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Company Chooses In-Rack Flow Computers for Brazilian Natural Gas Operation

 In the heart of this Brazilian rainforest, 38 flow streams of natural gas are transferred to an oil treatment plant. Because of regulations published by the National Oil Agency requiring a better measurement of accuracy for oil volume transfer, the company that owns the plant needed to review its existing installations and specify equipment compliant with these new regulations.

“If we had chosen the classic model of dedicated flow computers (EMED), the costs and the engineering for the presentation of results would be much higher than those obtained through an integrated flow computer, since for the implementation of 68 EMEDs we had an average cost of $40,000 per unit,” said the company’s senior equipment engineer.

Because of the high cost, this was not an option for the company. The equipment engineer then discovered ProSoft Technology’s in-rack flow computers for Rockwell Automation® platforms.

Petrobras Plant

Four modules were installed in an 8-slot Allen-Bradley® PLC to calculate the volume for the 38 flow streams transferred through the oil treatment plant. These modules continuously transfer calculation results to the PLC, providing total compliance with the API 21.1 standard.

The gas then leaves the oil treatment plant and is transferred 12 km to the oil extraction plant where 16 ProSoft flow computers calculate the flow rates and gas volumes. The integrated flow computers communicate, through the backplane, with a Rockwell Automation controller for each extraction plant.

“Thanks to the interaction between ProSoft’s flow computer and the PLC, we could implement an automated system for calculation and presentation of results totally compatible with the level of automation used in our plant,” the equipment engineer said.

The flow computer’s computation is divided into two stages. First, the oil is measured with the gas “in solution.” Then, three modules transfer the results to the PLC data memory, where the gas amount is subtracted from the oil volume that is supplied by the module. This is accomplished by using a correlation involving the gas density (also supplied by the module), oil density, pressure, and temperature.

“The test system for each extraction plant was only possible totally automatically without volume loss because of the ProSoft flow computers and the processors,” the equipment engineer said. “If we had chosen the old solutions using EMEDs, the costs would have been much greater. The ProSoft modules are a success story for us. The integration between the modules along with the flexibility of the PLCs were the decisive factors in that success.”

Learn more about ProSoft Technology’s Integrated Oil and Gas solutionshere.