System for automatically feeding chemical liquids to cooling towers

A system for automatically feeding a chemical liquid to a cooling tower includes a water reservoir for storing water circulating through the cooling tower, a water feeding pipe extending into said water reservoir, a float valve provided in a passage of said water-feeding pipe, which is actuated in response to a variation in a water level in said water reservoir to open or close said passage, a means for increasing the flow rate of water flowing through said passage to inject water from a discharge port at the time when said float valve opens, a negative pressure generating chamber located in said passage and defined by said injection of water and a chemical liquid pipe in communication with said negative pressure generating chamber. A chemical liquid in the chemical liquid pipe is injected with water from the discharge port through the negative pressure generating chamber under the action of a negative pressure generated therein.

BACKGROUND OF THE INVENTION 
1 Field of the Invention 
The present invention relates to a system for automatically feeding a 
chemical liquid to water circulating through a heat exchange circuit in a 
cooling tower so as to prevent red rust and/or fur from occurring in the 
circulating water. 
2 Statement of the Prior Art 
Such systems heretofore available in the art are broken down into large, 
medium and small sizes, and all rely upon automatic water-feeding means 
comprising a float valve or the like provided in a water reservoir, which 
is actuated to sense a reduction in a water level therein and return the 
water level to the predetermined level so as to constantly maintain a 
given amount of water circulating through a heat exchange circuit in a 
cooling tower. 
In the system of a large size, an electrically operated pump in operative 
association with such automatic water-feeding means is actuated to feed 
the predetermined amount of a chemical liquid on regular or automatic 
basis. 
In the systems of medium and small sizes, however, it is still required for 
maintenance workers to feed a chemical liquid in a manual manner. 
With the large-sized system it is possible to regularly feed a specific 
quantity of a chemical liquid to a water reservoir in which circulating 
water is stored. However, additional provision of an electrically operated 
pump needs additional facilities and costs. On the other hand, the medium- 
and small-sized systems are now under pressure of increased initial 
investment. 
Of the medium- and small-sized systems, some systems relying upon 
maintenance workers are inexpensive as compared with systems relying upon 
electrically operated pumps. Since cooling towers are generally installed 
on elevated spots such as the roofs of high buildings, however, not only 
is feeding work dangerous but also difficulty is encountered in regular 
feeding of a constant amount of a chemical liquid due to the need of man 
power. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide a system which can 
make use of a simple automatic water feeding means known in the art to 
automatically feed the predetermined amount of a chemical liquid depending 
upon the amount of water supplied during automatic circulating water 
feeding, whereby the predetermined porportion of a chemical liquid is 
always maintained in water circulating through a heat exchange circuit. 
A second object of the present invention is to provide a system which is of 
a very simple and inexpensive structure and can be easily attached to an 
existing cooling tower with no need of using costly units such as 
electrically operated pumps, power sources or other power. 
According to the present invention, the above objects are achieved by the 
provision of a system for automatically feeding a chemical liquid to a 
cooling tower which includes a water reservoir for storing water 
circulating through the cooling tower, a water feeding pipe extending into 
said water reservoir, a float valve provided in a passage of said 
water-feeding pipe, which is actuated in response to a variation in a 
water level in said water reservoir to open or close said passage, a means 
for increasing the flow rate of water flowing through said passage to 
inject water from a discharge port at the time when said float valve 
opens, a negative pressure generating chamber located in said passage and 
defined by said injection of water and a chemical liquid pipe in 
communication with said negative pressure generating chamber, a chemical 
liquid in said chemical liquid pipe being injected with water from said 
discharge port through said negative pressure generating chamber under the 
action of a negative pressure generated in said negative pressure 
generating chamber.

DETAILED DESCRIPTION OF THE INVENTION 
For a better understanding of the present invention, the present invention 
will now be described with reference to one illustrated embodiment. 
There is provided a water reservoir A for storing water circulating through 
a cooling lower. Disposed within the water reservoir A is a main water 
feeding pipe K.sub.0 from which two water-feeding pipes K.sub.1 and 
K.sub.2 are branched. Each of the pipes K.sub.1 and K.sub.2 is provided 
with a float valve f', f, respectively. One float valve f communicates on 
its outlet side with a vacuum (negative pressure) generating chamber 3 
through a Venturi tube 1, which chamber is provided with a discharge port 
2. 
Outside the water reservoir A, there is a chemical liquid tank 4, which in 
turn communicates with a guide passage 5 via a pipe 4a. That guide passage 
communicates with the negative pressure generating chamber 3. A check 
valve 6 is provided on the guide passage 5, and a differential flow member 
7 is located on the side of the Venturi tube 1 in the negative pressure 
generating chamber 3. A valve 8 is also provided for the flow regulation 
of a chemical liquid. 
In the system of the above structure, water is fed to the water reservoir A 
through the pipe K.sub.1 and the float valve f'. 
More specifically, when the water level in the water reservoir A lowers 
until the float valve f' opens, the water is fed to the water reservoir A 
through the water-feeding pipe K.sub.1. At the same time, the float valve 
f of the water-feeding pipe K.sub.2 opens, and the water leaving the 
outlet side of the float valve f passes through the Venturi tube 1 wherein 
its flow rate is so increased that it is injected into the water reservoir 
from the discharge port 2 of the differential flow member 7. By such 
injection of water, a negative pressure is generated in the negative 
pressure generating chamber 3, so that the check valve 6 opens to suck a 
chemical liquid from the tank 4 to the chamber 3 and feed it from the 
discharge port 2 into the water tank. 
Since the amount of water in the water-feeding pipe K.sub.1 is larger than 
that in the water-feeding pipe K.sub.2, the float valve f' closes upon the 
water level in the water reservoir rising to the predetermined level, so 
that the water feeding is stopped simultaneously with closing of the float 
valve f, thus resulting in the feeding of the chemical liquid being 
stopped. 
According to the automatic chemical liquid-feeding system according to the 
present invention, a chemical liquid is sucked and fed into the water 
reservoir under the action of a negative pressure generated by the 
injection of a part of water fed into the water reservoir. Thus, 
considerable reductions in the initial investment are achievable as 
compared with a means for feeding a chemical liquid with the use of a 
pump. 
Of the two water-feeding pipes, one pipe serves to feed water into the 
water reservoir and the other functions to generate a negative pressure 
for feeding a chemical liquid. It is thus possible to keep constant the 
concentration of a chemical liquid in the water reservoir with no fear of 
feeding the chemical liquid in excess, and to make maintenance and control 
extremely easy. 
Moreover, the present invention can be easily carried out with some 
modifications of a water-feeding system of an existing water reservoir. 
It is understood that the above described embodiment is simply illustrative 
of the application of principles of the invention and many other 
modifications may be made without departing from the spirit and scope of 
the invention.