Products reactor formation simulation

Abstract In this paper, we discuss the results of a preliminary systematic process simulation study the effect of operating parameters on the product distribution and conversion efficiency of hydrocarbon fuels in a reforming reactor. The ASPEN One HYSYS-2004 simulation software has been utilized for the simulations and calculations of the fuel-processing reactions. It is desired to produce hydrogen rich reformed gas with as low as possible carbon monoxide (CO) formation, which requires different combinations of reformer, steam to carbon and oxygen to carbon ratios. Fuel properties only slightly affect the general trends. 

The possibility of the formation of gaseous reaction products in ion-bombarded solids exists either in the case of two different implanted elements reacting with each other or the implanted ions reacting with constituents of the target. There are two fields where such reactions play a major role. The first one is the fusion research where one expects hydrogen to react with the wall constituents of a fusion reactor, the second one is cosmochemistry where one knows that solar wind reacts at the surface of the moon or planets. In both cases the ion implantation technique is able to simulate the real processes. 

Other steps used in the model assume that the heterogeneous conversion of methane is limited to the gas-phase availability of oxygen, O2 adsorption is fast relative to the rate of methane conversion, and heat and mass transports are fast relative to the reaction rates. Calculations for the above model were conducted for a batch reactor using some kinetic parameters available for the oxidative coupling of methane over sodium-promoted CaO. The results of the computer simulation performed for methane dimerization at 800 °C can be found in Figure 7. It is seen that the major products of the reaction are ethane, ethylene, and CO. The formation of methanol and formaldehyde decreases as the contact time increases. 

By selecting process parameters, such as nature of the precursor, temperature, time, reactant state, and/or reactor geometry, product quality can be influenced. However, measurements in gas-phase reactors are a problem as times are extremely short, temperatures very high, and atmospheres often aggressive. Therefore, numerous models for process simulation, all based on particle population balances [B.91,11.1], have been developed as useful tools to better understand particle formation and support product and process optimization. 

Chromatographic batch reactors are employed to prepare instable reagents on the laboratory scale (Coca et al., 1993) and for the production of fine chemicals. These applications include the racemic resolution of amino acid esters (Kalbe, Hbcker, and Berndt, 1989), acid-catalyzed sucrose inversion (Lauer, 1980) and production of dextran (Zafar and Barker, 1988). Sardin, Schweich, and Viller-maux (1993) employed batch chromatographic reactors for different esterification reactions such as the esterification of acetic acid with ethanol and the transesterification of methylacetate. Falk and Seidel-Morgenstern (2002) have investigated the hydrolysis of methyl formate. Strohlein et al. (2006) measured the esterification of acrylic acid with methanol and validated the transport dispersive model for process simulation. 

No statements were made about the selectivity of product formation. In a more recent study kinetic measurements were made in a supension process carried out in an autoclave operating in the batch mode, and the results were used for the simulation of a trickle-bed reactor [15]. 

Stream Information. Directed arcs that represent the streams, with flow direction from left to right wherever possible, are numbered for reference. By convention, when streamlines cross, the horizontal line is shown as a continuous arc, with the vertical line broken. Each stream is labeled on the PFD by a numbered diamond. Furthermore, the feed and product streams are identified by name. Thus, streams 1 and 2 in Rgure 3.19 are labeled as the ethylene and chlorine feed streams, while streams 11 and 14 are labeled as the hydrogen chloride and vinyl-chloride product streams. Mass flow rates, pressures, and tempera-mres may appear on the PFD directly, but more often are placed in the stream table instead, for clarity. The latter has a column for each stream and can appear at the bottom of the PFD or as a separate table. Here, because of formatting limitations in this text, the stream table for the vinyl-chloride process is presented separately in Table 3.6. At least the following entries are presented for each stream label, temperature, pressure, vapor fraction, total and component molar flow rates, and total mass flow rate. In addition, stream properties such as the enthalpy, density, heat capacity, viscosity, and entropy, may be displayed. Stream tables are often completed using a process simulator. In Table 3.6, the conversion in the direct chlorination reactor is assumed to be 100%, while that in the pyrolysis reactor is only 60%. Furthermore, both towers are assumed to carry out perfect separations, with the overhead and bottoms temperatures computed based on dew- and bubble-point temperatures, respectively. 

