Gas Compression / Vapor Recovery

Problems

• Remote, stand-alone, vapor recovery compressors would occasionally shut down without notice, upsetting tank vapor pressures and creating a small potential for atmospheric release.
• Capillary-style temperature switches were hard to adjust and maintain properly. The actual temperature shutdown setpoints would drift over time.
• Two large gas compressors needed to run all the time to draw down the field gas pressure.
• The PLCs controlling the main gas compressors could only be modified while off-line, necessitating a compressor shutdown for any setpoint change.
• Two dozen safety switches needed to be tested and adjusted quarterly, reducing compressor uptime.

Solutions

• Installed (6) PLCs: four new PLCs and two upgrades.
• Installed (6) HMIs: four new HMIs and two upgrades.
• Installed backup vapor recovery compressors at (3) tank farms.
• Automated those compressors so they would operate in a lead/lag fashion and notify operators of any abnormal conditions.
• Installed RTDs on the compressors' discharge and collected that data into the PLC for alarming, trending and shutdown.
• Installed a portable, VSD-driven gas compressor which could be used throughout the field, as needed, to reduce demand on the main compressors, allowing one to be shut down and used as a backup.
• Networked the field compressors to the existing alarm notification system so operators would know the condition of their compressors at all times.
• Replaced many switches with transmitters, reducing the time required for testing/calibration and increasing compressor uptime.
• Provided detailed electrical drawings including:
  • PLC drawings
  • Motor control drawings

Results

• Increased product quality.
• More productive employees.
• More reliable equipment.
• Better able to document environmental compliance.

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Details

Client: Pacific Coast Energy Company (PCEC)
Location: Orcutt, CA

PLCs:

• (2) Allen Bradley - CompactLogix L35E
• (3) Allen Bradley - MicroLogix 1400
• (1) Allen Bradley - MicroLogix 1200
• 179 discrete, 29 analog

HMIs:

• (5) Allen Bradley - PanelView Plus 6, 10" color touchscreen panels
• (1) Allen Bradley - PanelView Component, 6" color touchscreen panel
• 250 tagnames

Remote Alarming:

• Specter Instruments - Win-911 Enterprise (existing)

Data Historian:

• Microsoft SQL Server (existing)

Other Components Integrated through SCADA:

• Allen Bradley - PowerFlex 70 variable speed drive
• Honeywell - TruLine chart recorders - DR4500

Networking, Protocols, and Drivers:

• TCP/IP
• RSLinx Enterprise
• DH+
• EIA-568A
• RS-232