The purpose of this research was to determine if installing a smaller air compressor could reduce the electrical usage of a large semiconductor manufacturing plant. A 200 horsepower Atlas Copco compressor was installed with the existing 500 horsepower Ingersoll-Rand compressors. Testing was conducted during the regular manufacturing process at MEMC Southwest in Sherman, Texas. Analysis of the data found that installing the new compressor could reduce electrical consumption. The study also found there are specific operational setpoints that allow the compressor to operate more efficiently.

The objectives of this research are the prediction of the thermodynamic behavior of a multi-stage intercooled reciprocating compressor and its progressive loss of performance due to leakage. A theoretical model is developed to simulate the thermodynamics of the compressor system and the lubricating condition and wear of the piston ring pack for a multi-stage intercooled reciprocating compressor. A first law of thermodynamics approach is used to determine the thermodynamic properties of the gas inside the cylinders, the intercoolers and the inlet and discharge manifold. The compressor valves are modeled as single degree-of-freedom, spring-mass=damper systems. The flows through the valves are calculated based on the steady flow equations for equivalent orifices. The lubricating condition of the piston ring pack are determined on the basis of hydrodynamic lubrication theory. The wear of the piston rings is assumed to occur when the hydrodynamic oil film between the piston ring and cylinder bore breaks down. Based on the theoretical model, a computer program is developed. This program is tested on an Ingersoll-Rand Model 242, two stage aircooled reciprocating air compressor. The comparison of the experimental values of the pressure variations in the first cylinder with the value predicted by the computer program shows a reasonable match. The computer program predicts the pressure, temperature and mass flow rates for each cylinder and the intercooler. Also predicted is the wear rate of each piston ring. The progressive loss in the compressor mass discharge, and hence the loss in its performance, is determined by calculating the leakage losses several times, updating the leakage area each time based on the wear rate of the piston rings. The result shows a drop of about 15 percent in the discharge rate of the Model 242 compressor after 8000 hours of running time. / Master of Science

The rigid-body rotational vibration of a resiliently mounted air compressor about an axis parallel to the axis of the rotor is investigated. An analysis of the motion of the compressor base is conducted using empirical acceleration data. The effect on roll vibration of changing various compressor design parameters is studied using a computer simulation program, PABEWE. This digital simulation incorporating slider-crank linkage analysis employs the strict equations of motion. Control theory is used to control the roll vibration. The control theory is applied to simplified equations of motion and incorporates various feedbacks. Recommendations are offered for the reduction of roll vibration levels. / Master of Science

This research introduces a new method of diagnosing the internal condition of a reciprocating air compressor. Using only measured load torques and shaft dynamics, pressures, temperatures, flow rates, leakages, and heat transfer conditions are quantified to within 5%. The load torque acting on the rotor of the machine is shown to be a function of the dynamics (instantaneous position, velocity, and acceleration) of the driving shaft, the kinematic construction, and the internal condition of the machine. If the load torque, the kinematic construction of the machine, and the dynamics of the rotor are known, then the condition of the machine can be assessed. A theoretical model is developed to describe the physical behavior of the slider-crank mechanism and the shaft system. Solution techniques, which are based on the machine construction, crankshaft dynamics, and load torque measurements, are presented to determine the machine parameters. A personal computer based system used to measure the quantities necessary to solve for the machine parameters and the quantities used to compare with calculations is also documented. The solution algorithm for multi-stage compressors is verified by decoupling the load torque contributed by each cylinder. Pressure data for a four-stage two-cylinder high pressure air compressor (HPAC) is used. Also, the mathematical model is proven feasible by using measured angular velocity of the crankshaft and direct measurements of the load torque of a single stage, single cylinder air compressor to solve for the machine parameters. With this unintrusive and nondestructive method of quantifying the operating parameters, the cylinder pressures, operating temperatures, heat transfer conditions, leakage, and power consumption of a reciprocating air compressor can be evaluated. / Ph. D.

För att skapa konkurrenskraft krävs alltid optimering, av flera olika processer, mot mer energi- och kostnads-effektivitet. Anläggningen som används i detta projekt, ett kraftvärmeverk som byggdes så sent som 2015, har dragits med vad som verkat vara en icke optimal drift av tryckluftssystemet med tre identiska, frekvensomformarstyrda kompressorer. Målsättningen med detta projekt var att ta fram förslag på en mer optimal styrning av anläggningens tre kompressorer samt att implementera den för att genomföra en analys om resultatet. En nulägesanalys visade att det fanns utrymme för förbättring av styrningen samt att en del regulatorparametrar skulle behöva optimeras. Två regleringsförslag togs fram, som till stor del vara ganska lika men med den stora skillnaden att förslag ett använda sig av kompressorernas tryckregulatorer och det andra förslaget styrde kompressorernas varvtal direkt från PLC:n. I slutet på detta projektet, när de nya regleringsförslagen skulle implementeras, var anläggningen i ett tre veckor långt driftstopp för underhåll. Detta påverkade optimeringen genom att förbrukningen av tryckluft var låg. Detta skulle lett till att en parameteroptimering inte skulle blivit helt optimal. Eftersom kompressortillverkaren inte valde att samarbeta fanns dessutom ingen möjlighet att utföra en parameteroptimering på alla regulatorer. Trots dessa omständigheter så har en viss optimering troligen skett med det nya regleringsförslaget. / In order to create competitiveness, optimization towards more energy and cost efficiency is always required, of several different processes. The plant used in this project, a cogeneration plant that was built as late as 2015, has been drawn with what appeared to be a non-optimal operation of the compressed air system with three identical air compressors whom are controlled by frequency converters. The objective of this project was to produce proposals for a more optimal control of the plant's three air compressors and to implement it to carry out an analysis of the result. An analysis of the origin operation showed that there was room for improvement of the control and that some controller parameters would need to be optimized. Two regulatory proposals were developed, which to a large extent are quite similar but with the great difference that the first proposal make use of the compressors' pressure controllers and the other proposal controlled the speed of the compressors directly from the PLC. At the end of this project, when the new regulatory proposals were to be implemented, the facility was in a three-week downtime for maintenance. This affected the optimization because the consumption of compressed air was low. This would mean that a parameter optimization would not be completely optimal. Moreover, since the compressor manufacturer did not choose to cooperate, there was no possibility of performing a parameter optimization on all controllers. Despite these circumstances, some optimization has probably occurred with the new regulatory proposal.