Thermal Decomposition Of Natural Gas Research Articles

ПРИМЕНЕНИЕ ПРОЦЕССА КАРНОЛА ДЛЯ ПРОИЗВОДСТВА МЕТАНОЛА И СНИЖЕНИЯ ВЫБРОСОВ УГЛЕКИСЛОГО ГАЗА

The Carnol system is the production of methanol from carbon dioxide (obtained from coal-fired power plants) and natural gas, and the use of the resulting methanol as an alternative fuel. The Carnol process produces hydrogen by thermal decomposition of natural gas, which then interacts with the CO2 extracted from the flue emissions of power plants. The resulting carbon can be stored or used as a raw material. The paper provides an estimated characteristic of the reduction of CO2 emissions of the Carnol process and system, and compares it with other traditional methanol production processes, including the use of biomass of industrial raw materials and vehicles powered by methanol fuel cells. CO2 emissions from a Carnol system that uses methanol as an alternative fuel can be reduced by 56 % compared to a conventional coal-fired power plant system. In the case of the use of methanol as fuel for motor vehicles, carbon dioxide emissions.

An Overview of Economic Analysis and Environmental Impacts of Natural Gas Conversion Technologies

This study presents an overview of the economic analysis and environmental impact of natural gas conversion technologies. Published articles related to economic analysis and environmental impact of natural gas conversion technologies were reviewed and discussed. The economic analysis revealed that the capital and the operating expenditure of each of the conversion process is strongly dependent on the sophistication of the technical designs. The emerging technologies are yet to be economically viable compared to the well-established steam reforming process. However, appropriate design modifications could significantly reduce the operating expenditure and enhance the economic feasibility of the process. The environmental analysis revealed that emerging technologies such as carbon dioxide (CO2) reforming and the thermal decomposition of natural gas offer advantages of lower CO2 emissions and total environmental impact compared to the well-established steam reforming process. Appropriate design modifications such as steam reforming with carbon capture, storage and utilization, the use of an optimized catalyst in thermal decomposition, and the use of solar concentrators for heating instead of fossil fuel were found to significantly reduced the CO2 emissions of the processes. There was a dearth of literature on the economic analysis and environmental impact of photocatalytic and biochemical conversion processes, which calls for increased research attention that could facilitate a comparative analysis with the thermochemical processes.

Generalized Redox-Responsive Assembly of Carbon-Sheathed Metallic and Semiconducting Nanowire Heterostructures.

One-dimensional metallic/semiconducting materials have demonstrated as building blocks for various potential applications. Here, we report on a unique synthesis technique for redox-responsive assembled carbon-sheathed metal/semiconducting nanowire heterostructures that does not require a metal catalyst. In our approach, germanium nanowires are grown by the reduction of germanium oxide particles and subsequent self-catalytic growth during the thermal decomposition of natural gas, and simultaneously, carbon sheath layers are uniformly coated on the nanowire surface. This process is a simple, reproducible, size-controllable, and cost-effective process whereby most metal oxides can be transformed into metallic/semiconducting nanowires. Furthermore, the germanium nanowires exhibit stable chemical/thermal stability and outstanding electrochemical performance including a capacity retention of ∼96% after 1200 cycles at the 0.5-1C rate as lithium-ion battery anode.

Effect of structural promoters on the catalytic performance of cobalt-based catalysts during natural gas decomposition to hydrogen and carbon nanotubes

ABSTRACTCatalytic thermal decomposition of natural gas to CO/CO2-free hydrogen production was studied over cobalt catalysts supported on Al2O3, MgO, and SiO2. The physico-chemical properties of the fresh catalysts were investigated by X-ray diffraction (XRD), temperature-programmed reduction (TPR), and surface area. In addition, the morphological structure of as-deposited carbon over the spent catalysts was characterized by transmission electron microscope (TEM), Raman spectroscopy, thermogravimetric analysis, and XRD. The obtained results proved that the catalytic activity and longevity of the cobalt-based catalysts strongly depended on the nature of the applied support. Among the catalysts tested, the Co/Al2O3 catalyst exhibited the highest activity and stability due to the higher dispersion and stabilization of cobalt particles because of formation of CoAl2O3 spinel phase. The lower activity of Co/SiO2 catalyst is mainly attributed to the aggregation of cobalt metal particles because of weak metal–support interaction. It was observed that both type and morphological structure of deposited carbon were strictly depended on the nature of the support. TEM images revealed that multi-walled carbon nanotubes were produced over Al2O3- and MgO-supported catalysts, whereas both carbon nanofibers and amorphous carbon were formed over the Co/SiO2 catalyst.

