US 3078672 A
Description (OCR text may contain errors)
3,078,672 5 FOR OPERATING A CONTINUOUS S. MEURER PROCESS AND APPARATU OR INTERMITTENT COMBUSTION ENGINE Filed March 22. 1960 Feb. 26, 1963 1 N VE NTOR Jfeyfrzo Mew/"er PROCESS AND APPARATUS FDR OPERATING A CONTEQIUGUS R INTERMITTENT COMBUS- TION ENGINE iegfried Meurer, 'Nnrnberg, Germany, assignor to Maschinenfabrik Augsbnrg-Nurnberg A.G., Nurnberg, Germany Fiied Mar. 22, 1960, Ser. No. 16,825 Claims priority, application Germany Mar. 28, 1959 Claims. (Cl. 60-39.71)
This invention relates to a continuous or intermittently operating internal combustion engine and the method of operating the same.
In the construction of each combustion chamber, the end to be achieved is to obtain a complete combustion of the fuel injected into the chamber while at the same time keeping the physical length of the chamber to a minimum.
The object of this invention is to produce a practical solution for this problem in view of knowledge acquired in the burning of hydrocarbons.
In conventional combustion engines, the combustion air and fuel is brought into an intimate mixture by injecting the fuel through fine atomizing nozzles into the air flow and by means of a naturally produced or specifically created air movement producing a vaporization of the suspended drops of liquid fuel and mixing the resulting fuel vapors with the air. According to this invention, the fuel is treated in a different Way. The fuel is not mixed in fine atomized form with the air, but is vaporized before being mixed with the air. It is found that this is best done by applying the liquid fuel in the form of a thin film on a suitably heated surface. It has been found that the speed at which each liquid particle vaporizes from the surface, or in other Words the dwell time of a droplet of liquid fuel on the heated wall, can be kept to a minimum at a certain temperature.
In an article by Tamura et a1. published in Seventh Symposium International on Combustion, Butterworths Scientific Publications, 1958, London, it is disclosed, for example, that for a hydrocarbon with a formula C H a much shorter dwell time exists for a fuel particle on a wall having a surface temperature of 340 C. than, for example, for a particle on a wall having a surface temperature of 900 C. However, another matter has to be considered in the problem of producing the shortest possible combustion time for the fuel-air mixture. This, namely, is the question of how far the chemical constitution of the fuel has been changed during the mixture forming process, as it is known that the capability of the fuel molecule to combine with oxygen is dependent upon its chemical structure.
If a fuel having a high rate of decomposition is used in a combustion chamber, the time required for preparing the fuel prior to its combustion is not short enough to prevent a chemical decomposition of the fuel from taking place under the influence from heat flame radiation. This leads to the fact that hydrogen atoms have time to free themselves from the fuel molecule and results in that a gradually less reactive molecular structure is left, which again leads to a residual fuel having a long undesirable after-burning time. To avoid such after-burning, it has been customary to supply the combustion chamber with additional air to produce a higher turbulence therein. Such additional air, in many cases, is not desired since it is not used because of its oxygen content but only for producing turbulence in the air mixing process. As the oxygen is not necessary for combustion because sufiicient oxygen was originally present, this additional air only lowers the combustion temperature and thus slows still further the reaction speed of the already slowly reacting fuel molecules.
