CN103629657B - Method and device for monitoring high-temperature oxide scales of generator set - Google Patents
Method and device for monitoring high-temperature oxide scales of generator set Download PDFInfo
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 59
- 239000001257 hydrogen Substances 0.000 claims abstract description 146
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 146
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 134
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 85
- 238000005260 corrosion Methods 0.000 claims abstract description 52
- 230000007797 corrosion Effects 0.000 claims abstract description 49
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 44
- 230000008569 process Effects 0.000 claims abstract description 24
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- 150000002431 hydrogen Chemical class 0.000 claims abstract description 13
- 230000003647 oxidation Effects 0.000 claims description 31
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 229910052760 oxygen Inorganic materials 0.000 claims description 20
- 238000010977 unit operation Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 7
- 230000007423 decrease Effects 0.000 claims description 4
- 238000011010 flushing procedure Methods 0.000 claims description 3
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Abstract
The invention provides a method and device for monitoring high-temperature oxide scales of a generator set. The method includes the steps of online monitoring the dissolved hydrogen content in an inlet of an economizer, an outlet of a steam separator, an outlet of a superheater and an outlet of a reheater in a steam-water system in the starting and running process of the generator set in real time; monitoring generator set parameters and water working condition parameters; collecting monitoring data, conducting analysis to set up a relation among the generator set parameters, the water working condition parameters and the change of dissolved hydrogen, and tracking and monitoring the corrosion and oxidization condition of the generator set in real time. By means of the method and the device, the dissolved hydrogen content in a vapor system of the running generator set can be online monitored in real time, the relation of the dissolved hydrogen change caused by operation of the generator set is set up, the corrosion and oxidization condition of the generator set is tracked and monitored in real time, operation in the starting and stopping process of the generator set and the generator set running working condition are optimized and adjusted according to data analysis of a corrosion and oxidization monitoring system, and corrosion and oxidization of the generator set are reduced to the maximum extent.
Description
Technical field
The invention relates to a kind of method and device of monitoring generating set high temperature scale situation.
Background technology
Along with the raising of vapor (steam) temperature and pressure, the efficiency of boiler is increasing substantially, net coal consumption rate declines, but also encounter some technical barriers while improving steam parameter, the resistance to high temperature corrosion of the mainly performance issue of metal material under high temperature, high pressure, especially material and pyrogenic steam oxidation ability.Under the effect of high-temperature steam, the oxidation of metal wall is inevitable, thus generates one deck oxide skin in metal surface.These corrosion and oxidation product can pollute water and steam quality, enter condensate system, become the deposit at the easy fouling position of heat power equipment, in addition, peeling off after oxide skin increases fast can be caused plugging or be caused overtemperature tube burst leakage accident, may cause the solid particle erosion to turbine inlet flow passage component and infringement turbine blade simultaneously.
On-line monitoring is carried out to therrmodynamic system corrosion and oxidizing process, understand and grasp Metal Materials At High Temperature corrosion and the rule be oxidized, use the knowledge of this respect to reduce or to suppress high temperature corrosion and oxidation reaction, and associated technical parameters is optimized, to the safe and stable operation of unit, there is larger directive significance.
Ultrasonic Detection Method measures the common method of boiler tubing internal oxidition skin thickness at present.Its principle carries out thickness measure according to Ultrasonic Pulse-Echo principle, when the ultrasonic pulse launched when popping one's head in arrives material interface by testee, pulse is reflected back toward the thickness that the time of propagating in the material by accurately measuring ultrasonic wave of popping one's head in determines measured material, and the method commonly uses the service life for assessment of Boiler Pipe.But the precision that ultrasonic Detection Method is measured is lower, usually can not accurately measure the thickness being less than 0.2mm.For the unit of overcritical and above parameter, the high chromium content stainless steel material that its superheater, reheater adopt usually, the speed that oxide skin increases is lower, and its thickness generated in running is less than 0.2mm usually, generate thickness according to ultrasound examination oxide skin, usually bring comparatively big error.
Magnetic field detection method detects unit superheater, reheater oxide skin at present with or without the most common method peeled off, and its principle utilizes self-contained permanent magnet, and boiler high temperature pipeline produces a longitudinal magnetic field.If have oxide skin in pipe, because it shows as paramagnetism, then the magnetic line of force deforms, and corresponding change occurs ambient magnetic field strength.The coupled relation of research oxide skin and magnetic field intensity, can characterize the situation of pipe internal oxidition skin.But magnetic field detection method also has its limitation.It is that the oxide skin that raw material generates detects that the first can only be used for Austenitic stainless steel pipe material, and the sensitivity for other non-austenite tubing is low.Two is after compressor emergency shutdown cooling, then to carry out detecting by root pipe to tested test tube sample, can not realize carrying out Real-Time Monitoring to the rate of rise of oxide skin in unit operation.
