The development of highly compact and energy-efficient systems is critical for world energy security and technology leadership. Due to the abundance of natural gas, the natural gas fueled distributed energy systems that lower the energy consumption and utility costs would be ideal in the U.S. as well as worldwide markets. To meet these objectives, researchers from Enginuity Power Systems (EPS) are currently working on the development of an ultra-efficient Combined Heat and Power (CHP) system for residential and commercial applications. These CHP systems generate electricity at the point of use while also meeting the space and water heating demands. Furthermore, a single CHP system replaces the conventional electricity generator, space, and water heating systems in residential and commercial applications. The main technical objective of this research article is the demonstration of the fundamental design and performance characteristics of an EPS’s 6 kW–10 kW CHP system intended for residential applications. The proposed residential system utilized a mirror-balanced, patented, inwardly opposed piston, four-stroke internal combustion engine as a prime mover. This novel four-stroke opposed piston design resolved the scavenging, cooling, and lubrication issues faced by the conventional opposed designs in the market while also maintaining the power density, balancing, and performance benefits. Initially, a series of experiments were conducted on the proposed system for different speeds and throttle openings. Later, the combustion, performance, and quantified energy loss pathways were presented at Wide Open Throttle (WOT) conditions to demonstrate the performance benefits of the proposed system. Finally, a performance-oriented framework was developed for the proposed CHP system for future efforts.

Many parts of the world are facing the triple challenge of providing secure energy to fuel economic growth at an affordable cost while minimizing the impact of energy production on the environment. Island nations especially struggle to address this trilemma, as renewable resources are usually limited and fossil fuels imported. Traditionally such distributed power plants have relied on liquid fuels and multiple open cycle reciprocating engines to provide both redundancy and the ability to load follow across a broad load range to maximize efficiency. This approach has created high electricity prices and significant negative environmental impact, especially that attributed to CO 2 , NO x , and SO x . With increasing natural gas production, the availability of Liquefied Petroleum Gas (LPG) has grown, and costs have fallen, allowing the potential to switch from fuel oils to LPG to reduce environmental impacts. Energy costs and environmental impact can be further reduced by using high efficiency Gas Turbine Combined Cycle plants with dry low emissions combustion technology. However, a further hurdle facing many locations is lack of the fresh water required for combined cycle operations. LPG-fuelled Gas Turbine Combined Cycle using Organic Rankine Cycle (ORC) technology can address all aspects of this energy trilemma. This paper reviews the conceptual design of a proposed 100MW distributed power plant for an island location, based on multiple LPG-fuelled gas turbines to follow load demand, with an ORC bottoming cycle to maximize efficiency.

In this research, we utilize Southern California (SoCal) natural gas transmission pipelines and underground storage resources for transporting and storing hydrogen gas for a 100% renewable energy penetration. The goal is to determine to what extent natural gas infrastructure can be used to deliver and store hydrogen to meet SoCal electric demand for a 100% renewable energy portfolio. Hydrogen is produced from solar power generation using electrolysis next to the gas transmission pipelines whenever it is available in quantities greater than the electricity demand. It was found that using four main transmission pipelines owned by Southern California Gas company (SoCalGas) to transport hydrogen from the point of production to the four underground storage fields to store and later generate electricity through fuel cells can transport and store hydrogen sufficient to meet 40% of the SoCal electricity demand. That is, without any investment in additional transmission and distribution infrastructure, and without any investment in energy storage, the idea of building solar farms in the desert and using only the gas system for storage and transmission and distribution leads to a 40% increase in renewable electricity for the state.

