Apparatus for decomposing concentrated aqueous aluminum nitrate solutions

Claim 2

A FLUIDIZED BED ADAPTED FOR DECOMPOSITION OF AN AQUEOUS SOLUTION OF ALUMINUM NITRATE TO FORM AN ALUMINA PRODUCT AND NITRIC ACID, COMPRISING IN COMBINATION A. HOUSING MEANS DEFINING THEREIN A FLUIDIZED BED COMPRISING A CENTRAL REACTION SECTION, A FLUIDIZING GAS CHAMBER BELOW SAID REACTION SECTION AND SEPARATED FROM SAID REACTION SECTION BY A GRID PLATE, AND AN EFFLUENT GAS CHAMBER ABOVE SAID REACTION SECTION, B. FLUIDIZABLE BED PARTICLES IN SAID REACTION SECTION OF A DEPTH TO DEFINE A FREEBOARD SPACE WITHIN SAID REACTION SECTION, C. LIQUID FEED MEANS ADAPTED TO INTRODUCE A SOLUTION OF ALUMINUM NITRATE BENEATH THE SURFACE OF SAID FLUIDIZED BED, SAID LIQUID FEED MEANS COMPRISING A PLURALITY OF NOZZLE MEANS ADAPTED TO INTRODUCE SAID SOLUTION OF ALUMINUM NITRATE IN THE FORM OF ATOMIZED LIQUID DROPLETS INTO SAID BED PARTICLES AND BEING LOCATED AT AT LEAST TWO DIFFERENT BED LEVELS AND SPACED AROUND SAID BED IN EACH OF SAID LEVELS, AND MAINFOLD MEANS ADAPTED TO SUPPLY SAID SOLUTION OF ALUMINUM NITRATE TO SAID NOZZLE MEANS, D. HEAT TRANSFER FLUID INLET HEADER MEANS AND HEAT TRANSFER FLUID OUTLET HEADER MEANS POSITIONED WITHIN SAID FREEBOARD SPACE, E. A PLURALITY OF ELONGATED, SPACED APART U-SHAPED TUBING MEMBERS, EACH OF WHICH PROVIDES A FLUID CONNECTION BETWEEN SAID INLET AND OUTLET HEADER MEANS AND EXTENDS THROUGH SAID BED TO WITHIN A DISTANCE FROM SAID GRID PLATE SUFFICIENT TO PREVENT DIRECT IMPINGEMENT OF FLUIDIZING GAS, DELIVERED UNDER PRESSURE FROM SAID FLUIDIZING GAS CHAMBER THROUGH SAID GRID PLATE TO SAID BED, ONTO THE SURFACE OF SAID TUBING MEMBERS, SAID TUBING MEMBERS BEING SO POSITIONED WITHIN THE BED TO PREVENT DIRECT IMPINGEMENT OF SAID LIQUID ALUMINUM NITRATE FEED SOLUTION ONTO THE WALLS OF SAID TUBING MEMBERS, F. PIN MEANS MOUNTED ON SAID GRID PLATE AND ADAPTED TO MAKE A LOOSE FIT WITH COLLAR MEANS ATTACHED TO THE BOTTOM ENDS OF SAID TUBING MEMBERS THEREBY SUPPORTING SAID TUBING MEMBERS WHILE PERMITTING THERMAL EXPANSION AND CONTRACTION OF THE WALLS DEFINING SAID TUBING MEMBERS, G. MEANS TO WITHDRAW SOLID PRODUCT FROM SAID FLUIDIZED BED, H. MEANS TO WITHDRAW EFFLUET OFF-GASES FROM SAID EFFLUENT GAS CHAMBER, I. MEANS TO SEPARATE THE NITRIC ACID VAPOR FROM THE WATER VAPOR IN SAID EFFUENT GASES, J. MEANS TO SUPPLY A FLUIDIZING GAS TO SAID FLUIDIZING GAS CHAMBER, K. MEANS TO HEAT AND CIRCULATE A HEAT TRANSFER FLUID THROUGH SAID INLET HEADER MEANS, SAID TUBING MEMBERS AND SAID OUTLET HEADER MEANS, L. MEANS TO HEAT SAID SOLID PRODUCT TO REMOVE ANY RESIDUAL NITRATE VALUES THEREFROM TO PRODUCE ALUMINA PRODUCT, AND M. MEANS TO RECOVER THE NONCONDENSIBLE NITROGEN OXIDE GASES FROM SAID WATER VAPOR.

Claim 3

An apparatus in accordance with claim 1 including means to convert any gamma-alumina in said alumina product to alpha-alumina.

Claim 4

An apparatus in accordance with claim 2 wherein said means to convert gamma-alumina to alpha-alumina cOmprises means to calcine said alumina product.

Claim 5

An apparatus is accordance with claim 2 wherein said means to convert gamma-alumina to alpha-alumina comprises thermally insulated silo storage means.

