摘要:
A beam or flow of a reactive or metastable precursor such as a hydride or organometallic compound is created, and this beam or flow is used to treat (e.g. dope or coat or otherwise modify) a substrate, e.g. an advanced material such as a semiconductor layer, a photovoltaic cell, or a solar cell. The beam or flow can also be directed into a storage zone so that the precursor or precursors can be collected for future use. The beam or flow is created in an apparatus comprising at least three zones. Zone 1 is irradiated with microwave energy to generate a reactive gas rich in free radicals (e.g. rich in H.sup.., CH.sub.3.sup.., etc.) zone 2 (downstream from zone 1) is substantially free of microwave energy and contains a target which is impinged upon by the free radicals and becomes a source of the precursor; zone 3 (downstream from zone 2) is where the precursors are either collected for storage or are used to treat the substrate. In a typical apparatus of this invention, a feed gas such as H.sub.2 or CH.sub.4 is introduced into an elongated tube 50 which communicates with a microwave cavity 57 containing a microwave plasma. A reactive gas containing free radicals (and perhaps some ions) flows from cavity (57 to target 61, where the free radicals react with the target to form the precursor (e.g. a hydride such as silane). When the precursor enters zone 3 it can treat an advanced material 73, e.g. by decomposing into Si+2H.sub.2. The Si is deposited on substrate 73 and the liberated H.sub.2 is pumped away. The pumping system also keeps the interior of the apparatus under subatmospheric pressure, e.g. 0.1 to 10 torr.
摘要:
The mechanical stress indicator includes two stress indicating rings disposed between engagable fasteners. The stress indicating rings can assume three distinct cooperative positions, corresponding to a less than optimally tight condition of the fastener, an optimum tightness condition and an overtight condition. When the fastener arrangement is in the less than optimally tight condition the mos visually predominant surfaces are of a first code, which can be a first color. When the fastener arrangement is tightened to an optimum tightness condition the stress indicator is deflected and the most visually predominant surfaces, which differ from those of the less than optimally tight condition, are of a second code, which can be a second color that corresponds with the optimum torque condition. When the fastener arrangement is tightened to an overtight condition the stress indicating rings are deflected to a third position wherein the most visually predominant surfaces are of a third code, which can be a third color corresponding to the overtight condition. The stress indicator can include a fixed non-deflectable base ring that is also coded with a color to cooperate with the deflectable rings. A deflector stub can be formed on one of the fastener members to facilitate deflection of the stress indicator rings from an optimum tightness condition to an overtight condition.
摘要:
A method is provided for evaluating simultaneously the effects of multiple, interdependent heat-exchanger degradation modes for a heat exchanger of a power plant in the context of a series of alternative heat-exchanger remediation strategies. The method includes calculating time-varying predicted future progressions of heat exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies, and calculating time-varying predicted future progressions of financial metrics describing the accumulated financial benefit of each of the strategies. The calculations may be provided in probabilistic terms. A strategy may then be chosen based, at least in part, on the calculated results.
摘要:
An improved scale conditioning composition and method is disclosed that results in improved dissolution and disruption of tube scale, hardened sludge and other deposits composed primarily of highly densified magnetite such as those found in heat exchange vessels, particularly steam generators. After treatment with the advanced scale conditioning composition, these magnetite rich deposits are more easily removed using known and commercially available high pressure hydro-mechanical cleaning techniques. The present invention further provides effective cleaning in a short period of time and at relatively low temperatures, while reducing the amount of waste produced and reducing the resulting corrosion of carbon and low alloy steel components within the steam generator during the cleaning process.
摘要:
An improved remotely-operated high-pressure water-jet sludge lancing system for removing sludge from the secondary side of steam generators, the system including an end effector and a deployment system. The end effector includes two diametrically opposed articulated nozzle heads having water jet nozzles attached thereto. The nozzle heads are pivotally mounted to respective pneumatic extension arm actuators that are accommodated in respective arms. The arms are attached in a collinear relation to opposing sides of a centrally located drive means, which allows for the rotational positioning of the nozzle heads. The deployment system for delivering and supporting the end effector includes a self-erecting load-bearing chain and a segmented support rail having a straight section and a curved section. The chain is suspended from the support rail by hangers and cylinder rollers.
