CN100436938C - Method for directly treating air cooling drum boiler unit water supply - Google Patents
Method for directly treating air cooling drum boiler unit water supply Download PDFInfo
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- CN100436938C CN100436938C CNB2006101020120A CN200610102012A CN100436938C CN 100436938 C CN100436938 C CN 100436938C CN B2006101020120 A CNB2006101020120 A CN B2006101020120A CN 200610102012 A CN200610102012 A CN 200610102012A CN 100436938 C CN100436938 C CN 100436938C
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 126
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000001816 cooling Methods 0.000 title claims description 41
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 27
- 239000001301 oxygen Substances 0.000 claims abstract description 27
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 26
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 17
- 239000001257 hydrogen Substances 0.000 claims abstract description 17
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 13
- 238000007599 discharging Methods 0.000 claims abstract description 12
- 238000012545 processing Methods 0.000 claims description 24
- 238000007254 oxidation reaction Methods 0.000 claims description 10
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- 238000005260 corrosion Methods 0.000 abstract description 22
- 230000007797 corrosion Effects 0.000 abstract description 22
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- 238000006213 oxygenation reaction Methods 0.000 description 38
- 229910052742 iron Inorganic materials 0.000 description 17
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 235000014171 carbonated beverage Nutrition 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
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- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
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- 241000370738 Chlorion Species 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000000205 computational method Methods 0.000 description 1
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- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
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- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
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- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
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- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
The present invention relates to boiler feed water treating technology, and is especially water treating method for directly air cooled steam drum boiler. Under the reductive condition, the condensed water from the condensing water tank is added with ammonia before entering the boiler directly under the condition of closing the oxygen discharging door of deaerator and the water hydrogen conductivity is controlled below 0.2microS/cm. In case of poor water quality, the oxygen discharging door is opened to convert into reductive mode. The present invention alters the traditional concept that dissolved oxygen will result in corrosion, and has double compact oxide film formed on surface of metal to inhibit the flow corrosion in thermal system, fine treatment of condensed water for long running time, no use of carcinogenic hydrazine and lowered ammonia adding amount for environment protection and health, and raised equipment utilization.
Description
Technical field
The present invention relates to the boiler feedwater processing technology field, be specially a kind of directly air cooled steam drum boiler unit feedwater treatment method.
Background technology
The large-scale thermal power machine group type of cooling commonly used is divided into recirculated water cooling and Direct Air-cooled Unit at present.Because Direct Air-cooled Unit reduce water consumption greatly, and addressing do not restrict by or not the water source, thus suit to promote in the water-deficient area, remove economize on water, all be better than the recirculated water cooling unit at aspects such as investment, operation, maintenances.As everyone knows, the directly air cooled steam drum boiler unit has its evident characteristic aspect chemical in practice: 1, the condensate water salt content is low and stable: adopt the air cooling, do not exist conventional water-cooled unit condenser to leak, pollute the problem of condensate water, though its condensate water salt content is starkly lower than conventional water-cooled unit, the condensate water dissolved oxygen is apparently higher than conventional water-cooled unit; 2, condensing water temperature height: because the back pressure of Air-cooled Unit is than water-cooled unit height, so the Air-cooled Unit condensing water temperature is than water-cooled unit height, Air-cooled Unit annual back pressure is higher than humid-cool system, cause the condensate water water temperature higher, and operating mode is changed greatly by extraneous meteorological effect, summer, condensing water temperature reached as high as 80 ℃, and the operation of condensate water accurate process equipment is affected.3, direct air cooling system is that full iron does not have the copper system, two essential conditions of the polishing unit of condensing is arranged, and water quality can guarantee that water treatment relatively is fit to alkaline oxygenated property operating mode in the stove.Present global Direct Air-cooled Unit quantity is increased sharply, account for 42% of whole Air-cooled Unit installed capacitys, but the standards and norms of still not having water chemistry technical field in the relevant stove both at home and abroad, carry out the research and the application of water technology in the directly air cooled steam drum boiler unit furnace for this reason, be of great practical significance.
