CN103072956B - Flue gas processing method and system - Google Patents
Flue gas processing method and system Download PDFInfo
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- CN103072956B CN103072956B CN201210589997.XA CN201210589997A CN103072956B CN 103072956 B CN103072956 B CN 103072956B CN 201210589997 A CN201210589997 A CN 201210589997A CN 103072956 B CN103072956 B CN 103072956B
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- 239000003546 flue gas Substances 0.000 title claims abstract description 353
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 344
- 238000003672 processing method Methods 0.000 title abstract 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims abstract description 189
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 claims abstract description 100
- 238000000034 method Methods 0.000 claims abstract description 77
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 46
- 238000002156 mixing Methods 0.000 claims abstract description 22
- 235000010269 sulphur dioxide Nutrition 0.000 claims description 81
- 238000006243 chemical reaction Methods 0.000 claims description 51
- 238000010521 absorption reaction Methods 0.000 claims description 23
- 238000010438 heat treatment Methods 0.000 claims description 21
- 239000002253 acid Substances 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 10
- 238000007865 diluting Methods 0.000 claims description 9
- 238000010790 dilution Methods 0.000 claims description 7
- 239000012895 dilution Substances 0.000 claims description 7
- 239000004291 sulphur dioxide Substances 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 27
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 238000003723 Smelting Methods 0.000 description 14
- 230000008901 benefit Effects 0.000 description 12
- 239000007789 gas Substances 0.000 description 11
- 239000003054 catalyst Substances 0.000 description 9
- 238000011084 recovery Methods 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000000779 smoke Substances 0.000 description 5
- 239000002918 waste heat Substances 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 4
- 230000023556 desulfurization Effects 0.000 description 4
- 238000006057 reforming reaction Methods 0.000 description 4
- 238000007605 air drying Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000009856 non-ferrous metallurgy Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Treating Waste Gases (AREA)
Abstract
The invention discloses a flue gas processing method and system. The method comprises the following steps: dividing flue gas to be processed into a first flue gas and a second flue gas; utilizing the air to dilute the first flue gas, so as to allow the concentration of the sulfur dioxide to be lower than 12 (volume) percent; converting at least some sulfur dioxide in the diluted first flue gas into sulfur trioxide, so as to obtain the first flue gas containing both the sulfur trioxide and the sulfur dioxide; mixing the first flue gas containing both the sulfur trioxide and the sulfur dioxide with the second flue gas, so as to obtain a mixed flue gas, wherein the sulfur dioxide concentration of the mixed flue gas is lower than 12.5 (volume) percent; and utilizing the mixed flue gas to prepare sulfuric acid. The method can effectively process the flue gas with higher sulfur dioxide content, and the equivalent concentration of the sulfur dioxide of the processed flue gas is up to 17 (volume) percent. The method is simple, low in energy consumption and cost, high in flue gas processing efficiency, strong in suitability and flexible in operation.
Description
Technical Field
The invention relates to a method and a system for treating flue gas.
Background
In the field of acid making by smelting flue gas, with the development of oxygen-enriched smelting technology of nonferrous metallurgy, the concentration of sulfur dioxide in the flue gas entering a flue gas acid making system is up to more than 20%. If a conventional sulfur dioxide conversion process is used, the sulfur dioxide concentration needs to be diluted to about 12% to ensure that the temperature after the reaction does not exceed the tolerance temperature of the catalyst and the converter material. Even if the inlet temperature is reduced by using a low-temperature cesium catalyst, the concentration of sulfur dioxide in the flue gas cannot exceed 14%. This results in an increase in the scale of the conversion and its subsequent equipment, which leads to a large increase in the investment and operating costs of the entire acid plant, and affects the improvement in the overall economic efficiency due to the progress of the smelting process. Therefore, an economical and effective high-concentration sulfur dioxide conversion process becomes a hot topic of research in the field of acid making from smelting flue gas. The high-concentration sulfur dioxide conversion technology adopted at home and abroad at present mainly comprises flue gas circulation, an isothermal reactor and unbalanced high-concentration SO2The two-transformation technology and the like are mostly in the starting stage, and have advantages and disadvantages in the aspects of technical level and economic benefit.
Therefore, the flue gas treatment conversion process with high sulfur dioxide concentration still needs to be improved at the present stage.
