JPS6018206B2 - Wet removal method for specific components contained in gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a wet removal method for specific components contained in gas, and more specifically to a leak shelf consisting of a perforated plate or a lattice plate without a weir or overflow part. at least one step or more,
By using a gas-liquid contact device loaded into the device,
The present invention relates to a method for wet removal of specific components contained in gas, that is, specific gas components, specific solid components, etc. contained in gas.

PRIOR ART Normally, wet methods for removing specific components contained in gas include methods using packed towers, spray towers, bubble towers, etc., and methods using a perforated plate with an aperture ratio of 0.3 or less. A method is generally known in which a gas to be treated and a treatment liquid are brought into contact with each other in a countercurrent manner using a perforated plate tower.

However, in the method using a packed tower, uneven flow tends to occur in the gas to be treated and the treatment liquid introduced into the packed tower, and furthermore, when the gas to be treated contains solid components such as soot and dust in the treatment liquid. However, this method has the disadvantage that the inside of the packed column is blocked and cannot be operated for a long period of time.

In addition, not only does the spray tower require a considerable amount of power to atomize the processing liquid, but a considerable amount of the processing liquid may be splashed into the gas to be treated and carried out of the equipment, or the spray tower may not be able to handle the process properly. It has the disadvantage that specific components contained in the gas cannot be efficiently removed. On the other hand, methods using devices equipped with trays such as a bubble tower or the above-mentioned perforated plate have a large pressure loss, and furthermore, the efficiency of each tray is low, so that certain components contained in the gas to be treated cannot be contained. It has the disadvantage that it cannot be removed efficiently. Moreover, the superficial velocity of the gas to be treated in the column is approximately 0.3 to 2 h.
/sec, so in order to process a large amount of gas, a device with a large column diameter is required. On the other hand, in Japanese Patent Publication No. 51-31036, Mr. Uchiyama et al. proposed that in order to avoid the above-mentioned drawbacks, "a Sekiguchi ratio of 25 to 60% (expressed as an aperture ratio of 0.25 to 0.6 )
By using a leakage shelf tower comprising at least one stage of leakage shelf having At column speed, the ratio of the flow rate L of the absorption liquid to the flow rate G of the gas to be treated L/G
``A method for absorbing specific gas components in a gas to be treated and/or removing fine dust, which is characterized by bringing the gas to be treated and an absorption liquid into contact with each other in a countercurrent manner so that the ing. Here, Mr. Uchiyama et al. define the gas superficial velocity at the upper limit point as Ugm, and further define the gas superficial velocity at the overflow point as Ugc, and show the calculation formula. That is, the invention of Mr. Uchiyama et al. adopts a gas superficial velocity between Ugm and Ugc based on the calculation formula defined in Japanese Patent Publication No. 51-31036, and furthermore, the flow rate L of the absorption liquid is set between 1 pi and 1 pi.
This paper proposes a method for selecting from the range of 1×1 pick9/〆hr. Therefore, the present inventors became interested in the invention of Mr. Uchiyama et al. and conducted an experiment to confirm the invention. However, although the invention of Mr. Uchiyama et al. can avoid the above-mentioned drawbacks to a certain extent, it is difficult to process a large amount of gas to be treated, for example, gas of 10,000 N/hr or more on an industrial scale. It was found that this was not very practical and was issued. Purpose and Structure of the Invention The present invention has been made as a result of intensive research based on the above knowledge.To further add, Mr. Uchiyama et al. reported in Japanese Patent Publication No. 51-31036 that the pressure loss rapidly increases. Then, an abnormal phenomenon occurred, and luck was no longer stable.・This paper proposes a method for efficiently removing specific components contained in gas by employing a gas superficial velocity exceeding the overflow point, that is, Ugc, at which it is known that conversion cannot be carried out.

