Environmental Assessment
Volume C-2
Slurry Pipeline
Project Description
Ambatovy Project
16
January 2006
operating range. Detection is expected within 2 to 10 minutes of occurrence
depending on the size and the location of the leak.
Leak detection involves comparing the flow-rates, pressures and densities along
the pipeline based on current flow regime in the line and position of the pipeline
valves. A leak would be recognized by the departure from established norms for
these parameters.
The leak detection system is based on two methods, mass balance (MB)
monitoring and section characteristic parameter (SCP) monitoring. The more
reliable SCP is defined as Q²/(dh/dL), with Q representing the local flow rate and
(dh/dL) representing the slope of the hydraulic gradient (headloss) in the
monitoring section. The MB method alone would create false alarms when the
pipeline is in transient conditions.
The on-line monitoring of data provides pipeline operating personnel instant
access to information about process flow conditions. This access to information
allows safer operation and better maintenance of the pipeline. If there is an
indication of a leak, the pipeline will be shut down, and an inspection team will
be dispatched.
2.5
PIPELINE OVERPRESSURE PROTECTION
A discharge pressure override will always be engaged during pumping operations
to ensure unsafe operating conditions are addressed quickly. The system will be
controlled by pump speed (target steady pipeline flow) with a density alarm on
high or low density from the storage tank. High and low density limits will be
established during commissioning. Adjustments to the concentrate feed rate
must be made which provide a steady-state concentrator operation, which
minimizes pipeline shutdowns.
The pipeline and equipment will be protected from over-pressurization by several
levels of protection by:
•
implementing proven operating procedures;
•
the use of SCADA system software;
•
the use of electrical interlocks (physical or by control loops); and
•
mechanical pressure relieving devices.
The pressure-relief devices will be located at the discharge of the mainline pump,
upstream of the valve station, and upstream of the terminal valves. The pump
station relief devices direct their flow to the pump station agitated storage tanks.
