R. Krishna Prasad

Color removal from distillery spent wash through coagulation using Moringa oleifera seeds: Use of optimum response surface methodology

The effects of dosage, pH and concentration of salts were investigated for an optimized condition of color removal from the distillery spent wash. The optimization process was analyzed using custom response surface methodology (RSM). The design was employed to derive a statistical model for the effect of parameters studied on removal of color using Moringa oleifera coagulant (MOC). The dosage (20 and 60 ml), pH (7 and 8.5) and concentration of 0.25 M had been found to be the optimum conditions for maximum 56% and 67% color removal using sodium chloride (NaCl) and potassium chloride (KCl) salts respectively. The actual color removal at optimal conditions was found to be 53% and 64% respectively for NaCl and KCl salts which confirms close to RSM results. The effects of storage duration and temperature on MOC studied reveal that coagulation efficiency of MOC kept at room temperature was effective for 3 days and at 4 degrees C it performed coagulation up to 5 days.

Sorption of distillery spent wash onto fly ash: kinetics, mechanism, process design and factorial design.

Batch and continuous experiments were performed for the sorption of distillery spent wash onto fly ash particles. The Freundlich and pseudo-second order equation were found to fit the equilibrium data perfectly. The Weber-Morris intraparticle diffusion isotherm equation was used to predict the sorption mechanism and the predicted equation for 10% dilution of spent wash sorption is q(t)=1.1344t(0.5)+33.304. The optimization using 2(3) factorial design of experiments provides optimal removal of color of 93% for dilution (5%), dosage of adsorbent (10g) and temperature (293K). The actual color removal at optimal conditions was 92.24%, confirms close to the factorial design results. The complete error analysis using six non-linear error functions: Chi-square (chi(2)); sum of square errors (SSE); composite fractional error function (HYBRD); derivative of Marquardts percent standard deviation (MPSD); average relative error (ARE); sum of absolute errors (EABS) were calculated. Free energy of adsorption at 293K (DeltaG(0)=-1574.67J), enthalpy change (DeltaH(0)=-32.5487KJ) and entropy change (DeltaS(0)=105J/K) were calculated to predict the nature of adsorption. Adsorption studies in a packed column were evaluated using Bed depth service time model, Thomas model and Adams-Bohart model.

Carbon nanotubes dispersed polymer nanocomposites: mechanical, electrical, thermal properties and surface morphology

The various properties and surface morphology of the carbon nanotubes (CNTs) dispersed polydimethyl siloxane (PDMS) matrix were studied to determine their usefulness in various applications. The tensile strength, Young’s modulus and electrical breakdown strength of CNT/polymer composites were 0.35 MPa, 1.2 MPa and 8.1 kV, respectively. The thermal conductivity and dielectric constant for the material having 4.28 wt% CNT were 0.225 W m−1 K−1 and 2.329, respectively. The CNT/polymer composites are promising functional composites with improved mechanical and electrical properties. The scanning electron microscope analysis of surface morphology of PDMS/CNT composite showed that the rough surface texture on nanocomposite has large surface area with circular pores. The Fourier transform infrared spectroscopy showed the functional groups present in polymer nanocomposite.

Process Simulation and Modeling of Fluidized Catalytic Cracker Performance in Crude Refinery

The simulation of fluidized catalytic cracking (FCC) process was performed using Aspen HYSYS. The effect of crude flow rate on naphtha flow, coke yield, and catalyst to oil ratio in FCC were simulated. The interaction effects of riser height, inlet crude flow rate and operating temperature on naphtha mass flow, catalyst to oil ratio, and coke yield were studied by Box-Behnken design. The maximum yield of naphtha (100000 kg/h) was obtained for FCC operating temperature within 520–600°C and riser height greater than 30 m. The catalyst to oil ratio of above 12 was obtained for operating temperature beyond 590°C for the entire riser height variation of 10 to 60 m in FCC. The increase in riser height resulted in increase production of naphtha, but beyond 60 m of riser height secondary cracking occurs resulting in reduction in yield of naphtha.

Grinding kinetics, modeling, and subsieve morphology of ball mill grinding for cement industry ingredients

ABSTRACT The dependence and interactions of various factors affecting the ball mill grinding like diameter of ball, particle size, and time of grinding on 80% passing size of product d80 was studied for cement industry raw materials of lime stone and sand using Box–Behnken design of response surface experiments. The bond grindability index and work index of ball mill were determined for different feed characteristics by varying the number of balls involved in grinding operation in the ball mill. The higher specific rate of breakage was obtained for new or smooth surfaced balls than old or rough surfaced balls. The reduction in size due to ball mill grinding was found to be better for wet grinding than dry grinding based on specific rate of breakages obtained. The subsieve morphology of particles in sieve pan for sand for both dry and wet grinding were analyzed using scanning electron microscopic observations to determine the breakage characteristics.

Process Modeling and Particle Flow Simulation of Sand Separation in Cyclone Separator

The Box–Behnken design of mathematical model for cyclone separator was developed for the interactions of particle size, feed load, and pressure drop in the cyclone separator to determine the collection efficiency of sand particles. The collection efficiency of 90% and above was obtained by operating the cyclone separator in pressure drop range of 197–490 Pa for diameter of sand particles in the range of 200–800 µm. The axial and tangential velocities were evaluated using Barth model for the cyclone separator studies. The studies were used to determine the contour regions of pressure fields and various velocity fields using computational fluid dynamics software Fluent for the purpose of flow analysis in the cyclone separator. The static pressure reduces from the wall to the center and negative pressure zone exists at central region due to presence of vortex zone.

Kinetics and characterization of transesterification of cottonseed oil to biodiesel using calcined clam shells as catalyst

ABSTRACT The synthesis of biodiesel from cottonseed oil using heterogeneous calcined clam shells by transesterification was studied. The effects of the amount of catalyst and the oil-to-methanol ratio on the yield of the biodiesel produced were determined. A maximum yield of 84% biodiesel was obtained. Various characterization tests such as Fourier transform infrared spectroscopy (FT-IR), Gas Chromatography - Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy were carried out to ascertain the functional groups and compounds available in the product biodiesel obtained. The properties of the biodiesel using the calcined clamshell catalyst, such as density, viscosity, saponification value, iodine value and ester value, were estimated and compared with the American Society for Testing Materials standard values to determine the quality of the biodiesel produced. The yield of the biodiesel produced was modelled using response surface methodology, and contour regions were obtained. The surface morphology of the catalyst was studied using a scanning electron microscope. From the kinetics results obtained, the forward rate constant of the adsorption of methanol onto the catalyst surface was found to be very low (1.467 × 10−4), confirming that the kinetics of biodiesel production is limited by adsorption of methanol onto the active sites of the catalyst.

Simulation of fly ash particulates separation in cyclone separator

The response surface Box-Behnken design is used to study the dependence and interactions of particle size, load of fly ash and pressure drop inside the cyclone separator for collection efficiency of fly ash. The maximum collection efficiency of fly ash obtained was 95% in the cyclone separator studied. The Barth model is used to evaluate the axial and tangential velocities of cyclone separator studied. The static pressure contour plots at different inlet velocities of 41 m/s and 104 m/s at top and bottom horizontal planes of cyclone separator were developed using computational fluid dynamics software Fluent. The contour regions of axial, radial and tangential velocity fields in the cyclone separator were analysed using Fluent finite volume code for flow analysis inside the cyclone separator for fly ash collection. It was observed that the radial velocity increases rapidly towards the vortex core and the tangential velocity is dependent on the geometrical design of cyclone separator, wall friction and particle loading of fly ash.