CN107844863A - A kind of design method of supercritical power station boiler superheater tube Dow Chemical cleaning program - Google Patents
A kind of design method of supercritical power station boiler superheater tube Dow Chemical cleaning program Download PDFInfo
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- CN107844863A CN107844863A CN201711127658.9A CN201711127658A CN107844863A CN 107844863 A CN107844863 A CN 107844863A CN 201711127658 A CN201711127658 A CN 201711127658A CN 107844863 A CN107844863 A CN 107844863A
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- 238000000034 method Methods 0.000 title claims abstract description 35
- 239000000126 substance Substances 0.000 title claims abstract description 18
- 238000013461 design Methods 0.000 title claims abstract description 8
- 238000005554 pickling Methods 0.000 claims abstract description 58
- 238000006243 chemical reaction Methods 0.000 claims abstract description 51
- 239000002253 acid Substances 0.000 claims abstract description 42
- 230000003068 static effect Effects 0.000 claims abstract description 8
- 238000012360 testing method Methods 0.000 claims abstract description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 87
- 239000010410 layer Substances 0.000 claims description 15
- 150000003839 salts Chemical class 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- 239000013598 vector Substances 0.000 claims description 5
- 239000002356 single layer Substances 0.000 claims description 4
- 238000007476 Maximum Likelihood Methods 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 238000010025 steaming Methods 0.000 claims description 2
- 238000004140 cleaning Methods 0.000 abstract description 10
- 238000013459 approach Methods 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 235000011114 ammonium hydroxide Nutrition 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 4
- 230000036632 reaction speed Effects 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000002932 luster Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229960004011 methenamine Drugs 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000013618 particulate matter Substances 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 241000208340 Araliaceae Species 0.000 description 1
- 235000005035 Panax pseudoginseng ssp. pseudoginseng Nutrition 0.000 description 1
- 235000003140 Panax quinquefolius Nutrition 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005315 distribution function Methods 0.000 description 1
- 229940056319 ferrosoferric oxide Drugs 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
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Abstract
The present invention provides a kind of design method of supercritical power station boiler superheater tube Dow Chemical cleaning program, including：It is determined that the i.e. mathematical modeling of oxide scale growth；Static test is carried out under different temperatures and concentration, determines the reacting dose of oxide skin and acid solution in the time required for acid solution completely reaction, unit interval unit area, determines the chemical reaction velocity of acid solution under different temperatures and concentration；The booster probability of superheater pipeline is predicted for the operation conditions of superheater pipeline, at the time of the booster determine the probability superheater pipeline based on superheater pipeline starts pickling；The theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant；The configuration of acid solution is carried out, so far determines supercritical power station boiler superheater tube Dow Chemical cleaning program.The present invention provides new approaches for the cleaning of power plant's superheater pipeline, chooses the Best Times that pipeline starts pickling, strengthens the run time of superheater pipeline, reduces economic loss caused by pipeline burst.
Description
Technical field
The invention belongs to process control technology field, specifically a kind of supercritical power station boiler superheater tube Dow Chemical cleaning
The design method of scheme.
Background technology
The working medium in thermal power plant is water, and under normal conditions, the heated temperature of water reaches the saturation temperature under setting pressure
When spending, phase transformation will be produced, water starts to become gaseous state by liquid, and when steam pressure reaches 22.129MPa, water adds at this pressure
When heat is to 374.15 DEG C, all vaporized, effect of the superheater in the working link of power plant is mainly taken out in saturated vapor
Moisture, protect steam turbine, the method mainly overheated allows steam drying.During this, due to high inside superheater pipeline
Temperature, the steam ambient of high pressure, metal inner surface can be warm herein at 571 DEG C with steam catalytic oxidation, the running temperature of superheater steam
Under degree, oxygen and superheater metal inner surface in air combine, and generate oxide-film, and carry out oxide-film over time is divided into three layers,
FeO-Fe is inwardly followed successively by by superheater pipeline metallic matrix always3O4-Fe2O3, it is in ferroso-ferric oxide and three oxidations of outer layer
Two ferriferous oxide compact structures, chemical property is stable, the ferrous oxide short texture of internal layer, when the temperature of superheater pipeline occurs
During acute variation, because pipeline matrix is different with the thermal stress of ferriferous oxide, oxide-film can rupture, and steam passes through oxide skin
Crack penetrates into metallic matrix and further aoxidized, and has persecuted the resistance to overturning of oxide skin, and oxide-film is easy to come off, and in pipeline
It is interior accumulative, the blocking of pipeline is caused, further causes the generation of pipeline burst problem.
