WO2014162992A1 - 蒸気発生設備のスケール除去方法 - Google Patents
蒸気発生設備のスケール除去方法 Download PDFInfo
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- WO2014162992A1 WO2014162992A1 PCT/JP2014/059039 JP2014059039W WO2014162992A1 WO 2014162992 A1 WO2014162992 A1 WO 2014162992A1 JP 2014059039 W JP2014059039 W JP 2014059039W WO 2014162992 A1 WO2014162992 A1 WO 2014162992A1
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- boiler
- average molecular
- molecular weight
- weight average
- polyacrylic acid
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 90
- 229920002125 Sokalan® Polymers 0.000 claims abstract description 66
- 239000004584 polyacrylic acid Substances 0.000 claims abstract description 65
- 150000003839 salts Chemical class 0.000 claims abstract description 28
- 238000004364 calculation method Methods 0.000 claims abstract description 9
- 238000005260 corrosion Methods 0.000 abstract description 8
- 230000007797 corrosion Effects 0.000 abstract description 8
- 238000012360 testing method Methods 0.000 description 33
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 24
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 18
- 238000012546 transfer Methods 0.000 description 16
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 14
- 229910052742 iron Inorganic materials 0.000 description 12
- 229920002845 Poly(methacrylic acid) Polymers 0.000 description 10
- 239000003795 chemical substances by application Substances 0.000 description 10
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000000377 silicon dioxide Substances 0.000 description 9
- 239000011575 calcium Substances 0.000 description 7
- 239000002738 chelating agent Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- 229910000029 sodium carbonate Inorganic materials 0.000 description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 5
- 239000003513 alkali Substances 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910052749 magnesium Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000008400 supply water Substances 0.000 description 5
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910000288 alkali metal carbonate Inorganic materials 0.000 description 4
- 150000008041 alkali metal carbonates Chemical class 0.000 description 4
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 229910000318 alkali metal phosphate Inorganic materials 0.000 description 3
- 150000001412 amines Chemical class 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 229940079593 drug Drugs 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000003472 neutralizing effect Effects 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- YNAVUWVOSKDBBP-UHFFFAOYSA-N Morpholine Chemical compound C1COCCN1 YNAVUWVOSKDBBP-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- PAFZNILMFXTMIY-UHFFFAOYSA-N cyclohexylamine Chemical compound NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 description 2
- 235000014413 iron hydroxide Nutrition 0.000 description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- 229920001444 polymaleic acid Polymers 0.000 description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000002455 scale inhibitor Substances 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- HXKKHQJGJAFBHI-UHFFFAOYSA-N 1-aminopropan-2-ol Chemical compound CC(O)CN HXKKHQJGJAFBHI-UHFFFAOYSA-N 0.000 description 1
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 1
- 229940058020 2-amino-2-methyl-1-propanol Drugs 0.000 description 1
- BFSVOASYOCHEOV-UHFFFAOYSA-N 2-diethylaminoethanol Chemical compound CCN(CC)CCO BFSVOASYOCHEOV-UHFFFAOYSA-N 0.000 description 1
- FAXDZWQIWUSWJH-UHFFFAOYSA-N 3-methoxypropan-1-amine Chemical compound COCCCN FAXDZWQIWUSWJH-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 1
- 229940123973 Oxygen scavenger Drugs 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical class OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- CBTVGIZVANVGBH-UHFFFAOYSA-N aminomethyl propanol Chemical compound CC(C)(N)CO CBTVGIZVANVGBH-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- 229910000397 disodium phosphate Inorganic materials 0.000 description 1
- 235000019800 disodium phosphate Nutrition 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- RECVMTHOQWMYFX-UHFFFAOYSA-N oxygen(1+) dihydride Chemical group [OH2+] RECVMTHOQWMYFX-UHFFFAOYSA-N 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 235000019832 sodium triphosphate Nutrition 0.000 description 1
- -1 trisodium acid Chemical class 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 1
- 235000019801 trisodium phosphate Nutrition 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
- C11D3/16—Organic compounds
- C11D3/37—Polymers
- C11D3/3746—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C11D3/3757—(Co)polymerised carboxylic acids, -anhydrides, -esters in solid and liquid compositions
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
- C23F11/173—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F14/00—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes
- C23F14/02—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes by chemical means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
- F22B37/48—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers
- F22B37/52—Washing-out devices
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2307/00—Location of water treatment or water treatment device
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
- C11D2111/10—Objects to be cleaned
- C11D2111/14—Hard surfaces
- C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines
Definitions
- the present invention relates to a scale removal method for steam generating equipment.
- the scale inhibitor is used to prevent the scaling of hardness components brought into the aqueous system, for example, a phosphate such as trisodium phosphate or sodium tripolyphosphate, or a polymer such as sodium polyacrylate. in use.
- Patent Document 1 describes a scale removal method by chemical cleaning using a chelating agent such as high concentration ethylenediaminetetraacetic acid (EDTA) or an organic acid such as sulfamic acid.
- EDTA ethylenediaminetetraacetic acid
- Patent Document 1 has a problem that productivity is impaired because the boiler is stopped once, and cleaning costs are separately generated.
- Patent Document 2 a specific chelating agent such as EDTA, nitrilotriacetic acid (NTA) and diethylenetriamine and a specific dispersing agent such as polymaleic acid are added to a boiler can, and the scale is adjusted while operating the boiler. A method of removal is described.
- the chelating agent used in the scale removal method of Patent Document 2 has a problem that the chelating agent acts on iron, which is the base material of the boiler, to cause corrosion.
- the present invention has been made under such circumstances, and provides a scale removal method for a steam generating facility that can remove scale adhered in a boiler can without corroding the boiler during boiler operation. With the goal.