The present common first-selected Direct Air-cooled Unit of the newly-built large-size thermal power plant in northern China water-deficient area.Processing great majority for directly air cooled steam drum boiler unit furnace water adopt phosphate treated PT (phosphatetreatment) operating mode, the feedwater method of operation that adds hydrazine and ammonia adjusting chemical characteristic is adopted in feedwater, be called reproducibility water treatment row operating mode (being that ammonification-oxygen scavenger is handled AVT-R): in water supply system, add ammonia and a kind of oxygen scavenger (as hydrazine), to regulate the pH value of working medium in water, the vapour system, make it to be alkalescent, and remove remaining dissolved oxygen in the feedwater.Under this processing mode, feedwater is in the atmosphere of reproducibility, common ORP＜-200mV.Fuel is in the boiler internal combustion, thereby make stove water be heated boiling and generation high temperature and high pressure steam, afterwards driving steam turbine rotates and mechanical energy is converted into electric energy output, when the exhaust steam of high temperature and high pressure steam after acting is admitted to air cooling tower, in air cooling tower, carry out direct heat transfer with the cooling air of sending into by axial flow blower, the condensate water that generates flows into condensate tank, dissolved oxygen amount in most Direct Air-cooled Unit condensate water is all greater than 30 μ g/L, surpass the industry specified standard, condensate water is successively through the condensate water accurate process equipment then, oxygen-eliminating device, enter boiler behind the economizer once more.Under the reproducibility operating mode, the oxygen discharging door of oxygen-eliminating device is opened and is carried out thermal de-aeration, needs twice oxygen scavenger of adding and ammonia to carry out chemical deoxidization in this process, has following defective in actual motion:
1, the steam after the steam turbine acting is forced to be cooled to condensate water through large-scale pipeline and fin, condensate water frigorimeter area is very big, there is more opportunity to contact the air that bleeds, thereby cause condensate water dissolved oxygen severe overweight, air cooling system material major part is a carbon steel, has the high problem of corrosion and iron-holder;
2, iron-holder is big in the water quality, and it is long to start washing time: the Direct Air-cooled Unit air cooling tower is very huge, and it is invested near capital equipments such as boiler, steam turbines, and the air cooling tower material is a carbon steel pipe, and outside employing galvanizing is handled.Because air cooling system is bigger than the metal heat exchange area of steam contact in the conventional humid-cool system, corrosion product is many, water system regiment commander iron is serious, particularly during the test run in the system Fe content bigger, unit outage starts air cooling tubes condenser after a period of time must be through big flow flushing, the cold conditions iron-holder just can drop to below the 1000 μ g/L, and iron content makes the precision processing burden, the cycle of operation is short, resin stain is serious, the carbonated drink quality descends, and threatens for the unit safety economical operation.Flushing brought difficulty before huge cooling system give to start, and made when starting the wash water amount more, and this starts generating rapidly for unit and will cause and have a strong impact on, and the expense of water is also very huge;
3, the problem of condensate water precision processing existence: condensate water iron content senior general causes the resin severe contamination, and resin exchange capacity will seriously descend, and the cycle of operation shortens, and water quality will be worsened.Exceed standard for powder precoat filter iron-holder and can cause also that filter core is dirty stifled poisons, shorten service life.Also have the very high problem of import powdex expense in addition,, prolong the condensate water precision processing cycle of operation from economy, also most important to reducing operating cost;
4, must add a large amount of carcinogen-hydrazines when deoxygenation, not only cause environmental pollution, production cost is higher, the more important thing is health has been caused serious threat;
5, the processing of stove water great majority adopt the phosphate treated operating modes, and this processing mode is when regulating pH value, and dosage is bigger, and easily produce phosphate and hide phenomenon, not only cause acid phosphate to corrode to boiler, and great majority are deposited on boiler internal, are difficult for removing.
Summary of the invention
The present invention is higher for the condensate water dissolved oxygen severe overweight in service, boiler feedwater hydrogen conductivity height, the iron-holder that solve existing directly air cooled steam drum boiler unit and adopt the reproducibility processing method to be caused, problems such as short and therrmodynamic system heating surface iron dirt deposition rate of the condensate water precision processing cycle of operation is big, and a kind of directly air cooled steam drum boiler unit feedwater treatment method of novel practical is provided.