That is, the method for removing specific components contained in gas according to the present invention consists of a leakage shelf tower having a tower diameter of 50 nm or more, which is loaded with at least one stage of leakage shelves having an open area ratio Fc of 0.3 to 0.6. The processing liquid is applied from the upper part of the gas-liquid contact device to the flow rate L(
The ratio L to G of k9/de・hr) is 0.5 or more, and the flow rate L of the processing liquid is 1 pi to 11×1 k9/〆・hr.
and introducing the gas to be treated from the lower part of the contacting device so that the gas superficial velocity Ug in the device is in the range of 1 blood/sec from Ugc defined below. This is characterized by bringing the gas to be processed and the processing liquid into countercurrent gas-liquid contact.

DETAILED DESCRIPTION OF THE INVENTION The above-mentioned Ugc according to the present invention is given by the following formula, and the formula '1} is expressed as follows: When the flow rate L of the processing liquid is 1 pi to 6 x 1 pi k9/hr, '2) The formula is applied when the flow rate L of the processing liquid is 6×1 pi to 11×1 pi k9/hr.

Ugc=3.434L-.・Go. 7.Ugm
...{1) Ugc=750.9L-.

・5704・Ugm...[2' Here, the above [1} and '21 formula are displayed as a function of Ugm, but Ugm can be defined by the following (3' formula to ■ formula. In formulas {3} to '6}, y is the capillary constant filtration bow g, and g is the acceleration of gravity (m/s
ec2) and the surface tension (k9/sec2) of the treatment liquid. a. Using a leakage shelf made of a perforated plate, the density p of the gas to be treated is determined relative to the density p of the processing liquid (k9/).
The ratio of g (kg/) is 0.838×10-3
If it is more than that.

Ugmi49・Sail.

・7・(Shizuka×Sail-0・5・(ki)-su.nog.evening...
'3'b Using a leakage shelf made of a perforated plate, the density of the gas to be treated pg (k
9/m) ratio pg/pso is less than 0.838×103.

Ugm=40.9 is C.

・7 (Kisu) - Fence ・(Mosu. Nog. So...'4'c
A leakage shelf consisting of a grid plate is used, and the density of the processing liquid p〆(k
When the ratio pg/p〆 of the density pg (k9/m) of the gas to be treated to the density pg (k9/m) is 1.20×10-3 or more.

Ugm = 67 Misaki (Shibu The ratio pg/p of the density pg (k9/〆) of the gas to be treated is 1.20×10
-If it is less than 3.

Ugm=76.7FC・(Sama X sail-・255・(Poison)
-0 enemy no g. So. ... [6' The gas-liquid contact device, which is used in the method of the present invention and is equipped with at least zero stages of leakage shelves, is a perforated plate or a lattice plate that does not have a weir or an overflow point. A leakage shelf consisting of 1 to 7 tiers, more preferably 3 to 5 tiers, 0.3 to 1.5 tiers, preferably 0.
Preferably, the gas-liquid contacting device is loaded into the device with a spacing of 5 to 1.2 kites.

Further, the closing ratio Fc of the leaky shelf is desirably selected from the range of 0.3 to 0.6, more preferably 0.32 to 0.52, and the hole diameter is selected from the range of 4 to 3 ribs. It is desirable to select. In this case, if the Sekiguchi ratio of the leakage shelf is made smaller than 0.3, it becomes impossible to make the gas superficial velocity Ug of the gas to be treated in the apparatus at least 3 h/sec or more, so it is necessary to increase the size of the apparatus. Then,
Furthermore, if the open ratio is larger than 0.6, a considerable amount of the processing liquid will scatter into the gas to be processed and will be easily carried out of the apparatus, so why should a larger amount of processing liquid be used than necessary? This is required. Furthermore, it is extremely difficult to manufacture a leakage shelf with a Sekiguchi ratio of 0.6 or more on an industrial scale due to manufacturing problems. Furthermore, in the present invention, the diameter of the leakage shelf column constituting the gas-liquid contact device must be 500 mm or more. If the diameter of the leaking shelf column is less than 50 m, it is not preferable because an overflow phenomenon will occur under the gas-liquid contact conditions specified in the present invention. Further, according to the method of the present invention, the flow rate G of the gas to be treated is
The ratio L/G of the flow rate L of the processing liquid to the flow rate L of the processing liquid is at least 0.
5 or more, preferably in the range of 1.0 to 6.0, and at least 1.5 or more, preferably 2.0 when the flow rate L of the processing liquid is 6 x 1 to 11 x 1 pk9/〆hr. It is desirable to select from the range of 20 to 20.

