U.S. patent application number 16/182074 was filed with the patent office on 2019-11-14 for producing high-purity chlorine dioxide gas.
This patent application is currently assigned to GuangXi University. The applicant listed for this patent is GuangXi University. Invention is credited to Chen LIANG, Xinliang LIU, Shuangxi NIE, Chengrong QIN, Xueping SONG, Shuangfei WANG, Zhiwei WANG, HongXiang ZHU.
Application Number | 20190345033 16/182074 |
Document ID | / |
Family ID | 63204980 |
Filed Date | 2019-11-14 |
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United States Patent
Application |
20190345033 |
Kind Code |
A1 |
WANG; Shuangfei ; et
al. |
November 14, 2019 |
PRODUCING HIGH-PURITY CHLORINE DIOXIDE GAS
Abstract
A high-purity chlorine dioxide gas may use hydrogen peroxide as
a reducing agent and may use horizontal generator, evaporation
crystallizer, dryer and other devices to produce chlorine dioxide
gas (product) and sodium sulfate (by-product). Compared to the
conventional chlorine dioxide preparation system, the chlorine
dioxide reaction and the sodium sulfate crystallization are
performed in two processes. These processes are relatively separate
and independent, and continuously produce chlorine dioxide gas with
high purity and low moisture content while the by-product salt cake
is evaporated, crystallized, filtered and dried, thereby producing
sodium sulfate, without generating solid and liquid waste.
Inventors: |
WANG; Shuangfei; (Nanning,
CN) ; QIN; Chengrong; (Nanning, CN) ; NIE;
Shuangxi; (Nanning, CN) ; SONG; Xueping;
(Nanning, CN) ; LIANG; Chen; (Nanning, CN)
; LIU; Xinliang; (Nanning, CN) ; WANG; Zhiwei;
(Nanning, CN) ; ZHU; HongXiang; (Nanning,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GuangXi University |
Nanning |
|
CN |
|
|
Assignee: |
GuangXi University
|
Family ID: |
63204980 |
Appl. No.: |
16/182074 |
Filed: |
November 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16011684 |
Jun 19, 2018 |
10266406 |
|
|
16182074 |
|
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 9/0022 20130101;
B01J 2219/182 20130101; B01D 2257/2025 20130101; B01J 7/02
20130101; C01B 11/026 20130101; B01D 2256/26 20130101; B01J 19/24
20130101; B01D 9/0059 20130101 |
International
Class: |
C01B 11/02 20060101
C01B011/02; B01D 9/00 20060101 B01D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2018 |
CN |
201804829036 |
Claims
1. The method for producing high-purity chlorine dioxide gas,
comprising: using hydrogen peroxide as a reducing agent; and using
a horizontal generator, an evaporation crystallizer, a dryer and
other devices to produce a product comprising chlorine dioxide gas
and a by-product comprising sodium sulfate, wherein chlorine
dioxide reaction is produced by using the horizontal generator to
produce chlorine dioxide, adding air into the horizontal generator,
and stirring a reaction liquid and diluting the chlorine dioxide
gas continuously to produce the chlorine dioxide gas with high
purity and low moisture content, and sodium sulfate crystallization
is produced by evaporating, crystallizing, filtering, and drying a
salt cake in the evaporation crystallizer and dryer to produce
sodium sulfate powder.