The present invention adopts following technical scheme to realize: fuel is in the boiler internal combustion, stove water is heated boiling and produces high temperature and high pressure steam, afterwards driving steam turbine rotates and mechanical energy is converted into electric energy output, high temperature and high pressure steam after the acting is admitted to air cooling tower immediately, in air cooling tower, carry out direct heat transfer with the cooling air of sending into by axial flow blower, the condensate water that generates flows into condensate tank, innovative point of the present invention is that the condensate water that is flowed out by condensate tank directly enters boiler after adding ammonia under the oxygen-eliminating device oxygen discharging door closing state, and the hydrogen conductance that wherein feeds water is controlled at below the 0.2 μ S/cm.This processing method belongs to the oxidisability processing method, also claims AVT-O mode, and for guaranteeing the operation of AVT-O working condition safety, its precondition is that feedwater water quality must be pure, and the feedwater hydrogen conductivity is the index the most intuitively of water quality purity.Innovative point of the present invention has been broken the traditional concept that has dissolved oxygen to corrode that generally believes in the directly air cooled steam drum boiler machine set system.Under existing reproducibility operating mode, even water quality purity reaches the requirement of implementing the oxidisability operating mode fully, people also dare not go to adopt, and the present invention utilizes in the system dissolved oxygen in self condensate water to enter feedwater under flow regime to react with system's iron and generate Fe
2O
3And Fe
3O
4Form fine and close " double shielding film " at steel surface; the a series of defectives that exist under the reproducibility operating mode have been overcome fully; it is little to have had system's corrosion and scaling speed, and migration minimizing, the stove water salt content of corrosion product be low, need not make chemicals consumption minimizing with oxygen scavenger, boiler internal is clean and make remarkable advantage such as Chemical cleaning cycle stretch-out.Feedwater processing mode of the present invention is particularly useful for the Direct Air-Cooled dum boiler of subcritical parameter and supercritical parameter.
Unit of the present invention is under the situation of water quality inferiority, the hydrogen conductance that promptly feeds water remains on when 0.2 μ S/cm is above to be moved continuously, the oxygen discharging door of oxygen-eliminating device should be opened, compare and only carry out thermal de-aeration with the reduction operating mode, the hydrogen conductance of waiting to feed water drops to the oxygen discharging door that 0.2 μ S/cm closes oxygen-eliminating device when following again, carry out oxidisability and handle, realized the conversion between reduction operating mode and oxidation operating mode, guaranteed the normal stable operation of system.
Of the present invention in the whole service processing procedure, adopt industrial on-line oxidation reduction potential instrument to feed water and stove water condition on-line monitoring with regulate control, being used in time detecting feedwater and stove water is in oxidation state or goes back ortho states, judge water quality situation and in time regulating according to testing result, afterwards between oxidation operating mode and reduction operating mode, change, to reach Direct Air-cooled Unit feedwater processing requirements.
Stove hydromining of the present invention hydro-oxidation sodium processing mode, compare with traditional phosphate treated mode and to have the following advantages: 1, can form hydroxyl alkalescence diaphragm at boiler inner wall, can reduce the deposition of silicon in boiler on the one hand, also can reduce chlorion produces spot corrosion to the metal surface effect on the other hand; 2, because its alkalescence is stronger, so speed is very fast when regulating pH value, and dosage is few, and boiler water quality is improved, the blowdown flow rate minimizing.
The basic principle of feedwater oxidisability processing method of the present invention is as follows:
A) the formation mechanism of passivating film
In the anaerobic of AVT-R, when high pH value is handled, the ferriferous oxide that the metal surface that contacts with water in pure water covers mainly is Fe
3O
4, at Fe
3O
4In the forming process, progressively generated by the metal surface and to have stretched Fe in dense and thin to the metal inside oxidation
3O
4Layer, Fe
3O
4Layer gos deep into to metal inside from the initial surface of steel, and this film has certain dissolubility in the high temperature pure water, under the AVT-O mode, because constantly to steel surface oxygen supply equably, thereby make Fe
3O
4The rapid oxidation of ferrous ion that layer diffuses out forms the very low Fe of solubility
2O
3, at Fe
3O
4Particle surface and crystal grain gap deposition, sealed Fe
3O
4The surface of film and hole form fine and close " double shielding film " at steel surface, have reduced the speed of diffusion and oxidation, make the therrmodynamic system corrosion of metal obtain effective inhibition.