The Effect of H<sub>2</sub>S on Hydrogen and Carbon Black Production from Sour Natural Gas

Hydrogen and carbon black production via thermal decomposition of natural gas have been achieved using a carbon black furnace. Direct heat transfer from inert hot gases (argon) introduced into sour gas. The carbon black furnace is a small-scale axial flow reactor. There are 3 main chemical reactions through which carbon black is produced. Finally results indicate that the most influencing factor over these chemical reactions and CH4 and H2S conversions is reactor temperature.

Response to the comments made by Khalid M. Saqr on our paper titled “CFD analysis on the influence of helical carving in a vortex flow solar reactor”, Int. J. Hydrogen Energ. 2010: 35, 6248–6260.

In our paper titled “CFD analysis on the influence of helical carving in a vortex flow solar reactor”, we have presented a 3D CFD analysis of a turbulent and reactive flow for directly irradiated solar thermochemical reactor to characterize the influence of flow behavior on the heat transfer and solar cracking process. The heat transfer by radiation from carbon particles is considered by providing global absorption and scattering coefficients in the computational domain obtained from Mie code. The flow field is based on RNG k-3 model derived using renormalization group theory. We have validated our numerical procedure by comparing the outlet temperature and cavity temperaturemeasurements of Hirsch and Steinfeld (Solar hydrogen production by thermal decomposition of natural gas using a vortex-flow reactor. Int J Hydrogen Energy 2004; 29:47-55) for Run 1 Configuration 1. As it is seen in our paper, our numerical simulations predict the mixture (gas-particle) flowoutlet and cavitywall temperatures as 1240K and 1751.3K,which deviates from the experimentally

Co-production of hydrogen and carbon black from solar thermal methane splitting in a tubular reactor prototype

This study addresses the solar thermal decomposition of natural gas for the co-production of hydrogen and carbon black (CB) as a high-value nano-material with the bonus of zero CO 2 emission. The work focused on the development of a medium-scale solar reactor (10 kW) based on the indirect heating concept. The solar reactor is composed of a cubic cavity receiver (20 cm-side), which absorbs concentrated solar irradiation through a quartz window by a 9 cm-diameter aperture. The reacting gas flows inside four graphite tubular reaction zones that are settled vertically inside the cavity. Experimental results in the temperature range 1740–2070 K are presented: acetylene (C 2H 2) was the most important by-product with a mole fraction of up to about 7%, depending on the gas residence time. C 2H 2 content in the off-gas affects drastically the carbon yield of the process. The effects of temperature and residence time are analyzed. A preliminary process study concerning a 55 MW solar chemical plant is proposed on the basis of a process flow sheet. Results show that 1.7 t/h of hydrogen and 5 t/h of CB could be produced with an hydrogen cost competitive to conventional steam methane reforming.

Hydrogen production from solar thermal dissociation of natural gas: development of a 10 kW solar chemical reactor prototype

This study addresses the solar thermal decomposition of natural gas for the co-production of hydrogen, as well as Carbon Black as a high-value nano-material, with the bonus of zero CO 2 emissions. The work focused on the development of a medium-scale solar reactor (10 kW) based on the concept of indirect heating. The solar reactor is composed of a cubic cavity receiver (20 cm side), which absorbs concentrated solar irradiation through a quartz window via a 9 cm-diameter aperture. The reacting gas flows inside four graphite tubular reaction zones that are settled vertically inside the cavity. Experimental results were as follows: methane conversion and hydrogen yield of up to 98% and 90%, respectively, were achieved at 1770 K, and acetylene was the most important by-product, with a mole fraction up to about 5%. The effect of the methane mole fraction in the feed gas, the residence time and the temperature on the reaction extent was analyzed. In addition to the experimental section, thermal simulations were carried out. They showed a homogeneous temperature distribution inside the cavity receiver of the reactor and permit to draw up a thermal balance.

