The AMETEK Model 888 Tail Gas Analyzer was designed with safety in mind. The analyzer requires very little regular maintenance and can be easily isolated from the process. The predictive diagnostics provide information that allows scheduling of maintenance for plant shut down periods.
Double Block Valve
An optional double block flange can be coupled with the Model 888 to provide complete isolation of the analyzer from the process gas. The probe is held securely in place, no safety cable required, no chance of “spontaneous ejection.”
The Model 888 is a IP65/NEMA 4X rated top-of-the-pipe analyzer and can be installed outdoors with an ambient operating range of -20oC to +60oC. All connections and internal components can be accessed from the front of the instrument.
The use of three intelligent diagnostic models identify, communicate, and react to situations that would otherwise lead to unscheduled downtime and transmit this information via a built in Ethernet or Modbus digital connection. The Model 888 local AMEVision user interface gives a technician a level of control while monitoring and/or performing maintenance near the analyzer. The AMEVision interface allows an analyzer to be used as a standalone device. An extension of the local user interface is the ability to connect remotely for communication. The Model 888 can communicate over an Ethernet connection using a standard web browser. All of the major web browsers are supported and no additional software must be installed on the external PC.
Temperature sensors are used to monitor the sample conditioning system of the Model 888 tail gas analyzer. These temperatures are evaluated against two deviation limits. The warning deviation limit, indicates the expected tolerance for temperature control during normal operating conditions. The alarm deviation limit, indicates the maximum allowable deviation before action must be taken to protect the system. If the temperature of the sample conditioning system decreases below the warning threshold, a warning is communicated and the technician would be alerted to a potential problem. If the temperature of the sample conditioning system decreases below the alarm threshold, an alarm is communicated alerting the technician that the analyzer needs immediate attention.
If the warning is the result of a true failure, the escalation from warning to alarm may happen much faster than the technician’s ability to respond to the initial warning. The Model 888 reacts intelligently to the alarm condition to protect itself from damage. The danger posed by the alarm condition is from the condensation or solidification of elemental sulfur vapor somewhere in the sample condition system leading to a plug. In reaction to the alarm, the Model 888 analyzer purges the sample conditioning system of process gas. This automatic reaction to the identified alarm suspends normal operation but protects the sample conditioning system from additional damage thereby reducing the amount of unscheduled maintenance that will be required by the technician.
Monitoring Light Intensity Predicts Cell Maintenance
The Model 888 photometer integrates the signal intensity from multiple individual flashes of the Xenon lamp during each measurement. Every 90 minutes the zero reference gas is measured and the diagnostic routine evaluates the change in signal intensity since the last zero reference gas run. The light intensity reaching the detector is automatically increased by integrating the signal from additional flashes per measurement.
If the signal intensity decreases by a higher than normal amount this unexpected loss of signal is communicated to the technician as a warning that the cell windows may have been fouled and should be cleaned. The analyzer implements the needed correction to the signal integration and the Model 888 returns to normal operation. The technician has been alerted to the problem but understands that intervention can wait until the next scheduled preventative maintenance period to pull the cell and clean the windows. The analyzer will generate an alarm if there is insufficient signal to make accurate measurements when using the maximum integration time limit.