DE8703307U1 - Heating device with flue gas scrubber - Google Patents

Description

Dlpl.-Phys. LORENZ

This case file no. 43/3

Hubert Nuebel

To Wasserberg 3

4796 Salzkotten-Tudorf

Heating device with flue gas scrubber

^ Description

The invention relates to a heating device according to the preamble of claim 1.

A flue gas washing device is known from DE-PS 16 71 393, in which nozzles are arranged in a flow chamber, with which washing liquid is sprayed in the form of a water veil or mist, mainly at an angle against the direction of flue gas flow, which flows in countercurrent through the flue gas into a collecting device, from where the washing liquid is pumped back to the nozzles. The flue gas heat is lost as heat of evaporation, and the resulting steam must be discharged into the atmosphere by conveying air, which requires fan energy.

Furthermore, heat pump heating devices are known in which outside air and, in the case of increased heat demand, flue gases from a combustion plant act on a first heat exchanger which is connected as an evaporator of a coolant circuit,

which leads via a compressor and then via a condenser, which is a second heat exchanger through which a heating circuit of a hot water heating system flows. Due to the relatively low heat transfer between a gaseous medium, i.e. air or flue gas, the evaporator must be provided with large surfaces and exposed to intensive ventilation, which leads to a lot of noise, so that a given amount of heat is exchanged at a normal level of efficiency. Furthermore, for safety reasons, it is not permitted to expose the heat exchanger to flue gases that are above the critical evaporation temperature of the coolant in the cooling circuit, which is why these must always be mixed with a multiple amount of additional air, which reduces the efficiency because entropy is lost during the mixing process.

Furthermore, from DE-OS 31 45 302 a heating device with a flue gas washing device is known, in whose washing liquid a heat exchanger is arranged that cools it and is connected to a heating circuit on the other hand.

DE-OS 27 32 744 describes a heating device with a

f-, heating boiler with a connected heating circuit, with a smoke gas scrubber and with a heat pump, whose evaporator is cooled by the washing liquid and whose condenser is arranged thermally parallel to a heating heat exchanger in the heating circuit and which contains a return heat exchanger in the heating circuit, which on the other hand contains another evaporator that is connected upstream of the evaporator of the washing liquid cooler. The heat pump throughput must be dimensioned in such a way that the residual heat from the return of the heating circuit is passed through as the flue gas heat, and its pumping power must

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at low efficiency, it can be so high that the condenser ⁴ operates at the flow temperature of the heating circuit. The device also has a controllable outside air supply to the washing area, whereby heat can be extracted from the outside air by means of the washing liquid and fed to the evaporator of the heat pump system.

The purpose of this device is that pollutants in the circulating liquid are adsorbed from the flue gas by the washing process or, if the composition is suitable, chemically bound, and that condensing pollutants are also removed by cooling. In addition, the flue gas and condensation heat of the flue gas moisture are used. Due to the low washing liquid temperature, the vapor poison content in the exhaust gas is relatively low. In addition, this arrangement offers the possibility of being used as a heat pump heating device for extracting heat from the outside air.

The object of the invention is to improve a generic heating device so that it contains a small number of heat exchangers and requires a lower heat pump output relative to the total heating output and operates with a high degree of efficiency.

The solution to the problem is provided by the characterizing features of claim 1.

Advantageous embodiments are specified in the subclaims.

This arrangement has the advantage that the heat exchanger only needs to be relatively small and that it does not show any icing, since it is intended to work with a washing liquid which has such a high salt content that it does not freeze even at the operating temperatures ^below the freezing point of water which usually occur.

In order to achieve the best possible efficiency in heat pump operation under the given circumstances, i.e. heat demand and outside air temperature ratios, the temperature difference between the evaporator and the condenser is preferably kept as low as possible and the flow temperature of the heating circuit is set in accordance with the heat demand in a known manner. If the output of the heat pump is not sufficient to meet the required heat requirement for extraction from the ambient air, as is usual with so-called bivalent heating devices, the

Combustion device is switched on. This is suitably equipped with a direct heat exchanger, through which the heating circuit is heated, and upstream of this are the flow heat exchanger of the washing liquid and upstream of it the evaporator heat exchanger of the heat pump. The washing device is then advantageously only supplied with flue gas and no outside air, and the temperature of the washing liquid is preferably reduced to such an extent that the sulphurous acid in the flue gas also largely condenses.

It is also advantageously possible to extract part of the flue gas heat with a second scrubbing liquid circuit, which is arranged on the flue gas inflow side of the scrubbing device, through the return heat exchanger. The other scrubbing liquid circuit is then operated on the flue gas outflow side, which is routed via the evaporator heat exchanger of the heat pump system and is operated at a lower temperature. In this way, even more favorable entropy utilization is achieved.