- the present inventors have been able to remove the adhered scale by polyacrylic acid or a salt thereof conventionally used to prevent the scale from adhering to the boiler can. I found out. As a result of further research, the present inventors have found a use condition of polyacrylic acid or a salt thereof capable of dramatically increasing the scale removal efficiency, and have solved the above problems.
- the present invention provides the following [1] to [3].
- [1] In the steam generation facility, during the operation of the boiler, the pH of the boiler water is adjusted to 11.3 or more, and the reference weight average derived from the following formula (1) according to the pH value of the boiler water
- Reference weight average molecular weight -8462 x (pH value-11.3) + 61538 (1)
- the pH of the boiler water is adjusted to 11.3 or more, and the reference weight average molecular weight calculated by the following method is determined according to the pH value of the boiler water.
- the weight average molecular weight (Mw max ) of polyacrylic acid that maximizes the scale removal rate is measured at at least three pH values of pH 11.3 or higher.
- the scale adhered to the boiler can be removed during boiler operation without using a chelating agent.
- FIG. 3 is a graph showing the relationship between the weight average molecular weight of polyacrylic acid and the scale removal rate in the pH range of 11.1 to 12.0.
- FIG. 3 is a graph showing the relationship between pH and the weight average molecular weight of polyacrylic acid that is optimal for descaling in the pH range of 11.1 to 12.0.
- FIG. 5 is a diagram of the relationship between pH and the weight average molecular weight of polyacrylic acid that is optimal for descaling in the region of pH 11.3-12.0 by the least square method.
- the scale removal method of the steam generating facility adjusts the pH of the boiler water to 11.3 or more during operation of the boiler in the steam generating facility, and according to the pH value of the boiler water, the following calculation formula: By adding polyacrylic acid or a salt thereof having a weight average molecular weight of 0.50 to 2.00 times the standard weight average molecular weight derived from (1), the scale attached to the boiler can is removed. .
- Reference weight average molecular weight -8462 x (pH value-11.3) + 61538 (1)
- FIG. 1 is a diagram showing an embodiment of a steam generation facility for carrying out the present invention.
- 1 shows a condensate tank 1, a condensate line 11, a make-up water tank 2, a make-up water line 21, a feed water tank 3, a feed water line 31, a polyacrylic acid or salt addition means 4, an alkali addition means 5, and steam generation.
- a circulation type steam generation facility 7 having a section (boiler can) 6 and a drain recovery line 71 is shown.
- FIG. 1 shows a circulation type steam generation facility, the scale removal method of the present invention can also be applied to a once-through type steam generation facility.
- FIG. 2 is a graph showing the relationship between the weight average molecular weight of polyacrylic acid and the scale removal rate in the pH range of 11.1 to 12.0. As shown in FIG. 2, it can be seen that the descaling rate increases as the pH increases, and in particular, there is a dramatic difference between pH 11.1 and 11.3. FIG. 2 is based on the results of Test Example 1 described later.
- produced in the boiler can be made favorable by making pH of boiler water 11.3 or more.
- the scale adhering in the boiler can rarely adheres to a single component, and many are a mixture of multiple components such as calcium, magnesium and silica.
- the pH is increased to 11.3 or more, the solubility of silica in the generated scale mixture is increased, and at the same time, it is considered that the scale mixture derived from calcium or magnesium is easily removed.
- the pH of the boiler water is preferably 11.5 or more from the viewpoint of the scale removal rate, and preferably 12.0 or less from the viewpoint of preventing corrosion in the boiler can or the steam generating equipment system.
- Examples of the alkali agent include alkali metal hydroxides, alkali metal carbonates, alkali metal phosphates, and neutralizing amines.
- Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, and lithium hydroxide.
- Examples of the alkali metal carbonate include sodium carbonate and potassium carbonate.
- Examples of the alkali metal phosphate include phosphorus. Examples thereof include trisodium acid and sodium hydrogen phosphate.
- Examples of the neutralizing amine include monoethanolamine, cyclohexylamine, morpholine, diethylethanolamine, monoisopropanolamine, 3-methoxypropylamine, 2-amino-2-methyl-1-propanol and the like.
- alkali agent an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal phosphate are preferable, and sodium hydroxide, potassium hydroxide, sodium carbonate, etc. are more preferable from an economical viewpoint.
- the said alkali agent can be used individually by 1 type or in combination of 2 or more types.
- the alkaline agent is preferably added to makeup water or water supply.
- the steam generation facility when it is a circulation type, it may be added to the condensate.
- raw water treated with a reverse osmosis membrane raw water softened, raw water ion exchange treated, or the like can be used.
- polyacrylic acid or its salt is added, adjusting the pH of boiler water to 11.3 or more.
- the polyacrylic acid is not particularly limited, and a polyacrylic acid that satisfies the condition of the weight average molecular weight described later can be used.
- the polyacrylic acid salt include the sodium salt and potassium salt of the polyacrylic acid.
- the polyacrylic acid salt can be obtained by adding an alkali metal hydroxide such as sodium hydroxide and potassium hydroxide, an alkali metal carbonate such as sodium carbonate and potassium carbonate, and the like together with polyacrylic acid.
- polyacrylic acid or a salt thereof having a weight average molecular weight of 0.50 to 2.00 times the standard weight average molecular weight derived from the following calculation formula (1) according to the pH value of boiler water Is used.
- Reference weight average molecular weight -8462 x (pH value-11.3) + 61538 (1)
- the weight average molecular weight of the polyacrylic acid is preferably 0.70 to 1.70 times, more preferably 0.80 to 1.60 times the reference weight average molecular weight derived from the above formula (1). Is more preferably 0.90 to 1.40 times.
