CN101697179A - Method for measuring and calculating trend of heat value of fuel coal of power station boiler based on positive and negative heat balance relationship - Google Patents

Abstract

The invention relates to a method for measuring and calculating the calorific value trend of coal-fired power plant boilers based on the relationship of positive and negative heat balance. The trend curve of coal calorific value changing with time realizes the monitoring of the changing trend of coal calorific value. In the coal-fired calorific value calculation method, first use the real-time database of the plant-level monitoring information system to read relevant parameters, and assume the coal-fired calorific value at a certain moment, substitute it into the boiler inverse equilibrium efficiency model, calculate the boiler thermal efficiency, and then use Boiler positive balance efficiency model, using the effective use of heat by the boiler, the amount of fuel in the furnace and the calculated boiler thermal efficiency to obtain the current coal-fired calorific value, and iteratively corrects the current coal-fired calorific value by judging the deviation of the coal-fired calorific value before and after, and finally Determine the calculated value of the calorific value of coal combustion at this moment. The method is simple to calculate, low in cost and wide in adaptability, and can well realize the online trend analysis of the calorific value of coal combustion.

Description

Fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation

Technical field

The present invention relates to a kind of fuel coal of power station boiler calorific value trend measuring method, particularly be furnished with the fuel coal of power station boiler calorific value trend measuring method of unit pulverized-coal system based on positive and negative thermal equilibrium relation.

Background technology

At present, the generating plant mainly is to obtain by the off-line sample examination to the monitoring of coal-fired calorific value, the technical analysis of ature of coal exists bigger sample preparation sum of errors and lags behind serious analysis time, the how variation of the coal-fired calorific value of online sign, and then improve the optimal control and the stability of burning, then be the problem that people are concerned about always.

The appearance of online ash content, water analysis instrument, at some typical ature of coal, set up relation between coal-fired calorific value and moisture, the ash content by means such as statistical study, regretional analyses, realized the on-line measurement of coal-fired calorific value, but because the analyser apparatus expensive, domestic has application at the minority coal industry.

Chinese patent 02110116.7 discloses a kind of stove ature of coal method of real-time of going into, this method is utilized fume component analysis, the thermal balance equation of coal pulverizer, the dry ash-free basis of each elemental composition of simultaneous iterative such as correlationship empirical equation between combustion chemistry equation and each coal elements content, and then realized real-time monitoring to coal-fired calorific value by Mendeleev's formula, applied it to simultaneously in the genset of 300MW, obtained good effect, yet the measurand that this method relates to is too much, the solution procedure relative complex, coal-fired calorific value monitoring accuracy only depends on the accuracy that each coal elements composition is found the solution, in addition, correlationship between the individual element content is to obtain by the statistical study to some typical ature of coal, has certain limitation.

Also having a kind of technology in addition is according to the different running statuses of boiler, related information between relevant operational factor and coal-fired calorific value, simulate the formation and the accumulative process of expertise experience by the thought of data statistics in the data mining technology and self study, expert's procedure knowledge that coal-fired calorific value changes is predicted in online generation, this is a kind of new online soft diagnostic method of the coal-fired calorific value of stove of going into, for the burning adjusting and the optimal control of boiler provides new approaches, but problems affect such as the imperfection of data statistics and self study deficiency the prediction that coal-fired calorific value changes, and await to study further.

Summary of the invention

The object of the present invention is to provide a kind of fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation, this method can be good at the variation tendency of the coal-fired calorific value of online reflection.