The means of the oxide skin of power plant's processing at present mainly occur to be shut down after booster in pipeline, and booster part is managed
Road carries out cutting replacing, and such station boiler is inestimable to economic loss directly perceived caused by maintenance from booster to shutting down again, real
The oxide skin accumulation problem of booster pipeline is solve only on border, is not taken measures for other pipelines, the next booster such as simply
Cutting replacing is carried out during generation again, processing method is relatively rough.
The content of the invention
For the deficiency of existing oxide skin treatment technology, the present invention proposes a kind of supercritical power station boiler superheater pipeline
Learn the design method of cleaning program.
Technical solution of the present invention is as follows：
A kind of design method of supercritical power station boiler superheater tube Dow Chemical cleaning program, including：
Determine superheater the pipeline run time of superheater pipeline and corresponding oxidation under the condition of work of declared working condition
The mathematical modeling of the relation curve of skin thickness, i.e. oxide scale growth；
Static test is carried out under different temperatures and concentration, determine time completely required for reaction of oxide skin and acid solution,
The reacting dose of acid solution in unit interval unit area, determine the chemical reaction velocity of acid solution under different temperatures and concentration；
The booster probability of superheater pipeline, the booster based on superheater pipeline are predicted for the operation conditions of superheater pipeline
At the time of determine the probability superheater pipeline starts pickling；
The theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant；
Based on the theoretical time of oxide skin pickling, the configuration of acid solution is carried out, so far determines that supercritical power station boiler overheats
Device pipeline Chemical cleaning scheme.
The method for building up of the mathematical modeling of the oxide scale growth is as follows：
The historical data of superheater pipeline under the condition of work of declared working condition is obtained, during including superheater conduit running
Vapor (steam) temperature, pressure, t times scale thickness, run time；
Historical data recurrence is handled, fits the operation of the superheater pipeline in the case where vapor (steam) temperature, pressure are certain
Time and the relation curve of corresponding scale thickness, obtain the mathematical modeling of oxide scale growth.
The mathematical modeling of the growth of the oxide skin is：Wherein, δ is the thickness of t time oxide skins, and A is undetermined
Coefficient, n values in [1,2], during n=1, the growth curve of oxide skin is linear, and during n=2, the growth curve of oxide skin is in throwing
Thing wire shaped, the historical data according to superheater pipeline carry out undetermined coefficient A estimation.
The chemical reaction velocity for determining hydrochloric acid under different temperatures and concentration, specific method are：
The different acid solution of compound concentration respectively, different temperatures is set, area identical oxide skin is respectively cut and carries out static state
Experiment, time of the record oxide skin required for acid solution completely reaction；
According to the time required for oxide skin and acid solution reaction completely, the reaction of acid solution in unit interval unit area is determined
Amount, and then determine the chemical reaction velocity of acid solution under different temperatures and concentration.
The operation conditions for superheater pipeline predicts the booster probability of superheater pipeline, and specific method is：
Extract historical data related to booster failure in superheater pipeline historical data；
It is general based on historical data related to booster failure in superheater pipeline historical data, training superheater pipeline burst
The risk forecast model of rate；
After given state characteristic vector of the superheater conduit running to certain moment, the booster for calculating superheater pipeline is general
Rate functional value.
At the time of the booster determine the probability superheater pipeline based on superheater pipeline starts pickling, specifically by booster
At the time of at the time of probability function value reaches the setting upper limit as pickling is started.