- the weight average molecular weight of the polyacrylic acid serving as the base of the polyacrylic acid salt only needs to satisfy the above conditions.
- FIG. 3 is a graph showing the relationship between pH and the weight average molecular weight of polyacrylic acid that is optimal for descaling in the pH range of 11.1 to 12.0.
- the optimum weight average molecular weight of polyacrylic acid decreases as the pH increases, and a substantially linear relationship is observed between pH 11.3 and pH 12.0.
- the optimum weight average molecular weight of polyacrylic acid at each pH as a base of FIG. 3 is read from FIG.
- the above formula (1) can be calculated by performing the least squares method in the section between pH 11.3 and pH 12.0, which is a substantially linear relationship, and the reference weight average molecular weight at each pH is obtained. (See FIG. 4).
- FIG. 4 See FIG. 4).
- a calculation formula for obtaining the reference weight average molecular weight is calculated from the three-point least-squares method of pH 11.3, 11.5, 12.0, but at least three of pH 11.3 or higher are calculated.
- the weight average molecular weight (Mw max ) of polyacrylic acid that maximizes the scale removal rate is measured, and the relationship between pH and Mw max is determined by the least square method with pH as x axis and Mw max as y axis.
- the weight average molecular weight at each pH obtained from the relational expression may be used as the reference weight average molecular weight.
- a scale removal rate can be made favorable by adding the polyacrylic acid or its salt which satisfy
- the amount of polyacrylic acid or its salt added is preferably such that the concentration in the boiler water is 10 to 500 mg / L. By setting it to 10 mg / L or more, the scale removal effect can be easily exerted, and by setting it to 500 mg / L or less, it is possible to improve cost effectiveness while preventing the complexity of wastewater treatment due to an increase in COD.
- the addition amount of polyacrylic acid or a salt thereof is more preferably 20 to 400 mg / L, more preferably 30 to 300 mg / L, more preferably 50 to 250 mg / L in the boiler water. It is even more preferable.
- polyacrylic acid or a salt thereof it is preferable to add polyacrylic acid or a salt thereof to make-up water or water supply.
- the steam generation facility when it is a circulation type, it may be added to the condensate.
- a pH measuring means on the upstream side and / or downstream side of the boiler can and associating the means with a means for adding polyacrylic acid or a salt thereof, polyacrylic acid having an appropriate weight average molecular weight is obtained. It is preferable to adopt a configuration in which it is automatically selected and added.
- ⁇ Optional components> various additive components such as oxygen scavengers, anticorrosives, and scale prevention are provided at any point in the system of the steam generation facility as necessary.
- An agent or the like can be used.
- the scale inhibitor include water-soluble polymer compounds such as various phosphates, polyacrylic acid that does not satisfy the above-described conditions (low weight average molecular weight), polymethacrylic acid, polymaleic acid, and sodium salts thereof. Phosphonates, chelating agents and the like.
- polymethacrylic acid is used in combination with polyacrylic acid or a salt thereof satisfying the above conditions, so that when the iron concentration in the boiler feed water exceeds 0.3 mg / L (for example, 0.3 to This is preferable in that the scale removal efficiency (in the case of a high concentration of 5.0 mg / L) can be dramatically increased.
- concentration of polymethacrylic acid in the boiler water is preferably 1 to 1,000 mg / L, and more preferably 10 to 500 mg / L.
- the polymethacrylic acid is added in the boiler water so that the mass ratio of polyacrylic acid (salt): polymethacrylic acid (salt) is 1: 100 to 100: 1, particularly 1:50 to 50: 1. Is preferred.
- the polymethacrylic acid preferably has a weight average molecular weight of 1,000 to 100,000 or less, and more preferably 5,000 to 60,000.
- polymethacrylic acid has a weight average molecular weight of less than 1,000, a sufficient iron scale prevention effect may not be obtained, and when the polymethacrylic acid has a weight average molecular weight of more than 100,000, the effect decreases.
- Test Example 1 Under the following conditions, the influence of pH and the weight average molecular weight of polyacrylic acid on the scale removal rate was examined.
- Test equipment Stainless steel test boiler Synthetic water A: Concentration in feed water Ca hardness: 10 mg CaCO 3 / L, Mg hardness: 5 mg CaCO 3 / L, silica 15 mg / L, sodium carbonate 25 mg / L
- Synthetic water B 15 mg / L of silica as the concentration in the feed water, 20 mg / L of polyacrylic acid having a weight average molecular weight described in Table 1 (200 mg / L as the concentration in the boiler can), and the boiler water pH described in Table 1 So that sodium carbonate is added to the water supply water temperature: 40 ° C
- Operating pressure 2.0 MPa Water supply amount: 9L / h Concentration magnification: 10 times
- Measurement of scale removal rate Weigh and record a heat transfer tube (made of steel, surface area 200 cm 2 ⁇ 3) before the test.
- Synthetic water equivalent to 10-fold concentration in boiler can (equivalent to 10-fold concentration of synthetic water A) is prepared and fed into a stainless steel test boiler (retained water volume 5 L), and pressure of 2.0 MPa while supplying synthetic water A The mixture was operated for 21 hours so that the evaporation amount was 8.2 L / h, the blow amount was 0.8 L / h, and the concentration rate was 10 times.
- a heat transfer tube (made of iron, surface area of 200 cm 2 ⁇ 3) with a scale attached after operation was taken out and weighed, and the amount of scale attached was calculated.
- FIG. 2 shows the relationship between the weight average molecular weight of polyacrylic acid and the scale removal rate for each pH.
