DK148726B - TEMPERATURE SENSOR CONTROLLED CONTROLLER FOR A GAS COVERED WATER OR AIR HEATER - Google Patents

Description

148726

The invention relates to a temperature sensor controlled control apparatus of the kind specified in the preamble of claim 1, e.g. is known from GB-PS 1,235,891. In order to optimally utilize the fuel supplied to a burner, not only is it required that the fuel supply is adjusted according to the heat demand, but also that the combustion air supply to obtain an optimal combustion is adjusted according to fuel quantity.

To this end, the construction known from the aforementioned British patent specification has a spring-loaded control diaphragm element which is connected to a temperature sensor controlled gas control valve for the burner leading outlet line and controls an air damper in the combustion air supply duct. The greater the amount of gas fed to the burner, the more the damper is opened, thus increasing the amount of combustion air supplied over a fan. In another embodiment of this known control apparatus, the said control membrane element controls over the fan speed of a brake, and in this way regulates the combustion air supply.

DE-OS 1.529.184 also discloses an apparatus for controlling the supply of gas and air to an infrared burner, where an air damper is built into the combustion air duct. This is influenced by a pressure regulator which keeps the pressure in the duct constant and is also operated by a servo motor controlled by a temperature sensor. The air flows over a nozzle opening into a mixing chamber, which at the same time gets a combustion gas supplied over a nozzle. It is sought that the air pressure seen in the flow direction after the nozzle opening and the gas pressure seen in the flow direction after the nozzle be equal. For this purpose, the air duct over a plug line is connected to the control chamber by a pressure regulator which acts on a valve inserted in the gas line.

3

It is known that for optimum combustion of 1 m of ground gas, approx. 10 m of combustion air. In conventional water heaters 30, an injector nozzle connected to the gas supply line is used for the supply of gas and combustion air, which opens into the burner, and whose gas stream simultaneously sucks an appropriate air flow and leads it to the burner. Under this, the gas / air ratio also remains approximately the same, with approx. 6: 1. Thus, at this primary air suction, only 35 60% of the required combustion air. This means that an additional secondary air supply must supply the remaining 40% of combustion air. To date, additional air intake holes have been fitted in the burner housing, the size of which is adapted to the maximum fuel flow rate.

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However, this means that, with low gas supply, a significant excess of air is present and therefore the efficiency of the combustion air is greatly reduced.

DE-OS 2,251,994 discloses an apparatus for mixing gas 5 and air for producing a fuel gas, and where the gas, under a driving pressure, enters a jet pump equipped with an air suction plug and a venturi for mixing the air with the gas.

. The venturi opens into a mixing chamber. The apparatus further has a second jet pump whose input is connected to a compressed air generator and also conducts an additional flow of air into the mixing chamber. The Blan chamber is fitted with a fuel gas outlet socket, which opens into a gas supply network. At both jet pumps, the suction air flow can be controlled manually by means of an air damper located in the suction nozzle. Since the common mixing chamber supplies a city gas network 15 with a fuel gas / air mixture, which is simply required to have a uniform composition, without requiring an adaptation to different amounts, a common regulation of the two jet pumps is neither intended nor intended. required.

Finally, from the specification of U.S. Patent No. 2,193,240, a combustion gas and air mixer is known by means of which a gas mixture having a constant heat value must be provided and maintained. For this is one. air valve and throttle body throttle members are rigidly connected to each other and together controlled by the output of one differential pressure regulator which measures the differential pressure at the gas valve.

Furthermore, the differential pressure at the gas valve and the differential pressure at the air valve is applied to a differential pressure comparing means, the turnover ratio of which can be changed by the output of a heat exchanger connected to the mixing conduit, and the output of which controls a second air valve arranged in front of said air valve. determined relationship between the two differential pressures. Neither is this apparatus intended for a consumption dependent, e.g. temperature dependent, regulating the amount of gas mixture.