04/00867 Solar hydrogen production by thermal decomposition of natural gas using a vortex-flow reactor: Hirsch, D. and Steinfeld, A. International Journal of Hydrogen Energy, 2004, 29, (1), 47–55

04/00867 Solar hydrogen production by thermal decomposition of natural gas using a vortex-flow reactor: Hirsch, D. and Steinfeld, A. International Journal of Hydrogen Energy, 2004, 29, (1), 47–55

Using a Concentrating Solar Reactor to Produce Hydrogen and Carbon Black via Thermal Decomposition of Natural Gas: Feasibility and Economics

Producing hydrogen in a cost-effective manner while minimizing environmental impacts is a big challenge. Hydrogen can be generated with carbon as a by-product from thermal decomposition of natural gas. A system using a solar reactor to produce hydrogen on-site for fueling stations was examined for its technical and economic feasibility. Integrated energy and material balance calculations were made to determine the amount of hydrogen that could be produced from a given reactor size and heliostat field area. Hourly solar data were applied to the model to properly estimate real storage requirements. This paper gives the results of the study including the greenhouse gas emissions and energy balance.

Dynamics of soot formation by turbulent combustion and thermal decomposition of natural gas

This study investigates the formation process of soot particles in turbulent flows within fuel-rich natural gas flames. Research on carbon formation from relatively simple hydrocarbons under real process conditions and harsh environments allows new insights into the general understanding of soot formation. Experimental work was undertaken on a small-scale gas furnace based on the design of a modern oil-fired carbon black furnace. The combustion system investigated is fired by a nonpremixed, swirl stabilized, confined methane-air flame. The study comprises establishing conditions under which the production of soot particles takes place, progressing toward quantified analysis. A large number of process parameters have been investigated, and the relative role of incomplete combustion and thermal decomposition in the process of carbon particulate formation has been illustrated. Maximum solid carbon formation was realized at maximum air temperature and maximum furnace temperature. Experimental investigations, using carbon particle concentration measurements coupled with on-line gas analysis showed that slightly fuel rich conditions are governed by incomplete combustion only, whereas richer combustion systems are governed by thermal decomposition processes. Both processes are found to be strongly temperature dependent, whereby an increase in temperature reduces particle production in the former process, but enhances it in the latter. A 3-D simulation of the simultaneous processes of incomplete fuel combustion and fuel decomposition in turbulent combustion systems, using a novel integration of fluid mechanics, chemical kinetics, and a standard soot model, facilitates discrimination between the two main sources of carbonaceous particulate matter, and indicates reasonable agreement with experimental trends.

Natural gas pyrolysis in the regenerative gas heaterPart i: Natural gas thermal decomposition at a hot matrix in a regenerative gas heater

This paper presents the results of an experimental investigation of natural gas pyrolysis at a hot matrix in a high temperature regenerative gas heater. It was demonstrated that formation of pyrocarbon during thermal decomposition of natural gas significantly influences upon the process efficiency. Burn out of the carbon deposits from the matrix during the matrix heating up stage produces components harmful to the environment. To make the pyrolysis process effective and environmentally benign it is necessary to provide special measures to exclude the possibility of pyrocarbon formation during the pyrolysis.

Production of hydrogen and methanol from natural gas with reduced CO 2 emission

The thermal decomposition of natural gas forms the basis for the production of hydrogen with reduced CO 2 emission. The hydrogen can be used to reduce CO 2 from coal-fired power plants to produce methanol which can be used as an efficient automotive fuel. The kinetics of methane decomposition is studied in a one inch diameter tubular reactor at temperatures between 700 and 900 °C and at pressures between 28 and 56 atm. The Arrhenius activation energy is found to be 31.3kcal/mol of CH 4. The rate increases with higher pressures and appears to be catalyzed by the presence of carbon particles formed. The conversion increases with temperature and is equilibrium limited. A thermodynamic study indicates that hydrogen produced by methane decomposition while sequestering the carbon produced requires the least amount of process energy with zero CO 2 emission. Application to methanol synthesis by reacting the hydrogen with CO 2 recovered from coal burning power plant stack gases can significantly reduce CO 2 from both the utility and transportation sectors. Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.

