High temperature dewatering of ethanol by vapour permeation and pervaporation with HybSi® membranes

Ethanol is one of the most important commodity chemicals used in a broad range of applications and can be produced by the hydrolysis of ethylene, though by far the largest fraction of ethanol is produced via fermentation mainly using 1st generation feedstock. Regardless of the source of the ethanol, from fermentation or from direct hydration of ethylene, the product is normally a dilute aqueous solution. The product is fed to a distillation system to concentrate ethanol. The separation of ethanol and water is complicated because ethanol and water form an azeotrope at 95.6 weight% ethanol. It is not possible to produce pure ethanol from an azeotropic mixture by normal distillation. Pervaporation is a method for dehydration of organics such as ethanol, which substantially avoids drawbacks of azeotropic distillation and adsorption. As the pervaporation process is not governed by thermodynamic equilibria and the selectivity is determined by the difference in permeation rates of components through the membrane, mixtures of components with close boiling points and azeotropic mixtures can be effectively separated. Pervaporation exhibits its highest efficiency in a concentration range of the ethanol-water mixture where distillation is least effective, namely, at high ethanol concentrations of 90-95 wt.%, especially in the vicinity of the azeotropic concentration. Previous studies have shown that hybrid distillation processes combined with either pervaporation or vapour permeation can be very attractive for the separation of liquid mixtures. Such a hybrid process leads to large energy savings when the membrane is used for breaking the azeotrope. At the preferred process conditions currently available commercial polymer and zeolite membranes cannot be used. In this study, the focus is on membrane stability at higher operating temperatures in a water ethanol mixture for sol–gel derived Hybsi® membranes and the membrane performance in pervaporation and vapour permeation. The stability of the membranes is one of the crucial factors of their application in industrial separation processes. A comparison between pervaporation and vapour permeation has been made in which water removal from ethanol has been used as an example. By applying higher temperatures and thus higher driving forces in the membrane unit the required membrane area and the total costs of the process are strongly reduced. The comparison was based on endurance tests, in the dehydration of ethanol at 150°C. The high hydrothermal and chemical stability of the membrane was proven in continuous measurements (24/7) that lasted for periods of over 500 days. The membrane performance was followed during this period of time by measuring the flux and membrane selectivity. Both in pervaporation and vapour permeation a good and stable membrane performance was obtained after a stabilisation period and from a flux and selectivity point of view at 150°C both membrane operation options show similar results. Detailed test results will be presented. For ethanol dehydration vapour permeation would be preferred above pervaporation as advantage can be taken of the vapour already present at the top of the distillation column which will still be used to remove major part of the water present. The presented results show that HybSi® membranes are applicable in the dehydration of ethanol by pervaporation and vapour permeation at higher temperatures. The high temperature use leads to a broadened application window and will open up markets that have so far been inaccessible for commercially available pervaporation and vapour permeation membranes

Lab and pilot scale pervaporation process for the purification of dimethyl carbonate

The separation of dimethyl carbonate (DMC) from methanol is of great industrial interest, as DMC can be prepared from urea (made from captured CO2 and ammonia) and methanol with methanol also acting as a solvent for the reaction. As a result relative low levels of DMC in methanol can be obtained. The purification is a very energy intensive process with the base case being a pressure swing distillation method. The use of polymeric membranes for this purpose is not recommended as the driving forces for the transport of methanol are fairly low, which asks for high operating temperatures of over 120°C. These conditions call for a ceramic membrane. Zeolitic membranes are typically not suited for the transportation of methanol and polymeric membranes are not stable under these conditions. Hybrid silica membranes, such HybSi® can combine high operation temperatures, with sufficient high selectivities and high permeances. In the current study, we have performed process simulations to assess the potential reduction in CAPEX and OPEX when a HybSi® membrane is included in the process. The costs of the separation of DMC from methanol has been assessed by Aspen Plus flow sheeting using the by ECN developed Pervatool to simulate the behavior of the membrane pervaporation process. The calculations were based on actual lab scale membrane performance data and vapor-liquid-equilibrium data originating from internal and published sources. To facilitate a transparent comparison, the total costs of the purification were calculated per ton of DMC produced. The cost saving is as high as 45% when a hybrid process is being used that combines membranes and distillation as compared to the base case with pressure swing distillation, see Table 1. Cost reductions can be found in both the OPEX and the CAPEX and range from 25 to 55%. The OPEX savings can be ascribed to a strongly reduced energy consumption, while the CAPEX reduction is ascribed to a much more compact design with smaller distillation columns. The values are dependent on the way of calculation, e.g. absolute numbers or relative to the amount of DMC produced, and on technical factors such as the DMC content in the methanol recycle and various process conditions throughout the separation train. These simulations have been supported by long term measurements at lab scale as well as a pilot testing in a fully specialized plant using about 0.7 m2 of membrane area. In the presentation all the relevant results will be discussed of the process simulations and the lab and pilot scale testing. Table 1: Purification costs per ton DMC produced taking into account both CAPEX and OPEX Relative purification costs per ton DMC produced Relative cost reduction Base case with high purity recycle 100 Base case with low purity recycle 96 4% Membrane case with high purity recycle 72 28% Membrane case with low purity recycle 55 45

Audio watermarking for monitoring and copy protection

Based on existing technology used in image and video wa-termarking, we have developed a robust audio watermark-ing technique. The embedding algorithm operates in fre-quency domain, where the magnitudes of the Fourier co-efficients are slightly modified. In the temporal domain, an additional scale parameter and gain function are neces-sary to refine the watermark and achieve perceptual trans-parency. Watermark detection relies on the Symmetrical Phase Only Matched Filtering (SPOMF) cross-correlation approach. Not only the presence of a watermark, but also its cyclic shift is detected. This shift supports a multi-bit payload for one particular watermark sequence. The water-marking technology proved to be very robust o a large num-ber of signal processing "attacks " such as MP3 (64 kb/s), all-pass filtering, echo addition, time-scale modification, re-sampling, noise addition, etc. It is expected that this ap-proach may contribute in a wide variety of existing (e.g. monitoring and copy protection) and future applications

