US3367570A

US3367570A - Blower for oil gasification burners

Info

Publication number: US3367570A
Application number: US520270A
Authority: US
Inventors: Reichmann Horst
Original assignee: Joh Vaillant GmbH and Co
Current assignee: Vaillant GmbH
Priority date: 1965-02-06
Filing date: 1966-01-12
Publication date: 1968-02-06
Anticipated expiration: 1985-02-06
Also published as: GB1126941A; DK105487C; NL6517109A; NL140961B; DE1501944B2; DE1501944A1; CH445702A; BE675512A; AT255626B; FR1464525A

Description

Feb. 6, 1968 H. REICHMANN 3,367,570

BLOWER FOR OIL GASIFICATION BURNERS Filed Jan. 12, 1966 i A ll) IN VEN TOR: HM W United States Patent fi l-ice V 6 Claims. (Cl. 236-12) ABSTRACT OF THE mscLosUnE A double blower having two inlets and a single outlet is provided for an oil gasification burner. One of the inlets brings in fresh air and the second inlet brings in exhaust gas from the area of the burner. The air and exhaust gas are fed side by side into a discharge channel leading to the burner. Primarily on the side of the discharge channel occupied by the exhaust gas flow is a bimetallic spring which, at temperatures substantially below the burner operating temperature, protrudes into the discharge channel and throttles primarily the flow of discharge gas therethrough. A second bimetallic spring also is positioned in the discharge channel in the side occupied by the exhaust gas flow. This spring performs no throttling action at burner operating temperatures but at temperatures above the burner operating temperatures the second spring moves into the path of flow of the exhaust gas to throttle the same.

The present invention relates to a blower for oil gasification burners. It has already been proposed not only to feed fresh air to the suction side of the blower, but also a portion of exhaust gas from the area of the burner. By returning the exhaust gas through the blower a hot fresh air-exhaust gas mixture is supplied to the mixing chamber in which a gasification of the injected oil mist takes place, so that oil gasification may take place in a hot cyclonic turbulence of this mixture. When a burner of the type indicated is starting, thus prior to ignition thereof, the mixture portion sucked off from the burner area is heated, in a manner as already proposed, artificially, such as by electric heating. It has shown, however, that by the electric heating of the mixture portion the operating temperature of the mixture required for an unobjectionable operation of the oil gasification burner is not yet attainable so that there will occur diificulties in the ignition.

It is therefore the object of the present invention to eliminate these difiiculties of ignition when an oil gasification burner of the type indicated is starting. According to the invention this object is attained by providing that the outlet channel of the blower has arranged therein a heat-sensitive throttling member, which throttles the outlet channel as long as the operating temperature of the fed mixture is not yet attained and which automatically enlarges the cross-section of the outlet channel as the temperature of the mixture increases. As a matter of fact, it has shown that the difiiculties of ignition with a mixture not yet heated up to operating temperature are caused in that the flow rate of the injected mixture required for operation is too great and that a reduced flow rate effected by temporarily throttling of the blower outlet channel substantially facilitates the ignition of the burner.

The throttling member is suitably formed by a bimetallic spring secured to the wall of the outlet channel, bent in cold state and protruding itno the outlet channel, which straightens when being heated and engages the wall of the outlet channel. However, when the burner is started, a reduction in the flow rate of the mixture is not 3,367,576 Patented Feb. 6, 1968 alone of importance. To obtain a flame properly adhering at the burner mouth, in the stage of starting a relatively greater portion of fresh 'air is required than in continuous operation with hot burner.

It has already been proposed for oil gasification burners of the type indicated to employ a blower from a double impeller one half of which sucks air from one side thereof and an exhaust gas portion from the other side thereof. This blower then feeds both streams in juxtaposed relationship into a common outlet channel. When using such a double blower in further modification of the invention provision may be made that the throttling member is arranged in the outlet channel such that it throttles the exhaust gas portion to a greater extent than it throttles the fresh air portion. Thereby, a relative increase in the fresh air portion during the starting period of the burner is obtained. This may be realized in practice in that the bimetallic spring is designed narrower than the common outlet channel and is arranged therein unilaterally such that the fresh air fed by one blower half flows only partly through the throttle formed by the bimetallic spring.

When using such a double blower which feeds fresh air and exhaust gas portion in separate streams a further advantageous possibility is obtained to improve on the operating conditions of such an oil gasification burner. If the burner is run with reduced performance, that is with reduced fuel and fresh air supply, the operating temperature of the injected fresh air-exhaust gas mixture may become too high due to the now relatively greater exhaust gas portion. To avoid this, a further heat-sensitive throttling member may be arranged in the outlet channel in the range of flow of the exhaust gas portion fed by one blower half, which second throttling member throttles the exhaust gas portion when the operating temperature of the mixture is exceeded with increasing temperature. In this manner a safeguard is not only obtained against too small, but also against too high mixture temperatures. It is expedient to have this throttling member provided also by a bimetallic spring secured to the wall of the outlet channel and engaging, however, the wall at operating temperature, which spring has about half the width of the outlet channel and is unilaterally arranged on the side of the exhaust gas feed and bends into the outlet channel with an increase in temperature.