Disclosure of Invention
The present invention aims to solve at least one of the above technical problems to at least some extent or to at least provide a useful commercial choice. Therefore, the invention aims to provide a method which has the advantages of low cost, simple process, strong adaptability and flexible operation and can effectively treat the flue gas containing high-concentration sulfur dioxide.
To this end, according to one aspect of the invention, a method of treating flue gas is provided. According to an embodiment of the invention, the method comprises: dividing the flue gas to be treated into a first flue gas and a second flue gas; diluting the first flue gas with air to reduce the sulfur dioxide concentration to 12 vol%; converting at least a portion of sulfur dioxide in the diluted first flue gas to sulfur trioxide to obtain a first flue gas containing sulfur trioxide and sulfur dioxide; mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas to obtain a mixed flue gas, wherein the concentration of the sulfur dioxide in the mixed flue gas is less than 12.5 vol%; and using the mixed flue gas for preparing sulfuric acid.
The inventor surprisingly finds that the flue gas treatment method can effectively realize the treatment of the flue gas with high sulfur dioxide content, the equivalent concentration of sulfur dioxide in the treated flue gas can reach up to 17 volume percent, and the flue gas treatment method has the advantages of simple process, low energy consumption and cost, high flue gas treatment efficiency, strong adaptability and flexible operation. Specifically, according to the embodiment of the invention, the method for treating the flue gas can reduce the flue gas amount entering the acid making device by 20-30%, and reduce the operation cost by 15-20%. It should be noted that the "equivalent concentration" of sulfur dioxide in the flue gas treated in this document is calculated by the following formula: sulfur dioxide equivalent concentration in treated flue gas "= SO in flue gas to be treated2The amount of the first flue gas + the amount of air diluting the first flue gas + the amount of the second flue gas), wherein the amount of each gas in the above formula can be expressed in terms of its volume. Therefore, by the formula, the equivalent concentration of the sulfur dioxide in the flue gas which can be treated by the flue gas treatment method can be calculated, so that the equivalent concentration can be compared with the concentration of the sulfur dioxide in the flue gas which can be treated by the conventional two-rotation two-absorption method (the flue gas of which the sulfur dioxide is diluted to about 12 vol%). According to some embodiments of the invention, the method of treating flue gas of the invention is capable of treating flue gas having a sulfur dioxide "normality" of up to 17% by volume. Therefore, the method for treating the smoke has remarkable superiority.
In addition, the method for treating the flue gas has the following additional technical characteristics:
according to one embodiment of the invention, the flue gas to be treated is preheated in advance to reach a temperature of 250-350 ℃ before being divided into a first flue gas and a second flue gas. Therefore, the flue gas is preliminarily heated, and the subsequent steps are facilitated.
According to one embodiment of the invention, the diluted first flue gas is heated to 380-420 ℃ before at least a part of the sulfur dioxide in the diluted first flue gas is converted into sulfur trioxide. The flue gases thus reach the temperature required for the pre-reforming reaction.
According to one embodiment of the invention, the mixed flue gas is used for the preparation of sulfuric acid by a two-turn two-absorption process. Therefore, the efficiency of flue gas treatment and sulfuric acid preparation can be effectively improved.
According to one embodiment of the invention, the first flue gas containing sulfur trioxide and sulfur dioxide is cooled and the second flue gas is preheated before being mixed with the first flue gas containing sulfur trioxide and sulfur dioxide. Therefore, the first flue gas and the second flue gas can reach the temperature required by the conventional conversion layer reaction.
According to another aspect of the invention, there is also provided a system for treating flue gas. According to an embodiment of the invention, the system comprises: the flue gas shunting device is used for dividing flue gas to be treated into first flue gas and second flue gas; a dilution device connected to the flue gas diversion device to dilute the first flue gas with air to reduce the sulfur dioxide concentration to 12 vol%; the pre-conversion device is connected with the diluting device and is used for converting at least part of sulfur dioxide in the diluted first flue gas into sulfur trioxide so as to obtain a first flue gas containing sulfur trioxide and sulfur dioxide; the mixing device is respectively connected with the flue gas diversion device and the pre-conversion device and is used for mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas so as to obtain mixed flue gas, wherein the concentration of the sulfur dioxide in the mixed flue gas is less than 12.5 vol%; and the acid making device is connected with the mixing device and is used for preparing sulfuric acid by using the mixed flue gas.
