HTS reactors

This reaction is first conducted on a chromium-promoted iron oxide catalyst in the high temperature shift (HTS) reactor at about 370°C at the inlet. This catalyst is usually in the form of 6 x 6-mm or 9.5 x 9.5-mm tablets, SV about 4000 h . Converted gases are cooled outside of the HTS by producing steam or heating boiler feed water and are sent to the low temperature shift (LTS) converter at about 200—215°C to complete the water gas shift reaction. The LTS catalyst is a copper—zinc oxide catalyst supported on alumina. CO content of the effluent gas is usually 0.1—0.25% on a dry gas basis and has a 14°C approach to equihbrium, ie, an equihbrium temperature 14°C higher than actual, and SV about 4000 h . Operating at as low a temperature as possible is advantageous because of the more favorable equihbrium constants. The product gas from this section contains about 77% H2, 18% CO2, 0.30% CO, and 4.7% CH. ... 

Figure 11.6. Lab VIEW interface to monitor and control the HT reactor system.

The main unit is the catalytic primaiy process reactor for gross production, based on the ATR of biodiesel. After the primary step, secondary units for both the CO clean-up process and the simultaneous increase of the concentration are employed the content from the reformated gas can be increased through the water-gas shift (WGS) reaction by converting the CO with steam to CO and H. The high thermal shift (HTS) reactor is operating at 575-625 K followed by a low thermal shift (LTS) reactor operating at 475-535 K (Ruettinger et al., 2003). A preferential oxidation (PROX) step is required to completely remove the CO by oxidation to COj on a noble metal catalyst. The PROX reaction is assumed to take place in an isothermal bed reactor at 425 K after the last shift step (Rosso et al., 2004). 

The material of construction in HTS reactors is usually low-alloy steel containing 1% Cr and 0.5% Mo. If CO2 and HjS are in the steam condensate that is fed to the shift conversion reactors, they should be made of 304 stainless steel to avoid corrosion problems88. 

The third HTS reactor will deliver product gas containing about 2.8% vol CO (on dry gas) to the low-temperature shift (LTS) section. Heat recovered from the LTS effluent is used to raise 90 psig steam and to preheat boiler feed water. 

The exit from the secondary reformer contains about 10-12% CO, is cooled to about 350°C and fed to a high-temperature water gas shift (HTS) reactor. 

In the traditional plant concept, the gas from the secondary reformer, cooled by recovering the waste heat for raising and superheating steam, enters the high-temperature shift (HTS) reactor loaded with an iron - chromium catalyst at 320 - 350 °C. After a temperature increase of around 50 - 70 °C (depending on initial CO concentration) and with a residual CO content of around 3 % the gas is then cooled to 200-210 °C for the low-temperature shift (LTS), which is carried out on a copper - zinc - alumina catalyst in a downstream reaction vessel and achieves a carbon monoxide concentration of 0.1-0.3 vol%. 

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 ... 

Water gas shift converters in industry are largely unchanged from their original design adiabatic fixed bed reactors with particulate catalysts. There are only two kinds of these reactors in use in industry today HTS and LTS. They differ in the operating temperatures and catalysts which they use. Two reactors are needed to convert the majority of CO, because of the equilibrium limitations of the process (see previous section). The inlet temperature of the HTS reactor is typically around 320°C. The outlet temperature rises to about 400-450° C because of the reaction exotherm. The gases are cooled to about 200°C before entering the LTS reactor, where the final 2-3% CO is partially converted to CO2 and H2. 

An example for the first case Upscaling from an appropriately scaled-down high-throughput testing device is the scale-up of a structured reactor or micro-structured reactor. For these reactors the important dimensions of the reactor zone can be the same as in the HT-reactor that is used for screening. For a monolith, which is the biggest representative for structured reactors, a single... 

Puertolano gasification plant. For the high CO concentrations in the syngas, it is necessary to use two HTS reactor stages, each of which operate with an inlet temperature of 350°C. 

The steam fed to the first HTS reactor from the gasifier has a steam to CO ratio of about 2. Extra steam from battery limits is required to bring the steam-to-CO ratio to 3.3 to meet the requirements of the catalyst. In Table 7.1 the material balance for the two HTS reactors is shown, based on hydrogen production of 25,000 Nm /h. 

Extended plant lifetime to 60 years, comparable to current Generation in/Ht + reactors, through... 

D.E. Buckthorpe, Results from E.E 5th framework HTR projects, in 2nd Int. Topical Meeting on HT Reactor Technology, Beijing, China, 2004. 

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