The method for building up of the risk forecast model of the superheater pipeline burst probability is as follows：
Define the risk forecast model of superheater pipeline burst probability；Weibull distribution is selected as substrate booster risk letter
Number, obtains the risk forecast model of final superheater pipeline burst probability；Superheater pipeline is carried out using maximum likelihood function method
The parameter Estimation of the risk forecast model of booster probability, for the historical data related to booster failure of N bar superheater pipelines,
Determine the likelihood function of the risk forecast model of superheater pipeline burst probability；Likelihood function is carried out based on DFP methods very big
The solution of value.
It is described oxide skin pickling is determined in the case where chemical reaction velocity is constant the method for theoretical time be：
The concentration of acid solution and the temperature of pickling environment are configured according to pickling, determines the chemical reaction velocity of acid solution；
Calculate time of the mono-layer oxidized skin completely required for reaction in pipeline unit area；
Calculate time of the three layers of oxide skin completely required for reaction in pipeline unit area；
Calculate the hydrochloric acid content of three kinds of oxides consumption contained by three layers of oxide skin；
Calculate the salt acid consumption in inner-walls of duct unit area；
The theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant, i.e. contained by three layers of oxide skin
Salt acid consumption in the hydrochloric acid content sum divided by inner-walls of duct unit area of three kinds of oxide consumption.
Beneficial effect：
The booster probability of superheater pipeline, the booster based on superheater pipeline are predicted for the operation conditions of superheater pipeline
At the time of determine the probability superheater pipeline starts pickling；The concentration of hydrochloric acid and the temperature of pickling environment are configured according to pickling, really
Determine the chemical reaction velocity of hydrochloric acid, the mathematical modeling based on oxide scale growth determines to start the thickness of oxide skin at the time of pickling,
And the weight of oxide skin is calculated, the theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant.Based on oxygen
Change the theoretical time of skin pickling, carry out the configuration of acid solution, determine supercritical power station boiler superheater tube Dow Chemical cleaning program.
The present invention provides new approaches for the cleaning of power plant's superheater pipeline, chooses the Best Times that pipeline starts pickling, and power plant chooses
Suitable time application is shut down, and carries out pipeline oxidization skin Chemical cleaning.Reduce the booster probability of superheater, strengthen superheater tube
The run time in road, economic loss caused by reducing pipeline burst, lift the economic benefit of power plant.
Brief description of the drawings
Fig. 1 is pickler schematic diagram, wherein 1 descaling bath, 2 thermostat water baths, 3 rinsing bowls, 4 magnetic drive pumps, 5 Electromagnetic Flows
Pickling pipeline, 7 exhausted bath box are treated in meter, 6；
Fig. 2 is the chemical reaction velocity of the hydrochloric acid at room temperature in the specific embodiment of the invention with concentration curve；
Fig. 3 is the relation of the absolute temperature in the specific embodiment of the invention and hydrochloric acid chemical reaction velocity.
Embodiment
The specific embodiment of the invention is described in detail below in conjunction with the accompanying drawings.
For recyclable pickling platform in present embodiment, pickler as shown in Figure 1, mainly include：Descaling bath 1,
Thermostat water bath 2, rinsing bowl 3, magnetic drive pump 4, electromagnetic flowmeter 5, pickling pipeline 6, exhausted bath box 7 are treated, mainly pass through control valve
Aperture carry out the control of uninterrupted, thermostat water bath 2 carries out the setting of reaction temperature, acid solution used by present embodiment
For hydrochloric acid, reaction temperature controls at room temperature, 30 degrees Celsius of temperature.
Present embodiment provides a kind of design method of supercritical power station boiler superheater tube Dow Chemical cleaning program, bag
Include：
Step 1：Determine superheater pipeline under the condition of work of declared working condition the run time of superheater pipeline with it is corresponding
Scale thickness relation curve, i.e. oxide scale growth mathematical modeling.
