CN104896506A - Building method for combustion energy radiant energy signal in coal-fired thermal power generating unit boiler - Google Patents

Abstract

The invention discloses a building method for a combustion energy radiant energy signal in a coal-fired thermal power generating unit boiler and belongs to the technical field of thermal power plant boiler combustion monitoring and control. Firstly, image information of combustion flame is obtained through a plurality of flame image detectors arranged on different height positions along a boiler chamber, the grey value of each image is calculated in real time and transformed into a measuring range same as the thermal power generating unit actual generated power and defined as an initial radiant energy signal. Secondly, dynamic compensation data processing is performed on the initial radiant energy signal by the use of the value of the thermal power generating unit actual generated power, and the final radiant energy signal is obtained. Finally, the final radiant energy signal serves as a detection value of energy level in the boiler to be output to a coordinated control system of the thermal power generating unit. The application result shows that the radiant energy signal built by the method can effectively reflect the pulsatility of flame in the boiler chamber, the signal deviation caused by detector ash deposition and coking and other factors is eliminated, and the building method can be suitable for continuous on-line optimal control of thermal power generating units with different types and different capacities.

Description

A kind of construction method of fossil-fired unit stove combustion energy emission energy signal

Technical field

The present invention relates to a kind of construction method of fossil-fired unit stove combustion energy emission energy signal, belong to heat power plant boiler combustion monitoring and control technology.

Background technology

Furnace flame radiant image monitoring system is utilized to obtain radiant energy signal, on-line monitoring technique (the Zhou Huaichun that accurate reflection stove combustion process releases energy, furnace flame Visual retrieval philosophy and technique, Science Press, in May, 2005, pp.306-309) obtain certain achievement at fired power generating unit coordination optimization control field.

This technology is by installing many thermal-flame image detectors on pulverized coal firing boiler differing heights, position, shooting Flame Image, obtains radiant energy signal through image processing techniques, the theoretical and advanced solution strategies of radiant heat transfer.Because flame color image brightness is directly proportional to the radiant energy that image detector receives, when IMAQ and treatment conditions are fixed (condition that lens aperture, photography shutter, gain and white balance etc. affect image information does not change), directly can obtain relative radiation energy signal from the gray value of image, radiant energy signal initial value can be referred to as.This value can reflect furnace cavity combustion position fast, strong with the relevance of unit, but detector in use affects by coking, dust stratification, eyeglass variable color etc., and prompt radiation energy signal value there will be instability, and pulsation is large, the situation of poor reliability.On this basis, Chinese patent literature discloses a kind of method [application number: 201310301791.7] revising radiant energy static deviation, describes a kind of concrete solution, eliminates the impact of each factor on radiant energy signal accuracy to a certain extent.

In order to improve, the optimization of prompt radiation energy be calculated, better adapt to the unit of dissimilar, various capacity, and through long-term application to engineering practice, now propose a kind of up-to-date radiant energy signal and detect and building method.

Summary of the invention

The object of the invention is to propose a kind of fossil-fired unit stove combustion energy emission energy signal construction method, the radiant energy signal making it obtain has the features such as the degree of accuracy is high, applicability is strong, interference-free.

Technical scheme of the present invention is as follows:

A construction method for fossil-fired unit stove combustion energy emission energy signal, its feature comprises the steps: in method

1), along on burner hearth differing heights position many flame image detectors are installed, obtain furnace flame radiation image information, through the gray value GSU of the real-time computed image of image processing techniques _i,j, its expression formula:

GSU _i,j＝0.11R+0.59G+0.23B (1)

Wherein, i is the number of flame detector, and j is the number that each detector gathers image, often opens image and calculates a gray value; R, G, B are respectively the image three primary colors red, green, blue value of information, and define the gray value GSU of image _i,jfor prompt radiation can be worth;

2), using the reality of unit send out power and value can do dynamic range conversion, according to formula (2-3) as benchmark to prompt radiation:

$k_{1,i}=\frac{\underset{j=1}{\overset{M}{\mathrm{\Σ}}}{P}_j/{\mathrm{GSU}}_{i,j}}{M}---\left(2\right)$

E _i,M＝k _1,i·GSU _i,M(3)

Wherein, k _{1, i}be the proportionality coefficient of the prompt radiation energy signal that i-th detector obtains, M is the data long number calculating proportionality coefficient data segment, GSU _i,Mbe the number of prompt radiation energy signal in the M moment of i-th detector acquisition, E _i,Mbeing the M moment is converted to and the radiant energy value of unit load with range;