2. A method for producing high-purity chlorine dioxide gas in that
hydrogen peroxide, sulfuric acid and sodium chlorate are used as
raw materials to produce high-purity and low-moisture chlorine
dioxide gas while salt cake is dried to produce sodium sulfate, the
method comprising: entering sulfuric acid in a horizontal generator
via a pipe; delivering a reducing agent through another pipe such
that the reducing agent enters the horizontal generator after being
mixed with sodium chlorate in a tertiary pipe; generating a
chlorine dioxide gas when a REDOX reaction occurs; entering heat
source into the horizontal generator by way of a pipe to step heat
the reaction liquid, to force the temperature of the reaction
liquid to increase from 20-30.degree. C. to 80-85.degree.;
compressing the air by an air compressor such that the compressed
air enters into the horizontal generator and stirring the reaction
liquid to make the reaction uniform while releasing and diluting
the chlorine dioxide gas; blowing air, by a blower, into the
horizontal generator for further diluting the chlorine dioxide gas
concentration to 4-9% (V/V); sending the diluted chlorine dioxide
gas to use areas by an induced draft fan; while the raw material
enters the horizontal generator from one end, discharging the
reacted reaction liquid from another end of the horizontal
generator and into the mother liquid discharge tank for storage;
sending the discharged reaction liquid into the mother liquid lower
circulating pipe by a crystallizer feed pump, and circulation,
heating, evaporation and concentration between evaporation
crystallizer and heater under a pumping action of a circulating
pump, wherein the temperature in the evaporation crystallizer is
controlled at 70-73.degree. C., the vacuum pressure is controlled
at -79 to -81 KPa(g); concentrating and crystalizing sodium sulfate
in the mother liquid and depositing the sodium sulfate at the
bottom of the evaporation crystallizer, wherein the sodium sulfate
is sent to a filtration device through a feed pump for filtration,
washing and decrease water percent; introducing salt cake solid
into a dryer to produce sodium sulfate with dryness up to 99.5%;
returning a filtrate liquid to the mother liquid circulating pipe
via the filtrate pipe for recycling, wherein neither solid nor
liquid wastes are produced throughout the production process;
sending the clarified mother liquid from the upper part of the
evaporation crystallizer to the mother liquid tank by a mother
liquid extraction pump for buffering; and sending clarified mother
liquid to the horizontal generator by the mother liquid return
pump.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of, and claim priority to,
U.S. patent application Ser. No. 16/011,684, filed on Jun. 19,
2018, which claims the benefit of, and priority to, Chinese Patent
Application No. 2018104829036, filed on May 8, 2018. The subject
matter thereof is hereby incorporated herein by reference in its
entirety.
FIELD
[0002] The present invention generally relates to chlorine dioxide
preparation, and more particularly, to a process, system, and
apparatus for producing high-purity chlorine dioxide gas.
BACKGROUND
[0003] Chlorine dioxide (ClO2) is a yellow orange gas at normal
temperature and pressure and has an irritating and spicy taste
similar to a mixture of chlorine and ozone. The boiling point is
11.degree. C., the freezing point is -59.degree. C., and the
gaseous density is 3.09 g/m.sup.3 at 11.degree. C. Gaseous
ClO.sub.2 is unstable. Exposure to light or organic matter at high
concentration will decompose violently and production of oxygen and
chlorine. Normally it must be produced at the mill near its point
of application. It is more stable when diluted to lower than 12%
volume content with air or steam at atmospheric temperature or in
the state of a low-temperature water solution. ClO.sub.2 is a
strong oxidizer and can be used as a bleaching agent for pulp and
textiles, and as water treatment agent, new air purifying
freshener, and a disinfection, sterilizing, deodorizing agent for
food, epidemic prevention, hygiene, etc.
[0004] At present, the main methods of producing chlorine dioxide
include methanol method and integrated method. Methanol method uses
methanol, sulfuric acid, and sodium chlorate as raw materials, and
the vertical generator is used to produce chlorine dioxide. The
product of chlorine dioxide has a large moisture content up to 80%
(w/w) or more, and contains a small amount of chlorine; The
integrated method uses hydrochloric acid and sodium chlorate as raw
materials and both vertical generator and horizontal generator can
be used, but chlorine dioxide gas contains a lot of chlorine, and
the molar ratio of chlorine dioxide to chlorine is 2:1. For the use
areas with high purity requirements (such as sodium chlorite
preparation, food and medicine area, etc.), the purity of chlorine
dioxide produced by the above two preparation methods cannot meet
the use requirements.
[0005] In addition, chlorine dioxide product produced by common
industrial chlorine dioxide preparation device are pumped to the
final use areas in the form of low-temperature chlorine dioxide
solution, not supplied in the form of gas.
[0006] Accordingly, an improved process and apparatus for producing
high-purity chlorine dioxide gas may be beneficial.