- FIG. 3 is a graph showing the optimum weight average molecular weight of polyacrylic acid at each pH.
- FIG. 3 shows that a substantially linear relationship is recognized between pH 11.3 and pH 12.0.
- the intercept is 61,538 and the slope is ⁇ 8,462.
- Test apparatus Stainless steel test boiler Synthetic water C: Concentration in feed water Ca hardness: 20 mg CaCO 3 / L, Mg hardness: 10 mg CaCO 3 / L, silica 15 mg / L, sodium carbonate 35 mg / L Synthetic water D: Added to the feed water so that the concentration in the feed water is 15 mg / L of silica and 20 mg / L of sodium carbonate, and the chemicals listed in Table 2 are added to the feed water so that the concentration in the boiler can is listed in Table 2.
- a heat transfer tube (made of iron, surface area of 200 cm 2 ⁇ 3) with a scale attached after operation was taken out and weighed, and the amount of scale attached was calculated. Thereafter, the heat transfer tube was inserted again, and synthetic water corresponding to 10-fold concentration of synthetic water D was prepared and charged into the can, and the scale removal process was performed with synthetic water D for 6 days under the same conditions. . Similarly, the heat transfer tube was weighed after the operation, and the scale removal rate was calculated from the amount of scale attached before and after the scale removal step. The results are shown in Table 2.
- test examples 2-9 to 2-22 satisfy the conditions of the weight average molecular weight of the polyacrylic acid of the present invention, and scale removal is performed as compared with other test examples having the same polyacrylic acid concentration. It can be seen that the rate is good.
- Test Example 3 Under the same conditions as in Test Example 2, when removing the scale using synthetic water D (however, the chemical type, molecular weight, and boiler canister concentration are the same as those shown in Table 3), the steel material in the boiler can is removed.
- a test piece (SGP, 15 ⁇ 50 ⁇ 10 mm, # 400 polishing) made by the method was installed and subjected to derusting after the test, and the corrosion rate was determined by the following calculation formula (2).
- Corrosion rate (mdd) corrosion loss of test piece (mg) / surface area of test piece (dm 2 ) ⁇ test period (day)
- Test Example 4 (All scale removal rate) Except for using synthetic water F as a feed water to which iron chloride and iron hydroxide are added at a mass ratio of 1: 1 so that the iron concentration is 1.5 mg / L with respect to synthetic water C, Under the same conditions as in Test Example 2, a test boiler having a heat transfer tube (made of steel, surface area 200 cm 2 ⁇ 3) was operated for 21 hours. After operation, one of the three heat transfer tubes was removed and replaced with a polished heat transfer tube. Moreover, the taken-out heat transfer tube was weighed and the amount of scale adhesion was calculated.
- iron chloride and iron hydroxide are added at a mass ratio of 1: 1 with respect to the synthetic water D so that the iron concentration is 1.5 mg / L, and the drugs are listed in Table 4.
- the scale removal process was performed by operating the test boiler for 6 days under the same conditions as in Test Example 2 except that synthetic water G obtained by changing to chemicals, molecular weight, and boiler internal concentration was used as feed water. After the additional operation, the heat transfer tubes that were not replaced after the previous operation were weighed, and the total scale removal rate was calculated from the amount of scale attached before and after the scale removal step. The results are shown in Table 4.
- the polyacrylic acids in Test Examples 4-2 to 4-11 satisfy the weight average molecular weight conditions of the present invention. These test examples show a good scale removal rate. Among them, Test Examples 4-8 to 4-11 show a markedly excellent scale removal rate. From this result, when iron is contained in boiler feed water at a relatively high concentration, the total scale removal rate is dramatically improved by combining polyacrylic acid with polymethacrylic acid rather than single treatment with polyacrylic acid. It can be confirmed that it can be improved. This means that with polyacrylic acid alone, the dispersion effect of the iron scale cannot be optimized, and the iron scale further adheres on the hardness scale, and as a result, the removal effect of the hardness scale is reduced. Presumed. On the other hand, when polymethacrylic acid is combined with polyacrylic acid, it is understood that the iron scale is prevented from adhering to the hardness scale, and the hardness scale removing effect by polyacrylic acid is sufficiently exhibited.