The present invention adopts following technical scheme:

Using coal-fired calorific value measuring method, is preface with the time order and function, obtain respectively τ=t, t+ Δ t, t+2 Δ t ..., inscribe corresponding coal-fired calorific value measuring and calculating value Q during t+n Δ t _Dt ^y, Q _{D (t+ Δ t)} ^y, Q _{D (t+2 Δ t)} ^y..., Q _{D (t+n Δ t)} ^y, and draw out coal-fired calorific value measuring and calculating value Q _{D τ} ^yTime dependent trend curve,

The concrete operations step of described coal-fired calorific value measuring method is as follows:

Step 1: at τ constantly, suppose an initial coal-fired calorific value Q _D1 ^y, the wind pushing temperature t that inscribes when utilizing the real-time data base of plant level supervisory information system (SIS) to read this _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, go into stove fuel quantity B, boiler capacity D, unit generation load Pel, main steam pressure p _GrAnd temperature t _Gr, reheated steam intake pressure p _ZrjAnd temperature t _Zrj, reheated steam top hole pressure p _ZrcAnd temperature t _Zrc, feed pressure p _Gs, feed temperature t _Gs, feedwater flow D _Gs, drum pressure p _Qb, reheater desuperheat injection flow rate D _Zrjw, and hot colder section at different levels of steam turbine draw gas, the pressure and temperature of condensate water and hydrophobic correspondence,

Step 2: according to the coal-fired calorific value Q of step 1 acquisition _D1 ^y, wind pushing temperature t _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, boiler capacity D, utilize the anti-balance efficiency model of boiler, calculate boiler thermal output η _{B is anti-},

Step 3: according to the boiler thermal output η of step 2 acquisition _{B is anti-}, step 1 read go into stove fuel quantity B and use other to read the boiler that calculation of parameter draws and effectively utilize hot Q ₁, utilize boiler positive balance efficiency model, obtain corresponding current coal-fired calorific value Q _D2 ^y,

Step 4: if (Q _D1 ^y-Q _D2 ^y) absolute value greater than given small quantity ε, then with current coal-fired calorific value Q _D2 ^yAssignment is given coal-fired calorific value Q _D1 ^y, repeating step 2～4 is up to (Q _D1 ^y-Q _D2 ^y) absolute value be less than or equal to given small quantity ε, with current coal-fired calorific value Q _D2 ^yThe coal-fired calorific value Q that inscribes during as τ _{D τ} ^y, described ε determines according to predetermined precision.

The anti-balance efficiency model of above-mentioned boiler is:

η _{B is anti-}=100-(L _Uc+ L _g+ L _m+ L _CO+ L _r+ L _Un) (1)

$L_{\mathrm{uc}}=\frac{337.27}{Q_{d1}^y}\·A^y\·(r_{\mathrm{fh}}\·\frac{C_{\mathrm{fh}}}{100-C_{\mathrm{fh}}}+r_{\mathrm{lz}}\·\frac{C_{\mathrm{lz}}}{100-C_{\mathrm{lz}}})\·100\%---\left(2\right)$

$L_g=\frac{C_{\mathrm{ph}}}{Q_{d1}^y}\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(3\right)$

$L_m=\frac{C_{p{H}_{2}O}}{Q_{d1}^y}\&CenterDot;[k_3+0.01\&times;({\mathrm{<figure-callout\; id="4"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_4+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})]\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(4\right)$

$L_r=5.82\&CenterDot;{\left(D_e\right)}^{-0.38}\&CenterDot;\frac{D_e}{D}\&CenterDot;100\%---\left(5\right)$

${\mathrm{\&alpha;}}_{\mathrm{py}}=\frac{21}{21-{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}_{2\mathrm{py}}}---\left(6\right)$

${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=0.0576+0.02337\&CenterDot;\frac{Q_{d1}^y}{1000},{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=0.58145+0.30806\&CenterDot;\frac{Q_{d1}^y}{1000}$

$k_3=0.90809-0.0163\&CenterDot;\frac{Q_{d1}^y}{1000},{\mathrm{<figure-callout\; id="4"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_4=-0.0139+0.0089\&CenterDot;\frac{Q_{d1}^y}{1000}$

In the formula: L _Uc--for not burning the thermal loss of carbon in total dry ash amount,

