CN103216846B - Smoke concentration adjustment method and smoke concentration adjustment system when fire coal variety of pulverized coal boiler is changed - Google Patents
Smoke concentration adjustment method and smoke concentration adjustment system when fire coal variety of pulverized coal boiler is changed Download PDFInfo
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Abstract
The invention discloses a smoke concentration adjustment method after the fire coal variety of a pulverized coal boiler is changed. The smoke concentration adjustment method after the fire coal variety of the pulverized coal boiler is changed comprises the following steps: establishing a meshing structural model of the boiler, establishing a mathematical model of each physical and chemical process formed by combustion of pulverized coal; imitating a pulverized coal combustion process after the fire coal variety of the pulverized coal boiler is changed, and obtaining a corresponding relation between various smoke concentration situations and boiler combustion performance indexes; and adjusting the smoke concentration of the boiler so that the boiler meets preset combustion performance indexes. Besides, the invention further discloses a smoke concentration adjustment system after the fire coal variety of the pulverized coal boiler is changed. The smoke concentration adjustment method and the smoke concentration adjustment system after the fire coal variety of the pulverized coal boiler is changed can improve the accuracy and safety of smoke concentration control after the fire coal variety of the pulverized coal boiler is changed, resolve the problems of unstable combustion in the boiler and low combustion efficiency easily caused by manual control, and largely lower pollutants produced in the combustion process.
Description
Technical field
The present invention relates to pulverized-coal fired boiler technical field, particularly relate to a kind of pulverized-coal fired boiler change coal-fired kind after flue gas concentration method of adjustment and a kind of pulverized-coal fired boiler change the flue gas concentration adjustment System after coal-fired kind.
Background technology
Along with power consumption is increasing, the demand of coal is also got more and more, the production of electric coal and transport more and more outstanding with the contradiction of need for electricity, become the bottleneck that restriction current Chinese economy develops.While coal supply constant tension, coal price also rises steadily, and causes cost of electricity-generating constantly to increase.For reducing cost of electricity-generating, power plant starts to find low price coal one after another, and this just causes most power plant to be difficult to ensure to use single design coal for a long time.In addition, coal resource distribution is uneven, makes to transport the coal in the North to the South, and transferring coal from the west to the east becomes normality.Because of the factor such as wretched insufficiency of transport power, cause a lot of power plant must mix burning to boiler and even change burning.
In this case, power plant has started to use non dipper, at Boiler Mixed Burning non dipper.But due to the restriction of objective condition, what mix burning is the simple arithmetic addition of each composition in coal according to what substantially adopt, the method coal close to the combustion characteristics of Quality of Part Coal, coal ash meltbility is basic feasible solution, but to burning of coal characteristic or grey property difference larger time, mix burning and there is the dangerous and uneconomic problem of boiler operatiopn.Meanwhile, burn for a long time, mix greenhouse gases that burning inferior coal kind brings and noxious gas emission is also cause one of extensive concern large problem.Consumption of coal is again the main cause causing SO2 (sulfur dioxide) to discharge, and the SO2 discharge of more than 80% comes from coal fire discharged, a large amount of SO2 discharge and produced large-area Acid Rain Zone.Energy-consuming is also cause the main cause of greenhouse gas emission, and the pressure of GHG emissions mitigation has become very urgent.Therefore, for the power plant using non dipper for a long time, in order to strengthen the adaptability of large thermal power plant to coal, reduce cost of electricity-generating, improve economy and the security of power plant, numerous power plant has to start to carry out the system reform to meet the demands to boiler.Such as Tianjin Dagang Power Plant is transformed 300MW unit, changes burning bituminous coal and replaces original meager coal design coal; And for example Yunfu Power Plant is for carrying out large the brought series of problems of coal coal varitation, transforms the burner region of steam generator system and pulverized coal preparation system.
