GB1229415A - - Google Patents

Abstract

1,229,415. CO 2 acceptors. CONSOLIDATION COAL CO. 15 July, 1968 [19 July, 1967 (2)], Nos. 33225/67 and 33226/67. Heading C1A. In a process in which CaO is used to absorb CO 2 and form CaC0 3 which is then calcined to form CaO for re-use as a C0 2 -acceptor, which by repeated recycling becomes less effective as a CO 2 -acceptor, restoration of deactivated CaO to an effective CO 2 acceptor is achieved by (a) converting said deactivated CaO to Ca(OH) 2 , e.g. with water, (b) heating a mixture of said Ca(OH) 2 , preferably in a 1: 1 molar ratio, with CaO and/or CaCO 3 in the presence of steam at a pressure sufficiently high to prevent dehydration of the Ca(OH) 2 until the mixture has melted, (c) allowing the melt to cool to a solid state, and (d) calcining the Ca(OH) 2 to CaO which is an active C0 2 acceptor. Additives such as acidic oxides, carbonates, phosphates, e.g. P 2 0 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Na 2 CO 3 may be added to the melt to inhibit CaO crystal growth. In an embodiment, CaO is used to absorb C0 2 formed as a by-product in the steam-carbon reaction for the production of CO, CH 4 and H 2 , said CaO being regenerated as an active C0 2 acceptor by feeding a mixture of CaO and CaC0 3 heated to 600-800‹ F. from a hopper into a stirred reactor into which steam and CO 2 at 350-1000 p.s.i.g. is fed, the temperature being maintained at 1200-1400‹ F., thereby forming a molten product containing about 50 mole per cent of both Ca(OH) 2 and CaCO 3 . The molten product is cooled in a prilling tower and the granules formed are crushed, calcined and returned to the steam-carbon process. '