JPH04300627A - Method for preventing clogging of flue - Google Patents

Abstract

PURPOSE:To effectively prevent gypsum-like material from adhering to the inner wall of a flue by spraying the corner or branching parts of the inner flue wall with the waste water from a wet desulfurizing method. CONSTITUTION:The corner part A or branching part B of the inner wall of a flue 11 is sprayed with the waste water from a wet desulfurizing device 15 to effectively remove the gypsum-like material adhering to the inner wall of the flue 11. Therefore, there is neither clogging nor constriction of the flue caused by the adhering of gypsum-like material to the inner flue wall. Since the waste water from the wet desulfurizing device is partially used for the above-mentioned spray water, the water supply balance is not affected in the desulfurizing process. Therefore, the waste water from the desulfurizing process can be minimized and the desulfurizing efficiency of the above-mentioned wet desulfurizing device will not be worsened. Since the inner flue wall is not rubbed, scratched or subjected to other detrimental actions in the sulfurizing process and, therefore, there is no impairment thereto, the durability period (service life) of the flue is improved.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] This invention is directed to a flue that leads high-temperature gas containing sulfur oxides, etc. discharged from an absorption tower in a sulfuric acid factory to a device that performs a wet desulfurization process, and that has a humidity control section at the inlet. The present invention relates to a method for preventing blockage of a flue, which prevents gypsum from forming on a part of the inner wall of the flue.

0002

[Prior Art] Gas discharged from absorption towers in sulfuric acid plants usually still contains about 0.2 to 0.3% SO2 gas, so it is further sent to a wet desulfurization equipment for final wet desulfurization. It is discharged after completing the process.

[0003] As a flue for guiding the high-temperature sulfur-containing gas discharged from the absorption tower of the sulfuric acid factory to the wet desulfurization equipment, a structure consisting of a flue 1 and a humidity control section 2 as shown in FIG. 3 is generally used. It is true.

Conventionally, steel was mainly used as the material for the flue 1, but because it is heavy and easily corroded, it is now made of fiber reinforced plastic (FRP). However, since the above-mentioned FRP is sensitive to high temperatures, a humidity control section 2 is provided at the entrance of the flue 1, and in this humidity control section 2, the high temperature (8
By spraying cooling water onto the sulfur-containing gas (about 0 to 100℃)
After the gas temperature has been sufficiently lowered, it is sent into the flue 1.

[0005] As the cooling water used in the humidity control section 2, the waste water from the wet desulfurization device 4 is usually reused for the purpose of reducing the amount of sulfur-containing waste water treated.

The wet desulfurization method used in the wet desulfurization equipment 4 passes high-temperature exhaust gas containing, for example, sulfur oxides into an absorbent containing an absorbent such as aluminum oxide or slaked lime slurry. This method absorbs the sulfur oxides inside and then turns this absorbed material into gypsum to desulfurize it. Therefore, the wastewater from the wet desulfurization equipment 4 contains calcium ions (Ca2+) and calcium sulfate (Ca2+).
The above-mentioned cooling water, which is reused as it is, naturally also contains Ca2+ and CaSO4. Therefore, when cooling water is sprayed onto the high-temperature sulfur-containing gas in the humidity control section 2 at the entrance of the flue 1, CaSO4 originally contained in the cooling water and SO2 in the sulfur-containing gas are removed.
CaSO4 produced by the reaction between gas and Ca2+ in the cooling water
Gypsum deposits mainly composed of and adhere to the corner portions of the flue indicated by symbol B and the branch portions of the flue indicated by C in the figure.

[0007] If the above-mentioned castings are left untreated, they will gradually accumulate, and the area in the flue where the castings occur will gradually become narrower, making it difficult for exhaust gas to pass through due to the narrowing of the flue due to such castings. As a result, the exhaust gas processing capacity gradually decreases.

[0008] Therefore, various methods have been proposed for eliminating or suppressing the occurrence of the above-mentioned sticking in the flue.