Step 1.1：The historical data X=[T, P, δ, t] of superheater pipeline under the condition of work of declared working condition is obtained, wherein
Vapor (steam) temperature T, pressure P, t time scale thickness δ, run time t during including superheater conduit running.
Step 1.2：Historical data recurrence is handled, fits the superheater in the case where vapor (steam) temperature T, pressure P are certain
The run time of pipeline and the relation curve of corresponding scale thickness, obtain the mathematical modeling of oxide scale growth.
Growth of the oxide skin in superheater pipeline is divided into two stages：The growth curve of first stage oxide skin is in line
Property；Second stage is because the heat-blocking action of oxide skin, the growth curve of oxide skin tend towards stability, parabolically shape.Therefore, exist
Under the condition of work of declared working condition, the mathematical modeling of the growth of oxide skin is superheater pipeline：Wherein, when δ is t
Between oxide skin thickness, A is undetermined coefficient, n values in [1,2], and during n=1, the growth curve of oxide skin is linear, n=2
When, the growth curve of oxide skin parabolically shape, historical data during selection according to superheater pipeline carries out undetermined coefficient A's
Estimate, n=1.62, A=136.2 in present embodiment.
Step 2：Static test is carried out under different temperatures and concentration, is determined required for the reaction completely of oxide skin and hydrochloric acid
The reacting dose of hydrochloric acid on time, unit interval unit area, determine the chemical reaction velocity of hydrochloric acid under different temperatures and concentration.
Step 2.1：The different hydrochloric acid of compound concentration respectively, different temperatures is set in thermostat water bath, face is respectively cut
Product identical oxide skin carries out static test, time of the record oxide skin required for hydrochloric acid completely reaction.
In present embodiment, respectively 10g/L, 20g/L, 50g/L, 100g/L, 150g/L dilute hydrochloric acid solution, in constant temperature
Temperature is set in water-bath from 20~40 degrees Celsius, the oxide skin that area is 1 square centimeter is respectively cut and carries out static state
Experiment, time of the record oxide skin required for hydrochloric acid completely reaction.
Step 2.2：According to the time required for oxide skin and hydrochloric acid reaction completely, salt in unit interval unit area is determined
The reacting dose of acid, and then determine the chemical reaction velocity of hydrochloric acid under different temperatures and concentration.The chemical reaction speed of hydrochloric acid at room temperature
Degree is as shown in Figure 2 with concentration curve.The relation of absolute temperature and hydrochloric acid chemical reaction velocity is as shown in Figure 3.
Step 3：The booster probability of superheater pipeline is predicted for the operation conditions of superheater pipeline, based on superheater pipeline
Booster determine the probability superheater pipeline at the time of start pickling.
Step 3.1：Historical data related to booster failure in superheater pipeline historical data is extracted, establishes following number
According to collection：
DataSet (i)=(ti, Xi, δi) i=1,2 ..., N；
Wherein, the running state data X of i-th pipelinei=(xI, 1, xI, 2…xI, p-1, xI, p), xI, pRepresent superheater i-th
P-th of state characteristic vector of root pipeline, the p=4 in present embodiment, i.e., the running state data of i-th pipeline include steaming
This four state characteristic vectors of stripping temperature, pipe wall temperature, run time, rate of temperature change.δiIt is random right censorship data
Instruction explanation, δ=1 represents that booster event occurs for superheater pipeline in observation time, and δ=0 does not occur quick-fried in observation time
Run affairs part, be Right censored data.tiThe time of booster event occurs for i-th pipeline represented.N is superheater pipeline in data set
Quantity.
Step 3.2：Based on historical data related to booster failure in superheater pipeline historical data, superheater tube is trained
The risk forecast model of road booster probability；
Step 3.2.1：Define the risk forecast model of superheater pipeline burst probability：
h(ti, Xi)=h0(ti)exp(xI, 1β1+xI, 2β2+…+xI, pβp)
Wherein, h (ti, Xi) it is that operation conditions is XiSuperheater pipeline in moment ti(t during startingi=0) booster occurs
Probability, β1, β2…βp-1, βpThe parameter for size that to be different operation conditions influence on superheater pipeline burst, referred to as regression coefficient,
The size of booster probability is influenceed, using historical data related to booster failure in superheater pipeline historical data estimate
Go out.h0(ti) it is substrate booster risk function.
