Heat exchange steam-reforming process and reactor

Claim 2

A process for the steam reforming of hydrocarbons in a reforming reactor by the passage of a feed stream comprising steam and one or more hydrocarbons as process gas under steam reforming conditions and under external supply of heat through a given volume of steam reforming catalyst to form a product stream rich in hydrogen, comprising the following successive steps: (a) passing the process gas through a first portion of the steam reforming catalyst constituting 25-75% thereof, heat needed for the endothermic reactions occurring in the process gas and for heating the process gas being supplied partly from a moderately hot flue gas as defined under (b) and partly from the product stream, and then (b) passing the process gas partly reformed in step (a) through the remaining portion of the steam reforming catalyst, the heat needed for the further endothermic reactions and heating of the process gas being supplied by a hot flue gas generated by combustion of a fluid fuel, the hot flue gas being thereby cooled to form the moderately hot flue gas employed in step (a).

Claim 3

A process as claimed in claim 1, wherein the moderately hot flue gas and the product stream, supplying the heat in step (a), are passing simultaneously and separately counter-currently in indirect heat exchange contact with the process gas passing step (a), whereas the hot flue gas supplying the heat to the process gas in step (b) is passing co-currently in indirect heat exchange contact with the process gas passing step (b) to form the product stream.

Claim 4

A process as claimed in claim 1, wherein the steam reforming conditions comprise a steam to carbon ratio in the feed stream of 1.5 to 7.0 as hereinbefore defined, a feed stream temperature of 350 to 550°C, a product stream temperature of 750 to 950°C when leaving the said remaining catalyst portion, and a process gas pressure of 2 to 45 bar.

Claim 5

A process as claimed in any of the preceding claims, wherein the hydrocarbon is natural gas and the steam to carbon ratio is 2.0 to 4.5.

Claim 6

A process as claimed in any of the preceding claims, wherein the steam reforming conditions further comprise a space velocity as hereinbefore defined of 100 to 4,000.

Claim 7

A reactor for carrying out the steam reforming process defined in any of the preceding claims, which comprises a pressure shell (20) with a removable lid (21), a burner (23), a combustion chamber (27), means for passing a feed stream (10) as a process gas (11) from at least one inlet (44) via a reforming catalyst to at least one outlet (50), and means for transferring heat by indirect heat exchange to the process gas (11), with the following combination of elements: (i) a first (41) and second (43) catalyst compartment adapted to hold each a portion (40, 42) of a catalyst constituting 25-75% and 75-25% respectively of the total volume of the catalyst and to receive heat through the compartment walls by indirect heat exchange for heating the process gas (11) and for the endothermic reactions occurring in the process gas during its passage over the catalyst, (ii) one or more passageways (45, 46, 47, 48, 49, 50) for passing the process gas (11) from the inlet (44) via the first and the second catalyst compartment (41, 43) in that order to the outlet (50), (iii) at least one section (49, 50) of the passageways mentioned under (ii) being adapted to pass product stream (12) from the second catalyst compartment (43), in indirect heat exchange contact with the process gas (11) passing the first catalyst compartment (41), to the outlet (50), (iv-) passageways (51, 52, 53) for passing flue gas from the combustion chamber (27) in indirect heat exchange contact first as hot flue gas (13) with the process gas (11) in the second catalyst compartment (43) and then as moderately hot flue gas (14) with the process gas (11) in the first catalyst compartment (41), the flue gas finally being discharged as cooled flue gas (15) through at least one outlet (54).

Claim 8

A reactor as claimed in claim 6, wherein the passageways (49, 50) for passing the product stream (12) from the second catalyst compartment (43) in indirect heat exchange contact with the process gas (11) passing the first catalyst compartment (41) are adapted and positioned so as to direct the product stream (12) counter-currently to process gas (11) passing the first catalyst compartment (41).

Claim 9

A reactor as claimed in claims 6 or 7, wherein the passageways (51, 52, 53) for passing the flue gas in indirect heat exchange contact first with the process gas (11) in the second catalyst compartment (43) and then with the process gas (11) in the first catalyst compartment (41) are adapted and positioned so as to direct the hot flue gas (13) co-currently with the process gas (11) passing the second catalyst compartment (43) and the moderately hot flue gas (14) counter-currently with the process gas (11) passing the first catalyst compartment (41).