DE2525911A1 - BURNER - Google Patents

Description

BY KREISLER SChDNWALu MbYER EISHOLD FUES FROM KREISLER KELLER SELTING

PATENT LAWYERS Dr.-Ing. by Kreisler + 1973

Dr.-Ing. K. Schönwald, Cologne Dr.-Ing. Th. Meyer, Cologne Dr.-Ing. K. W. Eishold, Bad Soden Dr.J.F. Fues, Cologne Dipl.-Chem. Alek von Kreisler, Cologne Dipl.-Chem. Carola Keller, Cologne Dipl.-Ing. G. Selting, Cologne

Ke / Ax

5 Cologne ι ¹⁰ June 1975

DEICHMANNHAUS AT THE MAIN RAILWAY STATION

The British Petroleum Company Limited, Britannic House, Moor Lane, London ', EC2Y 9BU (England)

burner

The invention relates to burners, in particular burners for burning very lean heating gas-air mixtures.

Today's emphasis on the need for energy conservation and the application of preventive measures pollution caused incineration technology to look for ways and means, low-value ones Fuels and fuel-air mixtures under normal operating conditions are normally not even flammable to burn. As specific examples are the quarry gases from mines, the weather air from mines, the exhaust gases from the most varied of large-scale plants Process and the lean methane-air mixtures to name certain fermentation residues. Aside from wasting energy, there can be unwanted contaminants enter the atmosphere when these gases escape unburned. Those from such sources recoverable energy is not insignificant, and 'theoretical Calculations show that the methane content of the weather air from mines is sufficient to

509881/0810

TtWofl: (0221) 234541-4 Ttl.x : 888 2307 dopa d T.legramm: Dompatent Cologne

to meet the needs of mining machinery in the UK

The invention has the object of including means for burning very lean fuel gas-air mixtures certain mixtures that are normally not flammable to make available. Mixing more regulated Combustion systems tend to be ineffective and lead to pollution. Also for premixed Reaction participants dealt with the combustion theory ■ with the flame properties, e.g. with the temperature in the reaction zone and thus - with the combustion speed and flammability, etc. for the ur- j initial fuel-air mixture alone.

By "borrowing" part of the enthalpy of combustion ' without diluting reactants with products | it is possible to burn very lean fuel gas mixtures. Here one uses "borrowed" heat to the tem-; temperature in the reaction zone above normal final

Flame temperature corresponding to the respective fuel / air ratio of the mixture corresponds to increase.

The invention relates to a burner with a central combustion chamber which has an inlet for the Mixture of fuel and oxidizing agent and an outlet for the combustion gas and having partitions is surrounded, which form helically wound inlet and outlet channels through which the mixture from Fuel and oxidizing agent or the combustion gas flow spirally in countercurrent to one another, the Partition walls isolate the inlet and outlet channels, but prevent the heat exchange between the mixture Allow fuel and oxygen-containing gas and the combustion gas.

In a preferred embodiment of the invention has the burner has the shape of a flat cylinder, the

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Combustion chamber lies in the middle of the cylinder, from which the inlet and outlet channels run in opposite directions to the edge of the cylinder or the disk. This embodiment of the invention is suitable for | Convert withdrawal of heat or the conversion of heat with very 'high efficiency by means of devices which \ thermal energy into mechanical energy or thermal energy into electrical energy, eg, j S.tirlingmotoren arranged in contact with the flat walls of the combustion chamber i are.

Furthermore, a high temperature fluidized bed combustion unit, e.g. contained in a thorium oxide crucible is to be arranged in the center of the oppositely spiraling channels, whereby the dissipation of the heat out of the system at the maximum temperature possible either by radiation or by a heat pipe. The possibility of setting the temperature of the bed regardless of the fuel / air ratio and the flow rate Changing the gas by changing the circulated heat allows the best conditions to maintain in the fluidized bed combustion unit.

In a further embodiment of the invention, the cylinder, which is the oppositely spiraled inlet and contains outlet channels, formed as a toroid. The toroid is an ideal, completely closed one Heating system which, apart from the product gases, does not show any heat loss. This embodiment of the Invention is particularly suitable for the disposal and recovery of very lean, normally unusable Heating gases or for direct heating of air, for example j wise for central heating systems.

The cross-sectional area of the central combustion chamber has a size that is preferably several times that of

9 8 8 1 -1 - Θ-

2515911

Cross-sectional area of the inlet and outlet channels

is, wherein a size of at least three times;

i is particularly preferred. Further, the ratio i of the total surface area of the inlet and outlet channels is', the cross-sectional area of the channels preferably 100 to 1000th

The preliminary ignition of the burner can be done with the help of a! Spark can be achieved, which on a pilot jet of the Fuel or acts on a mixture initially enriched with fuel.

The preferred flow rates of the mixture of fuel gas and air and the length of the spiral are of the fuel / air ratio depends on the mixture to be burned.

In general, the spiral radius for the entire spiral length is in the range from 1:10 to 1:40.

The burner can be made from a flat material. For example, a sheet with certain .tem Distance between the turns spirally wound. The central space of the spiral forms the combustion chamber. The open faces of the sheets are

sealed with a heat-resistant material, preferably heat '■ insulating material, spirally overall j overcome inlet and outlet channels are formed. !

Ceramic materials are also suitable for this form of construction and would be suitable at much higher temperatures.