atent "ice The process of this invention is consequently different from that heretofore used in combustion chambers. The fuel is not injected by a nozzle directly into the combustion air or injected over a short free path so that at least a portion thereof is ignited by an ignition means, such as a flame holder or spark plug. In this invention, the fuel is applied, without atomization, immediately in the form of a thin film on the wall of the combustion chamber. The process is preferably used in cylindrical, hollow body, or tubular shaped combustion chambers wherein the application of the fuel on the inner surface of the chamber can be done continuously or intermittently. It is important that the combustion air movement be co-ordinated with the application of the fuel for a successful forming of a film of fuel. To avoid atomization of the fuel, it is applied with a low velocity on the combustion chamber wall while the actual spreading of the fuel as a film on the surface of the wall is carried out essentially by the air itself. Thus, it is found advantageous to give the air a strong swirling movement in the hollow body shaped combustion chamber. In this way, the fuel is applied in the form of a helical film on the wall surface while at the same time the temperature of the surface is kept at a temperature resulting in the shortest dwell time of the individual fuel particles. The control of the wall temperature is accomplished by passing cooling air over the outer wall face of the combustion chamber which permits maintaining the temperature of the inner wall surface at the desired value. By dividing the intake air flow into combustion air and wall cooling air, the walls are always brought to a temperature corresponding with the type of fuel used. By so doing, it is possible to produce an excellent combustion efiiciency regardless of the type of fuel used. The importance of applying the fuel as a film on the surface of the combustion chamber is emphasized so that nozzles which inject fuel at high speed and atomize the fuel are not required in this invention, except for the sole purpose of starting combustion. Thus, for starting, a special fuel nozzle is employed at the point of ignition. In order to produce a strong air swirl in the combustion chamber for the purpose of spreading the film of fuel on the combustion chamber wall, a series of adjustable guide vanes is used in the air intake duct.
The means by which the objects of the invention are obtained are disclosed more fully with reference to the accompanying drawings, in which:
FIGURE 1 is a longitudinal cross-sectional view through the combustion chamber of this invention;
FIGURE 2 is an enlarged detail cross-sectional view through the fuel injection nozzle of FIGURE 1;
FIGURE 3 is an enlarged cross-sectional view taken on the line 3-3 of FIGURE 1; and
FIGURE 4 is a cross-sectional view of a modification of the structure of FIGURE 3.
In FIGURE 1, the primary combustion chamber v1 is assumed to be located between an air compressor for furnishing intake air and a gas turbine. Chamber 1 is formed as an annular tube in the form of a cone such that the cross-sectional diameter decreases from the air inlet end to the outlet end at an angle preferably of about 7 to the longitudinal axis of the chamber. Compressed air is fed into opening 2. This air passes through the primary combustion chamber within which the fuel is burned. Fuel injection nozzle 3 represents but one of several nozzles which may be used. The fuel emerges through the slit opening 3a and is immediately deposited upon the inner wall of chamber 1 as a solid fuel jet 4 and, Without traversing any free path, is immediately spread as a film of fuel 4a on the inner wall of chamber 1. As shown in FIGURE 2, the slit opening 3a is approximately perpendicular to the direction of the air flow within the chamber.
Mounted in the combustion cham or between nozzle 3 and the outlet end of the chamber is an electrical spark means 5, such as a spark plug, which is energized from an electrical source 5a. A combustion starting aid in the form of an auxiliary nozzle 6 is mounted in front of the spark means 5. The widely scattered fuel jet 6a emitted from nozzle 6 is directed toward spark means 5. This auxiliary nozzle 6 is used only for starting, and once the combustion chamber has been heated suificiently by the combustion gases, the auxiliary nozzle is cut olf. For producing an intensively rotating and directed air flow or air swirl 7 in the combustion chamber, conventional means for producing an air swirl are used, such as the guide vanes 8, adjustable by a hand crank 9, for directing the air flow. Automatic adjustment may be employed. Separated by a distance 10 from combustion chamber 1 is a coaxially mounted outer cylinder 11, thus forming an air passage 12 between the inner and outer tubular members, through which a part of the intake air is passed. Consequently, the air passing through passage 12 permits the inner wall of chamber 1 to be cooled to a temperature at which the fuel has its minimum dwell time on the combustion chamber wall. The quantity of air passed through passage 12 is controlled so that the cooling effect upon chamber 1 can be varied. For accomplishing this, an air control member is mounted in the entrance to passage 12, this member being actuated in response to a thermostat 14 mounted in the'wall of combustion chamber 1. As shown in FIGURES 1 and 3, this control member is composed of a fixed ring 15 having radial slots 15:: and an abutting movable ring 16 having radial slots 16a, ring 16 being rotatable'around the longitudinal axis of chamber 1. Such rotation is achieved by means of a motor 17 responsive to thermostat 14, pinion 1S driven by motor 17 'and' engaging rack 19, which is joined to ring 16 by arm 19a. Rotation of ring 16 will either open or close air passageways through the slots in rings 15 or 16. In the modification shown in FIGURE 4, louvers 13a are used instead of the rings Band 16 of FIGURE 1. The axles of these louvers extend outwardly of cylinder 11 and are joined by means of crank arms to a ring 1612 rotatably mounted on the outer surface of cylinder 11. By moving rings 16b either manually or from motor 17 actuated in response to thermostat 14, the louvers can be opened or closed.
