Reaction engineering

Formation of methyl ethyl ketazine is a distinct case of homogeneous catalyzed gas–liquid–liquid reactions. Kinetics studies of methyl ethyl ketazine formation has been carried out in a semi-batch reactor. The effects of temperature and catalyst concentration on the percentage yield of ketazine have been studied extensively. The yield of ketazine is found to increase with increase in temperature and then levels off. Increase in catalyst concentration favours the formation of ketazine. The conversion of peroxide is found to increase with increase in temperature thus indicating that chemical reaction is rate-limiting step in the system. The desired temperature for carrying out the reaction is found to be 60°C and the required catalyst to peroxide ratio is 2.5. The activation energy for the reaction is 24.5 kJ/mol.La formation de méthyléthylkétazine est un cas distinct de réactions gaz-liquide-liquide catalysées homogènes. Des études cinétiques de la formation de méthyléthylkétazine ont été menées dans un réacteur semi-continu. Les effets de la température et de la concentration de catalyseur ont été étudiés de manière approfondie. On a trouvé que le rendement de kétazine augmentait avec l'augmentation de la température pour s'établir ensuite à un niveau constant. Une augmentation de la concentration de catalyseur favorise la formation de kétazine. On a trouvé que la conversion du peroxyde augmentait avec l'augmentation de la température, indiquant ainsi que la réaction chimique est une étape limitante de la cinétique pour le système. On a trouvé que la bonne température pour mener la réaction était de 60°C et le rapport catalyseur-peroxyde requis de 2,5. L'énergie d'activation pour la réaction est de 24,5 kJ/mol.

Experiments have been performed on a Homogeneous Charge Compression Ignition Engine (HCCI) fuelled with natural gas. The in-cylinder pressure has been measured for different engine speeds and fuel-air ratios. Numerical simulations of the ignition process in the engine have been carried out using a detailed reaction mechanism for butane and lower alkanes. The effects of engine speed an fuel-air ratio on autoignition have been calculated and compared with measurements. In addition, calculations have been made of the ignition delay time sensitivity to initial pressure, initial temperature, and quality of gas fuel. Excellent agreement with single-cycle measurements is obtained for the calculated temperature and pressure profiles. The single-cycle temperature simulations show good agreement with 100 cycle-averaged measurements as well, but cycle-to cycle variations flatten out the averaged profiles, and the need for a PDF-based approach to achieve perfection is evident. Furthermore, it was found that the autoignition process in an HCCI engine is extremely sensitive to variations in initial temperature, whereas changes in pressure, fuel-air ratio and engine speed affects the ignition timing to a much lesser extent.

"The purpose of this checklist is to identify the stages and potential problems associated with the scale up of fixed bed reactors from the drawing board to the full scale plant, and to determine how they should be checked.

The checking can be done using various methods. These are:

•  Literature data.

•  Lab testing.

•  Calculation.

•  Modeling.

•  Semi-tech testing.

•  Piloting or Side-stream testing.


Identifying the stages that need to be addressed for a particular catalyst/reactor development will help in estimating the time needed for the development of the reactor.
"
#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;

This guide covers the reaction kinetics and diffusional aspects of solid catalyzed reactions. It does not deal with either the fluid dynamics or the mechanical design of reactors for solid Catalyzed reactions.

#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;

Gravity drainage systems occur frequently on chemical plants. Typical examples are:

(a) the condensate off-take from a condenser;

(b) the liquid off-take from the base of an absorption column;

(c) the emergency overflow from an atmospheric pressure storage tank.

Gas entrained in a liquid flowing by gravity from a vessel will reduce the volume of liquid flowing through the pipe and could cause surging flows.

The objective of this study was to maximize the conversion of saponification reaction in a continuous stirred tank reactor (CSTR). Full two-level factorial design and response surface methodology (RSM) were used t o d e t e r m i n e t h e optimum values of significant factors. The effect of five factors (sodium hydroxide and ethylacetate concentrations, feed ratio, agitation rate and temperature) was studied on the fractional conversion of sodium hydroxide (XNaOH). As a result of screening experiments, two factors (sodium hydroxide and ethylacetate concentrations) and their combined effect were found to be significant operating parameters for the saponification reaction in continuous stirred tank reactor (CSTR). The optimum values of these significant factors were also determined using response surface methodology (RSM). For maximum conversion of sodium hydroxide (XNaOH), i.e., 96.71%, the optimum values of sodium hydroxide and ethylacetate concentrations were found to be 0.01mol/L...

