US4688627A — Detecting leaks in a heat exchanger in operation

Claim 1

Independent Claim 187 words

A process for detecting leaks in a heater exchanger for heat exchange between two substantially gaseous fluids circulating within said heat exchanger, one of said fluids being at a higher pressure and the other at a lower pressure, comprising: temporarily storing a first predetermined amount of tracer gas; carrying out calibration by injecting said first predetermined amount of a tracer gas into the lower pressure fluid before it enters the heat exchanger while the heat exchanger is operating and detecting said tracer gas in said lower pressure fluid leaving said exchanger; and repeating the following steps: (a) temporarily storing a second predetermined amount of tracer gas; (b) injecting said second predetermined amount of the tracer gas into the higher pressure fluid before said higher pressure fluid enters the heat exchanger while the heat exchanger is operating; and (c) detecting the presence of said tracer gas in the lower pressure fluid leaving the exchanger after said injection has been completed, and generating a signal representative of the content of the tracer gas in said lower pressure fluid leaving the exchanger after each injection, said signal being time integrated.

Claim 2

Dependent Claim 187 words

A process for detecting leaks in a heater exchanger for heat exchange between two substantially gaseous fluids circulating within said heat exchanger, one of said fluids being at a higher pressure and the other at a lower pressure, comprising: temporarily storing a first predetermined amount of tracer gas; carrying out calibration by injecting said first predetermined amount of a tracer gas into the lower pressure fluid before it enters the heat exchanger while the heat exchanger is operating and detecting said tracer gas in said lower pressure fluid leaving said exchanger; and repeating the following steps: (a) temporarily storing a second predetermined amount of tracer gas; (b) injecting said second predetermined amount of the tracer gas into the higher pressure fluid before said higher pressure fluid enters the heat exchanger while the heat exchanger is operating; and (c) detecting the presence of said tracer gas in the lower pressure fluid leaving the exchanger after said injection has been completed, and generating a signal representative of the content of the tracer gas in said lower pressure fluid leaving the exchanger after each injection, said signal being time integrated.

Claim 3

Dependent Claim 55 words

A process according to claim 1 for detecting leaks in a heat exchanger for super heating steam constituting said lower pressure fluid, wherein step (b) includes condensing a minor part of the super heated steam flow leaving the heat exchanger, degasing the condensation water and sensing the uncondensable gases resulting from degasing for tracer gas.

Claim 4

Dependent Claim 42 words

A process according to claim 1, wherein said second predetermined amount of tracer gas is stored in a calibrated enclosure and then forced into said heat exchanger during step (b) with pressurized inert driving gas within a period lower than 10 seconds.

Claim 5

Dependent Claim 12 words

A process according to claim 1, wherein the tracer gas is helium.

Claim 6

Independent Claim 206 words

A device for detecting and assessing the size of leaks in a heat exchanger during operation thereof, said heat exchanger having a circuit for a higher pressure gas and a circuit for a lower pressure gas in mutual heat transfer contact, comprising: (a) means for temporary storage of a first predetermined amount of said tracer gas; (b) means for rapidly forcing said first predetermined amount into the lower pressure gas of said heat exchanger at an inlet of the lower pressure gas circuit; (c) means for sampling the lower pressure gas at an outlet of said lower pressure gas circuit following admission of said tracer gas into said lower pressure gas circuit; (d) means for temporarily storing a second predetermined amount of tracer gas, said second predetermined amount being higher than said first predetermined amount; (e) means for rapidly forcing said second predetermined amount into said inlet of said higher pressure gas circuit; (f) means for sampling the higher pressure gas at an outlet of said higher pressure gas circuit following admission of said tracer gas into said higher pressure gas circuit; (g) means for extracting tracer gas which is possibly present from the sample; and (h) means for measuring the quantity of extracted tracer gas.

Claim 7

Independent Claim 206 words

A device for detecting and assessing the size of leaks in a heat exchanger during operation thereof, said heat exchanger having a circuit for a higher pressure gas and a circuit for a lower pressure gas in mutual heat transfer contact, comprising: (a) means for temporary storage of a first predetermined amount of said tracer gas; (b) means for rapidly forcing said first predetermined amount into the lower pressure gas of said heat exchanger at an inlet of the lower pressure gas circuit; (c) means for sampling the lower pressure gas at an outlet of said lower pressure gas circuit following admission of said tracer gas into said lower pressure gas circuit; (d) means for temporarily storing a second predetermined amount of tracer gas, said second predetermined amount being higher than said first predetermined amount; (e) means for rapidly forcing said second predetermined amount into said inlet of said higher pressure gas circuit; (f) means for sampling the higher pressure gas at an outlet of said higher pressure gas circuit following admission of said tracer gas into said higher pressure gas circuit; (g) means for extracting tracer gas which is possibly present from the sample; and (h) means for measuring the quantity of extracted tracer gas.

Claim 8

Dependent Claim 32 words

A device according to claim 5, wherein the measuring means comprise a mass spectrometer and the sampling means comprise means for aspirating a predetermined minor flow rate of said lower pressure fluid.

Claim 9

Dependent Claim 42 words

A device according to claim 5, for detecting leaks in a heat exchanger for super heating steam constituting said lower pressure gas, wherein said aspirating device includes means for condensing steam and aspirating part of the uncondensable gases present in said steam.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-08-24	1991-02-23	1991-08-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-08-24	1995-02-23	1995-08-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-08-24	1999-02-23	1999-08-25	$7700.00	Window Closed / Lapsed

Detecting leaks in a heat exchanger in operation

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