Step 3.2.2：Select Weibull distribution that it is general to obtain final superheater pipeline burst as substrate booster risk function
The risk forecast model of rate；
Substrate booster risk function：
Wherein：η ＞ 0 are scale parameters, and γ ＞ 0 are form parameters, by h0(ti) bring h (t intoi, Xi)；
Obtain the risk forecast model of final superheater pipeline burst probability：
Step 3.2.3：The ginseng of the risk forecast model of superheater pipeline burst probability is carried out using maximum likelihood function method
Number estimation, for the historical data related to booster failure of N bar superheater pipelines, determine the wind of superheater pipeline burst probability
The likelihood function of dangerous forecast model is：
Wherein, Si(ti, Xi) it is Reliability Function, derived by Cumulative Distribution Function and obtained：
The both sides of Reliability Function are taken the logarithm simultaneously, can be obtained：
Thus, the problem of parameter Estimation being converted to function lnL (γ, η, β) maximizing.
Step 3.2.4：The solution of maximum is carried out to lnL (γ, η, β) based on DFP methods.
DFP methods are the optimized algorithms named with Davidon, Fletcher, Powell.
Step 3.2.4.1：Determine object function f (γ, η, β)=lnL (γ, η, β), object function f (γ, η, β) ladder
Spend for g (γ, η, β).
Step 3.2.4.2：One group of γ is randomly choosed, η, β are as selected iteration initial point I0=(γ, η, β), and calculate
Initial object function f0=f (I0), initial gradient g0=g (I0)；Setting terminates limit and maximum iteration n '；
Step 3.2.4.3：H is setoInitial value be unit battle array, setting initial search direction is p0=-g0, iterations k
=0.
Step 3.2.4.4：Linear search is done along initial search direction, obtains k+1 iteration point Ik+1=ls (Ik, pk),
New iteration initial value is obtained, calculates f on this basisk+1=f (Ik+1), gk+1=g (Ik+1), pkIt is searching for k-th iteration point
Suo Fangxiang, IkIt is k iteration point.
Step 3.2.4.5：Judge whether current iteration meets to terminate limit, satisfaction then stops iteration, obtains current iteration point
Corresponding estimates of parametersPerform step 3.3；Otherwise step 3.2.4.6 is continued；
Step 3.2.4.6：If k=n ', set I0=Ik+1, f0=fk+1, g0=gk+1, previous step 3.2.4.4 is gone to, it is no
Then perform step 3.2.4.7；
Step 3.2.4.7：Calculate the gradient difference y between k+1 iteration point and k iteration pointk, k+1 iteration point and k are individual
Difference s between iteration pointk, the estimation H of the gloomy inverse of a matrix of Second Order Sea corresponding to k+1 iteration pointk+1：
yk=gk+1-gk sk=Ik+1-Ik
pk+1=-Hk+1gk+1
K=k+1 is set, goes to step 3.2.4.4, continues linear search.
Step 3.3：In given superheater conduit running to tiState feature vector, X (the t at momenti) after, calculate superheater
The booster probability function value of pipeline：
So it is known that the general of booster occurs for a certain moment pipeline for every superheater pipeline real time data based on power plant
Rate.
Step 3.4：At the time of booster determine the probability superheater pipeline based on superheater pipeline starts pickling：Booster probability
At the time of functional value reaches at the time of setting the upper limit (90%) to start pickling, now Field Force, which applies shutting down, carries out pickling.
Step 4：The concentration of hydrochloric acid and the temperature of pickling environment are configured according to pickling, determines the chemical reaction speed of hydrochloric acid
Degree, the mathematical modeling based on oxide scale growth determines to start the thickness of oxide skin at the time of pickling, and calculates the weight of oxide skin,
The theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant.