SUMMARY
[0007] Certain embodiments of the present invention may provide
solutions to the problems and needs in the art that have not yet
been fully identified, appreciated, or solved by conventional
chlorine dioxide preparation technologies. For example, some
embodiments pertain to a process and apparatus for producing
high-purity chlorine dioxide gas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In order that the advantages of certain embodiments of the
invention will be readily understood, a more particular description
of the invention briefly described above will be rendered by
reference to specific embodiments that are illustrated in the
appended drawings. While it should be understood that these
drawings depict only typical embodiments of the invention and are
not therefore to be considered to be limiting of its scope, the
invention will be described and explained with additional
specificity and detail through the use of the accompanying
drawings, in which:
[0009] FIG. 1 is a schematic diagram illustrating a high-purity
chlorine dioxide gas production device, according to an embodiment
of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0010] FIG. 1 is a schematic diagram illustrating a high-purity
chlorine dioxide gas production device 100, according to an
embodiment of the present invention. The devices for producing
high-purity chlorine dioxide gas including a horizontal generator
(4), blower (7), induced draft fan (8), mother liquid discharge
tank (9), crystallizer feed pump (10), circulating pump (11),
heater (12), evaporation crystallizer (13), filtration unit feed
pump (14), filtration unit (15), dryer (16), mother liquid
extraction pump (17), mother liquid tank (18), mother liquid return
pump (19), air compressor (30). The sulfuric acid pipe (1) is
connected with the horizontal generator (4); the hydrogen peroxide
pipe (2) joins the sodium chlorate pipe (3) and are connected to
the horizontal generator (4); the heat source pipe (5) is connected
to the inlet of the horizontal generator (4); the compressed air
pipe (6) is connected to the air compressor (30) and the horizontal
generator (4); the horizontal generator (4) is connected to the
mother liquid discharge tank (9) through a reaction liquid (mother
liquid) discharge pipe (25); the mother liquid discharge tank (9)
is connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and mother liquid upper
circulating pipe (24) are connected with the evaporation
crystallizer (13), heater (12) and the circulating pump (11); the
mother liquid tank (18) is connected to the evaporation
crystallizer (13) and the horizontal generator (4) respectively
through the inlet/outlet pipe of the mother liquid extraction pump
(27) and the inlet/outlet pipe of the mother liquid return pump
(20); the heat source pipe (21) is connected to the inlet pipe of
the heater (12); the filtration unit (15) is connected to the
mother liquid lower circulating pipe (23) through the inlet/outlet
pipe of the feed pump (28) and the filtrate pipe (22) to form a
circulation loop; the filtration unit (15) is connected to the
dryer (16) via the salt cake discharge pipe (29).
[0011] In some embodiments, to make the chlorine dioxide
preparation system run smoothly and continuously, a mother liquid
discharge tank (9) with buffer effect and a mother liquid tank (18)
are equipped between the horizontal generator (4) and the
evaporation crystallizer (13). The chlorine dioxide reaction device
and the evaporation crystallization device are relatively separated
and independent.
[0012] In some embodiments, to make the reaction liquid of the
horizontal generator (4) enter to the evaporation crystallizer
(13), the reaction liquid discharge pipe (25) and inlet/out pipe
(26) of the crystallizer feed pump are equipped before and after
the mother liquid discharge tank (9). to respectively connect with
the horizontal generator (4) and mother liquid lower circulating
pipe (23). To make the supernatant of the evaporation crystallizer
(13) return to the horizontal generator (4), the mother liquid
return pump (19), extraction pump (17) and corresponding pipeline
are equipped before and after the mother liquid tank (18) and are
respectively connected to the evaporation crystallizer (13) and the
horizontal generator (4).
[0013] In certain embodiments, to facilitate the circulation,
evaporation and concentration of the mother liquid, the evaporation
crystallizer (13), heater (12) and circulation pump (11) are
connected in series by the mother liquid lower circulating pipe
(23) and upper circulating pipe (24) to form a circulation
loop.
[0014] In an embodiment, to make full use of the salt cake and
filtrate and avoid waste generated, the filtration unit (15) is
provided with filtrate pipe (22) and salt cake discharge pipe (29)
to respectively connect with the mother liquid lower circulating
pipe (23) and dryer (16) to form a filtrate liquid return channel
and salt cake treatment channel.
[0015] The invention provides a method for producing high-purity
chlorine dioxide gas by using hydrogen peroxide, sulfuric acid and
sodium chlorate as raw materials to produce chlorine dioxide and
drying the salt cake to produce salt cake powder. The specific
steps are as follows:
[0016] Step 1, sulfuric acid enters the horizontal generator (4)
through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters the horizontal generator
(4) after being mixed with the sodium chlorate in the pipe (3),
chlorine dioxide gas is generated after the redox reaction.
[0017] Step 2, while the raw material enters the horizontal
generator (4) from one end, the reaction liquid after reacted is
discharged from the other end into the mother liquid discharge tank
(9) for storage, and then sent to the mother liquid into the lower
circulating pipe (23) by the crystallizer feed pump (10).
circulation, heating, evaporation and concentration between the
evaporation crystallizer (13) and the heater (12) under the pumping
action of the circulating pump (11); the salt cake in the mother
liquid is concentrated and crystallized and is deposited at the
bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration unit (15) through
the feed pump (14) for filtration, washing and concentration.
