Estimation of energy demand of fermentation-based hydrogen production

The paper is concerned with estimation of heat and power consumption in a conceptual plant to produce hydrogen from sucrose-containing or starchy biomass by fermentation. A hydrogen plant connected with a sugar factory is regarded as the basic option; the sugar factory serves as a source of sucrose-containing thick juice for the hydrogen plant, where this feedstock is processed to hydrogen. As another option, a stand-alone hydrogen plant in which starch must initially be converted to fermentable glucose solution is considered. The values of key process parameters are assumed on the basis of preliminary experimental data. For both options of the hydrogen plant, heat consumption is estimated taking heat recovery in a heat exchanger network into account. Power consumption is estimated by calculating power needed for pumping of liquid and gaseous process media.     

Uncertainty techniques in liquefied natural gas (LNG) dispersion calculations

The dynamic development of the LNG sector increases the risk of major accidents. Uncontrolled releases of LNG during the processes of manufacturing, distribution, storage, and regasification can pose a serious threat to people, facilities, and the environment. Therefore, an important goal is to determine hazard zones and the extent of potential consequences associated with a release of LNG. The key issue is to estimate these with the least level of uncertainty. The largest part of uncertainty comes from the modeling of LNG release sources and performing dispersion calculations. It is connected with the application of different mathematical models, the adoption of a number of simplifying assumptions, approximations, empirical relations, constants, and a lack of knowledge.This paper proposes a general procedure for calculating the release rate and duration time of the LNG release, pool spreading, vaporization, as well as dispersion, taking into consideration the uncertainty. The procedure consists of two parts. The first part concerns the sensitivity analysis to identify the most uncertain parameters of the LNG source term and dispersion models. The second part applies to two techniques used to include the uncertainty aspects of fuzzy sets and the Monte Carlo method for calculating hazard zones. In order to provide a basis for comparison between these two approaches, the shape of the membership functions used in the fuzzy methods are the same as the shape of the probability density function used in the Monte Carlo simulation. The case study, concerning an LNG release, illustrates the application of the proposed techniques.     

Metal (Cu, Cd and Zn) removal and stabilization during multiple soil washing by saponin

The influence of multiple saponin washing on copper, cadmium and zinc removal and stability in three types of soils (loamy sand, loam, silty clay) was investigated. Distribution of metals and their mobility measured as the ratio of exchangeable form to the sum of all fractions in soils was differential. After single washing the highest efficiency of metal removal was obtained in loamy sand (82-90%) and loam (67-88%), whereas the lowest in silty clay (39-62%). In loamy sand and loam metals had higher mobility factors (44-61% Cu, 60-76% Cd, and 68-84% Zn) compared to silty clay (9% Cu, 28% Cd and 36% Zn). Triplicate washing led to increase both efficiency of metal removal and percentage content of their stable forms.In consequence, fractional patterns for metals before and after treatment changed visibly as a result of their redistribution. Based on the redistribution index, the most stable metal (mainly in residual and organic fractions) after triplicate washing was Cu in loamy sand and loam. For silty clay contaminated with Cd, effective metal removal and its stabilization required a higher number of washings.     

Distribution of inorganic bromine and metals during co-combustion of polycarbonate (BrPC) and high-impact polystyrene (BrHIPS) wastes containing brominated flame retardants (BFRs) with metallurgical dust

This study focused on the thermal degradation of polycarbonate (BrPC) and high-impact polystyrene (BrHIPS), containing different brominated flame retardants. The evolved inorganic bromine was utilized for the separation of metals present in electric arc furnace dust (EAFD). The thermal degradation of BrPC generated inorganic gaseous HBr (69%) and condensable Br₂ (31%). The bromine evolved from BrHIPS was detected almost entirely in a condensed phase as SbBr₃. When mixed with EAFD, the evolved inorganic bromine reacted immediately with the metallic components of zinc and lead, but not with iron. The best bromination efficiencies were obtained during the isothermal heating (80 min at 550 °C) of the mixtures at mass ratios of 6:1 and 9:1 w/w under oxidizing conditions. The achieved brominating rates reached 78 and 81% for zinc and 90 and 94% for lead in 6:1 and 9:1 BrPC:EAFD, respectively, and 47 and 65% for zinc and 67 and 63% for lead in 6:1 and 9:1 BrHIPS:EAFD, respectively. The oxidizing condition favored complete vaporization of the formed bromides.     

