CN1262487C - Method for removing boiler scale - Google Patents
Method for removing boiler scale Download PDFInfo
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- CN1262487C CN1262487C CN 99119632 CN99119632A CN1262487C CN 1262487 C CN1262487 C CN 1262487C CN 99119632 CN99119632 CN 99119632 CN 99119632 A CN99119632 A CN 99119632A CN 1262487 C CN1262487 C CN 1262487C
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- incrustation
- feedwater
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Abstract
The invention provides a method for removing scale during operation of a boiler by adding a chemical into boiler water. In the method, a total concentration of a chelating agent and a dispersant in the boiler water is regulated to a specified concentration under a condition that the boiler water is neutral or alkaline.
Description
The present invention relates to a kind of method of removing boiler scale, further say, relate to the method for in boiler operatiopn, removing incrustation.
In the boiler attendance process, can deposit hard water-fast crystalline solid gradually in water pipe or in the heat conductive wall, this solid is called incrustation.For instance, hard thing such as lime carbonate, CaCO
3With calcium sulfate CaSO
4With the solubleness that can not be increased in the water, and in some cases, it is insoluble to become when water temperature increases, so these become branches because the concentrated of heating and water is deposited on the heat conductive wall, thereby is deposited on the heated wall as incrustation.The salt that can take place not too to dissolve easily in water also, as Calcium hydrogen carbonate, Ca (HCO
3)
2Owing to heating is transformed into water-fast salt, i.e. lime carbonate, CaCO
3Thereby, cause incrustation.
Except hard thing such as calcium salt and magnesium salts, alkaline incrustation material can also be a silicon-dioxide, SiO
2The silicon-dioxide that is included in most surface waters will combine with hard thing and other metal ion such as zinc, aluminium and iron, form incrustation.For instance, when silicon-dioxide combined with hard thing, they can be created in the material that has in the high-temperature water than low solubility, and this material can and concentrate owing to heating and be deposited on the heat conductive wall, thus formation incrustation.In addition; iron is brought in the system with the form of oxyhydroxide and oxide compound; thereby produce floating particle or gel, these particles or gel can be deposited on the heat conductive wall and owing to repeat constantly dry and wetting or other technology and dried and solidify, thereby cause incrustation.
In case be deposited on the heat conductive wall, incrustation will cause variety of issue.At first, make fuel consumption increase because low the arriving of the thermal conductivity of incrustation is percentum of supplying pipe (ball-mill steel), and the incrustation that is deposited on the heat conductive wall will reduce combustion flame water in water pipe, and promptly feedwater is heat passage, thereby reduces thermo-efficiency greatly.In addition, in case flame reduces to the heat transfer of feedwater, the temperature of heat conductive wall can raise and the metal strength of heat conductive wall will descend.Because water pipe inside is in high pressure usually, the metal strength of heat conductive wall can not be born the internal pressure in the water pipe, and this will cause, and water pipe expands, breaks, fracture or other accident.
In order to prevent incrustation, people take such certain methods, for example come softening water inlet by water softening apparatus or other device, by emission control the concentration of the composition that forms incrustation are remained in its solubility range, perhaps make hard thing and deposition agent form slag charge.These methods are done detailed explanation below.At first thereby the method for softening boiler feed water by water softening apparatus or other device is a kind ofly to make the hard thing that forms incrustation in the boiler feed water such as calcium ion and magnesium ion be replaced as sodium ion to remove, prevent thus the sedimentary method of incrustation by the Zeo-karb in the soft device of water.
In addition, the concentration that will form the composition of incrustation by emission control the method in its solubility range of remaining on is a kind of feedwater regularly to be discharged into the method that the system outside is conscientiously controlled, thereby the concentration that forms the composition of incrustation in the feedwater is remained in their solubility range, prevent the incrustation deposition thus.But excessive discharging will cause the problem that boiler furnace is more perishable and thermosteresis is too big.
