Dynamic adsorption of SO2 on zeolite molecular sieves

Sulfur dioxide is one of the major pollutants resulting from fuel combustion. Numerous dry, semi-dry and wet processes have been developed for pollution control of sulfur dioxide. Solid carbonates, natural and synthetic zeolites, ion exchange resins and carbon based sorbents are the most commonly used dry sorbents for sulfur dioxide removal. In this study, measurements of the adsorption properties of sulfur dioxide on zeolites were investigated. The adsorbents used in this work are 5A, 4A and AW300 type molecular sieve zeolites. Adsorption equilibrium parameters were determined from the pulse Chromatographic response to injections of low concentrations of sulfur dioxide. The method of moments were used to evaluate the adsorption equilibrium parameters from pulse Chromatographic experiments. Data, such as adsorption equilibrium constants or reaction rate parameters are essential in the design of adsorption systems or reactors in which sulfur dioxide is removed. The experiments were conducted in a temperature range of 523-718 K. The relatively strong adsorption properties of sulfur dioxide on zeolites necessitated the use of high carrier gas flow rates and subsequently non-isobaric operation. Non-isobaric pulse Chromatography theory was found to describe accurately the adsorption trends. Adsorption equilibrium constants of SO2 were found to decrease considerably with increasing temperature. It was also found out that adsorption of SO2 on the adsorbents investigated were found to decrease in the order of AW300 > 4A > 5A. The adsorption equilibrium parameter of SO2 on 5A was found as 11.78 at 673 K, whereas it has a value of 157.11 at 523 K. The adsorption equilibrium parameter of SO2 on 4A zeolite was determined to be 8.63 at 718 K and 213.78 at 523 K

Evaluation of a modified Jeffreys type model for viscoelastic fluids

In this study using some existing constitutive equations, a modified Jeffreys type model with retardation time is developed which is successful with the experimental data for simple shear flow and shear free flow. Nonlinear regression analysis based on Marquardt Algorithm is used for determination of material parameters for simple shear flow. The general form of the modified model is reduced by using the simple shear flow conditions and Oldroyd derivative for cartesian coordinates. In the determination of material parameters of the modified model is used experimental data of Leider and Lilleleht(1973) for viscometric functions. When viscometric functions of the modified model is compared with viscometric functions of the existing constitutive equations which use the material parameters of Leider and Lilleleht(1973), viscometric functions of the modified model is found to be more successful.In this study using some existing constitutive equations, a modified Jeffreys type model with retardation time is developed which is successful with the experimental data for simple shear flow and shear free flow. Nonlinear regression analysis based on Marquardt Algorithm is used for determination of material parameters for simple shear flow. The general form of the modified model is reduced by using the simple shear flow conditions and Oldroyd derivative for cartesian coordinates. In the determination of material parameters of the modified model is used experimental data of Leider and Lilleleht (1973) for viscometric functions. When viscometric functions of the modified model is compared with viscometric functions of the existing constitutive equations which use the material parameters of Leider and Lilleleht (1973), viscometric functions of the modified model is found to be more successful

Effect of plate spacing of impingement air jet on flow and heat transfer characteristics

In this paper the flow and heat transfer characteristics in the turbulent confinement impinging air jet have been numerically analyzed. Two-equation turbulence model, ?-?, have been used. Mass, momentum, energy, turbulent kinetic energy and turbulent kinetic energy dissipation rate equations were solved by the PHOENICS package program. Velocity, turbulent kinetic energy, turbulent kinetic energy dissipation rate and heat transfer characteristics in the impinging region have been predicted by finite volume scheme for the various plate spacings

Development of a new rate-type constitutive equation for viscoelastic fluid in the wiggle flow channel [Daralip-genişleyen kanalda viskoelastik bir akişkan için türev tipli yeni bir modelin geliştirilmesi]

In this study using some constitutive equations present in the literature, a rate-type constitutive equation is developed which is successful with the experimental results. The method being used is a nonlinear regression method that is known as Marquardt Method. Studies were done considering flow along the centerline of the flow channel. In this study the general form of the proposed constitutive equation was reduced on the centerline by using the flow kinematics and derivative operator for cartesian coordinates. Developing the difference of the normal stress components in the 1 - and 2- directions a nonlinear ordinary differential equation was obtained for the normal stress difference. When this differential equation that was reduced on the centerline was solved by this nonlinear regression method, model parameters, normal stress difference values along the centerline and sum of squares were determined simultaneously. When the proposed constitutive equation was compared with the existing equations, the proposed equation was found to be more successful in the flow along the centerline

Comparative evaluation of some existing rate-type constitutive equations for a viscoelastic fluid undergoing wiggle flow