Lean-premixed (LPM) gas turbines have been developed for stationary power generation in efforts to reduce emissions due to strict air quality standards. Lean-premixed operation is beneficial as it reduces combustor temperatures, thus decreasing NO x formation and unburned hydrocarbons. However, tradeoffs occur between system performance and turbine emissions. Efforts to minimize tradeoffs between stability and emissions include the addition of hydrogen to natural gas, a common fuel used in stationary gas turbines. The addition of hydrogen is promising for both increasing combustor stability and further reducing emissions because of its wide flammability limits allowing for lower temperature operation, and lack of carbon molecules. Other efforts to increase gas turbine stability include the usage of a non-lean pilot flame to assist in stabilizing the main flame. By varying fuel composition for both the main and piloted flows of a gas turbine combustor, the effect of hydrogen addition on performance and emissions can be systematically evaluated. In the present work, computational fluid dynamics (CFD) and chemical reactor networks (CRN) are created to evaluate stability (LBO) and emissions of a gas turbine combustor by utilizing fuel and flow rate conditions from former hydrogen and natural gas experimental results. With CFD and CRN analysis, the optimization of parameters between fuel composition and main/pilot flow splits can provide feedback for minimizing pollutants while increasing stability limits. The results from both the gas turbine model and former experimental results can guide future gas turbine operation and design.

The use of large-bore Otto gas engines is currently spreading widely considering the growing share of Power-To-Gas (P2G) solutions using renewable energies. P2G with a Combined Heat and Power (CHP) plant offers a promising way of utilizing chemical energy storage to provide buffering for volatile energy sources such as wind and solar power all over the world. Therefore, ambient conditions like air temperature, humidity and pressure can differ greatly between the location and time of engine operation, influencing its performance. Especially lean-burn Otto processes are sensitive to changes in ambient conditions. Besides, targeted use of humidity variation (e.g. through water injection in the charge air or combustion chamber) can help to reduce NO x emissions at the cost of a slightly lower efficiency in gas engines, being an alternative to selective catalytic reduction (SCR) exhaust gas aftertreatment. The ambient air condition boundaries have to be considered already in the early stages of combustion development, as they can also have a significant effect on generated measurement data in combustion research. To investigate the behavior, a test bench with a natural gas (CNG) powered single-cylinder research engine (piston displacement 4.77 1) at the Institute of Internal Combustion Engines (LVK) of the Technical University of Munich (TUM) was equipped with a sophisticated charge air conditioning system. This includes an air compressor and refrigeration dryer, followed by temperature and pressure control, as well as a controlled injection system for saturated steam and homogenizing containers, enabling the test bench to precisely emulate a widespread area of charge air parameters in terms of pressure, temperature and humidity. With this setup, different engine tests were conducted, monitoring and evaluating the engine’s emission and efficiency behavior regarding charge air humidity. In a first approach, the engine was operated maintaining a steady air-fuel equivalence ratio λ, fuel energy input (Q̇ fuel = const.) and center of combustion (MFB 50%) while the relative ambient humidity was varied in steps between 21% and 97% (at 22 °C and 1013.25 hPa). Results show a significant decrease in nitrogen oxides (NO x ) emissions (−39.5%) and a slight decrease in indicated efficiency (−1,9%) while hydrocarbon (THC) emissions increased by around 60%. The generated data shows the high significance of considering charge air conditioning already in the development stage at the engine test bench. The comparability of measurement data depends greatly on ambient air humidity. In a second approach, the engine was operated at a constant load and constant NO x emissions, while again varying the charge air humidity. This situation rather reflects an actual engine behavior at a CHP plant, where today often NO x –driven engine control is used, maintaining constant NO x emissions. The decrease in indicated efficiency was comparable to the prior measurements, while the THC emissions showed only a mild increase (5%). From the generated data it is, for instance, possible to derive operational strategies to compensate for changes in ambient conditions while maintaining emission regulations as well as high-efficiency output. Furthermore, the results suggest possibilities, but also challenges of utilizing artificial humidification (e.g. through water injection) considering the effects on THC emissions and efficiency. A possible shift of the knocking limit to earlier centers of combustion with higher humidity is to be investigated. The main goal is the further decrease of NO x emissions, increase of efficiency, while still maintaining hydrocarbon emissions.