In addition, the method that makes hard material composition and precipitating agent form slag charge is a kind ofly to adopt a kind of reagent will expect to be transformed into the method for slag charge firmly away from the easy place that forms the water pipe internal surface of incrustation before forming incrustation by hard material, this slag charge has than lower water-soluble of incrustation, then the slag charge that produces is discharged and removes from this system when discharging each time, take place thereby suppress incrustation.This method adopts phosphate base reagent as reagent usually, but recent years people phosphorus has been formulated more and more stricter emission regulation, so this method is difficult to carry out.
As above said, people have adopted methods for preventing incrustation deposition, but these methods are difficult to prevent fully the incrustation deposition, so people need remove sedimentary incrustation.Incrustation is too hard, so that can not remove with mechanical means, therefore removes by pickling usually.For the incrustation of only forming, can adopt the method that adds hydrochloric acid and heating to dissolve and remove incrustation by hard thing.For the another kind of incrustation that combines by hard thing and silicon-dioxide, owing to this incrustation can not only be removed by hydrochloric acid, therefore need be by adopting hydrochloric acid and fluorochemical to dissolve and removing incrustation.For the iron-based incrustation that is produced by iron cpd, needs adopt citric acid to dissolve and remove incrustation in addition.
But when carrying out pickling, boiler must be stopped work and can be produced some problems, and for example boiler material iron is owing to the effect of acid is corroded.In addition, when adopting hydrochloric acid, during particularly fluorine-based reagent, because they exist higher danger must handle these reagent very carefully.
Although people adopt the reagent of mainly being made up of phosphonic acids to remove incrustation in boiler attendance, if these reagent are tart and they are joined in the feedwater in a large number that they will cause corrosion to boiler furnace.Therefore, people need a kind ofly to adopt neutrality or alkaline reagents effectively to remove incrustation but can not cause the method for above-mentioned etching problem, and said reagent can guarantee the water quality of normal feedwater.
Consider these and other some problem, the object of the present invention is to provide a kind of method of in the operation boiler, removing incrustation by in feedwater, adding reagent.
In order to reach this purpose, according to the present invention, it provides a kind of method of removing boiler scale, it is characterized in that the total concn of sequestrant in the feedwater and dispersion agent is adjusted to particular concentration at feedwater under for neutral or alkaline condition.
In one embodiment of the present invention, this sequestrant is any compound or two or more combination of compounds that is selected from following ingredients:
A) ethylenediamine tetraacetic acid (EDTA) (EDTA) and/or its salt;
B) polyalkylene polyamine and/or its salt;
C) two pyridines and/or its salt;
D) glycine and/or its salt;
E) methyl ethyl diketone;
F) nitrilotriacetic acid(NTA) (NTA) and/or its salt;
G) amino three (methyl acid phosphates) and/or its salt; And
H) 1-hydroxy ethylene-1,1-bisphosphate and/or its salt.
In one embodiment of the present invention, this dispersion agent is any compound or two or more combination of compounds that is selected from following ingredients:
A) polymaleic acid and/or its salt;
B) 2-phosphinylidyne butane-1,2-4-tricarboxylic acid (PBTC) and/or its salt;
C) two (poly--the 2-propyloic) phospho acid and/or its salt;
D) phosphinocarboxylic acid's multipolymer and/or its salt;
E) acrylamide acrylate copolymer and/or its salt; And
F) polyacrylic acid and/or its salt.
In one embodiment of the present invention, the total concn of sequestrant in the feedwater and dispersion agent is 500-5000ppm.
In addition, in embodiment of the present invention, sequestrant and dispersion agent weight ratio are 3: 97-97: 3.
The incrustation that Fig. 1 is illustrated in first kind of embodiment of the present invention is removed effect; And
The incrustation that Fig. 2 is illustrated in second kind of embodiment of the present invention is removed effect.
Embodiment of the present invention are described below.In boiler operatiopn, the scale remover that will contain sequestrant and dispersion agent joins in the feedwater in the present invention.Further say,, scale remover is placed in the chemical vessel, operate the pump of this agent delivery device, thereby this scale remover is sprayed in the boiler feed water by an agent delivery device is set on the boiler water supply pipeline.In this adding, can add some other reagent simultaneously, as oxygen scavenqer.