- Condensate tank 11 Condensate line 2: Supply water tank 21: Supply water line 3: Supply water tank 31: Supply water line 4: Polyacrylic acid or its salt 5: Alkaline agent 6: Steam generation part (boiler can) 61 : Drain recovery line 7: Steam generation facility
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Abstract
Description
特に、ボイラ水系では、ボイラ缶内に持ち込まれたカルシウム、マグネシウム、シリカ及び鉄などのスケール成分は、熱負荷の高い伝熱面でスケール化して付着するため、鋼材の過熱による膨張、湾曲、破裂や熱効率の低下を引き起こす原因となる。
また、伝熱面へのスケールの付着は、伝熱阻害を引き起こし、エネルギーロスが生じるため、燃料費の増加にもつながる。このため、ボイラ水系などでは、スケールの付着を防止するために、原水中の硬度成分であるカルシウムやマグネシウムを軟水器によって取り除き、軟水化したものを給水としている。
ここで、スケール防止剤とは、水系システムに持ち込まれた硬度成分のスケール化を防止するものであり、例えばリン酸三ナトリウムやトリポリリン酸ナトリウムなどのリン酸塩、ポリアクリル酸ナトリウムなどのポリマーが使用されている。
しかし、特許文献1のスケール除去方法では、ボイラを一度停止するため生産性が損なわれることと、洗浄コストが別途発生するといった問題がある。
[1]蒸気発生設備において、ボイラの稼働中に、ボイラ水のpHを11.3以上に調整し、かつボイラ水のpHの値に応じて、下記計算式(1)から導かれる基準重量平均分子量の0.50~2.00倍の重量平均分子量を有するポリアクリル酸又はその塩を添加することにより、ボイラ缶内に付着したスケールを除去する、蒸気発生設備のスケール除去方法。
基準重量平均分子量 = -8462×(pHの値-11.3)+61538 ・・・(1)
[2]蒸気発生設備において、ボイラの稼働中に、ボイラ水のpHを11.3以上に調整し、かつボイラ水のpHの値に応じて、下記の手法により算出される基準重量平均分子量の0.50~2.00倍の重量平均分子量を有するポリアクリル酸又はその塩を添加することにより、ボイラ缶内に付着したスケールを除去する、蒸気発生設備のスケール除去方法。
[基準重量平均分子量の算出方法]
(1)pH11.3以上の少なくとも3つのpH値において、スケール除去率が最大となるポリアクリル酸の重量平均分子量(Mwmax)を測定する。
(2)pHをx軸、Mwmaxをy軸として、最小二乗法によりpHとMwmaxとの関係式を求め、該関係式から得られる各pHでの重量平均分子量を、基準重量平均分子量とする。
[3]前記ポリアクリル酸又はその塩を、前記ボイラ水中での濃度が10~500mg/Lとなるように添加する、上記[1]または[2]に記載の蒸気発生設備のスケール除去方法。
基準重量平均分子量 = -8462×(pHの値-11.3)+61538 ・・・(1)
図1は、復水タンク1、復水ライン11、補給水タンク2、補給水ライン21、給水タンク3、給水ライン31、ポリアクリル酸又はその塩の添加手段4、アルカリ添加手段5、蒸気発生部(ボイラ缶)6及びドレン回収ライン71を有する、循環式の蒸気発生設備7を示している。
なお、図1は循環式の蒸気発生設備を示しているが、本発明のスケール除去方法は、貫流式の蒸気発生設備にも適用することができる。
本発明の蒸気発生設備のスケール除去方法では、まず、ボイラ水のpHを11.3以上に調整する。
図2は、pH11.1~12.0の領域における、ポリアクリル酸の重量平均分子量とスケール除去率との関係を示す図である。図2に示すように、pHが高くなるにつれてスケール除去率が高くなっており、特に、pH11.1と11.3との間で劇的な差があることが認められる。なお、図2は、後述する試験例1の結果に基づくものである。
このように、本発明では、ボイラ水のpHを11.3以上とすることにより、ボイラ缶内に発生したスケールの除去率を良好にすることができる。ボイラ缶内に付着しているスケールは単一成分が付着することは少なく、多くはカルシウム、マグネシウム及びシリカ等の多成分の混合物である。ここでpHが11.3以上に上昇すると発生したスケール混合物中のシリカの溶解性が上がるため、同時にカルシウムやマグネシウム由来のスケール混合物が除去されやすくなると考えられる。
ボイラ水のpHは、スケール除去率の観点から11.5以上とすることが好ましく、ボイラ缶内や蒸気発生設備系内の腐食防止の観点から12.0以下とすることが好ましい。
アルカリ金属水酸化物としては、水酸化ナトリウム、水酸化カリウム、水酸化リチウム等が挙げられ、アルカリ金属炭酸塩としては、炭酸ナトリウム、炭酸カリウム等が挙げられ、アルカリ金属リン酸塩としては、リン酸三ナトリウム、リン酸水素ナトリウム等が挙げられる。
また、中和性アミンとしては、モノエタノールアミン、シクロへキシルアミン、モルホリン、ジエチルエタノールアミン、モノイソプロパノールアミン、3-メトキシプロピルアミン、2-アミノ-2-メチル-1-プロパノール等が挙げられる。
アルカリ剤の中でも中和性アミンは、蒸気復水系へ移行するため、ボイラ水のpHを11.3以上に調整するには高濃度添加しなければならず、またそのような濃度添加をすると蒸気や復水に臭気が生じたり、蒸気復水系のpHが上昇しすぎてしまい系内に銅系材質があると腐食を引き起こす可能性がある。このため、アルカリ剤としては、アルカリ金属水酸化物、アルカリ金属炭酸塩、アルカリ金属リン酸塩が好ましく、経済性の観点から、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム等がより好ましい。
上記アルカリ剤は、一種単独で又は二種以上を組み合わせて用いることができる。
なお、適量のアルカリ剤を供給するために、ボイラ缶の上流側及び/又は下流側に、pH測定手段を有することが好ましい。
本発明では、ボイラ水のpHを11.3以上に調整しつつ、ポリアクリル酸又はその塩の添加を行う。
ポリアクリル酸は特に限定されず、後述する重量平均分子量の条件を満たすものを用いることが可能である。ポリアクリル酸塩は、前記ポリアクリル酸のナトリウム塩、カリウム塩等が挙げられる。ポリアクリル酸塩は、ポリアクリル酸とともに、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物、炭酸ナトリウム、炭酸カリウム等のアルカリ金属炭酸塩等を添加することにより得ることができる。