B) electrochemical principle
From electrochemical angle; in the high purity water that flows, add an amount of oxygen; can improve the spontaneous potential of steel; make metal surface generation polarization or make the spontaneous potential of metal surpass passivation potential; metal surface thereby form fine and close and stable oxidisability diaphragm, thus played the effect that suppresses steel corrosion.The AVT-O operating mode is because oxygenation has been accelerated Fe
3O
4In stretch the layer formation speed, at Fe
3O
4Generate one deck Fe again with the aqueous phase interface place
2O
3Layer makes Fe
3O
4Surface pore and groove are closed, thereby have formed more form compact and stable protective layer.The stable corrosion product that forms on AVT-O operating mode lower surface and aqueous phase interface is Fe
2O
3, its solubility has determined protective value.As everyone knows, the solubility of ferric iron compound is little more than ferrous solubility, usually the Fe that forms under the AVT-R condition
3O
4Have an appointment 15% micropore of layer, and the double-deck oxide-film that forms under the AVT-O condition is uniform and smooth, finer and close, can think: AVT-O regulates method and is preventing more to be better than phosphate aspect the steel corrosion and AVT-R regulates method.
Compare with traditional reproducibility operating mode, the present invention adopts the condensate water that is flowed out by condensate tank adding the feedwater oxidisability processing method that directly enters boiler behind the ammonia, and guarantee that feedwater hydrogen conductance is controlled at below the 0.2 μ S/cm, have remarkable economic efficiency and social benefit, specific as follows:
(1), boiler circuit iron copper content significantly descends the raising of carbonated drink quality
Under the AVT-O operating mode, the iron of boiler circuit, copper content reduce than AVT-R, and the hydrogen conductance of feedwater reduces more than 30% less than 0.2 μ S/cm when moving than the AVT-R operating mode, the carbonated drink quality improves a lot, and illustrates that the metal erosion of condensate water, water supply system is effectively suppressed;
(2), shut down corrosion and obviously alleviate, unit starting water washing time reduces, and shortens start-up time, reduces the wash water amount;
(3), the precision processing device cycle of operation prolongs
The polishing unit that condenses under the AVT-R operating mode mixes bed and on average operates to 3-7 days; After adopting the operation of AVT-O operating mode, the cycle of operation is about 20 days.The polishing unit cycle of operation prolongs owing to condense, and corresponding wastewater treatment and discharge capacity reduce, and water saving and environmental benefit are remarkable;
(4), conserve water treatment of pharmaceutical products expense
After adopting the AVT-O treatment technology, it is about 1/3 to reduce ammonia residual, stops to add carcinogenic substance-diamine, and annual unit is saved about 340,000 yuan of treatment of pharmaceutical products expense;
(5), the boiler heating surface scaling rate reduces the Chemical cleaning cycle stretch-out
Can find out that by the sedimentation rate that detects superheater, reheater and water-cooling wall evaporator section under the AVT-O operating condition, the therrmodynamic system metal material has formed fine and close, smooth diaphragm, metal erosion is effectively suppressed, and the heating surface scaling rate obviously descends;
(6), boiler heat-transfer efficient improves the set steady raising
Because under the AVT-O operating condition, the boiler heating surface scaling rate reduces, and the particle of dirt is more tiny, smooth, reduces boiler operatiopn pressure reduction, has improved the heat transfer efficiency of boiler; Help preventing that current accelerated corrosion (FAC) and boiler pipe explosion accident from taking place, the long-time running of unit energy continous-stable, security and stability and equivalent availability significantly improve.
