Charlotte, NC, United States
Charlotte, NC, United States

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Vane L.M.,U.S. Environmental Protection Agency | Alvarez F.R.,U.S. Environmental Protection Agency | Rosenblum L.,CB and I | Govindaswamy S.,BioTech Unlimited Inc.
Journal of Chemical Technology and Biotechnology | Year: 2013

BACKGROUND: In Part1 of this work, a process integrating vapor stripping, vapor compression, and a vapor permeation membrane separation step, 'membrane assisted vapor stripping' (MAVS), was predicted to produce energy savings compared with traditional distillation systems for separating 1-butanol/water and acetone-butanol-ethanol/water (ABE/water) mixtures. Here, the separation performance and energy usage of a MAVS pilot system with such mixtures and an ABE fermentation broth were assessed. Results: The simple stripping process required 10.4MJ-fuel kg-1-butanol to achieve 85% butanol recovery from a 1.3wt% solution. Addition of the vapor compressor and membrane unit and return of the membrane permeate to the column raised 1-butanol content from 25wt% in the stripping vapor to 95wt% while cutting energy usage by 25%. Recovery of secondary fermentation products from the ABE broth were based on their relative vapor-liquid partitioning. All volatilized organic compounds were concentrated to roughly the same degree in the membrane step. Membrane permeance, selectivity, and overall MAVS energy usage were the same with the broth as with the ABE/water solution. Conclusion: Energy usage of the MAVS experimental unit corroborated process simulation predictions. Simulations of more advanced MAVS designs predict 74% energy savings compared with a distillation-decanter system. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Chaker M.,CB and I | Mee T.R.,Mee Industries, Inc.
Proceedings of the ASME Turbo Expo | Year: 2015

Ambient temperature strongly influences gas turbine performance with power output dropping between 0.5 to 0.9 % for every 1C of temperature rise. This is accompanied by a significant increase in the heat rate, resulting in increased operating costs. As an increase in power demand often coincides with high ambient temperatures, power augmentation during the hot part of the day is of value to gas turbine operators. This is true for both the utility industry, where peak-rate power payments often apply, and to the petrochemical and process industries, where throughput can be improved or held constant as ambient conditions change. Evaporative fogging and wet compression are relatively lowcost solutions for recovering reduced gas turbine output. This paper addresses the important design considerations for fogging and wet compression systems for different sized gas turbines with different duct configurations. These design considerations include the selection of appropriate ambient psychrometric design conditions, selection of appropriate fog nozzles and the optimization of fog nozzle manifold locations in the inlet ducts. For this research, Computational Fluid Dynamics (CFD) software is used to analyze the interaction between the atomized water droplets and the airflow within the confined geometry of inlet air ducts. The location of the nozzle manifolds is simulated in the inlet ducts for four different inlet duct configurations. Experimentally obtained spray data is used to simulated water atomization in the inlet ducts. The effect of the duct geometry is analyzed in term of fog-spray cooling efficiency based on both nozzle manifold location and droplet size distribution. Copyright © 2015 by ASME.

Card R.W.,CB and i
American Society of Mechanical Engineers, Power Division (Publication) POWER | Year: 2013

A hybrid wet-dry cooling system can be designed for a large combined-cycle power plant. A well-designed hybrid cooling system will provide reasonable net generation year-round, while using substantially less water than a conventional wet cooling tower. The optimum design for the hybrid system depends upon climate at the site, the price of power, and the price of water. These factors vary on a seasonal basis. Two hypothetical power plants are modeled, using state-of the-art steam turbines and hybrid cooling systems. The plants are designed for water-constrained sites incorporating typical weather data, power prices, and water prices. The principles for economic designs of hybrid cooling systems are demonstrated. Copyright © 2013 by ASME.

