FR2611030A1 - Gas-fired air heater - Google Patents

Abstract

Production of hot air. The air heater comprises: . a modulating burner 12 associated with means for controlling its operation, . and a heat exchanger comprising: - a main exchanger 14 forcing the combustion gas to be conveyed in a direction counter to that of a stream of air to be heated, - and an auxiliary condensation exchanger 20 arranged between the outlet of the main exchanger and the stream of air to be heated. Application to apparatuses for heating rooms (premises).

Description

GAS AIR HEATER
The present invention relates to the technical field of the production of hot air, from the combustion of a gas, natural or artificial, delivered under pressure.

 The technical field, more specifically targeted, is that of the production of hot air reserved for the heating of industrial or domestic ocals.

 The production of hot air is ensured, up to now, by air heaters comprising a gas burner delivering, in a combustion chamber, a combustible mixture whose burnt gases are required to borrow flues arranged parallel to each other and vertically to connect the combustion chamber to a collector or flue gas evacuation box.

 The intervals, remaining between the flues, are traversed by an air stream pulsed by a motor-fan group to lick the external faces of the flues, take a part of the calories provided by the combustion of the combustible mixture and then distribute these calories. in the room where such an air heater is installed.

 The devices, designed for. assume the above function, are reputed to be bulky and to have only a low yield.

 The present invention aims to remedy these drawbacks by proposing a gas air heater designed to increase, notably, the combustion efficiency of the supply fuel, in order to be able to have, in a small volume, an increased heating capacity compared to to traditional devices.

 Another object of the invention is to propose a new gas air heater which can be produced in a compact manner and thus allow its installation as a placed or suspended device.

 Another object of the invention is to propose a gas air heater whose operation is automatically modulated according to the needs detected by means of controlling the ambient temperature.

To achieve the above objectives, the gas air heater, of the type comprising a burner, a combustion chamber, a heat exchanger through which the burnt gases emanating from the combustion chamber and a motor fan whose output pulses a vein d air to be heated through the heat exchanger, is characterized in that
- the burner is of the modulating type and is located
associated with means of sound control
operating under the control of a
regulator appreciating the difference between the
room temperature and a temperature of
instructions,
- and the heat exchanger includes
a main exchanger requiring gas from
combustion, between the combustion chamber
and an Exit smoke box, a
tracking along directions
vertical alternating progressing to
misinterpretation of that of circulation of the
air stream pulsed by the fan motor,
an auxiliary exchanger known as condensing
part of which is included in the box
smoke and of which another part rises
between the main exchanger and the outlet of the
motor fan.

 Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

 Fig. 1 is a schematic sectional elevation of the gas air heater according to the invention.

Fig. 2 is a cross section taken along the line
II-II of fig. 1.

 FIG. 3 is an illustrative diagram of the supply circuit of the air heater and of an example of implementation of means for automatic control of its operation.

 Fig. 4 is a diagram illustrating an alternative embodiment of the control means.

 Figs. 1 and 2 show that the gas air heater according to the invention comprises a carcass 1 delimiting a first compartment 2 occupied by the combustion and exchange members of the air heater and a second compartment 3 reserved for the various combustion control means .

 The compartment 2 has, on one of its vertical walls 4, an opening 5 occupied by the outlet 6 of a motor-fan 7, for example of the centrifugal type. The compartment 2 comprises, moreover, on a wall 8 opposite the wall 4, a window 9 occupied by louvers or deflector flaps 10. The compartment 2 constitutes, in a way, in its part between the opening 5 and the window 9, a circulation duct G for an air stream pulsed by the motor-fan 7 in the direction of arrow f1.

 The compartment 2 contains, in the lower part and near the wall 8, a combustion chamber 11 associated with a horizontal modulating burner 12 supplied with combustible mixture by a mixing pipe 13. The upper wall of the combustion chamber 11 communicates with a main exchanger 14 which is arranged in the sheath G to connect the combustion chamber 11 to a smoke box 15 occupying the lower part of the box 2, near the wall 4. The smoke box 15 is extended by a tube of outlet 16 which can be connected to a flue gas evacuation duct.

