Hydrogen Removal From Heating Oil of a Parabolic Trough Increases the Life of the Trough and its Components
A Method to Selectively Remove & Measure Hydrogen Gas from a Fluid Volume
Parabolic trough power plants use concentrated solar thermal energy to generate electricity by producing steam that drives a Rankine power cycle. Solar thermal energy is captured in a fluid medium which flows through receiver tubes. At high temperatures the vapor generates hydrogen gas which can leak into the annular volume of the heat collection element. The presence of low partial pressures of hydrogen gas in the annulus significantly decreases the thermal performance of the heat collection element and can lead to degradation of equipment. The following invention allows for the removal of this hydrogen.Description
The main component of this invention is a Proton Exchange Membrane (PEM), such as Nafion, which has deposited palladium metal as layers on opposite sides of the membrane. This forms a membrane-electrode assembly where each palladium layer functions as an electrode and hydrogen ions are ionic conductors. The hydrogen selective membrane (HSM) is positioned such that the first palladium electrode is in contact with the fluid volume and the second palladium electrode is in contact with ambient air. With this arrangement, hydrogen within the fluid volume will selectively transport as hydrogen ions from the first palladium electrode, across the Nafion membrane to the second palladium electrode. The corresponding electrons will conduct through an external circuit. At the second electrode, hydrogen ions and electrons combine with oxygen to form water which is transferred to the ambient air by desorption and diffusion.
The HSM has several useful functions. As mentioned, it serves as a selective membrane that exclusively transports hydrogen from one electrode to the other. It also functions as a selective hydrogen monitor which measures the transport rate of hydrogen across the membrane and the concentration of hydrogen at the fluid-electrode interface on the hydrogen-rich side of the HSM.
- Hydrogen Selective Membrane (HSM) is not permeable to molecular gases including hydrogen, oxygen, nitrogen, carbon dioxide, etc.
- HSM will prevent the transport of gases into or out of the annulus or head space.
- Its conduction of hydrogen ions will allow the transport of hydrogen exclusively through the membrane to ambient air.
- Hydrogen reacts with oxygen from air – giving the device infinite capacity (unlike prior “gettters” that quickly become saturated)
- Rates of hydrogen removal can be determined by measuring the current through the external circuit.
- Hydrogen concentration at the first electrode can be determined by measuring the open-circuit voltage across the first and second electrodes.
Parabolic trough power plantsPatents and Patent Applications
|Title and Abstract||
Systems and methods for selective hydrogen transport and measurement
Systems and methods for selectively removing hydrogen gas from a hydrogen-containing fluid volume are disclosed. An exemplary system includes a proton exchange membrane (PEM) selectively permeable to hydrogen by exclusively conducting hydrogen ions. The system also includes metal deposited as layers onto opposite sides or faces of the PEM to form a membrane-electrode assembly (MEA), each layer functioning as an electrode so that the MEA functions as an electrochemical cell in which the ionic conductors are hydrogen ions, and the MEA functioning as a hydrogen selective membrane (HSM) when located at the boundary between a hydrogen-containing fluid volume and a second fluid.
|National Renewable Energy Laboratory||10/29/2013
|Technology ID||Development Stage||Availability||Published||Last Updated|