摘要:
Disclosed are methods and apparatus for cleaning heat exchangers and similar vessels by introducing chemical cleaning solutions and/or solvents while maintaining a target temperature range by direct steam injection into the cleaning solution. The steam may be injected directly into the heat exchanger or into a temporary side stream loop for recirculating the cleaning solution or admixed with fluids being injected to the heat exchanger. The disclosed methods are suitable for removing metallic oxides from a heat exchanger under chemically reducing conditions or metallic species such as copper under chemically oxidizing conditions. In order to further enhance the heat transfer efficiency of heating cleaning solvents by direct steam injection, mixing on the secondary side of the heat exchanger can be enhanced by gas sparging or by transferring liquid between heat exchangers when more than one heat exchanger is being cleaned at the same time.
摘要:
An ultrasonic cleaning method for cleaning the film, scale and sludge from internal surfaces of tubes, tubesheets, tube support plates and channel heads of steam generators previously exposed to water or steam at temperatures of more than 200° C. introduces an ultrasonic transducer or transducer array into the steam generator and submerges the ultrasonic transducer and the surface to be cleaned in water or aqueous solution. Ultrasonic energy is introduced into the water at a power level of 20 watts/gallon or more and at frequencies of from 10 to 200 KHz. An array of transducers is employed to introduce 20 to 60 watts/gallon of water or more into the steam generator. In one practice, the transducer or transducer array is suspended in the steam generator. An array of transducers can be assembled (and later disassembled) in situ where individual transducers or small transducer subassemblies must introduced into the steam generator through small hand holes or other small diameter nozzles. In another practice, the ultrasonic transducer is moved through the water while introducing the ultrasonic energy into the water. Large amounts of ultrasonic energy can be introduced into the water and the energy nodes moved through the water so that the energy can efficiently penetrate into the interior rows of tubes and other internal structures.
摘要:
An apparatus for producing compound semiconductor thin films on substrates includes a reaction chamber wherein one or more constituents of semiconductor thin film is supplied as a gaseous species in a closed loop system. The apparatus includes hot and cold traps for isolating source materials from the reaction chamber and to provide for controlled delivery of the species. The hot and cold traps communicate with the reaction chamber through hot and cold legs to establish a closed loop recirculating flow. In a preferred embodiment, a thermosiphon provides the flow of gaseous species for formation of copper indium diselenide semiconductor thin films in a closed loop process.
摘要:
Disclosed are methods and apparatus for cleaning heat exchangers and similar vessels by introducing chemical cleaning solutions and/or solvents while maintaining a target temperature range by direct steam injection into the cleaning solution. The steam may be injected directly into the heat exchanger or into a temporary side stream loop for recirculating the cleaning solution or admixed with fluids being injected to the heat exchanger. The disclosed methods are suitable for removing metallic oxides from a heat exchanger under chemically reducing conditions or metallic species such as copper under chemically oxidizing conditions. In order to further enhance the heat transfer efficiency of heating cleaning solvents by direct steam injection, mixing on the secondary side of the heat exchanger can be enhanced by gas sparging or by transferring liquid between heat exchangers when more than one heat exchanger is being cleaned at the same time.
摘要:
The present invention provides methods and compositions useful for conditioning and removing solid deposits that have formed on or otherwise accumulated within one or more components including, for example, scale formed within a steam generating system. The aqueous cleaning compositions incorporate one or more quaternary ammonium hydroxides characterized by pKa values no less than about 13.5. These quaternary ammonium hydroxides may be used alone or in combination with one or more additives including, for example, chelating agents, reducing or oxidizing agents, pH adjustment agents, surfactants, corrosion inhibitors, complexing agents, dispersants and combinations thereof.