DE20210190U1 - Biomass heating system has separate units for burner, heat exchange from flue gasses and condensing unit for removing steam - Google Patents

Abstract

A biomass heating system with an enhanced heating efficiency has separate units for the burner (1) heat exchangers and condensing unit. The combustion gasses are passed through an initial heat exchanger (15) to generate heat air (12) which is passed over the fuel input and back into the burner. The combustion gasses are also passed through a filter (5) and over two parallel heat exchangers (6, 7) via a flap valve (9) to heat either an air stream or an oil circuit (8). The gasses are finally passed through a condensing unit (15) to remove heat from water vapor in the gasses. Heated air from the condensing unit is ducted into the burner.

Description

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Biomass heating with condensing technology

Condensing technology is now the state of the art for gas and oil heating systems. The combustion gases in the heating system are cooled to such an extent that the water vapor contained in the combustion gases condenses, making it possible to use the evaporation heat contained in the water vapor. In this respect, the fuel utilization rate of such heating systems, which are also known as condensation heating systems, is higher than that of conventional heating systems.

There are currently no systems for using condensing technology in the traditional way for wood heating or biomass heating, although the high water vapor content in the flue gas means that considerable improvements in fuel efficiency can be expected. The reason for this lies mainly in the problem of the low return feed temperatures in the boiler and the high solids and possibly pollutant content of the flue gas.

The only technology known is a so-called high-temperature condensing boiler (BHF-Kulkwitz), in which the flue gases are washed with a high-temperature liquid, causing the water vapor to condense into this liquid. Various post-treatments are necessary for this.

The innovation according to the invention solves these problems and opens up the possibility of using the advantages of conventional condensing technology in wood and biomass firing systems. To this end, according to the invention, the firing part and the heating part are decoupled and the heat exchange from the flue gas does not take place in the transition to water but in air and/or thermal oil, so that the possibility of generating water vapor for electricity production is retained.

The complete condensation of the water vapor in the flue gas, which requires temperatures below 30 ⁰ C, is again carried out decoupled from the rest of the process. This decoupling of the three processes of firing, heat exchange and high-grade condensation of the water vapor has the advantage that any additional units can be integrated between these modules, such as flue gas filters, distillations for the condensate, etc.

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By working in multiple stages, it is also possible to clean the system while it is still in operation.

The separate condensation allows any desired further treatment of the condensate.

Furthermore, it should be noted that the innovation according to the invention is just as applicable to small systems with a power output of a few kW as it is to power plants.

It should also be noted that it may be advantageous to equip the system with additional flue gas air preheating in order to avoid condensation in the combustion area or to dry the fuel before combustion.

An embodiment is intended to illustrate the advantages of the inventive innovation.

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Figure 1: The operating principle of wood or biomass heating in condensing technology in a simplified representation

You can see the furnace (1) with the flue gas outlet (2), the supply air (3), the fuel supply (4) and the fuel preheating (16).

The flue gases pass through a preheating (14) of the supply air (12) into the flue gas filter (5) and from there into two separately operating heat exchangers (6,7) whose supply of flue gas is controlled by the flap (9).

In the heat exchangers (6,7) the thermal energy of the flue gas (2) is transferred either to air or thermal oil (8).

The flue gases (2) are then condensed to a high degree in the condensation (15). For this purpose, cold fresh air (13) is supplied, which is heated in the condensation (15) and then used as combustion air (3). In this case, it is possible to also feed parts (11) of the flue gas (2) emerging from the condensation (15) back into the combustion (1).
The condensate (10) is stirred and can be treated accordingly.

Claims (5)

1. Biomass heating system using condensing technology, characterized in that the furnace ( 1 ), the heat exchanger of the flue gas ( 6 , 7 ) and the condensation ( 15 ) are arranged in several different containers ( 1 , 6 , 7 , 15 ) with the proviso that there is a spatial separation between these containers ( 1 , 6 , 7 , 15 ), wherein preferably between the furnace ( 1 ) and the flue gas heat exchanger ( 6 , 7 ) there is also a separate exhaust gas preheater ( 14 ) and a flue gas filter (S) and the flue gas heat exchangers ( 6 , 7 ) are designed at least twice. 2. Biomass heating according to protection claim 1), characterized in that the air flow ( 12 ) from the flue gas air preheating ( 14 ) can also serve to preheat the fuels ( 4 ). 3. Biomass heating according to protection claim 1), characterized in that the distribution of the exhaust gas flow ( 2 ) to the at least two flue gas heat exchangers ( 6 , 7 ) can be controlled by a flap ( 9 ). 4. Biomass heating according to claim 1), characterized in that the supply of combustion air ( 3 ) takes place via the heat exchanger of the condensation ( 15 ) with the proviso that the heat exchanger of the condensation ( 15 ) is supplied with cold air ( 13 ) for this purpose. 5. Biomass heating according to protection claim 1), characterized in that air or thermal oil, which are in circulation for this purpose, are used for the heat exchange of the flue gas ( 2 ) in the heat exchanger ( 6 , 7 ).