Date

2013

Degree Name

BS in Electrical Engineering

Department

Electrical Engineering Department

Advisor

David Braun

Abstract

People depend on electricity all over the world. They depend on it for anything from drying their hair to global communications to heating up food. Many methods of power generation exist, each using a different fuel such as nuclear power, natural gas, coal, wind or the sun. This project focuses on a power plant which uses the naturally hot water in the ground to generate electricity. This process of generating power is called “Geothermal.” This project consists of two parts. The first and major part is the design logic of a PLC program that monitors the flow rate of an injection well using a differential pressure sensor, the pressure and temperature of the water flowing into the injection well. The sensors emit a 4-20mA analog signal that the program translates into engineering units that an operator can understand. The monitoring system program calculates the total flow in gallons over a 24 hour period and sets off alarms in the event of extreme pressures or flow rates. The data from the system continuously gets transmitted through line-of-site radios to the main communication line that sits near a production well. Monitoring the flow rate of the water in the injection pipeline, allow the operators of the plants to know if a leak exists somewhere within the plant, which prevents larger problems. The second part of this project scratches the surface of injection pump control. This equipment operates under high temperatures and pressures, so strict procedures must be followed within the injection pump PLC control program to maintain safety of both employees and equipment. The control description, found in Section III, clearly communicate what the control program must do as a whole. The brine is above boiling point, so the injection pumps must maintain a minimum pressure to remain a liquid. The faster the pumps run the more pressure in the pipeline. The second part of this project uses a boiling point table and the temperature of the brine to calculate the minimum pressure the pumps must maintain in the pipeline to keep the brine in a liquid form. Once that pressure is calculated, existing PLC logic uses that pressure to control the speed of the pumps.

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