Small modular reactors (SMRs) are small-scale reactor designs (< 300 MWe), generally planned for deployment as multi-module nuclear power plants. Due to their small size, SMR modules could be manufactured in a factory and deployed to a site via truck or rail for installation and fueling. SMRs are being evaluated for their ability to provide both power and steam, such that they could be a viable replacement for fossil fuels. SMRs have been considered for coupling to manufacturing processes in addition to being connected to the grid, allowing them to follow the net grid demand in a “load following” operational mode during times of high renewable generation. Alternately, SMRs could be used to replace cogeneration and combined-cycle processes at manufacturing plants which utilize natural gas and other fossil fuels. Idaho National Laboratory (INL) is studying the use of SMRs for large-scale manufacturing processes that require both electricity and steam. The current study examines the integration of a SMR with two mid-size pulp and paper mills in the southeastern United States. The study consists of three parts: steady-state analysis of the mill, elimination of fossil fuel use in the lime kilns, and economic analysis of the modified plant operations. A steady-state model of each mill is developed in Aspen HYSIS based on real data from the operation of each mill. The steady-state model is then modified to include the SMR while maintaining production steam quality and making as few changes to existing equipment as possible. This model gives an estimate of the minimum requirements for SMR output, as well as the change in generation by existing boilers and turbines. With an overall picture of the new plant operation and determining the number of SMR modules required, further changes are suggested to minimize or completely eliminate fossil fuel use from the plant. Apart from steam generation, the largest consumer of fossil fuels at the plant is typically the lime kilns. Conversion of the lime kilns from fossil fuel combustion to electric heating is the most feasible solution to eliminate fossil fuels. This study finds that electric lime kilns are economical when the plant has a surplus This study presents a feasible example of using an SMR as a substitute for fossil fuel cogeneration. If this approach were expanded across the manufacturing industry, it would have a significant impact on environmental emissions and air quality.

The University of California, Irvine (UCI) uses a 19 MW natural gas combined cycle (NGCC) to provide nearly all campus energy requirements. Meanwhile, the University of California system has committed to achieving carbon neutrality at all facilities by 2025. This has resulted in an influx of new energy efficiency and onsite solar generation, increasing the duration of NGCC part load operation. In addition, the shift towards carbon neutrality has resulted in the pursuit of renewable natural gas via anaerobic digestion to replace conventional fossil fuels. The combination of other sources of renewable generation and the shift towards more expensive fuels has created the need to boost NGCC part load performance. This work focuses on the methods used at UCI to explore the NGCC operating space in order to optimize part-load performance. In this work, a physical gas turbine and heat recovery steam generator model are developed and used with an exhaustive search optimization method to predict maximum part load plant efficiency. NGCC control elements considered in this work include gas turbine inlet guide vane modulation and changing combustor outlet temperature. This optimization was also used to explore replacing the current engine with a two-shaft or smaller gas turbine. Results indicate that there are some possible benefits with increased modulation of inlet guide vanes, but the largest efficiency gains are achieved when allowing the compressor to operate at variable speed. Shifting towards a smaller engine could also enable more consistent full power operation, but must be paired with additional resources in order to meet the campus demand.

Traditional carbon capture technology has been shown to effectively capture emissions, but at a cost of reducing power plant output. Molten carbonate fuel cell technology (MCFC) has the potential to be able to concentrate plant carbon emissions into a gas stream that is suitable for storage while boosting total plant power output. When considering this type of technology, the original purpose and function of the power plant must be considered. In particular, gas turbines (GT) based natural gas combined cycle (NGCC), which are capable of dynamic load following operation, are likely to need to maintain operational flexibility. This work explores the retrofit of an existing GT with MCFC technology for carbon capture when the plant is operated at part load. Physical models for major plant components are built and used to select optimal operating set points such that operating cost is minimized. Special attention is given to ensuring feasible operation across all engine components. The results show MCFC operational parameters that minimize change in fuel cell operating conditions when the gas turbine is operated at part load.