The present invention obtains following discovery through arduous research and realizes.These find following said.At first remove in the method for incrustation in the operation boiler, the bulk incrustation that the too high incrustation speed of removing can cause being removed is deposited in narrow positions such as water pipe, and this can make water pipe stop up.The too low conversely speaking, incrustation speed of removing can make thermo-efficiency descend and make phenomenons such as water pipe expands, ruptures, breaks.Therefore, the speed that incrustation is removed should be in a suitable level, thereby can avoid the problems referred to above.In addition, sequestrant has the function of dissolving incrustation really, but it is easy to make dissolved incrustation to deposit once more, will cause water pipe to stop up like this.In addition, dispersion agent has the function of disperseing and removing incrustation, but lower on incrustation speed.Found that by these inventor has invented a kind of method of removing incrustation, it is by add the composition of specific sequestrant and specific dispersion agent in feedwater.
For the present invention, sequestrant is meant to have and two or morely can forms the binding site of coordinate bond with metal ion and be water-soluble compound.The example of sequestrant can be ethylenediamine tetraacetic acid (EDTA) (EDTA), as polyalkylene polyamine, as quadrol, propylene diamine, Diethylenetriamine and three second tetramines, two pyridine, glycine, methyl ethyl diketone, nitrilotriacetic acid(NTA) (NTA), amino three (methyl acid phosphates), 1-hydroxyl ethylidene-1, the salt of 1-bisphosphate or the like and these compounds (except methyl ethyl diketone).Wherein, ethylenediamine tetraacetic acid (EDTA) (EDTA) and nitrilotriacetic acid(NTA) (NTA) and their salt are preferred.
Next, the example of dispersion agent is polymaleic acid, 2-phosphinylidyne butane-1,2,4-tricarboxylic acid (PBTC), two (poly--the 2-propyloic) phospho acid, phosphinocarboxylic acid's multipolymer, acrylamide acrylate copolymer, sodium polyacrylate or the like and their salt.
Wherein, for removing incrustation of forming by hard thing and carbonate or oxyhydroxide and the incrustation of forming by hard thing and silicon-dioxide (hereinafter referred to as hard thing/silicon dioxide base incrustation); polymaleic acid, 2-phosphinylidyne butane-1; 2; 4-tricarboxylic acid (PBTC), two (poly--the 2-propyloic) phospho acid, 1-hydroxyl ethylidene-1,1-bisphosphate, acrylamide acrylate copolymer, sodium polyacrylate or the like and their salt are particularly preferred.In addition, for removing the iron-based incrustation of being made up of iron cpd, two (poly--the 2-propyloic) phospho acid and phosphono-carboxylic acids multipolymer and their salt are preferred, and two (poly--the 2-propyloic) phospho acid or its salt are particularly preferred.
The ratio of sequestrant and dispersion agent is 3 in this scale remover: 97-97: 3, be preferably 15: 85-85: and 15, more preferably be 25: 75-75: 25.
This scale remover is by can be water-soluble, it be make as the aqueous solution and deposit with standby.The concentration of sequestrant and dispersion agent is respectively 1-40% weight usually in the aqueous solution, but there is no particular limitation to this.This scale remover can be by making sequestrant and dispersant, the sequestrant of specific quantity and dispersion agent can be added and be distributed to usually in water, another kind of water-containing solvent or its analogue and obtain this scale remover.Can with sequestrant be dissolved in the water after dispersion agent mixes together.
Can also add the benzyl chlorination sulfonium that corrodes draw up agent such as dimethyl-para-orientation in this scale remover, its add-on can not influence purpose of the present invention.
Can also add some other component in this scale remover, its add-on can not influence goal of the invention of the present invention.The example of these other component is the pH regulator agent, as sodium hydroxide, potassium hydroxide, yellow soda ash, salt of wormwood.Because it is acid that above-mentioned sequestrant and dispersion agent are, add can neutralize this acidity and make this scale remover be neutrality of these pH regulator agent.