But for quadrangle tangential circle pulverized-coal fired boiler widely used in power plant, change (such as Lean Coal-fired Boiler changes burning bituminous coal) after burning non dipper, in different flue gas concentration situations on also lacking ripe engineer applied in the affecting of boiler combustion characteristic, such as boiler changes and burns the impact on aspects such as boiler combustion exhausted, slagging scorification and dust stratifications of coal characteristic change after other coal-fired kind, be rely on artificial experience to control at present mostly, had a strong impact on security and the economy of boiler operatiopn.
Summary of the invention
Based on this, the invention provides a kind of pulverized-coal fired boiler change coal-fired kind after flue gas concentration method of adjustment and a kind of pulverized-coal fired boiler change the flue gas concentration adjustment System after coal-fired kind.
Pulverized-coal fired boiler changes the flue gas concentration method of adjustment after coal-fired kind, comprises the following steps:
According to the design parameter of quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, set up the gridding structural model of described boiler;
According to described gridding structural model, set up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
According to the described Mathematical Modeling set up, the process of coal combustion after described boiler changes coal-fired kind is simulated, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications; Wherein, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature;
According to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.
Compared with general technology, flue gas concentration method of adjustment after pulverized-coal fired boiler of the present invention changes coal-fired kind sets up the Mathematical Modeling corresponding with each physical and chemical processes that coal dust firing is formed, the method of employing numerical simulation obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications, and according to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.The present invention is consuming time short in numerical simulation, assesses the cost low, and the regulation and control at implementation procedure Zhong Buxu power plant scene coordinate, and analog result has good visuality.The present invention can improve pulverized-coal fired boiler and change the accuracy rate and security that flue gas concentration controls after coal-fired kind, overcome the problem that stove combustion is unstable and efficiency of combustion is low adopting Artificial Control easily to cause, greatly reduce the pollutant produced in combustion process simultaneously.
Pulverized-coal fired boiler changes the flue gas concentration adjustment System after coal-fired kind, comprises configuration model module, Mathematical Models module, analog module and adjusting module;
Described configuration model module, for the design parameter according to quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, set up the gridding structural model of described boiler;
Described Mathematical Models module, for according to described gridding structural model, sets up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
Described analog module, for according to the described Mathematical Modeling set up, simulates the process of coal combustion after described boiler changes coal-fired kind, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications; Wherein, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature;
Described adjusting module, for according to the described corresponding relation obtained, adjusts the flue gas concentration of described boiler, makes described boiler meet default combustibility index.
Compared with general technology, flue gas concentration adjustment System after pulverized-coal fired boiler of the present invention changes coal-fired kind sets up the Mathematical Modeling corresponding with each physical and chemical processes that coal dust firing is formed, the method of employing numerical simulation obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications, and according to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.The present invention is consuming time short in numerical simulation, assesses the cost low, and the regulation and control at implementation procedure Zhong Buxu power plant scene coordinate, and analog result has good visuality.The present invention can improve pulverized-coal fired boiler and change the accuracy rate and security that flue gas concentration controls after coal-fired kind, overcome the problem that stove combustion is unstable and efficiency of combustion is low adopting Artificial Control easily to cause, greatly reduce the pollutant produced in combustion process simultaneously.
Accompanying drawing explanation
Fig. 1 is the schematic flow sheet that pulverized-coal fired boiler of the present invention changes the flue gas concentration method of adjustment after coal-fired kind;
Fig. 2 is the gridding schematic diagram of chamber structure;
Fig. 3 is the CONCENTRATION DISTRIBUTION schematic diagram of burner centre cross section smoke components;
Fig. 4 is the CONCENTRATION DISTRIBUTION schematic diagram of middle level burner and burnout degree cross section smoke components;
Fig. 5 is the velocity field schematic diagram in burner centre cross section;
Fig. 6 is the velocity field schematic diagram that orlop runs Secondary Air burner cross section and burnout degree cross section;
Fig. 7 is the Temperature Distribution schematic diagram of burner cross section and burner hearth central cross-section;
Fig. 8 is each cross section burner temperature distribution schematic diagram;
Fig. 9 is the pulverized coal particle movement locus figure of different-grain diameter;
Figure 10 is the structural representation that pulverized-coal fired boiler of the present invention changes the flue gas concentration adjustment System after coal-fired kind.
