HEAT STORAGE DEVICE FOR OIL OR GAS FURNACES

Abstract: In order to improve the efficiency of an ordinary household gas or oil furnace, a heat storage device is placed directly in the combustion chamber of the boiler. The device (4) is made of cast iron and is provided with a support base (5) making the device take a slightly rewardly inclining position in the combustion chamber, and a holder or lifting device (1) at the upper end of the device. The device is placed directly in the flame at a distance of 5-15 cm from the burner head so that the device reaches a temperature of 150-350<o>C. The highest degree of efficiency is obtained during the weak heating seasons, i.e. spring, summer, and autumn, when a doubling of the dead periods of the furnace can be obtained.

Description: HEAT STORAGE DEVICE FOR OIL OR GAS FURNACES The invention relates to a heat storage ' device for an oil or gas furnace. Ordinary household oil or gas furnaces normally operate as start/stop furnaces with dead periods. During the periods when the furnace • is operating, the heat emitted from the " burner will ac- * - cumulate in the walls of the boiler and in the amount of water in the boiler. When the amount of heat accu¬ mulated during the dead periods of the furnace is distributed in the heating plant or has disappeared as losses e.g. due to natural draught from the chim¬ ney, the boiler thermostat of the furnace will start the furnace so as to produce more heat. It is possible to extend the dead periods by placing an additional heat storage unit in or by the boiler. From the specification to US patent no..2,858,781 there is known a heat storage unit to.be placed in a heater furnace where said units consist of a contain¬ er wherein there is placed a suitable heat retaining medium such as small pieces of iron, sand, concrete or similar substances that can stand the temperatures. The heat storage unit according to the American pat¬ ent is used in a hot-air central heating plant to equalize the hot-air supply. As disclosed in claim 1, the heat storage device ac¬ cording to the present invention is adapted to be placed directly in the combustion chamber of the furnace so that it touches the flame, and the device is designed as a solid metal block. It is thus pos¬ sible to ' use the heat storage device very efficiently since it takes up heat directly from the heat source, TUKEAT OMPI ie. the furnace flame, so that the storage device reaches a high temperature and thus a large heat content. By producing the heat storage device of cast iron as disclosed in claim 2, there is obtained a metal device made of a material not forming oxide scale. Many other types of metal form oxide scale when strongly heated, said oxide scale forming an insula- ting layer * on the device. The device is designed as a body of revolution as disclosed in claim 3. It is thereby possible for the flame to circumvent the device and therefore the device will not impede the flow in the boiler cham¬ ber. On the contrary there is obtained an improved heat emission effect to the boiler wall as the flame is forced closer towards the boiler wall. To place the heat storage device in a simple manner in the combustion chamber of a boiler, it can be designed with a support base as disclosed in claim 4. The support base moreover forms part of the heat storage device and the strong base means that the device will stand securely and firmly in the furnace. It is also possible to provide a device not having a support base with support legs welded thereon as disclosed in claim 5 so that by using different lenghts of legs it is possible in a simple manner to adopt the device to different types of boilers. It may be practical to provide the up-turned part of the device with a lifting device so that it is easier to take out and to place the quite heavy device in the combustion chamber of the boiler. The support fcase of the device can. be designed as dis¬ closed in claim 7, whereby the device shaped as a body of revolution can be positioned so as to incline slightly rearwardly away from the flame. Improved flow conditions in the combustion chamber are there¬ by obtained. The invention will be further described in the fol¬ lowing with reference to the drawings ' , wherein Fig. 1 is a cross-section of a heat storage device according to the invention made of cast iron and having an inclining support base, Fig. 2 is a cross-section of. a heat storage device according to the invention made of cast iron having an inclining support base and a lifting device on the up¬ turned part, and Fig. 3 is a cross-section of a heat storage device according to the invention being substantially egg-shaped and having support legs and a lifting hook welded thereon. Fig. 1 of the drawings shows a heat storage device 4 off cast iron weighing about 12 kg. The device is pro¬ vided with a base 5 moulded at the same time as the device and forming an integral part, thereof. Fig. 2 shows a similar device but provided with a carrying or lifting device 1 at the top so that it is easier O to catch hold of the device e.g. when it is to be placed in the combustion chamber of a. boiler. The device shown in Fig. 2 weighs from about 12 kg to about 20 kg. Fig. 3 shows a somewhat different embodiment of the invention, the device having the shape of a flattened ball or an egg. The device is provided with three support legs 3 and an eye 2 welded thereon, by which eye 2 ' it is possible to lift the device. This embodi¬ ment weighs about 23 kg and has a maximum diameter of about 18 cm and a minimum diameter of about iβ cm. The heat storage device according to the invention is placed directly in the combustion chamber of the boiler so that the device stands at a distance of 5-15 cm from the burner head. The device has the shape of a body of revolution, eg. ball-shaped, flattened ball-shaped, egg-shaped or a similar shape so that the flame substantially circumvents the device. The device reaches a temperature of 150-350°C in an ordinary household furnace and this means that the dead period of the furnace is substantially doubled on account of the thermal energy accumulated in the device. At the same time, the flame is direct¬ ed closer to the boiler wall and can therefore in an improved an more efficient manner emit its heat to the boiler. For a number of reasons the device preferably has a round shape. First, many boilers are provided with rather small doors so that it is difficult to place eg. a cylindrical device in the combustion chamber. Secondly, a ball has the greatest mass in relation to surface compared with other shapes so that more even heat emission from the device is obtained ' during the * dead periods. Thirdly, a round shape gives a favour- ' able flow pattern so that the flame can circumvent the device and not flash back towards the burner. The device can have support legs or a base which can suitably be designed so that the device inclines some¬ what rearwardly away from the burner for further im- proving flow conditions. The heat storage device operates most effectively during the weak heating seasons, ie. spring, summer and autumn, when a doubling of the dead period of the furnace can be obtained by using a device accord¬ ing to the invention. During the weak heating seasons ordinary oil or gas furnaces do not normally operate very effeciently because the boiler is in fact over- dimensioned at these times of year. By ' using the device according to the invention, there is obtained a substantial improvement in efficiency since the combustion chamber is not nearly cooled to so low temperatures due to the heat accumulated in the de- . vice. During the heating season proper, ie. in winter, there is also obtained a certain improvement in effeciency but not to the same extent as is experi¬ enced during the weak heating seasons. The device is made of metal, preferably of cast iron, which does not form oxide scale when heated to 150- 350°C. The metals forming oxide scale are not par¬ ticularly applicable since the oxide scale works as an insulating layer on the device. * Other metals not forming oxide scale and which can stand the tempera- tures of an oil or gas flame in a boiler can also be used .