The burner is particularly suitable for normally gas | shaped fuels, e.g. methane and others normally Gaseous saturated or "unsaturated" hydrocarbons. Liquid fuels can also be burned by either spraying them or

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Bubbling air through the liquid or passing air over the liquid.

The invention also includes a method of burning lean mixtures of fuels and gaseous ones Oxygen carriers, especially mixtures that are under their normal flammability limit. The method is characterized in that the mixture feeds along a spiral inlet channel of a central combustion chamber and the thereby formed Combustion gases from the combustion chamber along an outlet duct, -the counter-spiral runs and is in a heat exchange relationship to the inlet channel.

The invention is described below with reference to the figures.

Fig.l shows a horizontal section through the burner and illustrates the spiral paths of the reactant and product streams.

Fig. 2 illustrates the stability characteristics of two burners in the steady state.

The test burners were constructed from strips of a heat-resistant metal alloy "Inconel 600". Even other.alloys, e.g. the alloy "Nimonic 75", proved suitable.

Burner A Burner B material Inconel 600 tape Tape off Inconel 600 broad 5 cm 5 cm length 229 cm 145 cm Radius of the spiral 9 cm 5 ■ cm

Number of turns of the

Spiral 8 4

Dimensions of the flow channel 0.4x3.5 cm 0.4x3.5 cm

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The spiral channels 1 and 8 were formed by;

the band 2 from the alloy to heat-resistant spacer; pieces, which were arranged on the flat ends, Ge \ has been developed. The combustion chamber 3 simply consisted of a cavity in the middle of the scroll. After the spiral was formed, its edges were sealed with a heat-resistant cement. Thermocouples, igniters j and other instruments were inserted into the cement before sealing, instead of leading the lines between j turns of the spiral to the outside. Thermocouples at the inlet and outlet of the combustion chamber ^; enable the position of the flame to be monitored and show the extent of preheating and heat build-up

I started the burn. These instruments enabled the

Flame to be stabilized in the combustion chamber.

During the operation of the burner, the reactants 4, i.e. the fuel gas and air, flow along the Channel 1. You get through openings 5 in the middle ren fold 6 of the metal band 2 into the combustion chamber.!

After the reaction in the combustion chamber j5, the Combustion products through the channel 8 counter-spiral to the reactants 4 entering. Through the As a result, the reactants 4 become higher temperature of the product gases 7 through heat exchange in the spiral 1 preheated. It is necessary to ignite the burner with the help of a normal rich mixture of fuel and air. After this start-up, the lean gas is introduced, whereupon the reaction continues by itself.

The flame formed in the combustion chamber is in a certain range of gas flow velocities. ten stable. However, this form of burner has the advantage, among other things, that a flashback caused by too little Gas flow rate is caused, the effective length of the heat exchanger coil is shortened because the Flame is moved away from the center of the spiral.

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This results in an automatic self-stabilizing mechanism against flashback. Fig. 2 shows two limit stability curves (gas flow rate depending on the fuel / air ratio), the

.5 illustrate the effect of changing the length of the tape. It has been found that there are almost no limits to flammability provided that the heat of combustion is returned in this way without dilution by product circulation. Self with the small burners described are wide ranges of stable combustion for mixtures with a fuel content achievable of about 30 to 40% of the normal flammability limit. Less than 18% achieved better thermal insulation. enough. Examination of Figure 2 shows that the normal flammability limit of methane is 5.3%.

509881/0810

Claims (9)

Claims Burner, characterized by a central combustion chamber (3) with an inlet for the Mixture of fuel and oxygen carrier gas and an outlet for the combustion gases and provided is surrounded by partitions, the spirally wound inlet and outlet channels (1,8), through which the mixture (4) of fuel and oxygen carrier gas or the combustion gases (7) gegenspiraligj flow, form and isolate the inlet and outlet channels (1,8), but an indirect heat exchange between the gas mixture of fuel and oxygen carrier and the combustion gases. 2) Burner according to claim 1 in the form of a cylinder, characterized in that the channels (1,8) are spirally shaped extend from the central combustion chamber (3) to the edge of the cylinder. 3) burner according to claim 1 and 2, characterized in that the cylinder of spirally wound entry and exit channels (1,8) wound in the shape of a toroid. 4) Burner according to claim 1 to 3, characterized in that the cross-sectional area of the central combustion chamber (3) is at least three times larger than the cross-sectional area of the inlet and outlet channels (1.8). 5) burner according to claim 1 to 4, characterized in that the ratio of the total surface of the walls the inlet and outlet channels (1.8) to the cross-sectional area of the channels is 100 to 1000. 6) burner according to claim 1 to 5, characterized that the ratio of the radius of the spirally 509881/0810 sore inlet and outlet canals (1.8) to the total length of these canals is 1:10 to 1:40. 7) burner according to claim 1 to 6, characterized in that it consists of spirally wound sheet metal, where the center of the spiral is the combustion chamber (3) and the inlet and outlet channels (1, j 8) have been formed by closing the open ends of the spiral made of sheet metal with a heat-resistant material. 8) burner according to claim 1 to 6, characterized in that the inlet and outlet channels (1,8) Made of ceramic materials. 9) Method of burning lean gas mixtures from Fuel and oxygen carriers, especially mixtures, which are below their normal flammability limit lying, characterized in that the mixture is along a spiral inlet channel to a combustion chamber and longitudinally the combustion gases formed from the combustion chamber of an outlet channel, which runs counter-spiral to the inlet channel and in a heat exchange relationship to this stands. 509881/081 Q