초록 ▼

A steam reforming furnace has a plurality of substantially vertical reformer tubes. Each reformer tube has a feed inlet at its lower end, an outlet at its upper end, and a catalyst containment zone disposed intermediate its upper and lower ends and contains a charge of a particulate steam reforming

A steam reforming furnace has a plurality of substantially vertical reformer tubes. Each reformer tube has a feed inlet at its lower end, an outlet at its upper end, and a catalyst containment zone disposed intermediate its upper and lower ends and contains a charge of a particulate steam reforming catalyst which is insufficient to fill completely the catalyst containment zone. An upper retainer means is mounted at the upper end of the catalyst containment zone and is permeable to gas or vapor but retains particles of the catalyst in the catalyst containment zone. A follower means is movably mounted in the catalyst containment zone beneath the charge catalyst for movement upwardly from a lower end of the containment zone upon upward flow of gas through the catalyst containment zone at a rate beyond a threshold rate.

대표청구항 ▼

The invention claimed is: 1. A steam reforming process in which a hydrocarbon feedstock is subjected to steam reforming by reaction under steam reforming conditions with steam in the presence of a steam reforming catalyst to produce a reformed gas mixture comprising carbon oxides and hydrogen, whic

The invention claimed is: 1. A steam reforming process in which a hydrocarbon feedstock is subjected to steam reforming by reaction under steam reforming conditions with steam in the presence of a steam reforming catalyst to produce a reformed gas mixture comprising carbon oxides and hydrogen, which process comprises the steps of: (a) providing a steam reforming furnace containing a plurality of substantially vertical reformer tubes, each reformer tube having a feed inlet at its lower end in communication with a reaction mixture feed manifold, an outlet at its upper end in communication with a reformed gas outlet header, and a catalyst containment zone disposed intermediate its upper and lower ends and containing a charge of a particulate steam reforming catalyst which is insufficient to fill completely the catalyst containment zone; (b) providing upper retainer means mounted at the upper end of the catalyst containment zone, the upper retainer means being permeable to gas but adapted to retain particles of the particulate steam reforming catalyst in the catalyst containment zone, and follower means movably mounted in the catalyst containment zone beneath the charge of particulate steam reforming catalyst for movement upwardly from a lower end of the containment zone upon upward flow of gas through the catalyst containment zone at a rate beyond a threshold rate; (c) supplying to the reaction mixture feed manifold a reactant mixture comprising the hydrocarbon feedstock and steam at a rate sufficient to cause the reactant mixture to flow upwardly through each reformer tube at a flow rate which is sufficient to cause the particulate steam reforming catalyst in each reformer tube to rise up towards the upper end thereof and form a cushion of particulate steam reforming catalyst against the underside of the upper retainer means in the respective reformer tube and which is in excess of the threshold rate so as to cause the follower means in the respective reformer tube to move upwardly until it abuts against the underside of the cushion of particulate steam reforming catalyst in the respective reformer tube; (d) heating each of the plurality of reformer tubes externally by means of the steam reformer furnace so as to maintain steam reforming conditions in each of the plurality of reformer tubes and convert the hydrocarbon feedstock by reaction with steam to form a reformed gas mixture comprising carbon oxides and hydrogen; and (e) recovering resulting reformed gas mixture from the reformed gas outlet header. 2. A process according to claim 1, wherein at least part of each of the reformer tubes has an internal diameter of about 6 inches (about 15.2 cm) or less. 3. A process according to claim 1, wherein at least part of each of the reformer tubes has an internal diameter of about 2 inches (about 5.08 cm) or less. 4. A process according to claim 1, wherein at least a part of each of the reformer tubes has an internal diameter of from about 1 inch (about 2.54 cm) to about 2 inches (about 5.08 cm). 5. A process according to claim 1, wherein the follower means in each of the reformer tubes is arranged to block passage of gas up the respective catalyst containment zone but permit upward gas flow through a clearance gap between the internal surface of the containment zone and the follower means, the clearance gap providing a clearance less than the smallest dimension of a non-fragmented particle of the particulate steam reforming catalyst. 6. A process according to claim 5, wherein the follower means comprises a closed lower end portion for defining the clearance gap and an upper portion provided with gas passing means. 7. A process according to claim 6, wherein the gas passing means comprises a plurality of substantially concentric rings spaced one from another, the clearance between adjacent rings being less than the smallest dimension of a non-fragmented particle of the particulate steam reforming catalyst. 8. A process according to claim 1, wherein the particles of the particulate steam reforming catalyst have at least one dimension less than about 10 mm. 9. A process according to claim 1, wherein the particles of the steam reforming catalyst are substantially spherical in shape. 10. A process according to claim 1, wherein prior to start up of the steam reformer furnace the particulate steam reforming catalyst is loaded into each of the reformer tubes via the top of its respective catalyst containment zone against an upflow stream of gas at a rate less than that required to lift fully the particles of the particulate steam reforming catalyst but such that the particles of the steam reforming catalyst do not fall freely under gravity. 11. A process according to claim 10, wherein after initial loading of a charge of the particulate steam reforming catalyst into a reformer tube, the pressure drop across the charge of particulate steam reforming catalyst in that reformer tube is measured in a measurement step. 12. A process according to claim 11, wherein particulate steam reforming catalyst is added to or removed from that reformer tube if the pressure drop measured does not conform to a predetermined value. 13. A process according to claim 11, wherein after initial loading of the charge of particulate steam reforming catalyst but prior to the measurement step a gas is caused to flow upwardly through the reformer tube so as to cause the particulate steam reforming catalyst to form a cushion of particulate steam reforming catalyst against the underside of the upper retainer means and so as to cause the follower means to move upwardly until it abuts against the underside of the cushion of particulate steam reforming catalyst, and thereafter the upward flow of gas is reduced or discontinued so as to permit formation of a settled bed of particulate steam reforming catalyst. 