First, as a first conventional example, JP-A-1-1
There is a method using a flue cleaning device 5 as shown in FIG. 4, which is disclosed in Japanese Patent No. 39913. This device uses a brush 7 attached to the tip of a rotary arm 6 to rotate the brush 7 along the inner circumferential wall of the flue while scraping off ash dust (casting) deposited on the inner surface of the flue. This is a device that moves to clean the inside of the flue.

As a second conventional example, a flue 1 shown in FIG.
Water is sprayed on corner parts A and branch parts B where molding on the inner surface tends to adhere, and the water pressure blows off the moldings and washes them away.
This method prevents the build-up of moldings on the pipes and thereby prevents the flue 1 from clogging.

[0011]

[Problems to be Solved by the Invention] However, in the method of scraping off the casting using a machine as in the first conventional example, when scraping off the casting with the brush 7, the inside of the flue is damaged. There is a problem in that there is a risk of damage, and this is even more likely with the FRP flue currently in use. In addition, in the cleaning device of this example, which is originally designed to clean the inside of a straight flue that is not curved or branched, the cleaning device is designed to clean the inside of a straight flue that is not curved or branched. It is not suitable for removing molding that has adhered to areas such as the following.

In addition, in the second conventional example, the water that is sprayed onto the corner A and the branch where the molding has adhered on the inner surface of the flue is newly introduced from the outside into the system for the series of exhaust gas desulfurization steps shown in FIG. Because of this water, the water balance in this desulfurization process is disrupted, and for example, the circulating water in the wet desulfurization device 4 is diluted and the desulfurization efficiency deteriorates, or the amount of sulfur-containing wastewater increases rapidly. New problems have arisen, such as the need to treat large amounts of wastewater.

The present invention was made in view of the above circumstances, and effectively prevents gypsum from forming in areas where gypsum is likely to form, such as corners and branching areas, and prevents damage to the inner wall of the flue or during the desulfurization process. The purpose of the present invention is to provide a method for preventing blockage of a flue without causing harmful effects such as disrupting the water balance.

[0014]

[Means for Solving the Problems] The problem is to cool the waste water from the device that performs the wet desulfurization process on the exhaust gas at the entrance of the flue that leads the high temperature sulfur-containing exhaust gas to the device that performs the wet desulfurization process. A method for preventing blockage of a flue having a humidity control section that sprays water as water to lower the temperature of the exhaust gas, the method comprising: spraying wastewater from the wet desulfurization process device onto a desired part of the inner wall of the flue; This problem can be solved by removing the plaster build-up that adheres to the inner wall of the flue.

The present invention will now be explained in detail by way of examples. FIG. 1 is a schematic diagram showing an example of an apparatus suitably used for carrying out the method for preventing blockage of a flue according to the present invention.
is a flue, 12 is a humidity control section, 13 is a nozzle, 14 is an absorption tower,
15 is a wet desulfurization device.

The flue 11 is for guiding the high temperature sulfur-containing exhaust gas from the absorption tower 14 to the wet desulfurization device 15. This flue 11 has many curved parts as shown by the symbol A in the figure and branch parts as shown by B depending on the positional relationship between the absorption tower 14 and the wet desulfurization device 15.

Nozzles 13 are provided in all parts of the curved portion A and the branched portion B, and a pump 16 is provided near these plurality of nozzles 13. Furthermore, the pump 16 performs wet desulfurization via a water channel 17. is in contact with device 15.

A humidity control section 12 is provided at the gas inlet of the flue 11, and the high temperature sulfur-containing gas from the absorption tower 14 is first treated in the humidity control section 12 before being sent into the flue 11. , it is designed to be cooled by cooling water sprayed from the nozzle 18.

In addition, the cooling water sprayed at this time is pumped up from a part of the waste water of the wet desulfurization device 15 by the pump 19, and is sent to the humidity control section 12 at a flow rate of about 1700 to 1900 Nm3/min. By spraying the cooling water at a rate of about 30 liters/second to the sulfur-containing gas (containing 0.2 to 0.3% SO2 gas) at ℃, the gas temperature is cooled to about 30℃. There is.

The desulfurization method used in the wet desulfurization apparatus 15 may be any wet desulfurization method, and for example, a method as shown in FIG. 2 is preferable.

