JP3572744B2 - Exhaust gas treatment equipment containing high concentration sulfurous acid gas - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an exhaust gas treatment device containing high-concentration sulfurous acid gas.
[0002]
[Prior art]
Conventionally, limestone, ie, calcium carbonate (CaCO₃In general, as shown in FIG. 17, a wet-type flue gas desulfurization apparatus uses a spray nozzle 2 disposed at an upper portion by operating a circulating pump 3 to absorb an absorbent 2 from a liquid reservoir 1 formed at a lower portion. An absorption tower 5 for discharging exhaust gas supplied from a boiler or the like, not shown, into contact with the absorbing liquid 2 sprayed from the spray nozzle 4 and then discharging the exhaust gas as purified gas; The gypsum recovery unit 18 is configured to introduce a part of the absorbent 2 circulated in 5 and to recover the gypsum 19 from the part of the absorbent 2.
[0003]
The liquid reservoir 1 of the absorption tower 5 is connected to a compressor 6 for supplying air for oxidation, and a stirrer 7 for stirring the absorbent 2 in the liquid reservoir 1 is provided. In the pit 11, an absorbent 23 supplied from a mother liquor tank 25 described later and calcium carbonate 9 supplied from a silo 8 are kneaded to produce an absorbent slurry 10, and the absorbent slurry 10 The liquid is supplied to the reservoir 1.
[0004]
The gypsum recovery unit 18 is supplied with a neutralizing agent storage tank 26 in which the neutralizing agent 12 such as caustic soda (NaOH) is stored, and a part of the absorbing solution 2 circulated by the circulation pump 3. A neutralizing tank 13 to which the neutralizing agent 12 is supplied from a neutralizing agent storage tank 26 to mix and stir the absorbing solution 2 and the neutralizing agent 12, and a thickener 15 for concentrating the absorbing solution 14 extracted from the neutralizing tank 13. And a dehydrator supply tank 17 to which the absorbing liquid 16 concentrated by the thickener 15 is supplied and agitates the absorbing liquid 16, and the absorbing liquid 16 extracted from the dehydrating supply tank 17 is dehydrated to produce gypsum 19. , A filtrate pit 22 for supplying water 21 dewatered by the dehydrator 20 and supplying a part of the water 21 to the thickener 15, and a supernatant absorbent 23 from the thickener 15. Offering And a mother liquor tank 25 for supplying a part of the absorbent 23 to the liquid reservoir 1 of the absorption tower 5 and the absorbent slurry pit 11 and sending the remainder to a wastewater treatment device 24. ing.
[0005]
In the case of the above-mentioned wet flue gas desulfurization apparatus, the absorbing liquid 2 is circulated by the operation of the circulation pump 3, and the exhaust gas sent to the absorption tower 5 from a boiler or the like (not shown) is sprayed from the spray nozzle 4. After coming into contact with the absorbing liquid 2, the sulfur oxides are absorbed and removed, and then discharged to the outside as a purified gas.
[0006]
On the other hand, a part of the absorbent 2 having absorbed the sulfur oxides from the exhaust gas is supplied to the neutralization tank 13 constituting the gypsum recovery unit 18 from the middle of the circulation line by the circulation pump 3, Mixing and stirring with the neutralizing agent 12 supplied from the wetting agent storage tank 26, the mixed and stirred absorption liquid 14 is sent to the thickener 15, concentrated in the thickener 15, and the concentrated absorption liquid 16 is dewatered. It is sent to the dehydrator 20 via the supply tank 17, and the dehydrator 20 removes moisture to produce solid gypsum 19.
[0007]
The water 21 dehydrated by the dehydrator 20 is returned to the thickener 15 through a filtrate pit 22, and the supernatant absorbent 23 which is discharged when the absorbent 14 is concentrated in the thickener 15 passes through a mother liquor tank 25. The water is supplied to the liquid reservoir 1 and the absorbent slurry pit 11 of the absorption tower 5 and is also sent to a wastewater treatment device 24.
[0008]
The absorbent 23 supplied to the absorbent slurry pit 11 is kneaded with the calcium carbonate 9 supplied from the silo 8 in the absorbent slurry pit 11, and is absorbed in the liquid reservoir 1 of the absorption tower 5 as an absorbent slurry 10. Supplied.
[0009]
The absorbing liquid 23 sent to the wastewater treatment device 24 is discharged outside after harmful nitrogen compounds are decomposed by the action of nitrifying bacteria or the like of the wastewater treatment device 24.
