Bartosz Hrycak

Hydrogen production from ethanol in nitrogen microwave plasma at atmospheric pressure

Abstract Hydrogen seems to be one of the most promising alternative energy sources. It is a renewable fuel as it could be produced from e.g. waste or bio-ethanol. Furthermore hydrogen is compatible with fuel cells and is environmentally clean. In contrast to conventional methods of hydrogen production such as water electrolysis or coal gasification we propose a method based on atmospheric pressure microwave plasma. In this paper we present results of the experimental investigations of hydrogen production from ethanol in the atmospheric pressure plasma generated in waveguide-supplied cylindrical type nozzleless microwave (2.45 GHz) plasma source (MPS). Nitrogen was used as a working gas. All experimental tests were performed with the nitrogen flow rate Q ranged from 1500 to 3900 NL h-1 and absorbed microwave power PA up to 5 kW. Ethanol was introduced into the plasma using the induction heating vaporizer. The process resulted in an ethanol conversion rate greater than 99%. The hydrogen production rate was up to 728 NL[H2] h-1 and the energy efficiency was 178 NL[H2] per kWh of absorbed microwave energy. Graphical Abstract

Liquid fuel reforming using microwave plasma at atmospheric pressure

Hydrogen is expected to be one of the most promising energy carriers. Due to the growing interest in hydrogen production technologies, in this paper we present the results of experimental investigations of thermal decomposition and dry reforming of two alcohols (ethanol and isopropanol) in the waveguide-supplied metal-cylinder-based nozzleless microwave (915 MHz) plasma source (MPS). The hydrogen production experiments were preceded by electrodynamics properties investigations of the used MPS and plasma spectroscopic diagnostics. All experimental tests were performed with the working gas (nitrogen or carbon dioxide) flow rate ranging from 1200 to 3900 normal litres per hour and an absorbed microwave power up to 5 kW. The alcohols were introduced into the plasma using an induction heating vaporizer. The ethanol thermal decomposition resulted in hydrogen selectivity up to 100%. The hydrogen production rate was up to 1150 NL(H2) h−1 and the energy yield was 267 NL(H2) kWh−1 of absorbed microwave energy. Due to intense soot production, the thermal decomposition process was not appropriate for isopropanol conversion. Considering the dry reforming process, using isopropanol was more efficient in hydrogen production than ethanol. The rate and energy yield of hydrogen production were up to 1116 NL(H2) h−1 and 223 NL(H2) kWh−1 of microwave energy used, respectively. However, the hydrogen selectivity was no greater than 37%. Selected results given by the experiment were compared with the results of numerical modeling.

Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate

In this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity-resonant type. The aim of research was determination of electron excitation temperature Texc gas temperature Tg and electron number density ne. All experimental tests were performed with a gas flow rate of 100 and 200 l/min and absorbed microwave power PA from 0.25 to 0.9 kW. The emission spectra at the range of 300 – 600 nm were recorded. Boltzmann plot method for argon 5p – 4s and 5d – 4p transition lines allowed to determine Texc at level of 7000 K. Gas temperature was determined by comparing the measured and simulated spectra using LIFBASE program and by analyzing intensities of two groups of unresolved rotational lines of the OH band. Gas temperature ranged 600 – 800 K. The electron number density was determined using the method based on the Stark broadening of hydrogen Hβ line. The measured ne rang ed 2 × 1015 − 3.5×1015 cm−3, depending on the absorbed microwave power. The described MPS works very stable with various working gases at high flow rates, that makes it an attractive tool for different gas processing.

Microwave plasma for hydrogen production from liquids

Abstract The hydrogen production by conversion of liquid compounds containing hydrogen was investigated experimentally. The waveguide-supplied metal cylinder-based microwave plasma source (MPS) operated at frequency of 915 MHz at atmospheric pressure was used. The decomposition of ethanol, isopropanol and kerosene was performed employing plasma dry reforming process. The liquid was introduced into the plasma in the form of vapour. The amount of vapour ranged from 0.4 to 2.4 kg/h. Carbon dioxide with the flow rate ranged from 1200 to 2700 NL/h was used as a working gas. The absorbed microwave power was up to 6 kW. The effect of absorbed microwave power, liquid composition, liquid flow rate and working gas fl ow rate was analysed. All these parameters have a clear influence on the hydrogen production efficiency, which was described with such parameters as the hydrogen production rate [NL(H2)/h] and the energy yield of hydrogen production [NL(H2)/kWh]. The best achieved experimental results showed that the hydrogen production rate was up to 1116 NL(H2)/h and the energy yield was 223 NL(H2) per kWh of absorbed microwave energy. The results were obtained in the case of isopropanol dry reforming. The presented catalyst-free microwave plasma method can be adapted for hydrogen production not only from ethanol, isopropanol and kerosene, but also from different other liquid compounds containing hydrogen, like gasoline, heavy oils and biofuels.