Step 4.1：The concentration of hydrochloric acid and the temperature of pickling environment are configured according to pickling, determines the chemical reaction speed of hydrochloric acid
Degree；
So that configuration concentration is 300g/L hydrochloric acid as an example, the chemical reaction velocity of the hydrochloric acid determined at room temperatureC thereinHCLThe concentration of hydrochloric acid is represented, T represents acid
Wash the temperature of environment.
Step 4.2：Time completely reaction required for of mono-layer oxidized skin is calculated in pipeline unit area in theory；
Assuming that the specification for taking length to be one meter is the pipeline of 55*4.5 millimeters, the pipe according to determined by oxide scale growth model
Road inner wall oxide skin thickness is 300 microns, on the premise of oxide skin is uniformly distributed, calculates the oxide skin weight inside pipeline
mFeoFor：
Wherein, ρ is ferrous oxide density, and r is the internal diameter of pipeline, and δ is the thickness for representing t time oxide skins, and l is pipeline
Length
The now consumption m of hydrochloric acidHClFor：
The reaction speed of hydrochloric acid is in inner-walls of duct unit area：
ΔmHCl=k2 π rnΔ l=0.867g/s
Time of the mono-layer oxidized skin completely required for reaction in pipeline unit area in theory：
Step 4.3：Calculate time of the three layers of oxide skin completely required for reaction in pipeline unit area；
Oxide skin is outwards divided into three layers from metallic matrix, is respectively：FeO-Fe2O4-Fe2O3, thickness ratio is designated as 100:
Under the conditions of 10: 1 is such a, time of the three layers of oxide skin completely required for reaction is calculated again respectively：
Step 4.4：Calculate the hydrochloric acid content of three kinds of oxides consumption contained by three layers of oxide skin；
Under the dissolution of hydrochloric acid, the hydrochloric acid content of three kinds of oxides consumption contained by three layers of oxide skin is calculated respectively such as
Under：
Step 4.5：Calculate the salt acid consumption in inner-walls of duct unit area：
Wherein, k is the chemical reaction velocity of hydrochloric acid, rnIt is the internal diameter of pipeline.
Step 4.6：The theoretical time of oxide skin pickling, i.e., three layers oxidation are determined in the case where chemical reaction velocity is constant
Salt acid consumption in the hydrochloric acid content sum divided by inner-walls of duct unit area of three kinds of oxides consumption contained by skin：
Step 5：Based on the theoretical time of oxide skin pickling, the configuration of hydrochloric acid is carried out, so far determines overcritical power station pot
Stove superheater tube Dow Chemical cleaning program, including at the time of start pickling, the theoretical time of oxide skin pickling and hydrochloric acid it is dense
Degree and consumption.
Chemical cleaning is carried out according to the supercritical power station boiler superheater tube Dow Chemical cleaning program of determination, use is commercially available
20% 60g/L hydrochloric acid is configured, and under normal temperature, the density of 20% hydrochloric acid is 1.098g/cm3, carry out configuration acid during pickling
Washing lotion 20L, it is necessary to 20% watery hydrochloric acid 5.46L, clear water 14.56L, add corrosion inhibiter methenamine 0.2kg, configuration obtain pickling
Solution.
| 20% hydrochloric acid | Clear water | Methenamine |
| 5.46L | 14.56L | 0.2kg |
It it is now 30 degrees Celsius according to the temperature of pickling environment, the theoretical time for calculating oxide skin pickling is 84.48 minutes.
The outlet of the pipeline access acid solution of pickling will be treated, the temperature of thermostat water bath is set, opens valve, carry out acid solution
Circulation flushing, on the basis of the theoretical time of oxide skin pickling, reserve 20% time, that is, 67.584 minutes check pipe
The pickling situation in road, when pipeline interior surface is smooth rustless, presentation metallic luster is as qualified.