基準重量平均分子量 = -8462×(pHの値-11.3)+61538 ・・・(1)
また、ポリアクリル酸の重量平均分子量は、上記計算式(1)から導かれる基準重量平均分子量の0.70~1.70倍であることが好ましく、0.80~1.60倍であることがより好ましく、0.90~1.40倍であることがさらに好ましい。
なお、ポリアクリル酸の塩の場合、ポリアクリル酸塩のベースとなるポリアクリル酸の重量平均分子量が上記条件を満たしていればよい。
そして、略直線的関係であるpH11.3と~pH12.0の区間の最小二乗法を行うことにより、上記計算式(1)を算出することができ、各pHでの基準重量平均分子量を得ることができる(図4参照)。
なお、図4では、pH11.3、11.5、12.0の3点の最小二乗法から基準重量平均分子量を得るための計算式を算出しているが、pH11.3以上の少なくとも3つのpH値において、スケール除去率が最大となるポリアクリル酸の重量平均分子量(Mwmax)を測定し、pHをx軸、Mwmaxをy軸として、最小二乗法によりpHとMwmaxとの関係式を求め、該関係式から得られる各pHでの重量平均分子量を、基準重量平均分子量としてもよい。
また、ポリアクリル酸又はその塩の添加量は、前記ボイラ水中での濃度が20~400mg/Lとすることがより好ましく、30~300mg/Lとすることがさらに好ましく50~250mg/Lとすることがよりさらに好ましい。
なお、ボイラ缶の上流側及び/又は下流側にpH測定手段を設け、該手段と、ポリアクリル酸又はその塩の添加手段との関連付けを行うことにより、適切な重量平均分子量のポリアクリル酸を自動的に選択して添加する構成をとることが好ましい。
本発明においては、本発明の目的が損なわれない範囲で、必要に応じて、蒸気発生設備の系内の何れかの箇所で、各種の添加成分、例えば、脱酸素剤、防食剤、スケール防止剤等を用いることができる。
スケール防止剤としては、例えば、各種リン酸塩、上述した条件を満たさないポリアクリル酸(重量平均分子量が低いもの)、ポリメタクリル酸、ポリマレイン酸、及びこれらのナトリウム塩等の水溶性高分子化合物、ホスホン酸塩、キレート剤等が挙げられる。これらの中でもポリメタクリル酸は、上述した条件を満たすポリアクリル酸又はその塩と組み合わせて用いることにより、ボイラ給水中の鉄濃度が0.3mg/Lを超えて含む場合、(例えば0.3~5.0mg/Lの高濃度の場合)のスケール除去効率を劇的に高めることができる点で好適である。
ポリメタクリル酸は、ボイラ水中での濃度が1~1,000mg/Lとすることが好ましく、10~500mg/Lとすることがより好ましい。また、ポリメタクリル酸は、ボイラ水中において、ポリアクリル酸(塩):ポリメタクリル酸(塩)の質量比が1:100~100:1、とりわけ1:50~50:1となるように添加するのが好ましい。
また、ポリメタクリル酸は、重量平均分子量が1,000~100,000以下であることが好ましく、5,000~60,000であることがより好ましい。ポリメタクリル酸は、重量平均分子量が1,000未満では十分な鉄スケール防止効果を得ることができない場合があり、ポリメタクリル酸の重量平均分子量が100,000を超えると効果が低下する。
下記の条件で、pH及びポリアクリル酸の重量平均分子量がスケール除去率に与える影響について検討した。
試験装置:ステンレス製テストボイラ
合成水A:給水中の濃度としてCa硬度:10mgCaCO3/L、Mg硬度:5mgCaCO3/L、シリカ15mg/L、炭酸ナトリウム25mg/L
合成水B:給水中の濃度としてシリカ15mg/L、表1記載の重量平均分子量のポリアクリル酸を20mg/L(ボイラ缶内濃度として200 mg/L)、表1記載のボイラ水pHとなるように炭酸ナトリウムを給水に添加
給水温度:40℃
運転圧力:2.0MPa
給水量:9L/h
濃縮倍率:10倍
スケール除去率の測定:試験前の伝熱チューブ(鋼材製、表面積200cm2×3本)を秤量し記録する。ステンレス製テストボイラ(保有水量5L)に、ボイラ缶内濃度10倍濃縮相当(合成水Aの10倍濃縮相当)の合成水を調製して投入し、合成水Aを給水しながら圧力2.0MPa、蒸発量8.2L/h、ブロー量0.8L/h、濃縮倍率10倍となるようにして21時間運転した。運転後にスケールが付着した伝熱チューブ(鉄製、表面積200cm2×3本)を取り出し秤量し、スケール付着量を算出した。その後、伝熱チューブを再度挿入し、缶内に合成水Bの10倍濃縮相当の合成水を調製して投入し、合成水Bで3日間、同じ条件で運転し、スケール除去工程を行った。運転後に同様に伝熱チューブを秤量し、スケール除去工程前後のスケール付着量からスケール除去率を算出した。結果を表1に示す。また、図2に、pHごとの、ポリアクリル酸の重量平均分子量とスケール除去率との関係を示す。
図3は、各pHでの最適なポリアクリル酸の重量平均分子量を示す図である。図3より、pH11.3と~pH12.0の間では略直線的な関係が認められることが分かる。
略直線的関係であるpH11.3と~pH12.0の区間の最小二乗法を行うと、切片が61,538、傾きが-8,462となる。
図4は、pH11.3~12.0の領域における、pHと、スケール除去に最適なポリアクリル酸の重量平均分子量との関係の最小二乗法による図である。スケール除去率を高めるためには、pHとの関係で、図4の直線(下記計算式(1))を基準としてポリアクリル酸の重量平均分子量を決定すればよいことが分かる。
基準重量平均分子量 = -8462×(pHの値-11.3)+61538 ・・・(1)
以上の結果から、ボイラ水のpHの値に応じて、上記計算式(1)から導かれる基準重量平均分子量の0.50~2.00倍の重量平均分子量を有するポリアクリル酸又はその塩を添加するという条件を満たすことにより、スケール除去率を高めることができることがわかる。
上記試験例では、試験例1-7、1-8、1-9、1-12、1-13、1-14、1-17、1-18及び1-19が該条件を満たしており、pHが同一である他の試験例に比べてスケール除去率が良好であることが分かる。
下記の条件で、ポリアクリル酸及び薬剤濃度がスケール除去率に与える影響について検討した。
試験装置 :ステンレス製テストボイラ
合成水C:給水中の濃度としてCa硬度:20mgCaCO3/L、Mg硬度:10mgCaCO3/L、シリカ15mg/L、炭酸ナトリウム35mg/L
合成水D:給水中の濃度としてシリカ15mg/L、炭酸ナトリウム20mg/Lとなるように添加し、表2記載の薬剤を表2記載のボイラ缶内濃度となるように給水に添加
給水温度:40℃
運転圧力:2.0MPa
給水量:9L/h
濃縮倍率:10倍
