Indirectly Heated Research Articles

Adsorptive Separation of CO2 from Flue Gas by Temperature Swing Adsorption Processes

AbstractCO2 capture from fossil fueled power stations plays a major role in balancing environmental protection with economic growth. Besides absorption and membrane processes, adsorption processes allow for the removal of CO2 from flue gases and the recovery of the adsorbed CO2 with high purity. In recent years, several pressure swing adsorption as well as temperature adsorption processes have been postulated for carbon capture. In this work, an overview of the different adsorptive methods is exposed with a focus on thermally regenerated adsorption processes. Since the classical temperature swing adsorption process shows some drawbacks, indirectly heated temperature swing adsorption processes have been postulated, which can be categorized into two groups: electro‐thermal swing adsorption and indirect heat transfer.

Extended shelf life milk – One concept, different qualities: A comprehensive study on the heat load of differently processed liquid milk retailed in Austria in 2012 and 2015

Thermal time integrators (TTIs) are useful tools to describe the heat load of pasteurized, Ultra-high temperature (UHT) and emerging Extended Shelf Life (ESL) milk, which can be produced using filtration or direct/indirect heat treatment. However, threshold limits are mandatory for β-lactoglobulin in pasteurized and UHT milk, but currently not for ESL milk, for which the Austrian Food Codex grants a transition period till 2018 for dairies using indirect heating technologies. The objective of this study was to compare two sample sets of bovine milk retailed in Austria, purchased in 2012 (n = 71) and 2015 (n = 80) including pasteurized, UHT and differently processed ESL milk samples. Furosine, acid-soluble α-lactalbumin and β-lactoglobulin were determined with RP-HPLC, and lactulose enzymatically. Results were not significantly different comparing both years, but rather highlight the significance and suitability of these TTIs to distinguish between varying heat load applied on milk. Using furosine, lactulose and α-lactalbumin, a differentiation of pasteurized, filtered and directly heated ESL milk from indirectly heated ESL milk as well as from UHT milk is possible, whereas β-lactoglobulin allowed the discrimination of directly heated ESL milk from filtered ESL milk and pasteurized milk, respectively.

An indirectly heated metal oxide hot cathode with a 100-cm2 area

Results of designing of a sectioned metal oxide hot cathode with indirect heating and a total emission coating area of 100 cm2 are described. The design of the hot cathode enables control of the working surface temperature and allows one to change emission surface without replacing the whole hot cathode. The thermal test results are presented. The possibility is shown of applying the hot cathode in the uncharacteristic mode of gas discharge formation in medium vacuum conditions.

Numerical simulation of indirect heating of water by heat transfer surface area located at the heat source

Heating the water in the water tank indirectly heated water runs through the heat exchange surfaces heated by the heat source. Using mathematical modeling for indirect heating of water in the water tank was determined heating time for the selected heat exchange surface. The results obtained were compared to the 3D numerical simulation. The results of the simulations is then investigated the variation of a mathematical model to numerical simulation. The results have not yet experimentally verified on real equipment.

Effects of Reactor Design on the Torrefaction of Biomass

Torrefied biomass is a green alternative to coal, and thus the interest in the torrefaction process is rising fast. Different manufacturers are offering different patented designs of torrefier with data on varying operating and process conditions each claiming their superiority over others. The choice of torrefaction technology has become exceptionally difficult because of a near absence of a comparative assessment of different types of reactors on a common base. This work attempts to fill this important knowledge gap in torrefaction technology by reviewing available types of reactors, and comparing their torrefaction performance common basis and examining the commercial implication of reactor choice. After reviewing available patent and technologies offered, torrefiers are classified broadly under two generic groups: indirectly heated and directly heated. Four generic types of reactors, convective heating, fluidized bed, rotating drum and microwave reactor were studied in this research. Convective and fluidized beds have direct heating, rotating reactors has indirect heating while microwave involves a volumetric heating (a subgroup of direct heating) mechanism. A standard sample of biomass (25 mm diameter × 64 mm long poplar wood) was torrefied in each of these types of reactors under identical conditions. The mass yield, energy density and energy yield of the wood after torrefaction were measured and compared. Rotating drum achieved lowest mass yield but highest energy density. The difference between two direct heating, convective heating and fluidized beds was small. Microwave provided only localized torrefaction in this series of tests. Indirectly heated reactors might be suitable for a plant near the biomass source while directly heated plant would give better value at the user end.

