Electrolysis Plant Research Articles

A possible method of improving energy efficient para-LH2 production

Abstract Liquid hydrogen as a superior transport fuel, and bulk hydrogen as a desirable input for conversion of fossil fuel reserves to more convenient liquid hydrocarbons, points to the value of developing energy efficient means for producing liquid hydrogen. A feasibility study is made of a high-pressure water electrolysis and hydrogen liquefaction plant, in which the oxygen by-product is expanded to provide additional work and cooling. Performance is compared with ideal thermodynamic processes.

Recent trends in hydrogen energy in canada with a focus on work at the Institut de Recherche d'Hydro-Qúebec (IREQ)

Recently, there has been a great deal of interest in Canada in emphasizing the research, development and demonstration efforts on themes bearing on hydrogen energy. A brief outline of different aspects of this interest in hydrogen technologies, as expressed by a number of leading public bodies, is given in the context of features particular to the energy situation in Canada. This is followed by a synopsis of the hydrogen activity in Quebec, with a description of the work at Institut de recherche d'Hydro-Québec (IREQ), the largest non-university centre of electrochemical and hydrogen-related research in Canada. This work, which started in 1970 and has gained a steady momentum since, comprises the following topics: electrocatalysis and the fundamental electrochemical physics of charge transfers at electrodes; photoelectrolysis; aspects of thermal and combined decomposition cycles in hydrogen production; hydrogen storage by liquid hydrides; intermittent electrical energy (as produced, e.g. by windmills) storage concepts involving electrolysers; testing (either previously or currently) of fuel cells and advanced experimental electrolysis plants; work on electrochemical monitors for the detection of hydrogen; and, finally, proposed demonstration electrolyser plants in the several megawatt range. Some of this work, e.g. on commercial electrolysers, involves cooperative arrangements with the equipment manufacturers, namely, the Electrolyser, Inc. and its parent companies, the Noranda and Electrolyser Corporations.

Studies on the reaction of aqueous inorganic mercury with organic substances in an Hg-type Cl 2-caustic electrolyser and its associated processes: Possibility of formation of methyl mercury (II) chloride (MMC)

Experiments were carried out on the possibility of the formation and decomposition of methyl mercury (II) chloride (MMC) in each process in a mercury-type Cl 2-caustic electrolysis plant. The results obtained were as follows: (1) MMC was not formed through the reaction of aqueous inorganic mercurials with any material or compound such as carbon black, organic impurities in rock salt or organic coagulating agents. (2) 0·001 ppm of MMC was decomposed when either chlorine evolved at the anode or when 10–100 ppm of HClO was present in circulating brines. Therefore, it was concluded that there is little possibility of the formation of MMC in a mercury-type Cl 2-caustic electrolysis plant.

Problemloesungen mit ionenaustauschern

AbstractTwo special ionexchange resins are described. One for the polishing of brine solutions in alkali chloride electrolysis plants. It is a styrene‐divinylbenzene resin with complexforming iminodiacetic acid groups. The residual calcium values in the brine can be set down from 2–20 ppm Ca to less than 0,05 ppm Ca by this resin. The second resin is a strongly basic gel typ doted with metallic palladium. This resin serves as catalyst to remove even last traces of oxygen from process water using hydrogen added in equivalent quantities.

Concepts and design for scaling up high temperature water vapour electrolysis

Based upon laboratory high temperature electrolysis experiments with single cells and serial connected electrolysis cells a concept for scaling up the system for technical applications is presented. It is shown that with regard to the specific properties of ceramic materials a tubular geometry for the electrolysis cells will be most appropriate. In contrast to flat plate cells, tubular cells can easily be connected in series with respect to electrical current as well as gas flow. A scheme for the integration of electrolysis tubes into modules and large scale electrolysis plants will be presented. With respect to the process engineering of an industrial electrolysis plant, it is shown that a near term realization is possible, without high temperature heat sources, by a slightly exothermic operation of the electrolysis cells.

Optimal Control of Electrolytic Cell by Computer - An Approach for Energy Conservation

The mercury process chlor-alkali cells whose anodes are dimensionally stable electrode have been operated in Mitsui Toatsu Chemicals, Inc. (MTC) since 1970. The control system for the mercury cell process was developed by MTC in collaboration with TOPACS Inc.(software house) for the purpose of optimum operation of electrolysis plant in 1978. The advanced benefits obtained by the system are following; 1) low energy consumption, 2) resource saving, 3) man-power saving and 4) safety operation by controlling the distance between electrodes of the cell optimal. The algorithm of the control logics is based on the mathematical model of electrolytic cell and the determination of optimum cell operation. The characteristics of the algorithm are adaptive control and interacting control for multi-variable system. Especially, on the energy conservation, this control system has realized the best mercury cell process for unit consumption of electric power in the world.