In this case, if the above-mentioned L/G is less than 0.5 and 1.5, respectively, the pressure loss not only increases but also the gas-liquid contact efficiency decreases significantly. Further, according to the method of the present invention, the above-mentioned superficial gas velocity is 3.43 mm-〇-〇8〆Ugm when the flow rate L of the processing liquid is 1 to 6×1 kg/〆・hr.
It is desirable to select from the range of IQh/sec (m/sec), but it is desirable that the upper limit is h/sec, more preferably ah/sec.

Similarly, the flow rate L of the processing liquid is 6×1 pik to 11×1 pik.
Even in the case of 9/hr, it is 750. Rainbow-o.57.U
It is preferable to select from a range of 1 h/sec from gm, but the upper limit is am/sec, more preferably 8 h/sec.
It is desirable to set it to sec.

In this case, if the gas superficial velocity is set to 1 h/sec or more, not only will the pressure loss increase, but the processing liquid will easily splash into the gas to be processed and be entrained outside the apparatus, resulting in stability. Unable to perform continuous operation. still,
The gas to be treated in the method of the present invention includes exhaust gas containing specific components such as harmful components such as sulfur oxides, nitrogen oxides, and/or soot dust, or various odorous components, or acid gas components and/or Examples include coke oven gas containing specific components such as ammonia, but the present invention is not only applicable to the treatment of these gases.
It is applied in all cases where it is necessary to remove specific components contained in gas, such as specific gas components and specific solid components. Additionally, the present invention can be used to cool or heat gases. However, the present invention is particularly suitable for removing the above-mentioned harmful components contained in exhaust gas. In this case, the processing liquid for processing the above-mentioned gas to be processed must match the properties of the specific components to be removed contained in the processing gas, but at least the above-mentioned specific components must be used. absorption liquid that can chemically absorb
Alternatively, it can be said that it is a cleaning solution that can physically remove it. For example, when removing sulfur oxides and/or nitrogen oxides contained in exhaust gas, absorbents such as alkali metal, alkali metal or ammonia hydroxides, and their carbonates and sulfites are used. ,
For example, an aqueous solution or suspension of one or more absorbents selected from the group of sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, magnesium carbonate, magnesium hydroxide, calcium carbonate, and calcium hydroxide. A liquid or the like is used as an absorbing liquid. In addition, when removing acidic gas components such as hydrogen sulfide contained in coke oven gas, ammonia water is used, and when further removing ammonia contained in the gas, sulfuric acid, phosphoric acid, carbolic acid,
An aqueous solution of an absorbent selected from the group of acetic acid, oxalic acid, and acidic ammonium phosphate is used as the absorbing liquid. On the other hand, when removing solid components such as soot and dust contained in exhaust gas, water or water containing a surfactant is used as a cleaning liquid, but it does not remove sulfur oxides and/or nitrogen oxides contained in the gas. Since the above-mentioned absorbing liquid used for this purpose also acts as a so-called cleaning liquid, it is not necessarily necessary to use the above-mentioned water as a cleaning liquid when such specific components are to be removed at the same time. Hereinafter, the constituent elements of the present invention will be explained in more detail based on FIG.

