Energy conversion efficiency increases with the engine size,
and most engines perform better at optimum design rpm and load.
Utility levels out individual demand and gain on distributed units efficiency...

Quasiturbine in Public Utility

Efficiency Gains

Utilities do have at least 2 advantages over distributed power conversion equipments. They can level off the demand which allows to select equipments to produce the optimum efficiency; and second, they group the needs of several of their customers, and can this way increase the size of their equipments, which generally lead to direct efficiency and environmental benefits.

Their efficiency is specially striking when compare to the transportation problematic, where vehicle average efficiency from the well to the wheel barely reach 10% (gas engine top efficiency could momentarily reach 30% only when at high engine power). For the same barrel of petrol, utilities will make 5 times more mechanical energy available to their customers. Of course, their forms of energy suffer from a lack of mobility (...or rather capability of storage in vehicle).

Steam power is staging what may prove to be the biggest grass-root comeback in the history of the industrial revolution! From micro-horsepower to Giga-Watts, from microchips to motorcycles, and from wheel chairs to missions to mars, STEAM POWER IS BECOMING PROMINENT IN VIRTUALLY EVERY INDUSTRY IN EVERY COUNTRY OF THE WORLD. Steam Quasiturbine could not come at a better time. Since the Quasiturbine is a pure expansion engine (which the Wankel is not, neither most of other rotary engines), it is well suitable as steam engine. Since the Quasiturbine is an hydrostatic turbine (instead of aerodynamic), it is also well suited for co-generation project with saturated steam.

Steam Quasiturbine has great potential for utilities, specially with fossil fuel steam, cogeneration and geothermal low temperature heat and near saturated steam. On the other hand, the detonation Quasiturbine engine is a rare concept potentially able to mach the utility efficiency and environmental cleanness the distributed way.

Moderate Temperature

In energy conversion equipments, working temperature differential is synonym of efficiency, but could also mean more nitrogen oxide pollutants, and extra cleaning cost. For this reason, moderate to low temperature steam are getting more and more attention today. Unfortunately, conventional turbines require very specific high steam quality and flow to be efficient, which make them almost useless with moderate temperature steam, often near saturation.

This is where the Quasiturbine steam engine takes over, because it is not an aerodynamic machine, and its efficiency is optimum at all pressure, load and rpm. Furthermore large Quasiturbine of several Mega-Watts can be operated at the same very low rpm of the generator, suppressing the need of costly gearboxes.

Co-Generation

What is worthless for some may be valuable to others. This is the idea about co-generation where the temperature cascade can be match to several applications, like turbine, Quasiturbine, drying process and finally district heating... Everyone served on the same barrel of petrol! Large scale utility co-generation is most interesting, specially in urban and industrial areas.

Distributed small scale co-generation is more challenging and more naturally scaled to human living style. It is presented on a different page.

Geothermal

Passive geothermal uses the immense stable underground heat sink where heat can be stored or removed at convenient cost through heat pumps. The reverse Quasiturbine Stirling act as heat pump for this purpose. Active volcanic geothermal can generate high pressure water fit to drive an hydraulic Quasiturbine, or even produce steam fit for the steam Quasiturbine. Still better, geothermal heat could be upgraded economically by burning some fossil fuel, and then be converted more efficiently into mechanical work.

Nuclear Steam

Because the nuclear reactor core is sensitive to temperature difference, it is used to add heat to high pressure water at almost constant temperature. This is the best which can be done for now, but with the consequences that the steam is quite low in temperature compare to coal or fuel burning stations, and turbine conversion is not as efficient. The Quasiturbine is in fact more appropriate for such an intermediary steam temperature conversion, partly because the Quasiturbine can accept steam condensation without damage. The Quasiturbine is listed as a nuclear steam technology by the INIS © International Atomic Energy Agency.

Large Size QT Steam

What would be the size of a 4000 HP Quasiturbine? First order of magnitude scaling shows the potential of the low rpm Quasiturbine steam for large size unit.

 
Quasiturbine pneumatic-steam model QT75SC (Without carriage) 
Usable with intake sustained pressure as low as 20 to 50 psi!
The Quasiturbine steam engine does not make any vibration.

