DE3608698A1 - BURNER BOILER UNIT - Google Patents

Description

The invention relates to a burner / boiler unit with a mixing device arranged at one end of a tubular combustion chamber.
a fuel feed pump and a compressed air source, which are connected to the mixing device,
and a heat exchanger surrounding the combustion chamber.

In a known oil burner boiler unit (DE-PS 30 20 398) the mixing device contains an atomizer exercise device having a flat cutting edge, which creates a flat mixture jet, the Flame in the combustion chamber by deflecting one Baffle plate is stabilized. This well-known unit is able on the one hand, especially small amounts of oil low pollutant processing and a broad rule range of heating power, but it tends to on the other hand, if the air pressure is too low for storage  oil coke. It also turned out to be difficult pointed the ignition of the flame with a high voltage arc.

Based on this state of the art, the Er the task underlying a burner-boiler Create unit where the heating power is within a large control range is changeable and the one low-pollution combustion enables.

To achieve this object, according to the invention,
that the fuel feed pump and the compressed air source are synchronously driven displacement pumps from a common speed-controllable drive,
that the pressure of the compressed air source is greater than about 15 mbar
and that the part of the combustion chamber facing the mixing device has a jacket cooled by the water of the heat exchanger, while the part facing away from the mixing device is provided with a heat-insulating jacket.

In the burner-boiler unit according to the invention the combustion air is proportionate high pressure supplied, proportionally to the Fuel. The pressure at which the air is supplied is preferably between 20 and 200 mbar. This High pressure usually means moving away from the usual used fan wheels, in which the by far largest Part of the drive energy is lost. A crowding out gerpump also delivers the required high pressure high efficiency. This pressure is in the mix device implemented, but not used. The  A large part of the pressure energy comes from the Ge mixing flow into the combustion chamber to do mixing work there afford to. This reduces pollutant formation and that required combustion chamber volume is reduced.

The swirling mixed stream entering the combustion chamber generates a flame-stabilizing recirculation of hot flue gases without the risk of residue deposits and also allows the combustion to be ignited by an electric arc in the central or external backflow area. As a result of the good high pressure atomization and mixing, hot combustion chamber walls in the front area of the combustion chamber can be dispensed with. The water cooling of the jacket in the first part of the combustion chamber (primary zone) lowers the gas temperature, which in conjunction with the short dwell time of the gas in the highly loaded primary zone results in a reduction in nitrogen oxide formation. In the rear part of the combustion chamber (secondary zone), the remaining reaction temperature is maintained by the heat-insulating jacket in order to ensure the combustion of the carbon monoxide CO to carbon dioxide CO ₂ .

There can be a ring between the two parts of the combustion chamber shaped constriction may be provided which the recircu lation in the primary zone and mixing in the Secondary zone supported.

By using a swirl nozzle in the mixer device becomes a rotationally symmetrical air flow atomization reached and a swirling mixture electricity generated. This has the advantage of oil as a fuel part of a fine atomization, a good mixing  and a relatively homogeneous fuel distribution. By the swirl stabilization of the flame eliminates the ver use of baffle plates.

According to a preferred development of the invention provided that the flow path of the flue gases in Heat exchanger is so narrow that at least in the top Speed range of the drive a turbulent flow occurs in this flow path. In a turbulent flow through the high-performance heat exchanger Heat transfer coefficient with increasing flow considerably stronger than with laminar heat exchange, i.e. the heat exchanger needs at stei gender heating output a smaller increase in its Heat exchange surfaces. With a fixed heat exchanger the gas outlet temperature increases with high heating performance less. By narrowing the flow path the flue gases adapts to the heat exchanger performance of the Output of the burner in a wide range, so that there is no need for heat exchange to enlarge areas. In the entire performance range of Burner can with small changes in the exhaust gas temperature with a fixed heat exchanger.

