Environmental factors in coal liquefaction plant design /

Presented at EPA Symposium on Environmental Aspects of Fuel Conversion Technology, May 14, 1974.

Opções reais em projetos de investimentos: o caso de uma planta de liquefação de gás natural com flexibilidade de troca de mercado e de troca de produto

O objetivo deste trabalho é revisar os principais aspectos teóricos para a aplicação de Opções Reais em avaliação de projetos de investimento e analisar, sob esta metodologia, um caso real de projeto para investir na construção de uma Planta de Liquefação de gás natural. O estudo do caso real considerou a Opção de Troca de Mercado, ao avaliar a possibilidade de colocação de cargas spot de GNL em diferentes mercados internacionais e a Opção de Troca de Produto, devido à flexibilidade gerencial de não liquefazer o gás natural, deixando de comercializar GNL no mercado internacional e passando a vender gás natural seco no mercado doméstico. Para a valoração das Opções Reais foi verificado, através da série histórica dos preços de gás natural, que o Movimento Geométrico Browniano não é rejeitado e foram utilizadas simulações de Monte Carlo do processo estocástico neutro ao risco dos preços. O valor da Opção de Troca de Mercado fez o projeto estudado mais que dobrar de valor, sendo reduzido com o aumento da correlação dos preços. Por outro lado, o valor da Opção de Troca de Produto é menos relevante, mas também pode atingir valores significativos com o incremento de sua volatilidade. Ao combinar as duas opções simultaneamente, foi verificado que as mesmas não são diretamente aditivas e que o efeito do incremento da correlação dos preços, ao contrário do que ocorre na Opção de Troca de Mercado, é inverso na Opção de Troca de Produto, ou seja, o derivativo aumenta de valor com uma maior correlação, apesar do valor total das opções integradas diminuir.

Planta de licuación de 1 MTPA LNG Prico en Texas, EEUU

En este proyecto se ha realizado el dimensionamiento de los equipos básicos de una planta de licuación de gas natural cuya localización es Texas, EEUU. La capacidad de la planta es de 1 MTPA y funciona mediante un proceso de licuefacción de licencia Prico. Su objetivo fundamental es servir de apoyo en las puntas de consumo de gas natural (el cual varía considerablemente según la época del año) mediante reinyección del producto en los gaseoductos en los momentos de mayor demanda o incluso mediante su transporte en camiones cisterna. El proyecto ha comprendido el análisis del proceso Prico con su diagrama de flujo, el dimensionamiento de los intercambiadores de calor (carcasa y tubos y plate-fin), selección de los equipos rotativos, simulación del proceso y dimensionamiento de tuberías, así como un pequeño estudio económico. Abstract In this project, sizing of main equipment of a natural gas liquefaction plant has been developed. The plant is located in Texas, EEUU. Plant capacity is 1 MTPA and is designed to produce LNG by using a Prico liquefaction process. The main objective of the designed plant is to support the peaks of consumption of natural gas (which varies considerably along the year) by liquefying, storing and reinjecting the natural gas in the pipelines or even using tanker trucks to take LNG to consumers. The project includes the analysis of the Prico process flow diagram, sizing of the heat exchangers (shell & tube and plate-fin), selection of rotatory equipment, process simulation and pipe sizing, and a viability analysis.

Desenvolvimento de um método para diagnose de falhas na operação de navios transportadores de gás natural liquefeito através de redes bayesianas.

O Gás Natural Liquefeito (GNL) tem, aos poucos, se tornado uma importante opção para a diversificação da matriz energética brasileira. Os navios metaneiros são os responsáveis pelo transporte do GNL desde as plantas de liquefação até as de regaseificação. Dada a importância, bem como a periculosidade, das operações de transporte e de carga e descarga de navios metaneiros, torna-se necessário não só um bom plano de manutenção como também um sistema de detecção de falhas que podem ocorrer durante estes processos. Este trabalho apresenta um método de diagnose de falhas para a operação de carga e descarga de navios transportadores de GNL através da utilização de Redes Bayesianas em conjunto com técnicas de análise de confiabilidade, como a Análise de Modos e Efeitos de Falhas (FMEA) e a Análise de Árvores de Falhas (FTA). O método proposto indica, através da leitura de sensores presentes no sistema de carga e descarga, quais os componentes que mais provavelmente estão em falha. O método fornece uma abordagem bem estruturada para a construção das Redes Bayesianas utilizadas na diagnose de falhas do sistema.

Seismic microzonation of a nuclear power plant site with detailed geotechnical, geophysical and site effect studies

This paper highlights the seismic microzonation carried out for a nuclear power plant site. Nuclear power plants are considered to be one of the most important and critical structures designed to withstand all natural disasters. Seismic microzonation is a process of demarcating a region into individual areas having different levels of various seismic hazards. This will help in identifying regions having high seismic hazard which is vital for engineering design and land-use planning. The main objective of this paper is to carry out the seismic microzonation of a nuclear power plant site situated in the east coast of South India, based on the spatial distribution of the hazard index value. The hazard index represents the consolidated effect of all major earthquake hazards and hazard influencing parameters. The present work will provide new directions for assessing the seismic hazards of new power plant sites in the country. Major seismic hazards considered for the evaluation of the hazard index are (1) intensity of ground shaking at bedrock, (2) site amplification, (3) liquefaction potential and (4) the predominant frequency of the earthquake motion at the surface. The intensity of ground shaking in terms of peak horizontal acceleration (PHA) was estimated for the study area using both deterministic and probabilistic approaches with logic tree methodology. The site characterization of the study area has been carried out using the multichannel analysis of surface waves test and available borehole data. One-dimensional ground response analysis was carried out at major locations within the study area for evaluating PHA and spectral accelerations at the ground surface. Based on the standard penetration test data, deterministic as well as probabilistic liquefaction hazard analysis has been carried out for the entire study area. Finally, all the major earthquake hazards estimated above, and other significant parameters representing local geology were integrated using the analytic hierarchy process and hazard index map for the study area was prepared. Maps showing the spatial variation of seismic hazards (intensity of ground shaking, liquefaction potential and predominant frequency) and hazard index are presented in this work.

