Improve Process Economics Research Articles

Biological treatment of condensate from aerobic digestion of biodegradable waste: A German example

AbstractSeparation of household waste into recyclable, biodegradable, and nonbiodegradable components is required in Germany. Aerobic digestion of the biodegradable component can further minimize the waste volume. During aerobic digestion a hot humid exhaust stream, containing volatile organic and other low molecular weight compounds, is produced. Cooling this stream produces up to 350 L of condensate per ton of biodegradable feed material. Efficient treatment of this condensate is essential for a practical aerobic digestion process. Reuse of the condensate could lead to improved process economics. In this paper, condensate treatment by biological degradation using intermittent sparging has been investigated. An inorganic ultrafiltration membrane was used to separate the biomass from the treated water. It is shown that this one‐step intermittent nitrification/denitrification process may be used to reduce COD, total nitrogen, and ammonia nitrogen concentrations to acceptable values for direct discharge of the treated water into rivers. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 215–221, 2004

Antibodies and genetically engineered related molecules: production and purification.

Antibodies and antibody derivatives constitute 20 % of biopharmaceutical products currently in development, and despite early failures of murine products, chimeric and humanized monoclonal antibodies are now viable therapeutics. A number of genetically engineered antibody constructions have emerged, including molecular hybrids or chimeras that can deliver a powerful toxin to a target such as a tumor cell. However, the general use in clinical practice of antibody therapeutics is dependent not only on the availability of products with required efficacy but also on the costs of therapy. As a rule, a significant percentage (50-80%) of the total manufacturing cost of a therapeutic antibody is incurred during downstream processing. The critical challenges posed by the production of novel antibody therapeutics include improving process economics and efficiency, to reduce costs, and fulfilling increasingly demanding quality criteria for Food and Drug Administration (FDA) approval. It is anticipated that novel affinity-based separations will emerge from the development of synthetic ligands tailored to specific biotechnological needs. These synthetic affinity ligands include peptides obtained by synthesis and screening of peptide combinatorial libraries and artificial non-peptidic ligands generated by a de novo process design and synthesis. The exceptional stability, improved selectivity, and low cost of these ligands can lead to more efficient, less expensive, and safer procedures for antibody purification at manufacturing scales. This review aims to highlight the current trends in the design and construction of genetically engineered antibodies and related molecules, the recombinant systems used for their production, and the development of novel affinity-based strategies for antibody recovery and purification.

A study of die failure mechanisms in aluminum extrusion

A very important factor contributing to the performance and economics (efficiency and quality) of any hot metal-forming process is the service life of tooling. Product rework and rejects can be traced back to various defects spread over the die life-cycle: die design, die manufacture, heat treatment and die service. Initiation and propagation of die damage can be caused by a number of mechanisms. Analysis of tool and die failure thus plays an important role in the prediction and prevention of die failure, and subsequently in improving process economics. This depends to a large extent on the knowledge of the manufacturing and service history of the failed tool and die. Such information is generally not very easily available, and especially not for a large number of die failures and a large spectrum of die profiles. Very few articles are available in literature that present failure analysis based on a substantial sample size of real die breakdowns. The three most commonly reported modes of die failure are fatigue-based fracture, wear, and plastic deformation/deflection. Shape complexity of the die profile plays an important role in hot extrusion of aluminum alloys. The paper presents results of an ongoing study about the relationship between die profile and modes of die failure. A total of 616 die failures involving 17 different die profiles were studied, in collaboration with a local industrial setup. All dies were made of H-13 steel, while the billet material was Al-6063 in all the cases. The analysis presented here reflects three different perspectives: (a) overall and class-wise break-up of failure modes, (b) failure analysis for dies of different complexities, and (c) shape-wise breakdown of each failure mode.

The Effect of the Liquid-Phase Activity Model on the Simulation of Ethyl Acetate Production by Reactive Distillation

Reactive distillation is an attractive way of improving process economics by combining distillation and reaction, especially for equilibrium-limited reactions such as esterification. Reactive systems are more nonideal than conventional ones, thus, they need elaborate models that consider the nonideality of the vapor and liquid phases. Among abundant liquid-phase activity models, modified versions of UNIFAC are cited as being well-suited for this purpose. In this paper, four activity models are compared by means of a simulation model applied to the production of ethyl acetate. It is found that the two versions of UNIFAC give similar results.