In a word, the present invention utilizes in the system dissolved oxygen in self condensate water and iron reaction and has formed fine and close double-deck oxide-film, and can carry out the conversion of operating mode according to the quality of water quality purity, truly have the dissolving of the ferroelectric oxide film that suppresses water supply system and the effect of slowing down current accelerated corrosion (FAC); The boiler heat-transfer performance improves, and generatine set heat efficiency improves; Because the precision processing cycle of operation prolongs, reduced the wastewater treatment expense and to the pollution of environment, obviously improved energy-conservation, water saving and environment protecting, saved annual about 2,000,000 yuan of operating cost, obtained the remarkable result of unit safety economical operation and energy efficiency.
Description of drawings
Fig. 1 is the X-ray diffraction analytic curve of economizer before the oxygenation of the present invention
Fig. 2 is the X-ray diffraction analytic curve of economizer behind the oxygenation of the present invention
Fig. 3 is the X-ray diffraction analytic curve of water-cooling wall before the oxygenation of the present invention
Fig. 4 is the X-ray diffraction analytic curve of water-cooling wall behind the oxygenation of the present invention
Fig. 5 is ESEM (SEM) analysis chart of economizer inner surface before the oxygenation of the present invention, and multiplication factor is 300
Fig. 6 is ESEM (SEM) analysis chart of economizer inner surface behind the oxygenation of the present invention, and multiplication factor is 300
Fig. 7 is ESEM (SEM) analysis chart of economizer inner surface before the oxygenation of the present invention, and multiplication factor is 1000
Fig. 8 is ESEM (SEM) analysis chart of economizer inner surface behind the oxygenation of the present invention, and multiplication factor is 1000
Fig. 9 is ESEM (SEM) analysis chart of water-cooling wall inner surface before the oxygenation of the present invention, and multiplication factor is 300
Figure 10 is ESEM (SEM) analysis chart of water-cooling wall inner surface behind the oxygenation of the present invention, and multiplication factor is 300
Figure 11 is ESEM (SEM) analysis chart of water-cooling wall inner surface before the oxygenation of the present invention, and multiplication factor is 1000
Figure 12 is ESEM (SEM) analysis chart of water-cooling wall inner surface behind the oxygenation of the present invention, and multiplication factor is 1000
The specific embodiment
Fuel is in the boiler internal combustion, stove water is heated boiling and produces high temperature and high pressure steam, afterwards driving steam turbine rotates and mechanical energy is converted into electric energy output, high temperature and high pressure steam after the acting is admitted to air cooling tower immediately, in air cooling tower, carry out direct heat transfer with the cooling air of sending into by axial flow blower, the condensate water that generates flows into condensate tank, the condensate water that is flowed out by condensate tank directly enters boiler after adding ammonia under the oxygen-eliminating device oxygen discharging door closing state, the hydrogen conductance that wherein feeds water is controlled at below the 0.2 μ S/cm; Unit is opened the oxygen discharging door of oxygen-eliminating device under the situation of water quality inferiority; In the entire process process, adopt industrial on-line oxidation reduction potential instrument to feed water and stove water condition online detection and control; Stove hydromining hydro-oxidation sodium processing mode.
Example: is that example describes with the subcritical directly air cooled steam drum boiler unit feedwater of 300MW by the industrial experiment that the reproducibility processing mode is converted to oxidisability processing mode of the present invention.
One, experiment purpose:
Feed water original employing reproducibility of unit is handled operating mode, and the stove water initial stage is adopted Low Phosphates Treatment, and its industry rules control criterion is: feedwater pH=8.8～9.3; N
2H
410～50 μ g/L; DD
H≤ 0.3 μ S/cm; Dissolved oxygen＜7 μ g/L; Full iron＜10 μ g/L; Full copper＜5 μ g/L; Steam SiO
2＜20 μ g/L; Na＜10 μ g/L.The polishing unit 100% that condenses comes into operation, the general mixed bed operating cycle is 3～7 days, boiler feedwater water quality is qualified, after operation a period of time, find to exist following point: the higher relatively and condensate water dissolved oxygen severe overweight of feedwater iron-holder, the precision processing cycle of operation is shorter, the boiler heating surface scaling rate is very fast, the Chemical cleaning cycle is shorter, in order to address the above problem, reduce the fouling salification speed of boiler and steam turbine, improve the economy and the security of unit overall operation, having carried out handling change working by reproducibility is the industrial experiment that oxidisability is handled operating mode.