Claims: PATENT CLAIMS 1. Heat storage device for oil or gas furnaces, c h a r a c t e r i z e d i n * that the device (4) • is a solid metal block placed in the combustion cham¬ ber of the furnace so that it is touched by the fur¬ nace flame. 2. Heat storage device according to claim 1, c h a r a c t e r i z e d in that the device (4) is made of cast iron. 3. Heat storage device according to claims 1-2, c h a r a c t e r i z e d i n that the device (4) has the shape of a body of revolution, preferably of a ball or a compressed ball. 4. Heat storage device according to claims 1-3, c h a r a c t e r i z e d i n that the device (4) is provided with a support base (5) formed. integral¬ ly with the device and made of the same material. 5. Heat storage device according to claims 1-3, c h a r a c t e r i z e d i n that the device (4) is provided with support legs welded thereon. 6. Heat storage device according to claims 1-5, c h a r a c t e r i z e d i n that the device (4) is provided with a lifting device (1,2) fixed on the up-turned part of the device. I 7. Heat storage ' device according to claims 4 or 5, c h a r*a c t e r i z e d i n that the ' support base or leg. (3,5) is so designed that the device stands at a slightly inclining position in the combustion chamber. OMPI_

Inventors: HANSEN EJNAR INGOLF, HANSEN, EJNAR, INGOLF
Applicants: HANSEN EJNAR INGOLF, HANSEN, EJNAR, INGOLF
Application year: 1983
Main classification: F24H7
IPC codes: F23M13, F24H9