U.S. patent application number 14/940231 was filed with the patent office on 2017-05-18 for process for reducing the temperature of an effluent stream flowing out of a sterilization chamber.
The applicant listed for this patent is American Sterilizer Company. Invention is credited to Michael Bacik, Peter J. Buczynski, Shadruz Daraie.
Application Number | 20170138669 14/940231 |
Document ID | / |
Family ID | 56178434 |
Filed Date | 2017-05-18 |
United States Patent
Application |
20170138669 |
Kind Code |
A1 |
Bacik; Michael ; et
al. |
May 18, 2017 |
PROCESS FOR REDUCING THE TEMPERATURE OF AN EFFLUENT STREAM FLOWING
OUT OF A STERILIZATION CHAMBER
Abstract
This invention relates to a process for reducing the temperature
of an effluent stream flowing out of a sterilization chamber. The
process involves the use of a mixing tank and heat exchangers which
provide for cooling the effluent to a temperature required by local
drain or sewer requirements (e.g., below about 60.degree. C.) while
saving on the amount of cooling water needed to cool the
effluent.
Inventors: |
Bacik; Michael; (Fairview,
PA) ; Daraie; Shadruz; (Fairlawn, OH) ;
Buczynski; Peter J.; (Girard, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
American Sterilizer Company |
Mentor |
OH |
US |
|
|
Family ID: |
56178434 |
Appl. No.: |
14/940231 |
Filed: |
November 13, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61L 2/26 20130101; A61L
2/07 20130101; A61L 2202/122 20130101; F28C 3/04 20130101; B01J
3/04 20130101; A61L 2202/13 20130101 |
International
Class: |
F28C 3/04 20060101
F28C003/04 |
Claims
1. A process for reducing the temperature of an effluent stream
from a sterilization chamber, comprising: (A) flowing the effluent
stream from the sterilization chamber through a first heat
exchanger and a vacuum pump into a mixing tank, the effluent stream
flowing from the sterilization chamber being a first stream, the
first stream, which comprises water and/or steam, being cooled in
the first heat exchanger; (B) flowing a second stream, which
comprises water, from the mixing tank through a second heat
exchanger, the second stream being cooled in the second heat
exchanger; (C) flowing the second stream from the second heat
exchanger to and through the first heat exchanger into the mixing
tank, the second stream exchanging heat with the first stream in
the first heat exchanger; (D) flowing a third stream, which
comprises water, through the vacuum pump into the mixing tank; and
(E) flowing a fourth stream, which comprises water, out of the
mixing tank.
2. The process of claim 1 wherein part of the second stream flowing
from the second heat exchanger during step (C) is separated from
the second stream to form the third stream.
3. The process of claim 1 wherein a fifth stream, which comprises
water, is mixed with the second stream flowing from second heat
exchanger to the first heat exchanger.
4. The process of claim 3 wherein part of the fifth stream is
separated from the fifth stream to form the third stream.
5. The process of claim 1 wherein the first stream further
comprises nitrogen, oxygen, or a mixture thereof.
6. The process of claim 1 wherein the mixing tank is equipped with
a temperature detector for measuring the temperature in the mixing
tank.
7. The process of claim 6 wherein the temperature detector is a
resistance temperature detector.
8. The process of claim 1 wherein the second heat exchanger
comprises an air cooled heat exchanger.
9. The process of claim 1 wherein the vacuum pump comprises a
liquid ring vacuum pump.
10. The process of claim 9 wherein the third stream flowing through
the vacuum pump forms a water ring for operating the vacuum
pump.
11. The process of claim 1 wherein a recirculating pump is used to
flow the second stream from the mixing tank to the second heat
exchanger.
12. The process of claim 1 wherein the temperature of the first
stream flowing from the sterilization chamber to the first heat
exchanger is in the range from about 100.degree. C. to about
140.degree. C..
13. The process of claim 1 wherein the first stream flows out of
the first heat exchanger, the temperature of the first stream
flowing out of the first heat exchanger being in the range from
about 75.degree. C. to about 115.degree. C.
14. The process of claim 1 wherein the second stream flows out of
the second heat exchanger, the temperature of the second stream
flowing out of the second heat exchanger being in the range from
about 15.degree. C. to about 60.degree. C.
15. The process of claim 1 wherein the temperature of the second
stream flowing from the first heat exchanger to the mixing tank is
in the range from about 5.degree. C. to about 80.degree. C.
16. The process of claim 3 wherein the temperature of the fifth
stream is in the range from about 10 to about 40.degree. C.
