Patent Application
20160033202
The present invention relates to inspection of process furnace interiors and, more particularly, to a door assembly for use in such inspection.
Process heaters are a critical component in the refining and chemical industries. Traditional means of monitoring these high temperature vessels, often rely on highly subjective analysis and/or frequently inaccurate thermocouple data. An imaging radiometer specifically designed for heater inspections can be used to provide valuable performance information from operating heaters. In the hands of a knowledgeable thermographer, accurate data can be obtained and utilized to significantly increase heater throughput while helping to ensure safe operation of the heater.
Most problems in heaters used in the refining and chemical process industries are associated with upsets in day-to-day operations. These upsets range from burner malfunctions to loss of feed stock through the furnace. It is common to use infrared thermography after an upset in order to establish that the furnace is continuing to operate normally.
Another common problem associated with furnaces is refractory break down which is the loss of the insulating layer directly inside the exterior metal of the furnace. This metal will suffer degradation if exposed directly to the temperatures present in the furnace.
In many furnace designs, flame patterns tend to obstruct naked eye viewing of the tubes, precluding visual inspection of the tubes. Accordingly properly equipped thermal imagers may be utilized to obtain imaging of the interior of the furnace, even through visually opaque flame. The internal temperatures of the furnace can be very high e.g., 3000° F. and greater, which is deleterious to the steel tubes in the furnace. Another problem experienced by the furnace tubes is exposure to excessive temperatures caused by burner misalignment resulting in direct impingement on furnace tubes which can cause overheating.
Tube movement is another condition which is experienced in heaters. Most furnaces are built with the notion of tube shifting over time. However if there is excessive movement of the tubes severe problems can result. Thermal imaging has been shown to be a successful way to watch for and monitor tube movement. However, to be effective this thermal energy must be taken from the same place and compared, over time, to allow for accurate indication of tube movement or other problems.
For non-contact measurement of temperature in the furnace it is known to use a hand held emissivity correcting infrared (IR) thermometer which uses pulsed laser technology to precisely measure the true target temperature.
Additional problems that can be experienced by the furnace tubes are leaks which vent the process fluid to the interior of the furnace. While small leaks may cause no immediate harm. If the leak continues and pressure loss continues to increase, catastrophic failures can occur.
Furnaces of the type under consideration have a limited sight area allowed by the peep doors. Still, opening the peep door allows a massive amount of radiant energy to escape the furnace. This can pose a serious safety problem to a thermographer with a hand held thermal imaging device attempting to measure the temperature or inspect the interior of the furnace. Furthermore, it is difficult using a hand held device to ensure that the point of interest in the furnace can be repeatedly inspected at the same location so the condition e.g., temperatures, at that point can be accurately determined.
In one aspect the present invention provides a door assembly having a mounting for positioning a thermal imaging device such that the interior of the furnace can be accurately inspected.
In still another aspect, the present invention relates to a door assembly for use with a process furnace which provides a mounting for a probe assembly to evaluate internal conditions in the furnace.
In another aspect the present invention is related to a peep door assembly which can include either or both of a sight glass or a mounting for a suitable probe assembly e.g., a thermal imaging device.
In yet a further aspect, the present invention relates to a door assembly for use with a process furnace wherein probe assembly e.g., a thermal imaging device, can be articulated to view desired locations on the interior of the furnace.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
As used herein, the word “probe” or “probe assembly” is intended to mean any type of sensor or other device that can respond, detect or monitor a physical stimulus as for example heat, light, sound, pressure, motion, compositional condition or the like and which, ideally, but not necessarily, can transmit a resulting impulse, signal or the like as for measurement, operating a control, recording, or the like. The term “compositional condition” refers to the make-up of the environment or amount of components, to which the probe assembly is exposed. As used herein, the term “thermal imaging device” or variants thereof includes a device which can make non contact measurements of the internal temperate of a furnace or other heated enclosure as well as a thermal imaging camera or other types of IR imaging radiometers.
Referring first then to
Mounted on the metal door face 10A is a peep hole assembly shown generally as 30. As seen more clearly in
In the embodiment shown in
Turning now to
Probe assembly mount 40, as shown, comprises a nut 70 which is internally threaded and which is threadedly received on an externally threaded nipple 72 protruding from facing 10A. Nut 70, which substantially forms a housing, acts in combination with nipple 72 to form a receptacle 74 for receipt of a substantially spherical probe assembly holder 76. Holder 76 has a throughbore 78, a portion of which is threaded. Threadedly received into the threaded portion of throughbore 78 is the threaded nose 80 of a probe assembly 42. As noted above, probe assembly 42 can be one of many types of sensing devices including a laser eye for non-contact temperature measurements in the furnace as well as a thermal imaging device which can take an IR image of the internals of the furnace showing tubes, refractory walls, surfaces etc. Since the probe assembly 42 is connected to the spherical probe assembly holder 76, it can be moved in receptacle 74 formed by nut 70 and nipple 72. To accomplish this, nut 70 is loosened allowing holder 76 to move. To this end, nut 70 is connected to a handle 71 which can be used to tighten and loosen nut 70. Relative to nipple 72 to thus form an articulated joint when nut 70 is loosened. This movement allows the probe assembly 42 to be aimed at any point in the furnace over a large 360° circular area. Further this ability of probe assembly 42 to be articulated over this pattern and then, once at a desired spot to be held in that position in the receptacle 74 by tightening nut 70 permits consistent, repetitive and hence accurate determination of a condition e.g., temperature of a spot in the furnace impacted by the laser, beam from a laser eye probe assembly. It can readily be appreciated that this ability to measure internals of the furnace such as internal temperature, image a particular tube or tubes, a desired location on the interior wall of the furnace or the like at a precise, location and in a repetitive manner ensures that the thermographer or other technician using the probe assembly 42 knows that the measurements made are accurate.
Turning now to
As in the case of the embodiments shown in
A probe assembly mount shown generally as 140 and being essentially the same as that described with respect to the embodiment of
In order to open door assembly 100, there is a loop plate 152 attached to door facing 104 which could have a coil handle as shown in the emobodiments of
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.
