Esposito W.R.,Princeton University |
Esposito W.R.,Praxair Inc. |
Floudas C.A.,Princeton University
Journal of Global Optimization | Year: 2015
The reactor network synthesis problem involves the simultaneous determination of the structure and operating conditions of a reactor system to optimize a given performance measure. This performance measure may be the yield of a given product, the selectivity between products, or the overall profitability of the process. The problem is formulated as a nonlinear program (NLP) using a superstructure based method in which plug flow reactors (PFRs) in the structure are modeled using differential-algebraic equations (DAEs). This formulation exhibits multiple local minima. To overcome this, a novel deterministic global optimization method tailored to the special structure and characteristics of this problem will be presented. Examples of isothermal networks will be discussed to show the nature of the local minima and illustrate various components of the proposed approach. © 2002Kluwer Academic Publishers
Praxair Inc. | Date: 2012-10-12
Disclosed are methods and apparatus for forming frozen foam products, including edible products, using air or gases or gas mixtures having an average molecular weight larger than that of air, wherein the products contain bubbles having a reduced average size preferably in a narrow size range.
Praxair Inc. | Date: 2012-10-04
A portable medical gas cylinder cart is disclosed. The portable medical gas cylinder cart comprises: (i) a moveable base having a forward section and an back section, the moveable base being supported above ground level with a plurality of wheels, casters or other moveable support structures; (ii) a front panel attached to the moveable base proximate the forward section that extends vertically upward from the base to hide the gas cylinders from view; (iii) a main body attached to the back section of the moveable base; and (iv) one or more adjustable gas cylinder shelves connected to the main body and adapted to hold one or more gas cylinders in a vertical upright orientation behind the front panel. Each of the adjustable gas cylinder shelves includes a cylinder platform, housing, and retention strap or belt as well as a lift mechanism or jack that is adapted to raise or lower the cylinder platform to and from the ground level below the base of the cart to facilitate loading and unloading of the gas cylinders onto the cylinder platform.
Praxair Inc. | Date: 2012-05-23
The present invention provides a method and apparatus for separating air and generating electrical power. A compressed air stream produced in a main air compressor is introduced into an air separation unit that cryogenically rectifies the air into component products. During turndown conditions of the air separation unit, a combustion air stream formed from all or part of the compressed air stream is introduced into a combustor in which a fuel is combusted to produce a heated and pressurized combustion stream. Such stream is introduced to a turbine connected to an electrical generator to generate electrical power. The combustion air stream can be saturated with moisture to increase power output. Further, the combustion air stream can also be preheated with an exhaust of a gas turbine.
Praxair Inc. | Date: 2013-11-01
This invention relates to high purity yttria or ytterbia stabilized zirconia powders comprising from about 0 to about 0.15 weight percent impurity oxides, from about 0 to about 2 weight percent hafnium oxide (hafnia), from about 6 to about 25 weight percent yttrium oxide (yttria) or from about 10 to about 36 weight percent ytterbium oxide (ytterbia), and the balance zirconium oxide (zirconia). Thermal barrier coatings for protecting a component such as blades, vanes and seal surfaces of gas turbine engines, made from the high purity yttria or ytterbia stabilized zirconia powders, have a density greater than 88% of the theoretical density with a plurality of verticalzA macrocracks homogeneously dispersed throughout the coating to improve its thermal fatigue resistance.