CENTRAL HEATING BOILER WITH A SECOND BURNER

Abstract: For the improving of the efficiency of an incinerator and for the reduction of the pollution the flue gases are led through a second burner (14, 23) placed at the bottom of the combustion chamber (16, 17) of the boiler (1). The second burner consists of a flue duct with a catalyst (3, 5, 21), where secundary air is admitted through a pipe (4, 19). A grate (18) in a base combustion boiler may be shaped like a pipe or a pipe encircling member, the pipe admitting the secundary air. When the grate (18) is glowing, the flue gases and the secundary air are heated, and in presence of the catalyst (21) the gases are ignited and burned completely. In a combustion boiler that burns the fuel completely two catalysts may be used, one of which (5) being placed at the intake of the secundary air, the other (3) being placed after the former in the direction of flow of the flue gases. In practice catalysts of Al<u2>uO<u3>u or porous platinum have proved suitable.

Description: C E N T R A L H ' E A T I G 3 0 I L Ε R W I T H A S E C O N D B U R N E R The invention relates to a central heating boiler . consisting of a combustion chamber which is surround¬ ed by a water chamber and with a firing opening and an outlet pipe for the flue gases ■ and admission of primary air. Incinerators of this kind are used for heating pur¬ poses, where solid as well as liquid " fuel as e.g. bales of straw, wood, peat, coke, and oil can be burned. The problem of these incinerators is that the most eco- * ■ nomic and complete combustion cannot be achieved. This means that the flue gases" contain partly uriburned gases and further ' that they contain air contaminat¬ ing substances. In a combustion boiler the flue gases thus have a content of carbonmonoxide of up to percentage by volume and a content -of particles as e.g. dust and soot of up to 6000 mg/πr dry flue gases at 12 percen¬ tage by volume carbon monoxide. The object of the invention is to meet these short- comings, and this is achieved when at the bottom of the combustion chamber a second burner is placed with a channel running into the outlet pipe, and where at least one catalyst is placed in the channel, to which secundary air is supplied through a pipe. Thus an effective second combustion of the flue gases . that are made in the combustion chamber is achieved, so that these are burned completely .in order to obtain ' the optimum heating eco ony, and that the content of contaminating particles is reduced as much as possible. The placing of the second burner at the bottom of the combustion chamber ensures the best utilization " c.f the glowing heat of the fuel, the flue gases being heated.in the second burner ' to at least the .'ignition point. Furthermore the- lue duct secures that the flue gases stay in the second burner enough time for • obtaining the necessary temperature and thermal reaction time. The catalyst causes the ignition point of the flue gases to be reduced so that the gases through admission of secundary air are ignited and burned shortly after lighting-the boiler. When supplying the boiler with a grate, as mentioned . in claim 2, and placing the pipe for admission of secundary air near this grate, ' an e fective hea ' ting . of the pipe and thus of the air, too, is achieved * so that the flue gases are not cooled by the secunda¬ ry air. When shaping the grate encircling the pipe, cmp. claim 3a an effective glowing of the grate and thus radiant heat to the pipe and the air through this pipe is achieved. When using the channel of claim with two catalysts equally good operation results of a combustion boiler, which burnes the fuel completely,, can be obtained. The use of the cone of claim 5 secures a good mixing of the secundary air and the flue gases. Finally it has proved to be appropriate to use Al-O, Besides there is admission of .primary air. from a blower 10 through a channel with a dividing plate 11 leading the primary air to a longitudinal pipe 7 at the bottom, which pipe is supplied with a suitable number of Outlet holes. Above this primary combustion air pipe 7 the second burner 14 is mounted. In this way the primary com¬ bustion air is distributed quite correctly by means of the second burner Ik . which leads the air evenly out into the combustion chamber lβ. c The second burner forms a part of a flue ' duct 8, which leads from the back of the combustion chamber Iβ " .; . -. through the middle and down to the back of a cylin¬ drical pipe with a horinzontally mounted dividing plate 2, which extends from the back to a place near the front. Thus a channel 8 is made that first leads • the flue gases forward, turns them, and then leads them under the dividing plate 2 back into the flue duct 8..to ' a -vertical outlet channel with a flow damping plate 12 and out through the outlet pipe 9« In the flue duct 8 under the dividing plate 2 a secύn- dary air pipe is placed. It is connected to the upper part of the air channel and extends to-;a ' suitable point down the channel 8, e.g. half the way. The pipe 4 is closed at the end, but at the front end supplied with a suitable outlet for the necessary and sufficient secundary air, which outlet is mainly com¬ posed by a rather small number of small holes 15• Four 3 mm holes have proved to be appropriate of an embodiment. Round this pipe 4 a catalyst 5 of A ~ ° ^ s placed for I or porous platinum as catalysts, as mentioned in claim β , as the presence of .these substances reduces the ignition point of the flue gases. The invention will be explained in detail with reference to the drawing, where Fig. 1 shows a sectional view through a combustion boiler with a second burner, seen in the direction I-I in Fig. 2, ' Fig. 2 shows a sectional view of the boiler, seen in the direction II-II in Fig. 1, P g- 3 shows a sectional view through a base combustion boiler with a . second burner, " seen in the άirec- tion III-I I in Fig. 4, and Fig. 4 shows a sectional view of the boiler, seen in the direction IV-IV in Fig. 3. Fig. 1 and 2 show an example of a combustion boiler.1, ' which burnes the fuel all up, and which can be suppli¬ ed with a second burner. The boiler itself consists of an outer insulated hood encircling a water chamber, which encirclesthe very combustion chamber i β . At the front of the boiler a firing opening .and an air intake are placed, and at the back of the boiler the outlet pipe 9 for the flue gases ends. In this embodiment the combustion chamber 16 is cylin¬ drical and lined with fireproof ceramic material 13 at the lower half, protecting the boiler and heat insu¬ lating. 1 This air is led through a pipe 20 with outlet openings arranged below the grate 18. The number, and placing of .the holes are chosen considering the desired amount of air. Thus under the second burner 23 and 5 the outlet pipe 24 longitudinal slots are extending in the pipe 20 for the increase of outflowing air. At the bottom, besides, there is an intake for the secundary air, which is led through a metal pipe 19 10 extending through the grate 18 into the second burner and which pipe ends inside the burner. Here the cata¬ lyst 21 is placed. It is shaped like a ring encircl¬ ing the outlet for the secundary air. 15 During the combustion the grate is heated, to becoming red-hot, and " he secundary air in the pipe 19 and'.the . flue ' gases are ' :heated simultaneously, when the gases pass the grate a s on their way into he second burn¬ er 23. When heated secundary air is led to the heated 20 flue gases in presence of the catalyst, they are ig¬ nited and burned completely. A base combustion boiler of this type has been tested according to the standards of the West German regula- 25. tions DIN 4702 leaf 1 and 2. The test showed that a content of carbon dioxide in the flue gases of 8.2* and a content of carbon mono¬ xide of 0.l£ was measured by a temperature of the 0 flue . gases of 204°C. The emission was under - 300 mg/m , and the plume of smoke was measured to No. 0-1 according to Ringelmann. All claims according to the DIN 4702 leaf 1 and 2 5 was then fulfilled. the -.reducing of the ignition point of the carbon mon¬ oxide gases. The gases are thus led between the cata¬ lyst and the pipe. Instead of 1 2 0 ^ porous platinum can be used, though other suitable materials may be ' used for this purpose. After the pipe 4 there is placed a cone 6 giving turbulence and thus an optimum mixing of secundary air and flue gases. Furthermore another catalyst 3 is placed in the last part of the flue duct 8. The flue gases are thus led into the flue duct from the front and are lighted in the flue channel 8 by means of a combination of heat from the glowing heat and admission of secundary air. The catalysts reduce the ignition point, and the gases burn • • * completely. Fig. " -3 and 4 ' show an * 'example of ab.ase combustion boiler with a second burner. The boiler is supplied with a grate 18 at the bottom of the combustion chamber 17, which grate (18) consists .oϊ shaped grate bars, as it occurs from the sectional view of Fig. 4. These grate bars are fastened to supporting rings for the formation of a hollow grate or en encircling grate. At the front the grate is closed by a plate 22. At the back the grate is connected to the second bur¬ ner 23, which comprises a channel connecting the inner part of the grate to the outlet pipe 24 at the back in the combustion chamber. Through the front plate of the boiler at the middle an upper air intake for primary air extends, and at the bottom a lovrer intake for primary air is placed.