[0010]
[Problems to be solved by the invention]
In the conventional wet type flue gas desulfurization apparatus as described above, the low concentration SO up to about 6000 [ppm] is used.₂Although it is suitable for treating exhaust gas, it has a high level of about 1 to 10%, which is discharged from a sulfur recovery unit in petroleum refining, including off-gas discharged from a regeneration tower of a desulfurization unit used for integrated coal gasification combined cycle. When it is intended to treat exhaust gas containing sulfur dioxide at a high concentration, it is difficult to obtain satisfactory desulfurization performance, as indicated by the phantom line in FIG. 9, and a large amount of scale is generated and adhered inside the absorption tower 5. There was a fear that it would.
[0011]
In view of such circumstances, the present invention is to provide a high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus capable of reliably performing desulfurization from exhaust gas containing high-concentration sulfurous acid gas and minimizing scale generation. It is assumed that.
[0012]
[Means for Solving the Problems]
In the present invention, the sulfur oxides are absorbed and removed by circulating the absorbent 2 containing calcium carbonate 9 as an absorbent from the lower reservoir 1 to the upper part and bringing the exhaust gas into contact with the absorbent 2. After that, an absorption tower 5 that is discharged to the outside as a purified gas,
A high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus comprising: a gypsum recovery unit 18 for introducing a part of the absorbent 2 circulated in the absorption tower 5 and recovering a gypsum 19 from a part of the absorbent 2 ,
A gas-liquid contact tray 27 which is arranged in a plurality of stages in the vertical direction above the liquid reservoir 1 in the absorption tower 5 and has a plurality of gas passage holes 34 each;
An absorbent slurry supply line 28 for supplying the absorbent slurry 10 onto the gas-liquid contact tray 27 of each stage;
A flow rate adjusting valve 29 for adjusting the flow rate of the absorbent slurry 10 supplied from the absorbent slurry supply line 28 of each stage onto the gas-liquid contact tray 27 of each stage;
A pH meter 30 for detecting the pH of the liquid on the gas-liquid contact tray 27 of each stage;
Based on the detection signal 30a from the pH meter 30 at each stage, an opening command signal 29a is output to the flow control valve 29 at each stage so that the pH of the liquid on the gas-liquid contact tray 27 at each stage becomes a set value. Controller 31
The present invention relates to an exhaust gas treatment device containing high-concentration sulfurous acid gas, comprising:
[0013]
Further, the present invention absorbs sulfur oxides by circulating an absorbent 2 containing calcium carbonate 9 as an absorbent from a lower reservoir 1 to an upper portion, and bringing exhaust gas into contact with the absorbent 2. After removal, an absorption tower 5 that is discharged to the outside as a purified gas;
A high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus comprising: a gypsum recovery unit 18 for introducing a part of the absorbent 2 circulated in the absorption tower 5 and recovering a gypsum 19 from a part of the absorbent 2 ,
A gas-liquid contact tray 27 which is arranged in a plurality of stages in the vertical direction above the liquid reservoir 1 in the absorption tower 5 and has a plurality of gas passage holes 34 each;
An absorbent slurry supply line 28 for supplying the absorbent slurry 10 onto the gas-liquid contact tray 27 of each stage;
A flow rate adjusting valve 29 for adjusting the flow rate of the absorbent slurry 10 supplied from the absorbent slurry supply line 28 of each stage onto the gas-liquid contact tray 27 of each stage;
An overall flow control valve 40 for adjusting the overall flow rate of the absorbent slurry 10 introduced into the absorbent slurry supply line 28 of each stage;
A pH meter 41 for detecting the pH of the liquid in the liquid reservoir 1 of the absorption tower 5,
Based on the detection signal 41a from the pH meter 41, an opening degree command signal 40a is output to the entire flow rate regulating valve 40 so that the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 becomes a set value, and at each stage, A controller 31 ′ that outputs an opening command signal 29 a ′ to the flow control valve 29 at each stage so that the flow rate of the absorbent slurry 10 supplied onto the gas-liquid contact tray 27 is proportionally distributed at a set ratio. When
The present invention relates to an exhaust gas treatment device containing high-concentration sulfurous acid gas, comprising:
[0014]
In the high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus, an oxidation tower 38 in which a part of the absorbent 2 circulated in the absorber 5 is introduced and oxidizes a part of the absorbent 2 and guides the oxidized part 2 to the gypsum recovery unit 18. Can be provided.
[0015]
Further, in the exhaust gas treatment apparatus containing high-concentration sulfurous acid gas, the exhaust gas sent into the absorption tower 5 and the purified gas discharged from the absorption tower 5 exchange heat, thereby cooling the exhaust gas and heating the purified gas. A purification gas heater 36 may be provided.
[0016]
Further, in the exhaust gas treatment device containing high-concentration sulfurous acid gas, a spray nozzle 4 for spraying the absorbent 2 may be provided at the top of the absorption tower 5.
[0017]
Furthermore, in the exhaust gas treatment device containing high-concentration sulfurous acid gas, an auxiliary absorption tower 5 ′ having a spray nozzle 4 ′ for spraying the absorbing liquid 2 disposed at the top can be provided on the outlet side of the absorption tower 5. .