Prior art document " the oxidation mechanism discussion of steam to steel surface and the application of dissolved hydrogen monitoring technology " (Liu Zhilong, Hash company, Beijing) disclose a kind of dissolved hydrogen monitoring technology, there is illustrated the thinking adopting electrochemical process monitoring dissolved hydrogen, four points (superheater outlet, boiler export, reheater 1, reheater 2) monitoring hydrogen content in steam-water circulation system, and analyze the influence factor of measurement accuracy.The measurement that the prior art also discloses hydrogen concentration change is relevant with rate of metal corrosion, and the hydrogen concentration measured in steam and feedwater can be used in reflecting the corrosion activity in stokehold and steam generator system.The document is mainly discussed the measurement meaning of dissolved hydrogen in steam, principle and method, the not metal erosion oxidation monitoring system of complete set, and, only obtain dissolved hydrogen content and can not disclose corrosion of metal and the state of oxidation exactly, therefore disclosed in the document, technology seldom has application in practice.
Summary of the invention
One object of the present invention is the method for the monitoring generating set high temperature scale situation providing a kind of improvement, real time on-line monitoring is carried out to parameters such as the dissolved hydrogen content in operating unit vapour system, unit parameter (particularly unit load), water conditions (particularly dissolved oxygen), according to monitoring result, set up the variation relation of the dissolved hydrogen that unit operations is brought, in real time to unit occur corrosion and oxidization condition carry out tracking and monitoring; And further according to the data analysis of corrosion oxidation monitoring system, adjustment is optimized to the operation in Unit Commitment process, unit operation operating mode, reduce corrosion and the oxidation of unit to greatest extent.
Another object of the present invention is to provide a kind of device for realizing above-mentioned monitoring method.
For reaching above-mentioned purpose, inventor has analyzed and researched generating set therrmodynamic system oxidation mechanism, unit in running, the moment generation of corroding along with denier in metal wall and high-temperature water vapor, and produce the dissolved hydrogen of denier.By the monitoring to system privileged site dissolved hydrogen, in conjunction with the monitoring of the monitoring to unit parameter (particularly unit load), water condition (particularly dissolved oxygen), the parameters such as dissolved hydrogen content, unit load, dissolved oxygen in Unit Steam Water system are carried out data integration, effectively can judge that whether the oxide-film that metal wall is formed is complete, and then remind professional to make correct assessment very soon to therrmodynamic system corrosion, find out corrosion place.
About the mechanism of stainless steel water steam corrosion and oxidation, Schikorr proposes, and in the steam that temperature is greater than at 450 DEG C, iron and steam react and generates tri-iron tetroxide and releasing hydrogen gas, are shown below:
3Fe＋4H
2O＝Fe
3O
4＋4H
2↑
The oxygen occurring to be oxidized with iron derives from H
2o, H
2o and O
2and H
2there is following equilibrium relation:
H
2O=H
2+1/2O
2
Therefore, the oxidisability power of steam depends on p (H
2)/p (H
2o) ratio.At 600 DEG C, the p (H balanced with FeO
2)/p (H
2o) value is about 7, and corresponding equilibrium oxygen partial pres-sure is 10
-26about atm.Under boiler actual condition, the flow of steam is very large, and the hydrogen of production is little, and hydrogen can be run away along with steam, therefore p (H
2)/p (H
2o) to, well below the numerical value of 7, impel reaction to carry out to the right, cause the continuation of iron to be oxidized.From thermodynamics analysis, the high-temperature vapor oxidation of iron is natural process, unavoidably.
The reaction rate on steam and steel surface is by dynamics Controlling, and it represents with Arrhenius formula:
P=B·e
Q/RT
P hydrogen output (mg/s), the vapor (steam) temperature (K) of T sample point, B constant, Q activation energy, R gas constant.
From theory, by the monitoring of monitoring system product hydrogen content, the oxidation rate of metal under high-temperature water vapor and the impact of complexity factor can be disclosed.But, inventor finds in practical study, dissolved hydrogen content is subject to unit parameter (such as metal temperature, unit load, flow, pressure etc., particularly unit load), water condition (such as pH value, dissolved oxygen, electrical conductivity etc., particularly dissolved oxygen) etc. the impact of factor, only obtain hydrogen content and can not accurately disclose corrosion of metal and the state of oxidation.Monitor parameters such as dissolved hydrogen content, unit parameter, water conditions in Unit Steam Water system in the present invention, become by each group data set, by real-time data monitoring analysis, the corrosion condition parsing metal material, thus Instructing manufacture runs.The unit monitored runs by certain load pattern in a whole day.Unit runs with low-down load method at night usually, runs in the morning with the peak times of power consumption in evening in high load capacity mode.The change of load causes the change of steam flow, temperature and pressure, thus result in the change that in steam, hydrogen content is complicated in time.