Calculation of the efficiency of purification by crystallization of ideal multicomponent stereoisomeric mixtures

A method for evaluating the maximum theoretical recovery of pure component from a stereoisomeric mixture by crystallization is discussed. The approach is based on the approximation of ideal behaviour as exemplified by the Schroeder–van Laar equation for conglomerates, and the Prigogine–Defay equation for racemic compounds. These equations are used to calculate the n-dimensional eutectic. It is shown that the n-dimensional eutectic is more soluble than the ( n−1)-dimensional eutectic. A calculation is performed which removes only the n-dimensional eutectic from the sample and calculation of recovery through this discrete purification step is possible. After this, a system of n−1 components is obtained. The calculation may be repeated until only one component remains. The overall recovery of pure isomer is the product of the recoveries at each discrete purification step. The procedure is well suited to computer algorithm and a summary listing is presented. A series of example calculations are included for reference purposes. The methodology is intended to be useful in guiding efforts to improve process economics.

Examination of eastern US oil shale by-products and their markets

Established and potential oil shale product and by-product markets are examined in an effort to identify components or process configurations that might improve process economics and to evaluate promising directions for future research. These include trace elements, sulfur, cement, asphalt, bricks, fixed gases, specialty carbon fibres, adsorbent carbons, chemicals and chemical feedstocks. Market evaluations for the most part are based on the yields of by-products expected from an eastern US oil shale using Kentort fluidized-bed technology in a 6800 t day −1 plant. For certain value-added products such as specialty fibres and adsorbent carbons, the discussion is more general.

Bioprocessing of commodity chemicals research directions for government, industry, and academia

The US chemical industry is facing maturing markets, variability in raw materials supply, and stiff competition from emerging chemical industries in other countries with abundant feedstock supplies. Bioprocessing could play a major role in the domestic industry’s attempt to rejuvenate many of its mature segments. Potential advantages of bioprocessing include new products, improved process economics, reduced environmental hazard, and feedstock flexibility. However, socio-institutional factors and technical constraints must be resolved before routine commercial production of bulk chemicals by bioprocessing is possible. Important research directions include improvements in biocatalysts, design of innovative bioreactors, and developments in new separations technology. Both government and academic resources are available to assist the commodity chemicals industry in solving these research challenges.

Umweltfreundlichere Produktionsverfahren in der chemischen Industrie

AbstractEnvironmentally more acceptable processes in the chemical industrys. From its very beginning the chemical industry has always made every effort to cut the consumption of raw materials and energy in its processes and to diminish the release of by‐products and waste streams into the environment. These efforts at technically improving the various processes are presently being intensified by economical and political pressures of rising raw material costs and the rising costs of releasing harmful substances into the environment. Ways of reducing these influences on the environment by chemical processes and of improving process economics will be reported from the experience of Bayer AG. The examples show that it is possible to combine the indispensable with the practicable, and that in this way the burden on the environment can be kept as low as may be consistent with the image of the industrial society.

Principles of vacuum distillation of metal mixtures

Recently, the methanol production has received a lot of attraction in the process industries due to its wide applications in the synthesis of many commercial chemicals and fuels. Most of the coal to methanol processes suffers from higher water consumption, greenhouse gas (GHG) emissions and lower yields. The aim of this study is to develop a novel energy efficient and economic viable process that may not only increase the methanol production capacity but also offers the less energy requirements with improved process economics. In this study, coal gasification process is sequentially integrated in the parallel design configuration with the natural gas reforming technology to enhance the heating value of the resulting syngas for methanol production. To achieve this aim, two case studies have been developed and compared in terms of overall process performance and economics. Case 1 represents the conventional coal to methanol process, whereas, case 2 represents the conceptual design of integrating the gasification and reforming technologies for enhanced methanol production. The process efficiencies calculated for case 1 and case 2 is 63.2% and 70.0%, respectively. It has been seen from results that the methanol production energy for case 1 and case 2 is 0.69 kg/W and 0.76 kg/W, respectively. In terms of process economics, the methanol production cost for case 1 and case 2 has been estimated as 250 €/tonne and 234 €/tonne, respectively. The comparative analysis showed that the case 2 design not only offers higher process performance but also enhances the process feasibility compared to the conventional coal based processes.