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An advantageous embodiment of the device is shown in Fig. 1 |

I shown. g

It shows a heating device in side view, partially '';

cut and schematized, as well as the circuits, measuring

and control elements and the control device. Ej

A tower-shaped flue gas washing device (1) is ^ on the top with a nozzle assembly (2) for spraying the |

Washing liquid in the form of water screens (WS) or {,

/ spray rain. In the lower part there is a

Collecting basin (21) for the washing liquid, the outflow
(22) via a brine pump (23) through a supply line (23B) to the
Nozzle (2). The flue gases (RG) of a
Combustion device (3) are connected by a nozzle (13)
the washing device (1) above the collecting basin (21)
and, after passing through the trickle section of the
Washing liquid has passed through in countercurrent, at the top of the
Exhaust nozzle (AG) of the washing tower housing (11) cleaned and
cooled, from where they can be fed into a chimney.

The combustion device (3) is equipped in a known manner with
a controllable burner (31) to which fuel
(BS) and supply air (ZL). The flame and flue gases
(RG) pass through a heating register (32), the discharge and
supply line (32A, 32B) are connected to a controllable cross-way mixing valve (33) which on the other hand is connected to a
Heating circuit of radiators (35) which is heated by a heating circuit pump
(34) is connected to the heating circuit flow and return line (34A, 348). This heating circuit is
downstream of the radiators (35), which are also connected by a pipe network
a floor heating system, with the return
(35A) through a return heat exchanger (16) where it
from the heated by the flue gases, e.g. to 80 degrees C/
Washing brine is preheated and this, e.g. to 30 degrees C,

cools down so that it can be fed to the nozzles (2) again.

The cross-way mixer (33) can be connected in a known manner by hand or via a pre-run temperature sensor (33C) to a control drive (33D) for regulating a specific temperature on the pre-run line (34B) of the heating circuit (shown in dashed lines).

The burner (31) is controlled by a temperature sensor (32C) on the flue gas heat exchanger (32) between specified limit temperatures during operation.

In a further expansion stage, the device is supplemented by a heat pump (4), whose condenser (41) as the first heat exchanger supplies heat to the return flow (35A) of the heating circuit and whose evaporator (43) as the second heat exchanger extracts heat from the washing liquid before it is returned to the nozzles (2). Between the condenser (41) and the supply line of the evaporator (43) there is advantageously a controllable throttle (42), which is regulated to maintain a certain temperature with the signal from the temperature sensor (42O on the coolant outlet line (43A) of the evaporator (43) in order to achieve a favorable efficiency. The control connection of the temperature sensor to the actuator (42D) of the throttle (42) is shown in dashed lines.

Alternatively, the temperature of the washing liquid in the outlet (23A) behind the evaporator (43) can be measured and used for control. In order for the heat pump to have a high level of efficiency, the condenser (41) is arranged in the return (35A) of the heating circuit, i.e. where the lowest temperature prevails, and then the return heat exchanger (16) in the washing liquid, which is operated at a higher temperature, is arranged in terms of flow.

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which is connected to the heating circuit mixer (33).

This arrangement with the heat pump has the advantage that the flue gas energy is used even further and that the lower temperature of the washing liquid causes the pollutants, especially sulphurous acid and hydrocarbons, to be precipitated even further. It is within the scope of professional skill to add suitable agents in suspension or dissolved in the washing liquid which cause the pollutants to be chemically bound or precipitated and thus provide an even more extensive purification of the exhaust air.

In a further advantageous embodiment of the device, it is used as a so-called bivalent heating device, whereby when the heating demand is low, e.g. in the so-called transition period, the heat pump extracts heat from the outside air (AL) and the combustion device (3) is switched off. For this purpose, a fan (50) is arranged on the washing tower (1), which supplies the outside air (AL) to the washing tower (1) via an air supply pipe (51) at the bottom via the nozzle (13). A pendulum flap (52) alternately closes off the flue gas connection or the outside air connection. Furthermore, in parallel to the fan control with an actuator \' (45D), a bypass valve (45) is switched parallel to the return heat exchanger (16) and this is switched off via a non-return valve. The washing liquid circuit extracts heat from the supplied outside air in countercurrent, which is extracted from the washing liquid by the heat pump. In this way, the heat exchanger (43) can be kept small compared to a conventional air heat exchanger, and the fan (50) can be operated at a low power due to the low pressure drop in the scrubbing tower (1). This results in very little air flow noise.

The entire device is conveniently controlled via

a control device (ST) which is connected on the input side to a timer (CL), an input device for specifying comparison temperature values and to temperature sensors for the outside air temperature (ALC), the exhaust gas temperature (AGC), as well as the temperature sensors (33C, 42C, 32C) already mentioned. On the output side, it controls the burner (31) and the actuating devices (33D, 42D, 45D) of the mixer (33), the throttle (42) or the bypass valve (45) as well as the fan (50), the heat pump (4), the heating circuit pump (34) and the brine pump (23). The control is carried out in such a way that, as long as the exhaust gas temperature (AGC) does not fall below a specified lower value in heat pump fan operation and the flow temperature (33C) does not fall below a certain value, the fan, the heat pump and the brine pump are operated and the bypass valve is opened until a specified upper flow temperature is reached. The heat pump is then switched off and the

Fan and brine pump for a specified time or

until the exhaust gas temperature (AGC) is approximately equal to the outside air temperature (ALC), i.e.