FIG. 1 shows the processing liquid L (k9/pillow/hr ) and the gas empty space Ug (mnosec). In Figure 1, area A is 3103
Ugm and U history and L obtained by the approximate calculation formula of Publication No. 6
/G=0.5 indicates the driving operation area, and area B-
1, B-2 and B-3 are the processing liquid flow rate in the present invention from 1 pm to 6 x 1 pm k9/force/hr, and from 6 x 1 to 11 x 1 pm
g/de・hr and 11×1 and over to 17×1 and k9/〆・
It is a drawing which shows the driving|operation area|region corresponding to hr. In addition,
FIG. 1 shows the case where Fc=0.32, pg=1.05k9/〆 and pso=1070k9/. Examples are shown below. Example 1 Using two gas-liquid contactors each with a tower diameter of 560 m and each equipped with three stages of leakage shelves consisting of perforated plates with aperture ratios of 0.32 and 0.52, air was heated under the conditions shown below. and water were brought into contact with each other in a countercurrent manner, and the amount of water contained in the air discharged from the device was measured.

Flow rate L of supply water: 1 to 11 x 1 kg/hr Ratio of water flow rate L to air flow rate G: 0.5 to 20
(k9/k9) Based on this result, if the ratio of the amount of water (k9) contained in the discharged air to the amount of water (k9) supplied to each device is 0.1 (k9/k9) (
Calculate the relationship between the flow rate L (k9/hr) of the supply water and the superficial gas velocity Ug (m/sec) at a sufficiently stable operation with this amount of entrained droplets. As a result, results as shown in lines A and B in FIG. 2 were obtained.

Here, line A shows the results when using the gas-liquid contact device The results are shown when using the loaded gas-liquid contact device Y. Furthermore, line C shown in FIG. 2 shows the lower limit value Ugc of the superficial gas velocity when the contactor X is used, and line D shows the lower limit value Ugc of the superficial gas velocity when the contactor Y is used. It shows the lower limit value Ugc of speed.
Also, for reference, the amount of water supplied to the contact device X (
Gas superficial velocity Ug (m /sec), E(
4.8 h/sec) were obtained.

As is clear from the above results, Mr. Uchiyama et al.
It was found that the process can be carried out satisfactorily even at gas superficial velocities higher than Ugc, which was concluded in No. 131036 to be difficult to employ because the so-called overflow phenomenon would occur.

Furthermore, the inventors repeated many experiments in addition to the experiments described in this example, and found that the ratio of the amount of processing liquid contained in the discharged gas to be treated to the amount of processing liquid supplied was Although the amount of water that can be tolerated differs, it is possible to use a leakage shelf with an opening ratio of 0.3 to 0.6 and a flow rate L of the processing liquid of 1 to 11×1 pk9/. hr, at least 1 h/sec from U as defined above as gas superficial velocity Ug, preferably ah/sec from U number, more preferably 6 m/sec from U number.
It was confirmed that the selection should be made from the range of sec.

Also, the ratio L of the flow rate L of the processing liquid to the flow rate G of the gas to be processed
/G is when the flow rate L of the processing liquid is 1 pi to 6 x 1 pi k9/h.
In the case of r, it is at least 0.5 or more, preferably in the range of 1.0 to 6.0, and the flow rate L of the processing liquid is 6 × 1 to 11.
It has been found that in the case of ×1 and k9/·hr, the value should be selected from the range of at least 1.5, preferably from 2.0 to 20. Example 2 Sulfur dioxide (S02) of 1370 mm was collected from the lower part of a gas-liquid contact device with a column diameter of 560 mm, which was loaded with 4 stages of leakage shelves consisting of perforated plates with a hole diameter of 8.5 ribs and an opening ratio of 0.32. A boiler exhaust gas containing 408,000 hr/hr was introduced from the top of the equipment. Mhol/its calcium carbonate (CaC
03) was allowed to flow down to bring the boiler exhaust gas into contact with the absorption liquid in a countercurrent manner, and the sulfur dioxide concentration in the exhaust gas discharged from the contact device was measured.

When the desulfurization rate was determined from this result, it was found to be 90.5%. However, in this case, the superficial gas velocity Ug in the apparatus is 4.8 h/sec, and the ratio L/G of the flow rate L of the absorption liquid to the flow rate G of the treated exhaust gas is 5.7.
(kg/k9). Furthermore, when the total pressure loss in the four stages of the leakage fence was measured, it was found to be 15%.

