Abstract: The present invention provides a liquid concentration detecting method and a liquid concentration detecting apparatus in which light beams of at least two different wavelength bands having a central wavelength within a range of from 1.4 to 2.05 &mgr;m are irradiated on to a solution, and concentrations of at least two constituents contained in the solution are detected by detecting the amount of light transmitting through the solution relative to the light beams of each wavelength band. The present invention permits inline real-time detection at a high accuracy of concentrations of a plurality of constituents contained in a chemical solution used in a semiconductor manufacturing process or a liquid crystal substrate manufacturing process. Further, according to the present invention, it is possible to high-accuracy and high-reliability detection of the liquid concentration with a simple configuration.

Abstract: The present invention provides a liquid concentration detecting method and a liquid concentration detecting apparatus in which light beams of at least two different wavelength bands having a central wavelength within a range of from 1.4 to 2.05 &mgr;m are irradiated on to a solution, and concentrations of at least two constituents contained in the solution are detected by detecting the amount of light transmitting through the solution relative to the light beams of each wavelength band. The present invention permits inline real-time detection at a high accuracy of concentrations of a plurality of constituents contained in a chemical solution used in a semiconductor manufacturing process or a liquid crystal substrate manufacturing process. Further, according to the present invention, it is possible to high-accuracy and high-reliability detection of the liquid concentration with a simple configuration.

Abstract: A liquid concentration detecting apparatus which permits a real-time and high-accuracy detection of concentration of a liquid (particularly an etching or cleaning solution) used in a semiconductor plant, with a simple configuration at a low cost. The liquid concentration detecting apparatus 1 has a cell 2 to which a liquid is supplied, and a projecting section 4 and a receiving section 5 arranged opposite to each other in a direction at right angles to the axial line of the cell. A light of a prescribed wavelength is projected from this projecting section 4 through the liquid in the cell 2 to the receiving section 5, and the concentration of the liquid is determined by detecting the amount of light received by the receiving section.

Abstract: An electronic hygrometer and an electronic thermohygrometer both comprising oscillation means and digital operation processing means. The oscillation means of the hygrometer includes a square-wave pulse signal generator, a humidity sensor connected to the generator and which exhibits characteristics variable with the humidity change of the atmosphere, and a passive element connected to the generator and which forms a time constant circuit with the characteristics of the humidity sensor, the passive element being of a type different from the humidity sensor. The oscillation means produces square-wave pulse signals corresponding to changes in the characteristics of the sensor. The digital operation processing means of the hygrometer counts the frequency of the square-wave pulse signals output from the oscillation means and determines the humidity of the atmosphere on the basis of the counted value.

Abstract: A process for fabricating a humidity-sensing element comprises forming an electrode layer on at least one side of a ceramic substrate, applying to the electrode layer a humidity-sensitive paste containing a zirconia, zirconia-yttria, or yttria ceramic as a humidity-sensitive material, drying the coat, and then firing it at a temperature of 750.degree. to 870.degree. C. to form a humidity-sensing part.

Abstract: In a reactor for cracking heavy hydrocarbon oil through a fluidized bed of the particles of natural ores, coke-like materials are deposited on a top of the reactor or pipe inside surfaces of a transfer line from the reactor to a scrubber. To effectively scour out the deposited coke-like materials, particles of natural ores having a mean diameter of a few hundred .mu.m is made to be contained in an effluent gas from the top of reactor, passing through the transfer line at a concentration of 1 to 40 g/m.sup.3. The particles of natural ores have a good effect of scouring out the deposited coke-like materials and can keep the transfer line efficiently clean even with a small amount of the particles of natural ores, decreasing a pressure drop in the transfer line.

Abstract: In a reactor for cracking heavy hydrocarbon oil through a fluidized bed of particles of natural ores, coke-like materials are deposited on a top of the reactor or pipe inside surfaces of a transfer line from the reactor to a scrubber. To effectively scour out the deposited coke-like materials, particles of natural ores having a mean diameter of a few hundred .mu.m is made to be contained in an effluent gas from the top of reactor, passing through the transfer line at a concentration of 1 to 40 g/m.sup.3. The particles of natural ores have a good effect of scouring out the deposited coke-like materials and can keep the transfer line efficiently clean even with a small amount of the particles of natural ores, decreasing a pressure drop in the transfer line.