3), screening wherein correctly reflects the prompt radiation energy signal that unit load changes, according to formula (4-5):

|E _i,M-P _M|≤E _thr(4)

$E_0=\frac{\underset{i=1}{\overset{N^{\′}}{\mathrm{\Σ}}}{E}_{i,M}}{N^{\′}}(N^{\′}\≤N)---\left(5\right)$

Wherein, P _mfor the reality in corresponding M moment sends out performance number, E _thrfor the threshold value of setting, N is total detector number, and N ' is for meeting the detector number of formula (4), E ₀be the radiant energy signal average of the correct reflection energy variation after screening;

4), to the radiant energy signal E of unit at load variations acute phase ₀optimize:

$k_2=(a^{\′}+b^{\′}\·P)/(a^{\′}+b^{\′}\·\stackrel{\‾}{P})---\left(6\right)$

E＝k ₂·E ₀(7)

Wherein, k ₂be second correction factor, a', b' are k _{1, i}the coefficient that the average of random groups changed power and generated output P calculate through least square method, for generated output average, E is reacting furnace energy levels height, the radiant energy value finally exported.

The present invention, compared with relevant art, has the following advantages and the technique effect of high-lighting:

The present invention has mainly used twice proportionality coefficient correction link and a threshold values to judge link, and first time ratio correction is by the gray value of image, and namely prompt radiation value can be transformed into the identical range of power real in unit; Threshold values judges that link rejects the impact because being subject to the error message that the factor such as coking, dust stratification is brought in the running of image detector.The correction of second time ratio is that the linear relationship of foundation first correction factor and the power of the assembling unit is to eliminate the excessive or too small deviation of violent varying duty stage radiant energy signal; The radiant energy signal finally obtained is the detection signal of capacity of furnace level, when burning instruction changes, radiant energy signal can reflect timely, its value excessive or too smallly reflect combustion rate or " supply exceed demand ", " supply-less-than-demand ", and the radiant energy signal that the method builds by the impact of measurement noises, can not be transported in coordinated control system as the operational factor of unit and participate in combustion control.Therefore the method can eliminate impact too small or excessive on radiant energy correction when being elevated violent by unit load, and radiant energy signal exports the most at last.Prove through practice result, the radiant energy signal of output effectively can either reflect and turn eliminates the deviation of signal that detector dust deposition causes by the pulsating nature of furnace flame, can be applicable to the coal unit of different model, different capabilities.Good on-line checkingi means are provided to the optimal control participating in boiler combustion and unit cooperative.

Accompanying drawing explanation

Fig. 1 is flame on-line monitoring system structure chart.

Fig. 2 is radiant energy signal construction method flow chart.

Fig. 3 is that the gray value of image sends out power contrast's curve with real.

Fig. 4 is that detector C CD13 obtains image intensity value and a real power contrast, can find to occur larger error message in 9:10 and the 9:40 moment.

Fig. 5 judges primary radiation energy signal threshold values, gives the representative of in 4 layers of flame detector every layer, rejects error value by threshold values bound.

Fig. 6 is the primary radiation energy signal average after threshold values judges, the source number calculating this average is dynamic, with unit actual power power contrast, can find out both difference.

Fig. 7 a, Fig. 7 b are the prompt radiation energy signal errors in lifting load stage, less than normal, bigger than normally mark with circle in the drawings.

Fig. 8 a, Fig. 8 b are the real power contrast of final radiant energy signal and unit.

Fig. 9 a, Fig. 9 b and Fig. 9 c are respectively the application of radiant energy detection system in 200MW, 300MW, 600WM boiler, the final radiant energy signal exported and the correlation curve of a real power at one day.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described further.

A kind of fossil-fired unit stove combustion energy emission energy signal construction method provided by the invention, its concrete implementation method is as follows:

One, the flame detector be arranged in coal-burning boiler burner hearth 1 on differing heights position obtains the flame radiation image information in stove, and delivered in DVR by video acquisition system 2 and synthesize a sub-picture 3, through the rgb value of the real-time computed image of image processing techniques, it is asked to represent the gray value GSU (gray-scale-unit) of relative radiation energy signal, as expression formula:

GSU _i,j＝0.11R+0.59G+0.23B (1)

Wherein, i is the number of flame detector.J is the number that each detector gathers image, often opens image and calculates a gray value.