[0018]
According to the above means, the following effects can be obtained.
[0019]
In the case of an exhaust gas treatment device containing a high-concentration sulfurous acid gas having a pH meter 30 for detecting the pH of the liquid on the gas-liquid contact tray 27 of each stage, during operation, 1 to 10% discharged from a sulfur recovery device or the like in petroleum refining during operation. Exhaust gas containing sulfur dioxide gas having a high concentration is sent to the absorption tower 5, the absorption liquid 2 is circulated, and the absorption liquid of each stage is placed on the gas-liquid contact tray 27 of each stage provided in the absorption tower 5. The absorbent slurry 10 is supplied from the absorbent slurry supply line 28, and at this time, the supply amount of the calcium carbonate slurry as the absorbent₂At the same time as being controlled according to the amount, the pH of the liquid on the gas-liquid contact tray 27 at each stage is detected by the pH meter 30 at each stage, and the controller is controlled based on a detection signal 30a from the pH meter 30 at each stage. An opening command signal 29a is output from 31 to the flow control valve 29 of each stage, and the pH of the liquid on the gas-liquid contact tray 27 of each stage is adjusted to a set value.
[0020]
The exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact trays 27 of the respective stages and rises in the process of absorbing the liquid 2 on the gas-liquid contact trays 27 of the respective stages. , The contact time between the absorbing solution 2 and the exhaust gas is prolonged, and after the sulfur oxide is reliably absorbed and removed, the sulfur oxide is discharged to the outside as a purified gas. By maintaining the pH of the liquid on the gas-liquid contact tray 27 at the set value, it is possible to prevent a large amount of scale from being generated and attached inside the absorption tower 5.
[0021]
In the case of an exhaust gas treatment device containing a high-concentration sulfurous acid gas having a pH meter 41 for detecting the pH of the liquid in the liquid reservoir 1 of the absorption tower 5, 1 to 10 discharged from a sulfur recovery device or the like in oil refining during operation. % Of sulfur dioxide gas is sent to the absorption tower 5, the absorption liquid 2 is circulated, and each stage is placed on the gas-liquid contact tray 27 arranged in the absorption tower 5. The absorbent slurry 10 is supplied from the absorbent slurry supply line 28. At this time, the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 is detected by the pH meter 41, and based on the detection signal 41a from the pH meter 41. The controller 31 'outputs an opening command signal 40a to the overall flow control valve 40, and the absorbent slurry supplied to the absorption tower 5 so that the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 becomes a set value. 10 While the overall flow rate is adjusted, the controller 31 'outputs an opening degree command signal 29a' to the flow rate control valve 29 of each stage, and the flow rate of the absorbent slurry 10 supplied onto the gas-liquid contact tray 27 of each stage. Are proportionally distributed at the set ratios.
[0022]
The exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact trays 27 of the respective stages and rises in the process of absorbing the liquid 2 on the gas-liquid contact trays 27 of the respective stages. , The contact time between the absorbing solution 2 and the exhaust gas is prolonged. After the sulfur oxide is reliably absorbed and removed, the sulfur oxide is discharged to the outside as a purified gas. The total flow rate of the absorbent slurry 10 supplied to the absorption tower 5 is adjusted so that the pH of the liquid in the liquid reservoir 1 becomes a set value, and the absorbent supplied to the gas-liquid contact tray 27 at each stage is adjusted. By proportionally distributing the flow rate of the slurry 10 at a set ratio, the pH of the liquid on the gas-liquid contact tray 27 at each stage is adjusted, and a large amount of scale is generated and adhered inside the absorption tower 5. Can be prevented That.
[0023]
In the exhaust gas treatment apparatus containing high-concentration sulfurous acid gas, a part of the absorbent 2 circulated in the absorption tower 5 is introduced and a part of the absorbent 2 is oxidized and led to the gypsum recovery unit 18. In the case where the absorption liquid 2 is not sufficiently oxidized in the liquid reservoir 1 of the absorption tower 5, part of the absorption liquid 2 is oxidized by the oxidation tower 38 to recover gypsum. It can lead to the unit 18.
[0024]
Further, in the high-concentration sulfurous acid gas-containing exhaust gas treatment device, heat exchange is performed between the exhaust gas sent into the absorption tower 5 and the purified gas discharged from the absorption tower 5, thereby cooling the exhaust gas and heating the purified gas. If the purified gas heater 36 is provided, the exhaust gas sent into the absorption tower 5 exchanges heat with the purified gas discharged from the absorption tower 5 by the purified gas heater 36, and is cooled to some extent before being introduced into the absorption tower 5. Therefore, the dry-up phenomenon does not easily occur, and the scale does not easily adhere to the inside of the absorption tower 5.
