Archives mensuelles : janvier 2014

Some Historical background about the ORC technology

Hello all,

I found an interesting page about the ORC technology from the KCORG, and particularly about history of the ORC technology : ORC machine existed before even W. M. Rankine himself

While William M. Rankine (Scotland) developed a theory of the steam engine in 1859, engines using alcohol or ether as working fluid were designed as early as 1825/1826 (Thomas Howard). However leak rate and market price of the working fluid did not allow a full development of the technology for economical reasons.

It is worth also to mention the Du Trembley initiative in 1850, with a cascading steam/ether engine for ships. Du Trembley, an engineer from Lyon in France, developed its solution for ships on the Rhône river, reducing by more than 2 the specific consumption of the engine ! Invention was called « procédé à « vapeur combinées » », allowing to reach a better expansion in 2 stages with 2 fluids :

  • first stage with steam at 6 bar
  • second stage with ether vapor at 2 bar (vaporized at 60°C and condensed at 20°C)

Du trembley 2

It is worth to note that multiple stages expansion with saturated steam was not technically possible, and available steam boiler were not designed with superheaters.

Du trembley

While it is said that production of such motors was interrupted in 1856 due to an explosion in Bahia of such ship (1),  but others authors (2)  mention that explosion happened for other reasons, and that the production and use of the technology kept being used for navigation the following decades.

 

References:

(1) Closed Power Cycles: Thermodynamic Fundamentals and Applications, by Costante Mario Invernizzi, page 119

(2) Vapeurs sur le Rhône, Jean-Marc Combe, Bernard Escudié, Jacques Payen, Presses Universitaires Lyon, 1991

note : Picturesare  from (2) Vapeurs sur le Rhône, Jean-Marc Combe, Bernard Escudié, Jacques Payen, Presses Universitaires Lyon, 1991.

Combining Geothermal Energy with CO2 sequestration

Today, i’d like to entertain you with recent studies with improvements of geothermal technologies.

As you know geothermal energy use the heat from Earth crust/core to provide energy (heat, electricity or even chill). Most common applications for generating electricity are steam power plant (flash or dry steam) and binary power plant. In both cases, water is use as a thermal media, heated by the rocks and then pumped to the surface to be used directly in steam turbine or go through a heat exchanger and heat/vaporize a second fluid (working fluid), in the case of binary power plants.

If finding temperature on the deep ground is not a big problem (generally between 600m for volcanic regions and up to 6000 m for new generation of European deep geothermal projects), the key problem is to find water in the reservoir, and a good permeability so that the reservoir is not quickly depleted. Some technologies in development, known as EGS (for Enhanced Geothermal System) consider injecting water in some wells and pump it in others (see the project of Soultz, in East of France, a pioneer but costly pilot plant using this technology).

Recently, some researchers have been looking into using transcritical CO2 as a thermal media, instead of water. Transcritical means that the CO2 works about its critical point : at high pressure and high temperature it is not a gas, nor a liquid, but something in between and physical properties of the fluid are different from the two previous states. Some of the properties of transcritical fluids can be interesting, like low viscosity leading to low pressure drops.

Co2_g_othermie_capture_stockage_technologies_propres

CO2 is interesting for several reasons : it is a non dangerous, natural and cheap fluid ; its is abundant, not patented and free of use ; it is transcritical at relatively low temperature (but still high pressure); we would like to reduce its concentration in the atmosphere, and it is very likely that we would have to store some into the ground, to reduce global warming.

Some researchers at Berkeley National Lab in California (USA), have proposed an interesting technological solutions, where transcritical CO2 is used as thermal fluid to recover the heat from the deep (3200 m), then pump it and expand it directly in a CO2 expansion turbine

Cycle4View of the system by Berkeley lab

While costs of drilling cannot be neglected (you may consider roughly 5 Meuros per well), the system offer the possibility to store some CO2 in the process in the dead volume of the reservoir.

In area where the earth crust is hot, but very no/low water (typically where EGS would be useful) use of CO2 could be interesting.

Lire la suite

New video for Enertime ORCHID solution for Waste Heat Recovery

Hey there !

I’d like to share a video where you could see what a 1MW ORC module for waste heat recovery looks like.

This plant has been started in november 2012. It is the first machine we built at Enertime, all design including the turbine has been done by Enertime and its technological partners.

Enjoy !

Comments are in french, i guess that subtitles in english are or would be available.