This paper presents a simple method for solving multireaction chemical equilibrium problems via Gibbs Minimization through the use of a stochastic global optimizer. The method is explained at the level of upper-undergraduate chemistry or chemical engineering students. Its matlab code is also presented and explained. Four examples with varying difficulties illustrate the versatility and robustness of the method, which is simple, general, and scalable and can be easily extended to simultaneous chemical and phase equilibrium problems.

The open-source release of self-replicating rapid prototypers (RepRaps) has created a rich opportunity for low-cost distributed digital fabrication of complex 3-D objects such as scientific equipment. For example, 3-D printable reactionware devices offer the opportunity to combine open hardware microfluidic handling with lab-on-a-chip reactionware to radically reduce costs and increase the number and complexity of microfluidic applications. To further drive down the cost while improving the performance of lab-on-a-chip paper-based microfluidic prototyping, this study reports on the development of a RepRap upgrade capable of converting a Prusa Mendel RepRap into a wax 3-D printer for paper-based microfluidic applications. An open-source hardware approach is used to demonstrate a 3-D printable upgrade for the 3-D printer, which combines a heated syringe pump with the RepRap/Arduino 3-D control. The bill of materials, designs, basic assembly, and use instructions are provided, along with a completely free and open-source software tool chain. The open-source hardware device described here accelerates the potential of the nascent field of electrochemical detection combined with paper-based microfluidics by dropping the marginal cost of prototyping to nearly zero while accelerating the turnover between paper-based microfluidic designs.

This document is one of a series on fluid flow produced by GBH Enterprises.

If a rapid change is made to the flowrate of a liquid in a piping system, for example by the operation of a valve, a transient pressure change will be propagated through the system. This transient pressure may be significantly greater than either the initial pressure or the final steady state pressure which the system reaches. This may cause damage to the piping system; either by exceeding the design pressure of the piping system with consequent risk of rupture, or by producing out of balance forces which are greater than can be sustained by the pipe supports. The phenomenon known as 'water hammer' is a special case of 'pressure surge'.

The objective of this study was to maximize the conversion of saponification reaction in a continuous stirred tank reactor (CSTR). Full two-level factorial design and response surface methodology (RSM) were used t o d e t e r m i n e t h e optimum values of significant factors. The effect of five factors (sodium hydroxide and ethylacetate concentrations, feed ratio, agitation rate and temperature) was studied on the fractional conversion of sodium hydroxide (X NaOH). As a result of screening experiments, two factors (sodium hydroxide and ethylacetate concentrations) and their combined effect were found to be significant operating parameters for the saponification reaction in continuous stirred tank reactor (CSTR). The optimum values of these significant factors were also determined using response surface methodology (RSM). For maximum conversion of sodium hydroxide (X NaOH), i.e., 96.71%, the optimum values of sodium hydroxide and ethylacetate concentrations were found to be 0.01mol/L and 0.1 mol/L, respectively. Acorrelation was developed to show the relationship between different significant factors and response. The validity of the model was checked using analysis of variance (ANOVA). The experimental results are believed to be within reasonable accuracy and may be applicable for the improvement of such processes on industrial scale.

Abstract: Problem statement: The effect of different temperatures and acid concentrations on the
corrosion of low carbon steel in hydrochloric acid were addressed in this study. Approach: The
effect of temperature was explained by application of Arrhenius equation and transition state theory,
while the acid concentration effect was explained using reaction kinetic equations. The combined
effect of temperature and acid concentration then modeled using a nonlinear regression method.
Results: A detail of thermodynamic parameters of activation (E,
H* and
S*) and kinetic studies
for the corrosion reaction were obtained. Nonlinear corrosion rates as a function of temperature and
acid concentration equation were estimated with a good prediction corrosion rates values.
Conclusion: The values of activation energy E and enthalpy of activation
H* decrease with
increase in acid concentration indicating the increasing in reaction rate. Entropy of activation
S*
tend to lower values with increasing in acid concentration which indicated that the activated
complex was more orderly relative to the initial state. The corrosion reaction was approximately firs
order reaction. The observed corrosion rate values from the experimental data were in a good
agreement with that predicated by the mathematical equation.