Two, experimentation:
This unit stops to add hydrazine earlier, enter the preparatory stage that feed water oxygenation is handled, carried out before the sampler oxygenation transforming and increased stove water and water supply system hydrogen electricity leads, the on-line detector table of ORP and dissolved oxygen etc., make the monitoring condition satisfy the requirement of AVT (O) water condition, readjusted and partly controlled index, feedwater pH is controlled between the 9.0-9.5 hydrogen conductivity≤0.2 μ S/cm, stove water pH is controlled between the 9.3-9.7, hydrogen conductivity≤1.5 μ S/cm.Move after one month, closed unit oxygen-eliminating device oxygen discharging door, use as heater, in condensate water and feedwater, only add little ammonia and control feedwater hydrogen conductivity then and directly send into boiler after less than 0.2 μ S/cm, adjusted part index number simultaneously: feedwater pH is controlled between the 9.0-9.6, and is consistent with the national standard of defined, and just the ammonia residual than reproducibility operating mode is littler in actual mechanical process, hydrogen conductivity≤0.15 μ S/cm, dissolved oxygen 10ug/L; Stove water PH is controlled between the 9.0-10.0, hydrogen conductivity≤1.5 μ S/cm, dissolved oxygen＜10 μ g/L.
Three, interpretation of result:
1, the variation of iron-holder in the therrmodynamic system
Since coming into effect the feedwater oxidisability and handling, the iron-holder of therrmodynamic system is totally on a declining curve, and after testing, 26 μ g/L during by AVT-R reduce to 8 μ g/L, the dissolving of the ferroelectric oxide film that suppresses water supply system is arranged really and slow down the effect of current accelerated corrosion.When unit AVT-O mode is moved; it is higher when the iron-holder of system begins; condensate water is handled through the powder precoat filter; just removed small part iron rot product; in conversion process; carry out oxygenation in the low pressure feed water system in advance and realize the oxidation state protection, reduced the corrosion of water supply system, also reduced the iron-holder of feedwater and stove water.
2, the condensate water precision processing mixes the cycle of operation of bed
When under the AVT-R operating mode, moving, the cycle of operation of condensate water accurate process equipment is 3～7 days, after transferring the AVT-O mode to and moving, significantly reduces with corrosion product and obviously lowers owing to add dose, make the cycle of operation of condensate water accurate process equipment prolong, the water production in periodic mode of every equipment has increased by 3 times.Year has been saved a large amount of import powdex and demineralized water, has also reduced discharging a large amount of regenerative wastewater accordingly simultaneously, has reduced the degree of environmental pollution.
3, the water quality situation during startup and shutdown of units
Under the reproducibility operating mode,, started water quality inferiority in the past because of operating load alters a great deal, start and stop are frequent, cold conditions flushing iron-holder is bigger before starting, up to 200～800 μ g/L, each washing time is longer, nearly more than 20 hours, with about 3000 tons of the desalination water yields, and when the unit starting of AVT-O operating mode operation back, washing time is promptly qualified less than 4 hours, and iron-holder is less than 100 μ g/L, shorten start-up time greatly, saved a large amount of demineralized waters.
4, boiler situation
Unit has carried out the therrmodynamic system pipe cutting in the AVT-R operating mode after operation a period of time and has taken a sample to check, from the metallographic examining report as can be seen: water-cooling wall, economizer tube sample inner surface main component are iron before the oxidisability that feeds water is handled, its epithelium is more loose, and hole is arranged, and recessed " usur hole " arranged; At the water supply system oxygenation after 4 months, the changing into of the epithelium success that it is surperficial with Fe
2O
3It is main diaphragm.That pipe sample inner surface forms under the AVT-O operating mode is the Fe of smoother densification
2O
3Epithelium.Concrete row examining report content as follows:
(1) X-ray diffraction analysis
A, economizer
By to before the oxygenation and under the AVT-O processing operating mode of oxygenation after 4 months, the economizer inner surface is carried out the X-ray diffraction analysis record curve shown in Figure of description 1, Figure of description 2.In addition, by the peak area at X-ray diffraction peak, and just obtained the shared relative scale of the various compositions of metal surface epithelium through calculating, these computational methods are that those of ordinary skill in the art is known.
