Steam simplified scheme

A simplified scheme of the RCH/RP unit is presented in Figure 2 [1, 10, 11], The reactor (1) is essentially a continuous stirred tank reactor equipped with a gas inlet, a stirrer, a heat exchanger and a catalyst recycle line. Catalyst and reactants are introduced at the bottom of the reactor. Vent gas is taken from the head of the reactor and from the phase separator. Control of the liquid volume inside the reactor is simple the liquid mixture composed of catalyst solution and aldehydes leaves via an overflow and is transferred to a phase separator (2), where it is partially degassed. The separation of the aqueous catalyst solution (density of the catalyst solution 1100 g/L) and the aldehydes occurs rapidly and completely, favored by the difference in densities (density of aldehyde layer 600 g/L due to dissolved gases). The catalyst solution passes a heat exchanger and produces process steam that is consumed in downstream operations. Some water is extracted from the catalyst solution by its physical solubility in the aldehydes (about 1.3% w/w) which may be replaced before the catalyst solution re-enters the reactor. 

One of the most promising methods for making coal a more efficient and cleaner fuel involves the conversion of coal to a gaseous form, called syngas for "synthetic gas." This process is called coal gasification. In the presence of very hot steam and air, coal decomposes and reacts according to the following simplified scheme ... 

Figure 6.6.6 Simplified scheme of a steam cracker, showing the cooling and compression steps behind the cracking furnace the gas leaving the multi-stage compression enters the separation scheme illustrated in Figur 6.6.7. Adapted from Marti (1996).

In the Texaco process, if the desired product is hydrogen, the raw syngas leaving the reactor is cooled with a direct-water-quench system. In this way, the steam necessary for the downstream shift reaction is produced in situ. A simplified flow diagram depicting the process flow scheme with the direct-quench cooling system is shown in Figure 13 [17). 

The use of a two circuit scheme instead of a 3-circuit one (elimination of intermediate heat transport system) and the absence of on-site refuelling facilitate simplification of the primary circuit design. The absence of steam generators, steam condensers, water chemistry and purification units and others significantly simplifies the design of the turbine circuit. As a result, the relative weight of the BN GT main equipment is about 5 t/MW(e) while serial PWRs have 15-20 t/MW(e) and some APWR designs over 25 t/MW(e). 

Figure 6.6.7 Simplified view of the whole product separation and purification scheme of a steam cracker operating on naphtha. Adapted from HaertI etal., (1996).

Figure 15 shows simplified flow schemes of the two alternatives. The indirect route to methanol is based on steam reforming followed by methanol synthesis. The process consumes ca. 7 Gcal/t corresponding to a thermal efficiency of 68%. The synthesis gas route may also lead to gasoline by further conversion of methanol via the Mobil MTG-process (Yurchak, 1988) or by the Topsoe TIGAS process (Topp-Joergensen, 1988). 

However, reactions (12.47) to (12.49) above still represent a very simplified reaction scheme because the cracking process is usually highly complex. In any case, the anode material in SOFGs must be able to oxidize the cracking products, and especially the formed carbon at sufficient rates. The formed carbon (coke) can also be removed by steam or carbon dioxide ... 

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