Hydrogen production by dry reforming of kerosene using microwave plasma

This paper presents results of study of dry reforming of kerosene using a microwave plasma. The plasma was generated in waveguide supplied metal-cylinder-based nozzleless microwave plasma source (MPS) operated at 915 MHz. The rotational temperature of heavy species (assumed to be close to gas temperature) was up to 5500 K (for plasma without kerosene). The hydrogen production rate was up to 470 NL[H2]/h and the energy efficiency was 89.5 NL[H2] per kWh of absorbed microwave. Streszczenie. Artykuł przedstawia wyniki badań suchego reformingu nafty w plazmie mikrofalowej (915 MHz). Temperatura rotacyjna cząstek ciężkich (przyjmowana jako zbliżona do temperatury gazu) wynosiła do 5500 K (dla plazmy bez dodatku nafty). Uzyskana wydajność produkcji wodoru wynosiła do 470 NL [H2]/h, natomiast efektywność energetyczna do 89,5 NL [H2] na kWh zaabsorbowanej energii mikrofal. (Produkcja wodoru na drodze suchego reformingu nafty w plazmie mikrofalowej).

Characterization of an Atmospheric-Pressure Argon Plasma Generated by 915 MHz Microwaves Using Optical Emission Spectroscopy

The paper presents the investigations of an atmospheric-pressure argon plasma generated at 915 MHz microwaves using the optical emission spectroscopy (OES). The 915 MHz microwave plasma was inducted and sustained in a waveguide-supplied coaxial-line-based nozzleless microwave plasma source. The aim of presented investigations was to estimate parameters of the generated plasma, that is, excitation temperature of electrons Texc, temperature of plasma gas Tg, and concentration of electrons ne. Assuming that excited levels of argon atoms are in local thermodynamic equilibrium, Boltzmann method allowed in determining the Texc temperature in the range of 8100–11000 K. The temperature of plasma gas Tg was estimated by comparing the simulated spectra of the OH radical to the measured one in LIFBASE program. The obtained Tg temperature ranged in 1200–2800 K. Using a method based on Stark broadening of the Hβ line, the concentration of electrons ne was determined in the range from 1.4 × 1015 to 1.7 × 1015 cm−3, depending on the power absorbed by the microwave plasma.

Optical emission spectroscopy of plasma in waveguide-supplied nozzleless microwave source

Summary form only given. Recently, microwave plasma sources (MPSs) operated at atmospheric pressure have been developed [1]. Such devices were used in spectroscopy, technological processes like surface treatment, carbon nanotubes synthesis and sterilization. They also found applications in the processing of various gases. Destruction of Freon HFC-134a [2] and production of hydrogen via methane conversion [3] in microwave atmospheric pressure plasmas were reported by us. Optical emission spectroscopy (OES) is a very useful, powerful and valuable tool in the study of plasma properties (densities of electrons and heavy species, gas temperature, etc), contributing significantly to the development of microwave plasma technology and its applications.

Decontamination of microorganisms by low-temperature atmospheric pressure microplasma

Summary form only given. Development of the plasma sources based on the microwave technique are of increasing interest from industrial point of view [1]. Recently, one of the promising application is biomedical engineering like sterilization, food preservation, cells treatment [2]. This specific area of application requires low temperature atmospheric pressure plasma. Due to this we designed, built and tested experimentally a small, portable and easy to use microwave microplasma source (MmPS) [3, 4]. It has structure of a coaxial line, formed by an inner conductor, made of a brass rod with a tungsten rod top, and outer conductor in the form of a brass cylinder. The MmPS is operated at standard microwave frequency of 2.45 GHz. The generated by MmPS plasma has the form of a microflame forming at the tip of the inner conductor.