The inventor surprisingly finds that the system for treating the flue gas can effectively treat the flue gas with high sulfur dioxide concentration, the equivalent concentration of sulfur dioxide in the treated flue gas can reach 17 volume percent, and the system for treating the flue gas has the advantages of simple structure and process flow, small occupied area, low cost, less energy consumption, high heat recovery rate, good flue gas treatment effect, strong adaptability and flexible operation. Specifically, according to the embodiment of the invention, the system for treating the flue gas can reduce the amount of the flue gas entering the acid making device by 20-30% and reduce the operation cost by 15-20%.
In addition, the system for treating flue gas of the invention has the following additional technical features:
according to an embodiment of the invention, the system for treating flue gas further comprises a first heating device, wherein the first heating device is connected with the flue gas diversion device and used for preheating the flue gas to be treated in advance before the flue gas to be treated is divided into the first flue gas and the second flue gas so as to reach the temperature of 250-350 ℃. Therefore, the flue gas is preliminarily heated, and the subsequent steps are facilitated.
According to an embodiment of the invention, the method further comprises a second heating device, wherein the second heating device is respectively connected with the diluting device and the pre-conversion device and is used for heating the diluted first flue gas to 380-420 ℃ before converting at least a part of sulfur dioxide in the diluted first flue gas into sulfur trioxide. Thus, the flue gas can reach the temperature required by the pre-reforming reaction.
According to one embodiment of the invention, the acid making apparatus is adapted to prepare sulfuric acid using a two-turn two-absorption process. Therefore, the efficiency of flue gas treatment and sulfuric acid preparation can be effectively improved.
According to one embodiment of the invention, the system for treating flue gas of the invention further comprises: the cooling device is respectively connected with the pre-conversion device and the mixing device and is used for cooling the first flue gas containing the sulfur trioxide and the sulfur dioxide before the first flue gas containing the sulfur trioxide and the sulfur dioxide is mixed with the second flue gas; and the third heating device is respectively connected with the flue gas diversion device and the mixing device and is used for preheating the second flue gas before the first flue gas containing sulfur trioxide and sulfur dioxide is mixed with the second flue gas. Therefore, the first flue gas and the second flue gas can reach the temperature required by the conventional conversion layer reaction.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 shows a schematic flow diagram of a method of treating flue gas according to one embodiment of the invention;
FIG. 2 shows a schematic block diagram of a system for treating flue gas according to one embodiment of the present invention;
FIG. 3 shows a process flow diagram of a method of treating flue gas according to one embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
According to one aspect of the invention, a method of treating flue gas is provided. According to the embodiment of the invention, the method for treating the flue gas can effectively treat the flue gas with high sulfur dioxide content, the equivalent concentration of sulfur dioxide in the treated flue gas can reach up to 17 volume percent, and the method has the advantages of simple process, low energy consumption and cost, high flue gas treatment efficiency, strong adaptability and flexible operation. Specifically, according to the embodiment of the invention, the method for treating the flue gas can reduce the flue gas amount entering the acid making device by 20-30%, and reduce the operation cost by 15-20%.
For ease of understanding, the method of treating flue gas of the present invention is described in detail below with reference to fig. 1.
According to an embodiment of the invention, referring to fig. 1, the method of treating flue gas of the invention may comprise:
s100: flue gas diversion
Firstly, the flue gas to be treated is divided into a first flue gas and a second flue gas. According to the embodiment of the present invention, the apparatus for dividing the flue gas to be treated into the first flue gas and the second flue gas is not particularly limited as long as the flue gas split can be achieved. For example, two paths can be laid to divide the flue gas into a first flue gas and a second flue gas, and the flow of the flue gas can be controlled by using the gas dividing valve. According to one embodiment of the invention, the flue gas to be treated may be preheated in advance to reach a temperature of 250-350 ℃ before being divided into the first flue gas and the second flue gas. Therefore, the flue gas is preliminarily heated, and the subsequent steps are facilitated. Among them, according to the embodiment of the present invention, the apparatus for preheating the flue gas to be treated is not particularly limited. According to one embodiment of the invention, a heat exchanger may be used to preheat the flue gas to be treated.
