TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Components: The process fluid comprises a synthesis gas. The catalyst is selected from a water-gas shift catalyst, a methanation catalyst, a methanol synthesis catalyst, and an ammonia synthesis catalyst. The process fluid is a synthesis gas mixture comprising hydrogen, carbon oxides and steam and containing one or more sulfur compounds, having a ratio, R, defined as R=((H2) - (CO2))/((CO)+(CO2)) less than or equal to 0.6 and a steam to carbon monoxide ratio less than or equal to 1.8, and the catalyst is a sulfur-tolerant water-gas shift catalyst. Preferred Condition: The synthesis gas and steam mixture is passed at temperatures in the range 190 to 420 degrees C and pressure up to about 85 bar abs, over the bed of water-gas shift catalyst. Preferred Process: The process further involves: (i) cooling the shifted synthesis gas stream obtained from the one or more further stages of water-gas shift, or a mixture of the shifted gas stream and a bypass stream, to below the dew point to condense water; (ii) separating the resulting condensate to form a dry shifted gas stream; (iii) feeding the dry shifted gas stream to a gas-washing unit operating by counter-current solvent flow, to produce a product synthesis gas enriched in hydrogen; and (iv) collecting the product synthesis gas from the washing unit.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: The header assembly is connected to the first end; or the header assembly is connected to the second end. The second end of the reactor is detachably mounted on the shell. The number of containment units is in the range 2-10, preferably 5-10. The reactor comprises a central containment unit aligned with the axis of the reactor, surrounded by 4-9 containment units spaced evenly around the central containment unit. Each containment unit comprises an outer perforate member an inner perforate member, arranged concentrically, and a central void within the inner perforate member to which or from which the process fluid may pass via the open end. The two perforate members are cylindrical such that each containment unit comprise an inner perforate cylinder and an outer perforate cylinder arranged concentrically to provide a regular annular space into which the particulate catalyst or sorbent may be placed. Each containment unit comprises a particulate catalyst or sorbent. The containment units are detachably mounted on the header assembly. The containment unit comprises a particulate sorbent for removing a component from the process fluid; or the containment unit comprises a particulate catalyst for converting a component of the process fluid. The reactor is used in combination with one or more adiabatic or gas-cooled reactors, each containing a suitable water-gas shift catalyst to produce a shifted synthesis gas stream.