Renewable energy has a significant role to play in helping the world achieve the greenhouse gas emission reduction necessary to achieve the pathway to a 2°C increase in global temperature. Electricity generation from wind and solar resources can contribute immensely to the decarbonization of power generation, but these resources are intermittent. High penetration of intermittent renewable power generation can cause grid stability and control issues for network operators, with fast response fossil fuel power plant necessary to provide security of supply and maintain grid stability. Increasingly natural gas-fueled distributed power generation is being installed to provide the necessary grid support. However, hybrid power plants comprised of a fossil fuel power generating system, a renewable power generation system and energy storage can provide both the low CO 2 electricity required to meet environmental constraints, and the despatchability and stability required by grid operators. Integrated Solar Combined Cycle Power Plants (ISCCs), comprising a Concentrated Solar Power plant and a natural gas fired combined cycle plant, have the potential to simultaneously reduce fossil fuel consumption, provide secure, highly predictable electricity generation, and reduce the cost of integrating renewable energy into a power system. While a number of ISCCs have been built at a larger scale (above 150MW power output), the concept has rarely been adopted for smaller scale distributed power applications. In addition, the traditional ISCC concept uses a steam bottoming cycle, which consumes water, and often locations where distributed ISCC could be utilized suffer from a scarcity of fresh water. This paper evaluates whether replacing the steam bottoming cycle with an Organic Rankine Cycle (ORC) alternative can provide a simpler, lower cost distributed ISCC solution that can be utilized on smaller and island grid systems, or mini- and micro-grids, to provide an affordable, water-free, low carbon power generation system.

Over the past decade, several technical developments (such as hydraulic fracturing) have led to an exponential increase in discovering new domestic natural gas reserves. Raw natural gas composition can vary substantially from source to source. Typically, methane accounts for 75% to 95% of the total gas, with the rest of the gas containing ethane, propane, butane, other higher hydrocarbons, and impurities, with the most common including H 2 O, CO 2 , N 2 , and H 2 S. All natural gas requires some treatment, if only to remove H 2 O; however, the composition of natural gas delivered to the commercial pipeline grids is tightly controlled. Sub-quality natural gas reserves, which are defined as fields containing more than 2% CO 2 , 4% N 2 , or 4 ppm H 2 S, make up nearly half of the world’s natural gas volume. The development of sub-quality, remote, and unconventional fields (i.e. landfill gas) can present new challenges to gas separation and purification methods. Adsorbent technologies, such as the use of activated carbons, zeolites, or metal-organic frameworks (MOFs), may hold the key to more efficient and economically viable separation methods. This work proposes to prove the applicability of the multi-component potential theory of adsorption (MPTA) to a real world natural gas adsorbent system to properly characterize the adsorbent’s selectivity for an individual gas component using only the single component isotherms. Thus, the real-world gas separation/purification application of a specific adsorbent for a given gas stream can be obtained simply and effectively without the need for large experimental efforts or costly system modifications until after an initial computational screening of perspective materials has been completed. While the current research effort will use natural gas, which is the world’s largest industrial gas separations application, to validate the MPTA, the tools gained through this effort can be applied to other gas separation effort.

This paper attempts to quantify global development of coal- and natural gas-based power between 2003 and 2016 by analyzing the progression of individual coal and natural gas power units of 100 megawatts or greater as reported by S&P Global Platts. About 1,000 gigawatts (GW) of new coal capacity entered service worldwide in this period, nearly doubling the world coal power fleet. About 96% of this new capacity was built in 10 countries led by China and India. The momentum of global coal power development has slowed since 2014 with cancelled, deferred, or delayed capacity in 2016 more than quintupling that reported in 2013. This slowdown occurred mainly in China and India, where 426 GW of coal capacity were cancelled during 2015 and 2016, while only 26 GW was built. The vast majority of the new coal capacity built in Germany, Japan, and South Korea since 2003, and the majority in China since 2008, use supercritical or ultra-supercritical (USC) technologies. Subcritical technology still prevails among units constructed in developing countries, but USC units are being built in all the top 10 countries except the United States, where no new coal power plant is currently under construction.

