Using a simultaneous "implicit" forward-space, forward-time solution of the basic equations of fluid transportation, the PLMS real-time transient model generates and tracks the hydraulic parameters along the pipeline length. The modelled parameters include Pressure, Flow, Temperature, Density, Viscosity, etc.
Basic Equations :
Ground Heat Flow Model
Through the use of operator-specified inputs like pipeline depth, soil quality, pipeline material, etc. the ground heat flow model generates a temperature profile of around the pipeline at different modelling locations along the pipeline. This model thus enables to accurately calculate the heat loss/gain of the product in the pipeline to the surroundings.
For multi-product pipelines, where different product batches are queued one after the other, the PLMS batch tracking application can track the location and size of each batch, based on the outputs from the transient model. Using this information, the batch tracking application can predict the expected time of arrival (ETA) of a batch at any given location along the pipeline.
Similarly, scrapers launched into the pipeline can be tracked, and their ETAs calculated.
Mass Balance Leak Detection
The model calculated temperature and pressure compensated volumetric ingress and egress of products into/from the pipeline is compared against the instrumentation readings at entry and exit points along a section of the pipeline. These differences in modelled and measured parameters are statistically compared over a period of time, and abnormal errors (after suitable compensation for modelling errors) are used to generate mass/volume balance leak alarm. The size of the leak is also determined from these errors.
Pressure/Flow Leak Detection & Location
Using intermediate instrumentation installed along the pipeline, the modelled pressure/flow parameters at these metered locations are compared with the measured pressure/flow readings. After taking into consideration the instrumentation and modelling errors, the accumulated differences are analyzed and a leak location algorithm determines the location of the leak.