U.S. patent number 3,857,551 [Application Number 05/372,366] was granted by the patent office on 1974-12-31 for device to dampen fluctuations in the concentration of a substance in a flowing stream of fluid.
This patent grant is currently assigned to NUS Corporation. Invention is credited to Joseph C. Troy.
United States Patent |
3,857,551 |
Troy |
December 31, 1974 |
DEVICE TO DAMPEN FLUCTUATIONS IN THE CONCENTRATION OF A SUBSTANCE
IN A FLOWING STREAM OF FLUID
Abstract
A process for smoothing out or damping concentration
fluctuations of a substance in a fluid stream comprising dividing
the stream into a number of substreams, feeding each of the
substreams to a common point while introducing different time
delays of arrival of each substream at the common point and then
recombining the substreams into the single larger stream again. An
apparatus for performing the above process comprising a combination
of means capable of dividing the influent stream into a number of
substreams, means capable of imparting different time delays to
each substream for arrival at some common point and means for
recombining the substreams.
Inventors: |
Troy; Joseph C. (Pittsburgh,
PA) |
Assignee: |
NUS Corporation (Rockville,
MD)
|
Family
ID: |
23467830 |
Appl.
No.: |
05/372,366 |
Filed: |
June 21, 1973 |
Current U.S.
Class: |
366/336;
366/341 |
Current CPC
Class: |
B01F
5/064 (20130101) |
Current International
Class: |
B01F
5/06 (20060101); B01f 015/02 () |
Field of
Search: |
;259/4,18,36,107,108
;138/38 ;137/3,4,5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jenkins; Robert W.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn &
Macpeak
Claims
What is claimed is:
1. An apparatus for damping variable concentrations of a substance
in a liquid stream, said apparatus comprising:
a triangular-shaped liquid container,
means for feeding said liquid stream into said liquid container
including a first, inlet manifold located along the hypotenuse of
said triangle,
means including said first inlet manifold for dividing said stream
into a plurality of substreams, and
mean for collecting said substreams at a common point comprising a
second, liquid outlet manifold located along one of the opposite
sides of said triangle;
whereby, said substreams dividing at said first inlet manifold and
being collected by said outlet manifold at said hypotenuse and said
side opposite thereto, respectively, imparts time delays to each
substream for arrival at said common point to provide a single
liquid stream which has a substantially constant concentration of
said substreams which is substantially lower than the peak or
highest concentration of said substreams in said stream prior to
treatment with said apparatus.
2. An apparatus as claimed in claim 1, wherein said triangular
shaped container comprises a basin, wherein said first, inlet
manifold comprises a first trough along the hypotenuse of the
triangular shaped basin, and said second, outlet manifold comprises
a second trough located along one of the opposite sides of said
triangular shaped basin; whereby, said basin imparts time delay to
said liquid stream which divides into a plurality of substreams and
moving from one trough to the other with said trough located along
said opposite side acting to recombine said substreams at a common
point to provide a single stream which has a substantially constant
concentration of said substance which is substantially lower than
the peak or highest concentration of said substance in said stream
prior to treatment with said apparatus.
3. An apparatus for damping variable concentrations of a substance
in a liquid stream, said apparatus comprising:
means capable of dividing said stream into a plurality of
substreams;
means for feeding each of said substreams to a common point;
means for imparting time delays to each substream for arrival at
said common point; and
means for recombining said substreams at said common point to
provide a single stream which has a substantially constant
concentration of said substance which is substantially lower than
the peak or highest concentration of that substance in said stream
prior to treatment with said apparatus,
said apparatus being rectangular in form and including a trough
disposed along the diagonal of said rectangle, with said fluid
flowing over both sides of said trough and toward the two sides of
said rectangle opposite said diagonal,
and wherein means for collecting said substreams at said common
point comprises troughs disposed along said two opposite sides and
meeting at their intersection.
4. An apparatus for damping variable concentrations of a substance
in a liquid stream, said apparatus comprising:
means capable of dividing said stream into a plurality of
substreams;
means for feeding each of said substreams to a common point;
means capable of imparting time delays to each substream for
arrival at said common point; and
means for recombining said substreams at said common point to
provide a single stream which has a substantially constant
concentration of said substance which is substantially lower than
the peak or highest concentration of said substance in said stream
prior to treatment with said apparatus;
and wherein, said apparatus is in the form of a circular tank and
said means capable of dividing said liquid stream into a plurality
of substreams comprises an inlet pipe for feeding said liquid
stream into said circular tank at a point off-center thereof, and
said means for collecting said plurality of substreams at said
common point comprises a trough surrounding the circumference of
said circular tank on the inside thereof such that the fluid flows
from said inlet pipe outwardly toward the circumference of the
circular tank and is collected within said trough.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device, termed an equalization
basin or equalization tank, designed to smooth out or dampen
fluctuations in concentration of a substance in a fluid system. In
addition, the present invention also relates to a process for
accomplishing the same result.
