Ammonia synthesis reactors

If all of the N2 were to react, 300 lb mol of ammonia would be produced while if all of the hydrogen were to react, 348.6 lb mol ammonia would be produced. N2 is the limiting reactant. 

Five pounds of bismuth (MW = 209) is heated along with one pound of sulfur to form Bi2S3 (MW = 514). At the end of the reaction, the mass is extracted and the free sulfur recovered is 5 % of the reaction mass. Determine 

We will assume that no gaseous products are formed, so that the total mass of the reaction mixture is conserved at 6 lb (5 lb Bi + 1 lb S). The free sulfur at the end of the reaction = 

CHAPTER 1 - ADDITIONAL PROBLEMS (Answers will be found in Appendix A) 

ID An elevator which weights 10,000 lb is pulled up 10 ft between the first and second 

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Table 8.6. Typical composition of the feed gas when it enters the ammonia synthesis reactor.

Ammonia synthesis reactor. The shaded area contains the catalyst. [Adapted, with permission, from Murase et al., Optimal Thermal Design of an Auto-thermal Ammonia Synthesis Reactor, Ind Eng Chem Process Des Dev 9 504 (1970). Copyright, American Chemical Society.]... 

In order to illustrate this approach, we next consider the optimization of an ammonia synthesis reactor. Formulation of the reactor optimization problem includes the discretized modeling equations for a packed bed reactor, along with the set of knot placement constraints. The following case study illustrates how a differential-algebraic problem can be optimized efficiently using (27). In addition, suitable accuracy of the ODE model can be obtained at the optimum by directly enforcing error restrictions and adaptively adding elements. Finally, bounds on the continuous state profiles can be enforced directly in the optimization problem. 

Fig. 4. Schematic of ammonia synthesis reactor. Reprinted with permission from Comp. Chem. Eng., 14, No. 10, 1083-1100, S. Vasantharajan and L. T. Biegler, Simultaneous Optimization of Differential/Algebraic Systems with Error Criterion Adjustment, Copyright 1990, Pergamon Press PLC.

Murase, Akira, Roberts, Howard L., and Converse, Alvin O., Optimal thermal design of an autothermal ammonia synthesis reactor, l EC Proc. Des. Dev. 9(4), 503 (1970). 

Modem ammonia synthesis reactors operate at -200 atm at -350°C and produce nearly the equihhrirrm conversion ( 70%) in each pass. The NH3 is separated from unreacted H2 and N2, which are recycled back to the reactor, such that the overaU process of a tubular reactor plus separation and recycle produces essentially 100% NH3 conversion The NH3 synthesis reactor is fairly small, and the largest components (and the most expensive)... 

Figure 3-17 Plot of eqdlibrimn convereion Xg vasus terr5)er-ature for ammonia synthesis starting with stoichiomeh ic feed. While the equilibrium is favorable at anbient tar5)erature (where bactaia fix N2), the convasion r dly falls off at elevated temperature, and commercial ammonia synthesis reactors operate with a Fe catalyst at pressiues as high as 300 atm to att 2 high equilibrium conversion.

Figure 8. Designs of ammonia synthesis converters (a) Principle of the autothermal ammonia synthesis reactor (b) Radial flow converter with capacities of 1,800 tpd (c) Horizontal three-bed converter and detail of the catalyst cartridge. (Source Walas, M. S., Chemical Process Equipment, Selection and Design, Butterworth Series in Chemical Engineering, 1988.)...

Knowledge of the macrokinetics is important for solving the industrial problem of designing ammonia synthesis reactors, for determining the optimal operating conditions and for computer control of ammonia plants. Some of the considerations are ... 

Forced Composition Cycling Experiments in a Fixed-Bed Ammonia Synthesis Reactor... 

The effect of feed composition cycling on the time-average rate and temperature profile was explored in the region of integral conversion in a laboratory fixed bed ammonia synthesis reactor. Experiments were carried out at 400°C and 2.38 MPa over 40/50 US mesh catalyst particles. The effect of various cycling parameters, such as cycle-period, cycle-split, and the mean composition, on the improvement in time-average rate over the steady state were investigated. 

Singh, C P., SaraC D. N, Sanulafion of ammonia synthesis reactors". Indtao, md Ei Ttg Chem. ProAiet... 

Perhaps the first published analysis of an RFBR was by Raskin et al. (4), who developed a qua si continuum model for a radial ammonia synthesis reactor and later applied it to carbon monoxide conversion (5). 

Converter Design. Design of ammonia synthesis reactors is not just the calculation of the required catalyst volume other parameters have to be considered, too, and for... 

Comparison of calculated and measured ammonia concentrations at the effluent of a steady-steady ammonia synthesis reactor containing ruthenium particles supported on magnesia and promoted by cesium. [Adapted from O. Hinrichsen. F Rosowski, M. Muhler, and G. Ertl, The Microkinetics of Ammonia Synthesis Catalyzed by Cesium-Promoted Supported Ruthenium, Chem. Eng. Sci., 51 (1996) 1683, copyright 1996, with permission from Elsevier Science.]... 

The feed to an ammonia synthesis reactor contains 25 mole% nitrogen and the balance hydrogen. The flow rate of the stream is 3000 kg/h. Calculate the rate of flow of nitrogen into the reactor in kg/h. Suggestion First calculate the average molecular weight of the mixture.)... 

A.K. Jain. P.L. Silveston. and R.R. Hudgins, Forced composition cycling experiments in a fixed-bed ammonia synthesis reactor. Chem. Reaction. Eng. 9 97 (1982). 

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