Glass Tank/Glass Furnace Installation
Figure 7 shows a diagram of a typical installation of a SuperOXTM Sensor into a glass tank/glass furnace.
Safety Guidelines
WARNING: You must follow operational safety guidelines when drilling and installing a sensor in an operating glass furnace. It may be possible to use existing furnace openings. When repairing a furnace, or planning for new construction, you should consider drilling the holes for oxygen sensors.
The SuperOXTM Sensor contains a significant number of ceramic parts. It is therefore subject to thermal shock. The sensor must be installed in an area that provides an adequate, turbulent, and consistent gas stream representative of the atmosphere in the process. The sensor must be located so that the “hot” end can measure the oxygen level of the flue gas, at a temperature greater than 1200°F (650°C), but less than 3000°F (1650°C) in a slightly positive pressure situation to prevent air in-leakage.
The sensor cannot be exposed in an area with excessive turbulence or high gas velocity, especially when there is particulate in the atmosphere. In order to comply with these requirements, SSI recommends that, for glass tanks with regenerative heating, the sensor be installed vertically in the center of the regenerator crown or horizontally on the regenerator “target” wall. Please note that target wall life will be significantly less when compared with a vertical, crown installation.
For glass tanks with recuperative heating, SSI recommends installation in a vertical position in the flue gas collector, behind the branch off, but in front of the gate valve. Please remember the temperature constraints when looking for this location.
You must drill 2 ¾ to 3 inch (19.05 to 76.2 mm) holes through the refractory brick. This will allow easy installation and removal of the SuperOXTM Sensor.
Vertical installation
Sensor should be recessed 1 to 2 inches (25.4 to 50.8 mm) into the refractory away from furnace atmosphere. When installing the probe, it is best to insure this length of insertion. From the hot face, one will recess the sensor until the readings begin to change. Once a change has been observed, lower the sensor approximately ½ inch (12.7 mm) and secure the sensor in place.
Horizontal Installation
SSI recommends that the “hot” end of the sensor extend approximately 3 to 5 ½ inches (76.2 to 139.7 mm) beyond the hot face of the refractory. If there is an excessive amount of batch carry-over, or if the gas stream has a very high velocity, it is recommended that the sensor be recessed. Batch carry-over and high velocity gas will erode the sensor and significantly reduce life.
Sensor Preparation before installation
When using the SSI oxygen mounting assembly, place the sensor at the maximum height possible and lower it toward the furnace 2 to 4 inches (50.8 to 101.6 mm) every five minutes. If you do not have an SSI Mounting Assembly, note that approximately 2 hours before installing the sensor, you should lay the sensor on top of the regenerator (for pre-warming), taking care to protect the sensor head and wiring assembly.
Sensor installation (insertion) rate
WARNING: You must follow operational safety guidelines when drilling, and installing a sensor in an operating glass furnace. It may be possible to use existing furnace openings. When repairing a furnace, or planning for new construction, you should consider drilling the holes for oxygen sensors.
Insertion of the sensor should be no greater than 4 inches (101.6 mm) every 5 minutes.
Installation Hints:
The sensor will need to be supported while being installed. The installation process will take 1 to 4 hours depending upon sensor length and rate of insertion. When the sensor is in its final position, it is recommended that the opening be covered or filled with fiber blanket around the protection tube.
NOTE: The sensor is warranted against workmanship defects, but not against damage caused by installing the sensor incorrectly.
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SuperOxTM - Maintenance
It is important to check the sensor’s position every one to two months. If the fiber placed around the protection tube and the bored hole has shrunk, add fiber into the area between the protection tube and the bored hole. Use wooden sticks or dowels. Touching the HOT ceramic tube with a metal screw driver is NOT recommended.
The sensor head should be observed for any excessive temperature. The internal workings of the sensor head will ideally be exposed to temperatures no greater than 150 to 200°F (65 to 93°C).
During troubleshooting, it may be necessary to read the sensor millivolts from the sensor. If you are asked to supply this information, please remove the electrical connection from the head of the sensor and, using a digital voltmeter, measure the sensor millivolts by touching pins “1” and “2,” and then observing the number reading. The number should be between 30 and 125 millivolts during a firing cycle. Check the reading against a millivolt vs temperature Oxygen Chart. You can check the temperature by measuring the millivolts across pins “3” and “4”. These values can be correlated using a “B-Type” thermocouple chart.
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Reference Air System - Installation
The reference air system should be installed in an area protected from excessive heat and dust. It is recommended that it be installed on a column or wall, at a height easily accessible for maintenance of the air pump. The system should be installed with respect to local electrical regulations. The reference airline needs to be run from the reference air system to the head of the sensor. The line can be run using ¼ inch (6.35 mm) tubing (stainless or copper). Terminate the tubing approximately 6 inches (152.4 mm) from the sensor head and finish the connection with flexible tubing included in the sensor carton.
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Reference Air System - Maintenance
The reference air system requires little maintenance. Changing the filter (dependent on the dust level) 4 - 6 times per year ensures that the sensor receives a quality source of reference air for proper function. The amount of reference air supplied to the sensor should be maintained at 0.5 – 1.5 SCFH. The reference air pump needs to be checked periodically to ensure proper operation.