14. A process according to claim 10, wherein after initial loading of a charge of particulate steam reforming catalyst into a reformer tube the settled volume of the particulate steam reforming catalyst in the reformer tube is measured in a measurement step. 15. A process according to claim 14, wherein particulate steam reforming catalyst is added to or removed from the reformer tube if the settled volume of particulate steam reforming catalyst in the reformer tube does not conform to a predetermined value. 16. A process according to claim 1, wherein the steam reforming conditions include use of a temperature in the range of from about 750째 C. to about 900째 C. and a pressure of from about 100 psia (about 698.48 kPa) to about 600 psia (about 4136.86 kPa). 17. A process according to claim 1, wherein in step (d) the tubes are heated externally by means of flames directed downwardly from burners. 18. A process according to claim 17, wherein fuel supplied to the burners and combustion air therefor are preheated by heat exchange with the hot reformed gas. 19. A process according to claim 17, wherein the reactant mixture supplied from the reaction mixture feed manifold to the reformer tubes is heated by heat exchange with hot combustion gases from the downwardly directed flames. 20. A steam reforming furnace for steam reforming of a hydrocarbon feedstock by reaction under steam reforming conditions with steam in the presence of a steam reforming catalyst to produce a reformed gas mixture comprising carbon oxides and hydrogen, which comprises: (a) a furnace chamber; (b) a plurality of substantially vertical reformer tubes in the furnace chamber, each reformer tube having a feed inlet at its lower end in communication with a reaction mixture feed manifold, an outlet at its upper end in communication with a reformed gas outlet header, and a catalyst containment zone disposed intermediate its upper and lower ends and containing a charge of a particulate steam reforming catalyst which is insufficient to fill completely the catalyst containment zone; (c) burner means in the furnace chamber for externally heating the plurality of reformer tubes so as to maintain steam reforming conditions in each of the plurality of reformer tubes and convert the hydrocarbon feedstock by reaction with steam to a reformed gas mixture comprising carbon oxides and hydrogen; (d) upper retainer means mounted at the upper end of the catalyst containment zone of each of the plurality of reformer tubes, the upper retainer means being permeable to gas but adapted to retain particles of the particulate steam reforming catalyst in the catalyst containment zone; (e) follower means movably mounted in the catalyst containment zone beneath the charge of particulate steam reforming catalyst for movement upwardly from a lower end of the containment zone upon upward flow of gas through the catalyst containment zone at a rate beyond a threshold rate; (f) means for supplying to the reaction mixture feed manifold a reactant mixture comprising the hydrocarbon feedstock and steam at a rate sufficient to cause the reactant mixture to flow upwardly through each reformer tube at a flow rate which is sufficient to cause the particulate steam reforming catalyst in each reformer tube to rise up towards the upper end thereof and form a cushion of particulate steam reforming catalyst particles against the underside of the upper retainer means in the respective reformer tube and which is in excess of the threshold rate so as to cause the follower means in the respective reformer tube to move upwardly until it abuts against the underside of the cushion of particulate steam reforming catalyst in the respective reformer tube; and (g) means for recovering resulting reformed gas mixture from the reformed gas outlet header. 21. A steam reformer furnace according to claim 20, wherein at least a part of each of the reformer tubes has an internal diameter of about 6 inches (about 15.2 cm) or less. 22. A steam reformer furnace according to claim 20, wherein at least a part of each of the reformer tubes has an internal diameter of about 2 inches (about 5.08 cm) or less. 23. A steam reformer furnace according to claim 20, wherein at least a part of each of the reformer tubes has an internal diameter of from about 1 inch (about 2.54 cm) to about 2 inches (about 5.08 cm). 24. A steam reformer furnace according to claim 20, wherein the follower means in each of the reformer tubes is arranged to block passage of gas up the respective catalyst containment zone but permit upward gas flow through a clearance gap between the internal surface of the containment zone and the follower means, the clearance gap providing a clearance less than the smallest dimension of an undamaged particle of the particulate steam reforming catalyst. 25. A steam reformer furnace according to claim 24, wherein the follower means comprises a closed lower end portion for defining the clearance gap and an upper portion provided with gas passing means. 26. A steam reformer furnace according to claim 25, wherein the gas passing means comprises a plurality of substantially concentric rings spaced one from another, the clearance between adjacent rings being less than the smallest dimension of an undamaged particle of the particulate steam reforming catalyst. 27. A steam reformer furnace according to claim 20, wherein the particles of the particulate steam reforming catalyst have at least one dimension less than about 10 mm. 28. A steam reformer furnace according to claim 20, wherein the particles of the steam reforming catalyst are substantially spherical in shape. 29. A steam reformer furnace according to claim 20, further including means for supporting the follower means at the lower end of the catalyst containment zone when the upward flow of gas is less than the threshold rate. 30. A steam reformer furnace according to claim 20, wherein the burner means are disposed at a predetermined height within the furnace in relation to the upper retainer means. 31. A steam reformer furnace according to claim 20, wherein the burner means are adapted and arranged to provide a plurality of downwardly directed flames within the furnace chamber. 32. A steam reformer furnace according to claim 31, wherein a heat exchanger section is provided above reformer tubes for heating fuel for the burner means and combustion air therefor by heat exchange with the hot reformed gas. 33. A steam reformer furnace according to claim 31, wherein the feed inlets are heated by hot combustion gases from the downwardly directed flames to effect heating of the reactant mixture from the reactant mixture manifold. 34. A steam reformer furnace according to claim 31, wherein upon disconnection of the feed inlets for maintenance purposes the tubes can be lifted as a bundle for removal from the furnace chamber.