• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 254
  • 215
  • 59
  • 29
  • 16
  • 11
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 694
  • 192
  • 92
  • 89
  • 79
  • 74
  • 62
  • 52
  • 51
  • 48
  • 47
  • 44
  • 43
  • 42
  • 42
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Studies in the design and control of coupled distillation columns

Levien, Keith Lester. January 1985 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1985. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 453-462).
32

Plate efficiencies in fractional distillation

Beyer, Gerhard H. January 1949 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [79]-80).
33

Quantitative comparison of a reactive distillation column with a conventional multi-unit process /

Kaymak, Devrim B., January 2005 (has links)
Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references (leaves 218-227).
34

Engineering and economic evaluation of solar distillation for small communities.

Lawand, T. A., 1935- January 1968 (has links)
No description available.
35

Experimental and analytical studies of hydrocarbon yields under dry-, steam-, and steam-with-propane distillation

Jaiswal, Namit 17 September 2007 (has links)
Simulation study has shown oil production is accelerated when propane is used as an additive during steam injection. To better understand this phenomenon, distillation experiments were performed using San Ardo crude oil (12oAPI). For comparison purposes, three distillation processes were investigated: dry-, steam-, and steam-propanedistillation, the latter at the propane-to-steam mass ratio of 0.05 at steam injection rate 0.5 g/min. Two sets of the distillation experiments were carried out. In the first set of experiments, the distillation temperatures ranged from 115ºC to 300ºC. Distillation pressures ranged from 0 psig to 998 psig for steam- and steam-propane distillation. The temperature-pressure combination used represented 15ºC superheated steam conditions. In the second set of experiments, the distillation temperatures ranged from 220oC to 300oC at 260 psig. The temperature pressure combination used represented field conditions for crude oil. For both conditions, the cell was kept at each temperature plateau (cut) until no increase occurs in distillation yields. Distillation yields were collected at each cut, and the volume and weight of water and hydrocarbon measured. Based on these experiments, a thermodynamic modeling framework was developed that describes distillation effect and oil production for steam distillation experiments. The model is based on composition of crude oil, molecular weight of heavy fraction. The analytical model results are compared against the experimental data for synthetic crude and crude oil to verify the validity of the model. Main results of the study may be summarized as follows. The yields for steam distillation for saturated conditions of Tsat+15 o C and Psat is 10 % and with addition of 5% of propane to steam no significant increase occurs in distillation yields. The yields for steam distillation for field conditions of 260 psig and temperature range (220 ~300oC) is 18 % and with addition of 5% of propane to steam no significant increase in distillation yields. The results indicate that propane has minimal distillation effect on the heavy oil. This occurs possibly because of lesser amount of light fractions in the heavy oil that enhance the separation of components in the oil caused by the concentration gradient.
36

Modeling and control of packed reactive distillation columns

Peng, Jianjun 13 July 2011 (has links)
Not available / text
37

Micro-distillation studies in continuous flow analysis /

McLeod, Stanley. Unknown Date (has links)
Thesis (PhD)--University of South Australia, 1993
38

Simulation and control of reactive distillation.

Sneesby, Martin G. January 1998 (has links)
Reactive distillation has enormous potential for the economical synthesis of tertiary ethers. Methyl tert-butyl ether (MTBE) has been commercially produced with this technology since the early 1980s and it appears that the process also has application for Ethyl tert-butyl ether (ETBE) and other ethers. However, the combination of reaction and distillation in a single unit operation produces a process complexity that inhibits expeditious design and tight control, and presents a technology risk for potential developers. This particularly applies to hybrid reactive distillation where both reactive and non-reactive column sections are employed.The steady state simulation of a series of reactive distillation columns and processes for the production of ETBE and MTBE illuminated a number of important issues related to the optimal design techniques. Many of these issues are peculiar to reactive distillation and would not reasonably be anticipated without a priori knowledge of the phenomena involved. For example, the addition of theoretical equilibrium stages and an increase in the reflux ratio do not always have a directionally equivalent effect. The trade-off between energy consumption and capital cost which is the basis for most distillation designs cannot always be applied to reactive distillation. Importantly, the use of standard modelling techniques for equilibrium processes was also validated for reactive distillation design.The use of residue curve diagrams and reactive residue curve diagrams for the design of reactive distillation processes was investigated and shown to provide useful information regarding the feasibility of reaction-separations. Combined with simulation tools (e.g. Pro/II and SpeedUp), these techniques form the basis of a proposed design strategy for hybrid reactive distillation. It is important to apply these design tools appropriately and to ++ / select the correct process for a given application. The optimal design must also consider economics and the relative values of products, reactants and energy. These issues were studied with respect to ETBE production for gasoline oxygenation.The complexity of hybrid reactive distillation not only presents design challenges but potentially makes the process more difficult to control. Dynamic simulations of ETBE and MTBE reactive distillation processes were used to explore some unusual dynamic phenomena and to elucidate the process non-linearity and bidirectionality of reactive distillation. The presence of multiple steady states for some reactive distillation columns has been documented previously but the analysis of this behaviour has been incomplete and somewhat flawed. It was shown that the distinction between molar inputs and physically realisable mass or volumetric inputs is crucial and that multiplicity could be present in one case and not in the other. Multiplicity that is only observed with molar inputs (relatively common) was termed pseudo-multiplicity. Pseudo-multiplicity has few implications for the operation and control of practical reactive distillation processes although most literature examples of multiple steady states fall into this category. Four distinct causes of output multiplicity were identified including one new cause, reaction hysteresis, which is only applicable to hybrid reactive distillation. It was shown, using dynamic simulations, that transitions between parallel steady states are possible for a range of physically realisable and practical disturbances. This contrasts with other work in the area, which examines only unrealisable events and control schemes.An extensive analysis of reactive distillation control was also undertaken with respect to ETBE and MTBE hybrid columns. Manual (open-loop) control was shown to be impractical due to ++ / the need to sustain the operating conditions at close to the optimal values in order to produce acceptable process performance. One-point composition control was found to be relatively easy to implement and effective with either an energy-balance or a material-balance control scheme provided only one steady state was present. Where multiple steady states exist, there are restrictions on the feasible control structures due to unavoidable instability in the inventory controllers. For example, if multiple steady states exist for the one value of the reboiler duty, only the bottoms product draw rate can be used to control the reboiler sump level. Thus, a material-balance control structure that uses the reboiler duty to control the sump level cannot be implemented in practice. Two-point control was also investigated and found to effectively prevent transitions between parallel steady states. Although more complex and difficult to implement than one-point control, a two-point scheme could be used successfully to control both the product composition and the reactant conversion and this could be desirable in some cases.A reactive distillation pilot plant was designed and operated for ETBE synthesis from ethanol and a locally available refinery hydrocarbon stream. The design of the pilot plant was based on simulation studies and the objective of operating in the industrially significant ranges of product purity and isobutene conversion. A fully automatic control system was designed and installed on the pilot plant to permit precise control of the manipulated variables and the framework to implement a range of control structures and schemes.Keywords: reactive distillation; process simulation; process design; process control; dynamic simulation; multiplicity; bidirectionality; distillation control; inferential control; pilot plant design and operation.
39

