UMBAU DER 150 MW DAMPFTURBINEN IN HEIZTURBINEN IM WÄRMEKRAFTWERK DONAU

This feasibility study is concerned with the transformation of three 150 MW condensing steam turbines, working in the Dunamenti Thermal Power Station, in extraction condensing turbines for the district heating of South Budapest. In the paper the main parameters of extraction working are given

Production of the Enzyme Cyclodextrin Glycosyltransferase Using Different Fermentation Techniques

Cyclodextrins produced by cyclodextrin glycosyltransferase (CGTase) are widely used in the pharmaceutical industry to improve the solubility of drug substances as well as protect them against oxidation. The use of this enzyme in the cosmetics industry is also significant. CGTase is an enzyme that belongs to the α-amylase family, which is part of the group of non-Leloir glycosyltransferases. Enzyme-catalysed transglycosylation reactions may involve cyclization, coupling and disproportionation processes. The enzyme CGTase is mostly used to produce cyclodextrins (CDs). CGTase can produce α-, β- and γ-CDs during transglycosylation reactions, depending on the number of glucopyranose units involved (6, 7 or 8). The enzyme CGTase can also be used for enzymatic bioconversion, e.g., in the development of alternative sweeteners, where the bitter aftertaste of the product is reduced during the enzymatic bioconversion of steviol glycosides, thereby obtaining an even sweeter and more advantageous material. In our research, the enzyme CGTase was produced using different fermentation techniques to compare the activity and amount of CGTase produced by each process and optimize the subsequently planned scale-up. In our studies, the strain DSM 13 of Bacillus licheniformis was used, which produced CGTase extracellularly. During the experiments the batch, fed-batch and semi-continuous fermentation techniques were compared in terms of enzymatic production. All cultivation processes were carried out in a desktop lab scale fermenter

Investigations into Enzymatic Bioconversion to Form Rebaudioside A from Stevioside

Stevia rebaudiana Bertoni is a perennial shrub from South America that produces steviol glycosides which are 200-300 times sweeter than sugar. Stevioside and rebaudioside A are the main sweetening components of its leaves. Steviol glycosides are diterpenoids whose biosynthetic pathways have four steps in common with gibberellic acid formation. The most important enzyme in the biosynthetic pathway expressed by the gene UGT76G1 is referred to as UDP-glycosyltransferase 76G1. It converts stevioside into rebaudioside A. The former has a bitter aftertaste and is a poorer sweetener but is most abundant. This enzyme can be produced in a next generation recombinant way by Escherichia coli and Saccharomyces cerevisiae. Trichoderma longibrachiatum produces the enzyme β-1,3-glucanase enzyme, which can perform a transglycosylation between stevioside to gain rebaudioside A. In our study, a full-factorial statistical experimental design that applies different glycosyl donors, temperatures, enzyme-to-substrate ratios and pH's as factors in order to achieve higher Reb A ratios in S. rebaudiana extracts after transglycosylation is reported. The presented statistical design was appropriate to indicate relevant and significant factors, providing a good basis for an upcoming experimental design of a real-world optimization

Modeling the Biosurfactant Fermentation by Geobacillus stearothermophilus DSM2313

Biosurfactants are emerging molecules in the 21st century. However, their production intensification is still required for the development of feasible bioprocesses. Therefore, this paper studies a new biosurfactant-producer, namely Geobacillus stearothermophilus DSM2313 during statistical optimization via response surface methodology. After the statistical analysis the optimal pH = 7, glucose = 50 g/L and NH4NO3 = 2 g/L concentrations were determined. The biosurfactant production of the bacteria was predicted by our developed artificial neural network. The optimal harvesting time of the broth and the emulsification index values can be predicted simultaneously with the constructed artificial neural network. The best experiment was also kinetically described, and kinetic constants observed. Surface tension and emulsification activity were measured to characterize the formed products' efficiency. Based on these results, biosurfactants from Geobacillus stearothermophilus DSM2313 can act as bioemulsifier and can be applied for example in microbial enhanced oil recovery

THE FLUCTUATING STEAM REQUIREMENTS AND FEASIBLE APPLICATION OF GAS TURBINES WITH A WASTE HEAT BOILER

We introduce a Hungarian petroleum refinery with an industrial heat requirement fluctuating between 460 MW and 150 MW and evaluate the feasibility of a 300 t/h steam producing gas turbine with heat utilizing boilers while guaranteeing the provision of necessary operational safety reserves. The most suitable solution is accomplished with a continuous loading operation of the gas turbine block, due to the small requirement of steam there is an occurrence of periodic excess, which is utilized in the 215 MW steam turbine to acquire an operational safety reserve. During the period of maximum steam requirement, an inadequate steam quantity is acquired from these steam turbines, this can be secured by extraction before reheating. From the result of this analysis, it is not practicable to fulfil the fluctuating steam requirement of the gas turbine under partial loading

Screening for the Heterotrophic Cultivation of Chlorella sorokiniana Using an Indirect Impedance Microbiological Technique

Heterotrophic culturing of microalgae is of great interest as it has the potential to produce feedstock for added-value bioproducts. The general expectation is to develop a method that can help screen for different media compositions and batch fermentation settings more easily and faster. In the current study, an indirect impedance microbiological technique was used to test the effects of various carbon and nitrogen sources on the growth of Chlorella sorokiniana. It was found that this technique has great potential to screen for heterotrophic cultivation conditions of microalgae as the metabolic rate of microorganisms can be determined by measuring the amount of CO2 produced. The BacTrac 4100® was proven to be a suitable instrument to compare several different small-scale culturing settings. Considering the relative changes in impedance observed, the initial cell cumber exhibits an inverse linear correlation with the detection time. Chlorella sorokiniana exhibited an enhanced degree of growth on yeast extract and tryptone, and preferred glucose over acetate or glycerol. An optimum rate of growth at a glucose concentration of 20 gL-1 was also determined. Our novel approach in the field of heterotrophic cultivation of microalgae envisages great prospects for the method in terms of the design of experiments in the field of media optimization

Moderne Spitzenlastkraftwerkanlage mit Preßluftenergiespeicherung von 500 MW

This paper presents a combined thermodynamic-economical analysis of a modern power plant using compressed air energy storage. The variations of the specific heat rate as well as prices of the produced energy are mainly investigated for different power plant layouts. The world`s first such power plant as well as three different variations of a new designed, modern layout are compared. The aim was to see how much the thrift of such a plant increases the replacement of the expansion train at technological level of the late `70s by a new, high-tech turbine. Another direction, which investigations are made in, is the analysis of the efficiency of different improvements to the basic cycle. All this has been made through a comparison of the variants from both thermodynamic and economical point of view

DEVELOPMENT OF INTEGRATED USE OF GAS IN ENERGETICS

Natural gas as the finest source of energy may be widely used also in energetics within integrated systems either in the direct or in the coupled energy production providing a better efficiency. There is a wide range of the coupled energy production with better efficiency depending mainly on demands' size and the way of realization