S200: dilution of
Secondly, the first flue gas is diluted with air in order to reduce the sulphur dioxide concentration to 12% by volume. According to the embodiment of the invention, the first flue gas can be diluted by utilizing dry air, so that the efficiency of diluting the first flue gas can be effectively improved. Among them, the method of obtaining the dry air is not particularly limited. According to one embodiment of the present invention, the dried air may be obtained by passing the air through an air blower and an air drying tower in this order.
S300: pre-transformation
At least a portion of the sulfur dioxide in the diluted first flue gas is then converted to sulfur trioxide to yield a first flue gas comprising sulfur trioxide and sulfur dioxide. According to the embodiment of the invention, the diluted first flue gas can be passed through the pre-converter provided with the catalyst layer, so that at least a part of sulfur dioxide in the diluted first flue gas can be oxidized and converted into sulfur trioxide. Furthermore, according to an embodiment of the present invention, the diluted first flue gas may be warmed to 380-420 ℃ before converting at least a portion of the sulfur dioxide in the diluted first flue gas to sulfur trioxide. The flue gases thus reach the temperature required for the pre-reforming reaction. Wherein, the device for heating the diluted first flue gas is not particularly limited. According to one embodiment of the invention, the diluted first flue gas may be passed through a heat exchanger, so that it can be efficiently warmed to the aforementioned temperature.
S400: flue gas mixing
Next, the first flue gas containing sulfur trioxide and sulfur dioxide obtained above is mixed with the second flue gas to obtain a mixed flue gas, wherein the concentration of sulfur dioxide in the mixed flue gas is below 12.5 vol%. It should be noted that the concentration of sulfur dioxide in the first flue gas containing sulfur trioxide and sulfur dioxide is very low, so that after the first flue gas is mixed with the second flue gas having a higher concentration of sulfur dioxide, the concentration of sulfur dioxide in the mixed flue gas can be lower, and can reach below 12.5 vol%.
Furthermore, according to an embodiment of the invention, the first flue gas containing sulfur trioxide and sulfur dioxide may be cooled and the second flue gas preheated before being mixed with the first flue gas containing sulfur trioxide and sulfur dioxide. Therefore, the first flue gas and the second flue gas can reach the temperature required by the conventional conversion layer reaction. The equipment for cooling the first flue gas containing sulfur trioxide and sulfur dioxide is not particularly limited. According to one embodiment of the invention, the first flue gas comprising sulphur trioxide and sulphur dioxide may be cooled with a heat exchanger.
S500: preparation of sulfuric acid
Then, the mixed flue gas obtained in the above way is used for preparing sulfuric acid. In particular, according to one embodiment of the present invention, the mixed flue gas can be used for preparing sulfuric acid by a two-turn two-absorption method. Therefore, the efficiency of flue gas treatment and sulfuric acid preparation can be effectively improved.
According to the embodiment of the invention, when the method for treating the flue gas is implemented, a plurality of waste heat boilers can be arranged in the process of using the obtained mixed flue gas for preparing the sulfuric acid, so that heat can be recovered from high-temperature gas as far as possible, the energy consumption is reduced, and the cost is reduced.
According to another aspect of the invention, there is also provided a system for treating flue gas. According to an embodiment of the invention, the system may comprise: flue gas diverging device, diluting device, pre-conversion device, mixing arrangement and system sour device.
For ease of understanding, the system for treating flue gas of the present invention is described in detail below with reference to fig. 2 and 3.
According to an embodiment of the invention, referring to fig. 2, the system 1000 for treating flue gas of the invention may comprise: a flue gas diversion device 100, a dilution device 200, a pre-conversion device 300, a mixing device 400 and an acid making device 500. According to some embodiments of the invention, the flue gas splitting device 100 is configured to split the flue gas to be treated into a first flue gas and a second flue gas; the dilution device 200 is connected to the flue gas splitting device 100 to dilute the first flue gas with air to reduce the sulfur dioxide concentration to 12 vol%; the pre-conversion device 300 is connected with the dilution device 200 and is used for converting at least a part of sulfur dioxide in the diluted first flue gas into sulfur trioxide so as to obtain a first flue gas containing sulfur trioxide and sulfur dioxide; the mixing device 400 is respectively connected with the flue gas diversion device 100 and the pre-conversion device 300, and is used for mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas so as to obtain a mixed flue gas, wherein the concentration of the sulfur dioxide in the mixed flue gas is below 12.5 vol%; the acid making device 500 is connected with the mixing device 400 and is used for preparing sulfuric acid by using the mixed flue gas.