In the present invention, be provided with the monitoring point of at least four dissolve hydrogen concentrations in generating set boiler circuit, be respectively economizer entrance, steam-water separator outlet, superheater outlet and reheater outlet, each monitoring point is shown in Figure 1.
By the monitoring of described four monitoring point dissolve hydrogen concentrations, can than the changes of contents more comprehensively reflecting dissolved hydrogen in boiler circuit, in conjunction with unit parameter, the isoparametric monitoring of water condition, analyze the influence degree of hydrogen content by the factor such as unit parameter, water condition, and then disclose the oxidation rate of metal, assessment metal material oxidation speed, and then unit thermal parameter and water condition are optimized, reduce the speed of unit corrosion and oxidation to the full extent.
Thus on the one hand, the invention provides a kind of method of monitoring generating set high temperature scale situation, the method comprises:
The dissolved hydrogen content of economizer entrance in boiler circuit when starting generating set and in running, steam-water separator outlet, superheater outlet and reheater outlet carries out real time on-line monitoring; And monitor unit parameter, water condition parameter;
Gather Monitoring Data, analyze and set up unit parameter, relation between water condition parameter and the change of dissolved hydrogen, the corrosion occurred unit in real time and oxidization condition carry out tracking and monitoring.
According to specific embodiment of the invention scheme, the method for monitoring generating set high temperature scale situation of the present invention, wherein, described unit parameter comprises unit load.Further, described unit parameter also optionally comprises one or more parameters in metal temperature, flow, pressure.
According to specific embodiment of the invention scheme, the method for monitoring generating set high temperature scale situation of the present invention, wherein, described water condition comprises dissolved oxygen.Further, described water condition also optionally comprises one or more parameters in pH value, electrical conductivity etc.
According to specific embodiment of the invention scheme, the method for monitoring generating set high temperature scale situation of the present invention also comprises:
According to Monitoring Data and unit parameter, relationship analysis between water condition parameter and the change of dissolved hydrogen, adjustment is optimized to the operation in Unit Commitment process, unit operation operating mode, to reduce corrosion and the oxidation of unit to greatest extent.
According to specific embodiment of the invention scheme, the method of monitoring generating set high temperature scale situation of the present invention, wherein, according to anticorrosion ability before main steam, reheated steam dissolved hydrogen content Monitoring Data assessment water and steam quality and unit starting during unit starting (before during unit starting, the low Gao Kecong of main steam, reheated steam dissolved hydrogen content to a certain degree reflects water and steam quality quality and unit starting, anticorrosion ability information is fine or not).When unit starting, main steam dissolved hydrogen content is greater than 10 μ about g/kg and/or reheated steam dissolved hydrogen content when being greater than 20 μ about g/kg, and water and steam quality is not good, or the anti-corrosion protection effect between the down period before unit starting is poor.According to preferred specific embodiments of the present invention, when unit starting, main steam dissolved hydrogen content is greater than 10 μ about g/kg and/or reheated steam dissolved hydrogen content when being greater than 20 μ about g/kg, optimizes and revises as follows the operation in Unit Commitment process, unit operation operating mode:
Flushing when anti-corrosion protection measure during strengthening compressor emergency shutdown, reinforcement unit starting, and/or
Suitable raising feedwater pH value.
According to specific embodiment of the invention scheme, the method of monitoring generating set high temperature scale situation of the present invention, wherein, in unit running process, economizer entrance, steam-water separator place dissolved hydrogen content at 1 below μ g/kg, illustrate water supply system, economizer, water-cooling wall place occur corrosion less; In main steam and reheated steam, dissolved hydrogen content is at 2.0 below μ g/kg, illustrates that superheater, reheater oxide skin are more complete, peel off and crushing less, oxide skin rate of rise is slow.
