2008 Air Quality Regulatory Update
Jim McCarthy, Innovative Environmental Solutions, Inc.
The federal Clean Air Act and State regulations continue to pursue emission reductions from gas industry sources. This annual session on air
regulatory issues will cover the status, content, and potential impact of new U.S. EPA and State air regulations affecting gas industry facilities. Highlights will include key regulatory developments from the last year, including the final federal New Source Performance Standard (NSPS) for gas-fired reciprocating internal combustion engines, which addresses NOx, CO and VOC emissions. Related revisions to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for engines will also be discussed. In addition, the National Ambient Air Quality Standard (NAAQS) for ozone was lowered in March 2008. NOx emissions are regulated as an ozone precursor, and potential implications of the revised ozone NAAQS will be discussed. An update of greenhouse gas (GHG) emissions issues will be provided, including EPA plans to develop a GHG emissions reporting regulation. Each air quality issue will be summarized and related implementation issues will be discussed.
Subjects: Uncategorized
Analysis & Application of Advanced Balancing Techniques for PCC Fitted Pipeline Engines
Matthias Huschenbett & Matthias Brunner – Hoerbiger Service North America / Greg Beshouri – Advanced Engine Technologies Corp. / Markus Dettwyler - Kistler Instrumente AG
Further reduction in NOx emissions can only be obtained by improving engine combustion control at the cylinder level. As part of the ERLE (Emission Reduction for Legacy Engines) task 1c (Cylinder and Cycle Level Control) initiated by the Pipeline Research Council International (PRCI) the combustion performance on different pipeline engines at several air/fuel ratios, speed and loads have been investigated. The evaluation of continuously monitored in-cylinder pressures shows a significant correlation between air/fuel ratio based cylinder balance and combustion stability. Furthermore, the effects of in-PCC air/fuel ratio balance as well as ignition timing have been examined both qualitatively and quantitatively. Based on these findings, cylinder and prechamber balancing techniques were developed which ensured improved operating stability closer to the lean air/fuel ratio limit. The paper will present these advanced balancing methods based on peak pressure, IMEP, heat release, mass fraction burned and corrected trapped equivalence ratio. It will describe the fundamentals behind these methods based on theory and measured data. In addition, the demonstration on a Clark TLA6 engine will be presented. The results will be summarized in a benefit assessment regarding emission reduction, fuel efficiency and operating stability.
Subjects: Uncategorized
Analysis of High-Speed Engine Valve Vibrations Using Statistical Methods
Fred Oliva & John Kealty – Dynalco, Division of Crane Corp.
High-speed engines used in natural gas gathering applications have been shown to have a history of power valve failures. This is especially true for exhaust valves, due to the high temperature environment to which the valve is exposed. Last year, a methodology for analyzing valve closing events using statistical techniques was proposed. Refinements to the statistical techniques used to analyze valve vibration events are discussed. In addition, cause and effect data showing correlation between the statistical analysis and actual mechanical performance will be discussed. This paper will present first-order differences between a nominally healthy valve and one that is potentially approaching failure. The differences are determined using statistical methods and verified by analysis of the actual mechanical components.
Subjects: Uncategorized
Application Guideline for Centrifugal Compressor Surge Control System
Klaus Brun, Ph.D., SwRI; Marybeth G. Nored, SwRI
This guideline was developed through research funding provided by the Gas Machinery Research Council and industry co-funding from BP and Exxon Mobil. The intent behind the development of the guideline is to provide an objective viewpoint on the design requirements and functionality of a centrifugal compressor surge control system. Within the natural gas industry, many different philosophies govern the design of surge control system, including designing for surge prevention, designing for limited surge occurrence under specific “low energy” conditions (based on previous experience), risk-based evaluation of surge control systems (based on a set of risk criteria), and design based on the predictions of transient models (using the results of a transient model to assure adequate protection of the compressor through the surge control system performance). All of these methods are acceptable depending on the installation and provided that the disadvantages of each philosophy are recognized. This guideline does not attempt to prescribe a specific philosophy, but instead to present the necessary information required to make the most suitable choice for the operating company, manufacturer, or designer.
Subjects: Surge Control
Assessment of Knock Characteristics of Alternative Gas Fuels through Methane Number Measurement
Martin Malenshek, Brett Wilson & Dan Olsen - Engines & Energy Conversion Laboratory, Colorado State University
Numerous alternative gaseous fuels are currently being considered to supplement our natural gas supply. These consist of synthetic gas (coal gasification, reformed natural gas) and biomass derived gases (anaerobic manure digestion, bio-mass pyrolysis gasification, landfill methane collection). Published combustion characteristics for alternative gas fuels are limited. A key combustion characteristic for gaseous fuels is the methane number, analogous to the octane number for liquid fuels. Fuel with a high methane number has good knock resistance, while a fuel with a low methane number has poor resistance to knock. More data is needed for alternative gas fuels so engines operating on these fuels can be designed for high efficiency and low pollutant emissions. For this work, methane number measurement is performed utilizing a single cylinder, F-12 Cooperative Fuel Research (CFR) engine, modified for gaseous fuel operation. A fuel blending system is used to simulate documented alternative fuel compositions. A mobile gas collection system is developed for field gas samples of previously untested alternative gas fuels. Methane number measurements of blended alternative gas fuels show an extremely wide range of methane numbers, from 24 (coal gas) to 140 (landfill gas). By comparison, the typical range for natural gas is approximately 80-95. The implications to engine design are discussed. This work was funded by the California Energy Commission.
Subjects: Uncategorized
Automation Upgrades for Compressor Engines
Gavin Goolsbee, Victor Bravo, David Kirschke & Matthew Rem – Hoerbiger Engineering Services
The questions that you ask going into an automation upgrade project are easily as important as the answers provided. What is the reason for the upgrade? What type of unit control philosophy will be used? Where will the unit PLC reside? Here we will cover some different views on these and other questions. We will discuss the basic hardware requirements by exploring some basic panel designs including: area classification, discrete and analog signals, and the instruments that utilize them. After hardware requirements, screen design and some programming philosophy will be discussed. The short course will conclude with a discussion about the need for balance between budget, the wish list, and what is really necessary in your automation upgrade.