[0025]
In the exhaust gas treatment device containing high-concentration sulfurous acid gas, a spray nozzle 4 for spraying the absorbing liquid 2 is provided at the top of the absorption tower 5. In the process of ascending through the gas passage holes 34 of the contact tray 27, the absorbent 2 is sequentially contacted with the absorbent 2 on the gas-liquid contact tray 27 of each stage, and then further sprayed from the spray nozzle 4. The contact time between the absorbing liquid 2 and the exhaust gas is further extended by contact with the sulfuric acid, and the sulfur oxide is reliably absorbed and removed.
[0026]
Further, in the exhaust gas treatment apparatus containing high-concentration sulfurous acid gas, an auxiliary absorption tower 5 ′ having a spray nozzle 4 ′ for spraying the absorbing liquid 2 ′ is provided on the outlet side of the absorption tower 5. Exhaust gas sent to the step 5 comes in contact with the absorbing liquid 2 on the gas-liquid contact tray 27 of each stage in the process of rising through the gas passage holes 34 of the gas-liquid contact tray 27 of each stage. As a result, the contact time between the absorbing liquid 2 and the exhaust gas is prolonged, and after the sulfur oxide is reliably absorbed and removed, the sulfur oxide is introduced into the auxiliary absorption tower 5 ′, and sprayed in the auxiliary absorption tower 5 ′. The sulfur oxide is absorbed and removed by further contacting with the absorbing liquid 2 'sprayed from the nozzle 4'.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
FIG. 1 is an example of an embodiment of the present invention, in which parts denoted by the same reference numerals as those in FIG. 17 represent the same parts, and the basic configuration is the same as that of the conventional one shown in FIG. However, as shown in FIG. 1, the gas-liquid contact tray 27 is arranged in a plurality of vertical stages (three stages in the illustrated example) above the liquid reservoir 1 in the absorption tower 5 as shown in FIG. The absorbent slurry supply line 28 for supplying and supplying the absorbent slurry 10 onto the gas-liquid contact tray 27 of each stage is formed in a branch, and the gas-liquid contact tray of each stage is connected from the absorbent slurry supply line 28 of each stage. A flow rate control valve 29 for adjusting the flow rate of the absorbent slurry 10 supplied onto the liquid supply tray 27; a pH meter 30 for detecting the pH of the liquid on the gas-liquid contact tray 27 at each stage; Based on the detection signal 30a from the total 30, the gas-liquid contact As the pH of the liquid on the Lee 27 is respectively set value lies in providing the controller 31 which outputs an opening degree command signal 29a to the flow control valve 29 of each stage.
[0029]
As the gas-liquid contact tray 27, as shown in FIGS. 2 and 3, a plurality of gas passage holes 34 for flowing exhaust gas are formed in a disc 33 having a notch 32 formed on an edge thereof. A sheave tray in which a downcomer 35 that overflows while retaining the liquid on the disk 33 and guides the liquid to the lower stage is attached to the portion 32 can be used. As the gas-liquid contact tray 27, instead of a sheave tray as shown in FIGS. 2 and 3, a simple disk 33 is used as shown in FIGS. A sieve tray provided with the gas passage holes 34 can also be used. As the gas-liquid contact tray 27, a valve tray having a movable valve 43 along a valve guide 42 as shown in FIGS. 6 and 7, or a number of angle members 44 as shown in FIG. An angle tray can be used.
[0030]
Further, in the illustrated example, a purified gas heater 36 for exchanging heat between the exhaust gas sent into the absorption tower 5 and the purified gas discharged from the absorption tower 5 to cool the exhaust gas and heat the purified gas is provided. is there.
[0031]
Next, the operation of the illustrated example will be described.
[0032]
During operation, exhaust gas containing a high concentration of about 1 to 10% of sulfurous acid gas discharged from a sulfur recovery device or the like in petroleum refining is sent to the absorption tower 5, and the absorption liquid 2 is circulated by the operation of the circulation pump 3, In addition, the absorbent slurry 10 is supplied from the absorbent slurry supply line 28 of each stage onto the gas-liquid contact tray 27 of each stage disposed in the absorption tower 5. The pH of the liquid on the gas-liquid contact tray 27 at each stage is detected, and based on a detection signal 30a from the pH meter 30 at each stage, an opening command signal 29a is output from the controller 31 to the flow control valve 29 at each stage. Then, the pH of the liquid on the gas-liquid contact tray 27 in each stage is adjusted so as to be a set value.
[0033]
The exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact trays 27 of the respective stages and rises in the process of absorbing the liquid 2 on the gas-liquid contact trays 27 of the respective stages. The contact time between the absorbing liquid 2 and the exhaust gas is extended by successive contact with the sulfuric acid, and after the sulfur oxide is reliably absorbed and removed, the sulfur oxide is discharged to the outside as a purified gas. The SO contained in the exhaust gas₂The relationship between the concentration and the desulfurization rate was as shown by the solid line in FIG. 9, as an experimental result.