Application of fuzzy logic to explosion risk assessment

Safety and health of workers potentially being at risk from explosive atmospheres are regulated by separate regulations (ANSI/AIHA in USA and ATEX in the European Union). The ANSI/AIHA does not require risk assessment whereas it is compulsory for ATEX. There is no standard method to do that assessment. For that purpose we have applied the explosion Layer of Protection Analysis (ExLOPA), which enables semi-quantitative risk assessment for process plants where explosive atmospheres occur. The ExLOPA is based on the original work of CCPS for LOPA taking into account an explosion accident scenario at workplace. That includes typical variables appropriate for workplace explosion like occurrence of the explosive atmosphere, the presence of effective ignition sources, activity of the explosion prevention and mitigation independent protection layers as well as the severity of consequences. All those variables are expressed in the form of qualitative linguistic categories and relations between them are presented using expert based engineering knowledge, expressed in the form of appropriate set of rules. In this way the category of explosion risk may be estimated by the semi-quantitative analysis. However, this simplified method is connected with essential uncertainties providing over or under estimation of the explosion risk and may not provide real output data.In order to overcome this problem and receive more detailed quantitative results, the fuzzy logic system was applied. In the first stage called fuzzification, all linguistic categories of the variables are mapped by fuzzy sets. In the second stage, the number of relation between all variables of analysis are determined by the enumerative combinatorics and the set of the 810 fuzzy rules “IF-THEN” is received. Each rule enables determination of the fuzzy risk level for a particular accident scenario. In the last stage, called defuzzification, the crisp value of final risk is obtained using a centroid method. The final result of the risk presents a contribution of each risk category represented by the fuzzy sets (A, TA, TNA and NA) and is therefore more precise and readable than the traditional approach producing one category of risk only. Fuzzy logic gives a possibility of better insights into hazards and safety phenomena for each explosion risk scenario. It is not possible to receive such conclusions from the traditional ExLOPA calculation results. However it requires the application of computer-aided analyses which may be partially in conflict with a simplicity of ExLOPA.The practical example provides a comparison between the traditional results obtained by ExLOPA and by fuzzy ExLOPA methods.     

Tannic acid and saponin for removing arsenic from brownfield soils：Mobilization, distribution and speciation

Plant biosurfactants were used for the first time to remove As and co-existing metals from brownfield soils. Tannic acid （TA）, a polyphenol, and saponin （SAP）, a glycoside were tested. The soil washing experiments were performed in batch conditions at constant biosurfactant concentration （3%）. Both biosurfactants differed in natural pH, surface tension, critical micelle concentration and content of functional groups. After a single washing, TA （pH 3.44） more efficiently mobilized As than SAP （pH 5.44）. When both biosurfactants were used at the same pH （SAP adjusted to 3.44）, arsenic mobilization was improved by triple washing. The process efficiency for TA and SAP was similar, and depending on the soil sample, ranged between 50%-64%. Arsenic mobilization by TA and SAP resulted mainly from decomposition of Fe arsenates, followed by Fe3＋ complexation with biosurfactants. Arsenic was efficiently released from reducible and partially from residual fractions. In all soils, As（V） was almost completely removed, whereas content of As（III） was decreased by 37%-73%. SAP and TA might be used potentially to remove As from contaminated soils.     

Is body size of the water frog Rana esculenta complex responding to climate change?

Recent studies on climate responses in ectothermic (cold-blooded) vertebrates have been few in number and focussed on phenology rather than morphology. According to Bergmann’s rule, endothermic (warm-blooded) vertebrates from cooler climates tend to be larger than congeners from warmer regions. Although amphibians are ectothermic vertebrates, weather and climatic conditions may also impact on their morphology, and thereby affect their survival rates and population dynamics. In this paper, we show, in a unique long-term study during the period 1963–2003 in an agricultural landscape in western Poland, that the body length of two water frog parental species (males of both Rana ridibunda and R. lessonae) increased significantly. However, their hybridogenetic hybrid R. esculenta did not show similar changes. A significant relationship with a large-scale climatic factor, the winter North Atlantic Oscillation index, was found positive for R. ridibunda males and R. lessonae females, and negative for R. esculenta females. Our findings, the first for amphibians, are consistent with other studies reporting that recent climate change has affected the morphology of animals. However, we also show that changes in amphibian phenotype linked to climate may vary independently between (even very similar) species.