The data obtained in the measurements showed that about 1% of the iodine inventory of the central fuel module reached the blowdown suppression tank, while only 0.23% of the cesium inventory appeared there. These data and those taken from the simulated broken line indicated that cesium deposited in this line more readily than iodine the reverse situation occurred in the upper plenum of the reactor pressure vessel. Here, almost no cesium was detected on the deposition coupons while iodine was present in amounts similar to those in the line of the low-pressure injection system. Besides iodine, silver was found on the upper plenum coupons in equivalent amoimts in addition, the iodine deposited on these coupons could not be leached by water, indicating that it was present there as an insoluble compound. From these data it was concluded that fission product iodine was transported out of the reactor core as Agl, rather than as Csl. Formation of Agl as the main iodine compound deposited in the upper plenum of the reactor pressure vessel is a behavior markedly different from that observed in other in-pile experiments and in the TMI-2 post-accident investigations. The reason for this behavior was assumed to be the low concentrations of both cesium and iodine present in the low-bumup fuel, which resulted in a very high stoichiometric excess... 

The Tennessee Eastman test-bed problem (Downs Vogel, 1993) involves the control of five unit operations. The simulated plant has 41 process variables and 12 manipulated variables as illustrated in Figure 2, which are nnodeled with 50 state variables. Out of 41 process variables there are 22 controllable outputs including level, pressure, temperature, flow and 19 composition indicators. The chemical reactions are irreversible and occur in the vapor space of the reactor. The formation of an inert byproduct, F, is undesirable. The products G and H accumulate in the reactor. In this paper the desired set point is 50% G and 50% H on a mass basis. By-product F may be present in the product with 97.5% of the product being composed of G and H. 

The coupled furnace-reactor simulation requires an accurate description of the heat transfer from the furnace to the reactor. The global radiative heat transfer from the furnace to the reactor was calculated by the zone method (Fig. 12.5.A-2, Left) proposed by Hottel and Sarofim [1967], To take into account the local influence of radiative heat transfer, CFD simulations of the furnace were carried out using a radiative heat transfer model for short distances [De Marco and Lockwood, 1975], Knowledge of the local flue gas composition is required to calculate the heat release by combustion in each flue gas volume element and the absorption coefficients for radiation. Coupled CFD simulations of the reactor tubes and furnace predict the process gas conversion and the product yields, as well as coke formation rates. 

Many researchers have identified the difference in the presence of hot spots (which locally enhance or promote some selected reactions or transformations). The narrow temperature distribution obtained by simulation can justify the formation of nanoparticles (having a narrower particle size distribution) with respect to conventionally heated synthetic routes in case of nucleation and growth of nanoparticles (microwave hydrothermal synthesis). The large-scale production of nanoparticles requires the development of microwave reactors, which can reflect the laboratory temperature profile homogeneity. It will provide a new dedicated eontinuous-flow reactor, made of two twin prismatic applicators for a microwave-assisted process in aqueous solution. The reactor can produce upto 1000 L/day of nanoparticles eolloi-dal suspension at ambient pressirre and relatively low temperature and henee, it ean be considered a green chemistry approach. 

In the absence of any mass-transfer resistance induced by the porous membrane, the continuous sweep of products in the gaseous phase effected a shift in thermodynamic equilibrium towards formation of alcohol. This was also demonstrated by the authors by introducing a convective mass transfer to the batch reaction model. In fact, a dynamic model of the reactor was also developed, and the results of simulations compared favorably with experiment and the performance of a commercially operated conventional reactor. 

---