Skin Telangiectases in Workers at an Aluminum Plant

OCCUPATIONAL-HEALTH physicians from a large Canadian aluminum company recently noticed the presence of numerous telangiectases on the skin of some production workers. Called to investigate, the Workmen's Compensation Commission confirmed the presence of these lesions. Some affected workers complained of the appearance of the lesions and worried about their effects on health. Researchers from the Soviet Union have reported the presence of telangiectases in workers at an aluminum electrolysis plant,1 but the lesion has received little or no attention in the Western medical literature.We attempted to determine whether these skin lesions were related to work in aluminum and to . . .

A theoretical study of the modelling and control of a solar water electrolysis plant

The simulation of a hydrogen producing plant, consisting of semiconductor cells and conventional water electrolysis cells is described on the basis of a mathematical model. A particular control strategy for daily hydrogen production is numerically illustrated.

Hydrogen production by high temperature electrolysis of water vapour

Introducing hydrogen as a future energy carrier an important condition is a high efficient and low cost process for hydrogen production. Total efficiencies of conventional water electrolysis plants are limited to 25–28% with respect to the primary heat necessary for power generation. Significant improvements of this efficiency can be achieved by steam electrolyzing at high temperatures. The thermodynamic advantages of this high-temperature electrolysis process are shown and the technological tasks of the required development work and the state of the art are described in detail. Significant improvements of the components for construction and interconnection of electrolysis cells have been achieved. Typical measured cell characteristics are adiabatic cell voltages of 1.3 V at 0.4 A/cm 2 current density. Industrial engineering studies of the whole process have been performed indicating total efficiencies of about 40–50%, depending on the primary energy source.

A self-controlled automatic electrolysis plant for producing deuterium in a laboratory

A simple electrolysis cell of small capacity has been constructed. A needle valve system maintains a constant pressure in the cell enabling the electrolysis of heavy water to continue for hours without attention. The system also eliminates the exposure of a large amount of mercury to the atmosphere. 160 ml h-1 of D2 gas at normal pressure are collected in the reservoir under vacuum at a current of 0.4 A through the cell. Deuterium prepared in this way can be used as an RF ion source.

Determination of total mercury in air by atomic absorption spectrometry after collection on manganese dioxide

A method has been developed for the routine determination of total mercury in air. Mercury and its compounds are collected on manganese dioxide, the manganese dioxide is dissolved and the mercury is determined by atomic absorption spectrometry (cold vapour technique). The method was tested with standard samples containing elemental mercury, mercury(II) and organomercurials. The collection efficiency of the manganese dioxide is greater than 95% for concentrations up to 2 mg of mercury per m 3 of air. The lowest quantity of mercury that can be determined is 0.02 μg. The relative standard deviation calculated from experiments done in an alkali chloride electrolysis plant equipped with mercury cells, is 1.4% at the 25 μg m -3 level (collection time, 4 h).

ChemInform Abstract: OXYGEN EVOLUTION ON SEMICONDUCTING OXIDES

AbstractEine Reihe von Metalloxiden wird nach Kriterien wie Leitfähigkeit, Korrosionsbeständigkeit, Sauerstoffreduktionsvermögen sowie Gleichgewichtspotential der Metall/Metalloxid‐ oder niederes Metalloxid/ höheres Metalloxid‐Paare auf ihre Eignung als O2 ‐entwickelnde Elektroden bearbeitet.

Industrial brine production using power station waste heat to assist solar evaporation of sea water

The rate of evaporation from a slightly heated pond of sea water, over and above the rate from an unheated control pond, has been found to be about 5.6 m of depth per year, for each kW/m2 of heat density applied. In winter about 40%, and in summer about 55%, of the added heat goes to increasing evaporation. In conjunction with local data on rainfall and natural evaporation, this value can be used to predict the net evaporation from a heated pond at a chosen site. If a power station in the Auckland area had sea water cooling ponds of the usual size, the combination of natural evaporation, rainfall, and evaporation due to heating would result in a net evaporation of 1.02 m per year and production of a concentrated brine containing at least 200 000 tonnes per year of salt, for a 1400 MWe power station. The degree of concentration allowed in the cooling pond is limited by the formation of scale in the condensers. By adding trisodium phosphate (obtainable cheaply in New Zealand from a low quality phosphate ore) and ammonium chloride to the brine, the scale-forming calcium and magnesium can be precipitated as a mixture of metal phosphates and metal ammonium phosphates. The precipitate has potential value as a high-analysis fertiliser or a cattle feed supplement. At the same time a non-scaling brine is produced, which can safely be concentrated five-fold in a power station cooling pond. The brine is then suitable as feed for a caustic/chlorine electrolysis plant. A portion of the caustic soda product must be recycled to the preparation of the trisodium phosphate.

