摘要:
An improved method for cleaning heat exchangers, wherein a first liquid containing a cleaning agent is used to remove substantially all of the accumulated sludge and deposits from the surfaces of the heat exchanger, and a second liquid containing a cleaning agent is used to remove deposits from the crevice regions of the heat exchanger. The concentration of cleaning agent in the second liquid and/or the duration of exposure for the second liquid are preferably greater than those of the first liquid, because the risk of corrosion is reduced as a result of a lower concentration of ferric ions in the second liquid. Furthermore, improved crevice region cleaning is obtained with the second liquid because the available cleaning agent is not depleted by the large volume of sludge and deposits removed by the first liquid. Mechanical cleaning techniques such as pressure pulse cleaning may be utilized with either or both of the cleaning liquids. Additional liquids may be introduced into the heat exchanger to provide further cleaning action or to facilitate flushing of the previous cleaning liquids.
摘要:
A device for creating a corrosive condition and monitoring that condition, adapted for use in active fluid heat exchangers, has a sealed tube having corrosion sites spaced apart on its exterior. Structure positioned on the outside of the tube at the corrosion sites provide crevices for retaining corrosive sludges in contact with the corrosion sites. The interior of the tube is pressurized with a gas to stress the tube thereby accelerating corrosion of the surface. Heat is provided to the corrosion sites from within the tube when placed within a fluid reservoir, such as the secondary side of a fluid heat exchanger. The heat concentrates corrosive chemicals at the corrosion sites, also accelerating corrosion. Electronic probes can be mounted in proximity to the corrosion sites for real time monitoring of the progress of corrosion.
摘要:
An improved method for removing sludge and corrosion products from the interior of a heat exchanger vessel, such as a nuclear steam generator, which comprises the steps of generating a series of pressure pulses within a liquid chelate-containing chemical cleaning agent after the agent has been introduced into the interior of the vessel to create shock waves in the liquid for dislodging, dissolving and fluidizing sludge and corrosion products. The liquid chemical cleaning agent is removed from the vessel after only about 10 to 70 percent of what would have been its normal residence time without the pressure pulses. The method further includes the steps of simultaneously recirculating the chemical cleaning agent through a filter assembly during the pressure pulsing operation in order to remove fluidized sludge and corrosion products dislodged by the pressure pulsing, thereby affording them no opportunity to resettle back onto the surfaces of the heat exchanger vessel and interfere with the chemical cleaning of the vessel. The method reduces not only the time required for a particular chemical cleaning agent to effectively clean the vessel, but further reduces the number of times such chemicals need to be introduced into the vessel, which in turn results in the production of less radioactive liquid waste products.
摘要:
A method and apparatus for efficient branching within a central processing unit with overlapped fetch and execute cycles which optimizes the efficient fetching of instructions.
摘要:
A basic instruction for moving a string of bytes in a word has been devised. Because the operations in the instruction are basic, very few variations are necessary to accommodate diversity of lengths and variables. These operations are imbedded in a single code sequence; the compiler can therefore generate exactly the minimum sequence necessary to perform the operations and can precompute many of the operands at compile time, typically completing the instruction within a single cycle time. The control necessary to optimize the operations is then in the compiler instead of the hardware.
摘要:
A process for cleaning out deposits collected in the restricted areas of the secondary side of a steam generator of a nuclear power plant system, where the concentration of an aqueous organic cleaning agent solution is increased in the restricted areas, relative to the remainder of the solution. The solution is heated, at an initial pressure which prevents boiling of the solution, and the pressure is reduced to effect localized flashing and boiling of the solution in the restricted areas. After a period of time, the pressure is increased and the cleaning agent solution, containing solubilized deposits, is withdrawn from the secondary side of the steam generator. The heating temperature and pressure will vary depending upon the type of deposit to be removed, either ferrous-type or copper-type deposits.
摘要:
A battery powered hand-held calculator for performing arithmetic, triganometric and logarithmic functions and displaying the results thereof is provided with a clock mode which performs the function of a clock and displays real time or the function of a stopwatch and stores and displays the times at which recorded events have taken place.