US2058089A - Method of burning liquid fuel - Google Patents

Description

OC. 20,1936. B; H LUNDBQRG ET AL l 2,058,089

` METHOD OF BURNING LIQUID FUEL Filed 00T.. 13, 1955 3 Sheets-Sheet 1 mm www.. |m.. 1|

S S IIII mw m Mm Q iur |.-|U.H....W.m|.--u.-..-- i

Oct. 20, 1936. B. H. L UNDEsc'DRG ET A1. 2,058,085

METHOD oF BURNING LIQUID FUEL A Filed uw. 13, 1953 s sheets-sheet `2 Oct. 20, 1936. B. H. LUNDBORG ET A1. -2,058,089

.METHOD BURNING LIQUID` FUEL A Filed Oct. l5, 1953 5 Sheets-Sheet; 5

Patented Get. 20, 1936 f UNITED sTA'lA-Es PATENT OFFICE METHOD F BURNING LIQUID FUEL Application October 13, 1933, Serial No. 693,516 In Sweden November 17, 1931 8 Claims.

When firing with liquidfuel at or in the neighbourhood of atmospheric pressure, thefuel Was hitherto continuously fed into the furnace through suitablenozzles.

The spreading and mixing of the fuel with the necessary air of combustionlwas, as a -rule, Vaccomplished by giving the fuel a certain velocity or a rotar-y motion by means/of a centrifugal. sprayer N or `by useof compressed air,istea1`n or in some 10 other Way,y so asto effect a vgood mixture of the fuel with air before the combustion. i i -In such a continuous fuel supply it has, however, proved diicult to obtain a satisfactory-combus-tion of minor-fuel `quantitiesper time unit. Smaller quantities'than about V5kg-oil per hour could not, with safety, be comb-ustedin a4 reliable and regular manner, -although in minor heating plants, such as central heating systems `for villas p and minor apartment houses, often a-combustion 210 of only 1-2 kg. oil per hour is necessary. The present invention relates to a method of supplying the. fuel, whereby a particularly widerangedcontrol of the supplied quantity of fuel is made possible, and thelinvention'is characterized by the fact that the fuel is-sprayed into the combustion space intermittently or in a pnlsating mannenwthatis in an increasing and decreasing quantity. Besides the advantageof ehicientandtcomplete combustion, the economically L importantadvantage is gained-that the fuel `consumption corresponds with great accuracy to the actual yneed byregulating the supply; for example by changing` the stroke of the pumping piston, when a supply pump is used. I When ,carrying` outthemethod, the fuel is, without the addition of air, supplied to one or several spraying nozzles in such a Way that, when leaving the nozzlefit flowsin an intermittent cur- ,p rent or in a pulsating current with great variationsin quantity. i l 4 To obtainperfect combustion and a fully satisfactory 're without danger of soot Y formation or extinguishingthe lire, itis found-`fthat certain requirements'and data concerning `both the variations in pressure andrquantity of the liquid fuel as Well as the number of suchvariations per time unit must be observed.

By tests `made accordingly it has been proved 5 that the maximumpressure ofthe oil in the burner should notivb'e lessA than V2atm.,,landthat the pressure should vary `between this lowestv maximum pressureand zero or substantially zero, and thatfthe number-of injections should be at least `lea'uslpreferably, 100,-,500 perminutedepending (Cl. 15S-117.5)

on the viscosity of the fuel, inflammability, and velocity of flame propagation. Y

' vIn minor plants working with comparatively light burning, refinedoils,` 4 to 10 atmospheres may be adopted as a suitable maximum pressure 5? with 300-500 sprayings per minute.

According to the invention, however, botha higherfmaximum pressureanda greater number of` injections per minute than the above mentioned may be used. It is, however, of importance 10V to so adapt the number of injected charges per minutelthat the combustion `of any one fuel chargeiis not wholly completed kWhen the next charge is admitted. A

`When. using a pulsating current with great va- 15 riations it should be-observed that the last mentioned `object is .attained in such a way that the injected quantity of fuel decreases by at least 25-30%.and lWhenworkng with very small quantitiesof fuel .may even decrease by 40-50% of the maximum. quantity, of fuel. In certain cases With small. plants Working with avery low fuel consumption per hour, l for example oil-fired minor central heating systems for villas, it has proved .convenient to work with so great varia- 25 tions of the injected fuel quantity as to 80% and even up to The injection of the fuel is conveniently carried out by means of an intermittently acting pump without the interconnection of any device acting as an air vessel; However, the injection may also 30 be carried out in other ways for exampleby meansof a member, such .as a Valve, which is arranged in the spraying nozzle or the fuel supply conduit and adapted to open periodically and 35 to close more or less. Y y

To obtain a perfectcombustion ofthe fueliinjected from .the spraying nozzle as an intermittent or pulsating current, the fuel is suitably mixed with and finely divided ina continuously admitted air current before the fuel reaches the combustion chamber.