スケール除去率の測定:試験前の伝熱チューブ(鋼材製、表面積200cm2×3本)を秤量し記録する。ステンレス製テストボイラ(保有水量5L)に、ボイラ缶内濃度10倍濃縮相当(合成水Cの10倍濃縮相当)の合成水を調製して投入し、合成水Cを給水しながら圧力2.0MPa、蒸発量8.2L/h、ブロー量0.8L/h、濃縮倍率10倍となるようにして21時間運転した。運転後にスケールが付着した伝熱チューブ(鉄製、表面積200cm2×3本)を取り出し秤量し、スケール付着量を算出した。その後、伝熱チューブを再度挿入し、缶内に合成水Dの10倍濃縮相当の合成水を調製して投入し、合成水Dで6日間、同じ条件で運転し、スケール除去工程を行った。運転後に同様に伝熱チューブを秤量し、スケール除去工程前後のスケール付着量からスケール除去率を算出した。結果を表2に示す。
上記試験例では、試験例2-9~2-22が本発明のポリアクリル酸の重量平均分子量の条件を満たしており、ポリアクリル酸の濃度が同一である他の試験例に比べてスケール除去率が良好であることが分かる。
試験例2と同様の条件で、合成水D(ただし、薬剤の種類、分子量、ボイラ缶内濃度は表3の条件のもの)を用いてスケール除去を行っている際に、ボイラ缶内に鋼材製のテストピース(SGP、15×50×10mm、♯400研磨)を設置して、試験後に脱錆処理し、下記計算式(2)により腐食速度を求めた。
腐食速度(mdd)=テストピースの腐食減量(mg)/テストピースの表面積(dm2)×試験期間(day)
(全スケール除去率)
合成水Cに対して、鉄濃度が1.5mg/Lとなるように、塩化鉄と水酸化鉄とを1:1の質量割合で添加してなる合成水Fを給水として用いた以外は、試験例2と同様の条件で、伝熱チューブ(鋼材製、表面積200cm2×3本)を有するテストボイラを21時間運転した。運転後に、伝熱チューブの3本のうちの1本を取り出し、研磨された伝熱チューブに交換した。また、取り出した伝熱チューブを秤量し、スケール付着量を算出した。
次いで、合成水Dに対して、鉄濃度が1.5mg/Lとなるように、塩化鉄と水酸化鉄とを1:1の質量割合で添加してなり、かつ薬剤を表4に記載の薬剤、分子量、ボイラ缶内濃度のものに変更してなる合成水Gを給水として用いた以外は、試験例2と同様の条件で、6日間テストボイラを運転し、スケール除去工程を行った。追加運転後に先の運転後に交換していない伝熱チューブを秤量し、スケール除去工程前後のスケール付着量から全スケール除去率を算出した。結果を表4に示す。
2:補給水タンク 21:補給水ライン
3:給水タンク 31:給水ライン
4:ポリアクリル酸又はその塩
5:アルカリ剤
6:蒸気発生部(ボイラ缶)61:ドレン回収ライン
7:蒸気発生設備
Claims (3)
- 蒸気発生設備において、ボイラの稼働中に、ボイラ水のpHを11.3以上に調整し、かつボイラ水のpHの値に応じて、下記計算式(1)から導かれる基準重量平均分子量の0.50~2.00倍の重量平均分子量を有するポリアクリル酸又はその塩を添加することにより、ボイラ缶内に付着したスケールを除去する、蒸気発生設備のスケール除去方法。
基準重量平均分子量 = -8462×(pHの値-11.3)+61538 ・・・(1) - 蒸気発生設備において、ボイラの稼働中に、ボイラ水のpHを11.3以上に調整し、かつボイラ水のpHの値に応じて、下記の手法により算出される基準重量平均分子量の0.50~2.00倍の重量平均分子量を有するポリアクリル酸又はその塩を添加することにより、ボイラ缶内に付着したスケールを除去する、蒸気発生設備のスケール除去方法。
[基準重量平均分子量の算出方法]
(1)pH11.3以上の少なくとも3つのpH値において、スケール除去率が最大となるポリアクリル酸の重量平均分子量(Mwmax)を測定する。
(2)pHをx軸、Mwmaxをy軸として、最小二乗法によりpHとMwmaxとの関係式を求め、該関係式から得られる各pHでの重量平均分子量を、基準重量平均分子量とする。 - 前記ポリアクリル酸又はその塩を、前記ボイラ水中での濃度が10~500mg/Lとなるように添加する、請求項1または2に記載の蒸気発生設備のスケール除去方法。
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WO2015122264A1 (ja) * | 2014-02-13 | 2015-08-20 | 栗田工業株式会社 | 蒸気発生設備のスケール除去方法及びスケール除去剤 |
WO2016139837A1 (ja) * | 2015-03-04 | 2016-09-09 | 三菱日立パワーシステムズ株式会社 | 貫流ボイラの火炉壁管の洗浄方法 |
Families Citing this family (5)
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JP6631147B2 (ja) * | 2015-10-14 | 2020-01-15 | 栗田工業株式会社 | ボイラ給水用水処理装置及びボイラの運転方法 |
US20190084856A1 (en) * | 2017-09-20 | 2019-03-21 | Solenis Technologies, L.P. | Composition and method of scale control in regulated evaporative systems |
CN112694951A (zh) * | 2020-12-03 | 2021-04-23 | 嘉兴沃特泰科环保科技股份有限公司 | 一种非磷酸系中、低压锅炉清洗剂及其制备方法 |
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Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59189998A (ja) * | 1983-04-12 | 1984-10-27 | ケメツド・コ−ポレ−シヨン | スケ−ルの除去方法 |
JPH04193971A (ja) | 1990-11-28 | 1992-07-14 | Mitsubishi Heavy Ind Ltd | スケールの除去組成物 |
JP2000080396A (ja) * | 1998-07-02 | 2000-03-21 | Nippon Shokubai Co Ltd | 洗剤ビルダ―、その製造方法、及びポリ(メタ)アクリル酸(塩)系重合体ならびにその用途 |
JP2000154996A (ja) | 1998-08-19 | 2000-06-06 | Miura Co Ltd | ボイラのスケ―ル除去方法 |
JP2004027060A (ja) * | 2002-06-26 | 2004-01-29 | Jsr Corp | 水溶性共重合体及び純シリカスケール防止剤 |