As the combustion proceeds in chamber 1, the temperature of the gases in the chamber increases strongly in the direction of the flow of the gases. ecause of the strong air swirl in the combustion chamber, the specific lighter parts of the gases, that is to say, the gases which by reason of being burned have a higher temperature and less density, flow off toward the central core along the longitudinal axis of the chamber, while the cooler and more dense gases are thrown by centrifugal force toward the wall of the combustion chamber. As combustion further progresses, the total volume of air in the chamber is used for combustion, and therefore additional cooling air must be supplied for cooling the structural parts of the chamber. Rather than supplying this air by radial openings in the wall of the combustion chamber, nozzles 20 mounted on the ends of tubes 21 are directed tangentially of the direction of the air swirl in chamber 1. These nozzles 20 further serve to maintain the air movement required in chamber 1 or even to increase this air movement. The flow of air through tubes 21 is controlled by valves 21a. It is therefor ensuredthat the additional air swirl emitted from nozzles 20 is directed againstthe inside of the combustion chamber wall between the primary air swirl 7 in the chamber and the surface of the wall. When it is necessary to produce an increase in the local air turbulence in the case of very slowly combustible fuels, these cooling air jets are used to increase the air turbulence by directing them partially against the movement of the air swirl 7. However, it is noted that this combustion chamber o'pcrates without any essential additional air supply inasmuch as the temperature in the combustion zone of chamber 1 is kept as high as possible.
The strong and potential air swirl which approaches the formation of a free vortex results in an air pressure differential. Therefore, a relatively low pressure exists in the core along the longitudinal axis of chamber 1. This creates the ranger of forming a too high back pressure in the core at the outlet opening of chamber 1. Advantage is taken of this back flow to produce good combustion under partial load conditions by recycling the burned gases. For example, by means of pipe 22 communicating with the core of the outlet of chamber 1 and the pipe 24 with valve 25 communicating with the inlet end of chamber 1, the core of the air swirl can be used to produce a circulating flow within the combustion chamher in such a manner that burned gases enter through pipe 24 and emerge through pipe 22 and flow along the axis of the combustion chamber. Depending upon existing pressure conditions, this circulating air fiow may be reversed. Under certain conditions, it is desired to introduce tertiary air through pipe 22a into the outlet opening of chamher 1 and into the core of the chamber. The tertiary air inlet 22 is designed with air guide elements 221) which direct the air radially outward along the end of the combustion chamber so as to return to the outlet in a loop as indicated by the arrows 22c in FIG. 1. Again, combustion gases can be supplied through the intake pipe 24 by means of a fuel pipe 24a while fresh air is simultaneously supplied to the core through pipe 220. When the chamber is operating under full load, means can be provided so that the cycle contains mainly fresh air so that there is no recycling of burned gases. During partial and, when the iron being converted contains phosphorus, its contents in lime being uncombined to phosphorus. It is contemplated that phosphate slag of suitable fertilizer gradeis obtainable, in some cases without having to draw out slag until the converting operation is completed. In the case of silicon-bearing iron grades, iron losses are kept low owing to the fact that when a basic reagent is injected, silica will combine therewith more readily than with iron, thus reducing the formation of iron silicate. loads, this recycling circulation is composed of hot exhaust gases so that the combustion chamber temperature is correspondingly kept hot.