According to specific embodiment of the invention scheme, the method of monitoring generating set high temperature scale situation of the present invention, wherein, when dissolved hydrogen content in main steam in unit running process and/or reheated steam is greater than 2.0 μ g/kg, the operation in Unit Commitment process, unit operation operating mode are optimized and revised as follows:
First check that Steam-water Quality has without exception, especially system pH value is with or without decline (if pH value has decline, suitably can improve feedwater pH value);
If Steam-water Quality is without exception, check the elevation rate (during unit load height, dissolved hydrogen content rises rapidly thereupon) of unit load;
Elevation rate as unit load meets normal operation, checks other unit parameter situations such as temperature, changes in flow rate (if temperature, flow be not in unit normal operation range, adjusting accordingly);
As unit parameter meets normal operation, finally should checking unit Boiler Pipe and wall temperature measuring point, appraising and deciding with or without exceeding the maximum oxidation resistance temperature of this material.
According to specific embodiment of the invention scheme, inventor finds that dissolved hydrogen content is also subject to the impact of water condition particularly dissolved oxygen under study for action, specifically can be reflected in oxygen content in main steam and can cause certain influence for the dissolved hydrogen content in main steam and reheated steam.Main steam oxygen content is high, main steam and reheated steam dissolved hydrogen content low; Otherwise main steam oxygen content is low, dissolved hydrogen content will rise.Thus, according to specific embodiment of the invention scheme, the method for monitoring generating set high temperature scale situation of the present invention, wherein, also can optimize and revise as follows the operation in Unit Commitment process, unit operation operating mode further:
Oxygenated treatment is carried out to unit feedwater.Such Optimized Measures has positive effect for preventing the corrosion of unit heating surface, is conducive to the formation of heating surface diaphragm.Particularly when dissolved hydrogen content in main steam in unit running process and/or reheated steam is obviously higher, such as, when being greater than 2.0 μ g/kg, can the deficiency of illustrative system oxygen-adding amount, prompting operations staff suitably can improve the oxygen-adding amount of feedwater.
On the other hand, present invention also offers the monitoring device (system) for realizing above-mentioned monitoring method, this device comprises:
For monitoring the dissolved hydrogen analysis meter of the dissolved hydrogen content that economizer entrance in generating set boiler circuit, steam-water separator outlet, superheater outlet and reheater export;
The instrument of monitoring unit parameter;
The instrument of monitoring water condition parameter;
For gathering Monitoring Data from described dissolved hydrogen analysis meter and the instrument of monitoring unit parameter and the instrument of monitoring water condition parameter to set up the industrial control system (industry control unit) of unit parameter, relation between water condition parameter and the change of dissolved hydrogen.
Utilize monitoring device of the present invention, by analyzing described Monitoring Data, set up unit parameter, relation between water condition parameter and the change of dissolved hydrogen, can than the changes of contents more comprehensively reflecting dissolved hydrogen in boiler circuit, analyze the influence degree of hydrogen content by the factor such as unit parameter, water condition, and then disclose the oxidation rate of metal, tracking and monitoring can be carried out to the corrosion of unit generation and oxidization condition in real time.
More specifically, described unit parameter comprises unit load, also optionally comprises one or more parameters in metal temperature, flow, pressure.
More specifically, described water condition comprises dissolved oxygen, also optionally comprises one or more parameters in pH value, electrical conductivity etc.
In addition, because hydrogen content also may be subject to the impact of other parameters (as metal material etc.).Therefore, according to specific embodiment of the invention scheme, monitoring device of the present invention also can comprise the measuring instrument of other parameters of monitoring (unit boiler tubing and wall temperature etc.) further, described industrial control system can gather the data of these measuring instruments to carry out analyzing and diagnosing simultaneously, thus can after comprehensive each Monitoring Data carries out analyzing and diagnosing, assessment metal material oxidation speed, and then unit thermal parameter and water condition are optimized, reduce the speed of unit corrosion and oxidation to the full extent.
According to specific embodiment of the invention scheme, described dissolved hydrogen analysis meter is connected to industrial control system by analog-digital converter; The instrument of the instrument of described monitoring unit parameter, monitoring water condition parameter, the instrument of monitoring other parameters (unit boiler tubing and wall temperature etc.) can be connected to industrial control system respectively by scattered control system.
The instrument and equipment such as each instrument, analog-digital converter, scattered control system, industrial control system in the present invention all can adopt prior art.According to specific embodiment of the invention scheme, described industrial control system can Monitoring Data collected by automatic analysis, and sets up unit parameter, relation between water condition parameter and the change of dissolved hydrogen.
According to specific embodiment of the invention scheme, industrial control system (industry control unit) in the present invention also can according to the relation between parameter and the change of dissolved hydrogen such as set up unit parameter, water condition, there is provided the information operation in Unit Commitment process, unit operation operating mode being optimized to adjustment, to reduce corrosion and the oxidation of unit to greatest extent.