Subjects: Uncategorized
Basic Engine & Compressor Analysis
Warren Laible - Windrock, Inc.
The objective of this course is to discuss the use of portable analysis equipment to determine the mechanical condition and performance characteristics on different types of two- and four-cycle engines and reciprocating compressors. The course is designed for engineers, analysts, and personnel who work with reciprocating machinery maintenance, reliability, and optimization. The course will include: a brief review of 2-stroke and 4-stroke engine theory; potential engine faults and the purpose of analysis; explanation of engine measurements (ignition, pressure, vibration, ultrasonic, spectrum/FFT); explanation of engine data, plots and reports; engine case studies; a brief review of compressor theory; potential compressor faults and the purpose of analysis; explanation of compressor measurements (pressure, vibration, ultrasonic, proximity, spectrum/FFT); explanation of compressor data, plots and reports; compressor case studies.
Subjects: Uncategorized
Basic Introduction to Spark Plugs & New Spark Plug Technology
Charles Chewning – Champion Industrial Spark Plug
As natural gas engine efficiencies continue to rise, there is an ever-increasing demand for longer life spark plugs. The design of a spark plug certainly has an important part to play in determining its useful life, and much development is being done to design a spark plug that will last at least as long as the engine service interval. Current production designs are constantly being evaluated for performance and customer satisfaction. These evaluations often highlight a requirement for new designs offering longer life in certain applications. Field testing and customer feedback are part of the continual development process. In addition to spark plug design, many other factors are critical in determining spark plug life. These include cylinder head design, spark plug installation, the ignition system, ignition timing, fuel and combustion chamber conditions.
Subjects: Uncategorized
Basic Thermodynamics of Reciprocating Compression
Greg Phillippi – Ariel Corporation
This short course will cover the fundamental principles of reciprocating compressors and engines. For the compressor, this will include discussions of PV diagrams, capacity, volumetric efficiency, and horsepower. In addition, it will cover the effects of changing conditions, gas analysis, temperature, and pulsation on compressors. For the engine, discussions of the sequence of events for two-stroke and four-stroke engines that include pressure and vibration patterns with respect to volume and time will be presented. Finally, it will briefly cover engine combustion characteristics for a few common cases.
Subjects: Uncategorized
Benefits of the Virtual Orifice: Pulsations & Vibrations Reduced, Performance Improved
Gary Bourn - El Paso Western Pipelines/Buddy Broerman, Robert J. McKee & Marybeth Nored – Southwest Research Institute
Controlling cylinder nozzle resonant pulsations while maintaining acceptable compressor performance has been an issue in reciprocating compressors for the last 50 years or more. The common solution to reduce vibrations and pulsations in the cylinder nozzle was the installation of an orifice plate at the compressor cylinder nozzle flange or welded into the nozzle near the nozzle-to-bottle acoustic junction. Lower efficiencies and higher pulsations are more evident for high speed, high horsepower machines due in part to the higher mean flows and coincidence of the cylinder nozzle acoustic response with lower compressor orders. The GMRC Pulsation Research Program at Southwest Research Institute has developed a pulsation control device as a replacement and improvement upon the commonly installed cylinder nozzle orifice plate solution. The new device is termed the Virtual Orifice. The Virtual Orifice (VO) has recently been installed at El Paso’s Baxter compressor station. Measured field data has shown that the installation of the VO resulted in a significant reduction in pulsations and vibrations related to the cylinder nozzle resonance while noticeably improving the compressor efficiency. This paper will discuss the fundamental issues that the virtual orifice is designed to address. It includes data (vibration, pulsation, and performance) from a field compressor before and after virtual orifices were installed. The paper will explain
and demonstrate the results from the field test of the installation of a virtual orifice on each cylinder of a high speed reciprocating compressor. The field test results will include summaries of the data that describe the vibration, pulsation, and performance improvements that were observed. This paper demonstrates the benefits of properly applied virtual orifices.
Subjects: Uncategorized
Can You Hear Me Now? Compressor Station Noise: What Is It, Where Is It & How Do I Deal With It?
Fred Mueller - Mueller Environmental Designs, Inc./Michael Smith-Hoerbiger Engineering Services
Abatement of noise is becoming a very integral and costly part of natural gas compressor station design. Many times, noise issues and their abatement costs can be a determining factor in whether a site is economically feasible. It is one form of pollution that resistant land owners can target because they know how sensitive Federal Regulators and the courts can be to the issue. We need to install facilities for the public good, but we also need to be sensitive to community needs. With noise sources from intake and exhaust systems, casing noise, piping noise, regulation, measurement, blowdowns, hydraulics, fans, etc. how do we put all this together to determine these costs in the budgeting phase instead of afterthe- fact? How do we design to minimize these costs? The areas covered in this short course will include the following: noise basics; noise sources in a natural gas compressor station; regulations; noise abatement equipment and techniques-pros and cons. Successful completion of this course will give design professionals a better idea of how noise will impact their design, how noise abatement needs will impact the cost of the facilities and how to address compressor station noise issues in the design phase and reduce construction costs.
Subjects: Uncategorized
Characterization of NSCR Performance on Four Stroke Natural Gas-Fueled Rich Burn Engines
Sarah Nuss-Warren, Kirby Chapman – National Gas Machinery Laboratory, Kansas State University/James McCarthy & Thomas McGrath – Innovative Environmental Solutions
Kansas State University’s National Gas Machinery Lab and Innovative Environmental Solutions, Inc. are conducting a project through 2008 to
characterize emissions performance for application of non-selective catalytic reduction (NSCR) technology to four-stroke cycle rich burn (4SRB) engines. BP of America, PRCI, API, the Department of Energy, and Enginuity are providing financial support for the project. Emissions will be monitored over an extended period to characterize the emission levels that can be consistently and reliably achieved, and NSCR operational requirements will be identified. Semi-continuous NOx and CO emissions monitoring systems have been installed on three engines in the Four- Corners area. The systems are installed on 4SRB engines of different makes, models and sizes that use NSCR to control emissions. In addition, ammonia emissions have been tested periodically to understand the emission tradeoff between NOx and ammonia. In addition to these three engines, other engines with NSCR are periodically monitored for NOx, CO and ammonia. Finally, NOx, CO and ammonia emissions were recorded in real-time using an extractive FTIR system, provided by El Paso Corporation, as an engine was operated at various controlled conditions over the course of a few days. All engines included in the study are used in natural gas production. This paper discusses project results to date on emissions characterization of NSCR-equipped natural gas production engines using semi-continuous monitoring. It also describes emissions tradeoffs between ammonia, NOx and CO for NSCR-equipped engines and discusses NSCR implementation and operation.