The process of fuel mixture forming and combustion is as follows:
The apparatus is started by passing intake combustion air through chamber 1. Simultaneously the main fuel nozzle 3 and auxiliary starting nozzle 6 are opened and spark means 5 energized. The film 4a of fuel emitted from nozzle 3 is spread under the action of air swirl 7 onto the iner wall surface of the combustion chamber. A flame is produced by spark means 5 through the scattered fuel 6a emitted from nozzle 6. As soon as the temperature in the combustion chamber reaches the neces. sary level, the fuel from film 4a evaporates. The vapors so formed are passed by the air swirl 7 to the fuel ignited by spark means 5 and thus ignited. This ignition zone is followed by the actual combustion zone which is kept supplied with fresh fuel by the air swirl maintained in chamber 1. The combustion zone extends roughly from the auxiliary nozzle 6 to the outlet of chamber 1. It should be noted that contrary to conventional systems the secondary air nozzles are arranged in the combustion zone where they help to maintain the air and assist complete combus tion at this point. The now occurring fast increase in temperature in the combustion chamber and theintcnsivc radiation of the flame speeds up the vaporization of the fuel from film 4a, and therefore always increasing quantities of fuel vapors are carried along by the air swirl 7, mixed with the air swirl and taken into the combustion zone. The auxiliary starting nozzle is then shut off.
The fuel air mixture continuously being passed to the combustion zone is controlled in volume by the vaporization of the fuel film a which, in addition, is dependent upon the air volume as controlled by jets 8 and thus is dependent upon the air movement itself. The temperature of the combsution chamber Wall is regulated to the minimum dwell time of the fuel being burned. A corresponding adjustment of the air volume control means 13 in response to the thermostat 14 results in that the combustion chamber wall is accordingly cooled, that is to say, the wall is kept at the given minimum dwell time for the fuel being burned.
Having now described the means by which the objects of the invention are obtained.
1. A method of burning liquid fuel in a combustion chamber comprising directly applying the liquid fuel in unatomized form as a thin film adhering to a large surface area on the inner Wall of said chamber, main tainiug said surface area at a temperature resulting in the minimum dwell time for a fuel particle before vaporization from said film at any working load for said chamber, passing strongly swirling combustion air around the longitudinal axis of said chamber and over said film to mix air with fuel vaporized from said film, and then igniting and burning the air and fuel to form combustion gases.
2. A method as in claim 1, said surface area temperature being maintained by a cooling medium comprising at least in part the combustion air for said chamber.
3. A method as in claim 2, further comprising introducing a stream of additional air tangentially into said air swirl in the direction of the air flow through said chamber.
4. A method as in claim 3, further comprising recycling a portion of the combustion gases produced in said chamber from the outlet to the inlet of said chamber and through the core of the air flow through said chamber, and then through an exhaust pipe.
5. A method as in claim 3, further comprising introducing fresh air into the core of the air flow through the gas outlet side of said chamber.
6. A method as in claim 3, further comprising simultaneously introducing recycled combustion gases into the combustion air inlet side of said chamber while introducing fresh air into the outlet side of said chamber.
7. A method as in claim 6, further comprising proportioning the quantities of recycled combustion gases and fresh air introduced into said chamber so that maximum air is used at full working load, and more recycled gases used at partial loads.
8. A method as in claim 6, further comprising proportioning the quantities of recycled combustion gases and fresh air introduced into said chamber in dependence upon the Wall temperature of said combustion chamber.
9. A method as in claim 1, further comprising introducing additional fuel mixed with air into said air swirl for distribution throughout said chamber.
10. A method as in claim 1, further comprising introducing a stream of additional air into the strongly swirling combustion air in a direction opposite to the air flow through said chamber.
References Cited in the file of this patent UNITED STATES PATENTS 2,482,394 Wyman Sept. 20, 1949 2,599,103 Goddard June 3, 1952 2,621,477 Powter Dec. 16, 1952 2,628,475 Heath Feb. 17, 1953 2,636,345 Zoller Apr. 28, 1953 2,811,833 Broifitt Nov. 5, 1957 2,896,914 Ryan July 28, 1959 FOREIGN PATENTS 654,122 Great Britain June 6, 1951 754,847 Great Britain Aug. 15, 1956 460,206 Italy Nov. 13, 1950 230,332 Switzerland Mar. 16, 1944