< specified difference to it, whereupon this

' can be switched off.

j /·\ In this way, the heat pump can run with high efficiency when it is restarted and the flow temperature has reached its lower specified value again.

j · If heat pump operation for a given time is not sufficient to raise the flow temperature above a minimum value,

> the control device switches the fan off and the

S burner and closes the bypass valve (45). Depending

\ Depending on the flow temperature, the mixer (33) is then set to

' Circuit of the heating register (32) partially reversed.

\ The heat pump and brine pump are always installed parallel to the burner

operated and after its shutdown, which depends on

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from the time a predefined heating register temperature is reached (32C), they continue to operate until the exhaust gas temperature has reached a certain lower limit. The fan is switched on again if the outside air temperature (ALC) is above the exhaust gas temperature, and the heat pump operation control starts again.

A reliable method to short circuit the

The method of preventing heat transport between the heat exchangers (41, 16, 43) via Γ , the heating circuit or the brine circuit is to close the bypass valve (45) when the temperature at the supply line (16B) is higher than that of the brine in the collector (21). Sensors (16C, 21O) are arranged there for this purpose and are connected to the control device.

The economics of operating the device are determined by the electricity and fuel costs and the design of the individual heat exchangers, as well as the amount of brine, which can be advantageously increased by adding a tank. ^These conditions can be taken into account by selecting the specified temperature limits at which the various states are controlled, and by determining the specified times. To obtain suitable data, the temperature curves at the various temperature detectors are continuously output on an output device (AG) of the control device (ST). To make temperature designations easier to understand, the reference symbol of the detector has been added.

The specialist can supplement the device with additional parts, e.g. hot water preparation and storage, or the combustion device can be replaced by another heating device or dispensed with entirely, whereby the device is arranged as a new type of heat pump device upstream of the outside air for the purpose of heat extraction.

Claims (7)

Protection claims 1. Heating device consisting of a combustion device (3) which acts on a heating register (32) which is connected, preferably in a controllable manner, to a heating circuit (34J, 35) and the flue gas (RG) or alternatively a controlled outside air flow (AL) of which passes in a washing device (1) in countercurrent through a washing liquid in the form of water jets or a water screen (WS), which; in the lower area of the washing device (1) in a collector (21) and pumped back into the washing device (1) by a pump (23), the washing liquid being guided through a heat exchanger (43) which on the other hand contains an evaporator of a heat pump circuit of a heat pump (4), a throttle (42) and a condenser (41) thermally connected to the heating circuit being arranged in the heat pump circuit and a return line (35A) of the heating circuit (35) being guided through a heat exchanger (41) through which the heat pump circuit is guided on the other hand, characterized in that the return line (35A) of the heating circuit (35) is guided through the condenser (41). 2. Device according to claim 1, characterized in that in the return line (35) a second return line heat exchanger (16) is connected downstream of the condenser heat exchanger (41), through which the washing liquid flows on the other side. 3. Device according to claim 2, characterized in that a controllable bypass valve (45) is arranged parallel to the second return heat exchanger (16) and a return stop (44) is arranged in series with this heat exchanger (16). 4. Device according to claim 3, characterized in that the washing device (1) has a tower-shaped housing (11) in which a nozzle assembly (2) is arranged at the top and in the lower area of which an outlet nozzle (11) is arranged pointing downwards for the flue gas (RG) or the outside air (AL). & ""' U Il ■ · · · · &igr;&bull; · · · tii &igr;, 5. Device according to claim 4, characterized in that between the flue gas supply and the outside air supply a A pendulum flap (52) is arranged which alternately opens and closes the feeds. 6. Device according to one of the preceding claims, characterized in that two separate washing liquid circuits are arranged in the washing device (1), of which one is located on the flue gas inflow side and is connected to the second return heat exchanger (16) and the other (~\ is located on the flue gas downstream side and is connected to the evaporator heat exchanger (41). 7. Device according to one of the preceding claims, characterized in that on the heating register (32), a Pre-flow line (34B) of the heating circuit (35), a Evaporator outlet line (43A), in the outside air (AL), in the exhaust gas (AG), the washing device (1) in the collector (21) and on the supply line (16B) of the return heat exchanger (16), temperature detectors (32C, 33C, 42C, ALC, AGC, 21C, 16O) are arranged, which are connected on the input side to a control device (ST), which can also be preset by a timer (CL) clock pulses and by an input device * ' CEG) limit temperatures and comparison times and which are connected on the output side to the control inputs or actuators of the burner (31), the heat pump (4), the pumps (34, 23) in the heating or washing liquid circuit, the bypass valve (45), the throttle (42) and a mixer (33)/ which is arranged between the heating register (32) and the heating circuit (35). lsi, is connected.