Subjects: Uncategorized
Combustion Sensing in Pre-Combustion Chambers Using Ion Sense
Greg Beshouri – Advanced Engine Technologies Corp./Matthias Huschenbett - Hoerbiger Service North America
Further reduction in NOx emissions can only be obtained by improving engine combustion control at the cylinder level. This requires cylinder level sensors capable of continuously monitoring combustion performance in both the main chamber and the pre-combustion chamber (PCC). Until recently, in-PCC combustion measurements were only possible in the laboratory using very expensive pressure sensors with extremely short lives. Ion Sense now offers a more robust and cost effective method to monitor in-PCC combustion. Derived from automotive technology, Ion Sense utilizes post ignition ionization measurements from a standard spark plug. When measured from a spark plug mounted in a pre-combustion chamber, Ion Sense provides a wealth of previously unavailable information on flame initiation, early flame propagation, in PCC air/fuel ratio, etc. As part of the Pipeline Research Council International’s (PRCI) Emission Reduction for Legacy Engines (ERLE) Task 1e project, a Hoerbiger lead research team investigated the use of Ion Sense data collected in the PCC to monitor and control in PCC air/fuel ratio, main chamber air/fuel ratio control and the optimal control of combustion timing in both. This paper will report on the results of this testing and review the potential feasibility and benefits of applying Ion Sense based monitoring and control of PCCs for pipeline engines both for research on continuous performance monitoring.
Subjects: Uncategorized
Compressed Air Systems for Natural Gas Compressor Stations
Michael A. Smith, PE - Hoerbiger Engineering Services
As a complement to previous short courses on compressor station ancillary equipment, this course will address the basics of a compressed air
system in a natural gas compressor station. While it is usually considered a minor utility in a compressor station, compressed air systems play a vital role in the reliability of a station. Without starting air and turbocharger jet assist, some stations cannot be brought on line. Stations with pneumatic ESD systems will shut down if the air system is not designed appropriately – or may not be able to shut down – depending on the type of system used. Clean dry air for instrument air or buffer air for turbine dry gas seals are equally important. And, of course, the need for air to operate power tools is always nice to have at a compressor station. The areas to be covered in this short course will be: (1) Basic understanding of the dynamics of compressed air; (2) Uses for air in a natural gas compressor station; (3) Typical equipment for a compressed air system; (3) Equipment layout for a compressed air system. Successful completion of the course will allow design personnel to create more detailed specification sheets, better analyze the proposals and track down problems in a natural gas compressor station system.
Subjects: Uncategorized
Compressor Design for Pulsation & Vibration Control
Christine Scrivner, Dennis Tweten & Ben White - Southwest Research Institute
This short course will discuss the fundamentals associated with pulsation and vibration problems in reciprocating and centrifugal compressor piping systems. The course will include practical and real-world modifications that can be made to improve piping system pulsations and vibrations, both for new and existing compressor units. The short course will utilize the 30 years of design experience established by the GMRC Design Facility. The piping design staff will provide field tested applications of the theory behind pulsation and vibration control. This short course will improve the attendee’s ability to identify and resolve potential or existing problems associated with piping system pulsation and vibration problems. The course will help attendees to anticipate necessary design changes to compressor piping systems.
Subjects: Uncategorized
Compressor Package Design Optimization
Russ Barss - Beta Machinery
Compressor Package Design Optimization
Subjects: Uncategorized
Jim Rauh, Compressor Engineering Corp.
The Cost of Lost Gas
Subjects: Uncategorized
Heathcliff Howland - OSIsoft, Inc. & Pamela McNeil – MichCon
Analogous to the way our industry’s physical energy infrastructure enables natural gas flow from source to consumer, a software infrastructure for managing time-series data and events enables information delivery from a pipeline company’s asset base to its business. In an era of $8gas, increasing compliance complexity and pressure to increase reliability and throughput, gas pipeline companies are looking to bridge the gap that exists between their process automation systems and their business decision and reporting systems. Companies like MichCon are meeting these challenges by mastering the collection, storage, presentation and analysis of high-fidelity fleet performance data through the application of massively scalable industrial data management software. This paper examines the 2008 deployment of Enterprise class historian software at one MichCon compressor station and at their Gas Control headquarters. The system was used to continuously record and store operating data from nearly every piece of station equipment in real-time, including compressor engines and auxiliaries, dehy, flow measurement and gas quality measurement systems. The same software was used to record and store operating data from SCADA and other critical pipeline applications at Gas Control headquarters. Access to this asset data was provided across the organization using desktop and web based tools to drive MichCon energy management, asset optimization, reliability, and compliance initiatives. The paper will include an examination of specific improvements to pipeline operations that were a direct result of the project.
