EP3239616A1 - Infrared heater for heating a building and method for heating a building with such an infrared heater - Google Patents

Abstract

An infrared heater (1) for heating buildings, comprising a radiant tube (2) and a burner (4) fluidly connected thereto at a first end, via which the radiant tube (2) a gas (6) heated by the burner (4) ) is supplied, by means of which the radiation tube (2) for emitting infrared radiation on its surface is heated, characterized in that the radiation tube (2) has an electrical resistance heater (8), with which this at least partially with electric current a current source (14, 14a) is heatable. The invention further relates to a method for heating a building using such an infrared heater (1) which is characterized in that the electrical resistance heating introduced by the electrical resistance heater (8) in the radiation tube (2) from the first burner end increases in the flow direction of the hot gas.

Description

The invention relates to an infrared heating device for heating a building and to a method for heating a building with such an infrared heating device according to the preamble of claims 1 and 11.

Heating systems for heating large buildings, in particular halls, which comprise a plurality of individual infrared radiators, in particular dark radiation, have long been sold by the applicant and are also, for example, from DE 10 2007 047 661 A1 known. The dark radiators comprise a housing which is suspended horizontally above a region of the building which is to be heated and in which a radiation tube is accommodated which is acted upon by a gas burner with heated exhaust gas. The other end of the radiant tube is acted upon by a suction fan with negative pressure and is connected to an exhaust pipe. Due to the thus generated temperature of the usually black outside of the radiant tube in the range of 300 ° C to 750 ° C radiates this infrared radiation in the manner of a black body, which leads to a direct heating of the residence area of people below the radiant tube. This is compared to conventional building heaters, in which hot air heaters are used, the advantage that in a building only the surfaces of people, animals and objects are heated by the infrared radiation, but not the volume of air within the building. Since in this case no air is heated in the floor area of the hall, which subsequently rises and is no longer available in the occupied area of the persons as warm air, the infrared heaters described operate comparatively economically and are therefore preferably used for heating halls.

Furthermore, it is known to generate electrical power through photovoltaic systems, each having a plurality of photovoltaic modules that generate electrical energy from the incident sunlight, which is fed back known about inverter in the public grid. Due to the share of regenerative energy production facilities, which has grown strongly in recent years, which is connected to the electric Power supply are connected, the production of electrical energy is subject to strong fluctuations, which can often lead to local overloads of the power grid lack of adequate energy storage, so that on the part of the operators of the power grids for the purchase of electrical energy at peak times even allowances for the power taken be paid to favor the decrease of electrical energy at peak times.

In the aforementioned infrared heaters, the problem arises that they can be heated exclusively with gas, without the possibility of this, with an excess of electrical energy in the public power grid, such as occurs on cold sunny and windy winter days, to use efficiently for heating buildings.

Another problem with the aforementioned infrared heating systems is that the surface temperature of the radiant tubes progressively decreases due to the cooling of the hot gases from the burner-side end to the downstream end of the tube. By the T ⁴ - dependence of the intensity of the radiated infrared radiation on the temperature (Stefan Boltzmann law) decreases the intensity of the infrared radiation from the burner end to the downstream end of the radiation tube out disproportionately, resulting in that the intensity of the radiated infrared radiation on the Length of the radiation tube is not constant. Since the maximum permissible surface temperature of the radiation tube is due to the material at about 650 ° C, the maximum possible intensity of infrared radiation is obtained only in the first portion of the radiant tube, whereas converted to the downstream end of the tube out only a small portion of the heat energy contained in the hot gas in infrared radiation becomes. Since the efficiency of the overall system relative to the primary energy used when heating large buildings such as halls is higher, the greater the proportion of emitted from the radiant tube infrared radiation, the overall efficiency of the dark radiator due to the cooling-related decrease in the temperature of the radiant tube thereby adversely reduced ,

Accordingly, it is an object of the present invention to provide an infrared heater having a hot gas applied radiant tube which enables more efficient heating of a building with both a fossil fuel and electric power.

This object is achieved by the features of claim 1.

Furthermore, it is an object of the present invention to provide a method of heating a building with an infrared heater, which can reduce the need for fossil fuels necessary for the operation of the heater.

This object is achieved by the features of claim 11.