L _g--be the dry gas loss,

L _m--be the moisture thermal loss,

L _CO--be the imperfect combustion thermal loss of chemistry.When using solid fuel, the imperfect combustion product of gas has only carbon monoxide, and the carbon monoxide content in the smoke evacuation is seldom, thus can ignore,

L _r--be radiation loss,

L _Un--be other thermal loss, generally be taken as 0.33～0.38%,

A _y--be the as received basis ash content, select for use design load to get final product,

r _Fh, r _Lz--be respectively the grey share that accounts for into the total ash amount of stove coal of measuring in flying dust, the slag, generally get r _Fh=0.9, r _Lz=0.1,

C _Fh, C _Lz--be respectively unburned carbon in flue dust, boiler slag carbon content, when having ready conditions, available measured value; When unconditional, or based on the actual measurement and the real time data of history, set up unburned carbon in flue dust, boiler slag carbon content regression model respectively, i.e. C with generation load and smoke evacuation oxygen quantitative changeization _Fh=f ₁(Pel, O _2py), C _Lz=f ₂(Pel, O _2py); Or the unburned carbon in flue dust of analysis of history and boiler slag carbon content data, set up the regression model that boiler slag carbon content changes with unburned carbon in flue dust, i.e. C _Fh=f (C _Lz),

C _Pg--be the level pressure mean specific heat of dry flue gas, this value can be simplified and is taken as 1.03kJ/ (kg.K),

O _2py--for smoke evacuation oxygen amount, adopt measured value,

α _Py--be excess air coefficient, this is worth available smoke evacuation oxygen amount O _2pySimplification is tried to achieve, and sees formula (6),

The oxygen amount of wherein discharging fume adopts measured value,

t _Py, t _Lk--be respectively exhaust gas temperature and cold air temperature, adopt measured value,

--be the level pressure mean specific heat of water vapour, this value can be simplified and is taken as 1.88kJ/ (kg.K),

D _e, D--is respectively boiler rating and the real-time evaporation capacity of boiler, the latter adopts measured value,

k ₁, k ₂, k ₃, k ₄--be the function about fuel value, the DIN standard of atlas and Germany of calculating according to German thermal engineering is tried to achieve.

Q _D1 ^y--be fuel value.

Above-mentioned boiler effectively utilizes hot Q ₁Be calculated as follows:

Q ₁＝D _gr·(i″ _gr-i _gs)+D _zr·(i″ _zr-i′ _zr)+D _pw·(i′-i _gs) (7)

In the formula: D _Gr-superheater outlet steam flow, the measured value of the real-time evaporation capacity D of employing boiler,

D _Zr--reheater outlet steam flow, D _Zr=A _Zr* D _Gr+ D _Zrjw, wherein, A _ZrBe the reheated steam share, according to the steam turbine that from SIS system real-time data base, reads hot colder section at different levelsly draw gas, the pressure and temperature of condensate water and hydrophobic correspondence, its share A that draws gas by the high temperature heater (HTH) heat Balance Calculation ₁And A ₂And then, by A _Zr=1-A ₁-A ₂Calculate the reheated steam share, in addition, D _ZrjwBe reheater desuperheat injection flow rate, adopt measured value,

D _Pw--blowdown flow, for subcritical dum boiler, take blowdown share A according to the boiler design book _PwFor super critical boiler, get A _Pw=0; And then, by D _Pw=A _Pw* D _GrCalculate blowdown flow,

I " _Gr, i ' _Zr, i " _Zr, i _Gs, i '--be respectively superheated vapor enthalpy, reheated steam and import and export enthalpy, feedwater enthalpy and drum pressure saturation water enthalpy down, its value utilizes the water vapour chart to obtain according to temperature, pressure measuring value accordingly.

Above-mentioned boiler positive balance efficiency model is as follows:

In the formula: B--is that boiler is gone into the stove fuel quantity, adopts measured value,

Q ₁--for boiler effectively utilizes heat,

η _{B is anti-}--be the anti-balance efficiency of boiler.