Subjects: Uncategorized
Demonstration of Efficient Pulsation Control Using Tuned Loop Networks – GMRC Research Review
W. Norman Shade, PE – ACI Services; Glen F. Chatfield, Optimum Power Technology
Traditional compressor pulsation attenuation systems are carefully designed combinations of primary and/or secondary volume bottles, often with complex internal choke tubes, baffles, and chambers, as well as various orifice plates installed at specific locations in the system piping. These devices accomplish pulsation control by adding resistance, or damping, to the system; and they result in additional system pressure losses upstream and downstream of the compressor cylinders. These pressure losses reduce the overall system efficiency, but the trade-offs are tolerable for most compressor applications. However, for common pipeline transmission applications having low pressure ratios (in the range of about 1.1 to 1.6), system pressure losses can noticeably degrade the overall operating efficiency, especially with the use of higher speed (>600 rpm) compressors. Using finite amplitude wave simulation technology, the application of tuned pulsation attenuation networks on reciprocating compressors was investigated in detail. As reported in a 2007 GMC paper, the computer models and simulations showed that properly configured multiple tuned pulsation attenuation networks could be an effective means of controlling compressor pulsations with little or no resultant system pressure loss. The next step in the validation of this promising concept has been to design, build, and test an actual system for experimental evaluation under controlled laboratory test conditions. This new paper reports the results of a two-loop attenuation network configured on a 500 to 1050 rpm air compressor arrangement having four 4 in. diameter, 3 in. stroke single acting ends that effectively behave as two double-acting cylinders operating in parallel. Test results are compared with predictions showing the effective cancellation of pulsations with minimal system pressure drop. Further,
the paper describes the design of a tuned pulsation attenuation network that will be retrofitted and tested on an actual 750 to 1000 rpm, 6 in. stroke compressor in a natural gas pipeline compressor station.
Subjects: Uncategorized
Development of a Surge Control Guideline & Surge Testing Considerations
Augusto Garcia-Hernandez, Marybeth Nored & Melissa Wilcox – Southwest Research Institute
Under the 2007 GMRC Program, Southwest Research Institute developed an application guideline to be used in the design and selection of
centrifugal compressor surge control systems. A surge control system should function to protect the compressor from surge during start-up, normal process control and shutdown. The shutdown process includes both controlled and emergency (ESD) events. As a common reference for users, surge control system designers, and compressor manufacturers, the guideline is intended to provide a common reference on selection of system components and design for functionality in three distinct operating environments. The guideline enhances the understanding of surge control system design to improve performance and reduce unnecessary cost. This paper will discuss the key points of the surge control guideline as well as the recommended design criteria which provide a means of determining if the surge control system will meet expectations. The paper also discusses recent testing at the SwRI Metering Research Facility to develop a set of compressor surge data. In addition, an experimental methodology for surge testing is presented as a part of the GMRC 2008 Research Program that seeks to complement the surge control system guideline. Results from the surge testing may be utilized to verify recommendations of the guideline.
Subjects: Uncategorized
Downtime Reduction on Reciprocating Compressors with Heat-Free Hub Design
James H. Anderson, III - Coupling Corporation of America
Reciprocating compressors are a notoriously high stress application, especially when being driven by a diesel engine. The torque pulsations are enormous, and the torsional vibrations can be fatal to equipment. Therefore, the shafts in these compressors are very large to compensate for the high stresses. Some manufacturers have realized that one method for reducing stress is to eliminate the keyway. Without the keyway cut into the shaft, there are no stress risers that can lead to cracks. Another advantage of not using a keyway is the ability to make the shaft diameter smaller while maintaining the same stress level. Keyway or no keyway, the coupling hub still needs to carry high torques with a large service factor (at least 3) without slipping or breaking the shaft. In the case of keyless shafts, the shrink fit is usually tighter than in the keyed case.
Subjects: Uncategorized
The Dynamics of Reciprocating Compressor Valve Springs
Glenn Hatch & Derek Woollatt - Dresser-Rand Company
The valves in reciprocating compressors use springs to control the timing of the valve closing. These springs are subjected to dynamic loading by the motion of the valve element. The element motion is periodic but includes rapid acceleration and deceleration. It can therefore excite a wide range of frequencies in the spring. The resulting spring surge creates high stresses and is a major contributor to premature spring failure. Valvefailures are the most common reason for unscheduled compressor shutdowns. The valve springs are the most common source of these valve failures. Therefore, valve spring life is of utmost importance in attaining increased compressor reliability. This paper discusses two approaches to calculating the spring stresses caused by the surge. The first is an approximate method that considers only torsional deflection of the spring wire and neglects end coil effects. The second is a more complete analysis that uses both kinematics and FEA simultaneously to replicate the spring’s response to the dynamic loading. The results of the two methods are compared and their usefulness in preventing spring failures is discussed.
Subjects: Uncategorized
Martin Hinchliff- Dresser-Rand
The Effect of Compressor Cylinder Design on Nozzle Pulsations: Field Test Results of the Dresser - Rand DDV Pipeline Cylinder
Subjects: Uncategorized
Jisang Sun, Al Weber, David Yellowhair & Dan Halvorson – Cummins Natural Gas Engines, Inc.
Engine and catalyst emissions testing were conducted on the Cummins G5.9E, G8.3E and the GA855E stoichiometric engines under development
to meet the 2008 NSPS 1048 EPA requirements for engines (2g/bhp-hr NOx, 4g/bhp-hr CO, ad 1g/bhp-hr VOC). The test periods ranged from 2,000 to 4,000 hours at rated or overload conditions. Periodic emission measurements were taken with a four-gas portable analyzer. Test conditions were subject to ambient changes (i.e., temperature, humidity, and variation of pipe line gas constituents). During testing, core samples from the catalyst were collected and sent to the catalyst manufacturer for the determination of deterioration effects. Results indicate that the engine control algorithm was robust and did not require adjustment for the test period. The testing also gave insight into the engine/catalyst deterioration rate and the need for periodic calibration of emission analyzers with certified calibration gas.
Subjects: Uncategorized
Joe Minlot - Compressor Engineering Corp.
eMAX mini Poppet Valves
Subjects: Uncategorized
Empirical Compressor Performance Maps for High-Speed Multi-Stage Compressors
Bob Webber – Dynalco, Division of Crane Corp.
High-speed compressor packages used in natural gas gathering applications have not historically been subject to the scrutiny of field performance mapping and equation development. In recent years the criticality, size, and volume moved by such compressors has made it economically justifiable and profitable for operators to have more and more accurate maps. Experience with a tried and true field methodology used in natural gas transmission applications and the changes needed for gas gathering are discussed here. The results of this activity show that theoretically generated curves can predict horsepower and flow, either low or high by as much as 20%. Several fundamental differences in control and operation required special attention and changes to the testing protocol. Although more challenging than transmission applications, empirical methods do work in field gathering high speed, multi-stage applications. Given the cost of gas and value of gathering contracts, small improvements in the operation of high speed field compressors makes empirical mapping not only viable, but desirable. High speeds present some different challenges to the field engineer but with persistence and proper tools these challenges can be met.