2. Description of the Prior Art
Obviously, in fluid systems where a constant concentration of a
substance in a fluid is desired or necessary, fluctuations in the
concentration of the substance in the fluid are undesirable or even
potentially harmful. As an example, if the salt concentration in a
liquid varied with time from 1 to 3 pounds per gallon with a mean
value of 2 pounds per gallon over a long period of time, the
perfect equalization device would accept this varying concentration
as an input, and deliver liquid at a constant effluent
concentration of 2 pounds per gallon. Such a perfect equalization
device is not possible since it would have to be of infinite size.
The best known and easiest to calculate practical equalization
device for fluid systems is a "complete mix basin." This device
consists of a pond or tank with a large, powerful mixer in it.
The term "complete mix" implies that the contents of the tank or
pond are uniform at every point and equal to the effluent
concentration. The influent enters through a pipe at one side and
is instantly mixed with the entire contents of the tank or pond. It
can be shown mathematically that the rate of change of
concentration of the effluent with respect to time is slower than
the rate of change of the influent concentration with respect to
time, and that the magnitude of the change in the concentration of
the effluent is proportionately less than the magnitude of the
change of concentration of the influent by the amount that the rate
of change of effluent concentration is slower than the rate of
change of influent concentration. The ratio of the two rates of
change and the two magnitudes of change is a function of the
holding time of the complete mix equalization device.
U.S. Pat. No. 3,404,869 (Harder) discloses an interfacial surface
generator, i.e., a mixing device, or static mixer which consists of
a number of chambers having two or more inlets and two or more
outlets, the inlets and outlets being noncoplanar and the planes
intersecting an axis of flow. The device mixes the incoming fluid
in such a manner that each of the outlet conduits contains a
portion of the material from each of the inlet conduits.
Other known mixing devices are disclosed in the following U.S. Pat.
Nos.: 3,291,456; 3,306,587, and 3,547,410.
The primary difficulty of the prior art devices and processes is
that their efficiency is unacceptable while some, in addition,
require complex apparatus and high energy inputs to achieve good
results.
It is therefore a primary object of the present invention to
provide a simple and efficient process for damping fluctuations in
concentration of a substance in a fluid without the above
disadvantages.
It is a further object of the present invention to provide a simple
device by which such a process can be performed.
Other objects, features and advantages will become apparent from
the ensuing description.
SUMMARY OF THE INVENTION
The process of the invention comprises:
1. dividing a stream of fluid containing a substance (whose
concentration fluctuations in the fluid one wishes to dampen) into
a number of substreams;
2. feeding each of the resulting substreams to a common point and
introducing time delays of arrival of each substream at the point
with each time delay of arrival being different for each substream;
and
3. recombining the substreams into the single larger stream
again.
The present invention also relates to an apparatus for performing
the above process. Generally, the apparatus comprises a combination
of means capable of dividing the influent stream into a number of
substreams, means capable of imparting different time delays to
each substream for arrival at some common point and means for
recombining the substreams. Specific processes and apparatus will
be discussed hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 represent simple devices which explain the theory of
the present invention.
FIGS. 3 through 7 show possible shapes of devices which may be
employed in the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is applicable to any fluid (gas and liquid)
stream containing a foreign substance whose concentration gradient
may vary with time or, generally, whose characteristic
manifestations one wishes to equalize. Examples of the foreign
substance are dissolved salt, dissolved alcohol, emulsified
lubricating oil, fine suspended particles of ore, etc.; i.e.,
anything that may be dissolved in, suspended in, or generally
"carried by" a fluid stream. Alternatively, the temperature of the
fluid stream may vary with time, and the present invention is
applicable to "equalizing" such a stream. Similar applications will
become apparent to those skilled in the art.
