US3759657A

US3759657A - Atomization burners

Info

Publication number: US3759657A
Application number: US00156622A
Authority: US
Inventors: H Carlsson
Original assignee: Bahco AB
Current assignee: SNA Europe Industries AB
Priority date: 1971-06-25
Filing date: 1971-06-25
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18

Abstract

A burner of the type having a combustion chamber, a porous, fuel atomizing member, combustion chamber fuel supply means, electric fuel igniting means, and with which the atomizing member has an auxiliary chamber and a main chamber, which are interconnected by a constricted connecting passage. Means are also provided for applying a first part flow of combustion air to the combustion chamber via the passage and means for supplying a second part flow of combustion air to said chamber. The improvement resides in the fact that the constricted connecting passage and the first part flow supply means are constructed relative to the second part flow means so that the first part flow is sufficient to sustain initial combustion in the auxiliary chamber but not sufficient to sustain any form of combustion therein upon continued operation of the burner.

Description

Carlsson Sept. 18, 1973 ATOMIZATION BURNERS Hilding Ake Gerry Carlsson, Enkoping, Sweden [73] Assignee: Alitieliilaget EhcWEtiihtiiTi,

Enkoping, Sweden [22] Filed: a June25, 1971 [21] Appl. No.: 156,622

[75] Inventor:

[52]. US. Cl. 431/170 Primary Examiner-Edward G. Favors AttorneyWatson, Cole, Grindle & Watson [57] ABSTRACT A burner of the type having a combustion chamber, a porous, fuel atomizing member, combustion chamber fuel supply means, electric fuel igniting means, and

' with which the atomizingmember has an auxiliary chamber and a main chamber, which are interconnected by a constricted connecting passage. Means are also provided for applying a first part flow of combustion air to the combustion chamber via the passage and means for supplying a second part flow of combustion air to said chamber. The improvement resides in the fact that the constricted connecting passage and the first part flow supply means are constructedrelative to the second part flow means so that the first part flow is sufficient to sustain initial combustion in the auxiliary chamber but not sufficient to sustain any form of combustion therein upon continued operation of the burner.

' Claims, 1 Drawing Figure PATENTEDSEPI 8|975 3,759,657

INVENTOR HILDING AKE G. CARLSSON WATSON COLE GRINDLE & WATSON ATTORNEYS ATOMIZATION BURNERS The present invention relates to an improvement in atomization burners of the type which are provided with a combustion chamber, an atomizing element which is made of porous, heat resistant material, means for supplying liquid fuel to the burner chamber via the atomizing element, and electric ignition means arranged to heat, vapourize and ignite the fuel to initiate the process of combustion, the atomizing element having an auxiliary chamber and a main chamber which communicate through a constricted connection line and which together therewith form a flow passage extending through the atomizing element, and wherein means are provided for feeding a first part flow of combustion air to the combustion chamber via the passage and further means for supplying a further part flow of combustion air to said combustion chamber.

An atomizing burner of this type is known from U.S. Pat. No. 3,531,229. It has been found with burners of the type described that when the initial starting sequence has been passed, the auxiliary chamber of the atomizing element and the constricted connection quickly become blocked withsoot as a result of incom plete'combustion when during the continued operation of the burner the quantity of air supplied in the part air flow through the auxiliary chamber, the constricted connection and the main chamber is relatively small in relation to the amount of fuel supplied to the auxiliary chamber. One seemingly obvious solution to this problem is to increase the magnitude of the part flow. The part flow would then be too great, however, to enable the starting sequence to take place. Consequently, it is desirable to increase the part flow subsequent to starting the burner, but such would require the provision of complicated and expensive automatic regulating devices.

The object of the-invention is therefore to provide a means whereby the problem can be solved simply and cheaply. This is achieved by means of the present-invention which is mainly characterized-in that the constricted connecting line and the means for supplying the first part flow of combustion air are dimensioned relative to the means for supplying the second part flow of cumbustion air in a manner whereby the first part flow is sufficiently large to sustain combustion in the auxiliary chamber when the burner is started up, but insufficient to sustain any form of combustion in said chamber during continued running of the burner when the atomizing element in its entirety has acquired operation temperature.