The invention is also for water or air heaters with gas supply over an injector nozzle which simultaneously sucks combustion air, to achieve simultaneous regulation of the gas supply and the combustion air supply in such a way that even with varying heat demand and thus varying fuel supply during all. conditions, the burner is supplied with the optimal fuel / air mixture. This assignment . is solved according to the invention by means of the characteristics specified in claim 1, part 148726 3. With the use of a servo pressure regulator, the advantage / bite of the gas control valve and the air flow control means is only to process relatively small gas and suction air flows, respectively, while the primary air and the greater part of the secondary air are supplied to the burner by means of the suction effect of the injector nozzles (venturi nozzles). Furthermore, it is a particular advantage that due to the closed house, there are hardly any features of a disconnected burner, so that the heat in the burner does not escape through the chimney. This, together with the optimum 10 combustion, results in further energy savings. The use of a servo pressure regulator has the advantage that the main gas valve in the event of a failing gas supply pressure is automatically closed by means of its closing spring and thus keeps the gas path blocked.

Advantageous embodiments of the invention are set forth in the claims. The invention is explained in the following with reference to some embodiments illustrated in the drawing. In the drawing:

FIG. 1 and 2 are in combination an embodiment in which the servo pressure regulator is mounted on a gas control apparatus and the auxiliary secondary air valve over a line is connected to the servo pressure regulator; and fig. 3 and 2 in conjunction with one embodiment in which the servo pressure regulator is mounted on the air valve and the gas regulator is connected over a line to the pressure regulator. FIG. 1 shows the gas valve and the servo pressure regulator as well as the air control valve with a fan arranged in front of it, while FIG. 2 as a consumer shows a gas-fired boiler, e.g. for a central heating system.

30 Over a line 20, a servo pressure controlled air control valve for the control membrane chamber 32 is connected to the chamber of the servo pressure regulator. The closure member 33 is carried over a pin 34 by the membrane 35 and is biased in the closing direction by a spring 36. The inlet 37 of the air control valve is connected to a source of compressed air in the form of a blower 38, while a flow switch 41 is provided in the outlet 30 of the sensor 40. Its working contact, which is closed by means of the air flow, lies in the magnetic circuit of the switch solenoid valve 4.

FIG. 2 shows, as a consumer, a heat exchanger 52 surrounded by a closed housing 51, whose heated water above the outlet 53 is fed to one or more heaters. A main burner 54 heats the heat exchanger 52 and an ignition 55 is connected to the gas control device's ignition connection 65, and a thermocouple 56 which monitors the flame extinguisher is connected to the magnetic insert 14. The combustion gases leave the housing 51 through a vent 57. inlet 58 there is an injector nozzle 59 over which the gases exiting from the gas control valve outlet 5 flow into the main burner. Due to the jet effect of the nozzle 59, the gas stream simultaneously sucks primary air supplied to the main burner 54 as combustion air. Furthermore, the housing 51 has an inlet 60 for secondary air and next to the inlet 60 there is an additional injector nozzle 61. This is fed with compressed air from the air control valve 32 and also, because of its radiant effect, sucks additional combustion air into and presses it into the interior of the air. the housing 51, where it is provided to the main burner 54 to obtain as complete combustion as possible. Apart from this, the housing 51 is closed.

In the embodiment described, at increasing gas volume 20 at the outlet of the gas control apparatus 5, the amount of compressed air that the air control valve 32 allows to pass through will also increase, and because of the jet effect of the two nozzles 59 and 61, the main burner 54 will be supplied as much as primary air and secondary air respectively. is required for a complete and optimal combustion of the amount of gas supplied. The amount of gas supplied via the gas control valve to the nozzle 59 is controlled by the servo pressure regulator 10, depending on the temperature monitored by the temperature sensor 11. If, in the absence of heat demand, the solenoid valve 7,8 is switched, thus blocking the connection between the chambers 9 and 19, it turns out that the connection of the air control valve 32 to the chamber 19 has the advantage that the closing of the main valve due to the separation of the chamber 19 from the chamber 9 by closing the valve 8 is not delayed due to the extra volume of the control membrane chamber 31. The latter, on the contrary, is separated from the volume of the chamber 3 so that the pressure prevailing therein can be rapidly reduced over the duct 6, the valve 8 and the duct 26 leading to the outlet side, so that the main gas valve 1 is closed.

Since the housing 51 except the secondary air inlet 60 and the flue gas outlet 57 is closed on all sides, there is virtually no feature of the housing 51 in the case of interrupted gas and secondary air supply, so that the heat therein cannot escape through the extractor 57. The inlet opening 60 is substantial. smaller than usual air boilers secondary air slots, the main part of the secondary air being suctioned as a result of the jet effect of the nozzle 61. If this jet effect is eliminated, only a negligible amount of air will flow through the inlet 60.