Subjects: Uncategorized
Evaluation of KTA19-GC Engine Performance on Low-BTU Gas
Tim Newell - Cummins, Inc.
Evaluation of KTA19-GC Engine Performance on Low-BTU Gas
Subjects: Uncategorized
Dave Bell, Altronic, Inc.
EZ Rail
Subjects: Uncategorized
Gas Turbine & Centrifugal Compressor Field Test Software Development
Timothy C. Allison, Marybeth Nored & Klaus Brun - Southwest Research Institute
Gas Turbine & Centrifugal Compressor Field Test Software Development
Subjects: Uncategorized
How a Centrifugal Compressor Works
Rainer Kurz - Solar Turbines Inc./Klaus Brun – Southwest Research Institute
Centrifugal compressors are widely used to compress gas in industrial applications. This short course will address the general principles of gas compression and explain the theory behind the concepts of compressibility, head, and efficiency. Also, the importance of the interaction between the compressor and the system will be discussed. In a second part, the working principles of centrifugal compressors and their operational characteristics are explained. We will also discuss the components of centrifugal compressors required to make the compressor function. The third part of this short course will give an overview of different drivers for centrifugal gas compressors, including gas turbines and electric motors of various configurations. We will focus particularly on the interaction between the driver characteristics and the compressor and system characteristics.
Subjects: Uncategorized
A Method for an Alternative Flow Measurement in a Centrifugal Compressor
Michael J. Cave & Rainer Kurz – Solar Turbines Inc.
Measuring the flow entering a centrifugal compressor is critical for process control, condition monitoring as well as for the protection of the compressor from surge. Usual methods (such as orifices, ultrasonic flowmeters and others) may cause permanent pressure losses, may be costly, or deliver weak, noisy signals. By using the natural acceleration found in the inlet of a centrifugal compressor, a built-in flow measurement can be incorporated into the machine with non-intrusive static pressure taps. This measurement can be used by the package PLC to determine compressor flow rates and can be used for process and surge control, thus reducing the need for orifice plates. By removing orifice plates from the compressor station, improved operating efficiency can be realized through reducing station piping head loss. While other non-intrusive flow measurement devices exist, all are external to the compressor and must be purchased separately at significant cost. By measuring the natural pressure drop from the inlet flange to the inlet of the impeller, correlations to standard flow nozzle measurements can be made. Correlating this pressure data to standard flow measurement devices installed during the factory test allows a flow calibration to be established. This paper describes the theory in using the natural pressure drop that occurs in the inlet system of a centrifugal gas compressor as a flow measurement reading. It further explains the cost savings to end-users in both first cost and operating costs compared to independent flow measurement devices. It also describes their use as both a primary flow measurement as well as surge control. Comparisons to independent flow measurements and application history are also made.
Subjects: Uncategorized
Kriss McDonald- Ariel Corporation
A New Compressor Valve
Subjects: Uncategorized
Hans Mathews - Hoerbiger Engineering Services
New Products
Subjects: Uncategorized
New Solutions for Trubocompressor Machinery Availability Improvement
Jeremy Barnes - GE Oil & Gas, Global Services
New Solutions for Trubocompressor Machinery Availability Improvement
Subjects: Uncategorized
New Technologies for Fuel Economy & Emission Reduction in SI Engines
M. Reza Azizian, Hossein Assefi & Navid Salarvand - Eastern Mediterranean University
In the 21st Century, a majority of both engine and vehicle development is concerned with environmental laws pointed primarily towards the limitation and control of engine emissions. Increasingly stringent emissions and fuel economy standards have long remained a source of challenges for research in automobile engine technology development towards the more thermally efficient and less polluting engine. The Exhaust Gas Recirculation (EGR), Variable Compression Ratio (VCR) and Variable Valve Actuation (VVA) are the known ways for improvement of fuel economy, emission and performance. There is a high potential in reducing the exhaust emissions, especially NOx emissions by EGR, a principle technique used to control the SI engine NOx emission. A fraction of the exhaust gases is being re-circulated through a control valve from the exhaust to the engine intake system. The re-circulated exhaust gas usually mixes with the fresh fuel-air mixture just below the throttle valve, mainly as a result of reduction in the maximum combustion temperature. The level of NOx production is very sensitive to this temperature (this, incidentally, has discouraged the development of the so-called adiabatic engine in which fuel economy is improved by reducing in-cylinder heat losses). The higher compression ratio leads to the higher SI engine efficiency. The fuel economy and efficiency of SI engines has been improved by the VCR technique. In order to vary the compression ratio, some methods of varying the geometric compression ratio through changing the clearance volume is required. Modification of the compression ratio is being done by moving the cylinder head, variation of combustion chamber volume using a secondary piston or valve, variation of piston deck height, modification of connecting rod geometry, moving the crankpin within the crankshaft, and moving the crankshaft axis. Varying the engine valve-open duration, lift and phasing are known ways to improve engine performance, increase fuel economy and lower emissions. In traditional internal combustion engines, valve timing is fixed relative to crankshaft angle and piston position, allowing engine performance to be optimized at only one engine speed. If engine valve timing and lift profile were flexibly controlled by a variable valve actuation system, significant improvements in fuel economy, engine performance, and emissions can be achieved. In this study, the underlying process of EGR, VCR and VVA techniques are thoroughly presented. Moreover, a comprehensive comparison between the mentioned techniques is presented in order to have a convenient selection from the emission reductions, fuel economy and efficiency point of view.