Up to a control range of the heating output of approx 1: 2.5 can with fixed airflow nozzle in the mixer device to be worked. For much larger ones It is appropriate to use control ranges that the system allows moderate to change the cross section of the swirl nozzle can to the required high air speed to get without generating too high air pressure have to. According to a development of the invention provided that the cross section of the swirl nozzle in Ab dependence on the heating power is changed, and  although preferably depending on the pressure of the Compressed air source. The greater this air pressure, the more the flow cross-section at the swirl nozzle becomes larger made. In this way, the swirl nozzle is on the the required heating output is coordinated. With a Such a variable swirl nozzle can be used in the control range the heating output can be increased up to about 1:10.

The invention is also suitable for a burner Boiler unit with gas operation. While with the oil operated the swirl generating mixing device both for Atomization of the heating oil as well as for mixture formation and serves to stabilize the flame, does not apply to one Gas burner the atomizing effect. The advantages of Pollutant reduction and speed-dependent burning Substance-air composite regulation will be maintained. At a gas burner is conveniently the two Combustion pumps combined into a single unit summarize, the housing of this unit by a Partition wall is divided, which of a the Connecting the rotor of the two positive displacement pumps Intermediate shaft is penetrated. Compound displacement ger blower means compared to gas blower burners common radial fans an extra run wall, but already with a non-performance rule th single-stage burner through various savings more than is weighed. The volumetric gas metering depends only slightly on the gas pressure in the gas network, so that no pressure regulator is required. A pressure switch is also not necessary because the Regulation only fails if the compound fan fails. In such a case, safety devices switch the gas supply because of the lack of ver combustion air or the power supply. Especially  it is advantageous that a speed control only for the Compound displacement fan drive motor required Lich and that complex mixing devices with Volume control is not required.

The usual gas-blown burners stick with everyone Turn off the fittings and lines between the Solenoid valve and the mixing device with residual gas fills, which subsequently seeps into the combustion chamber. At the device according to the invention can infiltrate of residual gas into the combustion chamber can be avoided by a small check valve between the inlets of Air blower and gas blower is placed. Once the gas supply is shut off, the gas blower sucks over the Check valve air to remove the residual gas from the lei rinsing. Even if the power supply fails supply network is caused by the overrun of the drive motor still flushing out gas from the gas line.

In the following with reference to the drawing gene embodiments of the invention explained in more detail.

Show it:

Fig. 1 power is a longitudinal section through a burner boiler unit with a controllable heater,

Fig. 2 shows a section along the line II-II of Fig. 1,

Fig. 3 is a section similar to Fig. 2 to that in an embodiment in which the Strö flow cross-section of the swirl nozzle in Depending ness is changed by air pressure,

Fig. 4 shows a longitudinal section through a swirl air stromzerstäuber with central oil application of a pressure nozzle

Fig. 5 shows a longitudinal section through another swirl Luftstromzerstäuber with annular koni shear Zerstäubungsschneide,

Fig. 6 shows a longitudinal section through a further swirl air flow generator with the pressure nozzle, but without Zerstäubungsschneide,

Fig. 7 is a longitudinal section through another form of imple mentation of the swirl air flow generator with pressure nozzle and

Fig. 8 is a longitudinal section through a gas burner boiler unit.

The controllable burner-heating boiler unit shown in Fig. 1 has an electric motor 10 , the speed of which is controlled by a speed control unit 11 . The output shaft of the electric motor 10 drives a compressed air displacement pump 12 and a heating oil displacement pump 13 . The two pumps 12 and 13 are positive displacement pumps, ie their delivery rate is proportional to the drive speed. Roots pumps, gear pumps or piston pumps are suitable for this. The pressure lines of the two displacement pumps 12 and 13 lead to the mixing device 14 designed as an atomizing device.