Improved specificity of reagentless amperometric PQQ-sGDH glucose biosensors by using indirectly heated electrodes

Indirectly heated electrodes operating in a non-isothermal mode have been used as transducers for reagentless glucose biosensors. Pyrroloquinoline quinone-dependent soluble glucose dehydrogenase (PQQ-sGDH) was entrapped on the electrode surface within a redox hydrogel layer. Localized polymer film precipitation was invoked by electrochemically modulating the pH-value in the diffusion zone in front of the electrode. The resulting decrease in solubility of an anodic electrodeposition paint (EDP) functionalized with Osmium complexes leads to precipitation of the redox hydrogel concomitantly entrapping the enzyme. The resulting sensor architecture enables a fast electron transfer between enzyme and electrode surface. The glucose sensor was operated at pre-defined temperatures using a multiple current-pulse mode allowing reproducible indirect heating of the sensor. The sensor characteristics such as the apparent Michaelis constants KMapp and maximum currents Imaxapp were determined at different temperatures for the main substrate glucose as well as a potential interfering co-substrate maltose. The limit of detection increased with higher temperatures for both substrates (0.020mM for glucose, and 0.023mM for maltose at 48°C). The substrate specificity of PQQ-sGDH is highly temperature dependent. Therefore, a mathematical model based on a multiple linear regression approach could be applied to discriminate between the current response for glucose and maltose. This allowed accurate determination of glucose in a concentration range of 0–0.1mM in the presence of unknown maltose concentrations ranging from 0 to 0.04mM.

Production of syngas from biomass

The gasification of biomass is a thermal treatment which results in a high production of gaseous products and small quantities of char and ash. In the literature a large number of experimental studies concerning the gasification of biomass with air and oxygen has been presented; generally, in these processes the heat for the gasification is produced in the reactor with a partial oxidation of biomass. However, only a few data are available for the gasification with indirect heating that produces a gas richer in energy. The aim of this paper was to study the influence of the operating conditions on the gasification of biomass carried out in a pilot plant. The process consisted of a steam gasification carried out in two indirectly heated reactors in series. Some experimental results concerning thermal and catalytic runs are presented.

The Multiply Charged Ion Source with Indirectly Heated Cathode

A survey on questions related to the production of multiply charged ions with the hot cathode ion source is given. Some characteristics of the ion source with heated cathode are discussed. It is shown that the use of hydrogen as a ballast gas in the discharge gives some possibilities for increasing the intensity of beam of multiply charged ions. The perpendicular plasma pressure of the discharge column is measured and values of Te and n are estimated. From the axial distribution of the ion charge states, it is concluded that a potential well trapping ions should exist in the discharge column. It is shown that local inhomogenities of the magnetic field along the discharge column give rise to a substantial increase of the intensity of multiply charged ion beams.

The Influence of Twisted Tapes in Subcritical, Once-Through Vapor Generators in Counter flow

The swirl flow of Freon 12 in a tubular heat exchanger, indirectly heated by forced convection of water in an annular gap, is studied. Two identical situations are compared, with and without a twisted tape, to deduce the influence of the swirl flow in the particularly interesting boundary condition of indirect heating by another fluid (and not simply of uniform Joule heating). The heat transfer is greatly increased by the swirl flow, up to a factor of two at the burnout or dryout point.

Comparison of milks processed by the direct and indirect methods of ultra-high-temperature sterilization. IV. The vitamin composition of milks sterilized by different processes

SummaryA comparison was made of the effects of direct and of indirect ultra-high-temperature (UHT) processing of milk, under standardized operating conditions giving equal sporicidal effects, on some of the more labile water-soluble vitamins and on vitamin A and carotene. The effects of processing per se were negligibly small, and the method of processing was important only in so far as the presence of residual oxygen in the sterilized milk has been found to cause losses of folic acid and ascorbic acid during storage subsequent to sterilization. The incorporation of a de-aerator vessel, to reduce the oxygen level in the indirectly heated milk and so eliminate the adverse effects of oxygen during storage, had no effect on the vitamin loss occurring during heat treatment. It is concluded that milk produced by indirect heating plant incorporating a de-aerator should be similar in vitamin content to milk produced on a direct heating plant, both immediately after processing and after storage.

High Temperature Indirectly Heated Cathode Structure

High Temperature Indirectly Heated Cathode Structure