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Gas Letdown Generator™ Cogen System (GLG Cogen System) Energy Recovery from Natural Gas Letdown Stations
Prepared by: Langson Energy, Inc. Jan 2013
Langson Energy’s Gas Letdown Generator™ or GLG™ is an economically viable solution to energy recovery applicable to natural gas pressure reduction stations and city-gates. Paired with a cogeneration system that inherently creates heat that can be utilized by the GLG to return gas at desired temperatures, the challenges previously encountered in exploiting the tremendous kinetic energy lost through traditional pressure reduction valves (PRVs) have been solved. This revolutionary GLG Cogen System for waste energy recovery from gas pressure reduction will dramatically improve the economics of these green energy opportunities. The Langson GLG Cogen System has significantly lower capital costs than other green energy alternatives. Langson Energy Inc. (LEI) has solved the challenges of expensive turbine solutions for generating clean power from wasted gas pressure by integrating LEI technology with off-the-shelf components that have a proven history of reliable, robust, low-maintenance performance. Traditional turbines (a.k.a. turbo-expanders) have been the accepted method for generating power from pressure for many years. . However, their high capital costs and limitations in handling fluctuations in flow rates and pressure have proven to be significant hurdles to their widespread adoption.
I. Introduction The U.S. natural gas pipeline network is a highly integrated transmission grid that delivers natural gas to and from nearly any location in the lower 48 States. It is comprised of more than 210 natural gas pipeline systems; 305,000 miles of interstate and intrastate transmission pipeline; more than 1,400 compressor stations that maintain pressure on the network and ensure continuous forward movement of supplies; more than 11,000 delivery points, 5,000 receipt points, and 1,400 interconnection points that provide for the transfer of natural gas throughout the United States.1 The pipeline grid efficiently and safely moves more than 20 trillion cubic feet (Tcf) of natural gas annually to residential, commercial and industrial consumers. Most other countries, even islands, throughout the world have various sizes of local distribution companies (LDCs) that distribute gas from their such sources as well-heads or Liquid Petroleum Gas (LPG) stations. Generally the gas pipeline transmission system operates at high pressures required to transport the gas over great distances. This pressure must be reduced to lower levels for distribution to many
White paper – GLG Cogen System Jan 2013
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different types of end users. Pressure letdown is accomplished in stages and at multiple locations throughout the system (e.g. 1000 psi to 600 psi, 600 psi to 250 psi, 250 psi to 100 psi, etc.) The high pressure is reduced through mechanical regulating devices known as pressure reducing valves (PRVs) or Joule-Thomson (JT) valves. These devices reduce the pressure of the gas to the desired levels but wastefully dissipate the kinetic energy contained in the gas mainly through friction. The expansion or throttling of most gases results in a Joule–Thomson effect of lowering the temperature of the gas. This is the same thermodynamic principle at work that causes a can of compressed air to feel cold as the air expands when it is released. The rate of drop in temperature is directly proportional to the rate of pressure reduction. Since the GLG Cogen System (GLG™) creates minimal friction compared to a pressure reduction valve, the temperature reduction is significantly greater with the GLG™. Often this resulting cold can be utilized for air-conditioning, quenching water, jacket cooling, cooling towers, freezing, chilling, etc. However, most distribution pipelines need to maintain fairly constant temperatures along the distribution pipeline and the gas may need to be heated before entering a gas distribution system.