Concentrated solid salt cake enters the dryer (16) to produce
sodium sulfate powder with a dryness up to 99.5% (which can be sold
as a byproduct); the filtrate liquid is returned to the mother
liquid circulating pipe (23) via the filtrate liquid pipe (22).
[0018] Step 3, the clarified mother liquid in the upper of the
evaporation crystallizer (13) is sent to the mother liquid tank
(18) by the mother liquid extraction pump (17) for buffering, and
then sent to the horizontal generator (4) by the mother liquid
return pump (19).
[0019] In some embodiments, the heat source adds to the horizontal
generator (4) through pipe (5) to heat the reaction solution
indirectly, under the small negative pressure condition, the
temperature of the reaction liquid is step increased from
20-30.degree. C. to 80-85.degree. C.; the air is compressed by the
air compressor (30) and then enters the horizontal generator (4)
and stirs the reaction liquid to make the reaction uniform while
releasing and diluting the chlorine dioxide gas; in addition, the
blower (7) blows the air into the horizontal generator (4) for
further diluting the chlorine dioxide gas concentration to 4-9%
(V/V); the diluted chlorine dioxide gas is sent out to the end use
areas by the induced draft fan (8). The above-mentioned process can
avoid the violent reaction during the preparation process and high
concentration of chlorine dioxide, thus to avoid ClO.sub.2
decomposition, as well as avoid the salt cake crystallization in
the horizontal generator (4) due to the high reaction temperature
and excess water evaporation. The achieved chlorine dioxide gas has
a moisture content of less than 8% (w/w) and is substantially free
of chlorine.
[0020] In some embodiments, to increase the evaporation efficiency
and save heat source, the temperature in the evaporation
crystallizer is controlled at 70-73.degree. C. And the vacuum is
controlled at -79 to -81 KPa (g).
[0021] The invention provides a method and devices for producing
high-purity chlorine dioxide gas, which have the following
advantages and effects:
[0022] The invention describes a device for producing high-purity
chlorine dioxide gas, a mother liquid discharge tank (9) and a
mother liquid tank (18) are equipped between the horizontal
generator (4) and the evaporation crystallizer (13), make the
chlorine dioxide reaction device and the evaporation
crystallization device relatively separated and independent.
Meanwhile, the mother liquid discharge tank (9) and the mother
liquid tank (18) play a role in buffering, so that the chlorine
dioxide preparation system can be continuously and smoothly
running.
[0023] A method described in the invention, by which the chlorine
dioxide gas is produced with high purity, is using the hydrogen
peroxide, sulfuric acid and sodium chlorate as raw materials and
adopting a horizontal generator, the reaction liquid is heated step
by step from 25.degree. C. to 85.degree. C. under a small negative
pressure condition, which can effectively avoid salt cake
crystallization in the generator due to excessive evaporation of
the reaction liquid and blocking the generator, as well as to avoid
chlorine dioxide decomposition due to the violent reaction, and the
prepared chlorine dioxide gas has a moisture content less than 8%
(w/w) and essentially free of chlorine; the blower (7) blows the
air into the horizontal generator (4) to dilute the chlorine
dioxide gas concentration to 4-9% (V/V) to ensure the chlorine
dioxide is stable and not decomposed easily. The by-product salt
cake can be concentrated and crystallized by controlling the
temperature in the evaporation crystallizer at 70-73.degree. C. and
the vacuum degree at -79 to -81 KPa (g) to produce sodium sulfate
powder after being filtered and dried. The filtrate liquid returns
to the mother liquid lower circulating pipe (23) through pipe (22),
no solid and liquid wastes produced.
[0024] This invention will be described in detail below with
reference to the accompanying drawings and embodiments. The
described embodiments are merely some but not all of the
embodiments of this invention. All the other embodiments obtained
by the technical person in this field based on the embodiments of
this invention without creative efforts shall fall within the
protection scope of the present invention.