Statistical analytics, as a data extraction and fault detection strategy, may incorporate segmentation techniques to overcome its underlying limitations and drawbacks. Merging both techniques shall provide a more robust monitoring structure to address the proper identification of normal and abnormal conditions, to improve the extraction of fundamental correlation among variables, and to improve the separation of both main variation and natural variation (noise) subspaces. This additional feature is key to limit the false alarm rate and to optimize the fault detection time when it is implemented on industrial applications. This paper presents an analysis to determine whether a segmentation approach, as a previous step of detection, enhances the fault detection strategies, specifically the principal component analysis performance. The data segmentation criteria assessed in this study includes two approaches: a) Sources (well) of the transmitted natural gas and b) Promigas’ natural gas pipeline division defined by the Energy and Gas Regulation Commission (CREG in Spanish). The performance assessment of segmentation criteria was carried out evaluating the false alarm rate and detection time when the natural gas transmission network presents faults of different magnitude. The results show that the implementation of a segmentation criteria provides an advantage in terms of the detection time, but it depends of the fault magnitude and the number of clusters. The detection time is improved by 25% in the case scenario I, when transition zones are considered. On the other hand, the detection time is slightly better with less than 10% in the case scenario II, where the segmentation is geographical.

The Kemper County Project has demonstrated Transport Integrated Gasification (TRIG™) at a 2-on-1 Integrated Gasification Combined-Cycle (IGCC) facility located in Kemper County, Mississippi. Kemper is the largest IGCC project in the world, the first to use lignite as fuel, the first to capture and sell CO 2 , and the first to produce multiple byproducts from initial startup. The facility features two Siemens SGT6-5000F gas turbines, each capable of operating on a high-hydrogen syngas produced in the Transport Gasifiers from locally mined lignite. Using high-hydrogen syngas requires unique modifications to the combustion turbine design. Flame-diffusion combustors, rather than dry low-NO X designs, prevent flashback caused by the high hydrogen content of the syngas. Also, ports added to the turbine compressor casing allow air to be extracted from the compressor and used elsewhere in the plant, supplying up to one half of the air required by the gasifier. The Kemper facility has achieved the integrated operation of both gasifiers, including the production of electricity from syngas by both combustion turbines. Turbine operation on the high hydrogen syngas was smooth both during normal operations and during transitions, with efficiencies meeting or exceeding expectations. This paper describes the Kemper plant design, focusing on the combustion turbine design unique to Kemper. The paper also discusses turbine design challenges specific to Kemper, provides an overview of the robust control scheme used on both syngas and natural gas co-firing operations, and provides preliminary operational and performance results, including inspection findings.

Today there is a growing concern about the ramifications of global warming resulting from the use of fossil fuels and the associated carbon dioxide emissions. Oxy-fuel combustion is a promising response to this issue, since the product of the combustion is a CO 2 rich flue gas, which requires no further separation from other emission gases and thus can be sequestrated, or utilized. Here we present an analysis of a novel technology for combining oxy-fuel combustion with utilization of the CO 2 rich flue gas for syntetic fuel production. The technology concept involves a new method of using concentrated solar energy for the dissociation of carbon dioxide (CO 2 ) to carbon monoxide (CO) and oxygen (O 2 ). Simultaneously, the same device can dissociate water (H 2 O) to hydrogen (H 2 ) and oxygen (O 2 ). The CO, or the mixture of CO and H 2 (called Syngas), can then be used as a gaseous fuel (e.g. in power plants), or converted to a liquid fuel (e.g. methanol), which is relatively easy to store and transport, and can be used in motor vehicles and electricity generation facilities. The oxygen produced in the process can be used in oxy-fuel combustion or other advanced combustion methods in power plants. In this study it is assumed that a typical sub-critical, 575 MW, coal firing power plant is converted to oxy-fuel combustion. The flue gases from that power plant are then used as raw material for fuel production. The aim of the study is to estimate the optimal conceptual design of a power generation plant, including liquid/gaseous fuel generation facility. In the present study we used a series of special models for simulating the heat balance, heat transfer, performance and emissions of an oxy-fuel converted utility boiler. We also employed cycle simulation software that facilitates the optimization of an electricity generation plant with CO 2 conversion to liquid fuel and usage of the fuel produced from CO 2 for additional electricity production. The simulation results show that the amount of fuel produced, additional power generated and power station self consumption may be changed over a wide range, depending on the size of the solar field, which provides the energy for the liquid fuel production. The paper includes an overview of some of the key technical considerations of the new concept of CO 2 conversion to fuel. Based on the obtained results it may be concluded that the methodology presented in this study is an attractive option for CO 2 emission reduction, which can be implemented in existing and/or new power generation units. The technology proposed in this paper is not indented as an alternative for replacing coal combustion with natural gas, however may be used effectively with oxy-fuel combustion of either coal or natural gas.