[0034]
Further, by maintaining the pH of the liquid on the gas-liquid contact tray 27 of each stage at a set value, it is possible to prevent a large amount of scale from being generated and attached inside the absorption tower 5.
[0035]
Here, the set value of the pH of the liquid on the gas-liquid contact tray 27 in each of the stages is set to gradually decrease from the upper stage to the lower stage. For example, the set value of the pH of the liquid on the upper gas-liquid contact tray 27 is set. To about 5.8, the set value of the liquid pH on the middle gas-liquid contact tray 27 to about 4.8, and the set value of the liquid pH on the lower gas-liquid contact tray 27 to about 4.0. It was obtained as an experimental result that it is desirable to perform each.
[0036]
Furthermore, when the temperature of the exhaust gas sent into the absorption tower 5 is high, the inside of the absorption tower 5 dries, that is, a so-called dry-up phenomenon occurs, and the scale easily adheres to the inside of the absorption tower 5. The exhaust gas sent into the absorption tower 5 exchanges heat with the purified gas discharged from the absorption tower 5 by the purified gas heater 36, and is introduced into the absorption tower 5 after being cooled to some extent. This makes it difficult for the scale to adhere to the inside of the absorption tower 5.
[0037]
In this way, desulfurization from exhaust gas containing high-concentration sulfurous acid gas can be reliably performed, and generation of scale can be minimized. The present apparatus is particularly suitable for desulfurization from exhaust gas containing high-concentration sulfur dioxide gas, but can be applied to the treatment of exhaust gas having a sulfur dioxide gas concentration of about 5000 [ppm] or more. .
[0038]
In the example of the embodiment of the present invention shown in FIG. 1 described above, when the oxidation of the absorbing liquid 2 in the liquid reservoir 1 of the absorption tower 5 is not sufficiently performed, as shown in FIG. An oxidizing tower 38 is provided in which a part of the absorbing liquid 2 circulated in the absorbing tower 5 is introduced and a part of the absorbing liquid 2 is oxidized by the oxidizing air 37 and led to the neutralization tank 13 of the gypsum collecting unit 18. I do. In FIG. 10, the reason why the exhaust gas flowing out of the oxidation tower 38 is returned to the inlet side of the absorption tower 5 is that the sulfur gas may be contained in the exhaust gas. This is because desulfurization is performed by returning to the inlet side. In FIG. 10, reference numeral 39 denotes sulfuric acid which is appropriately charged into the oxidation tower 38 as needed.
[0039]
Further, in one example of the embodiment of the present invention shown in FIG. 1 described above, as shown in FIG. 11, a spray nozzle 4 for spraying the absorbing liquid 2 is provided at the top of the absorption tower 5. Is also good.
[0040]
As described above, when the spray nozzle 4 for spraying the absorbing liquid 2 is provided at the top of the absorption tower 5, the exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact tray 27 at each stage. In the process of passing and rising, the absorbent liquid 2 comes into contact with the absorbing liquid 2 on the gas-liquid contact tray 27 of each of the above stages, and then comes into contact with the absorbing liquid 2 sprayed from the spray nozzle 4, whereby the absorbing liquid 2 2, the contact time between the exhaust gas and the exhaust gas is further extended, and the sulfur oxide is reliably absorbed and removed.
[0041]
Further, in an example of the embodiment of the present invention shown in FIG. 1 described above, a spray nozzle 4 ′ for spraying the absorbing liquid 2 ′ is provided at the top on the outlet side of the absorption tower 5 as shown in FIG. The provided auxiliary absorption tower 5 'may be provided.
[0042]
As described above, when the auxiliary absorption tower 5 'in which the spray nozzle 4' for spraying the absorbing liquid 2 'is provided at the top on the outlet side of the absorption tower 5, the exhaust gas sent to the absorption tower 5 is In the process of ascending through the gas passage holes 34 of the gas-liquid contact trays 27 of the stages, the absorbents 2 are successively brought into contact with the absorbents 2 on the gas-liquid contact trays 27 of the stages so that After the contact time with the exhaust gas is prolonged and the sulfur oxides are surely absorbed and removed, the liquid is introduced into the auxiliary absorption tower 5 'and sprayed from the spray nozzle 4' in the auxiliary absorption tower 5 ' Further contact with 2 'absorbs and removes sulfur oxides.