Check the effect of Chemical cleaning：
First, wash：Acid solution remaining in pipeline is cleaned up, prevents acid solution from remaining further corrosion metallic matrix；
Secondly, passivation：Pipeline after pickling is protected, passivating dip concrete configuration：
The configuration selection natrium nitrosum and ammoniacal liquor of passivating dip, need to ensure that the percentage of natrium nitrosum is more than 1 during configuration,
Alkalescence environment is in, the configuration of alkaline environment is carried out with 25% ammoniacal liquor, chooses 0.5kg natrium nitrosums, add 20L clear water
In, stir, add ammoniacal liquor on this basis, while adding ammoniacal liquor, while measuring the pH value of passivating solution, pass through the tune of ammoniacal liquor
Section, determines the PH of passivating solution between 9-10.
| Natrium nitrosum | Clear water | Ammoniacal liquor | PH |
| 0.5kg | 20L | 25% | 9 |
Then, wash again：Passivating dip in purging line, clear water pipeline is accessed, clean remnants passivating dip, water
Wash half an hour time.
After specifically checking that pickling pipeline is qualified, access clear water is cleaned.Half an hour time.
Finally, dry：In pipeline after a series of processes such as acid wash passivation water flushing, to dry up immediately, gas is adopted
With dry compressed air, drying.
The embodiment that Chemical cleaning is carried out using the inventive method is as follows：
Embodiment 1：
Viewing is cut to certain pipe samples to carry out, observes the oxide skin situation of inner-walls of duct, and inner-walls of duct corrodes, and surface is thick
It is rough, there is distribution of particles not of uniform size, nigrescence carries kermesinus, and oxide skin distribution is more uniform.Carried out using 6% hydrochloric acid solution
Pickling, now theoretic pickling time is 84 minutes, when reality controls, pickling time 60 minutes, and after cleaning, inner surface wall light
Sliding, clear metallic luster is presented in the particulate matter not being randomly distributed, inner surface, overpickling situation does not occur, during hydrochloric acid
Between control on just.
Embodiment 2：
The cutting viewing of the sample of certain pipeline is carried out, observes the oxide skin situation of inner-walls of duct, inner surface wall furvous, slightly
Corrosion, table wall are evenly distributed without distribution of particles, oxide skin, same to control pickling time 60 minutes, after cleaning, inner surface wall light
Sliding, clear metallic luster is presented in the particulate matter not being randomly distributed, inner surface, overpickling situation does not occur.
Claims (8)
- A kind of 1. design method of supercritical power station boiler superheater tube Dow Chemical cleaning program, it is characterised in that including：Determine superheater the pipeline run time of superheater pipeline and corresponding oxidation skin depth under the condition of work of declared working condition The mathematical modeling of the relation curve of degree, i.e. oxide scale growth；Static test is carried out under different temperatures and concentration, determines oxide skin and the time required for acid solution completely reaction, unit The reacting dose of acid solution on chronomere's area, determine the chemical reaction velocity of acid solution under different temperatures and concentration；The booster probability of superheater pipeline, the booster probability based on superheater pipeline are predicted for the operation conditions of superheater pipeline At the time of determining that superheater pipeline starts pickling；The theoretical time of oxide skin pickling is determined in the case where chemical reaction velocity is constant；Based on the theoretical time of oxide skin pickling, the configuration of acid solution is carried out, so far determines supercritical power station boiler superheater tube Dow Chemical cleaning program.
- 2. according to the method for claim 1, it is characterised in that the method for building up of the mathematical modeling of the oxide scale growth is such as Under：The historical data of superheater pipeline under the condition of work of declared working condition is obtained, steaming during including superheater conduit running Stripping temperature, pressure, t times scale thickness, run time；Historical data recurrence is handled, fits the run time of the superheater pipeline in the case where vapor (steam) temperature, pressure are certain With the relation curve of corresponding scale thickness, the mathematical modeling of oxide scale growth is obtained.
