NOVELTY - A compact fuel processing reactor includes discrete particles of a catalyst bed that are in intimate contact with a portion of coiled tubing of a heat exchanger. The coiled tubing has less than 25 m2 of heat exchanging surface area/m3 of catalyst bed.    USE - Used for converting hydrocarbon-based fuels into a hydrogen-enriched reformate used in fuel cells or other devices requiring hydrogen-rich feed streams.    ADVANTAGE - The compact fuel processing reactor is capable of reliably and stably carrying out various reforming and/or clean-up reactions using low pressure reactants. It can be used for a variety of fuel processing reactions without imposing a significant pressure drop on the reactants or process gas across the reactor.    DETAILED DESCRIPTION - A compact fuel processing reactor (10) comprises a housing (90) having an inlet (40) for receiving a process gas (20) and an outlet (50) for a directing a product gas (30) out of the housing. A catalyst bed (60) is located within the housing for contacting the process gas. It comprises discrete particles (70). A heat exchanger (80) is partially located within the catalyst bed for cooling the catalyst bed. It comprises a coiled tubing (86) and a stream of cooling medium flowing through the coiled tubing. The discrete particles are in intimate contact with a portion of the coiled tubing. The coiled tubing has less than 25 m2 of heat exchanging surface area/m3 of catalyst bed.    INDEPENDENT CLAIMS are also included for the following:    (A) cooling a catalyst bed within a compact reactor, comprising contacting a catalyst bed within a reactor with a process gas to catalyze a reaction to produce a product gas, passing a cooling medium through the catalyst bed within a coiled tubing heat exchanger, and exchanging heat between the catalyst bed and the coiled tubing; and    (B) manufacturing a compact shift reactor comprising providing a housing having a process gas inlet and a product gas outlet, locating a heat exchanger within the housing, and obtaining a mixture of catalyst and discrete particles and locating the mixture within the housing to form a catalyst bed.    The coiled tubing provides less than 25 m2 of heat exchanging surface area/m3 of catalyst bed. The process gas is at a first pressure and the product gas is at a second pressure and the difference between the two pressures is less than 3 psi/ft of reactor.    DESCRIPTION OF DRAWING(S) - The figure is a schematic view of a reactor, comprising a single catalyst bed.    Compact fuel processing reactor (10)    Process gas (20)    Product gas (30)    Inlet (40)    Outlet (50)    Catalyst bed (60)    Discrete particles (70)    Heat exchanger (80)    Coiled tubing (86)    Housing (90)