[0043]
FIG. 13 shows another example of the embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. The liquid contact trays 27 are arranged in a plurality of stages in the vertical direction (four stages in the example in the figure), and an absorbent slurry supply line 28 for supplying the absorbent slurry 10 onto the gas-liquid contact trays 27 in each stage is branched and formed. A flow control valve 29 for adjusting the flow rate of the absorbent slurry 10 supplied from the absorbent slurry supply line 28 of each stage onto the gas-liquid contact tray 27 of each stage is provided. An overall flow control valve 40 for adjusting the overall flow rate of the introduced absorbent slurry 10 is provided, and a pH meter 41 for detecting the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 is provided. Based on the detection signal 41a, the liquid in the absorption tower 5 The opening degree command signal 40a is output to the overall flow rate control valve 40 so that the pH of the liquid in the storage unit 1 becomes a set value, and the flow rate of the absorbent slurry 10 supplied onto the gas-liquid contact tray 27 at each stage is adjusted. A controller 31 ′ that outputs an opening degree command signal 29 a ′ is provided at each stage of the flow rate adjusting valve 29 so as to be proportionally distributed at the set ratio.
[0044]
In the example shown in FIG. 13, at the time of operation, exhaust gas containing high-concentration sulfurous acid gas of about 1 to 10% discharged from a sulfur recovery device or the like in petroleum refining is sent to the absorption tower 5 and the absorbent 2 is circulated. The absorbent slurry 10 is supplied from the absorbent slurry supply line 28 of each stage to the gas-liquid contact tray 27 of each stage which is circulated by the operation of the pump 3 and disposed in the absorption tower 5. The pH of the liquid in the liquid reservoir 1 of the absorption tower 5 is detected by the pH meter 41, and the opening command signal 40 a is output from the controller 31 ′ to the overall flow control valve 40 based on the detection signal 41 a from the pH meter 41. The total flow rate of the absorbent slurry 10 supplied to the absorption tower 5 is adjusted so that the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 becomes a set value, and the flow rate of each stage is controlled by the controller 31 ′. Adjustment 29 opening command signal 29a 'is output to the flow rate of the absorbent slurry 10 supplied to the gas-liquid contact tray 27 on the respective stages are prorated ratios are respectively set.
[0045]
The exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact tray 27 of each stage and rises in the same manner as in the example shown in FIG. By sequentially contacting the absorbing liquid 2 on the gas-liquid contact tray 27, the contact time between the absorbing liquid 2 and the exhaust gas is extended, and after the sulfur oxide is reliably absorbed and removed, the purified gas is used as a purified gas. It is discharged outside.
[0046]
In addition, the total flow rate of the absorbent slurry 10 supplied to the absorption tower 5 is adjusted so that the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 becomes a set value, and the liquid slurry is transferred onto the gas-liquid contact tray 27 of each stage. By proportionally distributing the flow rate of the supplied absorbent slurry 10 at a set ratio, the pH of the liquid on the gas-liquid contact tray 27 at each stage is adjusted, and a large amount of scale is formed inside the absorption tower 5. Generation and adhesion are prevented.
[0047]
Here, the set value of the pH of the liquid in the liquid reservoir 1 of the absorption tower 5 is about 4 to 5, and the total flow rate of the absorbent slurry 10 supplied to the absorption tower 5 at that time is Q₀And the flow rate of the absorbent slurry 10 supplied onto the gas-liquid contact tray 27 at each stage is sequentially changed from the upper stage to Q₁, Q₂, Q₃, Q₄If, for example,
(Equation 1)
Q₁= 0.5Q₀
Q₂= 0.3Q₀
Q₃= 0.1Q₀
Q₄= 0.1Q₀
What is necessary is just to set the ratio of each stage as follows.
[0048]
Further, also in the example shown in FIG. 13, the exhaust gas sent into the absorption tower 5 exchanges heat with the purified gas discharged from the absorption tower 5 by the purified gas heater 36 and is cooled to a certain extent before being introduced into the absorption tower 5. Therefore, the dry-up phenomenon does not easily occur, and the scale does not easily adhere to the inside of the absorption tower 5.
[0049]
Thus, as in the example shown in FIG. 1, in the example shown in FIG. 13, desulfurization from the exhaust gas containing the high-concentration sulfurous acid gas can be reliably performed, and the generation of scale can be minimized. The present apparatus is particularly suitable for desulfurization from exhaust gas containing high-concentration sulfur dioxide gas, but can be applied to the treatment of exhaust gas having a sulfur dioxide gas concentration of about 5000 [ppm] or more. .
[0050]
In another example of the embodiment of the present invention shown in FIG. 13 described above, when oxidation of the absorbing liquid 2 in the liquid reservoir 1 of the absorption tower 5 is not sufficiently performed, the state shown in FIG. As described above, an oxidation tower 38 is provided in which a part of the absorption liquid 2 circulated in the absorption tower 5 is introduced, and a part of the absorption liquid 2 is oxidized by the oxidizing air 37 and led to the neutralization tank 13 of the gypsum recovery unit 18. To do. Note that, in FIG. 14, portions denoted by the same reference numerals as in FIG. 10 represent the same items.