Further features of the invention are described in the subclaims.

According to the invention, an infrared heating device for heating buildings comprises a radiant tube and a burner connected thereto in fluid communication at a first end, in particular a gas or oil burner, which heats the radiant tube in a known manner with heated exhaust gas which projects the radiant tube on its surface a temperature of eg Heated to 600 ° C, so that this infrared radiation in the manner of a black body or dark radiator radiates into the building to be heated.

The infrared heating device according to the invention is characterized in that the radiation tube has or contains an electrical resistance heating with which it can be heated at least in sections additionally or alternatively to the heating by the burner with electric current of a power source.

The invention provides the advantage that with an excess of electrical power in the public network, as can be observed for example on cold windy and sunny winter days, the excess energy can be used in an efficient way for heating buildings, in which already Infrared heater is installed with dark radiators. In the simplest case, in order to operate these, it is only necessary to electrically insulate the radiant tube from its suspension in the area of the hall ceiling and the burner and to apply electrodes, for example to the outside of the radiant tube, to a power source, preferably the public 50 Hz AC mains. Network, to connect.

Another advantage resulting from the solution according to the invention can be seen in the fact that the burner is operated at a lower power and the additional proportion of energy required to achieve the optimum surface temperature of the radiant tube can be obtained from the electrical power network via the resistance heating. As a result, the overall heating costs can be considerably reduced, in particular if there is an excess of electrical current in the power grid.

According to another underlying idea of the invention, the radiation tube comprises at least a first electrically conductive portion which may also comprise the entire radiation tube, if this consists as usual of sheet steel with a wall thickness of for example 1.5 mm. In this embodiment, the resistance heating comprises at least first and second electrical contact elements arranged at a distance from one another at the partial section, which can be connected to the electric current source via an electrical switching device in order to connect the electrically conductive partial section, i. to energize the lying between the two electrical contact elements area of the radiation tube. This embodiment of the invention has the advantage that it can be retrofitted to existing infrared heaters with little effort, since the radiation tubes for this purpose only electrically insulated and two electrodes at a distance from each other must be attached to the radiation tube, for example by a clamp or the like.

In the preferred embodiment of the invention, in addition to the first subsection, at least one or preferably also a plurality of further electrically conductive subsections are defined on the radiation tube, which can be provided by attaching a corresponding number of electrical contact elements / electrodes to the outside of the radiation tube. The plurality of electrically conductive sections are preferably each individually or in groups on the electrical switching device with the power source, that is preferably the AC electrical network, connectable, for example, two or more of the sections as needed to turn on or off and accordingly from the Radiation tube emitted into the building radiant power of the infrared radiation to a desired level.

In order to activate the electrically conductive subsections in the last described embodiment of the invention, each subsection is the plurality of electrically conductive subsections connectable to the power source via a respective electrical contact element and a switch associated therewith. Although the switches may also be mechanical contact switches such as manually operated mechanical switches or relays, in the preferred embodiment of the invention preferably electronic switches are used, such as high power semiconductor switches, which are preferably controllable by a corresponding electronic control device of the electrical circuit direction via a bus system.

In this case, it is of particular advantage if the electrical switching device opens and closes the switches with a preferably variable clock frequency and / or a variable duration in order to change the electrical heating power generated in the respective subsection on average. This opens up the possibility to set the heating power in the respective electrically conductive sections of the radiation tube with a comparatively high accuracy to a predetermined value, or to regulate such, which with the known, exclusively heated by a burner radiation tubes due to the modulation of the Burner required control devices is possible only with great effort. In addition, due to the cooling of the hot gas due to the cooling of the surface of the radiant tube from the burner end to the downstream end in the known, purely gas powered dark radiators with a single radiant tube was previously not possible, the decrease in the surface temperature over the length of the Compensate radiation tube at all. This is now made possible for the first time by the solution according to the invention.

In other words, it is possible with the inventive solution described last, the surface temperature of the radiant tube by a corresponding adjustment of the current, and the on and off frequency of the respective electrical switch, via which the current flow in the subsection is switched on or off, to regulate according to a predetermined temperature profile. This control is particularly advantageous in a mixed operation of the heater, since this not only reduces the fuel consumption of the burner, but also the infrared radiation efficiency can be increased overall, in simplistic terms also the otherwise colder downstream areas of the radiant tube through the targeted supplied electrical Heating energy to be raised to the desired surface temperature.