The mixing device 14 is accommodated in the nozzle housing 15 , which at the same time forms the end of the combustion chamber 16 . The tubular nozzle housing 15 has a combustion chamber 16 on the combustion chamber 16 closing cover wall 17 and is sealed at the opposite (outer) end with a cover 18 . An oil supply line 19 designed as a capillary line is sealingly passed through the cover 18 . The oil supply line 19 leads through the inside of the nozzle housing 15 arranged nozzle body 20 and exits at the front side. Around the outlet pipe 21 are numerous rich swirl-generating air-guiding elements in the form of wings 23 are arranged on the flange-like end wall 22 of the nozzle body. These vanes 23 are shown in FIG. 2 inclined in the circumferential direction and they ver jüngen down to the inner end. The wings 23 be be channels 24 through which the radially inflowing air receives a peripheral component. Each of the channels 24 decreases in cross section towards its inner end, so that the air is increasingly accelerated in each channel 24 .

The wings 23 are arranged between the end wall 22 and a plate 25 running parallel to this end wall. The end wall of the plate 25 facing away from the vanes 23 forms the boundary wall of a further swirl nozzle with vanes 26 which are attached to the end side of a further plate 27 . The plate 27 ver runs parallel to the plate 25 and their wings 26 are formed and arranged in the same way as the wings 23 of the plate 22nd

The air flowing in through the inlet 28 laterally into the nozzle housing 15 is distributed inside the nozzle housing and flows radially into the channels 24 between the vanes 23 and into the corresponding channels between the vanes 26 . The wings 23 and 26 give the air a swirl, ie a circular motion.

The plate 25 is annular and its lower edge has the shape of an annular cutting edge 29 which projects axially in the direction of flow and tapers conically towards the end. The inner edge of the annular plate 27 is also bent axially in the direction of flow and it forms a conical ring 30 which surrounds the cutting edge 29 at a radial distance.

The heating oil emerging through the tube 21 is caught by the rotating air stream and sprayed onto the inside of the cutting edge 29 . The cutting edge 29 is flowed around on both sides by rotating and axially moving air flows, which tear off the heating oil film from the circular, sharp tip of the cutting edge 29 and distribute it finely and evenly. The fuel oil droplets mix intimately with the combustion air and together with this enter the tubular combustion chamber 16 . As a result of the swirl injection under high pressure 16 annular flow rollers arise in the front part 16 a of the combustion chamber, in which part of the mixture flow is returned and which rotate around the longitudinal axis. To ignite the mixture in part 16 a of the combustion chamber, an electrode 31 is arranged. Another electrode 31 'is used for flame monitoring. After ignition, part 16 a of the combustion chamber 16 creates a stable blue flame which essentially fills part 16 a and continues into the rear part 16 b .

The part 16 a forms the primary combustion zone, which is separated from the part 16 b by a ring 32 , which forms a constriction constriction 33 . The peripheral wall of a part 16 b , which forms the secondary combustion zone, is provided with a heat-insulating lining 34 and thereby protected against cooling by the heat exchanger.

The heat exchanger 35 surrounds the combustion chamber 16 in a ring shape. The path of the water that is supplied to the heat exchanger 35 is shown in solid lines in FIG. 1, while the path of the combustion gases is shown in dashed lines.

The water flows axially from the inlet 36 through the outer annular space 37 until it is deflected at the end of this outer annular space 37 on the burner side and passes into the central annular cavity 38 . The water flows through this in countercurrent to the cavity 37 . The end of the central cavity 38 facing away from the atomizing and mixing device 14 is connected via bent pipe pieces 39 to the inner annular cavity 40 which is flowed through in the opposite direction to the central cavity 38 . The outlet 41 for the heated water is arranged near the nozzle-side end of the central cavity 40 .

The inner boundary wall of the inner cavity 40 is formed by the tube 42 , which is the wall of the combustion chamber 16 . The outer wall of the inner cavity 40 consists of the tube 43 . The central cavity 38 is delimited by the tubes 44 and 45 and the outer cavity 37 by the tubes 46 and 47 . All tubes 42 to 47 are arranged coaxially to one another and surround the combustion chamber 16 .