Detailed description of the invention
For further setting forth the technological means that the present invention takes and the effect obtained, below in conjunction with accompanying drawing and preferred embodiment, to technical scheme of the present invention, carry out clear and complete description.
Refer to Fig. 1, for pulverized-coal fired boiler of the present invention changes the schematic flow sheet of the flue gas concentration method of adjustment after coal-fired kind.Pulverized-coal fired boiler of the present invention changes the flue gas concentration method of adjustment after coal-fired kind, comprises the following steps:
S101, according to the design parameter of quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, sets up the gridding structural model of described boiler;
According to the flow behavior of burner outlet, as boiler-burner entrance boundary condition, build domain and carry out stress and strain model, increasing the level of 4m and the contraction section of 4m at furnace outlet, to obtain fully developed flow in exit.In order to obtain high-quality computing grid, adopt multiblock technique division methods, adopt structuring hexahedral mesh, in order to accurate simulation burner outlet aerodynamic field, burner inlet region needs to carry out grid local cypher, and total grid number is 2,000,000.As shown in Figure 2, be the gridding schematic diagram of chamber structure.
As one of them embodiment, in the step of the described gridding structural model setting up described boiler, described design parameter comprises evaporation capacity, main steam pressure, main steam temperature, reheated steam flow, reheated steam inlet pressure, reheated steam outlet pressure, reheated steam inlet temperature, reheated steam outlet temperature, feed temperature, exhaust gas temperature, hot blast temperature, boiler efficiency, calculated fuel consumption, actual fuel consumption and burner design parameter.
When setting up gridding methods, necessary design parameter need all comprise, and can guarantee like this to set up effective model.In addition, design parameter is more, then the model set up is more accurate.Table 1 is the embodiment of a boiler main design parameters.
Table 1 boiler main design parameters
As one of them embodiment, described burner design parameter comprises First air, Secondary Air, tertiary air, First air surrounding air, tertiary air surrounding air and burner hearth and leaks out.
When setting up gridding methods, burner design parameter is The more the better, can guarantee like this to set up effectively and model accurately.Table 2 is the embodiment of a burner design parameter.
Table 2 burner design parameter
| Project | Wind rate % | Wind speed m/s | Wind-warm syndrome DEG C |
| First air | 15 | 22.7 | 243 |
| Secondary Air | 56.1 | 46.5 | 350 |
| Tertiary air | 19 | 56.1 | 120 |
| First air surrounding air | 4 | 40 | 350 |
| Tertiary air surrounding air | 1.9 | 10.8 | 350 |
| Burner hearth leaks out | 4 | -- | Cold wind |
FLUENT provides separate type and manifold type two class solver, and manifold type is divided into implicit expression and explicit two kinds.
Separate type solver (segregated solver) solves each equation (equation about u, v, w, p and T) sequentially, seriatim.After namely first solving an equation (as the u equation of momentum) on total-grid, then separate another one equation (as the v equation of momentum).Because governing equation is nonlinear, and be coupling each other, therefore, before obtaining convergence solution, through too much taking turns iteration.Each is taken turns iteration and is made up of following steps:
According to the result of current solution, upgrade all flow variables.Just start if calculated, then upgrade with initial value;
Solve u, v and w equation of momentum respectively in order, obtain velocity field.When calculating, the mass flow of pressure and unit interface uses current given value;
The speed obtained because of previous step does not probably meet continuity equation, therefore, constructs the pressure correction equation of a Poisson type with continuity equation and the linearizing equation of momentum, then solves this pressure correction equation, obtain the correction value of pressure field and velocity field;
Utilize the velocity field and pressure field that newly obtain, solve the governing equation of other scalars (as temperature, tubulence energy and component etc.);
For the simulation comprising discrete phase, when inside exists Coupling Between Phases, upgrade the source item of continuous phase according to the trajectory calculation result of discrete phase;
Check whether equation group restrains.If do not restrain, get back to the first step, repeat.
