Rockwell Automation T6050 SurgeGard Incipient Surge-Conditioning Module - Manual (Page 36)

ICS Triplex Turbo Machinery Control
8
Application Considerations
Control of turbomachinery presents numerous challenges and opportunities because the surrounding process or
pipeline largely depends on the control systems availability, reliability and efficiency. Among the challenges are:
effective surge control, automation of start-up, adaptable capacity control, optimum load sharing, turbine
overspeed protection and operating close to the process limit to meet increasing production requirements and
efficiency. Most compressor control systems currently on the market are not up to task. They rely on
conventional calculated anti-surge techniques with limited fallback capabilities and inadequate control actions.
Hence, there is risk on tripping a compressor due to surge or field instrument malfunction. Therefore very often
these systems are configured with conservative safety margins that reduce the operating envelope of a
compressor. This leads to lower yield, overall production decrease, loss of revenue and loss of operating profits.
The T6050 SurgeGard™ with its capability to detect incipient surge (a pre-cursor to actual surge) offers a
reliable solution to increase energy savings, identify and correct for shifts in surge points/line and to prevent
compressor trips. This is achieved by the implementation of patented fluidic oscillation measurement which
determines the actual surge points, therefore allowing closer operation to surge limits, providing a wider
compressor operating window and compensating for certain field transmitter malfunctions (offering fallback
features). The following is an application overview of the T6050 SurgeGard™:
Multi-Stage (body) Machines or Machines with Multiple Discharge
Ports
It is necessary to use a differential pressure flow transmitter for each stage or port. Since the differential pressure
signal sensitivity to the velocity pressure changes is critical for detection of fluidic backflow oscillations, it is
important that the flow transmitter does not have a lag of greater than 100 milliseconds. For some applications a
high speed transmitter with a very small sampling delay (ideally less than 7 milliseconds, Statham PD3000 or
equal transmitter) is necessary.
AI Activation Delay
The analog input (AI) from the SurgeGard (4-20 mA output of SurgeGard) is ignored/bypassed (for several
minutes in applications for compressors with large volumes) in the anti-surge compressor controller configuration
until the machine is “on-line” and starting to build a discharge head (already pre-configured in the T6100, T6200
and T6300).
Flow Transmitter Mounting
If a flow transmitter is used as the incipient surge signal, the transmitter should be mounted directly above the
flow element with no connecting tubing where liquid can condense and accumulate. Since many problems have
been encountered on start-up, incipient surge protection and surge control, ICS TRIPLEX recommends this
simple approach. Alternative installation methods can be used successfully, but a careful review of adherence to
clean and short impulse lines is required.