Toshiba has been developing a turbine and a combustor for a semi-closed recuperated Brayton cycle of supercritical carbon dioxide called the Allam cycle, which is capable of both sequestrating 100% of carbon dioxide generated by combustion and providing electricity with competitive efficiency as the advanced combined cycle. The 25 MWe class demonstration plant with natural gas for this innovative cycle is being constructed in the USA by NET Power LLC and its operation is expected to be in 2017. Toshiba is going to provide the main components of its turbine and combustor. This paper describes the specification of the turbine and the combustor and consideration necessary to realize them in the first of a kind design condition of 30MPa with a supercritical carbon dioxide as its working fluid. This paper also describes some of the validation tests to realize new technologies before this turbine and combustor are installed and operated in the demonstration plant.

The Claus reactors is widely used to recover elementary sulfur from hydrogen sulfide that is contained in fresh natural gas. It involves thermal oxidation of hydrogen sulfide and its reaction with sulfur dioxide to form sulfur and water vapor. To improve the efficiency of the process, we built two kinds of 3-dimensional Claus reactor models to explore the key factors that affect the combustion reactions. The two-channel Claus reactor consisted of an air channel and an acid gas channel (60% H 2 S, 33% CO 2 , 7%H 2 O) while the three-channel Claus reactor consisted of two air channels and an acid gas channel (60% H 2 S, 33% CO 2 , 7%H 2 O). The two-channel model was built according to the devices used in the factory while the three-channel model was improved by us from the two-channel model. In both the two models, air and acid gas turned into swirling flow in their channels respectively before their mixture. Then air and acid gas mixed and burned at the throat of the models. The most remarkable difference between the two kinds of Claus reactors was that the three-channel reactor had an additional inner air channel inside the acid gas channel that can be helpful to the mix of the acid gas and air. The second difference was that the two kinds of reactors had different deflectors to swirl in the flow fields. In this study, we compared the flow fields and concentration fields of the two kinds of Claus reactors by using a computational fluid dynamics (CFD) tool. The simulation results indicated that the swirling intensity and the mix intensity played an important role in the combustion reactions. The efficiency of sulfur recovery in Claus reactors increased with an increase of the swirling intensity or the mix intensity. The stronger the swirling intensity or the mix intensity was, the sooner the mixture of air and acid gas reached to the best stoichiometric ratio. The three-channel reactor had a better performance than that of the two-channel reactor due to the additional inner air channel which can strengthen the mix of the acid gas and air from the inside of the acid gas. Moreover, the helix deflectors in the three-channel reactor had a better swirling performance than that of the vane deflectors in the two-channel reactor. From the comparison of the two models, we can obtain a way to improve the process of elementary sulfur recovery in the industry, which can be helpful to reduce pollution emissions and improve economic performance.