The beneficial effect of technical solution of the present invention:
For part for overcritical and above unit; it is very distinct issues that superheater and reheater oxide skin large area come off; the measure of " meet and stop to detect " that present most of power plant adopts; as long as namely there is shutdown chance; all need the stripping situation of superheater and reheater tubing oxide skin to carry out by root investigation, this needs a large amount of human and material resources, to check 800,000 yuan at every turn; average every platform compressor emergency shutdown No. 3 meters, every nearly 2,400,000 yuan of platform crew check oxide skin expense.If there occurs large area oxide skin to come off the plugging stopping accident caused, its cleaning up cost and because shutting down the loss that causes at least more than ten million yuan.In addition, the particle that unit thermodynamic system corrosion product and oxide skin come off can produce erosion to each speed governing door of main steam valve, boiler circuit and turbine blade, on the one hand, can cause the bite of related valve, bring hidden danger to the safe and stable operation of unit.On the other hand, corrosive particles can deposit in therrmodynamic system, have impact on the efficiency of unit.Utilize method of the present invention, by the monitoring of boiler circuit dissolved hydrogen content and unit parameter, water condition parameter, metal erosion that unit is occurred can be realized and oxidization condition carries out tracking and monitoring, obtain the effective information of high temperature scale rate of rise.And according to this information result, adjustment is optimized to unit operation operating mode, thus avoid because of oxide skin increase fast after peel off the generation that can cause plugging or cause overtemperature tube burst leakage accident, reduce corrosion and the oxidation of unit metal material to greatest extent.One-time investment about 500,000 yuan is put in repacking, and maintenance cost is almost nil, and its economic benefit clearly.
Utilize method of the present invention, by the observation to dissolved hydrogen analyzer reading, in conjunction with unit parameter, water condition parameter situation, have the corrosion occurred in therrmodynamic system and the most directly judged, thus actively take measures on customs clearance, reduce dissolved hydrogen content, reduce the generation of corrosion.In the present invention, also can carry out Real-Time Monitoring to dissolved hydrogen content, unit parameter, water condition parameter further, set up the variation relation of the dissolved hydrogen that unit operations is brought, thus adjustment is optimized to the operation in Unit Commitment process, unit operation operating mode, reduce corrosion and the oxidation of unit to greatest extent, ensure the safe and stable operation of unit.Online dissolved hydrogen analyzer is easy for installation, and routine use is safeguarded simple, can not cause potential safety hazard to original system.
In sum, the invention provides a kind of method and device of monitoring generating set high temperature scale situation, metal erosion that unit is occurred can be realized and oxidization condition carries out tracking and monitoring, obtain the effective information of high temperature scale rate of rise.And according to this information result, adjustment is optimized to unit operation operating mode, thus avoid because of oxide skin increase fast after peel off the generation that can cause plugging or cause overtemperature tube burst leakage accident, reduce corrosion and the oxidation of unit metal material to greatest extent.
Accompanying drawing explanation
Fig. 1 is the therrmodynamic system structural representation showing monitoring point of the present invention.In figure, 1 condenser, 2 condensate pumps, 3 low-pressure heaters, 4 oxygen-eliminating devices, 5 feed pumps, 6 high-pressure heaters, 7 economizers, 8 water-cooling walls, 9 steam-water separators, 10 superheaters, 11 reheaters, 12 high pressure cylinders, 13 intermediate pressure cylinders, 14 low pressure (LP) cylinders, 15 dissolve hydrogen meter H1,16 dissolve hydrogen meter H2, and 17 dissolve hydrogen meter H3, and 18 dissolve hydrogen meter H4.
Fig. 2 is the structural representation of the device (system) of monitoring generating set high temperature scale situation of the present invention.
Fig. 3 is the schematic diagram of the device (system) of the monitoring generating set high temperature scale situation of a specific embodiment of the present invention.
Fig. 4 is that in the present invention one specific embodiment, unit starting stage boiler circuit dissolves assay curve map.
Fig. 5 is the graph of relation of unit load and boiler circuit dissolved hydrogen content in the present invention one specific embodiment.
Fig. 6 is that in the present invention one specific embodiment, Unit Steam Water system dissolves hydrogen contains the graph of relation with superheated steam dissolved oxygen content.
Detailed description of the invention
Describe the beneficial effect of implementation process of the present invention and generation below by way of specific embodiment in detail, be intended to help reader to understand essence of the present invention and feature better, not as can the restriction of practical range to this case.