EXAMPLE 1
[0025] As shown in FIG. 1, devices for producing high-purity
chlorine dioxide gas include a horizontal generator (4), blower
(7), induced draft fan (8), mother liquid discharge tank (9),
crystallizer feed pump (10), circulating pump (11), heater (12),
evaporation crystallizer (13), filtration unit feed pump (14),
filtration unit (15), dryer (16), mother liquid extraction pump
(17), mother liquid tank (18), mother liquid return pump (19), air
compressor (30). The sulfuric acid pipe (1) is connected with the
horizontal generator (4); the hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and are connected to the horizontal
generator (4); the heat source pipe (5) is connected to the inlet
of the horizontal generator (4); the compressed air pipe (6) is
connected to the air compressor (30) and the horizontal generator
(4); the horizontal generator (4) is connected to the mother liquid
discharge tank (9) through a reaction liquid (mother liquid)
discharge pipe (25); the mother liquid discharge tank (9) is
connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and upper circulating
pipe (24) are connected with the evaporation crystallizer (13),
heater (12) and the circulating pump (11); the mother liquid tank
(18) is connected to the evaporation crystallizer (13) and the
horizontal generator (4) through the inlet/outlet pipe of the
mother liquid extraction pump (27) and the inlet/outlet pipe of the
mother liquid return pump (20); the heat source pipe (21) is
connected to the inlet pipe of the heater (12); the filtration unit
(15) is connected to the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe of the feed pump (28) and the
filtrate pipe (22) to form a circulation loop; the filtration unit
(15) is connected to the dryer (16) via the salt cake discharge
pipe (29).
[0026] Step 1, sulfuric acid enters into the horizontal generator
(4) through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters into the horizontal
generator (4) after being mixed with the sodium chlorate in pipe
(3), chlorine dioxide gas is generated after the redox reaction.
The heat source enters the horizontal generator (4) through pipe
(5) to gradually heat the reaction liquid, so that the temperature
of the reaction liquid is increased from 20.degree. C. to
80.degree. C. The air is compressed by the air compressor (30) and
then enters into the horizontal generator (4) and stirs the
reaction liquid to make the reaction uniform while releasing and
diluting the chlorine dioxide gas; in addition, the blower (7)
blows the air into the horizontal generator (4) for further
diluting the chlorine dioxide gas concentration to 4% (V/V); the
diluted chlorine dioxide gas is sent out to the end use areas by
the induced draft fan (8). The product has a moisture content of
7.8% (w/w) and is essentially free of chlorine.
[0027] Step 2, while the raw material enters into the horizontal
generator (4) from one end, the reacted reaction liquid is
discharged from the other end of the horizontal generator to the
mother liquid discharge tank (9) for storage, and then sent to the
mother liquid lower circulating pipe (23) by the crystallizer feed
pump (10), and circulation, heating, evaporation and concentration
between the evaporation crystallizer (13) and the heater (12) under
the pumping action of the circulating pump (11); the temperature in
the evaporation crystallizer is controlled at 73.degree. C., the
vacuum degree is controlled at -79 KPa(g). The salt cake in the
mother liquid is concentrated and crystallized and is deposited at
the bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration device (15)
through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate powder with dryness up to
99.6% (which can be sold as a byproduct); the filtrate liquid is
returned to the mother liquid circulating pipe (23) via the
filtrate pipe (22) for recycling. No solid and liquid wastes
produced throughout the production process.
[0028] Step 3, the clarified mother liquid in the upper of the
evaporation crystallizer (13) is sent to the mother liquid tank
(18) by the mother liquid extraction pump (17) for buffering, and
then sent to the horizontal generator (4) by the mother liquid
return pump (19).
EXAMPLE 2
[0029] As shown in FIG. 1, devices for producing high-purity
chlorine dioxide gas includes a horizontal generator (4), blower
(7), induced draft fan (8), mother liquid discharge tank (9),
crystallizer feed pump (10), circulating pump (11), heater (12),
evaporation crystallizer (13), filtration unit feed pump (14),
filtration unit (15), dryer (16), mother liquid extraction pump
(17), mother liquid tank (18), mother liquid return pump (19), air
compressor (30). The sulfuric acid pipe (1) is connected with the
horizontal generator (4); the hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and are connected to the horizontal
generator (4); the heat source pipe (5) is connected to the inlet
of the horizontal generator (4); the compressed air pipe (6) is
connected to the air compressor (30) and the horizontal generator
(4); the horizontal generator (4) is connected to the mother liquid
discharge tank (9) through a reaction liquid (mother liquid)
discharge pipe (25); the mother liquid discharge tank (9) is
connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and upper circulating
pipe (24) are connected with the evaporation crystallizer (13),
heater (12) and the circulating pump (11); the mother liquid tank
(18) is connected to the evaporation crystallizer (13) and the
horizontal generator (4) through the inlet/outlet pipe of the
mother liquid extraction pump (27) and the inlet/outlet pipe of the
mother liquid return pump (20); the heat source pipe (21) is
connected to the inlet pipe of the heater (12); the filtration unit
(15) is connected to the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe of the feed pump (28) and the
filtrate pipe (22) to form a circulation loop; the filtration unit
(15) is connected to the dryer (16) via the salt cake discharge
pipe (29).