Stobart M.,CB and I
IGT International Liquefied Natural Gas Conference Proceedings | Year: 2013

The Mt Hayes LNG Peakshaving Facility, the newest facility of its kind in North America, presented several unique design and construction related challenges. The facility is located on Vancouver Island about ten kilometers Southwest of Nanaimo, BC. It is owned and operated by Fortis BC and is used both to support growing gas demand on Vancouver Island and to backstop gas supply to the British Columbia mainland. Construction of the facility began in April of 2008 with commissioning completed in April of 2011. The facility was engineered, constructed, and commissioned by CB&I. The Mt Hayes facility has a 1.5bcf single containment LNG storage tank, a 7.5mmscfd liquefaction system, and a 150mmscfd vaporization system. The facility is located about 280 meters above sea level and connects through the use of two 3.5 kilometer pipeline spurs to the main high pressure pipeline traversing Vancouver Island. The liquefaction system consists of a mixed refrigerant loop using a two stage centrifugal compressor. The LNG vaporization system for sendout of LNG from the tank to the pipeline uses shell and tube heat exchangers with remote firetube heaters utilizing a hot water-ethylene glycol heating medium. For sendout the LNG is pumped from tank pressure (1psig) to very high pipeline operating pressures (MAOP 2160psig) using two 15 stage high pressure extank submerged motor can pumps The most significant design challenges resulted from the unusually high pressure pipeline interface coupled with low summertime pipeline flow-by rates. Construction challenges resulted from the site location, which is in a high seismic zone on an island near the top of a solid rock mountain. The environment is also very wet. This paper explores the design-build challenges associated with the facility and discusses solutions employed to overcome these challenges.

Crowle A.P.,CB and i
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2011

Large energy developments are taking place near shore, in locations around the world, including LNG jetties, oil production in shallow water and renewable energy projects. Crane vessels of all sizes are required to install the component parts for these projects. This paper explains current techniques and the design requirements to carry out the lifting of large units required for shallow water installations. Recent developments have seen the introduction of new vessels for offshore wind farm installation and their features are discussed. Copyright © 2011 by ASME.

Crowle A.P.,CB and I
RINA, Royal Institution of Naval Architects - Marine Heavy Transport and Lift IV, Papers | Year: 2014

This paper investigates the marine design aspects of large offshore modules. Lifted modules up to 10,900 tonnes are considered. In addition, float-over modules up to 24,000 tonnes are included in the paper. The advantages and disadvantages of different load-out methods by trailer, skidding or lifting are discussed. Transportation on cargo barges and on self-propelled heavy transport vessels are compared. The paper covers the subjects of intact stability, damage stability, ballast distribution, barge bending, local strength, motions in waves and possible slam and fatigue during transport. The lifting of modules is restricted by available crane capacity. However, these operations are sensitive to weather criteria which has consequences for the scheduling. Maximum lift weights are presented for high volume living quarter modules and very compact process modules. The key to maximising the lift capacity is to minimise the lifting radius and ensure that the lift points are placed in the optimum position with respect to the package centre of gravity. The lift radius is minimised by ensuring that all major layout decisions incorporate the needs of platform installation. Float-over installation requirements are considered for fixed and floating structures. The requirements for ballasting, mooring and fenders are discussed. The accuracy of the overall topside weight estimate is also important in maximising the package lift weight. Consequently, allowances and contingencies must be reduced to the minimum practical values consistent with the level of definition of the component weights. © CB&I.

Crowle A.P.,CB and I
RINA, Royal Institution of Naval Architects - International Conference on Marine Heavy Transport and Lift III | Year: 2012

This paper describes the naval architecture and structural design of onshore and offshore modules on self propelled Heavy Transport Vessels. The scheduling of design, fabrication and shipping are discussed. The process of long distance transport of modules has been evolving since the 1970s, when it was used for an onshore project in the UK. This work continues today for large offshore modules being transported from the Far East to the North Sea and for large LNG modules transported to locations in various parts of the world. Heavy Marine Transport is a well accepted method to move large modules around the world. This type of transport is normally limited to getting from and going to sheltered locations, where module loading and discharge operations are safely carried out in very mild environment. However, there is also a demand for loading, at a fabrication yard, and discharge at offshore locations. As these operations are sensitive to environmental conditions, they have consequences for scheduling. Also, with increasing size and weight of offshore structures and the desire to deliver these objects directly to remote offshore location, larger Heavy Transport Vessels are required, which may need to operate in significant sea states during offshore lift off or floatover. ©2012: The Royal Institution of Naval Architects.