JP2007038120A (ja) * | 2005-08-02 | 2007-02-15 | Nippon Shokubai Co Ltd | 亜鉛水酸化物スケール防止剤及び亜鉛水酸化物のスケール防止方法 |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3890228A (en) * | 1973-04-13 | 1975-06-17 | Chemed Corp | Polyacrylate-polyphosphonic acid treatment in aqueous systems |
US4575425A (en) * | 1984-12-24 | 1986-03-11 | Calgon Corporation | Process for controlling calcium oxalate scale over a wide pH range |
US4711726A (en) * | 1986-12-29 | 1987-12-08 | Nalco Chemical Company | Carboxylate N-vinylamide copolymers for internal scale control and passivation in high pressure boiler systems |
US5024783A (en) | 1989-10-10 | 1991-06-18 | Fremont Industries, Inc. | Boiler and boiler water treatment system |
JPH0663590A (ja) | 1992-06-29 | 1994-03-08 | Japan Synthetic Rubber Co Ltd | スケール除去剤及びそれを用いたスケール除去方法 |
US5403493A (en) * | 1992-12-10 | 1995-04-04 | Nalco Chemical Company | Noncorrosive scale inhibitor additive in geothermal wells |
IT1280182B1 (it) | 1995-06-05 | 1998-01-05 | Cirs Spa | Procedimento di polimerizzazione di monomeri |
US6297336B1 (en) | 1998-07-02 | 2001-10-02 | Nippon Shokubai Co., Ltd. | Detergent builder, production process therefor, and poly(meth)acrylic acid (or salt) polymer and use thereof |
CA2280586A1 (en) * | 1998-08-19 | 2000-02-19 | Miura Co., Ltd. | Method for removing scale of boiler |
US6790664B2 (en) | 2001-12-28 | 2004-09-14 | Nalco Company | Fluorometric monitoring and control of soluble hardness of water used in industrial water systems |
-
2014
- 2014-03-27 JP JP2014553375A patent/JP5773091B2/ja active Active
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- 2014-03-27 KR KR1020157027187A patent/KR101830234B1/ko active IP Right Grant
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Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59189998A (ja) * | 1983-04-12 | 1984-10-27 | ケメツド・コ−ポレ−シヨン | スケ−ルの除去方法 |
JPH04193971A (ja) | 1990-11-28 | 1992-07-14 | Mitsubishi Heavy Ind Ltd | スケールの除去組成物 |
JP2000080396A (ja) * | 1998-07-02 | 2000-03-21 | Nippon Shokubai Co Ltd | 洗剤ビルダ―、その製造方法、及びポリ(メタ)アクリル酸(塩)系重合体ならびにその用途 |
JP2000154996A (ja) | 1998-08-19 | 2000-06-06 | Miura Co Ltd | ボイラのスケ―ル除去方法 |
JP2004027060A (ja) * | 2002-06-26 | 2004-01-29 | Jsr Corp | 水溶性共重合体及び純シリカスケール防止剤 |
JP2007038120A (ja) * | 2005-08-02 | 2007-02-15 | Nippon Shokubai Co Ltd | 亜鉛水酸化物スケール防止剤及び亜鉛水酸化物のスケール防止方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2982655A4 |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015122264A1 (ja) * | 2014-02-13 | 2015-08-20 | 栗田工業株式会社 | 蒸気発生設備のスケール除去方法及びスケール除去剤 |
US10384966B2 (en) | 2014-02-13 | 2019-08-20 | Kurita Water Industries Ltd. | Method for removing scale and scale remover in steam generating facility |
WO2016139837A1 (ja) * | 2015-03-04 | 2016-09-09 | 三菱日立パワーシステムズ株式会社 | 貫流ボイラの火炉壁管の洗浄方法 |
CN107208879A (zh) * | 2015-03-04 | 2017-09-26 | 三菱日立电力系统株式会社 | 直流锅炉的火炉壁管的清洗方法 |
CN107208879B (zh) * | 2015-03-04 | 2019-05-03 | 三菱日立电力系统株式会社 | 直流锅炉的火炉壁管的清洗方法 |
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