This scale remover is joined in the feedwater, thereby make its concentration in feedwater remain on 500-5000ppm, be preferably 2000-3000ppm.An example of this adition process is to be 10% o'clock at discharge rate, adds this scale remover continuously.Thereby making scale remover is 200-300ppm with respect to the total amount of feedwater.Another example is this scale remover to be concentrated add, and is 2000-3000ppm thereby make scale remover with respect to the total amount of feedwater, and feedwater is discharging fully regularly.
To describe object lesson of the present invention in detail below.But the present invention is not limited to these embodiment.When describing these examples, term " part " is meant weight part.
Said scale remover below at first preparing four kinds.As first kind of reagent, 15 parts of disodium ethylene diamine tetraacetate (EDTA), 7.5 parts of polymaleic aciies, 6 parts of sodium hydroxide and 71.5 parts of water are mixed and be dissolved in together, make a kind of scale remover (reagent A hereinafter referred to as) thus.In addition, 15 parts of disodium ethylene diamine tetraacetate (EDTA), 6 parts two (poly--the 2-propyloic) phospho acid, 4.1 parts of sodium hydroxide and 74.9 parts of water are mixed and be dissolved in together, make a kind of scale remover (reagent B hereinafter referred to as) thus.In addition, with 15 parts of disodium ethylene diamine tetraacetate (EDTA), 9 parts of 1-hydroxyl ethylidene-1,1-diphosphate, 3 parts of potassium hydroxide and 73 parts of water mixing also are dissolved in together, make a kind of scale remover (reagent C hereinafter referred to as) thus.In addition, 15 parts of disodium ethylene diamine tetraacetate (EDTA), 9 parts of acrylamide acrylate copolymers, 1 part of polyacrylic ester and 75 parts of water are mixed and be dissolved in together, make a kind of scale remover (reagent D hereinafter referred to as) thus.
Next, first embodiment of the present invention is described.Be about to add in 0.15 liter the boiler (pilot boiler) to pondage and contain the softening water of the hard thing of 0.4ppm and operation under atmospheric pressure, formed incrustation of forming by hard thing and carbonate and the incrustation of forming by hard thing and silicon-dioxide in this boiler.In this operating process, with the reagent A adding and every 2 hours feedwater is poured out fully, the concentration in the feedwater remains under the 2000-3000ppm simultaneously.In this case, the pH value in the feedwater is about 11.5.Removing of measuring after the operation in 8 hours the results are shown among Fig. 1.In addition, replace reagent A to carry out same operation with reagent B or C, and, do not add any reagent and carry out same operation in order to compare.The result of these situations is shown among Fig. 1 together.Can obviously find out by Fig. 1, adopt reagent of the present invention can obtain good especially descale effect.Especially, adopt polymaleic acid good especially as its performance of reagent A of dispersion agent.Compare with it, its scale removal of the situation result who does not add reagent is zero.
Next, second embodiment of the present invention described.Be about to add in 0.15 liter the boiler (pilot boiler) to pondage and contain the softening water of the hard thing of 0.4ppm and operation under atmospheric pressure, formed the incrustation of forming by iron cpd in this boiler.In this operating process, with reagent B adding and every 2 hours feedwater is poured out fully, the concentration in the feedwater remains under the 2000-3000ppm simultaneously.In this case, the pH value in the feedwater is about 11.5.Removing of measuring after the operation in 8 hours the results are shown among Fig. 2.In addition, replace reagent B to carry out same operation with reagent A or C, and, do not add any reagent and carry out same operation in order to compare.The result of these situations is shown among Fig. 2 together.Can obviously be found out by Fig. 2, adopt reagent B can obtain good especially descale effect, this reagent is reagent of the present invention and adopts two (poly--the 2-propyloic) phospho acid as dispersion agent.In this embodiment, its scale removal of the situation result who does not add reagent is zero.