II. Langson Energy’s Solution Langson Energy Inc. (LEI)has developed an exceptionally efficient and unique system by coupling its Gas Letdown Generator™ on the same skid with a gas cogeneration system to produce the GLG Cogen System. The GLG™ utilizes oil-free helical screw technology, which has been utilized in the compressor business for over 100 years. By investing years of research, experimentation and true entrepreneurial and inventive genius, Mr. Richard Langson, inventor, LEI founder & CEO, has developed a method for this proven, low cost, low maintenance technology to operate as an energy conversion engine. By adding a cogeneration system to the system, not only is more electricity generated, but the waste heat from the cogeneration system is used to pre-heat the gas going into the GLG™. Thus co-generation, tri-generation and even quad-generation can be achieved when the cold is utilized in addition to the waste heat and the electricity from two generators. Capital Costs – The installed capital cost of the GLG Cogen System is significantly less than other energy efficiency solutions. Langson modifies readily-available and proven off-the-shelf components. This holds the capital investment in a GLG Cogen System to a fraction of what would be required for a radial inflow turbine installation. Helical screw technology has a proven track record of literally millions of hours of operation and tens of thousands of installations worldwide. Also see cost advantages under “Pressure and Flow Rate Variations” below. Operating Costs – The operating costs of the GLG Cogen System are estimated to be significantly less than alternative environmentally friendly systems. The only routine maintenance is a bearing and seal replacement every 50,000 hours on the GLG™ & traditional maintenance on the Cogenerator. The GLG™ will run for countless hours, trouble-free, providing extremely low maintenance and operational costs and with significant advantages in durability. Turbines are traditionally very susceptible to contamination and hydrates due to their very high speeds. The GLG™ does not suffer from these limitations. It can directly handle contaminants that would severely damage turbines. White paper – GLG Cogen System Jan 2013
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808 E College Parkway, Suite 102, Carson City, NV 89706 – 775-885-0888 (F)775-885-0882 www.LangsonEnergy.com
Pressure and Flow Rate Variations – Power Generation is directly tied to pipeline pressure and flows which frequently vary from season to season and even hour to hour. The GLG Cogen System has the ability to handle fluctuations in temperature, flows and pressures much better than turbines. Because the GLG™ responds to fluctuations easily and with no adverse effects, a producer is no long tied to a massive turbine and installation budgets to support such an investment. The GLG Cogen System allows any installation to scale their investment to better match year round flows which results in lower costs. The following graph and table can be used to get an idea of how much power output one Gas Letdown Generator could produce based on typical inlet and outlet temperate, pressure, and flow rates. It is important to note that since our machines can be installed in parallel or in series, the potential for power output is only limited by the amount of waste energy that could be recovered. When the GLG is paired with a cogeneration system the TOTAL electric output of the GLG Cogen System is increased by 25% to over 100% depending on the site specific conditions. Site potential can be calculated with the submission of Langson Energy’s Project Evaluation form (on website).
White paper – GLG Cogen System Jan 2013
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808 E College Parkway, Suite 102, Carson City, NV 89706 – 775-885-0888 (F)775-885-0882 www.LangsonEnergy.com
Base-Load Green Power – Langson’s GLG Cogen System operates 24 hours a day, 7 days a week, generating low cost green power capable of fulfilling green energy mandates while increasing baseload generating capabilities. Distributed Power – Another key advantage of the GLG Cogen System is the fact that it is distributed generation. Distributed resources not only provide benefits in the form of more reliable power for industries that require uninterrupted service, they improve the efficiency of providing electric power as the transmission of electricity from a power plant to a typical end user wastes roughly 4.2 to 8.9 percent of the electricity. The use of on-site power equipment can conceivably provide consumers with affordable power at a higher level of quality. 3 TM
Blackstart, Stand Alone and Off Grid Capability – In the stand alone mode, the GLG Cogen System can be used to power motors and other equipment needing electricity of megawatt capacity. Redundancy Capability – Lower capital investment and GLG Cogen System’s modular and compact design allow for the ability to create parallel, expandable and redundant power generation capabilities on a distributed basis. On those sites with sufficient flows and pressures to warrant multiple units, multiple units could be deployed.
III. Turbines Turbines are well-known throughout the power generation industry. They are rotary engines that extract energy from a fluid flow, whether that is gas, steam or combustion (e.g. jet engines). They efficiently use the energy in the fluid and are widely utilized for power generation. However, turbines have economic challenges when used as an expander for converting waste pressure to power. Large turbine manufacturers that have tried to promote this market have identified a number of key hurdles to economic application of Steam Turbine turboexpanders to pipelines. A variety of site specific factors affect project economics, the most important of which are the high capital cost of the systems themselves, and the recoverable value of the electricity generated. Other key variables include the gas flow rate and pressure drop, which together determine the power generation potential, and the hourly, daily and seasonal variability in flow. 2
V. Summary Langson Energy’s GLG Cogen System solves the challenges of utilizing wasted pressure from gas pressure letdown stations. Countless opportunities to make carbon free, base load green power are now re-opened in the gas distribution industry. This new technology warrants a re-examination of the potential of those installations with a new paradigm, the Langson Energy GLG Cogen System.
White paper – GLG Cogen System Jan 2013
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808 E College Parkway, Suite 102, Carson City, NV 89706 – 775-885-0888 (F)775-885-0882 www.LangsonEnergy.com
References: 1
Energy Information Agency, About U.S. Natural Gas Pipelines, 2008, www.eia.doe.gov
2
Interstate Natural Gas Association of America (INGAA), 2008, Waste Energy Recovery Opportunities for Interstate Natural Gas Pipelines 3
Consortium on Energy Restructuring, Virginia Tech, 2007, www.dg.history.vt.edu/ch1/benefits.html
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808 E College Parkway, Suite 102, Carson City, NV 89706 – 775-885-0888 (F)775-885-0882 www.LangsonEnergy.com