In a particularly simple and cost-effective manner, the embodiment described above can be realized in practice in that the radiation tube is made entirely of an electrically conductive material, in particular stainless steel, and the contact elements at preferably equal distances from each other over the length of the radiation tube on or on away the radiation tube are arranged. Although the current source can also be an electric DC power source whose positive and negative poles are alternately electrically connected successively over the length of the radiation tube with the contact elements, this is in the preferred embodiment of the invention, an AC power source whose neutral and whose at least one phase alternately electrically conductive over the length of the radiation tube away with the contact elements are connectable. By this circuit arrangement there is the advantage that with a minimum number of electrical switches and contacts a plurality of electrically conductive sections of the radiation tube can be heated individually or in groups.

Although the power source in the above-described embodiments of the invention is preferably a power source having a fixed AC frequency, according to another aspect of the invention, it is also possible to use an AC electric power source having a variable frequency. This makes it possible to set the frequency of the AC voltage, for example, to a few 100 Hz or even kilohertz, which due to the so-called skin effect, the electric current flow is shifted in the region of the outside of the radiant tube, which advantageously leads to that in a mixed operation in particular downstream portion of the radiant tube a smaller proportion of the supplied electric heating power passes to the cooler exhaust gas in this area and is discharged therefrom. Also in this embodiment of the invention, it is possible that the supplied heating power is not the height of the alternating current but over the cycle times, with which it is supplied to the corresponding electrical sections, is changed.

In order to make the adjustment of the surface temperatures of the radiant tube in the different electrically conductive sections of the radiant tube in control technology particularly easy, it may further be provided that the electrical switching device, the current flow and / or the frequency of the current flow, ie the on and off frequency the switch, in one or more of the electrically conductive sections in such a way that the difference in the surface temperatures between the electrically conductive sections in the region of the first end and the electrically conductive sections in the region of the second end of the radiation tube is reduced. For this purpose, the temperature in the respective subsections / heating zone of the resistance heater may be detected via sensors, such as infrared sensors.

In order to be able to use the principle of a combination of a known hot-gas-charged radiation tube with an electrical (ohmic) resistance heating not only in new plants but also in already installed old plants in a simple manner in retrospect, the principle underlying the inventive infrared heater, it may continue to be provided that the radiation tube is received in a holder made of an electrically insulating material which has a sufficient temperature resistance. This material is preferably a ceramic material.

In this context, it is also advantageous if the radiation tube is electrically isolated from the burner by an electrically nonconductive separating element, such as a ceramic disc or a ceramic neck, as well as by a blower sucking the hot gas from the second end of the radiant tube.

According to a further idea underlying the invention, the electric current source in the method according to the invention for heating a building with a previously described infrared heating device is a public power grid or a photovoltaic system. According to the method, in the event of an excess of electrical energy in the public power grid or an excess of electrical energy produced by the photovoltaic system, the electrical resistance heating is activated and the radiant tube is electrically heated exclusively or in addition to the thermal energy generated by the burner. In this case, it is particularly advantageous if the electrical heating power introduced into the radiation tube by the electrical resistance heating is increasingly increased in the flow direction of the hot gas from the first burner end, so that the surface temperature over the length of the radiation tube, which for example is 5 m or even more can be, is constant or corresponds to a desired temperature profile.

In order to increase the proportion of radiated from the radiant tube into the building infrared radiation as much as possible and accordingly to increase the overall efficiency of the infrared heater accordingly, it may be provided according to another of the invention underlying thought, the heat output generated by the burner in particular to reduce by reducing the amount of fuel supplied and a corresponding reduction in the air supply to the burner to the extent that the heating power provided by the electrical resistance heating is increased.

The invention will be described below with reference to the drawing with reference to a preferred embodiment.

Fig. 1

eine schematische Darstellung der erfindungsgemäßen Infrarot-Heizeinrichtung, bei der das Strahlungsrohres in insgesamt neun elektrisch leitende Teilabschnitte, bzw. Heizzonen unterteilt ist, die über entsprechende Schalter einzeln oder in Gruppen elektrisch beheizbar sind.