17. The process of claim 3 wherein the ratio of the volumetric flow
rate of the second stream to the volumetric flow rate of the fifth
stream is in the range from about 2 to about 60.
18. The process of claim 1 wherein the fourth stream flowing out of
the mixing tank is at a temperature that is below about 60.degree.
C.
19. The process of claim 1 wherein the fourth stream flowing out of
the mixing tank flows into a drain or a sewer.
Description
TECHNICAL FIELD
[0001] This invention relates to sterilization processes and, more
particularly, to a process for reducing the temperature of an
effluent stream flowing out of a sterilization chamber.
BACKGROUND
[0002] Sterilization processes are used to sterilize a variety of
articles, including medical instruments, and the like. These
processes include steam sterilization processes.
SUMMARY
[0003] Effluent streams (e.g., steam or hot water) flowing out of
steam sterilization chambers are typically disposed of in drains or
local sewer systems. However, according to many local codes, the
temperature of the effluent being disposed of in such drains or
sewer systems usually must be at a temperature below a
pre-determined level, for example, below about 60.degree. C. On the
other hand, the temperature of an effluent flowing out of a typical
steam sterilization chamber is often in the range from about
100.degree. C. to about 140.degree. C. A standard approach to
reducing the temperature of such effluents is to mix the effluent
with water in a mixing tank to cool the effluent to a desired level
prior to its disposal in a drain or sewer system. A problem with
this approach is that it typically requires excessive amounts of
water to cool the effluent adequately to allow it to be disposed of
in a drain or local sewer system. This invention provides a
solution to this problem. An advantage of this invention is that it
allows for disposal of sterilization effluents at temperatures that
are acceptable by local requirements while at the same time
providing for significant reductions in cooling waters required for
such disposal.
[0004] This invention relates to a process for reducing the
temperature of an effluent stream flowing from a sterilization
chamber, comprising: (A) flowing the effluent stream from the
sterilization chamber through a first heat exchanger and a vacuum
pump into a mixing tank, the effluent stream flowing from the
sterilization chamber being a first stream, the first stream, which
comprises water and/or steam, being cooled in the first heat
exchanger; (B) flowing a second stream, which comprises water, from
the mixing tank through a second heat exchanger, the second stream
being cooled in the second heat exchanger; (C) flowing the second
stream from the second heat exchanger to and through the first heat
exchanger into the mixing tank, the second stream exchanging heat
with the first stream in the first heat exchanger; (D) flowing a
third stream, which comprises water, through the vacuum pump into
the mixing tank; and (E) flowing a fourth stream, which comprises
water, out of the mixing tank.
[0005] In an embodiment, part of the second stream flowing from the
second heat exchanger during step (C) is separated from the second
stream to form the third stream.
[0006] In an embodiment, a fifth stream, which comprises water, is
mixed with the second stream flowing from second heat exchanger to
the first heat exchanger.
[0007] In an embodiment, part of the fifth stream is separated from
the fifth stream to form the third stream.
[0008] In an embodiment, the first stream further comprises
nitrogen, oxygen, or a mixture thereof.
[0009] In an embodiment, the mixing tank is equipped with a
temperature detector for measuring the temperature in the mixing
tank. The temperature detector may be a resistance temperature
detector (RTD).
[0010] In an embodiment, the second heat exchanger comprises an air
cooled heat exchanger.
[0011] In an embodiment, the vacuum pump comprises a liquid ring
vacuum pump. The third stream flowing through the vacuum pump may
be used to form a water ring for operating the vacuum pump.
[0012] In an embodiment, a recirculating pump is used to flow the
second stream from the mixing tank through the second heat
exchanger.
[0013] In an embodiment, the temperature of the first stream
flowing from the sterilization chamber to the first heat exchanger
is in the range from about 100.degree. C. to about 140.degree. C.,
or from about 100.degree. C. to about 130.degree. C., or from about
100.degree. C. to about 120.degree. C.
[0014] In an embodiment, the first stream flows out of the first
heat exchanger, the temperature of the first stream flowing out of
the first heat exchanger being in the range from about 75.degree.
C. to about 115.degree. C., or from about 75.degree. C. to about
105.degree. C.
[0015] In an embodiment, the temperature of the second stream
flowing out of the second heat exchanger is in the range from about
15.degree. C. to about 60.degree. C., or from about 15.degree. C.
to about 50.degree. C., or from about 15.degree. C. to about
40.degree. C.
[0016] In an embodiment, the temperature of the second stream
flowing from the first heat exchanger to the mixing tank is in the
range from about 5 to about 80.degree. C., or from about 40 to
about 75.degree. C.
