Bent tube waste heat steam generator and method

A heat exchanger for use in a catalytic regenerator heat recovery system using spent catalyst from a catalytic reactor as a heat exchange medium, said heat exchanger comprising:

• a lower manifold defining an inlet thereinto;
• an upper manifold spaced from said lower manifold and defining an outlet therein;
• and
• a plurality of substantially C-shaped tubes, each of said tubes having a lower end connected to said first manifold and an upper end connected to said upper manifold, said tubes being adapted for contact by said spent catalyst along at least a portion of an outer surface of said tubes for heating a fluid discharged from said lower manifold to said tubes and for discharge of heated fluid from said tubes into said upper manifold.

A method of generating steam in a catalytic regenerator comprising the steps of:

• flowing water from a downcomer into as substantially horizontal first manifold;
• discharging water from said first manifold into lower ends of a plurality of vertically oriented C-shaped tubes in communication with said first manifold;
• applying heat from hot catalyst particles disposed around at least a portion of the outside of said tubes, said heat being sufficient to boil said water such that steam is produced in said tubes;
• discharging said steam from upper ends of said tubes into a substantially horizontal second manifold in communication with said upper ends and spaced above said first manifold;
• and
• discharging said steam from said second manifold into a riser.

A regenerator apparatus comprising:

• a shell portion containing a heat exchange medium;
• heat exchanger means containing another heat exchange medium and comprising:
• upper manifold means;
• lower manifold means;
• and
• a plurality of substantially C-shaped tubes interconnecting said upper and lower manifold means;
• and
• a shield disposed in said shell portion above at least one of said upper and lower manifold means.

A method of generating steam in a regenerator comprising the steps of:

• flowing water from a downcomer into a substantially horizontal first manifold;
• discharging water from said first manifold into lower ends of as plurality of vertically oriented C-shaped tubes in communication with said first manifold;
• applying heat to said tubes sufficient to boil said water such that steam is produced in said tubes;
• discharging said steam from upper ends of said tubes into a substantially horizontal second manifold in communication with said upper ends and spaced above said first manifold;
• shielding within the regenerator the upper surface of at least one of said upper and lower manifolds;
• and
• discharging said steam from said second manifold into a riser.