The invention has the advantages that:

1, compare with coal-fired calorific value measuring method in the past, this method lays particular emphasis on the coal-fired calorific value trend analysis of satisfying under the boiler heat balance relation.In each coal-fired calorific value measuring and calculating process constantly, all the positive and negative balance thermal efficiency of boiler model is united, obtain the coal-fired calorific value measuring and calculating value of inscribing when corresponding, thereby when difference, inscribe, the difference that calculates between the coal-fired calorific value based on same thermal equilibrium relation can reflect coal-fired calorific value trend over time truly, exactly.

2, as a kind of flexible measurement method, the required parameter of coal-fired calorific value measuring and calculating process all directly reads from the real-time data base of plant level supervisory information system (SIS), the on-the-spot expensive utility appliance such as extra increase analysis or measurement instrument that do not need, only need to increase corresponding software module in existing SIS system and get final product, cost is low.

3, in coal-fired calorific value measuring and calculating process, by the coal-fired calorific value initial value of supposition, only the positive and negative balance thermal efficiency model to boiler carries out iterative, wherein these two models are explicit equation, do not relate to simultaneous solution to the implicit equation group, calculate easy, fast convergence rate.

4, some coal-fired calorific value measuring method need be by means of the incidence relation between coal elemental composition, thereby only is applicable to specific ature of coal.The measuring method of this coal-fired calorific value need not with reference to the incidence relation between the coal elemental composition, only need satisfy the thermal equilibrium relation of boiler, thereby can calculate the coal-fired calorific value of different coals, and applicability is wide.

5, it can be loaded in the performance monitoring module, be used to instruct the burning adjusting and the optimal control of boiler, improve the performance on-line monitoring system of whole unit further, in extensive range, the convenience of its expanded application.

Description of drawings

Fig. 1 is coal-fired calorific value trend measuring and calculating process flow diagram.

Fig. 2 is the time dependent trend curve of coal-fired calorific value.

Embodiment

Using coal-fired calorific value measuring method, is preface with the time order and function, obtain respectively τ=t, t+ Δ t, t+2 Δ t ..., inscribe corresponding coal-fired calorific value measuring and calculating value Q during t+n Δ t _Dt ^y, Q _{D (t+ Δ t)} ^y, Q _{D (t+2 Δ t)} ^y..., Q _{D (t+n Δ t)} ^y, and draw out coal-fired calorific value measuring and calculating value Q _{D τ} ^yTime dependent trend curve,

The concrete operations step of described coal-fired calorific value measuring method is as follows:

Step 1: at τ constantly, suppose an initial coal-fired calorific value Q _D1 ^y, the wind pushing temperature t that inscribes when utilizing the real-time data base of plant level supervisory information system (SIS) to read this _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, go into stove fuel quantity B, boiler capacity D, unit generation load Pel, main steam pressure p _GrAnd temperature t _Gr, reheated steam intake pressure p _ZrjAnd temperature t _Zrj, reheated steam top hole pressure p _ZrcAnd temperature t _Zrc, feed pressure p _Gs, feed temperature t _Gs, feedwater flow D _Gs, drum pressure p _Qb, reheater desuperheat injection flow rate D _Zrjw, and hot colder section at different levels of steam turbine draw gas, the pressure and temperature of condensate water and hydrophobic correspondence,

Step 2: according to the coal-fired calorific value Q of step 1 acquisition _D1 ^y, wind pushing temperature t _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, boiler capacity D, utilize the anti-balance efficiency model of boiler, calculate boiler thermal output η _{B is anti-},

Step 3: according to the boiler thermal output η of step 2 acquisition _{B is anti-}, step 1 read go into stove fuel quantity B and use other to read the boiler that calculation of parameter draws and effectively utilize hot Q ₁, utilize boiler positive balance efficiency model, obtain corresponding current coal-fired calorific value Q _D2 ^y,