Methanol as an agent for CO2 mitigation

Abstract The Carnol System consists of methanol production by CO2 recovered from coal fired power plants and natural gas and the use of the methanol as an alternative automotive fuel. The Carnol Process produces hydrogen by the thermal decomposition of natural gas and reacting the hydrogen with CO2 recovered from the power plant. The carbon produced can be stored or used as a materials commodity. A design and economic evaluation of the process is presented and compared to gasoline as an automotive fuel. An evaluation of the CO2 emission reduction of the process and system is made and compared to other conventional methanol production processes including the use of biomass feedstock and methanol fuel cell vehicles. The CO2 emission for the entire Carnol System using methanol in automotive IC engines can be reduced by 56% compared to the conventional system of coal fuel power plants and gasoline driven engines and by as much as 77% CO2 emission reduction when methanol is used in fuel cells for automotive purposes. The Carnol System is shown to be an environmentally attractive and economically viable system connecting the power generation sector with the transportation sector which should warrant further development.

The Hy-C process (thermal decomposition of natural gas) potentially the lowest cost source of hydrogen with the least CO2 emission

The Hy-C process (thermal decomposition of natural gas) potentially the lowest cost source of hydrogen with the least CO2 emission

The Hy-C process (thermal decomposition of natural gas) potentially the lowest cost source of hydrogen with the least CO 2 emission

The abundance of natural gas as a natural resource and its high hydrogen content make it a prime feedstock candidate for a low cost supply of hydrogen. The thermal decomposition of natural gas by methane decomposition produces carbon and hydrogen. Conventional steam reforming of natural gas produces CO 2 and hydrogen and requires more process energy. Methane decomposition produces the least amount of greenhouse gas CO 2 emissions per unit of hydrogen and can be totally eliminated when the carbon produced is sequestered or sold as a material.

Modifications du spectre de pores de graphites artificiels densifies par craquage de gaz naturel. Etude au moyen d'un nouveau porosimetre a absorption γ

A brief description is given of a new mercury porosimeter, using γ-beam absorption. This apparatus allows measurements of local heterogeneities in pore size distribution. It has been used to study the changes in pore size distribution after deposition of a pyrocarbon inside of the pores of conventional nuclear graphites. The deposits were obtained by thermal decomposition of natural gas, under normal pressure, at temperature around 1000°C. The influence of main parameters such as the gas flow, hydrogen content and initial pore size distribution was studied. Such modification of pore size distribution seems to be an interesting way of reducing the radiolytic corrosion of graphites in CO 2.

Some Properties of Carbon Black

Abstract The term “carbon black” will be used in this paper to include all the varieties of moderately pure carbon existing in the form of soot. So far as the rubber industry is concerned, four distinct types of carbon black are in general use, as follows: (1) Gas Black.—Sometimes itself called carbon black, made by the incomplete combustion of natural gas, the principal component of which is methane. The flames of burning gas impinge on metal surfaces, on which the black is deposited. (Cf. Neal and Perrott, Bull. No. 192, United States Bureau of Mines, 1922.) (2) Acetylene Black.—Produced by the explosive combustion of purified acetylene in closed chambers. (3) Lamp Black.—Obtained by incomplete combustion of fats, oils, tars, etc. Unlike the gas black particles, which are removed from the interior of the flame, those of lamp black pass through the outer layer before deposition. (Twiss, India Rubber J., 65, 607, 651, 393 (1923)). (4) Thermatomic Black.—Made by thermal decomposition of natural gas out of contact with air. The difference in physical properties of these blacks depends largely on differences in heat treatment during manufacture. They are arranged above in order of the size of the individual particles, those of gas black easily averaging the smallest.