Access to electricity is a key necessity in today’s World for economic growth and improvements in quality of life. However, the global challenge is addressing the so-called Energy Trilemma: how to provide secure, affordable electricity while minimizing the impact of power generation on the environment. The rapid growth in power generation from intermittent renewable sources, such as wind and photovoltaics, to address the environmental aspect has created additional challenges to meet the security of supply and affordable electricity aspects of this trilemma. Fossil fuels play a major role in supporting intermittent renewable power generation, rapidly providing the security of supply needed and ensuring grid stability. Globally diesel or other fuel oils are frequently used as the primary fuel or back-up fuel for fossil-fueled power generation plants at all scales, from a few kiloWatts to hundreds of MegaWatts, and helps provide millions of people with secure electricity supplies. But diesel is a high polluting fuel, emitting high levels of carbon dioxide (CO 2 ) per unit of fuel input compared to natural gas, as well as high levels of combustion contaminants that are potentially hazardous to the local environment and human health. Additionally, diesel can be a high cost fuel in many countries, with imports consuming significant portions of sometimes scarce foreign currency reserves. Most observers consider that natural gas is the ‘fuel of choice’ for fossil power generation due to its reduced CO 2 emissions compared to coal and diesel. However, access to gas supplies cannot be guaranteed even with the increased availability of Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG). Additionally where natural gas is available, operators may opt for an interruptible gas supply contract which offers a lower tariff than a firm gas supply contract, therefore there is a need for a back-up fuel to ensure continuous power supplies. While traditionally diesel or Heavy Fuel Oil (HFO) has been used as fuel where gas is not available or as a back-up fuel, propane offers a cleaner and potentially lower cost alternative. This paper compares the potential economic, operational and environmental benefits of using propane as a fuel for gas turbine-based power plants or cogeneration plants.

Emissions reduction requirements lead to modification of the firing system to control NOx emission reduction, and/or the post combustion treatment of the flue gas to remove NOx, SO2 & particulates. It has also leads to installation of new renewable energy production systems. All of these measures are very expensive both in installation and operation costs, while utilities are looking for low cost options with a minimum impact on unit performance and reliability. Firing of methanol and its blends with other liquid fuels, in comparison with other renewable sources, is one of the main alternatives for meeting this target. Methanol is a clean burning fuel that is made from non-petroleum energy sources such as natural gas, coal, biomass and carbon dioxide. Using CO2 for methanol production leads to reducing of greenhouse gas emissions so that methanol can actually be called as enviro fuel. The blending of methanol with light fuel oil is one of the quickest and cheapest means for both replacing costly petroleum energy consumed in the existing power generation fleet and reducing emissions that lead to air pollution such as nitric oxides, carbon monoxide, air toxics and PM. Hence, methanol is a good candidate as an alternative fuel for power generation, since it is liquid and has several physical and combustion properties similar to fuel oil. For this reason, this study is aimed to evaluate gas turbine performance and emissions characteristics for different blends of methanol and light fuel oil. The results obtained from simulation of different light fuel blends were compared to those of actual burning. In this study we experimented with methanol fractions (from 0 to 100 % by heat) at different GT loads and found that the methanol and light fuel oil blends enabled us to significantly reduce NOx emissions with increasing of the methanol fraction. SO2 emissions were also reduced according to the methanol heat fraction. The final blend ratio optimization should be based upon environmental requirements and fuel price. CO emissions are slightly higher than the required level. Based on performed tests, the main reason for CO formation is high excess air, especially at partial loads and as a result of low combustion temperature (this conclusion is right for any fuel and its blends). In order to reduce CO emissions, proper air /fuel control is necessary (IGV, IBH etc). This conclusion is very important for conceptual design of gas turbines in general and particularly for GT conversion to methanol firing. Firing of methanol and its blends had no impact on GT performance and provides safe operation. The computer simulations provide support for these experimental findings and conclusions. The results of the performed tests analysis indicate that methanol firing is a potentially promising low cost technology for emissions’ reduction and may be implemented in existing and new gas turbines.