In FIG. 1 is a dotted line showing a modified embodiment in which the air control valve 32 lapses and instead a pneumatic-electric converter 42 is connected to the control air line 20. The inverter 42 is fed e.g. with the AC alternating voltage and 10 at its output delivers a direct current proportional to the pneumatic input signal of the fan motor 43 of the blower 38. Thus, at increased gas flow at the outlet of the gas control valve 5, the fan speed, thus increasing the amount of air transported by the blower 38, is increased. regulating the amount of gas and the amount of air. The conversion of the inverter 42 * pneumatic input signal to a signal which controls the engine rpm can be done in a known manner by means of a work angle control or a pulse length control.

According to a further embodiment of the invention, the embodiment of FIG. 2 to the boiler 51 shown in FIG. 3. Here, the servo pressure regulator 10 does not act on the gas control apparatus 67, but on the air control valve 72. Thus, the gas quantity is fed according to the amount of air supplied. For both those of FIG. 1 and 3, any leakage in the conduit 20 applies to the closing of the gas valve and the air valve, so that the apparatus itself has a built-in safety function. The FIG.

3 also has the advantage that the servo pressure regulator does not operate with gas, but with air, and thus, in the event of leaks, gas cannot be avoided. This makes it possible to produce the servo pressure regulator of less demanding materials, e.g. of plastic. The same applies in both cases to the air control valve. A further advantage of the embodiment shown in FIG. 4, the flow switch 40, 41 can be omitted. In this embodiment, the gas valve 67 can only be opened if the fan 38 35 is in operation and thus an air flow occurs.

In connection with the embodiment shown in FIG. 1, it is further noted that the gas valve closes immediately when the heating demand ceases, while the air control valve 32 is first moved to the fully open position, so that the pre-rinse of the combustion chamber is flushed. Only when the fan 38 is stopped, the air supply stops. To stop the fan 38, a switch is used which is terminated by activating the solenoid valve 7,8 and by de-magnetizing the solenoid valve 7,8 while simultaneously interrupting the connection between the fan motor and the mains.

An adjustable throttle member 73 arranged between the air control valve 32 and 72, respectively, and the additional injector nozzle 61, enables the setting of a desired gas / air ratio and thus of an adequate excess air for good combustion. Because of the use 10 of the two injector nozzles 59 and 61, the compressed air source 38 need only supply a relatively small amount of air. For example, the fan 38 without the 3 injector nozzles should carry approx. 10 m of air for combustion of 1 m of natural gas at 20% air excess. On the other hand, when using the injector nozzles 3, the blower 38 itself only delivers approx. 0.5 m. It is also an advantage that it is not only possible to equalize the gas supply at varying supply pressures, but that this also applies to the air supply.

Claims (3)

148726 Patent Claims. A regulator for a gas-fired water or air heater (51), which is controlled by a temperature sensor (11) and has a control valve (1-5) for the fuel gas supply and a control element accordingly (31-39; 42). ) for supply of combustion air, characterized by the following characteristics: a) a servo pressure regulator (10) compares the pressure at the output (5 or 39) of the gas control valve (1-5) or the air flow control element (31-39) with one of the temperature sensor (11) determines the desired value and controls with its output pressure both the control means (2-4) of the gas control valve (1-5) and the air flow control element (31-36; 42.43) control means (31,34,35,36; 43); b) the gas control valve ( 27) outlet (5) is connected to an injector nozzle (59) which is adjacent to the inlet (58) of the burner (54) and at the same time sucks primary air for the burner; C) the burner (54) and a heat exchanger surface (52) heated by the burner are surrounded by a housing (51) having a secondary air inlet (6) and a flue gas extractor (57); D) another injector nozzle (61) which is located off the secondary air inlet (60) and in operation sucks secondary air, is connected as a regulating means to an adjustable compressed air source (38,43,32), whose control input (44; 45) star in connection with the servo pressure regulator (10). Control device according to claim 1, characterized in that a pneumatic / electric converter (42) is inserted between the servo pressure regulator (10) and the fan motor (43). Control device according to claim 1, wherein the adjustable compressed air source consists of a fan (38) and an air control valve (32) disposed thereafter, characterized in that the servo pressure regulator (10) is mounted on the housing of the gas control valve (27) and that the air control valve (32) ) control membrane chamber (31) over a control