Claim 6

A fluidized bed system adapted for decomposition of an aqueous solution of aluminum nitrate to form an alumina product and nitric acid, comprising in combination a. housing means defining therein a plurality of fluidized beds, each of said beds comprising a central reaction section, a fluidizing gas chamber below said reaction section and separated from said reaction section by a grid plate, and an effluent gas chamber above said reaction section; b. fluidizable bed particles in said reaction sections of each of said fluidized beds, said fluidizable bed particles being of a depth to define a freeboard space within each of said reaction sections; c. liquid feed means adapted to introduce a solution of aluminum nitrate in the form of atomized liquid droplets beneath the surface of each of said fluidized beds, each of said liquid feed means comprising a plurality of nozzle means, adapted to introduce said solution of aluminum nitrate in the form of atomized liquid droplets and being located at at least two different bed levels and spaced around said bed in each of said levels; and manifold means adapted to supply said solution of aluminum nitrate to said nozzle means; d. heat transfer fluid inlet header means and heat transfer fluid outlet header means positioned within said freeboard space in each of said fluidized beds; e. in each of said fluidized beds a plurality of elongated spaced apart U-shaped tubing members each of which provides a fluid connection betweeen said inlet and outlet header means and extends down through said bed to within a distance from said grid plate sufficient to prevent direct impingement of fluidizing gas, delivered under pressure from said fluidizing gas chamber through said grid plate to said bed, onto the surface of said tubing members, said tubing members being so positioned within the bed to prevent direct impingement of said liquid droplets of said aluminum nitrate feed solution onto the walls of said tubing members; f. pin means mounted on each of said grid plates for making a loose fit with collar means attached to the bottom ends of said tubing members thereby supporting said tubing members while permitting thermal expansion and contraction of the walls defining said tubing members; g. means to withdraw solid product from each of said fluidized beds; h. conduit means providing fluid communication between one of said fluidized beds and the other of said fluidized beds to serve as means to withdraw effluent off-gases from said effluent gas chamber of said one of said fluidized beds and to introduce the effluent off-gases from said one of said fluidized beds into the fluidizing gas chambers of said other of said fluidized beds as fluidizing gas for said other of said fluidized beds; i. means to supply steam as a fluidizing gas to said one of said fluidized beds; j. means to withdraw effluent off-gases from said other of said fluidized beds; and k. means to heat and circulate a heat transfer fluid through said inlet header means, said tubing members and said outlet header means of each of said fluidized beds.

Claim 7

A fluidized bed system adapted for decomposition of an aqueous solution of aluminum nitrate to form an alumina product and nitric acid, comprising in combination a. housing means defining therein a plurality of fluidized beds, each of said beds comprising a central reaction section, a fluidizing gas chamber below said reaction section and separated from said reaction section by a grid plate, and an effluent gas chamber above said reaction section; b. fluidizable bed particles in said reaction sections of each of said fluidized beds, said fluidizable bed particles being of a depth to define a freeboard space within each of said reaction sections; c. liquid feed means adapted to introduce a solution of aluminum nitrate in the form of atomized liquid droplets beneath the surface of each of said fluidized beds, each of said liquid feed means comprising a plurality of nozzle means, adapted to introduce said solution of aluminum nitrate in the form of atomized liquid droplets and being located at at least two different bed levels and spaced around said bed in each of said levels; and manifold means adapted to supply said solution of aluminum nitrate to said nozzle means; d. heat transfer fluid inlet header means and heat transfer fluid outlet header means positioned within said freeboard space in each of said fluidized beds; e. in each of said fluidized beds a plurality of elongated spaced apart U-shaped tubing members each of which provides a fluid connection betweeen said inlet and outlet header means and extends down through said bed to within a distance from said grid plate sufficient to prevent direct impingement of fluidizing gas, delivered under pressure from said fluidizing gas chamber through said grid plate to said bed, onto the surface of said tubing members, said tubing members being so positioned within the bed to prevent direct impingement of said liquid droplets of said aluminum nitrate feed solution onto the walls of said tubing members; f. pin means mounted on each of said grid plates for making a loose fit with collar means attached to the bottom ends of said tubing members thereby supporting said tubing members while permitting thermal expansion and contraction of the walls defining said tubing members; g. means to withdraw solid product from each of said fluidized beds; h. conduit means providing fluid communication between one of said fluidized beds and the other of said fluidized beds to serve as means to withdraw effluent off-gases from said effluent gas chamber of said one of said fluidized beds and to introduce the effluent off-gases from said one of said fluidized beds into the fluidizing gas chambers of said other of said fluidized beds as fluidizing gas for said other of said fluidized beds; i. means to supply steam as a fluidizing gas to said one of said fluidized beds; j. means to withdraw effluent off-gases from said other of said fluidized beds; and k. means to heat and circulate a heat transfer fluid through said inlet header means, said tubing members and said outlet header means of each of said fluidized beds.

Claim 8

An apparatus in accordance with claim 5 including l. means to heat said solid product to remove any residual nitrate values therefrom to produce alumina product; m. means to separate the nitric acid vapor from the water vapor in said effluent gases; and n. means to recover the noncondensible nitrogen oxide gases from said water vapor.

Claim 9

An apparatus in accordance with claim 5 wherein the sizes and capacities of said one of said fluidized bed and of said other of said fluidized beds are adjusted so that the amount and flow velocity of said effluent off-gases from said one of said fluidized bed are sufficient to fluidize said other of said fluidized beds.

Claim 10

An apparatus in accordance with claim 5 wherein said plurality of fluidized beds comprises three beds of substantially the same diameter and height.

Claim 11

An apparatus in accordance with claim 5 including means to convert any gamma-alumina in said alumina product to alpha-alumina.