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Heat Recovery Steam Generators
www.HeatRecoverySteamGenerators.com

What are Heat Recovery Steam Generators?

Heat Recovery Steam Generators, or HRSGs, are boilers that capture and recovers the exhaust of a prime mover such as a combustion turbine, natural gas or diesel engine to create steam.

Stated another way, HRSGs are used to recover energy from the hot exhaust gases in power generation. It is a bank of tubes that is mounted in the exhaust stack. Exhaust gases as much as 800 °F to 1200 °F heat these tubes. Water is pumped and circulated through the tubes and can be held under high pressure to temperatures of 370°F or higher which can be boiled to produce steam.

Furthermore, the HRSG separates the caustic compounds in the flue gases from the occupants and equipment that use the waste heat. HRSG's are found in may combined cycle power plants.

What is a Heat Recovery Boiler?

A heat recovery boiler make it possible to produce steam, hot water or hot thermal oil from the combustion gas or exhaust stacks from diesel engines, gas turbines (cogeneration), industrial boilers, industrial furnaces or incinerators.

What is a "Waste Heat Boiler"?

A waste heat boiler is a special type of boiler that generates steam by removing the heat from a process that would have otherwise been wasted.

Waste heat boilers are therefore able to provide significant reductions in fuel and energy expenses, as well as reduce greenhouse gas emissions.

What is a "Waste Heat Recovery Boiler"?

A waste heat recovery boiler is, essentially, a boiler without any energy input. Waste heat recovery boilers are usually placed on top of a heat source or stack. Inside the waste heat recovery boiler is a series of tubes that has water inside, that is continuously circulated. The "wasted heat" is recovered on the hot side, and transferred to the water inside the tubes of the waste heat recovery boiler, and then steam is generated to power a steam turbine generator, which then generates power.

For more information on waste heat recovery, please see: www.WasteHeatRecovery.com

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What is the Organic Rankine Cycle?

A Rankine cycle is a closed circuit steam cycle. (see Rankine Cycle). An Organic Rankine Cycle uses a heated chemical instead of steam as found in the Rankine Cycle. Chemicals used in the Organic Rankine Cycle include freon, butane, propane, ammonia, and the new environmentally-friendly" refrigerants. 


Why use a chemical refrigerant? 

A refrigerant boils at a temperature below the temperature of frozen ice. Solar heat, for example, of only 150 degrees Fahrenheit from a typical rooftop solar hot water heater, will furiously boil a refrigerant. The resulting high-pressure refrigerant vapor is then piped to an organic Rankine cycle engine. 


Why is it called "organic"? 

"Organic" is a term used in chemistry to describe a class of chemicals that includes Freon and most of the other common refrigerants. 

What is the Rankine Cycle?

The Rankine Cycle is a thermodynamic cycle used to generate electricity in many power stations, and is the real-world approach to the Carnot Cycle. Superheated steam is generated in a boiler, and then expanded in a steam turbine. The steam turbine drives a generator, to convert the work into electricity. The remaining steam is then condensed and recycled as feed-water to the boiler. A disadvantage of using the water-steam mixture is that superheated steam has to be used, otherwise the moisture content after expansion might be too high, which would erode the turbine blades.

What is Waste Heat Recovery?

Many processes, especially in industrial applications, produce large amounts of excess heat – i.e., heat beyond what can be efficiently used in the process.  Waste Heat Recovery methods attempt to extract some of the energy as work that otherwise would be wasted.  

Typical methods of recovering heat in industrial applications include direct heat recovery to the process itself, recuperators, regenerators, and waste heat boilers.  In many applications – especially those with low-temperature waste heat streams, such as automotive applications – the economic benefits of waste heat recovery do not justify the cost of the recovery systems.  Innovative, affordable methods that are highly efficient, applicable to low-temperature streams, and/or suitable for use with corrosive or “dirty” wastes could expand the number of viable applications of waste heat recovery, as well as improve the performance of existing applications.  Our focus is on the development of innovative Waste Heat Recovery processes and techniques that are (1) more efficient than conventional methods, yet still cost-effective; and (2) applicable to waste streams from which heat cannot be recovered easily with conventional methods.

Turning to cooling, air conditioning systems consume approximately 10% of the energy used in U.S. buildings and are key contributors to peak demand.  Consequently, improving the energy efficiency of air conditioning systems would substantially reduce overall energy consumption and enhance grid reliability.  For example, compressors require cooling to dissipate the heat produced during compression and could benefit from improved surface heat transfer – innovative designs could increase the available heat-transfer area or materials enhancement could increase the heat flux between the hot and cool sides of a heat exchanger.  Similarly, a reduction in the requirement for condenser cooling could provide significant energy savings if more-efficient, cost-effective technologies were developed.  

This is where we believe waste heat recovery integrated with our Solar Trigeneration energy systems represents a unique opportunity for commercial and industrial clients. 

Industrial Waste Heat Recovery

Waste Heat Recovery from exit gases can significantly increase the energy efficiency of industrial processes.  Energy can be recovered from flue and stack gases, vent gases, and combustion gases at a variety of temperatures at large-scale industrial plants (chemical plants, petroleum refineries, biorefineries, pulp and paper mills, etc.).

How we make and distribute electricity is changing! 

The electric power generation, transmission and distribution system (the electric "grid") is changing and evolving from the electric grid of the 19th and 20th centuries, which was inefficient, highly-polluting, very expensive and “dumb.”  

The "old" way of generating and distributing energy resembles this slide:

The carbon clock tracks total carbon dioxide emissions in metric tons since 1750.

Since 1750, humans have emitted over 5 trillion pounds of carbon dioxide into the atmosphere. Roughly half of this has ended up in the oceans where it is beginning to damage the coral reefs. The other half is still in the atmosphere and causing global warming. Each pound of CO2 takes up as much space as a 500 pound person.

The formula (which should be good for a year or two) is:
C(t) = 2.58 ×1012 + 1240×t, where t is seconds since the start of 2007.

C is tonnes (metric tons) of carbon dioxide emissions.
2205 x C gives pounds of carbon dioxide emissions.

That comes to over 43 billion tons/year or over 86 trillion pounds/year.

Carbon dioxide (2) = 1 carbon atom with 2 oxygen atoms.
Carbon has relative weight 12 and Oxygen 16.
So it takes only 12 pounds of carbon to make 12+16+16 = 44 pounds of CO2. 

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Greenhouse Gas Emissions Linked to 
the Loss of Polar Bears

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We support the Renewable Energy Institute by donating a portion of our profits to the Renewable Energy Institute in their efforts to reduce fossil fuel use through renewable energy and their goals to end pollution from Carbon Dioxide Emissions and Greenhouse Gas Emissions. 

The Renewable Energy Institute is "Changing The Way The World Makes and Uses Energy by Providing Research & Development, Funding and Resources That Create Pollution Free Power, Carbon Free Energy & Renewable Energy Technologies."

Heat Recovery Steam Generators
www.HeatRecoverySteamGenerators.com

info@HeatRecoverySteamGenerators.com

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