[0017] In an embodiment, the temperature of the fifth stream is in
the range from about 10.degree. C. to about 40.degree. C., or about
15.degree. C. to about 30.degree. C., or about 18.degree. C. to
about 24.degree. C.
[0018] In an embodiment, the ratio of the volumetric flow rate of
the second stream to the volumetric flow rate of the fifth stream
is in the range from about 2 to about 60, or about 4 to about
20.
[0019] In an embodiment, the temperature of the fourth stream
flowing out of the mixing tank is below about 60.degree. C., or
below about 55.degree. C., or below about 50.degree. C. The fourth
stream flowing out of the mixing tank may flow into a drain or
sewer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the annexed drawings, like references indicate like parts
and features.
[0021] FIG. 1 is a flow sheet showing a process for reducing the
temperature of an effluent stream flowing from a sterilization
chamber pursuant to the invention.
[0022] FIG. 1A is a flow sheet showing an alternate embodiment of
the process illustrated in FIG. 1.
[0023] FIG. 2 is a schematic illustration of an apparatus used in
the process illustrated in FIG. 1.
DETAILED DESCRIPTION
[0024] All ranges and ratio limits disclosed in the specification
and claims may be combined in any manner. It is to be understood
that unless specifically stated otherwise, references to "a," "an,"
and/or "the" may include one or more than one, and that reference
to an item in the singular may also include the item in the
plural.
[0025] The phrase "and/or" should be understood to mean "either or
both" of the elements so conjoined, i.e., elements that are
conjunctively present in some cases and disjunctively present in
other cases. Other elements may optionally be present other than
the elements specifically identified by the "and/or" clause,
whether related or unrelated to those elements specifically
identified unless clearly indicated to the contrary. Thus, as a
non-limiting example, a reference to "X and/or Y," when used in
conjunction with open-ended language such as "comprising" can
refer, in one embodiment, to X without Y (optionally including
elements other than Y); in another embodiment, to Y without X
(optionally including elements other than X); in yet another
embodiment, to both X and Y (optionally including other elements);
etc.
[0026] The word "or" should be understood to have the same meaning
as "and/or" as defined above. For example, when separating items in
a list, "or" or "and/or" shall be interpreted as being inclusive,
i.e., the inclusion of at least one, but also including more than
one, of a number or list of elements, and, optionally, additional
unlisted items. Only terms clearly indicated to the contrary, such
as "only one of" or "exactly one of," or may refer to the inclusion
of exactly one element of a number or list of elements. In general,
the term "or" as used herein shall only be interpreted as
indicating exclusive alternatives (i.e. "one or the other but not
both") when preceded by terms of exclusivity, such as "either,"
"one of," "only one of," or "exactly one of."
[0027] The phrase "at least one," in reference to a list of one or
more elements, should be understood to mean at least one element
selected from any one or more of the elements in the list of
elements, but not necessarily including at least one of each and
every element specifically listed within the list of elements and
not excluding any combinations of elements in the list of elements.
This definition also allows that elements may optionally be present
other than the elements specifically identified within the list of
elements to which the phrase "at least one" refers, whether related
or unrelated to those elements specifically identified. Thus, as a
non-limiting example, "at least one of X and Y" (or, equivalently,
"at least one of X or Y," or, equivalently "at least one of X
and/or Y") can refer, in one embodiment, to at least one,
optionally including more than one, X, with no Y present (and
optionally including elements other than Y); in another embodiment,
to at least one, optionally including more than one, Y, with no X
present (and optionally including elements other than X); in yet
another embodiment, to at least one, optionally including more than
one, X, and at least one, optionally including more than one, Y
(and optionally including other elements); etc.
[0028] The transitional words or phrases, such as "comprising,"
"including," "carrying," "having," "containing," "involving,"
"holding," and the like, are to be understood to be open-ended,
i.e., to mean including but not limited to.
[0029] The term "sterilization" refers to rendering a substance
incapable of reproduction, metabolism and/or growth. The term
"sterilization" includes microbial deactivation. While
sterilization is often taken to refer to a total absence of living
organisms, the term may be used herein to refer to a substance free
from living organisms to a degree agreed to be acceptable. Unless
otherwise indicated, the term "sterilization" may be used herein to
also refer to processes less rigorous than sterilization, for
example, disinfection, sanitization, decontamination, cleaning, and
the like. Variations of the term "sterilization," such as
sterilant, sterilizing, etc., may also be used herein to refer to
and encompass related variants associated with sterilization
processes as well as processes less rigorous than sterilization
(e.g., disinfectant, disinfecting, etc.). The sterilization process
may comprise a steam sterilization process.