Two, furnace radiant energy signal is the energy reflection that fuel discharges at hearth combustion, and it is delivered in boiler circuit by the mode such as radiant heat transfer, convection heat transfer' heat-transfer by convection, and finally converts the output electric energy of generator to.So the change of radiation of burner hearth energy finally causes the change of unit generation amount, and radiation of burner hearth can be consistent with the actual power generation change direction of unit.Based on this, send out power as benchmark to the gray value GSU representing radiant energy signal using the reality of unit _i,jdo and dynamically follow the tracks of calculating, according to formula (9):

$k_{1,i}=\frac{\underset{j=1}{\overset{M}{\mathrm{\Σ}}}{P}_j/{\mathrm{GSU}}_{i,j}}{M}---\left(2\right)$

K _{1, i}be the proportionality coefficient of the prompt radiation energy signal that i-th detector obtains, M is the data long number calculating proportionality coefficient data segment, GSU _i,Mbe the numerical value of prompt radiation energy signal in the M moment of i-th detector acquisition:

E _i,M＝k _1,i·GSU _i,M(3)

E _i,Mfor the M moment is converted to and the radiant energy value of unit generation power with range;

Three, screening wherein correctly reflect unit load change primary radiation energy signal, method be by with the radiant energy signal E of unit generation power with range _i,Mpower P is sent out with current reality _mmake mathematic interpolation, as shown in the formula:

|E _i,M-P _M|≤E _thr(4)

E _thrfor setting threshold value, P _mfor the reality in corresponding M moment sends out performance number.The radiant energy signal not meeting above formula illustrates that the error message contained in picture is comparatively large, needs to reject, according to formula (5):

$E_0=\frac{\underset{i=1}{\overset{N^{\′}}{\mathrm{\Σ}}}{E}_{i,M}}{N^{\′}}(N^{\′}\≤N)---\left(5\right)$

Wherein, N is total detector number, and N ' is for meeting the detector number of formula (4), E ₀be the radiant energy signal average of the correct reflection energy variation after screening.E _thrchoose that should retain can the detector information of normal energy fluctuation in reacting furnace, again by invalid or be subject to the larger detector information of the factors such as coking and reject, play the effect of a limit error scope.What it is noted that due to combustion conditions and detector working condition is different, wherein correctly reflects that the quantity N ' of the primary radiation energy signal of capacity of furnace change is also dynamic change.

Four, when the single radiant energy signal correction of unit load change acute phase, because radiant energy value is by current measurement value and correction factor k _{1, i}product obtain.Due to radiant energy signal be subject to quantity combusted increase time, the quick-reaction capability of itself, cause radiant energy value to increase sharply, and now the power of the assembling unit is subject to the impact of the delay of steam-water heat transfer system, the comparatively radiant energy signal that gathers way is slow, the correction factor k now obtained by both mean value computation _{1, i}can be less than normal, cause radiant energy signal initial value E ₀also can be less than normal, in like manner during unit load down, radiant energy signal initial value E ₀can be bigger than normal.Therefore second ratio correction coefficient k is introduced ₂, setting for k _{1, i}the mean value of random groups changed power, uses with the linear relationship Mobile state correction of unit generation power, such as formula (6-7):

${\stackrel{\‾}{k}}_1=a^{\′}+b^{\′}\·P---\left(6\right)$

$k_2=(a^{\′}+b^{\′}\·P)/(a^{\′}+b^{\′}\·\stackrel{\‾}{P})---\left(7\right)$

Wherein, P is current time unit load value, for the load average of a period of time.

After the process of this step, the expression formula of final radiant energy signal value E is:

E＝k ₂·E ₀(8)

Embodiment:

The present invention has corresponding software and hardware support, and its concrete implementation method is as follows:

The flame detector be arranged on burner hearth differing heights position obtains the flame radiation image information in stove, and divide 4 layers with 16 flame detectors, 4 every layer are applied as example on the subcritical boiler of 300MW, and its structure as shown in Figure 1.

First arrange the parameter of CCD camera in flame detector to fix, ensure clear picture, state that again can not be saturated, drive SDK2000 video frequency collection card to complete the collection of flame radiation image.16 tunnel vision signals are synthesized a width flame radiation image by DVR and is transported to computer system.

Build the steps flow chart of radiant energy signal as shown in Figure 2.The normal flame image brightness that each detector catches represents the energy in space in face, furnace wall and the CCD angle of visual field through the Net long wave radiation energy launched, absorb, scattering arrives target surface, therefore its value has identical variation tendency with actual power power, but be subject to the impact of detector working environment and state, there will be the phenomenon of coking, dust stratification, cause the untrue of image, there is deviation in the image intensity value representing radiant energy accordingly, such as, detector C CD13 in Fig. 3.Partial enlargement Fig. 4, can clearly find to occur larger fluctuation in 9:10 and the 9:40 moment, and this causes due to detector coking, and after Jiao comes off by the time, image intensity value returns to normal value again.