Fundamental model for the prediction of distillation sieve tray efficiency : hydrocarbon and aqueous systems /

García-Martínez, José Antonio, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 318-330). Available also in a digital version from Dissertation Abstracts.
40

Estudo da Correlação de Resultados da Destilação de Petróleo Pelas Normas ASTM D2892 e D5236 Com a Destilação Simulada pela ASTM D7169

QUEIROZ, L. O. S. 14 June 2017 (has links)
Made available in DSpace on 2018-08-01T21:36:54Z (GMT). No. of bitstreams: 1 tese_11042_Dissertação Lucas Queiroz - FINAL APROVADA.pdf: 801845 bytes, checksum: c02d945e52f528faf6319ad6dda19507 (MD5) Previous issue date: 2017-06-14 / A Destilação é um dos processos mais importantes na caracterização do petróleo pois o separa em diferentes frações. O conhecimento da distribuição dos pontos de ebulição dos componentes do petróleo e da proporção de seus cortes é essencial para o controle e logística desse processo durante o refino, além de garantir sua qualidade e possibilitar a valoração do óleo cru. Os métodos laboratoriais mais utilizados atualmente para este fim são as ASTM D2892 (destilação atmosférica: atinge temperatura máxima de 400 ºC) e ASTM D5236 (destilação a vácuo: utiliza pressões reduzidas para destilar o resíduo atmosférico para evitar o craqueamento das moléculas). A curva PEV (curva de pontos de ebulição verdadeiros - resultado laboratorial da destilação física) é obtida através da soma dos resultados das destilações atmosférica e a vácuo. Entretanto, esses processos demandam grandes quantidades de amostra (de 5 a 40 L) e tempo (3 a 4 dias). A Destilação Simulada por cromatografia gasosa (SIMDIS, do inglês Simulated Distillation) se apresenta como uma interessante solução para contornar esses problemas. A amostra é volatilizada e a separação de seus compostos ocorre no interior de uma coluna cromatográfica sob uma variação de temperatura controlada, produzindo um cromatograma e uma curva PEV. Neste trabalho, 98 amostras de petróleo nacionais e internacionais foram analisadas e seus dados foram correlacionados em diferentes etapas. Inicialmente, cada amostra foi analisada utilizando o método ASTM D7169 (SIMDIS) no laboratório de cromatografia do LabPetro na Universidade Federal do Espírito Santo (UFES). Essa etapa gerou 4 replicatas.para cada amostra, as quais foram submetidas a uma avaliação de similaridade para determinar qual apresentou o melhor resultado. Os dados da melhor replicata foram correlacionados com os obtidos no Centro de Pesquisas e Desenvolvimento Leopoldo Américo Miguez de Mello (CENPES-Petrobras). A primeira comparação foi uma avaliação de similaridade realizada entre os resultados de SIMDIS dos dois laboratórios, realizada para 44 amostras (amostras cujos resultados de SIMDIS foram disponibilizados pelo CENPES). Em seguida, os dados de SIMDIS obtidos na UFES foram correlacionados com os da destilação convencional do CENPES-Petrobras. A correlação dos resultados se deu através da comparação dos valores de ponto de ebulição a cada 5% de recuperação em massa. A fim de obter esses valores para as duas técnicas, foi feito um ajuste polinomial de quinta ordem. Por fim, foi aplicado um teste de Viés para para avaliar a correlação dos dados. A avaliação final dos resultados evidenciou uma boa similaridade entre os resultados da destilação convencional e SIMDIS. A correlação para 13 petróleos (de um total de 15) obteve bons, não exibindo erros sistemáticos significativos.

Page generated in 0.2028 seconds