Embodiment 1
Between generating set down period, dissolved hydrogen analyzer is installed in Unit Steam Water system.Described boiler circuit mainly comprises reheater 11, intermediate pressure cylinder 13, low pressure (LP) cylinder 14, condenser 1, condensate pump 2, low-pressure heater 3, oxygen-eliminating device 4, feed pump 5, high-pressure heater 6, economizer 7, water-cooling wall 8, steam-water separator 9, superheater 10, high pressure cylinder 12 successively according to fluid upstream and downstream direction, as shown in Figure 1.Installing according to choosing four points shown in Fig. 1 the monitoring that dissolved hydrogen analyzer (dissolving hydrogen meter) carries out dissolved hydrogen, is economizer entrance, steam-water separator outlet, superheater outlet and reheater outlet respectively.
Wherein, the dissolved hydrogen that the dissolving hydrogen meter H1 monitoring economizer entrance records mainly informs the integrated information in water system, and because stokehold system temperature is lower, the amount of precipitation of hydrogen content is lower, can it can be used as background value; Dissolving hydrogen meter H2 for detecting the hydrogen concentration of steam-water separator outlet, utilizing dissolving hydrogen meter H2 dissolved hydrogen monitor value to compare with dissolving hydrogen meter H1 dissolved hydrogen monitor value, corrosion and the oxidization condition of economizer and water-cooling wall can be reflected in conjunction with other parameters; Dissolving hydrogen meter H3 for monitoring superheater outlet dissolved hydrogen, utilizing dissolving hydrogen meter H3 dissolved hydrogen monitor value to compare with dissolving hydrogen meter H2 dissolved hydrogen monitor value, superheater system corrosion and oxidization condition can be reflected in conjunction with other parameters; Dissolving hydrogen meter for monitoring reheater outlet dissolved hydrogen, utilizing dissolving hydrogen meter H4 dissolved hydrogen monitor value to compare with dissolving hydrogen meter H3 dissolved hydrogen monitor value, the oxidation states of province's reheater system can be reflected in conjunction with other parameters.
From the hydrogen conductivity table draining of above-mentioned four monitoring points, be connected to the NPT pipe at dissolved hydrogen analyzer chest rear portion with pressure hose diversion sample, enter analyzer.The temperature of water sample must at 21 DEG C to 38 DEG C, and pressure fixing (if the change of water sample pressure is more than 10%, uses pressure regulator) between 5 ~ 50psi ± 10%.Hydrogen analyzer can select any instrument realizing the function of described monitoring dissolved hydrogen content in prior art, preferably can select the measuring cell based on thermal conduction principle, to increase the stability of measurement, and reduce line service amount, faraday's electrolysis calibration function should be had simultaneously, facilitate calibrating indicating instrument.More preferably analyzer power requirement is 300W/220V/50 or 60Hz, and power taking source powers to analyzer nearby.Analyzer range is 0 ~ 5(or 0 ~ 20) μ g/kg, output signal as direct current 0 ~ 20(or 4 ~ 20) mA, analyser output signal is caused industrial control system after A/D conversion.
Shown in Fig. 2 and Fig. 3, the device (system) of monitoring generating set high temperature scale situation of the present invention comprises for monitoring economizer entrance in generating set boiler circuit, steam-water separator exports, superheater outlet, with the dissolved hydrogen analysis meter (monitoring the dissolving hydrogen meter of described four some dissolve hydrogen concentrations) 101 of the dissolved hydrogen content of reheater outlet, the instrument 102 of monitoring unit parameter, the instrument 103 of monitoring water condition parameter, also comprise and data acquisition is carried out to analyze and to set up unit parameter to each instrument monitoring data, the industrial control system (industry control unit) 104 of the relation between water condition parameter and the change of dissolved hydrogen, wherein, described dissolved hydrogen analysis meter is connected to industrial control system by modulus converter A/D, the instrument of described monitoring unit parameter, the instrument of monitoring water condition parameter are connected to industrial control system respectively by distributed monitoring control system (not showing DCS in Fig. 3).By described monitoring, than the changes of contents more comprehensively reflecting dissolved hydrogen in boiler circuit, the influence degree of hydrogen content by the factor such as unit parameter, water condition parameter can be analyzed, and then disclose the oxidation rate of metal.In addition, hydrogen content also may be subject to the impact of other parameters (unit boiler tubing material and wall temperature etc.), therefore, the device of monitoring generating set high temperature scale situation of the present invention also can comprise the measuring instrument 105 of other parameters of monitoring (metal material etc.) further, this instrument is connected to industrial control system by analog-digital converter DCS, so that described industrial control system can gather the data analysis diagnosis of these measuring instruments simultaneously, after comprehensive each Monitoring Data carries out analyzing and diagnosing, assessment metal material oxidation speed, and then unit thermal parameter and water condition are optimized, reduce unit corrosion and the speed be oxidized to the full extent.
