Temperature shift stage

Fig. 1.23. Flowsheet for a heat-integrated system of an autothermal gasoline reformer (ATR) and a high-temperature shift stage (HTS) interconnected with a heat exchanger [37].

An example of an experiment with a 2 factorial design is the analysis of the CO concentration after a water gas shift (WGS) reactor in a fuel cell system operating with reformate. In the example, the factors were selected as the inlet temperature of the shift reactor and the flow rate of quench water fed between the high- and low-temperature shift stages. The response of these values to the CO concentration as the target parameter was analyzed. In order to simplify the discussion, the values at the lower and upper levels were standardized as —1 and +1, respectively. The response functions were derived using the standardized values for each factor. 

Tungsten metal can be obtained by exposing tungsten oxides to dry hydrogen in a flow system maintained above about 500 °C. An increase in the temperature shifts the reaction towards metal formation. For the first two stages of reduction, corresponding to the forma-... 

Conventionally the reaction is performed in two stages, the so-called high- and low-temperature water-gas shift. In large-scale industrial processes, Fe203/Cr203 catalysts are applied for high-temperature shift (which is then performed between... 

Fluor Process. The Fluor process [280], [934], [940], [1094] uses the proprietary propylene carbonate based C02 removal system with adsorption refrigeration using low level heat downstream of the low-temperature shift. Methanation and C02 removal are placed between the compression stages and thus operate at higher pressure. With a value of 32 GJ/t NH3 [934] this is not really a low-energy concept. 

WGS reactors are usually divided into two or more stages, including high-temperature shift (HTS) reactor and low-temperature shift (LTS) reactor. This multistage design is necessary due to the strong exothermic nature of the WGS reaction ... 

Shift reaction. In the second step, known as a water-gas shift (WGS) reaction, the carbon monoxide produced in the first reaction is reacted with steam over a catalyst to form hydrogen and carbon dioxide. This process occurs in two stages a high temperature shift (HTS) at 350°C and a low temperature shift (LTS) at 190°C-210°C. 

The second stage contains a commercial low temperature shift (LTS). The shift reactors reduces the CO concentration in the reformate gas to approximately 2,000 ppm. Final reduction of CO is achieved in a preferential selective oxidation reactor. 

The catalyst scheme is summarized in Table 3. The required amount of Catalytica Energy Systems ATR catalyst was produced and installed in the reactor. The required amount of NexTech shift catalyst was produced and installed in the first stage shift reactor. The NexTech shift catalyst is a medium-temperature shift catalyst that remains active in the oxidized or reduced state and is less sensitive to condensed moisture [2]. All catalysts are currently in pellet form however, noble metal wash coating on monolith substrates is existing technology. Therefore, once the catalyst and system performance are verified, it will be straightforward to convert these catalysts to monoliths. The reactors... 

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