At the part 16 b of the combustion chamber 16 , the collection space 48 connects, through which the fuel gases in the annular gap 49 pass between the tubes 43 and 44 . The annular gap 49 is flowed through in the opposite direction to the combustion chamber 16 . The fuel gases are then redirected again in order to get into the annular space 50 between the tubes 45 and 46 . The outlet end of the annular space 50 is located at the end of the heat exchanger 35 facing away from the mixing device 14 . From there, the combustion gases enter the outlet 51 , which is separated from the collecting chamber 48 by a heat-insulated wall 52 , into a chimney.

The swirling into the combustion chamber 16 Ge mixed flow generates in the first part 16 a , which is water-cooled through the wall 42 , both a central and a peripheral heating gas recirculation, which stabilize the blue, low-emission heating oil flame. In the second part 16 b burns mainly carbon monoxide CO still contained in the heating gas to carbon dioxide CO ₂ . The part 16 b is protected by the heat insulating liner 34 against further cooling. After leaving the secondary combustion zone, which also includes the deflection space 48 , the fuel gas has largely reacted.

The annular spaces 49 and 50 have a relatively small radial width, so that turbulence can be generated by wall friction. Such turbulence occurs in particular when the motor 10 runs at the upper speed range and delivers a large amount of air when the heating power is high. Since the heat transfer of the heat exchanger is improved by a turbulent flow, the heat exchanger capacity adapts to a certain extent to the heating capacity of the burner.

By the above-described arrangement of the wings 23 in connection with the annular blade 29 , a swirl nozzle 53 is formed, which the mixture flow a circumferential and an axial movement component he shares.

If a large control range of the heating power is required, it may be expedient to change the flow cross section of the swirl nozzle 53 so that the pressure loss caused by the swirl nozzle does not become too large at high throughput or so that the atomization does not become too bad at low throughput.

Fig. 3 shows a variant to change the flow cross section of the mixing device for changing the swirl component. For this purpose, the wings 23 are not rigidly attached to the end wall 22 , but each wing 23 is pivotally mounted on the central plate 25 on an axis 55 . Pins 56 protrude from the upper plate 22 , each of which projects into an elongated hole 57 of a wing 23 . The middle plate 25 is rotatably supported, and by rotating this plate 25 , the angle of attack of the wings mounted on it can be changed in the manner shown in FIG. 3. The plate 25 is rotated by a rod 58 which is connected to the periphery of the plate 25 via a joint 59 . The rod 58 protrudes through a tube 60 into a housing 61 which has a ventilation opening 62 . In the housing 61 there is a bellows 63 , which is sealingly connected to the end of the tube 60 . The pressure prevailing in the interior of the nozzle housing 15 passes through the tube 60 into the interior of the bellows 63 . The greater this pressure, the further the rod 58 is drawn into the housing 61 . The bellows 63 also acts as a spring, which strives to push the rod 58 out of the housing 61 . By the tangentially to the plate 25 engaging rod 58 , the plate 25 is rotated in dependence on the prevailing pressure in the nozzle housing 15 , whereby the wings 23 are pivoted about their axes 55 . The greater the pressure in the nozzle housing 15 , the larger the cross section of the channels 24 delimited by the wings 23 , ie the more the tip of a wing 23 is moved away from the adjacent wing.

Referring to Fig. 3, the possibility has been explained, 53 change the swirl-producing section of the swirl nozzle to ver. Alternatively or additionally, there is the possibility of changing the axial component of the swirl nozzle 53 , for example by means of a cone which can be moved in the nozzle opening as a function of pressure.

Fig. 4 also shows a pressed sheet metal in the swirl nozzle 53rd In the swirl chamber 80 , the heating oil tube 21 described above can also be replaced by a spray nozzle 70 which is connected to the supply line 19 . The air supplied through the inlet 28 flows between fixed vanes 71 which, like the vanes 23 and 26 of the first embodiment, are inclined to impart a circumferential component to the air flowing radially inwards from the outside. The wings 71 are partially covered on their top by a plate 72 , which leaves an outer edge slot 73 free, through which the air between the wings 71 can ge long. The outer edge of the annular cutting edge 29 is attached to the inner ends of the wings 71 , in fact halfway up these wings, so that the cutting edge 29 is coated on both its underside and on its top by the rotating air stream. The wings 71 rest on the end wall 17 of the combustion chamber. This end wall also carries the electrodes 31 for igniting the flame.