[0051]
In another example of the embodiment of the present invention shown in FIG. 13 described above, as shown in FIG. 15, a spray nozzle 4 for spraying the absorbing liquid 2 is provided at the top of the absorption tower 5. It may be.
[0052]
As described above, when the spray nozzle 4 for spraying the absorbing liquid 2 is provided at the top of the absorption tower 5, the exhaust gas sent to the absorption tower 5 passes through the gas passage holes 34 of the gas-liquid contact tray 27 at each stage. In the process of passing and rising, the absorbent liquid 2 comes into contact with the absorbing liquid 2 on the gas-liquid contact tray 27 of each of the above stages, and then comes into contact with the absorbing liquid 2 sprayed from the spray nozzle 4, whereby the absorbing liquid 2 2, the contact time between the exhaust gas and the exhaust gas is further extended, and the sulfur oxide is reliably absorbed and removed.
[0053]
Further, in another example of the embodiment of the present invention shown in FIG. 13 described above, as shown in FIG. 16, a spray nozzle 4 ′ for spraying the absorbent 2 ′ is provided at the outlet side of the absorption tower 5. May be provided.
[0054]
As described above, when the auxiliary absorption tower 5 'in which the spray nozzle 4' for spraying the absorbing liquid 2 'is provided at the top on the outlet side of the absorption tower 5, the exhaust gas sent to the absorption tower 5 is In the process of ascending through the gas passage holes 34 of the gas-liquid contact trays 27 of the stages, the absorbents 2 are successively brought into contact with the absorbents 2 on the gas-liquid contact trays 27 of the stages so that After the contact time with the exhaust gas is prolonged and the sulfur oxides are surely absorbed and removed, the liquid is introduced into the auxiliary absorption tower 5 'and sprayed from the spray nozzle 4' in the auxiliary absorption tower 5 ' Further contact with 2 'absorbs and removes sulfur oxides.
[0055]
The high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus of the present invention is not limited to the above-described illustrated example, and various changes can be made without departing from the scope of the present invention.
[0056]
【The invention's effect】
As described above, according to the high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus according to claims 1 to 6 of the present invention, desulfurization from exhaust gas containing high-concentration sulfurous acid gas can be reliably performed, and scale An excellent effect that generation can be minimized can be achieved.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.
FIG. 2 is a side sectional view showing an example in which a sheave tray with a downcomer is used as a gas-liquid contact tray in an example of an embodiment of the present invention.
FIG. 3 is a sectional view taken along the line III-III of FIG. 2;
FIG. 4 is a side sectional view illustrating an example in which a sheave tray without a downcomer is used as a gas-liquid contact tray in an example of an embodiment of the present invention.
FIG. 5 is a sectional view taken along line VV of FIG. 4;
FIG. 6 is a side sectional view showing an example in which a valve tray is used as a gas-liquid contact tray in an example of an embodiment of the present invention.
FIG. 7 is a view taken along the line VII-VII in FIG. 6;
FIG. 8 is a side sectional view showing an example in which an angle tray is used as a gas-liquid contact tray in an example of an embodiment of the present invention.
FIG. 9 SO in exhaust gas₂It is a diagram showing the relationship between the concentration and the desulfurization rate.
FIG. 10 is an overall schematic configuration diagram when an oxidation tower is separately provided in an example of an embodiment of the present invention.
FIG. 11 is an overall schematic configuration diagram in a case where a spray nozzle is provided at the top in an absorption tower in an example of an embodiment of the present invention.
FIG. 12 is an overall schematic configuration diagram when an auxiliary absorption tower is provided in an example of an embodiment of the present invention.
FIG. 13 is an overall schematic configuration diagram of another example of an embodiment of the present invention.
FIG. 14 is an overall schematic configuration diagram in another example of an embodiment of the present invention in which an oxidation tower is separately provided.
FIG. 15 is an overall schematic configuration diagram in a case where a spray nozzle is provided at the top in an absorption tower in another example of an embodiment of the present invention.
FIG. 16 is an overall schematic configuration diagram in a case where an auxiliary absorption tower is provided in another example of the embodiment of the present invention.
FIG. 17 is an overall schematic configuration diagram of a conventional example.
