Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-11-25
1998-10-13
Mullen, Jr., Thomas J.
Communications: electrical
Condition responsive indicating system
Specific condition
340588, 340506, 356 44, 356301, 374116, 374130, 374131, 374137, 25022718, G08B 1700
Patent
active
058218610
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to monitoring wall temperatures of reactor vessels such as, for example, a high temperature chemical reactor vessel as used in the petrochemical industry.
A high temperature refractory-lined reactor vessel of a type used in the petrochemical industry generally comprises an upright cylindrical side wall and a conical roof, the temperature in the vessel increasing from the bottom up. The wall (side wall and roof) of the reactor vessel is formed by a metal shell having on the inside thereof a refractory lining. Hot spots (localized overheating) can occur, particularly in the conical roof, and these can damage and eventually destroy the refractory lining of the vessel. If not detected early, hot spots can lead to general failure of the reactor vessel. It is therefore desirable that the development of a hot spot be detected as early as possible. In practice, hot spots tend to be small in extent (of the order of 150 mm in diameter) and this makes them difficult to detect.
Previously-considered methods of monitoring the shell temperature of reactor vessels include the use of infra-red scanners, thermocouples, and filamentary sensors of the type that rely on the temperature-dependent resistance of special semiconductor material between a pair of conductors. Infra-red scanners are expensive, and the data they capture is in the form of images which are difficult to store and process electronically. Thermocouples are also expensive, particularly if high resolution is required, as the resolution depends on the number of thermocouples per unit area.
A filamentary sensor of the above-mentioned type, whilst able to detect the development of a hot spot, does not enable one to pin-point readily the distance along its length where the hot spot occurs.
It is desirable to provide a system of monitoring the shell temperature of a reactor vessel in a way that is able to provide an accurate indication of the existence as well as location of a hot spot in the reactor vessel.
According to one aspect of the present invention there is provided a method of monitoring wall temperatures of a reactor vessel, wherein a length of optical fibre is arranged in thermal contact with a wall portion of the vessel, and an optical time domain reflectometry system is employed to monitor the respective temperatures at successive points along the said length of optical fibre.
Where the wall has axial symmetry, and the operating temperature of the vessel increases from one axial end thereof to the other, the optical fibre may advantageously be coiled helically, or spirally, about the axis of symmetry of the wall.
According to a second aspect of the present invention there is provided a reactor vessel installation, comprising a reactor vessel having a wall portion, a length of optical fibre arranged in thermal contact with the said wall portion, and optical time domain reflectometry processing means connected to the optical fibre for monitoring the respective temperatures at successive points along the said length of optical fibre.
Where the wall has axial symmetry, the optical fibre may be coiled helically, or spirally, about the axis of symmetry of the wall.
The installation may further include means operable selectively to change the temperature of the optical fibre locally, in a band which extends axially of the vessel. The said means may be in the form of an axially extending fluid line with lateral openings therein for directing jets of fluid onto the vessel in the said band.
The optical fibre may lead to an extended portion which is out of thermal contact with the wall of the vessel, the extended portion being provided with a heating pad to permit localised heating of the extended portion to a predetermined, accurately known temperature.
The optical fibre may be sheathed in a metal tube which is affixed to or embedded in the wall.
The wall may comprise a metal shell and a refractory lining internally of the shell, the metal tube being affixed to the outside of the shell by means of a heat conductive cement.
The opt
REFERENCES:
patent: 3567895 (1971-03-01), Paz
patent: 4384793 (1983-05-01), O'Brien
patent: 4440509 (1984-04-01), Agarwal
patent: 4703175 (1987-10-01), Salows et al.
patent: 4767219 (1988-08-01), Bibby
patent: 4823166 (1989-04-01), Hartog et al.
patent: 4827487 (1989-05-01), Twerdochlib
patent: 4830513 (1989-05-01), Grege
patent: 5094702 (1992-03-01), Kothmann et al.
patent: 5251274 (1993-10-01), Carlstrom et al.
patent: 5348396 (1994-09-01), O'Rourke et al.
David Dillwyn P.
Hamman Jakob J.
Hartog Arthur H.
Middendorp Marc J.
Lee Benjamin C.
Mossgas (Pty) Limited
Mullen Jr. Thomas J.
York Sensors Limited
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