Manifold type solver (coupled solver) is the coupled wave equation simultaneously solving continuity equation, the equation of momentum, energy equation and component transport equation, then, then solves turbulent flow equiscalar equation seriatim.Because governing equation is nonlinear, and be coupling each other, therefore, before obtaining convergence solution, through 2 iteration.Each is taken turns iteration and is made up of following steps:
According to the result of current solution, upgrade all flow variables.Just start if calculated, then upgrade with initial value;
Solve the Couple Equations (latter two equation optionally solves) of continuity equation, the equation of momentum, energy equation and component transport equation simultaneously;
As required, turbulent flow, radiation equiscalar equation is solved seriatim.Noted before solving, the relevant variable used in the equation result obtained above upgrades;
For the simulation comprising discrete phase, when inside exists Coupling Between Phases, upgrade the source item of continuous phase according to the trajectory calculation result of discrete phase;
Check whether equation group restrains.If do not restrain, get back to the first step, repeat.
Two kinds of solvers are all applicable to from being pressed onto a wide range of flowing can pressed at a high speed, but generally, when calculate at a high speed can baric flow move time, manifold type solver has more advantage.Manifold type solver usually can very rapid convergence, but required internal memory is approximately 1.5 to 2 times of separate type solver.
In addition, the several physical models provided in separate type solver, do not have in manifold type solver.These physical models comprise: the cycle flow model of fluid volume model (VOF), multiphase mixture model, Euler's mixed model, PDF combustion model, pre-mixing combustion model, given mass flow, cyclical heat conduction model and shell conduction model etc.
Because the present invention will use PDF combustion model to simulate boiler combustion, and computer hardware configuration is limited, therefore selects separate type solver.
Three kinds of algorithms are provided: SIMPLE algorithm, SIMPLEC algorithm and PISO algorithm in FLUENT.SIMPLEC and PISO algorithm has convergence rate faster, reduces 30% ~ 50% relative to the computing time of SIMPLE algorithm.For transient problem, PISO algorithm has obvious advantage, and for steady state problem, can select SIMPLE serial algorithm.The present invention can select SIMPLE algorithm.
SIMPLE algorithm can be described below: for given pressure field, (it can be the value of supposition, or the result that obtains of last iterative computation), solve the equation of momentum of discrete form, draw velocity field, therefore, must given pressure field be revised.The principle revised is: the speed field energy corresponding with revised pressure field meets the continuity equation on this iteration level.Principle accordingly, we substitute into the discrete form of continuity equation the relation of the pressure of the discrete form defined by the equation of momentum and speed, thus obtain pressure correction equation, draw pressure correction value by pressure correction equation.Then, according to revised pressure field, new velocity field is tried to achieve.Then check whether velocity field restrains.If do not restrain, by revised force value as given pressure field, start the calculating of next level.So repeatedly, until obtain the solution of convergence.
S102, according to described gridding structural model, sets up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
Turbulent stress equation model:
The governing equation of turbulent flow is:
Continuity equation:
The equation of momentum (Navier-Stokes equation):
The transport equation of its dependent variable:
Visible, in equation group many six stress (3 direct stress and 3 shearing stress), that is:
For the processing mode of these six stress, obtain the method for various Numerical Simulation of Turbulent:
The present invention selects Realizable k-ε model to simulate.During standard k-ε model pair, the king-sized situation of equal strain rate, likely causes the direct stress born.And Realizable k-ε model Main change is:
Turbulent viscosity computing formula there occurs change, introduces and rotates the content relevant with curvature:
ε equation there occurs great changes, and the generation item in equation no longer includes the generation item Gk in k equation, and like this, present form illustrates the power conversion of spectrum better.
Item second from the bottom in ε equation does not have any singularity, even if k value is very little or be zero, denominator also can not be zero.This and standard k-ε model and RNG k-ε model have very large difference.
Realizable k-ε model must be applied to various dissimilar flow simulating by effective, comprise rotate uniform shear flow, include the flowing freely of jet and mixed flow, flowing in pipeline, boundary layer flow, and be with separative flowing etc.
