Abstract: Disclosed herein are methods of forming substantially crystalline, dense silicon carbide fibers from infusible polysilazane fibers by utilizing a single stage pyrolysis. The pyrolysis is performed using a continuous process in a single furnace with a constant atmospheric condition. Also disclosed are substantially crystalline, dense silicon carbide fibers formed by these methods.

Abstract: In a process and apparatus for treating produced water, the produced water flows through a series of treatment units. A portion of the produced water may by-pass one or more of the treatment units but the by-pass portion may be such that the treated water is still acceptable, for example for discharge or reuse. Concentrations of oil and grease, organic carbon, silica, pH or related parameters in the produced water may be monitored and used to control the process or apparatus. Control of the process may involve one or more of altering a by-pass portion, altering the addition of chemicals, and altering the operation of a unit process. The process may be controlled to respond to upset conditions, or such that the concentration of one or more limiting contaminants is near, but not over, a specified maximum for re-use or discharge.

Abstract: Methods for forming ceramic cores are disclosed. A ceramic core formed using the method of the present application includes a silica depletion zone encapsulating an inner zone. The inner zone includes mullite and the silica depletion zone includes alumina. The method includes heat-treating a ceramic body in a non-oxidizing atmospheric condition for an effective temperature and time combination at a pressure less than 10?2 atmosphere to form the silica depletion zone at a surface of the ceramic core.

Abstract: Methods for forming ceramic cores are disclosed. A ceramic core formed using the method of the present application includes a silica depletion zone encapsulating an inner zone. The inner zone includes mullite and the silica depletion zone includes alumina. The method includes heat-treating a ceramic body in a non-oxidizing atmospheric condition for an effective temperature and time combination at a pressure less than 10? atmosphere to form the silica depletion zone at a surface of the ceramic core.

Abstract: The present disclosure generally relates to a ceramic core comprising predominantly mullite, which is derived from a precursor comprising alumina particles and siloxane binders. Free silica is present in the ceramic body, but is largely unavailable for reaction with metal alloys used in investment casting. Methods of making cast metal articles are also disclosed.

Abstract: The present disclosure generally relates to a ceramic core comprising predominantly mullite, which is derived from a precursor comprising alumina particles and siloxane binders. Free silica is present in the ceramic body, but is largely unavailable for reaction with metal alloys used in investment casting. Methods of making cast metal articles are also disclosed.

Abstract: Systems and methods for removing organic contaminants from water may be used, for example, to treat produced water from a steam assisted heavy oil recovery operation. The treated produced water may be re-used to create steam. Alternatively, the produced water may be a blowdown stream treated to facilitate further treatment in a thermal crystallizer. The treatments may include pH adjustment or separating de-solubilized organics or both. Other treatments may include one or more of oxidation, sorption and biological treatments. The treatments may be used alone or in various combinations. One exemplary combination includes reducing the pH of produced water, separating de-solubilized organics from the produced water, and oxidizing the produced water or contacting the produced water with activated carbon.

Abstract: Processes for fabricating ceramic membranes include providing a porous substrate having at least one inner channel extending therethrough and having surfaces defined by porous walls, depositing a coating slurry on surfaces of the inner channel(s), and sintering. Sintering temperatures for the processes range from about 400° C. to 800° C. Coating slurries for use in the processes include a boehmite sol and a colloidal suspension of porous alumina particles.

Abstract: Systems and methods for removing organic contaminants from water may be used, for example, to treat produced water from a steam assisted heavy oil recovery operation. The treated produced water may be re-used to create steam. Alternatively, the produced water may be a blowdown stream treated to facilitate further treatment in a thermal crystallizer. The treatments may include pH adjustment or separating de-solubilized organics or both. Other treatments may include one or more of oxidation, sorption and biological treatments. The treatments may be used alone or in various combinations. One exemplary combination includes reducing the pH of produced water, separating de-solubilized organics from the produced water, and oxidizing the produced water or contacting the produced water with activated carbon.

Abstract: A method for ammonia synthesis using a water-gas shift membrane reactor (WGSMR) is presented. The method includes carrying out a water-gas shift reaction in the WGSMR to form a first product stream and a carbon dioxide (CO2) stream, wherein the first product stream includes nitrogen (N2) and hydrogen (H2), and a molar ratio of H2 to N2 in the first product stream is about 3. The method further includes separating at least a portion of the residual CO2 in the first product stream in a CO2 separation unit to form a second product stream, and separating at least a portion of the residual CO2 and carbon monoxide (CO) in the second product stream in a methanator unit to form a third product stream. The method further includes generating an ammonia stream from the third product stream in an ammonia synthesis unit. A system for ammonia synthesis is also presented.

Abstract: A hybrid multichannel porous structure for processing between two fluid streams of different compositions includes a housing and one or more structures disposed within the cavity of the housing in a shell and tube configuration. Each structure includes a body made of a porous, inorganic material and a plurality of channels for processing an optional sweep stream. Each channel is coated with a membrane layer. A feed stream introduced into the housing is in direct contact with the structures such that a gas selectively permeates through the body and into the channels. The gas combines with the sweep stream to form a permeate that exits from each channel. The remaining feed stream forms a retentate that exits from the housing. The feed stream may consist of syngas containing hydrogen gas and the sweep stream may contain nitrogen gas. A power plant that incorporates the hybrid structure is disclosed.