The main exchanger 14 is organized so as to impose on the combustion gases, coming from the chamber 11, a path in several alternating vertical directions, progressing towards the box 15 in the opposite direction to that of circulation in the direction of the arrow f1 of the air stream pulsed by the motor-fan 7. To this end, the main exchanger 14 consists of a plurality of flues 17 extending, parallel to each other, at a distance from each other, at the inside of the duct G and parallel to the direction of circulation according to the arrow f1. Each flue 17 defines a passage duct 18 delimiting a succession of segments S1, S2 .-- Sn of alternating vertical circulation between the combustion chamber 11 and the smoke box 15. Each flue 17 can advantageously consist of two plates 171 and 172 stamped to delimit together, being placed face to face and united, the segments
S2 "'- Sn. The stamped plates 171 and 172 are also produced to include conformations 19 of circulation disturbance, both combustion gases and air forced in the direction of arrow f1 by the motor-fan 7. The plates 171 and 172 are joined, at their periphery, by any suitable known means capable of ensuring an effective seal between the path of the burnt gases and that of circulation of the air stream to be heated. not shown, disturbers, also forming a secondary exchange surface, can be interposed in the intervals between the flues 17, being joined in a thermally conductive manner between the stamped plates 171 and 172 facing each other.

 The box 2 contains, moreover, an auxiliary exchanger 20, said to be condensing, having a part 20a included in the smoke box 15 and a part 20b rising inside the sheath G being disposed between the exchanger main 14 and the output of the fan motor 7. Preferably, the auxiliary exchanger 20 is of the heat pipe type including a refrigerant, such as that known under the commercial name of freon R22. The part 20a is arranged in the box 15 to be located between the connection of this box with the segments 5n of the main exchanger 14 and the outlet pipe 16. The box 15 has a low point provided with an outlet tube 21 condensates formed as shown in the operation below.

 The box 3 comprises the various operating and regulating members of the air heater, as shown schematically in FIG. 3. These various members include a turbine 25 taking air through a hole 3a which can be provided at the base of compartment 3 or concentrically with the pipe 16. The turbine 25, placed under the dependence of a thermostat, feeds the burner 12 by a mixing pipe 26 (FIG. 3) into which opens a nozzle 27 connected by a pipe 28 to a source of distribution of pressurized gas.

The operating members also comprise a pilot light 29 supplied from the same source of pressurized gas by a pipe 30 coming from an electro-valve 31. The pilot light 29, carried by the combustion chamber 11 near the burner 12 is associated with a flame detection electrode 32, as well as with an ignition electrode 33 electrically connected to a control shoe 34 placed under the dependence of a pressure switch 35 sensitive to the air pressure measured in the mixing line 26 upstream of the nozzle 27 and connected to the solenoid valve 31.

 The above organs are placed under the control of control means 36 including, in an exemplary embodiment, a speed variator 37 controlling the drive motor; turbine 25. The speed variator 37 is placed under the dependence of a regulator 38 appreciating the difference in measurement between a set temperature displayed by an adjusting member 39 and a thermometer 40 measuring the ambient temperature of the room in which the air heater is placed. The means 36 also comprise a solenoid valve 41, associated with a pressure regulator at zero and interposed on the pipe 28.

The solenoid valve 41, connected to the case 34, is controlled by a pressure sensor 42 disposed in the mixing pipe 26 upstream of the nozzle 27.

 The heater described above operates as follows.

 A difference between the ambient temperature and the set temperature, measured by the regulator 38, causes, through the variable speed drive 37, the rotation of the turbine 25 which delivers air under pressure in the pipe 26 The pressure switch 35 initiates the operating cycle of the housing 34 which supplies the flame electrode 33 and, simultaneously, opens the solenoid valve 31. If the pilot light 29 is correctly lit, the housing 34 supplies the solenoid valve 41 which delivers gas in a quantity proportional to the air pressure prevailing in the pipe 26 by the operation of the turbine 25.

 The air-gas fuel mixture is established in a homogeneous manner, to be supplied to the burner 12 at which it ignites, by means of the pilot light 29.

The combustion of the combustible mixture takes place in the chamber 11, from which the burnt gases pass through the main exchanger 14. The burnt gases give up their calories during their progression in the successive segments S1, S2 ... Sn which
n impose on them a gradual lowering of the temperature until entering the smoke box 15. The organization of the different flues results in a higher temperature inside the segments S1 and in a decrease of this temperature up to to the segments S connected to the smoke box 15. Thus, the
n air stream, flowing in the direction of arrow f1, is led to lick, successively, segments of flues of progressively increasing temperature. This ensures a gradual rise in temperature of the air, as well as a maximum intake of calories, due to the fact that, as it progresses, the heated air is caused to successively lick increasingly hot exchange surfaces. A maximum intake of calories can thus be obtained, due to the establishment of a circulation of burnt gases according to a path in the opposite direction to that of circulation of the air stream in the duct G.

 The organization of the different flues in alternating vertical circulation segments also makes it possible to impart a uniform temperature to each transverse zone of the main exchanger, also contributing to a maximum intake of calories by the air stream. circulation between Exit 6 and light 9.