Radiation patterns:
Radiation heat transfer problem can be calculated with 5 kinds of models in FLUENT, this in 5 model be discrete heat exchange radiation patterns (DTRM), P-1 radiation patterns, Rosseland radiation patterns, surface emissivity model (S2S) and discrete coordinates (DO) radiation patterns respectively.
Problem for the present invention's research is the burning of boiler, therefore selects P-1 radiation patterns.
P-1 radiation patterns, radiation environment evaluation is one and calculates relatively little diffusion equation, and contain scattering effect in model, in the computational problem that the optical thicknesses such as burning are very large, the calculating effect of P-1 model is all relatively good simultaneously.
Component transport and Chemical Reaction Model:
Four kinds of analogy methods are provided: general finite Rate Models in FLUENT; Non-premixed combustion model; Pre-mixing combustion model; Partly-premixed combination burning model.
The roughly policy of Model Selection is as follows:
General finite rate pattern is mainly used in: chemical constituent mixing, the problem transporting and react; The problem (as chemical vapour deposition) of wall or particle surface reaction;
Non-premixed combustion model is mainly used in: the reaction system comprising turbulent diffusion flame, and this system is close to chemical balance, and oxide wherein and fuel flow into the region that will calculate respectively with two or three runners;
Pre-mixing combustion model is mainly used in: single, fully premixed conjunction reagent flow;
Partly-premixed combination burning model is mainly used in: the situation in region with the premixed flame changing equivalent ratio;
The present invention selects non-premixed combustion model, with Hybrid analysis-probability density function simulation gas phase turbulent combustion.
NOx generation model:
NOx (nitrogen oxide) generates type three kinds: heating power type, Quick-type, fuel type.Formation mechanism is in chapter 1 introduction.Be the numerical simulation of coal dust firing based on research object of the present invention, therefore do not consider Quick-type NOx (it generates primarily of CH fuel combustion), but the fuel efficiency again considering NOx should.In addition, N is not considered in model
2the generation of O.
S103, according to the described Mathematical Modeling set up, simulates the process of coal combustion after described boiler changes coal-fired kind, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications;
As one of them embodiment, the coal-fired kind after described boiler changes is bituminous coal.
At present, bituminous coal is a kind of non dipper be widely adopted, and boiler changes the consumption rate of burning bituminous coal reduction coal dust.
As one of them embodiment, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature.
In simulation process, the combustibility index of analysis is more, higher in the accuracy rate controlled boiler operatiopn, and security is also better, more has directive significance to follow-up engineering practice.
Before simulation, need to carry out a comparative analysis to boiler design coal and Actual combustion coal.Table 3 is the embodiment of design coal conventional analysis data.
Table 3 designs coal conventional analysis data
Table 4 be one actual come the embodiment that is analyzed of the characteristic of coal and design coal.
Table 4 actual come the Property comparison of coal and design coal
| Coal | Q net,ar/(MJ·kg -1) | C ar/％ | V daf/％ |
| Design coal | 23.289 | 61.75 | 10.0 |
| Actual coal-fired | 18.8-24.0 | 52.0-66.5 | 4.5-30.0 |
Refer to Fig. 3, Fig. 3 is the CONCENTRATION DISTRIBUTION schematic diagram of burner centre cross section smoke components.
Refer to Fig. 4, Fig. 4 is the CONCENTRATION DISTRIBUTION schematic diagram of middle level burner and burnout degree cross section smoke components.Can find from figure, at burner hearth center O
2concentration is very low, and along with the increase of furnace height, oxygen concentration entirety is in rising trend, and at every grate firing burner regional area, due to supplementary air, have a fluctuation increased, in furnace outlet region, oxygen concentration tends to balance.Because burner region excess air coefficient is about 0.9, therefore, define the atmosphere district of a strong reducing property at burner region, a large amount of CO generates; The oxygen that CO and burnout degree supplement after burnout degree burns away and generates CO2, and to furnace arch, furnace nose place, CO is substantially all oxidized to CO
2, CO progressively reduces along with the increase of furnace height.