In addition, almost no absorption liquid was found to be carried out of the apparatus along with the gas to be treated, and it was confirmed that stable operation could be maintained over a long period of time. Furthermore, for comparison, the overflow point for the above-mentioned closure ratio of 0.32, that is, the upper limit U number as the gas superficial velocity claimed by Mr. Uchiyama et al. When calculated based on the calculation formula, it is 1.65m
/sec. Therefore, in the gas-liquid contactor of this example, the gas superficial velocity was set to 1.6 h/sec, which is the range claimed by Mr. Uchiyama et al., and an experiment was conducted. was found to be 75%.

Example 3 An average particle size of 2 mm and a true density of 2 mm were collected from the bottom of a gas-liquid contactor with a column diameter of 50 mm, which was loaded with one stage of leakage shelf consisting of a perforated plate with a hole diameter of 8.5 mm and an aperture ratio of 0.34. 4/ Introducing a simulated gas containing earth dust at a concentration of 0.4 N, and flowing 61,000 k9/hr of water from the top of the device,
The simulated gas and water were brought into contact with each other in a countercurrent manner, and the dust concentration in the gas discharged from the device was measured.

When the dust removal rate was determined from this result, it was found to be 99%. However, the gas superficial velocity Ug in the device in this case is 4 m/sec, and the ratio L/G of the flow rate L of Tokamasha water to the flow rate G of the simulated gas is 3.7 (k
9/k9). Furthermore, the pressure drop in the leak shelf was measured and was found to be 35 days and 20 days. Furthermore, although the gas superficial velocity mentioned above is considerably higher than the upper limit value U number for the gas superficial velocity claimed by Mr. Uchiyama et al., almost no water is detected that is entrained in the simulated gas and taken out of the apparatus. I couldn't. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is for specifically explaining the constituent elements of the method of the present invention, and is a schematic diagram showing the relationship between the flow rate L of the processing liquid and the gas superficial velocity Ug.

In Fig. 1, area A is U9m and the number of U obtained by the approximate calculation formula of Japanese Patent Publication No. 51-31036 and L/G=
0.5, and regions B-1 and B-2 indicate the processing liquid flow rate of 1p to 6×1pk9 in the present invention.
/force・hr and 6×1 pi super ~ 11×1 pi k9/de・hr
FIG. FIG. 2 shows the results of measuring the amount of processing liquid entrained in the gas to be processed and taken out of the apparatus.
In Figure 2, lines A and B indicate that the ratio of water contained in the discharged air to the amount of water supplied is 0.1 (kg/k9).
), the flow rate L of the supply water (k9/〆・h
r) and gas superficial velocity Ug (m/sec). Line A uses a leak shelf with an opening ratio of 0.32, and line B uses a leak shelf with a Sekiguchi ratio of 0.52. This corresponds to when used. Lines C and D indicate the lower limit value Ugc of the gas superficial velocity Ug that can be adopted in the method of the present invention. corresponds to the case where a leaky shelf with a closing ratio of 0.52 is used.

Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. Processing liquid is supplied from the upper part of a gas-liquid contacting device consisting of a leakage shelf column with a diameter of 500 mm or more, which is loaded with at least one stage of leakage shelves having an opening ratio Fc of 0.3 to 0.6. The ratio L/G of the flow rate L (kg/m^2·hr) of the processing liquid to the flow rate G (kg/m^2·hr) of the gas to be processed is 0.5 or more, and the flow rate L of the processing liquid is is 10^4 to 6 x 10^4
kg/m^2・hr while supplying the gas to be treated from the lower part of the contacting device, the gas superficial velocity Ug in the device is 3.43L, which is a function of Ugm defined below. ^-^0^. ^0^8^0^7・Ugm(m
/sec) to 10 (m/sec), thereby bringing the gas to be treated and the treatment liquid into countercurrent gas-liquid contact. A wet removal method for specific components. a Using a leakage shelf made of a perforated plate, the density of the processing liquid ρl
Density of the gas to be treated ρg (kg/m^3)
/m^3) ratio ρg/ρl is 0.838×10^-^3
If above: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ b Use a leakage shelf made of a perforated plate, and calculate the density of the treatment liquid ρl
Density of the gas to be treated ρg (kg/m^3)
/m^3) ratio ρg/ρl is 0.838×10^-^3
If it is less than: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ c Use a leakage shelf consisting of a grid plate, and the density of the processing liquid ρl
Density of the gas to be treated ρg (kg/m^3)
/m^3) when the ratio ρg/ρl is 1.20×10^-^3 or more: Ugm=67.8Fc・((ρg)/(
ρl)×10^3)^-^0^. ^5^7^6・(L/
G) ^-^0^. ^2^3・√(g・l)d Using a leakage shelf made of a grid plate, the density of the processing liquid ρl (kg/m^
When the ratio ρg/ρl of the density ρg (kg/m^3) of the gas to be treated to 3) is less than 1.20×10^-^3: Ugm=76.7Fc((ρg)/(ρl)× 10^
3) ^-^1^. ^2^5^5・(L/G)^-^0^
．． ^2^3・√(g・l) (In each of the above formulas, l is the capillary constant √((2σ)/(ρl・g)), and g is the acceleration of gravity (m/sec^2). , σ is the surface tension (kg/sec^2) of the treatment liquid.)2 A leakage shelf with a column diameter of 500 mm or more loaded with at least one stage of leakage shelves having an open area ratio Fc of 0.3 to 0.6. The processing liquid is supplied from the upper part of the gas-liquid contact device consisting of a tower, and the ratio L/G of the flow rate L (kg/m^2.hr) of the processing liquid to the flow rate G (kg/m^2.hr) of the gas to be treated is L/G. 1.5 or more, and the flow rate L of the processing liquid is more than 6×10^4 to 11
×10^4kg/m^2・hr while supplying the gas to be treated from the lower part of the contacting device, the gas superficial velocity Ug in the device is a function of Ugm defined below. 750.9L^-^0^. ＾5＾7・Ugm
(m/sec) to 10 (m/sec) to bring the gas to be treated and the treatment liquid into countercurrent gas-liquid contact. Wet removal method for specific components contained. a Using a leakage shelf made of a perforated plate, the ratio of the density ρg (kg/m^3) of the liquid to be treated to the density ρg (kg/m^3) of the processing liquid ρg/ρl
If is 0.838×10^-^3 or more: ▲ Formula,
There are chemical formulas, tables, etc. ▼ b Using a leakage shelf made of a perforated plate, the density of the treatment liquid ρl
Density of the gas to be treated ρg (kg/m^3)
/m^3) ratio ρg/ρl is 0.838×10^-^3
If it is less than: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ c Use a leakage shelf consisting of a grid plate, and the density of the processing liquid ρl
Density of the gas to be treated ρg (kg/m^3)
/m^3) when the ratio ρg/ρl is 1.20×10^-^3 or more: Ugm=67.8Fc・((ρg)/(
ρl)×10^3)^-^0^. ^5^7^6・(L/
G) ^-^0^. ^2^3・√(g・l)d Using a leakage shelf made of a grid plate, the density of the processing liquid ρl (kg/m^
When the ratio ρg/ρl of the density ρg (kg/m^3) of the gas to be treated to 3) is less than 1.20×10^-^3: Ugm=76.7Fc・((ρg)/(ρl) ×10
^3)^-^1^. ^2^5^5・(L/G)^-^0
^． ^2^3・√(g・l) (In the above equation, l is the capillary constant √((2σ)/(ρl・g)), and g is the acceleration of gravity (m/sec＾2). σ is the surface tension of the treatment liquid (kg/sec^2).)