[0030] The method for preparing 8 t/d chlorine dioxide gas using
the above mentioned device is as follows:
[0031] Step 1, sulfuric acid enters the horizontal generator (4)
through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters the horizontal generator
(4) after being mixed with the sodium chlorate in pipe (3),
chlorine dioxide gas is generated after the redox reaction. The
heat source enters into the horizontal generator (4) through pipe
(5) to gradually heat the reaction liquid, so that the temperature
of the reaction liquid is increased from 25.degree. C. to
83.degree. C. The air is compressed by the air compressor (30) and
then enters the horizontal generator (4) and stirs the reaction
liquid to make the reaction uniform while releasing and diluting
the chlorine dioxide gas; in addition, the blower (7) blows the air
into the horizontal generator (4) for further diluting the chlorine
dioxide gas concentration to 6% (V/V); the diluted chlorine dioxide
gas is sent out to the end use areas by the induced draft fan (8).
The product has a moisture content of 7.8% (w/w) and is essentially
free of chlorine.
[0032] Step 2, while the raw material enters into the horizontal
generator (4) from one end, the reacted reaction liquid is
discharged from the other end of the horizontal generator (4) to
the mother liquid discharge tank (9) for storage, and then sent to
the mother liquid lower circulating pipe (23) by the crystallizer
feed pump (10), and circulation, heating, evaporation and
concentration between the evaporation crystallizer (13) and the
heater (12) under the pumping action of the circulating pump (11);
the temperature in the evaporation crystallizer is controlled at
72.degree. C., the vacuum degree is controlled at -80 KPa(g). The
salt cake in the mother liquid is concentrated and crystallized and
is deposited at the bottom of the evaporation crystallizer (13) and
the lower circulating pipe (23) and sent to the filtration device
(15) through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate powder with dryness up to
99.65% (which can be sold as a byproduct); the filtrate liquid is
returned to the mother liquid circulating pipe (23) via the
filtrate pipe (22) for recycling. No solid and liquid wastes
produced throughout the production process.
[0033] Step 3, the clarified mother liquid in the upper of the
evaporation crystallizer (13) is sent to the mother liquid tank
(18) by the mother liquid extraction pump (17) for buffering, and
then sent to the horizontal generator (4) by the mother liquid
return pump (19).
EXAMPLE 3
[0034] As shown in FIG. 1, a device for producing high-purity
chlorine dioxide gas includes a horizontal generator (4), blower
(7), induced draft fan (8), mother liquid discharge tank (9),
crystallizer feed pump (10), circulating pump (11), heater (12),
evaporation crystallizer (13), filtration unit feed pump (14),
filtration unit (15), dryer (16), mother liquid extraction pump
(17), mother liquid tank (18), mother liquid return pump (19), air
compressor (30). The sulfuric acid pipe (1) is connected with the
horizontal generator (4); the hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and are connected to the horizontal
generator (4); the heat source pipe (5) is connected to the inlet
of the horizontal generator (4); the compressed air pipe (6) is
connected to the air compressor (30) and the horizontal generator
(4); the horizontal generator (4) is connected to the mother liquid
discharge tank (9) through a reaction liquid (mother liquid)
discharge pipe (25); the mother liquid discharge tank (9) is
connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and upper circulating
pipe (24) are connected with the evaporation crystallizer (13),
heater (12) and the circulating pump (11); the mother liquid tank
(18) is connected to the evaporation crystallizer (13) and the
horizontal generator (4) through the inlet/outlet pipe of the
mother liquid extraction pump (27) and the inlet/outlet pipe of the
mother liquid return pump (20); the heat source pipe (21) is
connected to the inlet pipe of the heater (12); the filtration unit
(15) is connected to the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe of the feed pump (28) and the
filtrate pipe (22) to form a circulation loop; the filtration unit
(15) is connected to the dryer (16) via the salt cake discharge
pipe (29).