NOx generation amount is relevant with the nitrogen content of excess air coefficient, ignition temperature and coal.Distributed as can be seen from the NOx concentration in burner centre cross section, in burner outlet region, mix with coal dust because thermal-flame radiation and backflow flue gas entrainment a large amount of hot-airs, the temperature of pulverized coal particle improves rapidly, and volatile matter nitrogen is separated out in a large number; The intermediate products such as nitrogen is oxidized by oxygen rapidly, a large amount of generation HCN; The oxidation of HCN mono-aspect generates NOx, also with the NOx generated, reduction reaction can occur on the other hand, NOx concentration be reduced, reaches the highest in burner hearth central region NOx concentration.Between burner and burnout degree, also form the reduced zone of hypoxemia also fuel-rich material, NOx concentration reduces.Burning-out zone above burnout degree, due to the air needed for burnout degree aftercombustion, oxygen concentration increases, and can NOx generation amount a bit increase; But along with proceeding of furnace height and burning, NOx can move closer to again steadily.Fig. 4 is respectively burnout degree, first and third layer of First air burner, and orlop runs Secondary Air central cross-section smoke components O
2, CO and NOx concentration distribute.
Refer to Fig. 5, Fig. 5 is the velocity field schematic diagram in burner centre cross section.Burner centre cross section velocity field fully reflect burner liquidate arrange flow feature, air-flow is after burner hearth center is converged mutually, and center rises primary air in formation, upwards flows; Lower floor's burner part air-flow flows down to furnace hopper, forms whirlpool district; The speed of ascending air is about 15m/s, and air-flow degree of filling in burner hearth is good, distribution is reasonable, and along with the increase of furnace height, speed progressively increases.Obvious interaction is had between each burner.
Refer to Fig. 6, Fig. 6 is the velocity field schematic diagram that orlop runs Secondary Air burner cross section and burnout degree cross section.Air outlet velocity 45m/s to 50m/s, load actual conditions.Can find out, lower floor's Secondary Air prevents coal dust from emanating, and holds flame and is unlikely to undue undershoot, avoids unburned coal dust directly to fall into ash bucket.Burnout degree has very strong rigidity, can blow in the middle part of burner hearth.This can make burner upper area burning later stage mixing strengthen, and accelerates coal dust firing speed, improves coal dust burn-off rate.
Refer to Fig. 7, Fig. 7 is the Temperature Distribution schematic diagram of burner cross section and burner hearth central cross-section.Burner region uniformity of temperature profile, along with furnace height increases, flue-gas temperature raises gradually, and burner hearth high-temperature region is positioned at upper strata burner to burnout degree region; Burnout degree plays the effect of banking fire, also has one section of high-temperature region after burnout degree, and this is that the oxygen supplemented due to unburnt CO and C and burnout degree reacts.Along furnace chamber width, burner hearth central temperature is evenly distributed, and this will be conducive to reducing wall thermic load deviation.Can be found out by the Temperature Distribution in burnout degree cross section and substantially eliminate the circle of contact, furnace load is even.Can catch fire rapidly after breeze airflow enters burner hearth, add the time of staying of pulverized coal particle in high-temperature region, lighting fast and abundant after-flame of coal dust can be ensured.Fig. 8 is each cross section burner temperature distribution schematic diagram.Ignition distance is short, Pass Test requirement.
Refer to Fig. 9, Fig. 9 is the pulverized coal particle movement locus figure of different-grain diameter.As can be seen from the figure, the coal dust particle of orlop burner is owing to being subject to the impact of air-flow, and a part of coal dust particle can enter furnace hopper, likely causes uncombusted to lose and furnace hopper slagging scorification; After the coal dust particle of middle level burner enters burner hearth, owing to being subject to the impact of air-flow, coal dust particle is after particularly upper strata burner sprays into burner hearth, some coal dust particle can be affixed to water-cooling wall due to high temperature reflux flue gas, and coal dust is own higher through ignition temperature herein, and oxygen content is lower, if the coal that burning meltbility is lower, should be noted that the problem of region slagging scorification between upper strata burner region and burnout degree.
