Liquid purification or separation – Flow – fluid pressure or material level – responsive – Maintaining stream pressure or flow
Patent
1990-12-31
1992-11-03
Theisen, Mary Lynn
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Maintaining stream pressure or flow
210 98, 2101952, 210196, 210295, 2104161, 210418, 210900, B01D 6122, B01D 6100
Patent
active
051604299
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a piping system for supplying ultra-pure water to be used in large quantity in electronic industry such as semiconductor industry, or in biochemical and pharmaceutical industry.
In the past, a system as shown in FIG. 3 has been known as a piping system for supplying ultra-pure water for electronics industry, especially in the application for the manufacture of semiconductor integrated circuits.
According to such system, the primary pure water produced by a primary ultra-pure water producing system (not shown) is supplied to a circulation tank 102 through a primary pure water supply pipe 101. The primary water stored in the circulation tank 102 is pressurized by a pressure pump 103 and is purified through ultraviolet sterilizing unit (hereinafter referred as "UV sterilizing unit") 104, cartridge polishers 105, 106 and 107 and ultrafilter units 108 and 109. 122 represents a drain pipe for ultrafilter unit. The ultra-pure water thus purified is supplied to each of the user points 119, 120 and 121 through an outward pipe, connection pipes 113, 114 and 115 and branching valves 116, 117 and 118. After passing through connection pipes 113, 114 and 115, the ultra-pure water flows through a circulation route to return to the circulation tank 102 through a return pipe 112. The connection pipes 113, 114 and 115 are composed of upstream pipe sections 113-1, 114-1 and 115-1 and downstream pipe sections 113-2, 114-2 and 115-2.
FIG. 4 shows a piping system for supplying ultra-pure water of FIG. 3. 201 represents the entire ultra-pure water producing system. 131, 132 and 133 show the branching points of the connection pipes 113, 114 and 115 to the user points. The branching valves 116, 117 and 118 are integrally composed of the branching points 131, 132 and 133 respectively.
The ultra-pure water produced by such ultra-water producing unit is often supplied to the ultra-pure water using unit (hereinafter called as "user point", meaning the place where ultra-pure water is used). In a normal system, the number of the user points is extremely many, while FIG. 3 shows an example where 3 user points are provided.
However, in such piping system of conventional type, the quantity of ultra-pure water flowing in the outward pipe 110 is decreased when the number of the user points is increased, i.e. when the number of branching points is increased. On the contrary, the quantity of water in the return pipe 112 is increased when the number of the branching points is increased. Because the condition to use ultra-pure water at each user point is not constant, it has been difficult in the past to maintain the pressure between the outward pipe 110 and return pipe 112 of each of the connection pipes 113, 114 and 115 at constant level, and it has been impossible to supply a constant quantity of ultra-pure water to each of the user points at all times.
Also, in a conventional type piping system, the connection pipes 113, 114 and 115 have the same inner diameter upstream and downstream of the branching points. The branching valves 116, 117 and 118 are designed in such manner that, when they are opened, the pressure at the branching points 131, 132 and 133 is approximately equal to the atmospheric pressure. For example, in case the branching valve 117 is opened when ultra-pure water is used in the ultra-pure water using unit 120, the pressure at the branching point 132 is approximately equal to the atmospheric pressure.
On the other hand, the pressure of ultra-pure water flowing in the outward pipe 110 and the return pipe 112 is adjusted to the valve higher by 1-2 kg/cm.sup.2 than the atmospheric pressure in normal case. As the result, there occurs in the connection pipes 113, 114 and 115 the flow going from the outward pipe 110 to the branching point 132 and the flow going from the return pipe 112 to the branching point 132, and these flows are mixed and supplied to the ultra-pure water using unit. The ultra-pure water flowing from the return pipe 112 to the branching pipe 132 is t
REFERENCES:
patent: 4595498 (1986-06-01), Cohen et al.
patent: 4734201 (1988-03-01), Watanabe
Kawakami Michiya
Ohmi Tadahiro
Shibata Tadashi
Umeda Masaru
Kim Sun Uk
Ohmi Tadahiro
Theisen Mary Lynn
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