[0035] The method for preparing 12 t/d chlorine dioxide gas using
the above mentioned device is as follows:
[0036] Step 1, sulfuric acid enters into the horizontal generator
(4) through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters into the horizontal
generator (4) after being mixed with the sodium chlorate in pipe
(3), chlorine dioxide gas is generated after the redox reaction.
The heat source enters the horizontal generator (4) through pipe
(5) to gradually heat the reaction liquid, so that the temperature
of the reaction liquid is increased from 30.degree. C. to
85.degree. C. The air is compressed by the air compressor (30) and
then enters the horizontal generator (4) and stirs the reaction
liquid to make the reaction uniform while releasing and diluting
the chlorine dioxide gas; in addition, the blower (7) blows the air
into the horizontal generator (4) for further diluting the chlorine
dioxide gas concentration to 9% (V/V); the diluted chlorine dioxide
gas is sent out to the end use areas by the induced draft fan (8).
The product has a moisture content of 7.5% (w/w) and is essentially
free of chlorine.
[0037] Step 2, while the raw material enters into the horizontal
generator (4) from one end, the reacted reaction liquid is
discharged from the other end of the horizontal generator (4) to
the mother liquid discharge tank (9) for storage, and then sent to
the mother liquid lower circulating pipe (23) by the crystallizer
feed pump (10), and circulation, heating, evaporation and
concentration between the evaporation crystallizer (13) and the
heater (12) under the pumping action of the circulating pump (11);
the temperature in the evaporation crystallizer is controlled at
70.degree. C., the vacuum degree is controlled at -81 KPa(g). The
salt cake in the mother liquid is concentrated and crystallized and
is deposited at the bottom of the evaporation crystallizer (13) and
the lower circulating pipe (23) and sent to the filtration device
(15) through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate with dryness up to 99.6%
(which can be sold as a product); the filtrate is returned to the
mother liquid circulating pipe (23) via the filtrate pipe (22) for
recycling. No solid and liquid wastes produced throughout the
production process.
[0038] Step 3, the clarified mother liquid in the upper of the
evaporation crystallizer (13) is sent to the mother liquid tank
(18) by the mother liquid extraction pump (17) for buffering, and
then sent to the horizontal generator (4) by the mother liquid
return pump (19).
[0039] It will be readily understood that the components of various
embodiments of the present invention, as generally described and
illustrated in the figures herein, may be arranged and designed in
a wide variety of different configurations. Thus, the detailed
description of the embodiments of the present invention, as
represented in the attached figures, is not intended to limit the
scope of the invention as claimed but is merely representative of
selected embodiments of the invention.
[0040] The features, structures, or characteristics of the
invention described throughout this specification may be combined
in any suitable manner in one or more embodiments. For example,
reference throughout this specification to "certain embodiments,"
"some embodiments," or similar language means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
present invention. Thus, appearances of the phrases "in certain
embodiments," "in some embodiment," "in other embodiments," or
similar language throughout this specification do not necessarily
all refer to the same group of embodiments and the described
features, structures, or characteristics may be combined in any
suitable manner in one or more embodiments.
[0041] It should be noted that reference throughout this
specification to features, advantages, or similar language does not
imply that all of the features and advantages that may be realized
with the present invention should be or are in any single
embodiment of the invention. Rather, language referring to the
features and advantages is understood to mean that a specific
feature, advantage, or characteristic described in connection with
an embodiment is included in at least one embodiment of the present
invention. Thus, discussion of the features and advantages, and
similar language, throughout this specification may, but do not
necessarily, refer to the same embodiment.
[0042] Furthermore, the described features, advantages, and
characteristics of the invention may be combined in any suitable
manner in one or more embodiments. One skilled in the relevant art
will recognize that the invention can be practiced without one or
more of the specific features or advantages of a particular
embodiment. In other instances, additional features and advantages
may be recognized in certain embodiments that may not be present in
all embodiments of the invention.
[0043] One having ordinary skill in the art will readily understand
that the invention as discussed above may be practiced with steps
in a different order, and/or with hardware elements in
configurations which are different than those which are disclosed.
Therefore, although the invention has been described based upon
these preferred embodiments, it would be apparent to those of skill
in the art that certain modifications, variations, and alternative
constructions would be apparent, while remaining within the spirit
and scope of the invention. In order to determine the metes and
bounds of the invention, therefore, reference should be made to the
appended claims.
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