Electron impact dissociation of CO2 (a review)

Based on a detailed analysis and generalization of the results of calculations of the energy spectrum of electrons using different models in gas discharges in pure carbon dioxide CO2 and in mixtures containing CO2 , the rate constant of CO2 dissociation by electron impact in a gas discharge of direct current at atmospheric pressure is found. It is shown that, at values of the reduced electric field from 55 Td to 100 Td, the predominant mechanism of decomposition of the CO2 molecule is the collision of CO2 molecules with electrons. An expression is obtained for calculating the rate constant of CO2 dissociation by electron impact as a function of the reduced electric field.

A Comparison of Partial Discharge Sensors for Natural Gas Insulated High Voltage Equipment

The research in this paper consists of practical experimentation on a gas insulated section of high voltage equipment filled with carbon dioxide and technical air as a direct replacement to sulphur hexafluoride (SF6) and analyses the results of PD measurement by way of internal UHF sensors and external HFCTs. The results contribute to ongoing efforts to replace the global warming gas SF6 with an alternative such as pure carbon dioxide or technical air and are applicable to mixtures of electronegative gases that have a high content of buffer gas including carbon dioxide. The experiments undertaken involved filling a full-scale gas insulated line demonstrator with different pressures of CO2 or technical air and applying voltages up to 242 kV in both clean conditions and particle contaminated conditions. The results show that carbon dioxide and technical air can insulate a gas section normally insulated with SF6 at phase-to-earth voltage of 242 kV and that both HFCT and UHF sensors can be used to detect partial discharge with natural gases. The internal UHF sensors show the most accurate PD location results but external HFCTs offer a good compromise and very similar location accuracy.

Co-production of pure hydrogen, carbon dioxide and nitrogen in a 10 kW fixed-bed chemical looping system

Fixed-bed chemical looping for the generation of high purity hydrogen with sequestration of pure carbon dioxide and nitrogen.

Direct Carbon Fuel Cell-Cleaner and Efficient Future Power Generation Technology

Increasing greenhouse effect due to the burning of fossil fuels has stirred the attention of researchers towards cleaner and efficient technologies. Direct carbon fuel cell (DCFC) is one such emerging technology that could generate electricity from solid carbon like coal and biogas in a more efficient and environmental-friendly way. The mechanism involves electrochemical oxidation of carbon to produce energy and highly pure carbon dioxide. Due to higher purity, the produced carbon dioxide can be captured easily to avoid its release in the environment. The carbon dioxide is produced in a gaseous state while the fuel used is in a solid state. Due to different phases, all of the fuel can be recovered from the cell and can be reused, ensuring complete (100%) fuel utilization with no fuel losses. Moreover, DCFC operates at a temperature lower than conventional fuel cells. The electric efficiency of a DCFC is around 80% which is nearly double the efficiency of coal thermal plant. In addition, DCFC produces pure carbon dioxide as compared to the thermal power plant which reduces the cost of CO2 separation and dumping. In different types of DCFCs, molten carbon fuel cell is considered to be superior due to its low operating temperature and high efficiency. This paper provides a comprehensive review of the direct carbon fuel cell technology and recent advances in this field. The paper is focused on the fundamentals of fuel cell, history, operating principle, its types, applications, future challenges, and development.

Bioleaching for Removal of Chromium and Associated Metals from LD Slag

The ability of Acidithiobacillus ferrooxidans to remove chromium and other metals from LD slag was examined. Additionally the option to retrieve P from LD slag was evaluated. Due to the facts that A. ferrooxidans is a facultative anaerobic microorganism and LD slag is an alkaline and oxidic material, both oxidative and reductive bioleaching experiments were carried out. In the reductive mode, four different gas atmospheres (nitrogen, carbon dioxide, air and a mixture of N2 and CO2) were considered. Promising results were obtained by reductive bioleaching with A. ferrooxidans and a pure carbon dioxide atmosphere, 83 % chromium could be removed. In comparison, only 27 % Cr were removed by oxidative bioleaching. The degree of P removal could not be easily determined due to imbalanced data obtained.