The ability to bypass steam, around the steam turbine and directly into a steam surface condenser, has been a fundamental aspect of the design of base loaded power plants for many years. The increased dependence on natural gas, and the subsequent increase in the number of combined cycle plants, has provided additional challenges for the condenser designer, and also the plant operator, with respect to safely accommodating steam bypass. However, the steam bypass requirements for modern combined cycle power plants differ significantly from those of traditionally base loaded plants, like fossil and nuclear. Higher cycle frequencies for steam bypass, faster start-ups, as well as increases in bypass steam temperatures and pressures, have all impacted the design criteria for the condenser. Indeed, for modern combined cycle plants, the bypass steam conditions are often higher than normal operation, such that the bypass requirements can very well dictate the overall design of the condenser. This, in turn, has resulted in an increase in the reported instances of operational problems, tube failures, condenser damage and plant shutdowns due to steam bypass related issues. Recorded issues and reported failures experienced by combined cycle power plants during steam bypass, have been traced to causes such as transient conditions during commissioning, faster start-ups, the poor design and location of steam bypass headers internal to the condenser, over-heating due to curtain spray deficiencies, excessive tube vibration and tube failures. Many of these issues are based on an inherent lack of understanding of the impact of the rigors of steam bypass on condenser internals. Furthermore, operation of steam bypass outside of the generally accepted design parameters often compounds these problems. This paper consolidates the learning and advances in the design of turbine bypass systems for steam surface condensers from the past 20, or so, years. It includes current design guidelines, as well as safe operational limitations, and general considerations for minimizing potential damage when operating steam bypass on a modern combined cycle power plant. Included is a Case Study of how an existing fossil power plant that was repowered, along with the existing steam surface condenser that was modified to accept the bypass steam, experienced excessive erosion and damage during the past 10+ years of operation. The condenser was recently reviewed once again, and additional modifications were implemented to take advantage of current improvements in steam bypass design. This drastically reduced further erosion and improved the condenser availability, reliability and longevity; thereby improving the plant efficiency.

The U.S. electric utility industry continues to undergo dramatic and accelerating transformation. Reliability and resiliency are a key focus. A number of important issues including cyber and physical security challenges, aging infrastructure, and low natural gas prices continue to be of concern. Significant advances in technology, and prolonged regulatory uncertainty are also contributing factors. Electric utilities are now making substantial investment in renewable resources and other technologies needed for renewables integration. This means a reduction in investment in generation assets and an increase in the transmission and distribution grids. There is also increased investment in providing customers with solutions to lower their costs, reduce their carbon footprint and provide control over their energy management. The transformation ultimately demands significant increases in power plant generation operating capabilities and higher levels of equipment reliability while reducing O&M and capital budgets. Achieving higher levels of equipment reliability, with such tightening budget and resource constraints, requires a very disciplined approach to maintenance and an optimized mix of the following maintenance practices: • Preventative (time-based) • Predictive (condition-based) • Reactive (run-to-failure) • Proactive (combination of 1, 2 and 3 + root cause failure analysis) Preventive maintenance (PM) is planned maintenance actions taken to ensure equipment is capable of performing its required functions. PM tasks are generally time-based, depending on the availability of condition monitoring data through a predictive maintenance (PdM) program. Traditionally, PdM is largely performed by maintenance technicians in the field with handheld devices. Resource constraints usually mean that often weeks or even months elapsed between readings on the same piece of equipment. This approach has limitations with data volume, velocity, variety, and veracity. Significant recent advances in sensor and technology associated with the Industrial Internet of Things (IIoT) have enabled the transformation of critical power plant assets such as steam turbines, combustion turbines, generators, and large balance-of-plant equipment into smart, connected power plant assets. These enhanced assets, in conjunction with analysis and visualization software, provide a comprehensive on-line conditioning monitoring solution that enables both a reduction in time-based PM tasks and also automation of PdM tasks. This paper describes an approach by Duke Energy to apply smart, connected power plant assets to greatly enhance its fossil generation equipment reliability program and processes. It will outline the value that is currently being realized and will also examine additional opportunities.