Sexual selection in a tropical fruit fly : role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field-cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME-fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME-fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field-cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant-derived chemicals.

Influence of host plant structure and microclimate on the abundance and behaviour of Tephritid fly

Microclimate and host plant architecture significantly influence the abundance and behavior of insects. However, most research in this field has focused at the invertebrate assemblage level, with few studies at the single-species level. Using wild Solanum mauritianum plants, we evaluated the influence of plant structure (number of leaves and branches and height of plant) and microclimate (temperature, relative humidity, and light intensity) on the abundance and behavior of a single insect species, the monophagous tephritid fly Bactrocera cacuminata (Hering). Abundance and oviposition behavior were signficantly influenced by the host structure (density of foliage) and associated microclimate. Resting behavior of both sexes was influenced positively by foliage density, while temperature positively influenced the numbers of resting females. The number of ovipositing females was positively influenced by temperature and negatively by relative humidity. Feeding behavior was rare on the host plant, as was mating. The relatively low explanatory power of the measured variables suggests that, in addition to host plant architecture and associated microclimate, other cues (e.g., olfactory or visual) could affect visitation and use of the larval host plant by adult fruit flies. For 12 plants observed at dusk (the time of fly mating), mating pairs were observed on only one tree. Principal component analyses of the plant and microclimate factors associated with these plants revealed that the plant on which mating was observed had specific characteristics (intermediate light intensity, greater height, and greater quantity of fruit) that may have influenced its selection as a mating site.

Somatic embryogenesis, organogenesis and plant regeneration in taro (Colocasia esculenta var. esculenta)

Callus was initiated in three different ‘‘esculenta’’ taro cultivars by culturing corm slices in the dark on half-strength MS medium supplemented with 2.0 mg/l 2,4- dichlorophenoxyacetic acid (2,4-D) for 20 days followed by subculture of all corm slices to half-strength MS medium containing 1.0 mg/l thidiazuron (TDZ). Depending on the cultivar, 20–30% of corm slices produced compact, yellow, nodular callus on media containing TDZ. Histological studies revealed the presence of typical embryogenic cells which were small, isodiametric with dense cytoplasms. Somatic embryos formed when callus was transferred to hormone-free medium and *72% of the embryos germinated into plantlets on this medium. Simultaneous formation of roots and shoots during germination, and the presence of shoot and root poles revealed by histology, confirmed that these structures were true somatic embryos. Plants derived from somatic embryos appeared phenotypically normal following 2 months growth in a glasshouse. This method is a significant advance on those previously reported for the esculenta cultivars of taro due to its efficiency and reproducibility.

Initiation of embryogenic cell suspensions of taro (Colocasia esculenta var. esculenta) and plant regeneration

Embryogenic callus was initiated by culturing in vitro taro corm slices on agar-solidified half-strength MS medium containing 2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) for 20 days followed by transfer to 1.0 mg/L thidiazuron (TDZ). Callus was subsequently proliferated on solid medium containing 1.0 mg/L TDZ, 0.5 mg/L 2,4- D and 800 mg/L glutamine before transfer to liquid medium containing the same components but with reduced glutamine (100 mg/L). After 3 months in liquid culture on an orbital shaker, cytoplasmically dense cell aggregates began to form. Somatic embryogenesis was induced by plating suspension cells onto solid media containing reduced levels of hormones (0.1 mg/L TDZ, 0.05 mg/L 2,4-D), high concentrations of sucrose (40–50 g/L) and biotin (1.0 mg/L). Embryo maturation and germination was then induced on media containing 0.05 mg/L benzyladenine (BA) and 0.1 mg/L indole-3-acetic acid (IAA). Histological studies of the developing embryos revealed the presence of typical shoot and root poles suggesting that these structures were true somatic embryos. The rate of somatic embryos formation was 500–3,000 per mL settledcell volume while approximately 60% of the embryos regenerated into plants.

A cost-based optimization of a fiberboard pressing plant using Monte-Carlo simulation (a reliability program)

In this research the reliability and availability of fiberboard pressing plant is assessed and a cost-based optimization of the system using the Monte- Carlo simulation method is performed. The woodchip and pulp or engineered wood industry in Australia and around the world is a lucrative industry. One such industry is hardboard. The pressing system is the main system, as it converts the wet pulp to fiberboard. The assessment identified the pressing system has the highest downtime throughout the plant plus it represents the bottleneck in the process. A survey in the late nineties revealed there are over one thousand plants around the world, with the pressing system being a common system among these plants. No work has been done to assess or estimate the reliability of such a pressing system; therefore this assessment can be used for assessing any plant of this type.