 The burnt gases, introduced into the smoke box 9, are required to yield, before their evacuation by the outlet pipe 16, part of the calories which they still have, by exchange with the part 20a of the auxiliary exchanger 20. This abandonment of calories comes from the condensation of the water vapor included in the burnt gases and caused to lick the part 20a where it causes the vaporization of the refrigerant fluid; gene of the auxiliary exchanger 20. The condensation of the eju vapor is evacuated from the box 15 by the outlet 21.

 The vaporization of the refrigerant drives the latter in ascending progression in the part 20b of the auxiliary exchanger 20. Since this part 20b is located in the sheath G between the main exchanger 14 and the outlet 6, the air circulation , produced by the motor-fan 7, licks the part 20b and takes up the calories of the refrigerant by causing the condensation of the latter compelled to circulate in the direction of the part 20a.

 Thus, the latent heat, still incorporated in the combustion gases inside the smoke box 15, is recovered by the auxiliary exchanger which gives it to the stream of cold air coming from the outlet 6. Maximum recovery of the calories of combustion can thus intervene with, for main advantage, a first heating of the air stream before its passage through the main exchanger 14.

 As the difference between the ambient temperature, measured by the thermometer 40, and the set value displayed by the button 39 is reduced, the regulator 38 modulates, by the variator 37, the speed of rotation of the turbine. 25. The pressure inside the mixing pipe 26 decreases accordingly, so that the zero pressure regulator 41 is influenced to correspondingly modulate the pressure of the gas delivered by the nozzle 27.

 This results in modulated operation of the burner 12 adapting the combustion conditions of the air heater and, consequently, the conditions of subsequent exchange, depending on the contribution to be made.

 Fig. 4 illustrates an alternative embodiment in which the control means 36 involve a stepping motor 50, with two directions of rotation, supplied from the regulator 38. The stepping motor 50 controls the orientation of a flap 51 interposed on the pipe 26, between the outlet of the turbine 25 and the sensor 42, in order to modulate the air pressure as a function of the deSmarche conditions and influence, consequently, the gas flow delivered by the nozzle 27.

 As is apparent from the above, the particular structure of the air heater and, more specifically, the organization of the exchangers 14 and 20, allow maximum combustion and exchange efficiency to be obtained in a minimum volume. It thus becomes possible to produce a space-saving air heater capable of providing a durable service under the best possible conditions.

 The invention is not limited to the examples described and shown, since various modifications can be made thereto without departing from its scope.

Claims (6)

CLAIMS:  1 - Gas air heater of the type comprising a burner (12), a combustion chamber (11), a heat exchanger (14) traversed by the burnt gases from the combustion chamber and a fan motor (7) whose outlet ( 6) pulses a stream of air to be heated through a `` heat exchanger,  characterized in that:  - the burner (12) is of the modulating type and is located  associated with means (36) for controlling sound  operating under the control of a  regulator (38) appreciating the difference between the  room temperature and a temperature of  instructions,  - and the heat exchanger includes  - a main exchanger (14) imposing on the  combustion gas, between the  combustion and a smoke box (15) of  exit, a path along directions  vertical alternating progressing to  misinterpretation of that of circulation of  air stream pulsed by the fan motor,  - an auxiliary exchanger (20) said to  condensation of which a part (2tua) is  included in the smoke box (15) and of which  another part (20b) rises between  the main exchanger and the outlet of the  motor fan.  2 - Gas air heater according to claim 1, characterized in that the outlet smoke box (15) is disposed substantially at the same level as the combustion chamber (11) and in that the auxiliary exchanger (20) is of the heat pipe type.  3 - Gas air heater according to claim 1, characterized in that the main exchanger is constituted by a plurality of flues (17) arranged at a distance, parallel to each other and in the direction of circulation of the air stream pulsed by the motorcycle -fan.  4 - Gas air heater according to claim 3, characterized in that each flue (17) is constituted by stamped plates (171, 172) joined and joined face to face and defining a path of passage (18) delimited by a succession of segments (S) of alternating vertical circulations between the combustion chamber and the smoke box.  5 - Gas air heater according to claim 1, characterized in that the burner control means comprise  - a variable speed turbine (25) supplying the  air burner by a mixing pipe (26),  - a speed variator (37) controlled by the  regulator (38) and controlling the turbine,  - a nozzle (27) delivering gas under pressure into  the mixing line between the turbine and the  burner,  - and a regulator (41) placed on the power supply  nozzle and sensitive to air pressure  delivered by the turbine in the line of  mixing upstream of the nozzle.  6 - Gas air heater according to claim 1, characterized in that the burner control means comprise a stepping motor (50) placed under the control of the regulator (38) and responsible for controlling the position of a shutter (51 ) disposed on the mixing pipe (26) between the turbine outlet (25) and a sensor (42) influencing the regulator (41).