To conduct the oil to the spraying nozzle it is suitable to use` apiston pump. It is then of particularly great importance that the connecting conduits between the pump and the nozzle beias non-yielding or unelastic as possiblaand itmust be. observed that .the conduits do not contain, any pocketslwhcrein air and gases mightaccumulate; Itfhas also been proved that even thesmallest 5d of such accumulations acts asan air vessel and prevents the intermittent-.orstrongly pulsating injections from-taking place. ,Y

Other ,characteristics ofi .the invention will be moreclearlyset forth in fconnectionowiththe following description of the form of the invention illustrated by way of example on the accompanying drawings. The drawings disclose a plant provided with pump, burner, air blower, electric motor and oil purifier.

Fig. 1 shows in longitudinal section an elevation of an injecting device according to the invention. Fig. 2 is an end view thereof, partly in section on the line II-II in Fig. 1. Fig. 3 shows a section on a larger scale along the same line through the pump and associated parts. Fig. 4 shows a plan view of Fig. 3, and Fig. 5 shows in elevation a section on line V-V of Fig. 4.

I is a mantle or housing, wherein an electrical motor 2 is mounted. At one end of said housing a fan 3 is arranged, and at the other end a gearing 4, 5 for operating the fuel oil pump 6 is mounted.

The fan 3 consists of a fan wheel 8 mounted on the shaft 'I of the motor 2, whereby an air current is forced through the spiral-shaped fan housing, past the burner nozzle 9 arranged at the end thereof and surrounded by curved guides I for the air so that the latter is given a rotating or whirling motion to be intimately intermingled with the finely divided fuel injected by the nozzle 9. The fuel is admitted through the conduit II connected to the pressure side of the pump 6.

The pump itself consists of a cylinder I2 with a pump piston I3 therein. The piston is subjected to the action of a spring I4, which forces the piston to accomplish its suction stroke, whereas the pressure stroke is elfected by means of a cam or eccentric disc mounted on the shaft I of the gear 5, said cam I8 acting on a lever Il pivotally journalled about the pin I6. Said lever I'I bears against th-e back end of the pump piston I3 between the pin I6 and the point of contact of the cam I8 against the lever I'I. 'I'he pin I6 is mounted on the lower end of a rod I9, which is movably arranged in a sleeve 20 and subjected to the action of a spring 2 I, which tends to maintain the rod I9 and, thus, the lever arm I'I in a raised position. The highest position of the rod I9 is determined by a pin 22 screwed into the upper end of the sleeve 2D, which pin can be adjusted manually or by means of a thermostat or the like. The sleeve 20 is mounted perpendicularly to the pump piston and in such a position in relation to the cam I8 that the lever arm II, when swung to the position farthest away from the shaft I5, is perpendicular to the longitudinal axis of the pump piston.

By this device the pump piston, in all the control positions of the rod I9, is in a fully inserted position, whereby with safety any air present is driven out and a regular suction of the fuel is insured. The fuel is sucked from the oil-purifier 23 through the conduit 24 and is forced into the conduit 44, which is connected to the conduit II leading to the burner nozzle 9, and to the conduit 25, which latter conduit is closed off by means of a bursting washer 26 and on the other side thereof, communicates with the suction conduit 24 by means of a channel 45 or with the open air or directly with the fuel container. By this arrangement the Ybursting of the conduit II is prevented in case the nozzle 9 should be filled up. The bursting washer must be practically nonyielding, if the intermittent feeding of the fuel through the nozzle is to be maintained. The washer is therefore made with a very small diameter, for example 4-5 mm. 2l and 28 are the suction and exhaust valves respectively of the pump. To prevent leakage of fuel oil past the pump piston I3, the pump cylinder I2 is provided with an annular channel 29 about its central portion. This annular channel 29 communicates with the suction conduit 24 through an additional channel 38.