Abstract: A free-standing zeolite membrane and a zeolite membrane supported on a support structure are disclosed. The free-standing zeolite membrane is fabricated by mixing zeolite particles and an optional inorganic binder, forming a green body, and sintering the green body at a sufficiently low temperature so as to prevent damage to the gas selectivity properties of the zeolite particles. The supported composite zeolite membrane is fabricated by mixing a sacrificial binder, an optional inorganic binder, boehmite sol and zeolite particles to form a slurry. The slurry is then coated onto a porous support structure, dried and sintered at a sufficiently low temperature so as to prevent damage to the gas selective properties of the zeolite particles. In both membranes, the zeolite particles span the entire thickness of the membrane to provide a high selectivity path for the flow of gas to pass therethrough.

Abstract: A porous membrane structure is disclosed, which includes a porous substrate, a mesoporous, aluminum oxide layer disposed on the substrate; and a relatively thin, continuous, microporous barrier layer disposed on the mesoporous aluminum oxide layer, also formed from aluminum oxide. The membrane is capable of improving hydrogen selectivity within a gas stream, e.g., a synthesis gas composition. Membrane supports containing these structures are also described, as well as gas separation modules, and related processes. Power plants which incorporate the gas separation modules are also disclosed herein.

Abstract: A syngas cleanup section includes a water-gas shift reactor, a first operation unit and a second operation unit. The first operation unit includes a high permeance membrane with H2/CO2 selectivity in flow communication with the water-gas shift reactor to provide a H2-rich permeate stream and an H2-poor retentate stream. The second operation unit recovers H2 and CO from the retentate stream to produce a single, CO2-rich product stream, the entire content of which has a minimum pressure of at least about 10.0 bar. In one embodiment, the second operation unit includes a membrane with Knudsen selectivity for permeating H2, CO and CO2. In this embodiment, the permeate streams are combined to produce a H2 and CO-rich fuel stream used by a combined cycle power generation unit to produce electricity, and the retentate stream is sent to a catalytic oxidation unit to produce the CO2-rich product stream. In another embodiment, the second operation unit is the catalytic oxidation unit.

Abstract: A hybrid multichannel porous structure for processing between two fluid streams of different compositions includes a housing and one or more structures disposed within the cavity of the housing in a shell and tube configuration. Each structure includes a body made of a porous, inorganic material and a plurality of channels for processing an optional sweep stream. Each channel is coated with a membrane layer. A feed stream introduced into the housing is in direct contact with the structures such that a gas selectively permeates through the body and into the channels. The gas combines with the sweep stream to form a permeate that exits from each channel. The remaining feed stream forms a retentate that exits from the housing. The feed stream may consist of syngas containing hydrogen gas and the sweep stream may contain nitrogen gas. A power plant that incorporates the hybrid structure is disclosed.

Abstract: The present invention concerns a method of reducing fouling of ceramic membranes by adding an effective amount of a tannin polymer to SAGD process water. Additionally, a cationic and/or an anionic flocculant can also be added to treat the process water. Once the process water is treated, the solids are then separated out and the resulting clean process water is then passed through a ceramic membrane. Typically, the tannin polymer used in treating the process water is comprised of a Mannich reaction product of an amine, an aldehyde, and a tannin. The components are reacted at an acidic pH wherein the molar ratio of amine to tannin present is from about 1.5:1-3.0:1. Exemplary tannin/amine/formaldehyde compounds include tannin/melamine/formaldehyde polymers, and tannin/monoethanolamine/formaldehyde polymers.

Abstract: In a process and apparatus for treating produced water, for example for re-use in an oil or bitumen extraction operation of for treating frac water, the produced water flows through a series of treatment units. A portion of the produced water may by-pass one or more of the treatment units but the by-pass portion may be such that the treated water is still acceptable, for example for discharge or reuse. Concentrations of oil and grease, organic carbon, silica, pH or related parameters in the produced water may be monitored and used to control the process or apparatus. Control of the process may involve one or more of altering a by-pass portion, altering the addition of chemicals, and altering the operation of a unit process. The process may be controlled to respond to upset conditions, or such that the concentration of one or more limiting contaminants is near, but not over, a specified maximum for re-use or discharge.

Abstract: A method of forming an oxide coating for reducing the accumulation of radioactive species on a metallic surface exposed to fluids containing charged particles is disclosed. The method includes preparing an aqueous colloidal suspension containing about 0.5 to about 35 weight percent of nanoparticles that contain at least one of titania and zirconia, and about 0.1% to about 10% 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (C7H14O5) or polyfluorosufonic acid in water, depositing the aqueous colloidal suspension on the metallic surface, drying the aqueous colloidal suspension to form a green coating, and then heating the green coating to a temperature of up to 500° C. to densify the green coating to form an oxide coating having a zeta potential less than or equal to the electrical polarity of the charged particles so as to minimize deposition of the charged particles on the metallic surface. The nanoparticles have a diameter of up to about 200 nanometers.

Abstract: In some embodiments, the present invention is directed to methods of making structures with complex functional architectures, where such structures generally comprise at least two mesoporous regions comprising different chemical activity, and where such methods afford spatial control over the placement of such regions of differing chemical activity. In some embodiments, the present invention is also directed to the structures formed by such methods, where such structures are themselves novel.

Abstract: Processes for fabricating ceramic membranes include providing a porous substrate having at least one inner channel extending therethrough and having surfaces defined by porous walls, depositing a coating slurry on surfaces of the inner channel(s), and sintering. Sintering temperatures for the processes range from about 400° C. to 800° C. Coating slurries for use in the processes include a boehmite sol and a colloidal suspension of porous alumina particles.