Sullivan B.K.,CB and I
AIChE Ethylene Producers Conference Proceedings | Year: 2015

Cracking heaters represent the largest individual investment made in an ethylene plant. The operation of the heaters greatly impacts the economic performance of the plant, so the incentive for maintaining cracking heaters in optimal operating and mechanical condition is significant. The occurrence of short run lenghts, carburized or bowed tubes, process control excursions and capacity limitations can be indicative of basic problems that need to be rectified to optimize cracking heater performance. There are a number of factors that can detract from the optimal performance of a cracking heater and the life of its mechanical components. This paper will provide examples of common problems that result in degradation of cracking heater performance and will introduce methodologies for practical troubleshooting of those performance deficiencies. Some of the troubleshooting tips that will be addressed are: • Estimation of heat flux distribution by measurement of tube metal temperatures to assess distribution of heat release and combustion air • Identification of burner performance issues due to damage, fouling, pressure imbalances, tip misalignment/orientation and air register setting using visual inspections and firebox combustion surveys • Confirming hydrocarbon/stream and fuel flow measurements using venturi data and burner curves • Inspection of coil support system condition and evaluation of coil maintenance procedures to ensure coil stresses are minimized • Analysis of start up, shutdown and decoking procedures to identify manual operations that can shorten furnace run length and tube life • Visual inspection of firebox and convection casing for indications of refractory damage and intrusion of tramp air • Detection and mitigation of convection section fouling/damage (process and flue gas side) • Corroboration of cracking conditions via feed and effluent analysis • Evaluation and rectification of process control performance deficiencies.

Yan Y.,CB and I
American Society of Mechanical Engineers, Power Division (Publication) POWER | Year: 2014

Fuel gas for many Combined Cycle Power Plants is supplied directly by the gas provider's regulator station in locations where the gas pipeline pressure is sufficient without further compression. Other locations require one or more onsite compressors to boost the fuel gas pressure. A rising concern is the fuel gas system transient response immediately after a significant reduction in the plant fuel gas consumption. Transient analysis models have been developed for typical fuel gas systems of combined cycle plants to ensure that the system is configured to respond appropriately to unplanned disturbances in fuel gas flow such as when a gas turbine trip occurs. Pressure control (regulator) and booster compressor control loop tuning parameters based on quantitative transient model results could be applied to set up targets for use in specifying and commissioning the fuel gas system. Case studies are presented for typical large combined cycle plants with two gas turbines taking fuel from a common plant header. This is done for designs without or with fuel gas booster compressors. Copyright © 2014 by ASME.

Bhattacharya A.,CB and I | Bapat S.M.,CB and I
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2014

Bends are an integral part of a piping system. Because of the ability to ovalize and warp they offer more flexibility when compared to straight pipes. Piping Code ASME B31.3 [1] provides flexibility factors and stress intensification factors for the pipe bends. Like any other piping component, one of the failure mechanisms of a pipe bend is gross plastic deformation. In this paper, plastic collapse load of pipe bends have been analyzed for various D/t ratios (Where D is pipe outside diameter and t is pipe wall thickness) for internal pressure and in-plane bending moment, internal pressure and out-of-plane bending moment and internal pressure and a combination of in and out-of-plane bending moments under varying ratios. Any real life component will have imperfections and the sensitivity of the models have been investigated by incorporating imperfections as scaled eigenvectors of linear bifurcation buckling analyses. The sensitivity of the models to varying parameters of Riks analysis (an arc length based method) and use of dynamic stabilization using viscous damping forces have also been investigated. Importance of defining plastic collapse load has also been discussed. FE code ABAQUS version 6.9EF-1 has been used for the analyses. Copyright © 2014 by ASME.

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