Approximated theoretical steam case with a 33 bars (500 psi) effective differential pressure at 1800 RPM without any gearbox. This simplified linear extrapolation does not guaranty that the steam flow will permit to reach 1800 RPM for the larger units. Preliminary sizing data for Quasiturbine are as follow:

Notice that in 4 strokes internal combustion mode, the Quasiturbine power is about 1/8 of the one indicated, increasing almost linearly to this maximum 1800 RPM. In practice, divide the torque and power by 2 to account for the form factor would provide more realistic results.

This shows also potential for other applications like in marine or locomotive propulsion.

Combined Cycle

Quasiturbine HCCQT? Very high efficiency gas turbine electrical power plants use a Combined Cycle Gas Turbine CCGT to reach efficiency of about 55%, because (1) it uses the heat from the gas combustion cycle to turn a turbine and (2) it uses the residual heat to generate steam for a steam turbine cycle. These are quite high tech sophisticated pieces of equipment with limited live span time and further, they are accompanied by high maintenance cost.

In the Quasiturbine power plant, there would be also two cycles. In the first cycle, a Quasiturbine would be used as an internal combustion engine to generate electric power. The sensible heat from the first cycle would then be run through a heat exchanger to generate steam in a boiler for the second cycle. Because of similar Quasiturbine's unique ability to run on combusted hydrogen and steam, in the second cycle, steam would provide motive force to another Quasiturbine's, thereby increasing overall fuel efficiency. Furthermore, the Quasiturbine center being empty, the internal combustion (IC) and Steam Quasiturbines can be one the same shaft, with a simple ratchet coupling, and the torque will be cumulative on one single electrical generator! The interesting point (from a capital cost standpoint) is that it does not require two different systems, as with the natural gas turbine and the steam turbine do with a CCGT. The Quasiturbines would function as both a gas turbine (first cycle) and as a steam turbine (second cycle).

Thus, in principle, one could have a Combined Cycle Quasiturbine CCQT. The fuel efficiency of the CCQT would probably be less than a true CCGT (55%) but more than the Quasiturbine alone (33%) which can run at higher internal gas temperature because of early adiabatic expansion mechanical conversion. This type of efficiency would actually be more than a fuel cell stack, which, despite some claims to higher efficiency, is only about 35% at most from raw fuel, and quite costly on lifetime maintenance. For small unit, the combustion cycle could be combined with the Quasiturbine-Stirling cycle, which with a spoon of water can also work as a closed circuit steam engine.

Rotary Pressure Regulator
Gas Pipeline Expander

Gas Pipeline Pressure Energy Recovery - Rotary Pressure Expander
What about an "energy recovery rotary pressure regulator" ? An interesting application of the pneumatic Quasiturbine is to recover the pipeline high pressure energy at local distribution stations. Instead of using a conventional pressure regulator (an energy dissipative device), a pneumatic Quasiturbine will rotate under the pressure differential and the flow will be controlled by the rpm, i.e. the torque applied on the Quasiturbine shaft. It does act as a dynamic active rotary valve. This way, the Quasiturbine can transform the pressure differential into useful mechanical work to run pump, compressor, ventilator, electricity generator or locally convert the energy in high grade heat (better than pre-heating the gas before that same "rotary expander", to avoid any residual condensation as done with conventional regulators). Substantial heat is now given to conventional expansion valve in pure lost, while heat given to the gas at the intake of a rotary expander is essentially all recovered in mechanical energy or electricity. Because conventional turbines can not be widely modulated in rpm and load, they are not suitable for gas flow and pressure control, while the Quasiturbine is essentially a closed valve at zero rpm, and has high efficiency at all torque and all flow rpm. With such a system, any heat added before the Quasiturbine expands the gas and increases the available volumetric flow with the result that this heat is converted in mechanical energy with a very high efficiency. All experimental demonstration has to be done only by gas experts and under all current rules and regulations. Ignoring gas expansion and considering only the gas pressure flow, a 36 inches diam. gas pipeline at 700 psi carry typically a pressure power in excess of 30 MW - 25 millions of pound-ft/sec - of zero pollution pure mechanical energy almost totally recoverable through Quasiturbines in the heart of cities and industrial parks. This is tens of giant windmills on kW-h basis!. A survey (M. Dehli, GWF Gas-Erdgas 137/4, p.196, 1996) showed that in Germany alone, the potential for utilizing this pressure in 1996 was 200-700 MW, and the gas consumption has increased since then... See the conceptual diagram and a pipeline technical paper.