Boiler Water Circulation Pumps

1 SCOPE

2 CHOICE OF TYPE AND NUMBER OF PUMPS

2.1 Need for Continuous Flow

2.2 Pump Reliability

3 CHOICE OF DRIVER

4 DUTY CALCULATIONS

5  CHOICE OF SEAL

5.1 Mechanical Seals

5.2 Soft-packed Glands

5.3 Construction Features

5.4 Guarding

6  CONSTRUCTION FEATURES

6.1 Vertical Glandless Wet-stator Motor Pumps

7 LAYOUT

7.1 Non-return Valves

7.2 Reducers at Pump Connections

7.3 Glandless Pumps for System Pressures
Exceeding 60 bar abs

7.4 Access round Glandless Pumps

7.5 Cooling Water Supply

8  RECOMMENDED LINE DIAGRAMS

8.1 Horizontal Pumps in Category 1

8.2 Vertical Wet-stator Motor Pumps in Category


APPENDICES

A PROPERTIES OF WATER AT THE SATURATION LINE

B ANNEX TO API 610, 6TH EDITION 1981:
VERTICAL GLANDLESS WET-STATOR MOTOR PUMPS

C ANNEX TO API 610, 6TH EDITION 1981:
HORIZONTAL BACK PULL-OUT PUMPS FOR BOILER
WATER CIRCULATION DUTY

FIGURES

3.1 NPSH CORRECTION FOR WATER

3.2 VELOCITY OF SOUND IN WATER AT 50 BAR
(NO BUBBLES)

3.3 VELOCITY OF SOUND IN WATER AT 50 BAR
(WITH 3% VAPOR CONTENT)

8.1 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - CATEGORY 1

8.2 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - SOFT PACKED GLAND INSTALLATION

8.3 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - MECHANICAL SEAL INSTALLATION

8.4 RECOMMENDED LINE DIAGRAM VERTICAL WET STATOR PUMPS - CATEGORY 2

BIBLIOGRAPHY

This guide provides a basic introduction to the theory of gas-liquid reactions. It deals with the microscopic scale phenomena of absorption, mass transfer and chemical reaction and indicates how these are integrated with fluid flow and heat transfer to provide predictions of reactor performance. Some attention is given to the experimental determination of the relevant physicochemical parameters. Finally, guidance is offered on the selection of appropriate gas-liquid reactors for a given system.

#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;

This work concentrates on automatic procedures for simplifying chemical models for realistic fuels using skeletal mechanism construction and Quasi Steady-State Approximation (QSSA) applied to detailed reaction mechanisms. To automate the selection of species for removal or approximation, different indices for species ranking have thus been proposed. Reaction flow rates are combined with sensitivity information for targeting a certain quantity, and used to determine a level of redundancy for automatic skeletal mechanism construction by exclusion of redundant species. For QSSA reduction, a measure of species lifetime can be used for species ranking as-is, weighted by concentrations or molecular transport timescales, and/or combined with species sensitivity. Maximum values of the indices are accumulated over ranges of parameters, (e.g. fuel-air ratio and octane number), and species with low accumulated index values are selected for removal or steady-state approximation. In the case of QSSA, a model with a certain degree of reduction is automatically implemented as FORTRAN code by setting a certain index limit. The code calculates source terms of explicitly handled species from reaction rates and the steady-state concentrations by internal iteration. Homogeneous-reactor and one-dimensional laminar-flame models were used as test cases. A staged combustor fuelled by ethylene with monomethylamine addition is modelled by two homogeneous reactors in sequence, i.e. a PSR (Perfectly Stirred Reactor) followed by a PFR (Plug Flow Reactor). A modified PFR model was applied for simulation of a Homogeneous Charge Compression Ignition (HCCI) engine fuelled with four-component natural gas, whereas a two-zone model was required for a knocking Spark Ignition (SI) engine powered by Primary Reference Fuel (PRF). Finally, a laminar one-dimensional model was used to simulate premixed flames burning methane and an aeroturbine kerosene surrogate consisting of n-decane and toluene. In general, detailed calculations of temperature, pressure, concentration and flame velocity show excellent agreement with measurements. Skeletal mechanisms for PRF were constructed for the SI engine case, reproducing autoignition well on removal of reactions pertaining to 15% of the species. QSSA reduction was tested on the staged combustor and the engines, using pure and weighted lifetime indices. Monitoring NO concentrations in the staged combustor and ignition timing in the engines, good reproduction is possible while approximating about 70% of the species. However, some species have to be manually retained for accuracy and numerical stability. For improved ranking, sensitivity was added to the index applied to the premixed flames, in addition to necessary molecular transport information. The maximum atomic mass fraction occupied by a certain molecular species was also constrained to limit the mass and energy deficiency caused by QSSA. For methane, the laminar flame velocities as well as concentration profiles are well predicted by the most strongly reduced mechanism with five global reaction steps. For the kerosene surrogate mechanism, QSSA involving 50% of the species was successfully attempted.