Biomechanical assessment of the effects of decompressive surgery in non-chondrodystrophic and chondrodystrophic canine multisegmented lumbar spines

Purpose Dogs are often used as an animal model in spinal research, but consideration should be given to the breed used as chondrodystrophic (CD) dog breeds always develop IVD degeneration at an early age, whereas nonchondrodystrophic (NCD) dog breeds may develop IVD degeneration, but only later in life. The aim of this study was to provide a mechanical characterization of the NCD [non-degenerated intervertebral discs (IVDs), rich in notochordal cells] and CD (degenerated IVDs, rich in chondrocyte-like cells) canine spine before and after decompressive surgery (nucleotomy). Methods The biomechanical properties of multisegmented lumbar spine specimens (T13-L5 and L5-Cd1) from 2-year-old NCD dogs (healthy) and CD dogs (early degeneration) were investigated in flexion/extension (FE), lateral bending (LB), and axial rotation (AR), in the native state and after nucleotomy of L2-L3 or dorsal laminectomy and nucleotomy of L7-S1. The range of motion (ROM), neutral zone (NZ), and NZ stiffness (NZS) of L1-L2, L2- L3, L6-L7, and L7-S1 were calculated. Results In native spines in both dog groups, the greatest mobility in FE was found at L7-S1, and the greatest mobility in LB at L2-L3. Surgery significantly increased the ROM and NZ, and significantly decreased the NZS in FE, LB, and AR in both breed groups. However, surgery at L2-L3 resulted in a significantly larger increase in NZ and decrease in NZS in the CD spines compared with the NCD spines, whereas surgery at L7-S1 induced a significantly larger increase in ROM and decrease in NZS in the NCD spines compared with the CD spines. Conclusions Spinal biomechanics significantly differ between NCD and CD dogs and researchers should consider this aspect when using the dog as a model for spinal research. © Springer-Verlag 2012

Перспективи розвитку світової енергетики й забезпечення енергетичної безпеки України

Проблеми забезпечення енергетичної безпеки (ЕнБ) безпеки були та залишаються головними складовими забезпечення національної безпеки та загального сталого розвитку

Tuberculosis-HIV Co-infection in Kiev City, Ukraine

In 2004, we tested all patients with newly diagnosed tuberculosis (TB) for HIV in Kiev City. The results were compared to information from medical records of 2002, when co-infection prevalence was 6.3%. Of 968 TB patients, 98 (10.1%) were HIV infected. TB-HIV co-infection is increasing, especially in injecting drug users

Weekly high-dose cisplatin is a feasible treatment option: Analysis on prognostic factors for toxicity in 400 patients

In the present study we describe the toxicity of weekly high-dose (70-85 mg m-2) cisplatin in 400 patients (203 men, 197 women; median age 54 years) with advanced solid tumours treated in the period 1990-2001 who took part in phase I/II trials, investigating the feasibility and efficacy of weekly cisplatin alone, or in combination with paclitaxel or etoposide. Cisplatin was administered in 250 ml NaCl 3% over 3 h, for six intended administrations. The mean number of administrations was 53 (range, 1-6 administrations). Reasons not to complete six cycles were disease progression (7.5%), haematological toxicity (9%), nephrotoxicity (7%), ototoxicity (2.5%), neurotoxicity (1%), gastrointestinal toxicity (1%), cardiovascular complications (0.5%) or a combination of reasons including noncompliance and patient's request (5.5%). Logistic regression analysis was used to evaluate baseline parameters for prognostic value regarding toxicity. Leukopenia correlated with etoposide cotreatment, and thrombocytopenia with cisplatin dose and prior (platinum-based) chemotherapy. Risk factors for nephrotoxicity were older age, female gender, smoking, hypoalbuminaemia and paclitaxel coadministration. Neurotoxicity >grade I (11% of patients) was associated with prior chemotherapy and paclitaxel coadministration. Symptomatic hearing loss occurred in 15% with anaemia as the predisposing factor. We conclude that weekly high-dose cisplatin administered in hypertonic saline is a feasible treatment regimen

Standard Outpatient Re-Evaluation for Patients Not Admitted to the Hospital After Emergency Department Evaluation for Acute Abdominal Pain

The aim of the present study was to investigate the efficacy and safety of standard outpatient re-evaluation for patients who are not admitted to the hospital after emergency department surgical consultation for acute abdominal pain. All patients seen at the emergency department between June 2005 and July 2006 for acute abdominal pain were included in a prospective study using a structured diagnosis and management flowchart. Patients not admitted to the hospital were given appointments for re-evaluation at the outpatient clinic within 24 h. All clinical parameters, radiological results, diagnostic considerations, and management proposals were scored prospectively. Five-hundred patients were included in this analysis. For 148 patients (30%), the final diagnosis was different from the diagnosis after initial evaluation. Eighty-five patients (17%) had a change in management after re-evaluation, and 20 of them (4%) were admitted to the hospital for an operation. Only 6 patients (1.2%) had a delay in diagnosis and treatment, which did not cause extra morbidity. Standard outpatient re-evaluation is a safe and effective means of improving diagnostic accuracy and helps to adapt management for patients that are not admitted to the hospital after surgical consultation for acute abdominal pain at the emergency department.Vascular Surger