The present invention is based on the previously unobserved fact that the combustion air required by the main chamber while the burner isin use can be supplied partically in full by an inflow of air from the combustion chamber created by the effect of the combustion gases. in accordance with the invention, the constricted connection and the means for supplying the part flows of combustion air are constructed so that the part flow of combustion air through the auxiliary chamber which flow initself is sufficient to maintain the combustion during the starting sequence -.during the continued operation of theburner is so smallin relation to the flow of fuel to the axuiliary chamberthat practically no combustion takes place in the auxiliary chamber. In this way, blockage of the constricted connection and the auxiliary chamber by soot during the continued operation of the burner is prevented. I

One embodiment of the invention will now be described in more detail with reference to the accompanying drawing, the single FIGURE of which is an axial part section through a burner forming part of a so called vehicle parking heater.

Arranged within a casing 1 arranged for heat exchange between the gases of combustion and a heating medium is a burner chamber 2 formed by a substantially cylindrical sheet-metal shell 3. One end of the combustion chamber extends in the interior of the casing 1 towards an end wall thereof, in which is arranged a sparking plug 5, while the other end opens out towards the interior of the space formed by the casing 1 to prepare the exit of the combustion gases via this space and a not shown exhaust .pipe. The necessary combustion air is supplied by means of fan means (not shown) via a passage 6 to the interior of the casing 1 within a section which is partitioned from the space accomodating the gases of combustion by means of a wall 7.

The burner is supplied with afirst part flow of air through openings 8 disposed in the wall of a tubular end portion of the burner chamber shell 3, the said end portion being located close to the aforementioned end wall and partially surrounding the sparking plug 5. To enable the magnitude of the first part flow of combustion air to be selectively established, means may be provided for adjusting the through flow area of the openings 8, or alternatively said area may be a fixed area. A considerably larger part flow of combustion air is supplied through openings 9 in the form of inclined gills disposed in a wall which is located in a radial plane and which joins the main portion of the combustion chamber shell with the aforementioned tubular end portion.

The combustion chamber 2 encloses an atomizing element 10 made, for example, of sintered stainless steel.

' The atomizing element is generally cylindrical in shape and is arranged coaxial with the combustion chamber shell 3 and is provided at the end thereof facing the sparking plug 5 with an auxiliary chamber 14 and at its opposite end with a main chamber 15 which opens out towards the combustion chamber 2. Arranged between the: auxiliary chamber and the main chamber is a partition 16 in which the constricted connection between the chambers is arranged in the form of one or more openings 17. The sparking plug 5 has an electrode which projects into the auxiliary chamber to leave a suitable sparking gap between the end of the electrode and the partition 16, which constitutes the other pole of the ignition system. The fuel is suppliedto the atomizing element via a fuel line 18, which opens out in a cavity 19 in the atomizing element to finely divide the fuelthrough the pores of the sintered material.

In accordance with the concept of the invention, the openings h and the constricted connection 17 are so dimensioned in relation to the circuit for the parallel flowing additional part flow through the gill like openings 9 that the part flow through theaxuilizry chamber 14 is not sufi'icient to maintain combustion in the axuiliary chamber during the continued running of the burner. Thus, combustion in the auxiliary chamber only .takes place during the starting up sequence,- during which the same small part flow of air is sufficient in relation to the slight quantities of finely divided fuel supplied to the auxiliary chamber through the still relatively cool walls of the atomizing element to sustain the process of combustion.

As an extra precautionary measure against blockages caused by sooting, the ignition system can be arranged when switching off the heater to cause the sparking plug to operate with decreasing supplies of fuel during a shut down period.

The invention is not restricted to the described and illustrated embodiment, but can be modified within the scope of the following claims.