The fuel supply to the oil purifier is effected through a supply conduit 32 provided with a closing cock 3|. The Oil is admitted into the purifier at the top through the conduit 33 and passes thence through the filter 34 to the conduit 24, which forms the suction conduit of the pump. In the upper portion of the oil-purifier covered by a glass hood 36, any air present in the oil is separated off, and this air is removed through the conduit 38 provided with a closing cock 3'I.

For the lubrication of the various bearings the gearing 4, 5 in the illustrated example is used as a gear driven pump, which obtains lubricating oil out of the well 39 and forces this through an axial boring 40 in the shaft 1, the bearings of the same and also through the channels 4I and 42 to the shaft I5. 43 is a return conduit from the left bearing of the shaft I to the well 39.

In a pumping plant of the present kind it is to be noted that even apparently insignificant resiliency in the conduit may upset the intended result. This is clearly the case where we consider piston strokes of a length of only 0.2-5 mm. and a piston diameter of 6-10 mm.

The fuel injecting nozzle should be of such a character that the fuel is very finely divided when injected into the furnace. To make the division more or less ne, the nozzle may be controlled for example by means of a displaceable rod screwed thereinto and connected with a sprayer body.

It is not necessary that the air be supplied by means of a fan or compressor as illustrated. The air necessary for the combustion may be admitted into the combustion chamber by a natural draught. The advantages connected with the intermittent or pulsating fuel supply are maintained also in such a supply of the air of combustion.

The method and means according to the invention may, of course, be used in connection with the now common automatic devices for igniting and extinguishing under control of one or several thermostats, which are influenced by the pressure or the temperature in the boiler 0r the temperature in the fire-place etc. At the point of control of the fuel supply, a regulation of the air of combustion should also take place. For this purpose one may in the illustrated arrangement cover the suction opening of the fan by a rotatable valve 46 of a known character. As previously stated the pin 22 may be controlled by a thermostat and when this is the case the same thermostat may control the adjustment of the Valve 46 or an additional thermostat may be used for the latter purpose.

Having now particularly described the nature of our invention and the manner of its operation, what we claim is:

l. The method of combusting liquid fuel in the combustion chamber of a furnace at substantially atmospheric pressure which includes the steps of injecting the fuel into the combustion chamber in a pulsating current, mixing air therewith and igniting said mixture and Varying the quantity of fuel in said current per time unit, the current attaining its maximum from to 500 times, per minute.

2. The method of burning liquid fuel in the combustion chamber of a furnace which cornprises spraying a current of fuel into the chamber at a maximum pressure of 4 to 10 atmospheres, mixing air with said fuel, igniting said mixture and Varying said current from substantially 10% of its maximum to a maximum and vice versa fromv 300 to 500 times per minute.

3. The method as claimed in claim 2, in which the air is supplied in a continuous current which moves with the fuel into the combustion chamber.

4. The method of burning liquid fuel in the combustion chamber of a furnace which comprises injecting the fuel in a current of constantly fluctuating content, mixing air with said fuel and igniting the mixture in the combustion chamber.

5. The method as claimed in claim 4 in which an increasing part of the fuel current reaches the combustion chamxber and mixes with air for combustion while a decreasing part of the fuel current is still burning.

6. The process of burning liquid fuel in the combustion chamber of a furnace which comprises the steps of forcing the fuel as a spray into the chamber, varying the flow of the fuel from a minimum to a maximum a number of times of the order of 100 to 500 per minute, mixing air with said fuel and igniting said fuel in said combustion chamber.

7. The process of burning liquid fuel in a furnace which comprises passing a continuous current of air into the furnace, spraying a current of fuel into said current of air, mixing air with said fuel, igniting said mixture, varying said current of fuel in the range of 1/2 kg. of the liquid fuel per hour, to 5 kg. of said fuel per hour, said Variations taking place at the rate of 100 to 500 per minute.

8. A method of burning liquid fuel in a combustion chamber which comprises iiowing a current of air into the combustion chamber, impregnating said current with a spray of liquid fuel, igniting said mixture, and varying the quantity of fuel sprayed from a maximum to a minimum of from 10 to 75% of said maximum, said Variations being continuous and at the rate of from 100 to 500 per minute.

BROR HENNING LUNDBORG. OLOF' VALFRID TILLBERG.

Images