward in energy efficiency

Biomass heating systems are popular and have been in use for decades. Sophisticated technologies enable high levels of efficiency. However, the efficiency potential is far from exhausted.

StepsAhead, supplier of absorption heat pumps, and Schmid energy solutions have the common goal of further developing local and district heating networks beyond the current state of the art systems. The two companies decided to pool their expertise and sealed the deal in February 2024.

Active flue gas condensation with absorption heat pump for biomass heating plants – 20 – 40 % more thermal energy from the same amount of biomass

Wood-fired heating plants equipped with a flue gas condensation system can reduce their fuel consumption by utilizing the condensation heat in the flue gas.

The use of Schmid’s newly developed “Revolution adaptive” combustion control system is a major advantage here. It automatically regulates combustion and thus ensures a constantly low residual oxygen content in the flue gas. This increases the efficiency of the combustion process, raises the dew point temperature and thus allows an increase in heat recovery in the flue gas condensation system as well as a higher level of efficiency.

A further increase in heat recovery and therefore efficiency is made possible by the use of an absorption heat pump. This lowers the temperature of the flue gas condensation system below the return temperature of the heating network. The great advantage of an absorption heat pump is that it requires only a fraction of the electricity of a compression heat pump. The absorption heat pump uses hot water (≥ 105 °C ) from the flow of the biomass boiler as a drive.

The special highlight of the newly developed solutions from Schmid and StepsAhead

The absorption heat pump can be powered by a simple hot water boiler with a flow temperature of just 105 °C. This is a considerable simplification, as previously it was only possible to use it in combination with a hot water boiler (approx. 150 °C  supply temperature) that required testing and monitoring. The consistent optimization of the Schmid firing system and the absorption heat pump is paying off.

Video: advantages of an absorption heat pump

Retrofitting existing heating plants

Wood-fired heating plants that are already equipped with a flue gas condensation system can be retrofitted and benefit from the use of the new “Revolution adaptive” combustion control system and an absorption heat pump.

Functional principle of active flue gas condensation with absorption heat pump – effective and efficient

For flue gas condensation, the flue gas must be cooled below its dew point temperature. Depending on the fuel moisture and residual oxygen content in the flue gas, this temperature is approx. 45 – 60 °C | 113 – 140 °F. The further the flue gas can be cooled in the flue gas condensation system; the more condensation heat can be recovered.

In practice, the heat network return is often used to cool the flue gas condensation system. Its temperature is often in the range of 55 – 60 °C | 131 – 140 °F and therefore close to or above the dew point temperature. Under these conditions, the water vapor in the flue gas cannot be condensed or can only be condensed insufficiently, and the flue gas condensation system is limited in its performance or does not function at all.

The absorption heat pump is part of the active flue gas condensation system downstream of the boiler. This also consists of the flue gas condensation system with economizer (ECO). The absorption heat pump provides the flue gas condensation system with sufficient cold cooling water.

The low-temperature heat obtained from the exhaust gas is raised in temperature by the absorption heat pump and coupled into the network return together with the drive heat.

Video: how an absorption heat pump works

Cooperation with several advantages

 The collaboration between StepsAhead and Schmid energy solutions has made it possible to standardize concepts that were previously developed on a project-specific basis. As the engineering effort is significantly reduced, systems with absorption heat pumps can be implemented quicker and are also economically viable for heating plants with an output of approx. 1,000 kW or more.

Schmid energy solutions and StepsAhead are two innovative companies that take an unbiased view of energy technology and pursue future-oriented paths that make economic and ecological sense.

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