Applying the above basic principle to a stream of blue water which
suddenly turns red for a 2 minute period and then back to blue
again, gives the following results. Assume that the main stream is
divided into five substreams in the equalization device and that
the time delay of arrival at the designated common point of the
first substream is zero, of the second substream 2 minutes, of the
third substream is 4 minutes, of the fourth is 6 minutes, and of
the fifth is 8 minutes.
When the red slug comes along, the first substream will start to
run red at once and will run red for 2 minutes (the length of the
red pulse), but the other four streams will still be running blue
because of the time delay. Since only one of five streams is red,
the concentration of red in the effluent from the device will be
only 20 percent of the concentration in the input stream.
At the end of the first two minutes, the first substream will start
to flow blue again, but the second one (two minute time delay) will
start to flow red. Substreams 3, 4 and 5 will still be blue because
of their longer time delays so the concentration of red in the
effluent will continue at 20 percent of the influent pulse
value.
It can be seen that this situation will repeat itself across all
five substreams. In this case, the device has taken an input pulse
of 2 minutes duration and spread it out as an output pulse of only
20 percent of the initial concentration, but 5 times as long in
duration.
The above example is simplistic in nature for purposes of
illustration only. In actuality, the influent stream need not be
divided into a discrete number of individual substreams and treated
separately and finally recombined. Rather, the influent stream
enters the device as a single stream, but the geometry of the
device in effect divides the influent stream into what can be
considered as a very large number of substreams with the difference
in time delay of arrival at the common point becoming extremely
small. To illustrate the point, refer to FIG. 1, which
schematically shows a simple form of a device which accomplishes
the desired results of the present invention. The flow of fluid
through the device is indicated by the arrows. The fluid enters the
device via pipe 1 and then flows into a manifold 2, from which it
is divided into three separate streams designated 3, 4, and 5 in
the Figure. These three streams are again recombined in exit
manifold 6 and the fluid leaves the device via exit pipe 7.
Assuming the concentration of a substance in the fluid stream
reaches a peak value x periodically, the fluid stream exiting from
the device as shown in FIG. 1 would have a concentration equal to
some percentage of x depending on the ratio of the duration of the
peak concentration value to the average of the delay time of the
substreams. The lower this ratio is, the better the
equalization.
The above theory forms the basis of the present invention, and a
suitable apparatus for the practice of the present invention is
schematically illustrated in FIG. 2. Inlet pipe 8, inlet manifold
9, exit manifold 11 and exit pipe 12 correspond respectively to the
related means in FIG. 1. However, the three pipes (3, 4 and 5) of
FIG. 1 have been replaced by a continuous flat tray 10 in FIG. 2.
The fluid flows into the tray over a weir provided inlet manifold
9, which runs the width of the tray, and similarly, the fluid flows
from the tray into exit manifold 11 over a similar weir in the
latter. In effect, the device shown in FIG. 2 has divided the inlet
stream into an infinite number of substreams, although the inlet
stream is not actually divided into discrete substreams. Depending
upon the width of the tray and the length and depth of the same,
any desired degree of equalization can be obtained, and one skilled
in the art can easily see how the device of the present invention
functions to equalize or dampen fluctuations in concentration of a
substance in the fluid flowing through the device.
In the present invention, equalization essentially equal to a
complete mix basin of the prior art and the same size, is
accomplished with no power input at all. It is simply the geometry
of the device which makes it work.
The basin or tank can be made essentially into any size and shape,
the size depending of course upon the volume of fluid flowing
through the device, the degree of equalization or dampening
desired, etc., and the shape of the device of course being such as
to assure the delay times in the theoretical substreams necessary
to achieve equalization.
FIG. 3 illustrates a typical tank or pond which can be employed to
accomplish the purpose of the present invention. The flow of fluid
through the device is indicated by the arrows in the Figure. The
fluid enters the device along the hypotenuse of the triangle and
flows outwardly therefrom toward one of the sides, where it is
collected by suitable means and withdrawn from the device along
that side. The particular configurations of the inlet and outlet
manifolds is not critical. They may comprise a trough-like
apparatus, wherein the fluid flows over the weir formed by the
lower side of the trough (schematically illustrated in
cross-section in FIG. 4). The edge over which the fluid flows may
either be flat or may be rippled in order to achieve the effect
which is more nearly alike a large number of small separate streams
flowing over the edge of the inlet and exit manifolds. In addition,
a plurality of pipes may be provided along the inlet manifold, each
pipe being capable of discharging an equal volume of water into the
tank.