The inventor surprisingly finds that the system for treating the flue gas can effectively treat the flue gas with high sulfur dioxide concentration, the equivalent concentration of sulfur dioxide in the treated flue gas is up to 17 volume percent, and the system for treating the flue gas has the advantages of simple structure and process flow, small occupied area, low cost, less energy consumption, high heat recovery rate, good flue gas treatment effect, strong adaptability and flexible operation. Specifically, according to the embodiment of the invention, the system for treating the flue gas can reduce the amount of the flue gas entering the acid making device by 20-30% and reduce the operation cost by 15-20%.
Furthermore, according to an embodiment of the present invention, the system 1000 for treating flue gas of the present invention may further comprise a first heating device (not shown in the figures). According to the embodiment of the invention, the first heating device is connected with the flue gas diversion device 100 and is used for preheating the flue gas to be treated in advance before the flue gas to be treated is divided into the first flue gas and the second flue gas so as to reach the temperature of 250-350 ℃. Therefore, the flue gas is preliminarily heated, and the subsequent steps are facilitated.
According to another embodiment of the present invention, the system 1000 for treating flue gas of the present invention may further comprise a second heating device (not shown in the figures). According to an embodiment of the invention, the second heating device is connected to the dilution device 200 and the pre-conversion device 300 respectively, and is used for heating the diluted first flue gas to 380-420 ℃ before converting at least a part of sulfur dioxide in the diluted first flue gas into sulfur trioxide. The flue gases thus reach the temperature required for the pre-reforming reaction.
In the system 1000 for treating flue gas of the present invention, the acid making apparatus 500 is adapted to prepare sulfuric acid using a two-turn two-absorption method according to one embodiment of the present invention. Therefore, the efficiency of flue gas treatment and sulfuric acid preparation can be effectively improved.
According to yet another embodiment of the invention, the system 1000 for treating flue gas of the invention may further comprise: a cooling device (not shown in the figure) connected to the pre-conversion device 300 and the mixing device 400, respectively, for cooling the first flue gas containing sulfur trioxide and sulfur dioxide before mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas; and a third heating device, which is respectively connected with the flue gas diversion device 100 and the mixing device 400, and is used for preheating the second flue gas before the first flue gas containing sulfur trioxide and sulfur dioxide is mixed with the second flue gas. Therefore, the first flue gas and the second flue gas can reach the temperature required by the conventional conversion layer reaction.
Furthermore, according to an embodiment of the present invention, the method for treating flue gas according to the present invention can be utilized by referring to a schematic process flow diagram shown in FIG. 3 (wherein, as shown in FIG. 3, 1-main blower, 2-fourth heat exchanger, 3-first heat exchanger, 4-air blower, 5-air drying tower, 6-preheat exchanger, 7-pre-converter, 8-main converter, 9-1 exhaust-heat boiler, 10-1 exhaust-heat boiler drum, 11-second heat exchanger, 12-third heat exchanger, 13-2 exhaust-heat boiler, 14-2 exhaust-heat boiler drum, 15-3 exhaust-heat boiler, 16-3 exhaust-heat boiler drum, 17-1 air distribution valve, 18-2 air distribution valve, A-flue gas from drying tower, B-air, C-to first absorption tower, D-to first absorption tower, E-to second absorption tower flue gas, F-boiler feed water, G-steam), the method comprises the following specific steps:
the method comprises the following steps that smoke to be treated passes through a main blower 1 and then enters a fourth heat exchanger 2 to be preheated so as to be divided into first smoke and second smoke by two pipelines after reaching the temperature of 250-350 ℃, and the flow is controlled by gas separating valves 17 and 18 respectively;
