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US 6,444,014 B1Granted
VPSA process using adsorbent materials
AssigneePraxair Technology, Inc.
InventorsJoseph Timothy Mullhaupt, Frank Notaro
Life of this patent
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Abstract
The invention relates to the use of adsorbent materials that have been selected on the basis of their relationship between that material's intrinsic rate and equilibrium properties.
Claims19
A process for the separation of nitrogen from a feed gas including nitrogen, said process comprising:
- contacting the gas in an adsorption zone with an adsorbent that is equilibrium selective for nitrogen and adsorbing nitrogen on said adsorbent, wherein said adsorption zone comprises an equilibrium selective adsorbent material selected from the group consisting of A-zeolite, Y-zeolite, NaX, mixed cation X-zeolite, chabazite, mordenite, clinoptilolite, silica-alumina, alumina, silica, titanium silicates, phosphates and mixtures thereof;
- and wherein said adsorbent has properties defined by the hyperbolic function:
- (SCRR−0.22)*NML FoM≧2.5;
- wherein
- SCRR=RR*(dparticle)2;
- RR=ΔN2(YF, Y0)/(t2−t1);
- ΔN2(YF, Y0)=[N2 Loading at p, YF]−[N2 Loading at p, Y0] at 300K;
- YF, Y0, Y2 and Y1 are mole fractions in the gas phase, and t2 and t1 are the times corresponding to Y2 and Y1 in the concentration front;
- dparticle=the Ergun diameter of the adsorbent particle;
- NML FoM=[ΔN2(T,B)]*[αT(N2/O2)]2/[αB(N2/O2)] as measured at 300K;
- ΔN2(T,B)=[N2 Loading at pT, XT]−[N2 Loading at pB, XB];
- αT(N2/O2)=[XT(N2)/XT(O2)]/YT(N2)/YT(O2)];
- αB(N2/O2)=[XB(N2)/XB(O2)]/YB(N2)/YB(O2)];
- subscript T denotes the highest adsorption pressure, and subscript B denotes the lowest desorption pressure;
- XT and XB are mole fractions of the indicated molecules in the adsorbed phase at the pressure denoted by the subscript;
- and
- YT and YB are mole fractions of the indicated molecules in the gas phase at the pressure denoted by the subscript.
14 more elements
process for the selection of adsorbents for use in the separation of nitrogen from a nitrogen containing gas, said process comprising selecting adsorbents from the group consisting of A-zeolite, Y-zeolite, NaX, mixed cation X-zeolite, chabazite, mordenite, clinoptilolite, silica-alumina, alumina, silica, titanium silicates, phosphates and mixtures thereof;
- and wherein said adsorbent has properties defined by the hyperbolic function:
- (SCRR−0.22)*NML FoM≧2.5SCRR=RR*[dparticle]2
- RR=ΔN2(YF, Y0)/(t2−t1)
- ΔN2(YF, Y0)=[N2 Loading at p, YF]−[N2 Loading at p, Y0] at 300K;
- YF, Y0, Y2 and Y1 are mole fractions in the gas phase, and t2 and t1 are the times corresponding to Y2 and Y1 in the concentration front;
- dparticle=the Ergun diameter of the adsorbent particle;
- NML FoM=[ΔN2(T,B)]*[αT(N2/O2)]2/[αB(N2/O2)] as measured at 300K;
- ΔN2(T, B)=[N2 Loading at pT, XT]−[N2 Loading at pB, XB];
- αT(N2/O2)=[XT(N2)/XT(O2)]/[YT(N2)/YT(O2)];
- αB(N2/O2)=[XB(N2)/XB(O2)]/[YB(N2)/YB(O2)];
- T=the highest adsorption pressure;
- B=the lowest desorption pressure;
- XT and XB are mole fractions of the indicated molecules in the adsorbed phase at the pressure denoted by the subscript;
- and
- YT and YB are mole fractions of the indicated molecules in the gas phase at the pressure denoted by the subscript.
12 more elements
A process for the production of oxygen from air, comprising:
- contacting air in an adsorption zone with an adsorbent that is equilibrium selective for nitrogen and adsorbing nitrogen on said adsorbent, wherein said adsorption zone comprises an equilibrium selective adsorbent material whose intrinsic rate is correlated to that material's capacity.
A process for improving the performance of a given adsorbent material, said process comprising
- a) measuring said adsorbent's NML FoM equilibrium properties;
- b) solving the following equation for a minimum value of SCRR:
- (SCRR−0.22)*NML FoM≧2.5;
- wherein:
- SCRR=RR*(dparticle)2
- RR=ΔN2(YF, Y0)/(t2−t1)
- NML FoM=[ΔN2(T,B)]*[αT(N2/O2)]2/[αB(N2/O2)] as measured at 300 K;
- ΔN2(T,B)=[N2 Loading at pT, XT]−[N2 Loading at pB, XB];
- αT(N2/O2)=[XT(N2)/XT(O2)]/YT(N2)/YT(O2)];
- αB(N2/O2)=[XB(N2)/XB(O2)]/YB(N2)/YB(O2)];
- YF, Y0, Y2 and Y1 are mole fractions in the gas phase, and t2 and t1 are the times corresponding to Y2 and Y1 in the concentration front;
- dparticle=the Ergun diameter of the adsorbent particle;
- T=the highest adsorption pressure;
- B=the lowest desorption pressure;
- XT and XB are mole fractions of the indicated molecules in the adsorbed phase at the pressure denoted by the subscript;
- and
- YT and YB are mole fractions of the indicated molecules in the gas phase at the pressure denoted by the subscript;
- c) preparing a material having a measured SCRR equal to or greater than said minimum value of SCRR by modifying synthesis of said adsorbent material such that morphology of said material is modified so as to change said material's SCRR.
15 more elements
An apparatus for measuring the rate at which an adsorbable material is adsorbed by an adsorbent, said apparatus comprising:
- a) an adsorbent bed;
- b) a source of oxygen and means for providing said oxygen to said adsorbent bed;
- c) a source of air or synthetic air mixture containing only N2 and O2 and means for providing said air or synthetic air mixture to said adsorbent bed;
- d) an oxygen analyzer downstream of said adsorbent bed for measuring the concentration of oxygen;
- e) a flow meter downstream of said adsorbent bed for measuring the flow rate of oxygen.
2 more elements
Dependencies are inferred from the claim text.