[Explanation of symbols]
1 Liquid pool
2 Absorbent
2 'absorbing liquid
4 spray nozzle
4 'spray nozzle
5 Absorption tower
5 'auxiliary absorption tower
9 calcium carbonate
10 Absorbent slurry
18 Gypsum collection unit
19 plaster
27 Gas-liquid contact tray
28 Absorbent slurry supply line
29 Flow control valve
29a Opening command signal
29a 'Opening degree command signal
30 pH meter
30a Detection signal
31 Controller
31 'controller
34 Gas passage hole
36 Purified gas heater
38 Oxidation tower
40 Total flow control valve
40a Opening command signal
41 pH meter
41a Detection signal

Claims (6)

An absorbing solution (2) containing calcium carbonate (9) as an absorbing agent is circulated from a lower reservoir (1) to an upper portion, and the exhaust gas to be sent is brought into contact with the absorbing solution (2), whereby sulfur oxides are formed. An absorption tower (5) for discharging as a purified gas after absorbing and removing
A gypsum recovery unit (18) for introducing a part of the absorbent (2) circulated in the absorption tower (5) and for recovering gypsum (19) from a part of the absorbent (2). An exhaust gas treatment device containing a concentration of sulfurous acid gas,
A gas-liquid contact tray (27), which is disposed in a plurality of stages in the vertical direction above the liquid reservoir (1) in the absorption tower (5) and has a plurality of holes (34) each;
An absorbent slurry supply line (28) for supplying the absorbent slurry (10) onto the gas-liquid contact tray (27) of each stage;
A flow control valve (29) for adjusting a flow rate of the absorbent slurry (10) supplied from the absorbent slurry supply line (28) of each stage onto the gas-liquid contact tray (27) of each stage;
A pH meter (30) for detecting the pH of the liquid on the gas-liquid contact tray (27) at each stage;
Based on the detection signal (30a) from the pH meter (30) at each stage, the flow rate adjusting valve (29) at each stage such that the pH of the liquid on the gas-liquid contact tray (27) at each stage becomes a set value. And a controller (31) for outputting an opening command signal (29a). An absorbing solution (2) containing calcium carbonate (9) as an absorbing agent is circulated from a lower reservoir (1) to an upper portion, and the exhaust gas to be sent is brought into contact with the absorbing solution (2), whereby sulfur oxides are formed. An absorption tower (5) for discharging as a purified gas after absorbing and removing
A gypsum recovery unit (18) for introducing a part of the absorbent (2) circulated in the absorption tower (5) and for recovering gypsum (19) from a part of the absorbent (2). An exhaust gas treatment device containing a concentration of sulfurous acid gas,
A gas-liquid contact tray (27) which is disposed in a plurality of stages in the vertical direction above the liquid reservoir (1) in the absorption tower (5) and has a plurality of gas passage holes (34) each;
An absorbent slurry supply line (28) for supplying the absorbent slurry (10) onto the gas-liquid contact tray (27) of each stage;
A flow control valve (29) for adjusting a flow rate of the absorbent slurry (10) supplied from the absorbent slurry supply line (28) of each stage onto the gas-liquid contact tray (27) of each stage;
An overall flow control valve (40) for adjusting the overall flow rate of the absorbent slurry (10) introduced into the absorbent slurry supply line (28) of each stage;
A pH meter (41) for detecting the pH of the liquid in the liquid reservoir (1) of the absorption tower (5);
Based on the detection signal (41a) from the pH meter (41), an opening command is issued to the overall flow rate regulating valve (40) so that the pH of the liquid in the liquid reservoir (1) of the absorption tower (5) becomes a set value. A signal (40a) is output, and the flow rate of each stage is adjusted so that the flow rate of the absorbent slurry (10) supplied onto the gas-liquid contact tray (27) of each stage is proportionally distributed at a set ratio. An exhaust gas treatment device containing high-concentration sulfurous acid gas, comprising: a controller (31 ') for outputting an opening command signal (29a') to a valve (29). There is provided an oxidation tower (38) into which a part of the absorbing liquid (2) circulated in the absorption tower (5) is introduced, and a part of the absorbing liquid (2) is oxidized and led to the gypsum recovery unit (18). 3. The exhaust gas treatment device according to claim 1 or 2, wherein the exhaust gas treatment device contains a high concentration of sulfurous acid gas. A purification gas heater (36) for exchanging heat between the exhaust gas sent into the absorption tower (5) and the purified gas discharged from the absorption tower (5) to cool the exhaust gas and heat the purified gas. 4. The exhaust gas treatment device according to claim 1, 2 or 3, wherein the exhaust gas treatment device contains a high-concentration sulfurous acid gas. The high-concentration sulfurous acid gas-containing exhaust gas treatment apparatus according to claim 1, 2, 3, or 4, wherein a spray nozzle (4) for spraying the absorbing liquid (2) is provided at a top portion in the absorption tower (5). An auxiliary absorption tower (5 ') provided on the outlet side of the absorption tower (5) with a spray nozzle (4') for spraying an absorption liquid (2 ') provided at the top. 4. An exhaust gas treatment apparatus containing a high concentration of sulfurous acid gas according to 4.

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