Fig. 4 reflects between certain No.3 in Power Plant unit starting period in February, the situation of change of each monitoring point dissolved hydrogen content.As can be seen from the figure, during unit starting, main steam, reheated steam dissolved hydrogen content are all in higher level, reach 10 μ g/kg and 20 μ about g/kg respectively.This is mainly because unit is when just starting, and water and steam quality is not good, does not reach level during normal operation, causes the corrosion of unit heating surface; In addition, unit is through last shutdown, and the stand-by phase after shutting down, and can cause the destruction of part at the diaphragm that normal operating phase is formed to unit heating surface, in the region that these diaphragms are destroyed, corrosion more easily occurs.
Known by above analysis, when unit normally runs, economizer entrance, steam-water separator, superheater outlet, reheater outlet dissolved hydrogen maintains reduced levels, and content is all at 2 below μ g/kg.During unit starting, carbonated drink water system hydrogen content obviously rises, and reaches 10 μ g/kg ~ 20 μ g/kg and illustrates that corrosion of metal speed is accelerated.By the monitoring of unit starting stage boiler circuit dissolved hydrogen, can reflect metal material startup stage extent of corrosion, can assess the effect of protection of boiler during shutdown period between down period to a certain extent simultaneously, such as, statistical analysis can be carried out to the water quality after all previous unit starting and hydrogen content, when operating mode is roughly the same, dissolved hydrogen content obvious higher time illustrate that between unit lay-off period, anticorrosion ability is bad; Otherwise, if dissolved hydrogen content is on the low side, illustrate that between unit lay-off period, anticorrosion ability is better.Visible, instruct operations staff to be optimized protection of boiler during shutdown period technique by hydrogen content index; When startup stage hydrogen content apparently higher than normal value time, prompting operations staff should strengthen the flushing of unit starting, and suitably improves feedwater pH value.
Fig. 5 mainly shows the variation relation of each sample point dissolved hydrogen content random groups load.As can be seen from the figure, economizer entrance, steam-water separator place dissolved hydrogen content are lower, all fluctuate at 1 below μ g/kg, water supply system, economizer are described, corrosion that water-cooling wall place occurs is less, and in main steam and reheated steam, content is slightly high, be engraved in when the corrosion reaction of high-temperature steam and iron-based body in superheater and reheater is described and carry out, from variation tendency, the fluctuation change of corrosion reaction degree random groups load is obvious, during load height, dissolved hydrogen content rises thereupon, and instrument response is rapid.But with regard to overall variation amount, in main steam and reheated steam, hydrogen content is lower, substantially at 2.0 below μ g/kg, illustrates that superheater, reheater oxide skin are more complete, peel off and crushing less, oxide skin rate of rise is slow.
According to the size of hydrogen content, early warning analysis can be carried out to abnormal conditions in unit running process, simultaneously for the unit that hydrogen content is obviously higher, thermal parameter and water condition Optimized Measures can be proposed according to the change of hydrogen content.Such as, if unit steam dissolved hydrogen content in normal operation rises suddenly, apparently higher than 2.0 μ g/kg, illustrate that rate of metal corrosion is accelerated.At this moment operations staff first should to check that Steam-water Quality has without exception, especially system pH value is with or without decline; If Steam-water Quality is without exception, the operational circumstances of unit should be checked, as met the elevation rate of unit load, the situation of change of temperature, flow.Finally should checking unit Boiler Pipe and wall temperature measuring point, appraising and deciding the generation with or without exceeding the maximum oxidation resistance temperature of this material.
The change of oxygen content in main steam that what Fig. 6 blue line (lines four) represented is, as can be seen from the figure, in main steam, oxygen content can impact for the dissolved hydrogen content in main steam and reheated steam.Main steam oxygen content is high, main steam and reheated steam dissolved hydrogen content low; Otherwise main steam oxygen content is low, dissolved hydrogen content will rise.This also illustrates, unit Feedwater oxygen treatment has positive effect for preventing the corrosion of unit heating surface, is conducive to the formation of heating surface diaphragm.
For oxygenation unit, if superheated steam dissolved hydrogen content is obviously higher, the deficiency of illustrative system oxygen-adding amount, prompting operations staff suitably should improve the oxygen-adding amount of feedwater.If superheated steam dissolved hydrogen content obviously adds higher for a long time, illustrate that superheater oxide skin is in and increase state fast, or be attended by the fragmentation of oxide skin and come off, at this moment should notice that unit has oxide skin to block the risk of steam pipe.The visible size according to superheated steam hydrogen content carrys out optimizing index parameter, makes unit be in optimum operating condition and runs.