According to Figure of description 1 and through calculating as can be known, the corrosion product of the economizer tubing inner surface under the reproducibility operating mode mainly is Fe, Fe
2O
3Content very low, undetected.
According to Figure of description 2 and through calculating as can be known, after 4 months, the corrosion product of economizer tubing inner surface mainly is Fe under the AVT-O operating mode at oxygenation
2O
3, its content accounts for 75-80%, Fe
3O
4Content less.As seen under the AVT-O operating mode Fe of oxygenation economizer tubing inner surface after four months great majority be converted into stable Fe
2O
3Film.
The B water-cooling wall
Before the oxygenation and the AVT-O of oxygenation after 4 months handle and under the operating mode water-cooling wall inner surface to be carried out the X-ray diffraction analysis and record curve shown in Figure of description 3, Figure of description 4.In addition, by the peak area at X-ray diffraction peak, obtained the shared relative scale of the various compositions of metal surface epithelium.
According to Figure of description 3 and through calculating as can be known, the corrosion product of the water-cooling wall tubing inner surface under the reproducibility operating mode mainly is Fe, Fe
2O
3Content very low, undetected.According to Figure of description 4 and through calculating as can be known, after 4 months, the corrosion product of water-cooling wall tubing inner surface mainly is Fe under the AVT-O operating mode at oxygenation
2O
3, its content accounts for about 70-75%, Fe
3O
4Proportion is less, only accounts for 20-25%.Can find out under the AVT-O operating mode, oxygenation after four months water-cooling wall tubing inner surface formed stable with Fe
2O
3It is main diaphragm.
Conclusion 1:
The economizer of this unit under the reproducibility operating mode, its main component of diaphragm epithelium of water screen tube sample inner surface are the Fe matrixes; After four months, economizer, its surperficial Fe of water-cooling wall successfully change into Fe in feedwater and therrmodynamic system oxygenation operation
2O
3Be main and smoother compact protective film.
(2) ESEM (SEM) is analyzed
The A economizer
Economizer tubing inner surface is analyzed with ESEM, and the result who draws is shown in Figure of description 5, Fig. 6, Figure of description 7, Figure of description 8.
The economizer tube sample inwall epithelium of unit oxygenation after four months checked.Be depicted as before the sample oxygenation of economizer tube and scanning picture during 300 times of the amplification of oxygenation after four months as Figure of description 5,6, as can be seen from Figure, the economizer tube sample inner surface particle diameter before going into operation is thicker, and is loose, and hole is arranged, and out-of-flatness.And the crystal grain that the economizer tube inside pipe wall under the operation of AVT-O operating mode forms is more tiny, even, does not have hole; From Figure of description 7,8: when economizer tube inner surface state was amplified to 1000 times, skin membrane had obviously recessed " usur hole " before the oxygenation, and skin membrane loosens, and crystal grain is bigger, and the surface does not have small grains, and obvious hole is arranged.Behind oxygenation, find out the figure, the skin membrane densification, recessed " usur hole " filled and led up, forms big crystal grain and covered by tiny crystal grain before oxygenation, and most hole is filled up by small grains, and the surface is comparatively level and smooth.
The B water-cooling wall
Water-cooling wall tubing inner surface is analyzed result who draws such as Figure of description 9, Figure 10, Figure 11, shown in Figure 12 with ESEM.
The water screen tube sample inwall epithelium situation of unit AVT-O operation after four months checked.Be depicted as before the water screen tube sample oxygenation and scanning picture during 300 times of the amplification of oxygenation after four months as Figure of description 9,10, as can be seen from Figure, the economizer tube sample inner surface particle diameter before going into operation is thicker, and is loose, and hole is arranged, and out-of-flatness.And the crystal grain that the economizer tube inside pipe wall under the operation of AVT-O operating mode forms is more tiny, even, does not have hole.