The spray mist emerging from the spray nozzle 70 is sprayed onto the inside of the annular blade 29 and entrained by the rotating air stream. The resulting fine oil film on the blade 29 is carried along by the two air currents at the tear-off edge of the blade and is introduced into the combustion chamber 16 as a rotating spray cone.

The embodiment of FIG. 5 is largely the same as that of FIG. 4, but there is no separate spray nozzle. Rather, the feed line 19 leads into the interior of the edge region of the blade 29 . Here, there is an annular cavity 64 , which is connected to the inside of the blade 29 by means of microslots 75 . The oil passes through the annular space 64 to the inside of the blade 29 and is entrained here by the rotating and axially moving air stream.

The embodiment of Fig. 6 is similar to that of Fig. 4, except for the fact that there is no cutting edge. The spray nozzle works as a swirl pressure nozzle with air support by the air flowing between the vanes 71 .

The mixing and atomizing device 14 of FIG. 7 largely corresponds to that of FIG. 1. The tube 21 projects through an opening in the end wall 22 and behind this there is the plate 25 with the annular conical cutting edge 29 . Behind the plate 25 , the plate 27 is arranged with the likewise annular conical cutting edge 29 a , which forms an annular gap with the cutting edge 29 . The package from the end wall 22 and the plates 25 and 27 contains tangential bores 80 which lead from the nozzle housing 15 into the swirl nozzle 14 . The bores 80 are located in the end wall 22 or the plate 25 , so that the air flowing from these bores into the nozzle rotates along the inside of the cutting edge 29 . The Bohrun gene 81 are located on the underside of the plate 25 or the top of the plate 27 , so that the air flowing in through these holes 81 flows rotatingly along the outside of the cutting edge 29 . Both air currents have the same direction of rotation.

Fig. 8 shows a gas burner-boiler unit, only the primary combustion zone 16 a is shown of the combustion chamber, which is limited by the ring 32 , which forms the constriction constriction 33 . The burner is essentially constructed in the same way as the oil burners described above, so that the differences from the oil burners are mainly explained in the fol lowing.

The mixing device 14 consists of the swirl nozzle 53 which has inclined vanes 71 for the combustion air and an axial nozzle opening 29 behind it. The inner ends of the wings 71 are limited by the underside of the conical cover member 85 . Above the cover member 85 is the guide cone 86 formed as an inner cone, which, together with the cover member 85, forms a conical passage which leads from the axial bore 88 to the outer regions of the vanes 71 . Through the cover member 85 leads the gas supply line 87 , the outlet of which is located in the middle of the underside of the cover member 85 , so that the fuel gas axially enters the swirl nozzle 53 , while the air enters radially and receives a tangential component through the wing 71 .

The double displacement blower 89 consists of the air displacement pump 12 and the fuel gas displacement pump 13 . The positive displacement 89 is mounted on the nozzle housing 15 and provides air-drying the Burn through the bore 88 and via the gas feed line 87, the fuel gas to the mixing device fourteenth In the present case, the displacement pumps 12 and 13 consist of gear pumps. These pumps are shown in a section that runs ver in the central plane between the two pump gears, so that you can only see the idler gear 90 and 91 , which is not driven from the outside. The axes of the pump gearwheels run at right angles to the longitudinal axis of the swirl nozzle 53 . The pump gear 90 of the air displacement pump is mounted in the wall 92 and the intermediate wall 93 of the pump housing, and the pump gear 91 of the gas displacement pump 13 is mounted in the intermediate wall 93 and the housing wall 96 . The axes of the indirectly driven pump gears 90 and 91 ver run on a common line, as well as the axes of the (not shown) directly driven pump gears also run on a common line. It is also possible to manufacture both pump gear wheels 90 , 91 from a single block which is only supported in the walls 92 and 93 or 92 and 96 . In the same way, the directly driven pump gears can consist of a common block that is only stored in two walls.