In the method shown in FIG. 2, first, Al2O3 and air are fed into SO2 gas and reacted to form Al2(
SO4)3 and further add Ca to this Al2(SO4)3.
By applying CO3 slurry, SO2 gas is recovered as CaSO4 (gypsum), and the Al produced at the same time is
2O3 is a reuse method. In addition, the wastewater discharged from the desulfurization process using the desulfurization method described above contains CaC.
Ca ions derived from O3 slurry and fine unrecovered Ca
Contains SO4 (gypsum), etc. Therefore, as described above, since the waste water from the wet desulfurization apparatus is used as cooling water in the humidity control section, gypsum cast deposits are likely to accumulate particularly at portions such as the curved portion A and the branched portion B.

[0022] The method for preventing blockage of a flue according to the present invention includes, for example,
When using the flue with the above configuration, the curved part A and the branch part B are prone to gypsum casting and accumulation due to Ca ions in the cooling water used in the humidity control section, unrecovered CaSO4 (gypsum), etc. On the other hand, water is sprayed using anti-casting means consisting of a nozzle 13 and a pump 16 provided near these parts, and a part of the drainage water from the wet desulfurization equipment is reused as the water used for spraying. This is a structured method.

[0023]

[Example] The above-mentioned flue 11 was actually manufactured, exhaust gas from an absorption tower of a sulfuric acid factory was actually sent into the flue 11, and at the same time, the method for preventing casting in the flue of the present invention was continuously applied.
It was conducted for a month.

[0024] The flue 11 is made of FRP and has a wall thickness of 8
A cylindrical type with an outer diameter of 1900 mm was used. In addition, the dimensions of the parts indicated by symbols C and D in the figure are 22 m, respectively.
It was set to 80m.

After using the flue 11 for one month, we inspected the inside of the flue and found that there was no molding at all in the straight part of the flue 11, and there was no molding in the curved part A or the branched part B. It was hardly seen.

[0026]

Effects of the Invention In the method for preventing blockage of a flue according to the present invention, waste water from a wet desulfurization process is sprayed onto a desired part of the flue inner wall to prevent plaster-like particles adhering to the flue inner wall. Since this is a method for removing molding, it is possible to effectively prevent plaster molding from adhering to various parts such as corners and branching parts. Therefore, no blockage or narrowing of the flue due to plaster adhesion to the inner wall of the flue occurs.

[0027] In addition, in this method, a part of the wastewater from the equipment that performs the wet desulfurization process is reused as the water to be sprayed on the plaster cast, so the water balance in the desulfurization process is improved. It won't break down. Therefore, the waste water from the desulfurization process can be minimized, and the desulfurization efficiency of the wet desulfurization apparatus described above will not be deteriorated.

[0028] In addition, in this method, the inner wall of the flue is rubbed.
Since there is no scratching or other operations, there is no damage to the inner wall of the flue. Therefore, the durability period (usage life) of the flue is improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a device suitably used to carry out the method for preventing blockage of a flue according to the present invention.

FIG. 2 is a schematic diagram showing an example of a wet desulfurization system used in the wet desulfurization apparatus shown by reference numeral 15 in FIG.

FIG. 3 is a conventional flue for introducing sulfur-containing exhaust gas discharged from an absorption tower or the like of a sulfuric acid factory into a device that performs a wet desulfurization process.

FIG. 4 is a diagram showing a first conventional flue cleaning device.

[Explanation of symbols]

11 Flue 12 Humidity control section 13 Nozzle 15 Wet desulfurization equipment

Claims (1)

[Claims] Claim 1: The temperature of the exhaust gas is lowered by spraying waste water from the apparatus for performing the wet desulfurization process onto the exhaust gas as cooling water at the entrance of the flue that leads the high temperature sulfur-containing exhaust gas to the apparatus for performing the wet desulfurization process. A method for preventing clogging of a flue having a humidity control section that lowers humidity, the method comprising: spraying waste water from the wet desulfurization process device onto a desired part of the inner wall of the flue, and removing gypsum that adheres to the inner wall of the flue. A method for preventing blockage of a flue, characterized by removing cast-on.