Subjects: Uncategorized
Operating Characteristics of an NSCR Catalyst on an 80 kW Cummins-Onan Genset
Sule Amadu & Dan Olsen - Engines & Energy Conversion Laboratory, Colorado State University
Non-Selective Catalytic Reduction (NSCR) can be an effective means for emissions control for engines that operate at stoichiometric air-fuel ratios(“rich” burn engines). NSCR catalysts simultaneously reduce NOx, THC, CO, and formaldehyde (CH20) when the equivalence ratio is controlled within a narrow operating range. When the equivalence ratio falls outside the operating range, emissions reduction efficiency for one or more constituent will be poor, and excessive ammonia (NH3) formation in the catalyst can occur. In this paper, the operating characteristics of a commercially equivalence ratio (0.99-1.05), space velocity (20,000/hr-430,000/hr), and catalyst temperature (350oC-600oC). Catalyst performance for all constituents (NOx, THC, CO, and CH20) is examined at the NOx-CO efficiency cross-over point. The maximum NOx reduction efficiency and maximum NH3 emissions are determined at rich equivalence ratios. The effect of space velocity and temperature on the above performance parameters is discussed. The required equivalence ratio control band to meet current and pending regulations is assessed.
Subjects: Uncategorized
The Parabolic Burning Curve Explained
Randy Anderson – ACTT, div. of CECO
The parabolic burning curve is one of the most important tools for understanding basic engine combustion and performance. The parabolic burning curve describes the relationship between air/fuel ratio and various engine parameters affected by combustion. This paper will describe theimpacts of air-fuel ratio on exhaust emissions, peak firing pressures, oil analysis, misfires, detonation, fuel economy, and a variety of other related engine performance indicators. This paper is recommended for engineers, analysts, mechanics, emission testing personnel, and anyone who is involved with tuning or adjusting engine parameters to improve performance and reliability.
Subjects: Uncategorized
Performance Control of Reciprocating Compressors: Devices for Managing Load & Flow
Chad Brahler, Norm Shade & Dwayne Hickman – ACI Services, Inc.
This course aims to provide attendees with the knowledge to fundamentally understand the various types of unloading and capacity control devices, the ability to decipher product claims, and the skills to identify methods and equipment used to modify unit performance relative to their needs and budgets. Useful, and unbiased, comparisons between the various performance control devices are detailed via provided quick-referencecharts. Additional information provided includes: diagrams, pictures and schematics; advantages and disadvantages; performance considerations; operational limitations; practical applicability. Upon course completion, attendees will be able to identify best possible means to achieve optimum
performance control for both current and new units. Furthermore, participants will gain valuable knowledge that can be readily implemented when considering the full economics of real costs versus return on investments.
Subjects: Uncategorized
Rich Frogge - Direct Drive Ststems
Permanent Magnet Synchronous Motor Technology & Its Advantages Over Conventional Motor Drive Solutions
Subjects: Uncategorized
The Physics of Pulsations in Reciprocating Compressor Stations
Klaus Brun & Marybeth Nored - Southwest Research Institute
For the last 50 years the natural gas industry has relied on acoustic analysis tools to determine piping system resonances for reciprocating compressor stations. This was initially accomplished using an analog electric circuit simulation where essential compression station elements were simulated using function generators, resistors, capacitors and inductors. Conveniently, the transient acoustic wave equation was simulated based on the functionally identical governing equations of electric circuitry. Later in the 1990s, this technique was improved upon by the application of digital computer simulations of the acoustic wave equation using numerical solver algorithms. However, both approaches did not solve the actual fluid dynamic equations of pulsating flow in pipes, but rather solved a linearized, acoustic (low pressure perturbation) equation. The classic wave equation solution is based on a number simplifying assumptions which include no mean through-flow, infinitely small pressure pulsations, equally small variations in acoustic density, no viscosity, and quasi-constant gas properties. Incorporation of linear attenuation terms will further distort the accuracy of the linear, acoustic model. These assumptions sufficiently simplify the equation to allow for superposition (simple summation of sources) and a fast solution for the resonant frequencies of complex piping systems. Unfortunately, these assumptions also severely limit the acoustic wave equation method’s ability to provide correct predictions of high pressure pulsation magnitudes. For variable-speed high-rpmmachines, where resonance will inevitably occur due to overlapping speed bands, accurate prediction of pulsation magnitudes is critical to the design process. Specifically, as pulsations in real piping systems tend to be large (>1% of mean pressure) and have a mean flow component, the inertial transport terms and the viscous terms of the governing equations must be included in the analysis to prediction transient dynamic pressures.
This paper compares the mathematical assumptions of acoustic wave equation solvers with those of a fully fluid dynamic model. The paper
also presents case studies to demonstrate the difference in pulsation predictions between acoustic models and full fluid dynamic models. The two
models prediction of pulsation amplitudes – pulsation wave form and resulting frequency spectrum distributions are discussed.
Subjects: Uncategorized
Pre-Detonation, Natural Gas Engines that Act Like Diesels
Keith Schafer - Columbia Gas Transmission
This paper will show a unique type of combustion on two types of natural gas engines. Case Study One is a Cooper Bessemer 8W330 that had
severe detonation on startup. Over a 20-year period, this unit has had severe detonation until the engine water and oil temperatures got high enough for the by-pass to close and load the engine. Running at full load and speed, the detonation went away. This unit has broken over $2 million in pistons, cylinders and heads in the past 20 years due to the detonation. After three turbochargers, new air/fuel ratio controls and a lot of programming, the problem would not go away. Memorial Day 2004 the engine would not start and the equipment analyst was called. Checking the firing pressures on the power cylinders as the engine started, it was noticed that the loud noise from the power cylinders was not detonation. Case Study Two is from a Dresser-Rand TLA-6 with aftermarket pre-chambers which were installed in the mid 1990s. After several other changes and controls were added, the unit had severe detonation on startup. Normal thinking to reduce detonation is to retard the ignition timing to build heat in the turbocharger to make more air. This did not work. After checking the firing pressures on startup, it was discovered we were treating for detonation and the problem was pre-detonation. The presentation explains the differences of these types of combustion, detonation, pre-ignition and the very rare pre-detonation.