Industrial brine production using power station waste heat to assist solar evaporation of sea water

AbstractThe rate of evaporation from a slightly heated pond of sea water, over and above the rate from an unheated control pond, has been found to be about 5.6 m of depth per year, for each kW/m2 of heat density applied. In winter about 40%, and in summer about 55%, of the added heat goes to increasing evaporation. In conjunction with local data on rainfall and natural evaporation, this value can be used to predict the net evaporation from a heated pond at a chosen site. If a power station in the Auckland area had sea water cooling ponds of the usual size, the combination of natural evaporation, rainfall, and evaporation due to heating would result in a net evaporation of 1.02 m per year and production of a concentrated brine containing at least 200 000 tonnes per year of salt, for a 1400 MWe power station. The degree of concentration allowed in the cooling pond is limited by the formation of scale in the condensers. By adding trisodium phosphate (obtainable cheaply in New Zealand from a low quality phosphate ore) and ammonium chloride to the brine, the scale‐forming calcium and magnesium can be precipitated as a mixture of metal phosphates and metal ammonium phosphates. The precipitate has potential value as a high‐analysis fertiliser or a cattle feed supplement. At the same time a non‐scaling brine is produced, which can safely be concentrated five‐fold in a power station cooling pond. The brine is then suitable as feed for a caustic/chlorine electrolysis plant. A portion of the caustic soda product must be recycled to the preparation of the trisodium phosphate.

Oxygen evolution on semiconducting oxides

The oxygen evolution reaction is of particular interest to secondary metal air batteries and water electrolysis plants. However, most of the earlier work has been on precious metals and there are no guidelines for the choice of semiconducting oxides as oxygen evolving electrodes. In this study, the role of the metal/metal oxide or the lower metal oxide/higher metal oxide couple in determining the minimum voltage required for the evolution of oxygen is emphasized, together with other essential requirements such as electrical resistivity, electrode microstructure, corrosion resistance and catalytic properties. A survey of various metal oxides based on the above criterion suggested that NiCo 2O 4 is of particular interest and Teflon bonded electrodes based on this material gave over 13000 A/m 2 at 1.63 V vs dhe, 70°C, 5 N KOH.

Activation analysis of mercury in urine samples of electrolysis cell workers.

The activation method of determination of trace amounts of Hg in human urine has been studied by introducing a simple amalgam deposition method. Human urine samples were obtained from the alkali chloride, electrolysis plant equipped with Hg cells. The capacity of Cu powder for Hg quantity, the pH conditions, and the shaking time were described. The results showed that the Hg contents in workers' urine samples varied from 33 ppb to 60 ppb depending on working conditions.

Conceptual design of large scale water electrolysis plant using solid polymer electrolyte technology

In an energy conscious environment, the key to the applicability of water electrolysis as a means for generation of hydrogen in bulk quantities is the achievement of high efficiencies (i.e. over 90%) at high enough current densities to keep the capital costs within economic bounds. The solid polymer electrolyte (SPE) water electrolysis technology developed by the General Electric Company is now demonstrating these efficiencies at current densities up to 500 A ft −2, and the results of recent laboratory testing show a potential for increasing this to 2000 A ft −2 within the next 10 years. This capability now makes water electrolysis one of the most promising methods for generating hydrogen from nuclear, solar or other non-fossil fuel energy sources. The performance and life test results are shown including laboratory cells on which future performance projections are based. The design and development status of a scaled-up electrolysis cell suitable for large-sized hydrogen generation plants is described. Estimated capital costs and operating costs are projected from which the resultant hydrogen costs are calculated.

Determination of total mercury in workroom air by atomic absorption or x-ray fluorescence spectrometry after collection on carbon-loaded paper

The routine determination of total mercury in workroom air of an alkali chloride electrolysis plant equipped with mercury cells, is described. The procedure is based on atomic absorption spectrometry (a.a.s.) (cold vapour technique) or x-ray fluorescence spectrometry (x.r.f.s.) after collection on carbon-loaded paper fixed in a disposable Millipore filter holder. The lowest quantity of mercury that can be determined is 0.2 μg by a.a.s. and 2 μg by x.r.f.s. Samples taken in the plant gave a relative standard deviation of about 2 % for a.a.s. and 3 % for x.r.f.s.

Standardization of methods for the determination of traces of mercury : Part I. Determination of total inorganic mercury in inorganic samples

A method is described for the routine determination of mercury in the process and product streams of chlor alkali electrolysis plants (with the exception of chlorine) and also in the plant waste waters. The procedure is based on flameless atomic absorption spectrophotometry. Results for interlaboratory trials involving up to 37 participating laboratories are presented. Both synthetic and technical samples were analysed with mercury contents varying between 20 μg kg -1 and 20 mg kg -1. Statistical evaluation of the results gave a value of from 4 to 8% for the repeatability and from 6 to 22% for the reproducibility.

Determination of sodium in sodium amalgam by measurement of the thermo-electric potential

A fast method for the determination of the sodium content of sodium amalgam is based on the almost linear part of the relationship between the thermo-electric potential (T.E.P.) and the sodium content. An apparatus was constructed which has been successfully used in a mercury-brine electrolysis plant for several months. The speed of analysis is 120 samples/h. The mean deviation is ± 5% for the sodium content range of 0.1 to 0.4% by weight.