Converter design

Ammonia concentration (vol %) Cooling Quench Quench Quench 12 

Notes 1. Total synthesis gas volume for 1000 tes/day production is 600,00 m /h with 33—42% being used as quench at 140°C. 

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Quench Converter. The quench converter (Fig. 7a) was the basis for the initial ICl low pressure methanol flow sheet. A portion of the mixed synthesis and recycle gas bypasses the loop interchanger, which provides the quench fractions for the iatermediate catalyst beds. The remaining feed gas is heated to the inlet temperature of the first bed. Because the beds are adiabatic, the feed gas temperature increases as the exothermic synthesis reactions proceed. The injection of quench gas between the beds serves to cool the reacting mixture and add more reactants prior to entering the next catalyst bed. Quench converters typically contain three to six catalyst beds with a gas distributor in between each bed for injecting the quench gas. A variety of gas mixing and distribution devices are employed which characterize the proprietary converter designs. 

In various fields of commercial catalyst practice, it has been customary for more than 30 years (I) to use a very simple first order, or psuedo first order, equation in preliminary converter design where very great changes in conditions are not made. This equation, for constituent X, may be written as... 

Vehicle data represents the complex interaction of many variables, including vehicle performance, reactor design and location, as well as catalyst properties. For a catalyst that has failed, one must ponder whether the converter design used in the vehicle is suitable for the catalyst, the quantity of the catalyst used is correct, the distance of the converter from the exhaust manifold is suitable, the catalyst has been inadvertantly overheated to above 2000°F or poisoned by lead and sulfur, or whether the catalyst can be modified to produce a far superior product. 

It is worth mentioning that the results discussed in Sections 3.1 and 3.2 provide a rationale behind the recent trends toward a close-coupled converter location as well as dual-brick converter design (i.e., a relatively small-voltmie catalyst brick with high Pd loadings followed by a larger Pt/Rh catalyst brick) in order to improve converter lightofF performance without excessive noble metal usage. 

Artifical Solar Energy Converters Designed to Mimic Photosynthesis... 

Automotive emission control, 10 30-67 for alternative fuels, 10 59-60 alternative systems, 10 58-59 catalytic converter chemical reactions and surface chemistry, 10 46—50 catalytic converter design, 10 39—46 diesel engine, 10 60-62 emission control system, 10 38-39 emission regulation and testing, 10 31-35... 

Fielder, 1989] Fielder, L. D. (1989). Fluman Auditory Capabilities and Their Consequences for Digital Audio Converter Design. In Pohlmann, K., editor, Audio in Digital Times, pages 45-62. Audio Engineering Society. 

After final cooling, the synthesis gas is compressed (7) and sent to the synthesis loop. The loop can operate at pressures between 70 to 100 bar. The converter design does impact the loop pressure, with radial-flow designs enabling low loop pressure even at the largest plant size. Low loop pressure reduces the total energy requirements for the process. 

Also obtainable from abb.com is PCS 500 - Power Converter Systems modular standard converter system, showing PEBBs (Power Electronics Building Blocks) a modular approach to converter design. 

For a long time efforts to improve the efficiency of industrial ammonia production concentrated on synthesis gas production, and major progress was achieved over the years. In ammonia synthesis itself considerable progress was made in converter design and recovery of the reaction enthalpie at high temperature, but there has been no substantial improvement in the catalyst since the 1920s. The standard commercial iron... 

It has been already mentioned briefly, that compared to the synthesis section itself, where of course some progress has been made in converter design and optimization of heat recovery, the more fundamental changes over the years have occurred in synthesis gas preparation and gas compression. It is therefore appropriate to discuss the various methods for the synthesis gas generation, carbon monoxide shift conversion, and gas purification in some detail. Figure 29 shows schematically the options for the process steps for ammonia production. 

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... 

Kellogg has developed for its ruthenium catalyst based KAAP ammonia process [404], [478] a special converter design. Four radial flow beds are accommodated in a single pressure shell with intermediate heat exchangers after the first, second and third bed. The first bed is loaded with conventional iron catalyst, the following ones with the new ruthenium catalyst. Figure 95 is a simplified sketch of the converter and the synthesis loop of the KAAP for a new plant. For revamps Kellogg has also proposed a two-bed version completely loaded with ruthenium catalyst to be placed downstream of a conventional converter [398]. 

Three different converter applications are discussed to illustrate not only the variable operating conditions, but also the effectiveness of the systems approach in optimizing converter design for the passenger car (for both close-coupled and underbody locations) and the heavy-duty gasoline truck. These examples should prove valuable in designing other converter systems for which automakers requirements and component suppliers limitations are even more challenging ... 

Calderbank, P. H. 1953. Contact-process converter design. Chem. Eng. Progr. 49, 585-590. 

Only those aspects of nitric acid and HCN manufacture related to converter design and operation will be considered here. While the design of acid absorption and heat recovery sections certainly depends on the type of converter employed, these aspects have been well dealt with elsewhere. There are two main groups of problems, namely, those affected by heat and mass transfer and those concerned with changes in the state of the catalyst. 

There exist numerous designs for the converter. The boundary conditions for the converter design are the space which is available in the vehicle platform to mount the converter and the overall volume of catalyst needed for the catalytic function. A single converter can be packed with one single or with more, typically two or sometimes three, single pieces of ceramic monolith. When multiple pieces are used, they are mounted with a well defined distance between them, to effect turbulent flow conditions at the inlet to each piece. 

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