In the drawing shows:

Fig. 1

a schematic representation of the infrared heater according to the invention, in which the radiation tube is divided into a total of nine electrically conductive sections, or heating zones, which are electrically heated via respective switches individually or in groups.

As in Fig. 1 1, an infrared heater 1 according to the invention for heating a building, which is not shown in more detail, comprises a radiation tube 2 which is connected at its first end in known manner to a burner, in particular a gas burner or an oil burner 4, which surrounds the interior of the radiation tube 2 is heated with heated exhaust gas to heat it to a surface temperature of, for example, 600 ° C or more. As is usual with such infrared heaters, the exhaust gas 6 of the burner 4, which increasingly cools due to the heat exchange with the inner wall of the radiant tube 2 from the burner end to the downstream end, is exhausted by a fan 20, which is representative of a suction device which In particular, the fan of a collective exhaust system may be, to which a plurality of radiant tubes 2 are connected.

As the representation of Fig. 1 can be removed, the radiation tube 2 has an electrical resistance heater 8, with which this can be heated by an electric current source 14. The current source 14 forms at the in Fig. 1 In the illustrated embodiment of the invention, the public 50 Hz AC grid, whose phase P and Neutral conductor N are also connected via a symbolically shown inverter 14b with a photovoltaic system, which is exemplified by the photovoltaic module 14a.

As the representation of Fig. 1 can be removed, the radiation tube 2 is received in brackets 16 made of an electrically insulating material and electrically isolated via electrically non-conductive separating portions 18 of the burner 4 and also from the fan 20.

The radiant tube 2 in the embodiment shown consists of metal in a known manner, e.g. made of stainless steel, and is divided from its burner-side end to its downstream end into a plurality of electrically conductive sections A1 to A9, each forming a heating zone and are defined by the associated contacts K1 to K10. As shown, the contacts K1 to K10 are alternately connected to the neutral N and the phase P of the AC electrical network 14, wherein in the illustrated embodiment, only the phase connected electrical contact points K2, K4, K6, K8 and K10 via electrically actuated switch S1 until S5 are connected to the phase P. By contrast, the remaining contacts K1, K3, K5, K7 and K9 are connected directly to the neutral conductor N of the alternating current network 14, which advantageously reduces the circuit design and the required number of electrical switches S1 to S5. Nevertheless, it is also possible to provide the contacts K1, K3, K5, K7 and K9 connected to the neutral conductor N with corresponding electrical switches which open in the same way as the other switches via an electrical switching device 12 and a bus system indicated by dashed lines and / or can be closed to electrically heat the individual sections A1 to A9 according to a desired temperature.

In order to increase the heating power in the different heating zones, which are defined by the sections A1 to A9 successively from zone to zone successively from the burner end to the blower end, switching on and off of the switches S1 to S5 is preferably clocked with different clock rates and / or switch-on, as is known, for example, from the control of electric DC drives according to the so-called electrical pulse width modulation method ago. This results in the advantage that the electrical power transmitted to the radiant tube 2 in the respective heating zones, which leads to a heating due to the ohmic resistance of the material of the radiant tube, without a complex individual control of the current in each heating zone, or the relevant Modify subsections A1 to A 9. The above applies in the same way for the case that the power source is a DC electrical source such as a photovoltaic module 14a, in a corresponding manner, bypassing the inverter 14b directly through the respective contacts K1 to K9 and unspecified electrical protection devices with the radiation tube 2 can be connected.

According to an embodiment of the invention, not shown in detail, between the blower 20 and the downstream end of the radiant tube 2, a heat exchanger may be arranged which extracts the thermal residual energy of the hot exhaust gas 6 from this and this example, a buffer memory, from which the recovered heat energy a conventional convection heating, or a hot water dispenser can be supplied, which is preferably located in a second, thermally insulated from the region of the radiant tube 2 building part. As a result, the advantage is obtained that the part of the introduced in particular in the downstream part of the radiant tube 2 electrical heating energy, which passes to the cooler exhaust gas 6 and this heated in an undesirable manner, can be recovered to a large extent.