Claims (8)
1. monitor a method for generating set high temperature scale situation, the method comprises:
The dissolved hydrogen content of economizer entrance in boiler circuit when starting generating set and in running, steam-water separator outlet, superheater outlet and reheater outlet carries out real time on-line monitoring; And monitor unit parameter, water condition parameter;
Gather Monitoring Data, analyze and set up unit parameter, relation between water condition parameter and the change of dissolved hydrogen, the corrosion occurred unit in real time and oxidization condition carry out tracking and monitoring;
The method also comprises:
According to Monitoring Data and unit parameter, relationship analysis between water condition parameter and the change of dissolved hydrogen, adjustment is optimized to the operation in Unit Commitment process, unit operation operating mode, to reduce corrosion and the oxidation of unit to greatest extent;
Wherein, according to anticorrosion ability before main steam, reheated steam dissolved hydrogen content Monitoring Data assessment water and steam quality and unit starting during unit starting;
When unit starting, main steam dissolved hydrogen content is greater than 10 μ g/kg and/or reheated steam dissolved hydrogen content when being greater than 20 μ g/kg, optimizes and revises as follows the operation in Unit Commitment process, unit operation operating mode:
Flushing when anti-corrosion protection measure during strengthening compressor emergency shutdown, reinforcement unit starting, and/or
Suitable raising feedwater pH value.
2. method according to claim 1, wherein, described unit parameter comprises unit load, and described unit parameter also comprises one or more parameters in metal temperature, flow, pressure further; Described water condition comprises dissolved oxygen.
3. method according to claim 1, wherein, described water condition also comprises one or more parameters in pH value, electrical conductivity further.
4. method according to claim 1, wherein, in unit running process, economizer entrance, steam-water separator place dissolved hydrogen content at 1 below μ g/kg, illustrate water supply system, economizer, water-cooling wall place occur corrosion less; In main steam and reheated steam, dissolved hydrogen content is at 2.0 below μ g/kg, illustrates that superheater, reheater oxide skin are more complete, peel off and crushing less, oxide skin rate of rise is slow.
5. method according to claim 4, wherein, when dissolved hydrogen content in main steam in unit running process and/or reheated steam is greater than 2.0 μ g/kg, the operation in Unit Commitment process, unit operation operating mode are optimized and revised as follows:
First check that Steam-water Quality has without exception, comprises check system pH value with or without decline;
If Steam-water Quality is without exception, check the elevation rate of unit load;
Elevation rate as unit load meets normal operation, checks temperature, changes in flow rate unit parameter situation;
As unit parameter meets normal operation, finally should checking unit Boiler Pipe and wall temperature measuring point, appraising and deciding with or without exceeding the maximum oxidation resistance temperature of unit boiler tubing material.
6. the method according to claim 4 or 5, wherein, when dissolved hydrogen content in main steam in unit running process and/or reheated steam is greater than 2.0 μ g/kg, the operation in Unit Commitment process, unit operation operating mode are optimized and revised as follows:
Oxygenated treatment is carried out to unit feedwater.
7. monitor a device for generating set high temperature scale situation, this device comprises:
For monitoring the dissolved hydrogen analysis meter of the dissolved hydrogen content that economizer entrance in generating set boiler circuit, steam-water separator outlet, superheater outlet and reheater export;
The instrument of monitoring unit parameter;
The instrument of monitoring water condition parameter;
For gathering Monitoring Data from described dissolved hydrogen analysis meter and the instrument of monitoring unit parameter and the instrument of monitoring water condition parameter to set up the industrial control system of unit parameter, relation between water condition parameter and the change of dissolved hydrogen.
8. device according to claim 7, this device comprises the measuring instrument of monitoring unit Boiler Pipe and wall temperature parameter further, and described industrial control system can gather the data of these measuring instruments to carry out analyzing and diagnosing simultaneously.
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| CN104950131B (en) * | 2015-07-15 | 2018-04-06 | 西安净源水处理科技有限公司 | Superheater oxide skin irrigation flow rate determines device |
| CN109084829B (en) * | 2018-06-20 | 2020-12-18 | 淮浙煤电有限责任公司凤台发电分公司 | Method for verifying and calibrating oxidation rate of high-temperature heating surface of supercritical thermal generator set |
| CN110083857B (en) * | 2019-03-08 | 2023-12-29 | 中国大唐集团科学技术研究院有限公司火力发电技术研究院 | Austenite heat-resistant steel magnetic transformation and oxide scale service life assessment method |
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