"When the catalyst chemistry of a new fixed feed chemical reaction has been developed, decisions need to be made about the catalyst design. The issues that need to be decided are:

(a) The catalyst particle size.

(b) The catalyst shape to give a reasonable optimum pressure drop in the catalyst bed.

(c) The catalyst particle density to make the catalyst particles reasonably effective.

These issues are closely related to the reactor shape and the cost of pressure drop.

This Process Engineering Guide provides some explanation of these issues and equations by which the key parameters can be determined.
"

#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;

Hydrogenation of D-glucose in the presence of Raney nickel as a catalyst was
employed for the preparation of D-sorbitol. The effects of the reaction time (15-90 min),
reaction temperature (10-60 oC), and catalyst to D-glucose ratio (5-15 wt %) on the yield of
D-sorbitol were studied. The experimental design of Box-Wilson method was adopted to
find a useful relationship between the effecting variables and the D-sorbitol yield. The
experimental data collected by this design was successively fitted to a second order
polynomial mathematical model. The analysis of variance shows that the catalyst to Dglucose
ratio had the greatest effect on the yield of D-sorbitol among other variables. An
optimum operating conditions of 67 min reaction time, 46 °C reaction temperature, and
14.5 % catalyst to D-glucose ratio gave 87.15 % D-sorbitol yield, 6.51 % D-mannitol yield,
and 95.93 % D-glucose conversion. D-sorbitol of purity 99.8 % was obtained after its
separation from D-mannitol, the byproduct of the hydrogenation process, using the
fractional crystallization method.

Algunas aleaciones Fe-C presentan una excelente combinación de tenacidad y resistencia mecánica, asociada a los productos de la reacción bainítica, que las hace útiles en la fabricación de componentes de máquinas sometidos a altos esfuerzos. Sin embargo, en nuestro medio el conocimiento de esta transformación es reducido; esto hace difícil la competitividad del sector metalmecánica en la economía globalizada. En este trabajo se hace un compendio de los conceptos básicos de la reacción bainítica, que va más allá de los textos clásicos de transformaciones de fases metálicas y considerando los últimos avances que se han realizado en su estudio. Además, se analizan los factores más importantes de la bainita tanto en aceros como en fundiciones nodulares. Se discuten los mecanismos de transformación, la cinética de reacción, las características microestructurales y las propiedades mecánicas. El objetivo del trabajo es difundir las nociones y técnicas requeridas para la implementación de esta transformación de fase, buscando promover el desarrollo de productos bainíticos.

PACS: 81.05.Bx

"This guide sets out the key steps in the design of gas or liquid phase homogeneous reactors and suggests appropriate types of reactor according to the required residence time, flow pattern and heat transfer duty.

A liquid phase reactor with a vapor product is covered only if the vapor removal rate does not affect the overall rate. If it does, consider thin-film reactors.
"
#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;

The need for reliable physical property data has long been recognized. In pre-computer days, this was in the form of tabulations and graphs. Computers demanded that the form in which the data were supplied had to be adapted. This required not only accuracy, but robustness and ease of machine evaluation.

#Fundamentals; #New Preparations and New Active Materials; #Synthesis and Characterization of Catalysts; #Characterization of Catalyst in its Working State; #Catalyst Deactivation; #Reaction Kinetics; #Reactor Modeling; #Reactor Design, Control and Optimization; #Novel Reactors and Process Developments;