Utilize correction factor one, dynamic calculation is carried out to initial gray value, complete the process of sending out power identical range real in unit.Setting threshold values E _thr=30, namely primary radiation can value when being greater than this threshold values with the real difference sending out power, and the radiant energy signal of this correspondence can disallowable, do not participate in radiant energy calculating below.As shown in Figure 5, the intermediate value judged through threshold values bound is normal signal, and the primary radiation energy signal met the demands asks its average to obtain radiant energy signal initial value, as shown in Figure 6.

When unit is at varying duty stage running, as at load up, response speed the power real in unit being subject to quantity combusted and increasing due to radiant energy signal causes first correction factor can be less than normal, thus the radiant energy initial value obtained is less than normal, and in like manner during unit load down, radiant energy initial value can be bigger than normal.As shown in circle sign in Fig. 7 a and Fig. 7 b.Utilize correction factor k under each load _{1, i}average the linear relationship of the power of the assembling unit, utilizes second correction factor k that formula (7) obtains ₂to the fine setting of radiant energy signal initial value ratio, note wherein calculating a real power average time period length can regulate according to actual effect.Finally calculate final radiant energy signal E by formula (8), result as figures 8 a and 8 b show.

The radiant energy signal built by the method correctly can reflect the change of stove combustion energy, and what its physical significance represented is the corresponding relation of working as front furnace combustion thermal discharge and power of the assembling unit energy requirement.Radiant energy computational methods of the present invention are applicable to the unit of all kinds, various capacity, as shown in Fig. 9 a, Fig. 9 b and Fig. 9 c.The difference of radiant energy signal and unit load reflects the adjustment of stove combustion and does not put in place.The difference reduced further between the two optimizes the target of boiler turbine therrmodynamic system control, is also meaning of the present invention.

Claims (1)

1. a construction method for fossil-fired unit stove combustion energy emission energy signal, its feature comprises the steps: in method

1), along on the position of burner hearth differing heights many flame image detectors are installed, obtain furnace flame radiation image information, through the gray value GSU of the real-time computed image of image processing techniques _i,j, its expression formula:

GSU _i,j＝0.11R+0.59G+0.23B (1)

Wherein, i is the number of flame detector, and j is the number that each detector gathers image, often opens image and calculates a gray value; R, G, B are respectively the image three primary colors red, green, blue value of information, and define the gray value GSU of image _i,jfor prompt radiation can be worth;

2), using the reality of unit send out power and value can do dynamic range conversion, according to formula (2-3) as benchmark to prompt radiation:

$k_{1,i}=\frac{\underset{j=1}{\overset{M}{\mathrm{\Σ}}}{P}_j/{\mathrm{GSU}}_{i,j}}{M}---\left(2\right)$

E _i,M＝k _1,i·GSU _i,M(3)

Wherein, k _{1, i}be the proportionality coefficient of the prompt radiation energy signal that i-th detector obtains, M is the data long number calculating proportionality coefficient data segment, GSU _i,Mbe the number of prompt radiation energy signal in the M moment of i-th detector acquisition, E _i,Mbeing the M moment is converted to and the radiant energy value of unit load with range;

3), screening wherein correctly reflects the prompt radiation energy signal that unit load changes, according to formula (4-5):

|E _i,M-P _M|≤E _thr(4)

$E_0=\frac{\underset{i=1}{\overset{N^{\′}}{\mathrm{\Σ}}}{E}_{i,M}}{N^{\′}},(N^{\′}\≤N)---\left(5\right)$

Wherein, P _mfor the reality in corresponding M moment sends out performance number, E _thrfor the threshold value of setting, N is total detector number, and N ' is for meeting the detector number of formula (4), E ₀be the radiant energy signal average of the correct reflection energy variation after screening;

4), to the radiant energy signal E of unit at load variations acute phase ₀optimize:

$k_2=(a^{\′}+b^{\′}\·P)/(a^{\′}+b^{\′}\·\stackrel{\‾}{P})---\left(6\right)$

E＝k ₂·E ₀(7)

Wherein, k ₂be second correction factor, a', b' are k _{1, i}the coefficient that the average of random groups changed power and generated output P calculate through least square method, for generated output average, E is reacting furnace energy levels height, the radiant energy value finally exported.