I claim:

1. An atomizing burner of the type having a combustion chamber, an atomizing element made of porous, heat resistant material arranged in the combustion chamber, means for supplying fuel to the combustion chamber via the atomizing element, and electric ignition means arranged to heat, vapourize and ignite the fuel to initiate the process of combustion, the atomizing element having an auxiliary chamber and a main chamber which communicate through a constricted connecting line and together therewith fonn a flow passage through the atomizing element, and means including first supply openings being provided for feeding a first part flow of combustion air to the combustion chamber via the passage and further means including second supply openings for supplying a second part flow of combustion air to said combustion chamber, the size ratio of the connecting line and said first openings to said second supply openings being a first predetermined value sufficient to sustain combustion in the auxiliary chamber when the burner is started up and during continued running of the burner characterized in that the size ratio of the constricted connecting line and said first openings to said second openings are a second predetermined value less than said first predetermined value to an extent that the first part flow is sufiiciently large to sustain combustion in the axuiliary chamber when the burner is started up, but insufficient to sustain any form of combustion in said auxiliary chamber during continued running of the burner when the atomizing element in its entirety has acquired operation temperature.

2. A burner according to claim 1, characterized in that the means for supplying the first and second part flows of combustion air to the chamber further includes a common feed passage, and said first supply openings for the first part flow located between said passage and said chamber, and said second supply openings for the second part flow located between the same passage and the combustion chamber.

3. A burner according to claim 2, characterized in that the through flow area of the first supply openings is fixed.

4. A burner according to claim 1, characterized in that the ignition means is arranged to be operative during a shut down period of the burner with decreasing supply of fuel thereto.

5. In an atomizing burner of the type having a combustion chamber, an atomizing element made of porous, heat resistant material arranged in the combustion chamber, means for supplying fuel to the combustion chamber via the atomizing element, and electric ignition means arranged to heat, vaporize and ignite the fuel to initiate the process of combustion, the atomizing element having an auxiliary chamber and a main chamber which communicate through a constricted connecting line and together therewith form a flow passage through the atomizing element, and means including first supply openings provided for feeding a first part flow of combustion air to the combustion chamber via the passage, and further means including second supply openings for supplying a second part flow of combustion air to said combustion chamber, the size ratio of the connecting line and said first openings to said second openings being a first predetermined value sufficient to sustain combustion in the auxiliary chamber when the burner is started up and during continued running of the burner, a method of avoiding contamination as by soot buildup within said auxiliary chamber and in said connecting line comprising the step of reducing the size of said first openings so that the size ratio of the connecting line and the reduced first openings to said second openings are a second predetermined value less than said first predetermined value to the extent that the first part flow is sufficiently large to sustain combustion in the auxiliary chamber when the burner is started up, but insufficient to sustain any form of combustion in said auziliary chamber during continued running of the burner when the atomizing element in its entirety has acquired operation temperature.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,759,657 Dated September 18, 1973 I t r( HILDING AKE GERRY CARLSSON It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title page, please insert -Claims priority based on Swedish application No. 8829/70, filed June 25, l970-' Signed and sealed this 9th day of April 19714..

(SEAL) Attest:

EDWARD M.I LEIUIL$I-I,JP.. G. MARSHALL DANN Attesztingg Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 503764 69 US, GOVERNMENT PRINTING OFFICE: I969 0-356-334.

Claims

1. An atomizing burner of the type having a combustion chamber, an atomizing element made of porous, heat resistant material arranged in the combustion chamber, means for supplying fuel to the combustion chamber via the atomizing element, and electric ignition means arranged to heat, vapourize and ignite the fuel to initiate the process of combustion, the atomizing element having an auxiliary chamber and a main chamber which communicate through a constricted connecting line and together therewith form a flow passage through the atomizing element, and means including first supply openings being provided for feeding a first part flow of combustion air to the combustion chamber via the passage and further means including second supply openings for supplying a second part flow of combustion air to said combustion chamber, the size ratio of the connecting line and said first openings to said second supply openings being a first predetermined value sufficient to sustain combustion in the auxiliary chamber when the burner is started up and during continued running of the burner characterized in that the size ratio of the constricted connecting line and said first openings to said second openings are a second predetermined value less than said first predetermined value to an extent that the first part flow is sufficiently large to sustain combustion in the axuiliary chamber when the burner is started up, but insufficient to sustain any form of combustion in said auxiliary chamber during continued running of the burner when the atomizing element in its entirety has acquired operation temperature.