the air is passed through an air blower 4 and an air drying tower 5 in order to obtain dried air. Then, dry air is mixed with the first flue gas SO as to dilute the first flue gas, and SO is added2The concentration was reduced to about 12 vol%. And then, feeding the diluted first flue gas into a shell side of a preheating exchange unit 6 (located in a pre-converter 7), heating to 380-420 ℃, and feeding the first flue gas into the pre-converter 7. Wherein, a catalyst layer is arranged in the pre-converter 7, SO that at least a part of SO in the first diluted flue gas (the flue gas temperature does not exceed the catalyst tolerance temperature of 630 ℃) after temperature rise can be ensured2Conversion to SO3SO as to obtain a product containing SO3And SO2The first flue gas of (a). Then, the SO is contained3And SO2The first flue gas enters a preheating heat exchanger 6 (positioned in a pre-converter 7) to be cooled on a tube side;
the second flue gas enters the shell side of the first heat exchanger 3 (positioned in the main converter 8) for preheating, and then is cooled at the outlet of the tube side of the preheating exchanger 6 and contains SO3And SO2SO as to obtain a mixed flue gas, wherein SO is contained in the mixed flue gas2The concentration of (A) is 12.5% or less. Then, the mixed flue gas is used for preparing sulfuric acid by a two-rotation two-absorption method, specifically: the mixed flue gas enters the first catalyst layer of the main converter 8 SO as to lead at least part of SO in the mixed flue gas2Conversion to SO3Obtaining the mixed flue gas after the first conversion, then enabling the mixed flue gas after the first conversion to enter a No. 1 waste heat boiler 9 so as to recover heat, and then entering a first heat exchanger 3 (positioned in a main converter 8) for further cooling on a tube side; then, the cooled mixed flue gas after the first conversion enters the second catalyst layer of the main converter 8, SO as to make at least part of SO in the cooled mixed flue gas after the first conversion2Conversion to SO3Obtaining the mixed flue gas after the second conversion and leading the mixed flue gas to enter the second conversionThe tube side of the two heat exchangers 11 (located in the main converter 8) enters the third catalyst layer of the main converter 8 after being cooled, so as to obtain the third converted mixed flue gas. Similarly, the mixed flue gas after the third conversion enters a third heat exchanger 12 for tube pass cooling, then enters a No. 2 waste heat boiler 13 for further heat recovery, and is sent to a first absorption tower for preparing sulfuric acid;
then absorbing SO by a first absorption tower3SO remaining thereafter2The flue gas returns, enters a third heat exchanger 12 shell side and a second heat exchanger 11 (positioned in the main converter 8) shell side in sequence for preheating, and enters the preheated and heated flue gas into a fourth catalyst layer of the main converter 8 SO as to ensure that at least part of SO in the flue gas is2Conversion to SO3And the gas enters the fourth heat exchanger 2 for cooling, then enters a No. 3 waste heat boiler 15 for further heat recovery, and then is sent to a second absorption tower for preparing sulfuric acid.
It should be noted that in the above-mentioned process for treating flue gas according to an embodiment of the present invention as shown in fig. 3, the preheating device 6 is disposed inside the pre-converter 7 (which functions as the pre-converter 300 shown in fig. 2 of the present invention), the first heat exchanger 3 and the second heat exchanger 11 are disposed inside the main converter 8, and the combined conversion system adopts a central cylinder structure; the pre-converter 7 is combined with the main converter 8 and is arranged at the upper part of the main converter 8; the two-conversion and two-absorption adopts an external heat exchange process of IV I-III II, and 3 waste heat boilers are respectively arranged at the outlet of one layer of the main converter 8, the primary conversion flue gas side and the secondary conversion flue gas side to recover heat, so that the occupied area and the investment can be effectively saved, the heat can be effectively recovered, the energy consumption can be reduced, and the cost can be reduced. In addition, it should be noted that the process for treating flue gas according to one embodiment of the present invention shown in fig. 3 can flexibly adapt to the flue gas amount and SO of the flue gas to be treated2High or low concentration of SO, e.g. in flue gas to be treated2When the concentration is lower than 12%, the gas separating valve 17 and the devices for treating the first flue gas can be closed, namely the flue gas to be treated does not need to be subjected to flue gas flow separation and pretreatmentThe conversion can be directly carried out to prepare sulfuric acid and treat flue gas by a two-conversion and two-absorption method; when SO is in the flue gas to be treated2When the concentration is higher than 12%, all the devices can be started, and the flue gas is firstly shunted and pre-converted.