A comparative evaluation of existing rate-type constitutive equations is provided for a viscoelastic fluid undergoing accelerated flow. To this end, accurate point velocity and stress birefringence data previously obtained by laser Doppler anemometry and stress birefringence are utilized. For each constitutive equation, the numerical values of constants which yield the best fit with experimental data are determined via non-linear regression analysis. The best agreement between experimental and calculated normal stress differences is obtained with the White-Metzner equation. The success of this equation is attributed to the deformation rate dependence of its viscosity and time constant. © 1997 Elsevier Science B.V. All rights reserved

Propagation of acceleration waves in the viscoelastic Johnson-Segalman fluids

The propagation conditions of acceleration waves are investigated for a viscoelastic fluid using the Johnson-Segalman viscoelastic model. Explicit expressions are obtained for the wave speeds adopting the theory of singular surfaces. The simple shearing motion, uniaxial, biaxial extension and uniform dilation are considered as the initial states of deformation. The variations of the speeds with the propagation direction, stretch ratio and material parameters are presented. © 2009 Elsevier Ltd. All rights reserved

The investigation of increasing of the efficiency in the power plant with gas-solid fuels by exergy analysis

In this study the energy and exergy analysis have been applied to the power plant in the Iron and Steel Works Co. This plant consist of two parts, which could be described as old and new sections. These components work together as an integrated power plant. In this work, the irreversibility rates and energy losses of each units have been determined separately by energy and exergy analysis. Also, units have been compared by irreversibility rates and some considerable suggestions have been made to improve efficiency. It is suggested to remove three pressure reduction units (PDD1, PDD2, PDD3), have a total irreversibility rate of 6054 kW, from the existing plant and replaced by a turbo-generator (TG4). Calculated results showed that the increments of overall thermal ( or first law) efficiency and overall exergy (or second law) efficiency of suggested plant were 2.27 and 2.21 %, respectively. ©2008 TIBTD Printed in Turkey

Effect of material parameters on rate-type constitutive equations in accelerated flow of viscoelastic fluids [Viskoelastik akiskanlarin ivmeli akisinda malzeme parametrelerinin turev tipli bunye denklemlerine etkisi]

The effect of material parameters on three rate-type constitutive equations (White-Metzner, Oldroyd 3-constant and Kopac-Arikol) used successfully according to the literature was investigated. The flow along the symetry axis of a converging-diverging flow channel was considered. In order to determine the effect of material parameters appearing in constitutive equations, the tensorial expressions of the models were reduced to the axis of symmetry, using derivative operators of models and flow kinematics. Arikol's values (1976, 1985) were used for the velocity and initial viscosity values appearing in reduced nonlinear ordinary differantial equations. The reduced constituve equations were solved numerically using the 4th order Runge-Kutta method. In these calculations, velocity and the 1st and 2nd derivatives of velocity were used as input in the equations. Solving the constitutive equations for 3 different values of the material parameters, the normal stress differences were determined along the axis of symmetry. The sum of squares between the calculated normal stress values and Arikol's(1976, 1985) experimental values were determined. As a result, the material parameters, sensitive and non-sensitive, were determined in each of the constitutive equations.The effect of material parameters on three rate-type constitutive equations (White-Metzner, Oldroyd 3-constant and Kopac-Arikol) used successfully according to the literature was investigated. The flow along the symmetry axis of a converging-diverging flow channel was considered. In order to determine the effect of material parameters appearing in constitutive equations, the tensorial expressions of the models were reduced to the axis of symmetry, using derivative operators of models and flow kinematics. Arikol's values (1976, 1985) were used for the velocity and initial viscosity values appearing in reduced nonlinear ordinary differential equations. The reduced constitutive equations were solved numerically using the 4th order Runge-Kutta method. In these calculations, velocity and the 1st and 2nd derivatives of velocity were used as input in the equations. Solving the constitutive equations for 3 different values of the material parameters, the normal stress differences were determined along the axis of symmetry. The sum of squares between the calculated normal stress values and Arikol's (1976, 1985) experimental values were determined. As a result, the material parameters, sensitive and non-sensitive, were determined in each of the constitutive equations

The feasibility energy analysis of catalagzi thermal electricity power plant for district heating application [ÇatalaGzi termIk elektrIk santralI Ile bÖlgesel isitma yapilabIlIrlIGIn enerjI analIzI]

In a conventional coal-fired power plant, which is only designed for electricity generation, while nearly 1/3 of fuel energy can be converted to useful energy, the other part of the energy is wasted as stack gases and cooling water of condensers. This waste energy could be recovered by modifying the plant as cogeneration system. It is possible to employ district heating by cogeneration system which generates both electricity and useful heat at the same time. In this study, Catalagzi Thermal Electricity Power Plant has been converted a cogeneration system in order to reduce waste energy amount that is transferred to the cooling water of condensers. To simply the steam extraction point, four different cycle model have been developed and the most appropriate steam extraction point has been identified. Steam extraction ratio has been increased from 0 to 0.5 in the amount of 0.05 and energetic analysis has been made for each case. The resuts have been showed that the most appropriate steam extraction point is the point that has made energy efficiency ratio maximum in power plant. © 2017 TIBTD Printed in Turkey