When Figure of description 11,12 saw that water screen tube inner surface state is amplified to 1000 times, skin membrane had obviously recessed " usur hole " before the oxygenation, and skin membrane loosens, and crystal grain is bigger, and the surface does not have small grains, and obvious hole is arranged.Behind oxygenation, find out the figure, the skin membrane densification, recessed " usur hole " filled and led up, forms big crystal grain and covered by tiny crystal grain before oxygenation, and most hole is filled up by small grains, and the surface is comparatively level and smooth.
Conclusion 2:
Above-mentioned analysis result is consistent with the conclusion that the X-ray diffraction analysis records.The epithelium that therrmodynamic system economizer under the reproducibility operating mode, the metallic interior surface of water-cooling wall form is more loose, and hole is arranged, and recessed " usur hole " arranged, and is the big Fe of particle; And under the AVT-O operating mode, along with the increase of oxygenation time is oxidized to the less Fe of crystal grain gradually
2O
3, after 4 months, that its pipe sample inner surface forms is the Fe of one deck smoother densification in the operation of AVT-O operating mode
2O
3Epithelium.
Four, experiment conclusion
Present embodiment has proved that the directly air cooled steam drum boiler unit gives water treatment after adopting the AVT-0 mode, has remarkable advantage:
A. form fine and close double-deck oxide-film, suppressed the mobile accelerated corrosion of therrmodynamic system;
B. the condensate water precision processing cycle of operation prolongs, and has saved a large amount of operating costs;
C. stop to add carcinogenic substance-hydrazine, reduced ammonia and added dose, help environmental protection and health;
D. indirect benefit shows as and can improve the unit availability, reduces operating cost.
Claims (4)
1, a kind of directly air cooled steam drum boiler unit feedwater treatment method, fuel is in the boiler internal combustion, stove water is heated boiling and produces high temperature and high pressure steam, afterwards driving steam turbine rotates and mechanical energy is converted into electric energy output, high temperature and high pressure steam after the acting is admitted to air cooling tower immediately, in air cooling tower, carry out direct heat transfer with the cooling air of sending into by axial flow blower, the condensate water that generates flows into condensate tank, it is characterized in that the condensate water that is flowed out by condensate tank directly enters boiler after adding ammonia under the oxygen-eliminating device oxygen discharging door closing state, the hydrogen conductance that wherein feeds water is controlled at below the 0.2 μ S/cm.
2, directly air cooled steam drum boiler unit feedwater treatment method according to claim 1 is characterized in that unit feedwater hydrogen conductance remains on when 0.2 μ S/cm is above to be moved continuously, opens the oxygen discharging door of oxygen-eliminating device.
3, directly air cooled steam drum boiler unit feedwater treatment method according to claim 1 and 2 is characterized in that adopting in the whole service processing procedure industrial on-line oxidation reduction potential instrument to feed water and stove water condition on-line monitoring and adjusting control.
4, directly air cooled steam drum boiler unit feedwater treatment method according to claim 1 and 2 is characterized in that stove hydromining hydro-oxidation sodium processing mode.
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| CN101880092B (en) * | 2010-05-27 | 2012-07-04 | 江苏省电力试验研究院有限公司 | Intrinsically-safe water-feeding and oxygen-adding treatment method of once-through boiler |
| CN102070254B (en) * | 2010-12-17 | 2012-07-11 | 江苏方天电力技术有限公司 | Essence-safe boiler feedwater oxygenation processing method |
| CN102288064B (en) * | 2011-06-17 | 2013-06-12 | 河北省电力建设调整试验所 | Protection method for joint stop of air cooling island and unit |
| CN103159347B (en) * | 2013-03-28 | 2016-04-06 | 鞍钢股份有限公司 | Method for quickly eliminating acid phosphate hiding of coke dry quenching waste heat boiler |
| CN103553198B (en) * | 2013-11-06 | 2015-07-08 | 马祝平 | Treatment process for adding strong base into power station boiler feed water |
| CN104310562A (en) * | 2014-09-30 | 2015-01-28 | 国网上海市电力公司 | Subcritical drum boiler water treatment method |
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