- 3. method according to claim 1 or 2, it is characterised in that the mathematical modeling of the growth of the oxide skin is：Wherein, δ is the thickness of t time oxide skins, and A is undetermined coefficient, n values in [1,2], during n=1, the life of oxide skin Long curve is linear, and during n=2, parabolically shape, the historical data according to superheater pipeline are carried out the growth curve of oxide skin Undetermined coefficient A estimation.
- 4. according to the method for claim 1, it is characterised in that the chemistry for determining hydrochloric acid under different temperatures and concentration is instead Speed is answered, specific method is：The different acid solution of compound concentration respectively, different temperatures is set, area identical oxide skin is respectively cut and carries out static test, Record time of the oxide skin required for acid solution completely reaction；The time required according to the reaction completely of oxide skin and acid solution, the reacting dose of acid solution in unit interval unit area is determined, And then determine the chemical reaction velocity of acid solution under different temperatures and concentration.
- 5. according to the method for claim 1, it is characterised in that the operation conditions for superheater pipeline predicts overheat The booster probability of device pipeline, specific method are：Extract historical data related to booster failure in superheater pipeline historical data；Based on historical data related to booster failure in superheater pipeline historical data, superheater pipeline burst probability is trained Risk forecast model；After given state characteristic vector of the superheater conduit running to certain moment, the booster probability letter of superheater pipeline is calculated Numerical value.
- 6. according to the method for claim 1, it is characterised in that the booster determine the probability overheat based on superheater pipeline At the time of device pipeline starts pickling, specifically using booster probability function value reach setting the upper limit at the time of as start pickling when Carve.
- 7. according to the method for claim 5, it is characterised in that the risk forecast model of the superheater pipeline burst probability Method for building up it is as follows：Define the risk forecast model of superheater pipeline burst probability；Weibull distribution is selected as substrate booster risk function, Obtain the risk forecast model of final superheater pipeline burst probability；Superheater pipeline burst is carried out using maximum likelihood function method The parameter Estimation of the risk forecast model of probability, for the historical data related to booster failure of N bar superheater pipelines, it is determined that The likelihood function of the risk forecast model of superheater pipeline burst probability；Maximum is carried out to likelihood function based on DFP methods Solve.
- 8. according to the method for claim 1, it is characterised in that described to determine oxygen in the case where chemical reaction velocity is constant Changing the method for the theoretical time of skin pickling is：The concentration of acid solution and the temperature of pickling environment are configured according to pickling, determines the chemical reaction velocity of acid solution；Calculate time of the mono-layer oxidized skin completely required for reaction in pipeline unit area；Calculate time of the three layers of oxide skin completely required for reaction in pipeline unit area；Calculate the hydrochloric acid content of three kinds of oxides consumption contained by three layers of oxide skin；Calculate the salt acid consumption in inner-walls of duct unit area；The theoretical time of oxide skin pickling, i.e. three kinds contained by three layers of oxide skin are determined in the case where chemical reaction velocity is constant Salt acid consumption in the hydrochloric acid content sum divided by inner-walls of duct unit area of oxide consumption.
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| PCT/CN2018/087695 WO2019095658A1 (en) | 2017-11-15 | 2018-05-21 | Design method of chemical cleaning scheme for superheater pipe of supercritical power station boiler |
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| WO2019095658A1 (en) * | 2017-11-15 | 2019-05-23 | 东北大学 | Design method of chemical cleaning scheme for superheater pipe of supercritical power station boiler |
| CN111893424A (en) * | 2020-06-29 | 2020-11-06 | 武汉钢铁有限公司 | Plate blank surface iron scale heating control method based on hot-conveying and hot-charging process |
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| US20090246064A1 (en) * | 2006-08-23 | 2009-10-01 | Nkk Tubes | Austenitic Stainless Steel Tube for Boiler with Excellent Resistance to High Temperature Steam Oxidation |
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| WO2019095658A1 (en) | 2019-05-23 |
| CN107844863B (en) | 2019-12-31 |
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