LIST OF REFERENCE NUMBERS

1

Infrared heating device according to the invention

2

radiation tube

4

burner

6

heated gas / exhaust

8th

electrical resistance heating

12

electrical switching device

14

power source

14a

Photovoltaic system

14b

inverter

16

electrically insulating holder for radiation tube

18

non-conductive separator

20

fan

A1 - A9

electrically conductive sections of the radiant tube / heating zones

S1 - S5

switch

K1 - K10

electrically conductive contact elements

P

electric phase of the power grid

N

electrical neutral

Claims (13)

Infrared heating device (1) for heating buildings, having a radiant tube (2) and a burner (4) fluidly connected thereto at a first end, via which the radiant tube (2) a gas (6) heated by the burner (4) can be fed, by means of which the radiation tube (2) can be heated to emit infrared radiation on its surface,
characterized,
that the radiant tube (2) comprises an electrical resistance heater (8), with which this at least in sections with electric current of a current source (14, 14a) is heated. Device according to claim 1,
characterized,
that the radiant tube (2) at least a first section (A1) made of an electrically conductive material, and that the heating resistor (8) at least a first and second spaced apart on the section (A1) comprises arranged electrical contact element (K1, K2), which is connectable via an electrical switching device (12, S1 to S5) with the electrical power source (14, 14a). Device according to claim 2,
characterized,
in that the radiation tube has a multiplicity of electrically conductive sections (A1 to A9) which can be connected individually or in groups to the current source (14, 14a) via the electrical switching device (12, S1 to S5). Device according to claim 3,
characterized in that
Each subsection of the multiplicity of electrically conductive subsections (A1 to A9) can be connected to the current source (14, 14a) via a respective electrical contact element (K1 to K5) and a switch (S1 to S5) assigned to it. Device according to claim 4,
characterized in that
the electrical switching device (12) opens and closes the switches (S1 to S5) with a preferably variable clock frequency and / or a variable duration in order to change the electrical heating power generated in the respective subsection (A1 to A9). Device according to claim 4 or 5,
characterized in that
the radiation tube (2) as a whole consists of an electrically conductive material, in particular stainless steel, that the contact elements (K1 to K10) are arranged at preferably equal distances from one another over the length of the radiation tube (2) on the radiation tube, and that the current source (14 , 14a) is a DC electrical source whose positive poles and negative poles are alternately connected electrically in succession over the length of the radiation tube (2) to the contact elements (K1 to K10), or that the current source (14, 14a) is an AC source whose phase (P) and neutral (N) alternately over the length of the radiation tube (2) of time electrically conductively connected to the contact elements (K1 to K10) are connectable. Device according to one of the preceding claims,
characterized in that
the current source (14) is an electrical alternating current source with a preferably variable frequency. Device according to one of claims 3 to 7,
characterized in that
the electrical switching device (12) changes the current flow and / or the frequency of the current flow in one or more of the electrically conductive sections (A1 to A9) in such a way that the difference of the surface temperatures between the electrically conductive sections (A1 to A4) in the range of the first end and the electrically conductive sections (A5 to A9) in the region of the second end of the radiation tube (2) is reduced and / or a predetermined Temperature profile corresponds. Device according to one of the preceding claims,
characterized in that
the radiation tube (2) is accommodated in a holder (16) made of an electrically insulating material, in particular in a holder (16) made of a ceramic material. Device according to one of the preceding claims,
characterized in that
the radiation tube (2) is electrically separated from the burner (4) and / or a fan (20) sucking the hot gas (6) from the second end of the radiation tube by an electrically nonconductive separating element (18), in particular a ceramic disk or a ceramic socket , Method for heating a building with an infrared heating device (1) according to one of Claims 1 to 10,
characterized,
that the electric current source (14) is a public power grid or a photovoltaic system, and that in the event of an excess of electrical energy in the public power grid or an excess of electrical energy produced by the photovoltaic system, the electrical resistance heater (8) is activated and the radiation tube (2) is exclusively electrically heated in addition to or in addition to the thermal energy generated by the burner (4). Method according to claim 11,
characterized,
that of the electrical resistance heater (8) increases introduced into the radiant tube (2) electrical heating power of the first burner end as viewed in the flow direction of the hot gas. Method according to claim 12,
characterized,
the heating power generated by the burner (4) is reduced to the extent that the heating power provided by the electrical resistance heater (8) is increased.

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