Claims: C L A I M S 1. Central heating boiler, consisting of a combu¬ stion chamber surrounded by a water chamber and with a firing " opening ' and an outlet pipe for the flue gases and admission of primary air, c h r a c t e r i z e d i n that a second burner (14, 23) is placed at the bottom of the combustion chamber (16, 17) with a channel running into the outlet pipe - (9j 24), and where at least one catalyst (3, 5. 21) is placed in the channel, to which secundary air is led through a pipe (4, 19)i 2. Central heating boiler according to claim 1. c h a r a c t e r i z e d i n that a grate (18) is placed in front of the second burner (23) and runs across the bottom of the combustion chamber. (17), and under which the pipe (19) is mounted. 3. Central heating boiler according to claim 1, c h a r a c t e r i z e d i n that the grate (18) is shaped encircling the pipe (19). 4. Central heating boiler according to claim 1, c h a r a c t e r i z e d i n that a catalyst (5) is placed in the area for admission of secundary air from the pipe (4), another catalyst (3) being placed after the former (5) in the direction of flow of the flue gases. 5. Central heating boiler according to claim 4, c h a r a c t e r i z e d i n that a cone ( β ) is placed after the pipe (4) in the direction of flow of the flue gases. 6. Central he.at.ing boiler according ' to claims 1 - 5 * c h a r a c t e r i z e d i n that' the catalyst (3, 5, 21) contains Al^O, or porous platinum.

Inventors: SORENSEN JENS C
Applicants: PASSAT 81 AS, SORENSEN JENS C
Application year: 1981
Main classification: F23C6
IPC codes: F23C6, F23C13, F24H1, F24H9