Subjects: Uncategorized
Precombustion Chamber Design for Low NOx Emissions from Large Bore NG Engines
Dean Simpson & Dan Olsen – Engines & Energy Conversion Laboratory, Colorado State University
Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines enabling increased combustion stability while
extending the lean limit of operation. In this work the role that the PCC plays in the formation of oxides of nitrogen (NOx) is investigated. Additionally, new PCC designs are explored as a means for reducing engine-out NOx emissions. Previous research indicates that the PCC is responsible a significant portion of engine-out NOx, especially near the lean limit of engine operation. Experimental results from a large bore lean burn 2-stroke cycle engine are presented. The data shows that the PCC is responsible for a significant part of engine-out NOx emissions. However, the results indicate that the PCC NOx does not form in the PCC. Rather, the results show NOx forms within the gas jet after it penetrates into the main chamber combustion gases. Five PCC concepts are developed in the scope of reducing NOx. A test plan is created to compare the baseline PCC configuration to the performance of the new PCC concepts. Three of the concepts demonstrate improved combustion stability while reducing engine-out NOx. A PCC flow model is created to better understand PCC operational characteristics. The research was funded by the Pipeline Research Council International (PRCI).
Subjects: Uncategorized
Predicting Engine Pressure-Time Patterns
Manny Angulo – ACTT, div. of CECO
This paper presents a set of equations that can be utilized to predict the pressure time pattern for a complete cycle of events on an engine. It starts with the various physical relationships and operating parameters that must be known, and then covers the development of equations that describe the pressure time relationship throughout the cycle of events. These equations are combined to form a complete pressure time pattern and then the various inputs can be modified to determine changes in the pattern.
Subjects: Uncategorized
Pulsation & Vibration Control Strategies to Meet the New 5th Edition of API 618
Shelley Greenfield, Chris Harper & Kelly Eberle - Beta Machinery Analysis
API 618 5th Edition applies to reciprocating compressors. The new edition was released in the industry, including high speed machines, as the
standard specification to avoid vibration problems and ensure high reliability. This short course outlines the key changes in the new standard, compared to the 4th Edition which was published in 1995. Topics include: brief background on pulsations, vibration, resonance and mechanical design; changes to pulsation analysis guidelines and the implication to controlling pulsation forces; discussion on cylinder stretching forces and other forces affecting the reciprocating compressor; mechanical design strategies to meet Design Approach 3 guidelines; identify key issues for high speed reciprocating compressors, including margin of separation criteria; implication to torsional vibration, dynamic skid design, and piping system flexibility (thermal); application examples for determining which API 618 study is appropriate.
Subjects: Uncategorized
Redesign of the Superior CleanBurn 825 Prechamber & Performance Gains
J.V. Serve' - Cameron's Compression Systems
Redesign of the Superior CleanBurn 825 Prechamber & Performance Gains
Subjects: Uncategorized
Reducing the Total Cost of Ownership of Natural Gas Engines
Kevin McKenna - ExxonMobil Lubricants & Petroleum Specialties Co.
This presentation/publication will show how to reduce operational/maintenance costs for stationary natural gas engines used in the power generation and natural gas industry. It will cover details that operation and maintenance personnel should consider to maximize the return on their investment. This presentation will cover the OEM recommendations, selection of the proper lubricant, why deposit control is important and how to extend oil drain internals.
Subjects: Uncategorized
Reducing the Total Cost of Ownership of Natural Gas Engines
Kevin McKenna - ExxenMobil Lubricants & Petroleum Specialties Co.
Reducing the Total Cost of Ownership of Natural Gas Engines
Subjects: Uncategorized
Specifying, Operating & Troubleshooting Separators
Jay Stell & Tony Walton - Burgess-Manning, Inc.
This short course will present the key factors related to specifying, operating, and troubleshooting the separation equipment used in the gas
compression industry. Of primary interest will be separators that remove liquid droplets and/or solid practices from a gas stream. The source will begin by offering a summary o the various types of separators and the applications to which each is best suited. It will also present the main process parameters needed in order to specify a separator and how each parameter impacts the design and performance of the separator. The course will then cover the operation of separators including hardware, accessories, features, and configurations that are common to separators in the gas compression industry. Finally, there will be a discussion of troubleshooting separators that are not performing as required. This portion of the course will provide a brief summary of common problems and their symptoms. In addition, potential solutions for many common problems will be presented and discussed.
Subjects: Uncategorized
Suggestions for Career Enhancement
James R. Hutton, PE – Compressor Engineering Corp.
Virtually all engineers and technical individuals are very capable in their disciplines but to advance, they must compete in a strong, competitive, and crowded environment. The Mechanical Engineers are brilliant. The Chemical Engineers are exceptional in their field. The Civil and Electrical Engineers are all excellent. What distinguishes a technical person, makes him stand out, and enables him to move up in management are not always his technical skills but instead his people and communication skills. This presentation offers hints and suggestions for professional people to enhance their chances of promotion by enabling them to improve and to hone their people skills by better communication, better letter writing, and sending out the right signals.
Subjects: Uncategorized
System Performance Affected by Dynamic Pressure Drop
Kelly Eberle & Gordon Sun – Beta Machinery Analysis/Dwayne Hickman – ACI Services, Inc.
Industry practice for compressor performance modeling is to make generic assumptions about pressure drop through the piping system. These assumptions can lead to large errors in the calculated compressor performance resulting in the compressor not meeting the original design requirements for capacity. Analytical tools are now available to accurately calculate the static and dynamic pressure drop through all components of the system. Therefore, the compressor application design can be verified in the design stage, thus avoiding costly redesign or retrofit after installation. A number of case studies will be used to illustrate the impact dynamic pressure drop can have on the system performance. This paper will describe the analytical tools used in accurately calculating the system static and dynamic pressure drop. The effect of dynamic pressure drop on the compressor performance will be demonstrated. A design approach will be recommended to ensure the compressor is designed appropriately for the application.