Under boiler base operation condition, the unburned combustible in fly ash of simulation is 0.311%, and coal dust burn-off rate is 99.85%, and NOx discharge is 211mg/m3 (6%O
2).Above analog result shows, this boiler is when using design coal or the coal close with design coal, and unburned combustible in fly ash is low, and efficiency of combustion is high, and NOx discharge is low, can realize the burning of coal dust clean and effective.
S104, according to the described corresponding relation obtained, adjusts the flue gas concentration of described boiler, makes described boiler meet default combustibility index.
The flue gas concentration of various method to boiler can be adopted to control, such as, can adopt and computerized control, also can manually control.
As one of them embodiment, after the described step that the flue gas concentration of described boiler is adjusted, comprise the following steps:
In the running of described boiler, when boiler combustion performance indications exceed default alarm index, then send alarm signal.
When boiler combustion performance indications exceed default alarm index, report to the police, the security of boiler implosion can be guaranteed to a greater degree.
Compared with general technology, flue gas concentration method of adjustment after pulverized-coal fired boiler of the present invention changes coal-fired kind sets up the Mathematical Modeling corresponding with each physical and chemical processes that coal dust firing is formed, the method of employing numerical simulation obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications, and according to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.The present invention is consuming time short in numerical simulation, assesses the cost low, and the regulation and control at implementation procedure Zhong Buxu power plant scene coordinate, and analog result has good visuality.The present invention can improve pulverized-coal fired boiler and change the accuracy rate and security that flue gas concentration controls after coal-fired kind, overcome the problem that stove combustion is unstable and efficiency of combustion is low adopting Artificial Control easily to cause, greatly reduce the pollutant produced in combustion process simultaneously.
Refer to Figure 10, for pulverized-coal fired boiler of the present invention changes the structural representation of the flue gas concentration adjustment System after coal-fired kind.
Pulverized-coal fired boiler of the present invention changes the flue gas concentration adjustment System after coal-fired kind, comprises configuration model module 201, Mathematical Models module 202, analog module 203 and adjusting module 204;
Described configuration model module 201, for the design parameter according to quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, set up the gridding structural model of described boiler;
Described Mathematical Models module 202, for according to described gridding structural model, sets up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
Described analog module 203, for according to the described Mathematical Modeling set up, simulates the process of coal combustion after described boiler changes coal-fired kind, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications;
Described adjusting module 204, for according to the described corresponding relation obtained, adjusts the flue gas concentration of described boiler, makes described boiler meet default combustibility index.
As one of them embodiment, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature.
In simulation process, the combustibility index of analysis is more, higher in the accuracy rate controlled boiler operatiopn, and security is also better, more has directive significance to follow-up engineering practice.
As one of them embodiment, also comprise alarm module;
Described alarm module, in the running of described boiler, when boiler combustion performance indications exceed default alarm index, sends alarm signal.
When boiler combustion performance indications exceed default alarm index, report to the police, the security of boiler implosion can be guaranteed to a greater degree.
Compared with general technology, flue gas concentration adjustment System after pulverized-coal fired boiler of the present invention changes coal-fired kind sets up the Mathematical Modeling corresponding with each physical and chemical processes that coal dust firing is formed, the method of employing numerical simulation obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications, and according to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.The present invention is consuming time short in numerical simulation, assesses the cost low, and the regulation and control at implementation procedure Zhong Buxu power plant scene coordinate, and analog result has good visuality.The present invention can improve pulverized-coal fired boiler and change the accuracy rate and security that flue gas concentration controls after coal-fired kind, overcome the problem that stove combustion is unstable and efficiency of combustion is low adopting Artificial Control easily to cause, greatly reduce the pollutant produced in combustion process simultaneously.
The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.
Claims (7)
1. pulverized-coal fired boiler changes the flue gas concentration method of adjustment after coal-fired kind, it is characterized in that, comprises the following steps:
According to the design parameter of quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, set up the gridding structural model of described boiler;
According to described gridding structural model, set up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
According to the described Mathematical Modeling set up, the process of coal combustion after described boiler changes coal-fired kind is simulated, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications; Wherein, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature;
According to the described corresponding relation obtained, the flue gas concentration of described boiler is adjusted, makes described boiler meet default combustibility index.