Enhance efficiency of LNG liquefaction cycle. Adsorption Refrigeration
Engineering Thermal Physics. Conventional pressure regulators cause all the gas from the constant high pressure side to expand, and the gas pressure-kinetic energy at the needle is converted into undesirable heat, thereby reducing the amount of cold produced. The Quasiturbine rotary expander allows for individual chambers to expand at a variable reduced pressure during expansion, and therefore reduces the transformation of the gas' kinetic energy into destructive heat. Furthermore, the Quasiturbine mechanically recuperates the gas' differential pressure energy, which can be used to run more compressors and make more refrigeration... for double the energy efficiency gain! This offers a great enhancement to the thermodynamic cooling machine, especially in high power LNG - Liquid Natural Gas liquefaction stations. Of course, this efficiency enhancement is also available for more modest cooling systems and air conditioning equipment. With Quasiturbine rotary expander, the efficiency of a gaseous only (like dry air) system reaches almost the efficiency of a phase change liquid-gaseous system, and sophisticated phase change chemical products often environmentally unwelcome are not anymore needed.

Other Utility Uses

Steam purges energy recovery. Since the industrial wide-area networks vapor boiler cannot be modulated quickly in power, these boilers generally produce some "steam surplus" to satisfy the fluctuations of demand which can reach 5 to 10% of the total capacity. When the steam call does not require this supplement, it is generally purged without purpose. However, the use of one or several Quasiturbine steam at the point of purge would allow to recover a part of the energy and to produce by intermittency compressed air or electricity...

Steam pressure reduction station. Also, a Quasiturbine placed on a steam line can act like a volumetric governor according to the power extracted, and better still, it can also act like a station of reduction of steam pressure for the various stages of the industrial processes, while recovering the unused energy.

Pumping steam-water condensate. Quasiturbine used in turbo-pump mode is particularly well adapted to pump steam condensate from steam injection in one of the Quasiturbine turbo-pump circuits.

Hydraulic to Pneumatic Conversion

Water waves sweeping through a fix caisson pressurizes the confined air, then relaxes it. These pressure variations can be directed toward both a pressurized tank and a vacuum tank. This conversion from hydraulic to pneumatic allows to conveniently drive pneumatic Quasiturbine (almost in closed loop) between both reservoirs, avoiding dirty water flow or icing conditions into the energy system. A similar pneumatic conversion can be done from any water head dam by dropping the water in a closed tube, and so compressing the confined air, and later letting the water go while creating a vacuum (Essentially still a fix caisson which is alternatively flooded and drained to simulate a large wave effect). Active ports management when at high and low pressure water level (opening the loop when the air flow become negligible) can further improve the efficiency. Other systems using Venturi water draft tube (siphon type) can also produce high vacuum air flow. These can be a very attractive solution for energy independence in vicinity of small rivers, where all the energy system equipments can be located safely ashore.

Since a water head of 32 feet (10 m) correspond to 1 atmosphere pressure (14 psi), this conversion generally involve pressure in the range of 20 to 60 psi, a secure level where efficiency is fairly good through Quasiturbine.

Wind to Pneumatic Conversion

Windmill are not without environmental problem. The concept of a vertical airplane wing (no moving part, except for alignment) producing high pressure on one side and low pressure on the other side, can generate at ground level an important air draft which could drive a Quasiturbine. Such air draft amplifiers could be alternative in some systems.

More Technical

Why Quasiturbine steam and solar energy?

Quasiturbine - Comparative efficiency

Quasiturbine Rotary Expander

International Association for the Advancement of Steam Power

Quasiturbine listed at INIS © International Atomic Energy Agency

The Steam-Powered Quasiturbine in Direct-Drive Railway Locomotive Propulsion