Subjects: Uncategorized
Testing of a Semi-Active Valve for Reciprocating Compressors
Klaus Brun – Southwest Research Institute/Kevin Durham - Cook Compression/John Platt & Meron Wollie – BP
The single largest maintenance cost for a reciprocating compressor is compressor valves. Valve failures can primarily be attributed to high-cycle fatigue and sticking of the valve plate resulting in excessive plate impact velocities. Thus, controlling the valve plate motion and impact velocities can greatly increase the life of a valve while also allowing for improved capacity control of the compressor. A new valve concept, developed under a GMRC program by Southwest Research Institute and Cook Compression and co-funded by BP, uses electromagnetic actuators to control the valve plate motion and create a soft landing at both the valve seat and guard. This concept is referred to as a “semi-active valve” (SAV) since, although the valve still relies on gas forces for the plate to move, the device senses and then controls the plate motion using electromagnetic coils. The SAV development program has evolved and matured through three prototype devices each of which have been tested at Southwest Research Institute. This paper discusses the SAV product development process, laboratory and field testing logistics, site preparation, test execution, and test results. Measurement data for plate impact velocities from the field test will also be presented.
Subjects: Uncategorized
Three-Dimensional Vibration Absorber to Eliminate High Vibrations in Pipelines
Johann Lenz - KOTTER Consulting Engineers KG
Various methods can be implemented to reduce high pipeline vibrations in finished plants. The basic vibration reduction measures available when the cause of the vibration cannot be reduced further include the isolation, dampening, or absorption of the vibration. The design and use of a newly developed, dampened three-dimensional vibration absorption system (Magic Cube) for pipeline vibrations will be illustrated in the paper based on an example case study. Based on the measurement of the actual, high vibrations on the pipes in a natural gas compressor plant, the realization and implementation of the absorber system will be described after explaining the theoretical background.
Subjects: Uncategorized
Using Infrared Thermography to Identify & Account for L&U
Mark Sproull – Enogex
This paper will give detailed information on an Infrared Analysis Program being used to identify natural gas leaks on compressor packages and
in compressor stations. It will include brief descriptions of methods to find and report gas loss in many compressor station components including the following; packing leaks, compressor valve leaks, relief valve leaks, valve deactivator leaks, control valve leaks, piping leaks, and gasket/ seal leaks. An explanation and comparison of different infrared equipment types and programs will be covered, included cost and pay-out with examples of each.
Subjects: Uncategorized
Charles E. Ely, Jr. PE – ACTT, div. of CECO
This course teaches the basis concepts of crankshaft web deflections readings and interpretation. Upon completion, each student will understand the theory and purpose of web deflections; the steps and procedures required to take web deflections; and how to interpret web deflection data musing the WebMap2 software. The course is divided into the following lessons: Introduction to web deflections; Collection of web deflection data; WebMap2.0 software use; WebMap2 web deflection interpretation This course is intended for equipment operators and mechanical personnel responsible for monitoring, measuring, and interpreting crankshaft web deflection data. WebMap is based on original development work by Ray W. James, PE, PhD, with further development performed as part of the GMRC Research Program.
Subjects: Uncategorized
Kirby Chapman & Diana Grauer – National Gas Machinery Laboratory, Kansas State University
This paper presents results from Phase 2 of the development of an active air control system to balance air flow into each cylinder of a turbocharged engine system, a PRCI-funded emissions reduction project. Imbalance in air flow creates a discontinuity in trapped equivalence ratio from cylinder to cylinder. Trapped equivalence ratio is directly proportional to NOX production and a function of the fuel flow rate, air flow rate, and, in a two-stroke cycle engine, the scavenging efficiency. Only when these three characteristics are balanced cylinder to cylinder will the combustion and the NOX production in each cylinder be equal. The engine NOX production will be disproportionately high if even one cylinder operates less lean relative to the other cylinders. This paper reports on the testing of an active air controller on a two-cylinder air flow bench at the National Gas Machinery Laboratory at Kansas State University. The results from these tests were then used to further validate the comprehensive, variable geometry, multi-cylinder flow model referred to as the Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS). CAIMENS is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle- resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has been validated with data from the NGML multi-cylinder flow bench. This information has allowed the research team to (1) quantify the impact of air flow imbalance and (2) provide detailed information leading to the specification of the air flow sensor-actuator system. The end point of this project is an active air flow control specification that can, with some engineering effort, be applied to field engines.
Subjects: Uncategorized
Waste Heat Recovery for Pipeline Compressor Stations
Hans Mathews & Michael Smith – Hoerbiger Engineering Services/Lyndall Keene – Revack Corporation
This paper delves into the waste heat recovery potential and viability for application to gas pipeline drivers, both centrifugal and reciprocating. Most reciprocating engines in the gas pipelines have thermal efficiencies of 35% or less. Simple cycle gas turbines are even less efficient. I the 60s and 70s, several companies set up either electric co-generation facilities or steam driven compressors in an attempt to capture some of this lost energy. However, the high cost of providing the necessary water and the operating and maintenance costs of the steam plant equipment proved more expensive than just operating an additional gas fired unit and most of these facilities have been shut down as uneconomical. An important factor in the economic analysis was that fuel gas was often considered “free” as it was retained as a percentage of transport and any saving would ultimately have to be given back to the customer. The operating environment in the 21st Century is dramatically different. Today, we face increasing demand and ever tightening emissions requirements. In many cases, the emissions generated by incremental horsepower increases have to be offset with emissions reductions at existing facilities. Further, fuel gas is no longer universally “free” and future legislation addressing greenhouse gas emissions will require fleet wide improvements in fuel economy. These drivers bring new opportunity for small waste heat recovery plants operated in conjunction with pipeline facilities. Operationally, there have been dramatic improvements in water treatment technologies and steam plant technologies that promise to make small steam plants more affordable to operate. Further, non-utility owned co-generation facilities are now wide spread, providing a clear path for selling excess power back to the grid. Complementing these developments is the recent availability of a wide range of electric driven pipeline compression equipment. Today, there is a real opportunity to directly use co-generated electricity for compression or simply sell it to the grid. This paper explores three cases for typical pipeline drivers. It details the major equipment
needed, the approximate cost and potential rate of return for the applications. Attendees and readers should get a good feel for the opportunity and have a solid grasp of what market drivers to look for when assessing compression selection.
Subjects: Uncategorized