[0030] The term "sterilization chamber" refers to a chamber wherein
a sterilization process is conducted. The sterilization chamber may
comprise a steam sterilization chamber.
[0031] The term "effluent" refers to any fluid (liquid, vapor, or
mixture thereof) flowing out of a sterilization chamber that is to
be discarded, for example, disposed of in a drain or sewer system.
The effluent may comprise steam, hot water (or steam condensate),
or a mixture thereof.
[0032] Referring to FIGS. 1, 1A and 2, this invention relates to a
process for reducing the temperature of an effluent stream flowing
from sterilization chamber 10 using effluent cooling system 20.
[0033] The sterilization chamber 10 may be of any desired size and
design. The sterilization chamber 10 may be a steam sterilization
chamber. The internal temperature of the sterilization chamber
during the operation of a sterilization cycle may be in the range
from about 100 to about 140.degree. C., or from about 100 to about
125.degree. C., or from about 130 to about 140.degree. C. The
internal pressure (absolute pressure) within the sterilization
chamber 10 during a sterilization cycle may be in the range from
about 1 to about 3 atmospheres, or from about 1 to about 2
atmospheres. The internal volume of the sterilization chamber 10
may be of any useful dimension, for example, in the range from
about 100 to about 1000 liters, or from about 200 to about 1000
liters.
[0034] The effluent flowing out of the sterilization chamber 10
through line 12 may comprise steam, water (e.g., steam condensate),
or a mixture thereof. This effluent stream may be referred to as
the first stream. The first stream may also contain other fluids,
for example, nitrogen, oxygen, or a mixture thereof, and the like.
The flow rate of the first stream flowing out of the sterilization
chamber 10 through line 12 may be in the range from about 0.05 to
about 100 liters per minute (lpm), or from about 0.1 to about 100
lpm, or from about 0.1 to about 80 lpm, or from about 0.1 to about
60 lpm, or from about 0.1 to about 40 lpm. The temperature of the
first stream flowing out of the sterilization chamber 10 in line 12
may in the range from about 100.degree. C. to about 140.degree. C.,
or from about 100.degree. C. to about 125.degree. C., or from about
130.degree. C. to about 140.degree. C.
[0035] The effluent cooling system 20 includes first heat exchanger
30, second heat exchanger 40, vacuum pump 50, recirculation pump
60, and mixing tank 70. The first stream flows from the
sterilization chamber 10 through valve 11 and line 12 to and
through first heat exchanger 30, and from the heat exchanger 30
through line 32 to vacuum pump 50, and from vacuum pump 50 through
line 52 to mixing tank 70.
[0036] The second stream, which comprises water, flows from mixing
tank 70 through line 72 to recirculation pump 60, and then from
recirculation pump 60 to and through second heat exchanger 40. Heat
exchanger 40 may be an air cooled heat exchanger using fan 41. The
second stream is cooled in the second heat exchanger 40 and flows
out of the second heat exchanger 40 through line 42. The second
stream flowing out of the second heat exchanger 40 through line 42
may have a temperature in the range from about 15.degree. C. to
about 60.degree. C., or from about 15.degree. C. to about
50.degree. C., or from about 15.degree. C. to about 40.degree. C.,
or from about 45.degree. C. to about 60.degree. C. The flow rate of
the second stream in line 42 may be in the range from about 15 to
about 100 lpm, or from about 15 to about 95 lpm, or from about 15
to about 60 lpm.
[0037] The second stream flows from line 42 to and through line 44
to line 85. In an embodiment, the second stream may flow through
line 85 to and through first heat exchanger 30, and then through
line 33 to mixing tank 70.
[0038] In an embodiment (FIG. 1), part of the second stream may be
diverted to line 46 where it flows as the third stream through line
46 and valve 47 to vacuum pump 50, and then from vacuum pump 50
through line 52 to mixing tank 70.
[0039] In an embodiment, fifth stream 80 may flow through line 82
and valve 83 into line 85 where it may be mixed with the second
stream flowing from line 44. The fifth stream may comprise local
water or utility water. The fifth stream may have a temperature in
the range from about 10 to about 40.degree. C., or about 15 to
about 30.degree. C., or about 18 to about 24.degree. C. When the
second and fifth streams are mixed, the ratio of the volumetric
flow rate of the second stream to that of the fifth stream may be
in the range from about 2 to about 60, or from about 4 to about
20.