The scheme of the invention will be explained with reference to the examples. It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Example 1
Smelting flue gas (SO) for certain copper smelting project in Sichuan2The concentration is as high as 27.69 volume percent, and the smoke amount is about 90143Nm3H), comparing the cost, efficiency and effect of treating the flue gas by using the conventional two-rotation two-absorption process and the method for treating the flue gas, the method comprises the following steps:
as is well known, when the smelting flue gas is treated by adopting the conventional two-rotation two-absorption process, SO enters into a layer of conversion2The concentration is generally controlled to be about 12 vol%, i.e. the smelting flue gas must be diluted to about 208000Nm by adding a large amount of air at the inlet of the drying tower3H can be derived from SO2And (5) sending the air into a conversion working section by a fan. Moreover, the equipment scale of the whole conversion and dry absorption section of the process is very large, especially the SO used as the main power equipment of the acid making system2The fan power reaches 4150 kW.
Referring to the schematic process flow diagram shown in FIG. 3, when the smelting flue gas is treated by the method for treating flue gas of the present invention, undiluted smelting flue gas passes through SO2The fan enters the fourth heat exchanger 2 and the fan power can be reduced to about 2000 kW. The temperature of the smelting flue gas is raised to about 320 ℃ after being preheated by the fourth heat exchanger 2, and then the smelting flue gas is divided into two paths: a first flue gas and a second flue gas. Wherein a small amount of air is added into the first flue gas to make SO2The concentration is diluted to 12 vol%, then the temperature is further raised to about 390 ℃ through a preheating heat exchanger 6, and the SO enters a pre-converter 7 to enable most of SO to be subjected to oxidation reaction2Conversion to SO3To obtain a solution containing SO3And SO2Then cooled to around 420 c by the preheat exchanger 6. The second flue gas is further heated to about 420 ℃ by the first heat exchanger 3 and then mixed with the cooled SO-containing flue gas3And SO2So as to obtain a mixed flue gas. Due to the SO contained3And SO2SO in the first flue gas2The concentration is lower, and after being mixed with the second flue gas, the SO in the mixed flue gas2Can be reduced to about 10 volume percent, thereby meeting the requirement of the conventional two-rotation and two-suction. Then, the mixed flue gas can enter the main converter 8, and the conversion and absorption of the flue gas are completed according to a '3 + 1' two-rotation two-absorption process flow (not described herein again). Theoretical calculation shows that when the method for treating the smelting flue gas is used for treating the smelting flue gas, the total conversion rate can reach 99.94 percent, SO that tail emission SO of the project can be ensured2The concentration is less than or equal to 400mg/Nm3And meets the latest national environmental protection requirements.
Comparing the cost, efficiency and effect of treating the flue gas by using the conventional two-rotation two-absorption process and the method for treating the flue gas, in particular to SO (SO) of the treated flue gas estimated from theory2Concentration, entering SO2The flue gas amount of the fan, the flue gas amount entering the converter, the occupied area of equipment, the specification and the number of the equipment and the tail gas emission SO2The concentration, the recovery of saturated steam of 2.5MPa, the total operation cost and the total investment are carried out, and the specific comparison results are shown in the following table:
as can be seen from the above table, although the method of the present invention is used and the conventional two-rotation and two-suction technique is usedThe investment cost is basically equivalent, but the scheme of the invention has more advantages in view of the operation cost. This is because, although the scheme of the present invention is employed, SO2Total power consumption of fan and air fan and SO produced by conventional two-rotation and two-suction process2The power consumption of the blower is not much different, but the power consumption of a circulating pump in a dry-suction section is obviously less than that of the conventional two-rotation two-suction process. Moreover, when the conventional two-conversion and two-absorption process is adopted, the tail gas desulfurization device must operate for a long time, and when the scheme of the invention is adopted, although the tail gas desulfurization device is also needed, the tail gas desulfurization device is only used in abnormal states such as driving and accidents, and the operation cost of tail gas desulfurization is greatly reduced. In addition, the scheme of the invention has more advantages in aspects of equipment floor space, tail row indexes and heat recovery (namely, 2.5MPa of saturated steam recovery). The method for treating the flue gas can reduce the amount of the flue gas entering the acid making device by 20-30% and reduce the operation cost by 15-20%.