As above said, by keep the certain density scale remover of being made up of sequestrant and dispersion agent in the boiler attendance process, scale remover of the present invention can obtain fabulous descale effect.
Above said sequestrant have the binding site of some and metallic ion coordination.These binding sites are Sauerstoffatoms in the Sauerstoffatom, nitrogen-atoms, phosphate radical in the carboxylate radical etc.Ligand be electrical basically in conjunction with energy, it is total to belong to ligand.Therefore all can obtain identical effect adopting under two kinds of situations of single sequestrant and two or more sequestrants of employing.
In addition, people have known that dispersion agent can prevent that the incrustation nuclear phase from combining mutually when adopting dispersion agent to prevent incrustation usually.The reason that the bound energy of sequestrant and dispersion agent reaches outstanding descale effect can think to be chelated incrustation that agent removes because dispersion agent and keep fine particle in feedwater.Therefore all can obtain identical effect adopting under two kinds of situations of single sequestrant and two or more sequestrants of employing.
As above said, according to the present invention, it provides a kind of method that can remove boiler scale by adding reagent in feedwater under normal operation, and it need not to stop boiler.Therefore descaling method of the present invention in addition is nontoxic, and it can be included in the pickling, has high security, and it can also carry out under feedwater is neutral, alkaline condition in addition, therefore can not make boiler that any corrosion takes place.In addition, descaling method of the present invention has suitable scale removal speed, thereby therefore can solve the incrustation of being removed preferably and be deposited on the problem that the water pipe narrow positions is blocked the water pipe generation, and solve problems such as thermo-efficiency descends and water pipe expands, ruptures, breaks.
Claims (1)
1. method of removing boiler scale, this method comprise, in feedwater, add scale remover continuously so that in the feedwater amount of scale remover be 500-5000ppm, described scale remover comprises:
A. be selected from least a compound of ethylenediamine tetraacetic acid (EDTA) and salt thereof;
B. be selected from least a compound of polyacrylic acid, acrylamide acrylate copolymer and salt thereof;
C. be selected from least a compound of sodium hydroxide and potassium hydroxide; With
D. water;
The weight ratio of above-mentioned A and B is 3: 97-97: in 3 scopes, described feedwater has pH7 or higher; With
During boiler operatiopn with the scale remover scale removal.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP250406/98 | 1998-08-19 | ||
| JP25040698 | 1998-08-19 | ||
| JP250406/1998 | 1998-08-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1252388A CN1252388A (en) | 2000-05-10 |
| CN1262487C true CN1262487C (en) | 2006-07-05 |
Family
ID=17207432
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 99119632 Expired - Lifetime CN1262487C (en) | 1998-08-19 | 1999-08-19 | Method for removing boiler scale |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN1262487C (en) |
| CA (1) | CA2280586A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060046953A1 (en) * | 2004-09-02 | 2006-03-02 | Charkhutian Kostan B | Process for inhibiting scale on metal surfaces |
| CN105102380B (en) * | 2013-04-02 | 2019-06-18 | 栗田工业株式会社 | The descaling method of steam generating equipment |
| CN103965098A (en) * | 2014-05-22 | 2014-08-06 | 山东昆达生物科技有限公司 | Energy saving technology in pyridine and 3-methylpyridine preparation processes |
| CN109354221A (en) * | 2018-10-29 | 2019-02-19 | 爱环吴世（苏州）环保股份有限公司 | A kind of ooze regulator for removing the old old dirt of boiler system |
| CN110241430A (en) * | 2019-06-27 | 2019-09-17 | 湖南省湘电试验研究院有限公司 | A kind of composite organic acid contaminant removing cleaning agent and its application |
-
1999
- 1999-08-19 CN CN 99119632 patent/CN1262487C/en not_active Expired - Lifetime
- 1999-08-19 CA CA002280586A patent/CA2280586A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CN1252388A (en) | 2000-05-10 |
| CA2280586A1 (en) | 2000-02-19 |
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