Nozzle cap, nozzle device provided with such cap, and spraying method of chemical solution

A nozzle cap to be used for a nozzle device for spraying a chemical solution to wet paper, wire, felt, press rollers, dryer rollers, canvas or guide rollers in a paper machine, comprising:

• an air cap part that is provided with a first base part having a cylinder shape, the first base being constituted by a lid part and a side wall part wherein a nozzle hole that penetrates the first base part is formed substantially in the center of the first base part;
• and
• a liquid cap part that is provided with a second base part having a disc-shape with a rib part formed so as to be freely detachably fitted to the first base part and a protruding part which is formed substantially in the center of the second base part so as to protrude toward the first base part wherein a flow passage for circulating a chemical solution therethrough is formed in the protruding part, and a plurality of chemical solution spraying air holes for circulating air therethrough are formed on the second base part in a manner so as to surround the protruding part, wherein
• a space is formed between the first base part and the second base part by the first base part and the second base part being fitted to each other,
• a chemical solution is flowed in the space from the protruding part, and air is flowed in the space from the chemical solution spraying air holes so that the chemical solution from the nozzle holes is sprayed by the air from the space,
• the lid part has a lower surface having a plane shape and an upper surface that faces in an opposite direction from the lower surface,
• a small diameter part is formed on the upper surface of the lid part wherein the small diameter part has a disc shape with a diameter that is smaller than that of the first base part, and is disposed substantially in the center of the first base part and the small diameter part,
• the nozzle hole is formed so as to penetrate the first base part and the small diameter part,
• the upper surface of the lid part is formed into a taper shape so as to be recessed in the center,
• the air flowed in the space through the chemical solution spraying air holes is made to collide with the lower surface of the lid part through the space.