Therefore, the method provided by the invention can be used for effectively treating the flue gas with high sulfur dioxide concentration, has the advantages of simple process, small occupied area, low cost, less energy consumption, high heat recovery rate, good flue gas treatment effect, strong adaptability and flexible operation, and is applied to production.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (4)
1. A method of treating flue gas, comprising:
dividing the flue gas to be treated into a first flue gas and a second flue gas;
diluting the first flue gas with air to reduce the sulfur dioxide concentration to 12 vol%;
converting at least a portion of sulfur dioxide in the diluted first flue gas to sulfur trioxide to obtain a first flue gas containing sulfur trioxide and sulfur dioxide;
mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas to obtain a mixed flue gas, wherein the concentration of the sulfur dioxide in the mixed flue gas is less than 12.5 vol%; and
the mixed flue gas is used for preparing sulfuric acid,
wherein,
the mixed flue gas is used for preparing sulfuric acid by a two-rotation two-absorption method,
preheating the flue gas to be treated in advance before the flue gas to be treated is divided into a first flue gas and a second flue gas so as to reach the temperature of 250-350 ℃,
heating the diluted first flue gas to 380-420 ℃ before converting at least a part of sulfur dioxide in the diluted first flue gas into sulfur trioxide.
2. The method according to claim 1, characterized in that the first flue gas containing sulphur trioxide and sulphur dioxide is cooled and the second flue gas is preheated before being mixed with the first flue gas containing sulphur trioxide and sulphur dioxide.
3. A system for treating flue gas, comprising:
the flue gas shunting device is used for dividing flue gas to be treated into first flue gas and second flue gas;
a dilution device connected to the flue gas diversion device to dilute the first flue gas with air to reduce the sulfur dioxide concentration to 12 vol%;
the pre-conversion device is connected with the diluting device and is used for converting at least part of sulfur dioxide in the diluted first flue gas into sulfur trioxide so as to obtain a first flue gas containing sulfur trioxide and sulfur dioxide;
the mixing device is respectively connected with the flue gas diversion device and the pre-conversion device and is used for mixing the first flue gas containing sulfur trioxide and sulfur dioxide with the second flue gas so as to obtain mixed flue gas, wherein the concentration of the sulfur dioxide in the mixed flue gas is less than 12.5 vol%; and
the acid making device is connected with the mixing device and is used for preparing sulfuric acid by utilizing the mixed flue gas,
the acid making device is suitable for preparing sulfuric acid by using a two-rotation two-absorption method,
wherein,
the flue gas treatment device further comprises a first heating device, wherein the first heating device is connected with the flue gas distribution device and is used for preheating the flue gas to be treated in advance before the flue gas to be treated is divided into a first flue gas and a second flue gas so as to reach the temperature of 250-350 ℃,
the device further comprises a second heating device, wherein the second heating device is respectively connected with the diluting device and the pre-conversion device and is used for heating the diluted first flue gas to 380-420 ℃ before converting at least a part of sulfur dioxide in the diluted first flue gas into sulfur trioxide.
4. The system of claim 3, further comprising:
the cooling device is respectively connected with the pre-conversion device and the mixing device and is used for cooling the first flue gas containing the sulfur trioxide and the sulfur dioxide before the first flue gas containing the sulfur trioxide and the sulfur dioxide is mixed with the second flue gas; and
and the third heating device is respectively connected with the flue gas diversion device and the mixing device and used for preheating the second flue gas before the first flue gas containing sulfur trioxide and sulfur dioxide is mixed with the second flue gas.
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| EP3075434A1 (en) * | 2015-04-02 | 2016-10-05 | Bayer Technology Services GmbH | Continuous method for the purification of gases containing so2 |
| CN106915731B (en) * | 2017-04-14 | 2023-08-08 | 双盾环境科技有限公司 | Adjustable high-concentration SO (SO) treatment by using inert catalyst 2 SO production by flue gas 3 Device for gas |
| CN109095441B (en) * | 2017-06-20 | 2022-01-07 | 中国瑞林工程技术股份有限公司 | Process for preparing sulfuric acid |
| CN107840313A (en) * | 2017-11-28 | 2018-03-27 | 江苏田润化工设备有限公司 | A kind of high concentration SO2Flue gas converts the method and device of extracting sulfuric acid |
| CN108046221B (en) * | 2017-12-12 | 2020-10-02 | 中国恩菲工程技术有限公司 | Method for preparing acid by smelting flue gas |
| CN109761203B (en) * | 2019-03-04 | 2021-07-02 | 长沙有色冶金设计研究院有限公司 | High-concentration SO2Conversion acid-making process |
| CN114572939A (en) * | 2022-04-01 | 2022-06-03 | 陕西莹钰化工设备有限公司 | Original SO2Technology for preparing sulfuric acid by partial pre-conversion |
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