Generally, any means which distributes the fluid uniformly over the
length of the inlet, and any means which collects it uniformly at
the outlet can be employed in the practice of the present
invention.
A related arrangement is schematically shown in FIG. 5a wherein the
inlet manifold is arranged along the diagonal of the substantially
square or rectangular tank or pond, with the fluid flowing from the
diagonally-disposed inlet manifold (see section A--A in FIG. 5b) to
two adjacent sides of the pond or tank where it is collected by
suitable means (e.g., the troughs shown in sections B--B and C--C
in FIG. 5b).
Another alternative embodiment of the present invention is shown in
FIGS. 6 and 7, FIG. 6 being a plan view and FIG. 7 being a
cross-section along the line A--A of FIG. 6. The inlet may simply
be a pipe which feeds the fluid to the tank at a point off-center
thereof. The outlet shown in FIGS. 6 and 7 (a circular flat, level
weir) surrounds the entire circumference of the tank as shown.
Generally, any shape, tank or pond (dug into the ground) is
suitable for the present invention as long as the geometry of the
device is such as to provide a series of delay times for travel of
the fluid between the inlet and the outlet.
The only criteria for the design of the inlets and outlets is that
the volume of water contained therein must be small relative to the
volume contained in the tank or pond between them, that the flow of
water be discharged (or collected, as the case may be) uniformly
over the length of the inlet or outlet devices and that the number
of discharge or collection points from or to the inlet or outlet
devices to the pond or tank be large. This can generally be
accomplished by providing relatively small inlet and outlet troughs
of the type shown in FIG. 4, where the water flows uniformly over
the lowermost edge thereof and wherein the number of discharge and
collection points can be considered infinite.
The effectiveness of the equalization depends most importantly upon
the volume of fluid which is contained in the pond or tank between
the inlet and outlet, since the larger the volume, the longer the
average retention time of the fluid in the pond or tank, of course,
a longer retention time favoring a greater equalization or
dampening of the fluctuations of the variable concentration which
occurs in the inlet stream.
One skkilled in the art can apply the techniques described above to
any system where it is desirable or necessary to eliminate great
fluctuations in concentrations of a substance in a fluid stream, or
similarly, to eliminate great fluctuations in temperature of a
fluid stream, etc. For example, the present invention finds utility
in the regeneration of zeolite softeners. Such softeners are
normally regenerated with strong salt solutions, and usually on a
batch basis resulting in periods of time where no waste salt
solution is being discharged, and other times when it is being
discharged at a high flow rate. Without equalizing the stream of
waste salt leaving the plant, at times the concentration of salt in
the plant effluent may be so high as to be potentially harmful.
However, if the plant effluent is equalized using the present
invention, the concentration of salt in the effluent would be
essentially the average concentration over a long period of time
which would of course be much lower than the peak values which
would occur without equalization. As a result, the continuous lower
concentration of salt would be much less harmful to the
environment.
The present invention also finds utility in a process for treating
liquid waste from a metallic plating plant. Normally, the metallic
element is removed from the waste stream prior to discharging the
stream to waste. If, however, at several times during the daily
operation of the plant, large concentrations of concentrated
metallic plating solutions are fed to the waste disposal operation,
the entire system must be capable of removing this large
concentration of the metallic element from the waste stream prior
to discharging it. However, for those periods in the daily
operation where a much lower concentration of metallic waste is fed
to the waste treatment operation, the metallic removal system is
greatly over-sized. By installing an equalization device according
to the present invention in the waste treatment operation ahead of
the metallic element removal system, the concentration of the
metallic elements in the waste stream is reduced to an essentially
continuous concentration which is substantially below the peak
concentration normally encountered. The result of course is a
considerable cost savings in the metallic element removing means,
since it need only be designed to handle the equalized
concentration instead of the peak concentration.
Another example, and very pertinent to the present invention, is in
the design of a biological oxidation system to remove dissolved
organic compounds from a flowing stream of water. Normally, a
bio-oxidation system must be designed extremely accurately, since
the system performs poorly if it is overloaded and equally poorly
if it is underloaded. Thus, if there is any significant
concentration variation at all of the organic in the stream which
is the input to the biological oxidation system, it is essential to
equalize the concentration of the organic in the water, and
therefore the present invention finds particular utility in such an
operation.
Although the present invention has been described above with
reference to preferred embodiments, it is to be understood that
variations may be made therefrom without departing from the spirit
and scope of the invention, as is apparent to those skilled in the
art.
* * * * *