The air displacement pump 12 draws the combustion air from the outside via a silencer 97 and the inlet pipe 98 . A collecting space 99 is located between the displacement fan 12 and the bore 88 . The fuel gas is pressed out of the gas line through a filter 100 and two solenoid valves 101 into the suction chamber 102 and conveyed through the displacement fan 13 into the collecting chamber 103 . The gas line 87 leads from the collecting space 103 to the mixing device 14 . As long as the line gas pressure is higher than the combustion chamber pressure, the gas pressure drives the displacement pump 13 , which thus works as a motor, which partially relieves the electric motor driving the two displacement pumps 12 and 13 .

Between the air inlet 98 and the suction chamber 102 there is a check valve 104 , which can let air through from the air inlet 98 to the suction chamber 102 , but which cannot let gas pass in the opposite direction. The check valve 104 is kept closed by the gas pressure ge as long as the solenoid valves 101 are open. If the gas is shut off, the back opens check valve by the suction effect of the displacement blower 13 so that air is drawn into the positive displacement 13 while residual gas from the gas positive displacement 13 and the gas line is flushed 87 and still burns in the combustion chamber.

Claims (9)

1. burner-boiler unit with a mixing device ( 14 ) arranged at one end of a tubular combustion chamber ( 16 ),
a fuel feed pump ( 13 ) and a compressed air source ( 12 ) which are connected to the mixing device ( 14 ),
and a heat exchanger ( 35 ) surrounding the combustion chamber ( 16 ), characterized in that the fuel feed pump ( 13 ) and the compressed air source ( 12 ) are synchronously driven displacement pumps by a common speed-controllable drive ( 10 ),
that the pressure of the compressed air source ( 12 ) is greater than about 15 mbar
and that of the mixing device (14) to facing portion (16 a) of the combustion chamber (16) has a cooled by the water of the heat exchanger (35) jacket, while the (14) facing away part is provided to the mixer (16 b) having a heat-insulating mantle is. 2. Burner-boiler unit according to claim 1, characterized in that between the two parts ( 16 a , 16 b ) of the combustion chamber ( 16 ) an annular constriction ( 33 ) is provided. 3. burner-boiler unit according to claim 1 or 2, characterized in that the flow path of the combustion gases in the heat exchanger ( 35 ) is so narrow that at least in the upper speed range of the drive ( 10 ) a turbulent flow in this flow path ( 49 , 50 ) occurs. 4. Burner-boiler unit according to one of claims 1 to 3, characterized in that the mixing device ( 14 ) has a swirl nozzle ( 53 ). 5. burner-boiler unit according to claim 4 for oil as fuel, characterized in that the mixing device ( 14 ) is an atomizing device which has a conical annular cutting edge ( 29 ) that an application device for evenly distributing the oil over a surface the cutting edge ( 29 ) is provided and that air-guiding elements ent the ent air with a swirl on at least one of the two cutting surfaces ent. 6. Burner-boiler unit according to claim 5, characterized in that the air-guiding ele elements are wings ( 23 , 26 ), each of which is pivotable about an axis ( 55 ) such that the distance of its tip from the neighboring Wings changed. 7. burner-boiler unit according to claim 6, characterized in that the control of the wing ( 23 , 26 ) by a pneumatic actuator ( 58 , 63 ) in dependence on the form of the mixing device ( 14 ). 8. Burner-boiler unit according to one of claims 1 to 7, characterized in that the two positive displacement pumps ( 12 , 13 ) are combined to form a double pump which has two pairs of rotors which are firmly connected to one another, each with two rotors of the two pumps are arranged with their axes along a common straight line. 9. burner-boiler unit according to one of the preceding claims for gas as fuel, characterized in that a leading to the air displacement pump ( 12 ) leading air line ( 98 ) with a leading to the gas displacement pump ( 13 ) gas line Check valve ( 104 ) is connected, which opens in the direction of the air line ( 98 ) to the gas line.