[0040] The second stream, or the second stream mixed with the fifth
stream, may flow through line 85 to and through first heat
exchanger 30, and then through line 33 to mixing tank 70. The
second stream, or the second stream mixed with the fifth stream,
flowing through first heat exchanger 30 exchanges heat with the
first stream flowing through the first heat exchanger 30. The first
stream may be cooled in the first heat exchanger 30. The second
stream, or the second stream mixed with the fifth stream, flowing
from first heat exchanger 30 through line 33 to mixing tank 70 may
have a temperature in the range from about 75 to about 115.degree.
C., or from about 75 to about 100.degree. C., or from about 105 to
about 115.degree. C. The flow rate of the second stream, or the
second stream mixed with the fifth stream, through line 33 may be
in the range from about 0.05 to about 100 lpm, or from about 0.1 to
about 100 lpm, or from about 0.1 to about 80 lpm, or from about 0.1
to about 60 lpm, or from about 0.1 to about 40 lpm.
[0041] Vacuum pump 50 may be used to draw the first stream from the
sterilization chamber 10 through valve 11 and line 12. The first
stream may flow to and through the first heat exchanger 30, and
then from the heat exchanger 30 through line 32 to vacuum pump 50,
and then from the vacuum pump 50 through line 52 to mixing tank 70.
The vacuum pump 50 may be a liquid ring vacuum pump. In an
embodiment (FIG. 1), the third stream may flow from the second heat
exchanger 40 through lines 42 and 46 and valve 47 to the vacuum
pump 50, and then from the vacuum pump 50 through line 52 to mixing
tank 70. In an alternate embodiment (FIG. 1A), part of the fifth
stream may be diverted from line 82 to line 84, and flow as the
third stream from line 84 through valve 47 to vacuum pump 50, and
then from vacuum pump 50 through line 52 to mixing tank 70. The
third stream may be used to form a water ring for operating the
vacuum pump 50. The flow rate of the third stream through the
vacuum pump 50 may be in the range up to about 12 lpm, or from
about 1 to about 12 lpm, or from about 1 to about 6 lpm. Vacuum
pump 50 may be drained through line 48 and valve 49 when it is not
running. Valve 49 may be used to prevent free flow to drain 16.
[0042] The mixing tank 70 may have any desired size. For example,
the mixing tank 70 may have an internal capacity in the range from
about 1 to about 40 liters, or from about 3 to about 38 liters, or
from about 3 to about 8 liters, or from about 8 to about 38 liters.
The mixing tank 70 may be equipped with a temperature detector 74
for measuring the temperature of the water 71 in the mixing tank
70. The temperature detector 74 may be a resistance temperature
detector (RTD). The mixing tank 70 may also be equipped with a
liquid level control device 76, which may be of any conventional
design. The temperature of the water 71 in mixing tank 70 may be
monitored, and if the temperature goes above a pre-determined level
(e.g., above about 60.degree. C.), water from the second stream, or
the second stream mixed with the fifth stream, from line 33 may be
added to the water 71 to bring the temperature of the water 71 down
to the required level.
[0043] The fourth stream, which comprises water, flows out of the
mixing tank 70 through line 75 to drain 16. Line 75 may include a
drain funnel 77. The water flowing through line 75 may be referred
to as the fourth stream. The temperature of the fourth stream
flowing from the mixing tank 70 to drain 16 may be below about
60.degree. C., or below about 55.degree. C., or below about
50.degree. C. The flow rate of the fourth stream may be in the
range from 0.05 to about 100 lpm, or from about 0.05 to about 80
lpm, or from about 0.05 to about 60 lpm. The flow rate may be from
0 to about 95 lpm, or from 0 to about 57 lpm.
[0044] The mixing tank 70 may be have a relatively large volume,
for example, in the range from about 1 to about 40 liters, with a
relatively large surface area that is exposed to the ambient air,
for example, from about 500 to about 40,000 cm.sup.2, or from about
800 to about 32,000 cm.sup.2. By using such a large mixing tank
with such a large surface area, the water 71 in the mixing tank 70
and the relatively hot water flowing into the mixing tank 70 can be
mixed and the temperature of the water 71 in the mixing tank 70 may
be allowed to equilibrate relatively quickly. The water 71 in the
mixing tank may tend to lose heat through the relatively large
surface area of the tank. By using the cooling system 20 in
combination with the relatively large mixing tank 70, considerable
reductions in water consumption, for example, at least about 20%,
or at least about 40%, or at least about 60% or more, per
sterilization cycle, may be achieved.
[0045] While the invention has been explained in relation to
various embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in the
art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein includes any such
modifications that may fall within the scope of the appended
claims.
* * * * *