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Title: Liquid level detecting devices
Claims: What I claim as my invention and desire to secure by Letters Patent is: 1. A liquid level detecting device adapted for use with a vapour generator comprising a stack tube having a lower liquid inlet, an upper vapour inlet, lower connector means for attaching the lower liquid inlet to the vapour generator at a level below the operating liquid level thereof, upper connector means for attaching the upper vapour inlet to the vapour generator at a level above the operating liquid level thereof, and at least one cooling tube with one end communicating with the stack tube at an upper cooling tube inlet and the other end communicating with the stack tube at a lower cooling tube outlet at a level above the stack tube liquid inlet, each cooling tube changing direction at least twice between its inlet and outlet so as to provide at least a first portion extending down from the upper cooling tube inlet to a region below the lower cooling tube outlet, a third portion extending up from the lower cooling tube outlet to a region adjacent the upper cooling tube inlet, and a second portion interconnecting said first and third portions, the first, second and third portions of the cooling tube being disposed relative to the stack tube so that when the stack tube is in use, the first, second and third portions are disposed so that the lower ends of said first and second portions together afford a generally U-shaped collecting region in which any liquid formed by condensation of vapour in said first and second portions will collect in said collecting region, and at least one sensing device located in sensing relationship to at least one of said first, second and third portions and arranged to sense the change in temperature of said portion and to produce a signal in response to sensing a change of temperature of a predetermined magnitude. 2. A device as claimed in claim 1 in which the first, second and third portions are straight and are arranged parallel to the stack tube. 3. A device as claimed in claim 2 characterized in that the said sensing device comprises an actuating member which is pivoted to the first or third portion of the said cooling tube and the device which is to be actuated is mounted on a carrier member pivoted to the same portion of the said tube, at a spaced apart location, the arrangement being such that the actuating member actuates the device when the temperature of the portion of the cooling tube to which it is pivoted changes. 4. A device as claimed in claim 3 characterized in that the actuating member and the carrier member are each pivoted to the first and third portions of the cooling tube. 5. A device as claimed in claim 3 characterized in that the actuating member and the carrier member are each pivoted to the first portion of the cooling tube and to the stack tube. 6. A device as claimed in claim 1 in which at least two cooling tubes are provided, each cooling tube has independent sensing devices, one tube, the high water level cooling tube, has its lower cooling tube outlet communicating with the stack tube at what will be the high water level in use, and the other tube, the low water level cooling tube, has its lower cooling tube outlet communicating with the stack tube at what will be the low water level in use. 7. A stationary or marine vapour generator having a generator drum in which vapour is generated and a liquid level detecting device as claimed in claim 6 attached to said drum, the stack tube of the said device being arranged substantially vertically, the stack tube vapour inlet communicating with the interior of the generator drum at a level above the high water level of the vapour generator and the stack tube liquid inlet communicating with the interior of the generator drum at a level below the low water level of the vapour generator, the detecting device being positioned relative to the drum so that the lower cooling tube outlet of the low water level cooling tube is at the low water level of the drum and the lower cooling tube outlet of the high water level cooling tube is at the high water level. 8. A device as claimed in claim 1 characterized in that at least two cooling tubes are provided and a valve device is provided for selectively connecting the upper cooling tube inlet of each cooling tube to the vapour inlet of the stack tube whilst shutting off the stack tube from the said vapour inlet and a drain provided with a valve is located below the lower cooling tube outlet. 9. A device as claimed in claim 8 characterized in that valve device comprises a valve manifold having an inner sleeve open at one end to the vapour inlet of the stack tube and having at least one series of ports such that in one position of the sleeve the vapour inlet of the stack tube is brought into communication with the stack tube and all the upper cooling tube inlets whilst in other positions the vapour inlet of the stack tube is brought into communication with only one of the upper cooling tube inlets in each such other position. 10. A device as claimed in claim 9 characterized in that the stack tube has an inclined lower limb affording the lower liquid inlet, a vertical intermediate limb communicating with the said valve device affording the upper vapour inlet and at least two cooling tubes disposed between the lower limb and the said valve device. 11. A device as claimed in claim 1, further characterized by alarm devices controlled by the said sensing devices and further being under the control of a further sensing device which activates the said alarm devices only when the stack tube contains steam. 12. A liquid level detecting device adapted for use with a vapour generator comprising a stack tube having a lower liquid inlet with a connector for attachment to the said vapour generator at a level below the operating liquid level thereof and an upper vapour inlet with a connector for attachment to the vapour generator at a level above the operating liquid level thereof, a high level cooling tube arranged as a loop having one end communicating with the stack tube at an upper high level cooling tube inlet and the other end communicating with the stack tube at a lower high level cooling tube outlet at the level above which the water level of the vapour generator must not pass without an alarm being given, the said cooling tube having a first portion extending parallel to the stack tube to below the cooling tube outlet a second portion extending up therefrom parallel to the stack tube to above the cooling tube outlet and a third portion extending therefrom down parallel to the stack tube to the cooling tube outlet, a pair of levers pivoted to the said first and third portions, sensing means cooperating with said levers to sense movement thereof; and alarm means connected to said sensing means and arranged to give an alarm signal when said sensing means sense movement of the levers, a low level cooling tube arranged as a loop having one end communicating with the stack tube at an upper low level cooling tube inlet and the other end communicating with the stack tube at a lower low level cooling tube outlet at the level below which the water level of the vapour generator must not pass without an alarm being given, the said cooling tube having a first portion extending parallel to the stack tube to below the cooling tube outlet a second portion extending up therefrom parallel to the stack tube to above the cooling tube outlet and a third portion extending therefrom down parallel to the stack tube to the cooling tube outlet, a pair of levers pivoted to the said first and third portions, sensing means cooperating with said levers to sense movement thereof, and alarm means connected to said sensing means and arranged to give an alarm signal when said sensing means sense movement of the levers. 13. A device as claimed in claim 12 in which one end of the levers on the high level loop carry the said sensing means and the levers are pivoted at the other end on the third portion and intermediate the two ends on the first portion of the loop, and one end of the levers on the low level loop carry the said sensing means and the levers are pivoted at the other end on the first portion and intermediate the two ends on the third portion. Other info: Inventors: Benham, Hugh Michael (London, EN) Application Number: 433408 Filing Date: 1974-01-14 Publication_date: 1976-02-03 Assignee: ABTEC Limited (London, EN) Primary Class(es): 73/295 116/109, 340/622 Other Classes: US Patent Ref:
Other Refs:
Primary Examiner: Queisser, Richard C. Assistant Examiner: Roskos, Joseph W. Attorney: Oblon, Fisher, Spivak, McClelland & Maier |
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