Abstract: An ultraviolet irradiation device that is used for a fluid to be irradiated having a low ultraviolet ray transmissivity, a spirally wound tube in which the fluid to be irradiated flows is supported and fixed, and an irradiation amount of ultraviolet rays with which the fluid is irradiated is increased. A tube 3 having ultraviolet ray transmitting property is spirally wound on an outer circumferential surface of a support pipe 5, a plurality of ultraviolet lamps 7 are disposed around an axis of the support pipe apart from the tube, an inner case 9 that supports the support pipe and that encloses the plurality of ultraviolet lamps is provided, and a fluid flows in the tube and is irradiated with ultraviolet rays. The tube which is a fluid channel is thereby fixed to the support pipe, so that breakage of the tube and the ultraviolet lamps 7 can be prevented.

Abstract: An ultraviolet irradiation device that is used for a fluid to be irradiated having a low ultraviolet ray transmissivity, a spirally wound tube in which the fluid to be irradiated flows is supported and fixed, and an irradiation amount of ultraviolet rays with which the fluid is irradiated is increased. A tube 3 having ultraviolet ray transmitting property is spirally wound on an outer circumferential surface of a support pipe 5, a plurality of ultraviolet lamps 7 are disposed around an axis of the support pipe apart from the tube, an inner case 9 that supports the support pipe and that encloses the plurality of ultraviolet lamps is provided, and a fluid flows in the tube and is irradiated with ultraviolet rays. The tube which is a fluid channel is thereby fixed to the support pipe, so that breakage of the tube and the ultraviolet lamps 7 can be prevented.

Abstract: Disclosed is a hard alloy with high hardness, high abrasion resistance, high corrosion resistance and high rigidity, which is excellent in performance in use for tools. The hard alloy contains more than 80% by weight of WC with less than 2 .mu.m of average particle size, more than 0.2% by weight and less than 2% by weight of Co and the remaining part of one or more metals, carbides, nitrides and carbonitrides of the metals in the IVa, Va and VIa families in the periodic table, such as 2.0 to 7.0% by weight of one or more of Mo and Mo.sub.2 C, and the alloy contains Co.sub.x W.sub.y C.sub.z in the sintered product. By the addition of Mo or Mo.sub.2 C and VC the growth of particles in the hard phase is inhibited and at the same time the wettability of WC--Co is increased.

Abstract: A process for preparing a carbon black which can control the particle size distribution and aggregate size distribution of the carbon black. This apparatus comprises a combustion chamber, a cylindrical throat more contracted than the combustion chamber, which is adapted for forming a plug flow of the hot gas, downstream of said throat, an expanding venturi portion downstream of said throat, and a carbon black reaction chamber; and a process comprising forming a plug flow of the hot gas in at least the cylindrical throat and the expanding venturi portion; and feeding a hydrocarbon material from hydrocarbon material spraying nozzles provided at two or more axially separate sites in the expanding venturi portion.

Abstract: An automatic air-fuel ratio control apparatus for use in a combustion system of a type in which combustion air is preheated, which is so arranged that a push rod depresses one end portion of a rocking lever in accordance with temperature of preheated combustion air and consequently the other end portion of the rocking lever depresses a valve member to correct pressure of working fluid for controlling a flow of fuel so as to obtain best air-fuel ratio, and further that a bearing member for pivotally supporting the rocking lever can be diagonally shifted to change the air-fuel ratio.