Petrobas Chooses In-Rack Flow Computer Flyer0 pages

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Petrobras Chooses In-Rack

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Flow Computers f^*ni0Nna,ural

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In the heart of this Brazilian rainforest, in the

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Urucu province, 38 flow streams of natural gas

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are transferred to an oil treatment plant owned by

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Petrobras. The Urucu province is the second largest

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natural gas reserve in Brazil with an average daily

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production of over five million cubic meters per

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day. Because of recent regulations published by the

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National Oil Agency requiring a better measurement

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of accuracy for oil volume transfer, Petrobras needed

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to review their existing installations and specify

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equipment compliant with these new regulations.

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"If we had chosen the classic model of dedicated flow

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computers (EMED), the costs and the engineering

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for the presentation of results would be very high,

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since for the implementation of 68 EMEDs we had an

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average cost of U$ 40.000 per unit, where the units

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would vary from 4" to 10" and pressure class varying

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between 300# and 2500# (19 units)," said Francisco

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Carlos Campana Aragon, Senior Equipment Engineer

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for Petrobras.

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ProSoft

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TECHNOLOGY

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Because of this high cost, this was clearly not an

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option for Petrobras. Aragon then discovered ProSoft

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Technology's in-rack flow computers for Allen-Bradley

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PLC and SLC platforms.

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Four 2100-AGA modules were installed in an 8-slot

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Allen-Bradley chassis (PLC 5/80) to calculate the

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volume for the 38 flow streams transferred through

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the oil treatment plant. These modules continuously

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transfer calculation results to the PLC, providing total

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compliance with the API 21.1 standard.

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The gas then leaves the oil treatment plant and is

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transferred 12 km to the oil extraction plant where

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16 flow computers (MVI46-AFC) calculate the flow

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rates and gas volumes. The MVI46-AFC modules

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communicate through the backplane with an SLC 5/03

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for each extraction plant.

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"Thanks to the interaction between ProSoft's MVI46-

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AFC in-chassis flow computer module and the SLC

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processor, we could implement an automated system

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for calculation and presentation of results totally

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compatible with the level of autojja^^l^Uj^^^w^

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plant," said Aragon. "the cost would have been much

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higher using the classi^ri^BjWted flow comp]tatefs--J

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(EMEDs) than those o^wrTe^hrough the in/ckHs5t>4LLow

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computer module^r

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The flow computer's computation is divided into

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two stages. First, the oil is measured with the gas 'in

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solution.' Then, three 2100-AGA modules transfer the

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results to the PLC data memory where the gas amount

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is subtracted frc/no t/e on volume whicTuis supplied bV/

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the module. This is accomplished by using a correlation

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involving the gas density (also supplied by the module),

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oil density, pressure and temperature.

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^ l \ Uo\tinued

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ASIA PACIFIC

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AFRICA

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EUROPE

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MIDDLE EAST

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LATIN AMERICA

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NORTH AMERICA

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