|
ANALYTICAL PROCESSING - REF. #AP002 | View PDF
THE CHALLENGE
Historically, a chemical plant uses analyzers such as gas chromatographs and mass spectrometers to determine the status of their process at any given time. Some of these analyzers are considered critical to the safe operation of the plant and require a smart Safety Instrumented System (SIS). The sample to be delivered to these analyzers must be reliable and representative of the conditions in the process. Should anything happen to the sample delivery system, the plant could be upset or, worse, require a shutdown. The sample delivery system historically includes a flow meter and a flow switch or transmitter. Either way, the operator is notified when there is a problem. How can these systems be made more reliable and add predictive maintenance alerts?
THE BROOKS SOLUTION
Using a Brooks QUANTIM® mass flow meter (Model QMBM) or sensor (Model QMBS) in the sample line allows the operator and the control system to know the actual flow and density of the sample being delivered to the analyzer. In a typical installation, the operator would set the flows using rotameters, such as Brooks’ Model 1350 glass tube or Model 3750 metal tube instruments. Once the flows are established, an additional Safe Instrumented System (SIS) meter is added to the process. This device records flow, density and/or temperature. The Brooks Instrument Model QMBM is ideal for this application. The two output signals are integrated with the safety control system and alarm at decreasing flow (indication the sample lines are being compromised), low flow (indicating the performance of the analyzer is being compromised), and no flow (indicating a major sample line problem). For safe operation of the plant, all three of these alerts are needed.
 The Brooks QUANTIM QMBM flow meter will transmit a temperature or density signal. The temperature signal represents the operating temperature of the device and can indicate unsafe conditions. The density signal represents the sample itself. Air bubbles, water or other contaminants in the sample line can be detected, as well as minute changes in the sample. All of these conditions are important to the safe operation of the sample system.
The challenge in the chemical plant, when operating an SIS system, is to keep all systems up and running. Should a critical component actually fail, the plant must be shut down. Adding SIS instrumentation to protect the system is money well spent. Downtime costs millions; operating sensible and safe instrumentation costs only thousands. In order to operate an analyzer system safely, instrumentation can be used in some very advanced ways. |
|
|