An embodiment of the present invention is schematically illustrated in FIGS. 1 and 2 and described as follows:

A double blower is driven by a motor 1. Motor 1 is connected to a shaft 2 which carries two impellers 3, 3'. Impeller 3 sucks in fresh air through a channel 4. An adjustable throttle valve 4' is mounted in channel 4. Through a channel 5 the impeller 3 sucks in an exhaust gas portion from the area of a burner not shown, which is heated electrically prior to ignition of the burner during the starting period in a manner not shown. The fresh air and the exhaust gas portion are fed by the impellers 3, 3 as juxtaposed streams into a common outlet channel 6 and from there into a mixing chamber not shown. To the wall of outlet channel 6 there is secured a bimetallic spring 7 which is bent in cold state and abuts a stop 8 with a certain bias. Bimetallic spring 7 defines a throttle gap 9 in the outlet channel 6. Spring 7 is narrower than the outlet channel 6 and arranged unilaterally such that the exhaust gas stream fed by impeller 3 is impeded fully and the fresh air stream fed by impeller 3 is impeded only partly through throttle gap 9. Therefore, by the throttling bimetallic spring 7 not only is the flow rate reduced in outlet channel 6, but also the ratio of exhaust gas and fresh air is changed in the sense of a relative increase in the fresh air portion. When being heated the bimetallie spring 7 straigntens and engages the wall of the outlet channel 6 so that when the operating temperature is reached after ignition of the burner, throttling as at 9 will be discontinued automatically.

The wall of outlet channel 6 has secured thereto a further bimetallic spring 10 which is biased against the channel wall in cold state. This bimetallic spring 10 is dimensioned and biased such that it starts bending only when the operating temperature is being exceeded and withdraws from the channel wall until it abuts a stop 12 and then defines a throttle gap 11. The bimetallic spring 10 is designed so narrow and arranged unilaterally in the outlet channel 6 that it only throttles the exhaust gas stream fed by impeller 3. If the oil gasific'ation burner is started with reduced performance, thus, the fuel supply is reduced and at the same time the fresh air throttle valve 4' is closed further, the operating temperature may be exceeded due to the now relatively great exhaust gas portion. In such case, the bimetallic spring 10 becomes operative and reduces the exhaust gas portion by throttling in gap 11.

The invention claimed is as follows:

-1. In a blower device for an oil gasification burner which blower device is of the type having intake means through which the blower sucks in exhaust gas from the area of the burner and sucks in ambient fresh air and having a blower discharge channel into which a stream of exhaust gas and a stream of fresh air are delivered side by side, the improvement comprising: heat sensitive throttling means connected to said device to reduce the cross sectional area in the discharge channel to reduce the fluid flow therethrough so long as the temperature of the fluid therein is below a desired operating temperature and to automatically increase the cross sectional area as the temperature of the fluid approaches said Operating temperature, said throttling means being constructed and arranged to throttle the exhaust gas flow to a greater extent than it throttles the fresh air flow.

2. In a device as set forth in claim 1 and including a second heat sensitive throttling means connected to said device to reduce the cross sectional area in the discharge channel to reduce the fluid flow therethrough so long as the temperature of the fluid therein is above a desired operating temperature and to automatically increase the cross sectional area as the temperature of the fluid approaches said operating temperature, said throttling means being constructed and arranged to throttle the exhaust gas flow to a greater extent than it throttles the fresh air flow.

3. In a device as set forth in claim 1 wherein said discharge channel includes a wall and said throttling means comprises a bimetallic spring secured to said w'all, said spring being bent in the cold state and protruding into said discharge channel and straightening in the hot state to move toward said wall of said outlet channel.

4. In a device 'as set forth in claim 3 in which the blower device is a double blower and the intake means comprises a first intake for the exhaust gas and a second separate intake for the fresh air with the blower feeding the exhaust gas stream and the fresh air stream in juxtaposed relationship into the common discharge channel and wherein said bimetallic spring is positioned so that a major part thereof is in the side of the discharge channel occupied by said exhaust gas stream.

5. In a device as set forth in claim 4 and including a second heat sensitive throttling means connected to said device to reduce the cross sectional area in the discharge channel to reduce the fluid flow therethrough so long as the temperature of the fluid therein is above a desired operating temperature and to automatically increase the cross sectional area as the temperature of the fluid approaches said operating temperature, said throttling means being constructed and arranged to throttle the exhaust gas flow to a greater extent than it throttles the fresh 'air flow.

6. In a device as set forth in claim 5 wherein said second heat sensitive throttling means comprises a second bimetallic spring secured to the wall of the outlet channel and lying flat against said wall at operating temperature and bent in the hot state above said operating temperature to protrude into said outlet channel, said second spring having about half the width of said discharge channel and being positioned on the side thereof occupied by said exhaust gas stream.

References Cited UNITED STATES PATENTS Re. 24,421 1/1958 Patrick 230-114 1,929,776 10/1933 Faber 230129 2,292,082 8/1942 Miller 236-10 2,788,171 4/1957 Kulow 230-419 2,789,808 4/1957 Blackman 103-97 3,038,698 6/1962 Troyer 10397 FOREIGN PATENTS 462,488 7/ 1928 Germany.

HENRY F. RADUAZO, Primary Examiner.