2. pulverized-coal fired boiler according to claim 1 changes the flue gas concentration method of adjustment after coal-fired kind, it is characterized in that, in the step of the described gridding structural model setting up described boiler, described design parameter comprises evaporation capacity, main steam pressure, main steam temperature, reheated steam flow, reheated steam inlet pressure, reheated steam outlet pressure, reheated steam inlet temperature, reheated steam outlet temperature, feed temperature, exhaust gas temperature, hot blast temperature, boiler efficiency, calculated fuel consumption, actual fuel consumption and burner design parameter.
3. pulverized-coal fired boiler according to claim 2 changes the flue gas concentration method of adjustment after coal-fired kind, and it is characterized in that, described burner design parameter comprises First air, Secondary Air, tertiary air, First air surrounding air, tertiary air surrounding air and burner hearth and leaks out.
4. pulverized-coal fired boiler according to claim 1 changes the flue gas concentration method of adjustment after coal-fired kind, it is characterized in that, the coal-fired kind after described boiler changes is bituminous coal.
5. pulverized-coal fired boiler according to claim 1 changes the flue gas concentration method of adjustment after coal-fired kind, it is characterized in that, after the described step adjusted the flue gas concentration of described boiler, comprises the following steps:
In the running of described boiler, when boiler combustion performance indications exceed default alarm index, send alarm signal.
6. the pulverized-coal fired boiler for realizing method described in claim 1 changes the flue gas concentration adjustment System after coal-fired kind, it is characterized in that, comprises configuration model module, Mathematical Models module, analog module and adjusting module;
Described configuration model module, for the design parameter according to quadrangle tangential circle pulverized-coal fired boiler, according to the structure in DC burner, furnace hopper region, burner region, burner upper area and pendant superheater region, set up the gridding structural model of described boiler;
Described Mathematical Models module, for according to described gridding structural model, sets up the Mathematical Modeling of gas-phase turbulent flow process, gas-solid two flow process, radiant heat transfer process and the NO_x formation process that coal dust firing is formed;
Described analog module, for according to the described Mathematical Modeling set up, simulates the process of coal combustion after described boiler changes coal-fired kind, obtains the corresponding relation between the various flue gas concentration situation of described boiler and boiler combustion performance indications; Wherein, described boiler combustion performance indications comprise coal dust burn-off rate, unburned carbon in flue dust, nitrogen oxide emission and lower hearth outlet temperature;
Described adjusting module, for according to the described corresponding relation obtained, adjusts the flue gas concentration of described boiler, makes described boiler meet default combustibility index.
7. pulverized-coal fired boiler according to claim 6 changes the flue gas concentration adjustment System after coal-fired kind, it is characterized in that, also comprises alarm module;
Described alarm module, in the running of described boiler, when boiler combustion performance indications exceed default alarm index, sends alarm signal.
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| CN103994463B (en) * | 2014-03-28 | 2016-09-28 | 广东电网公司电力科学研究院 | The acquisition methods of the lower combustion characteristics of different coal pulverizer combinations after boiler improvement |
| CN106503441B (en) * | 2016-10-20 | 2020-03-10 | 广东电网有限责任公司电力科学研究院 | Method and device for calculating heat of oxygen-enriched combustion pulverized coal boiler |
| CN106548032B (en) * | 2016-11-08 | 2019-04-05 | 沃森测控技术（河北）有限公司 | Based on boiler flue grid detection flue gas CO and O2The distribution field method for reconstructing of concentration |
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Address after: 510080 Dongfeng East Road, Dongfeng, Guangdong, Guangzhou, Zhejiang Province, No. 8 Patentee after: ELECTRIC POWER RESEARCH INSTITUTE, GUANGDONG POWER GRID CO., LTD. Address before: 510080 Dongfeng East Road, Dongfeng, Guangdong, Guangzhou, Zhejiang Province, No. 8 Patentee before: Electrical Power Research Institute of Guangdong Power Grid Corporation |