Step 4: if (Q _D1 ^y-Q _D2 ^y) absolute value greater than given small quantity ε, then with current coal-fired calorific value Q _D2 ^yAssignment is given coal-fired calorific value Q _D1 ^y, repeating step 2～4 is up to (Q _D1 ^y-Q _D2 ^y) absolute value be less than or equal to given small quantity ε, with current coal-fired calorific value Q _D2 ^yThe coal-fired calorific value Q that inscribes during as τ _{D τ} ^y, described ε can be set in according to precision within 0.001 to 0.1 the scope.

The anti-balance efficiency model of above-mentioned boiler is ASME (PTC4.1) criterion calculation that adopts the U.S. generally, wherein calculates atlas and German DIN standard with reference to German thermal engineering for convenience's sake when calculating dry flue gas amount and vapour content; Because when the thermal loss (radiation loss) that gauging surface radiation and convection current cause, it is fair curve that the ASME standard adopts, the loss of calculating is bigger than normal substantially, therefore calculates with reference to station boiler performance test rules GB10184-88 in addition.The boiler efficiency model of this simplification is as follows:

η _{B is anti-}=100-(L _Uc+ L _g+ L _m+ L _CO+ L _r+ L _Un) (1)

$L_{\mathrm{uc}}=\frac{337.27}{Q_{d1}^y}\&CenterDot;A^y\&CenterDot;(r_{\mathrm{fh}}\&CenterDot;\frac{C_{\mathrm{fh}}}{100-C_{\mathrm{fh}}}+r_{\mathrm{lz}}\&CenterDot;\frac{C_{\mathrm{lz}}}{100-C_{\mathrm{lz}}})\&CenterDot;100\%---\left(2\right)$

$L_g=\frac{C_{\mathrm{ph}}}{Q_{d1}^y}\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(3\right)$

$L_m=\frac{C_{p{H}_{2}O}}{Q_{d1}^y}\&CenterDot;[k_3+0.01\&times;({\mathrm{<figure-callout\; id="4"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_4+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})]\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(4\right)$

$L_r=5.82\&CenterDot;{\left(D_e\right)}^{-0.38}\&CenterDot;\frac{D_e}{D}\&CenterDot;100\%---\left(5\right)$

${\mathrm{\&alpha;}}_{\mathrm{py}}=\frac{21}{21-{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}_{2\mathrm{py}}}---\left(6\right)$

${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=0.0576+0.02337\&CenterDot;\frac{Q_{d1}^y}{1000},{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=0.58145+0.30806\&CenterDot;\frac{Q_{d1}^y}{1000}$

$k_3=0.90809-0.0163\&CenterDot;\frac{Q_{d1}^y}{1000},{\mathrm{<figure-callout\; id="4"\; label="k"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_4=-0.0139+0.0089\&CenterDot;\frac{Q_{d1}^y}{1000}$

In the formula: L _Uc--for not burning the thermal loss of carbon in total dry ash amount,

L _g--be the dry gas loss,

L _m--be the moisture thermal loss,

L _CO--be the imperfect combustion thermal loss of chemistry.When using solid fuel, the imperfect combustion product of gas has only carbon monoxide, and the carbon monoxide content in the smoke evacuation is seldom, thus can ignore,

L _r--be radiation loss,

L _Un--be other thermal loss, generally be taken as 0.33～0.38%,

A _y--be the as received basis ash content, select for use design load to get final product,

r _Fh, r _Lz--be respectively the grey share that accounts for into the total ash amount of stove coal of measuring in flying dust, the slag, generally get r _Fh=0.9, r _Lz=0.1,

C _Fh, C _Lz--be respectively unburned carbon in flue dust, boiler slag carbon content, when having ready conditions, available measured value; When unconditional, or based on the actual measurement and the real time data of history, set up unburned carbon in flue dust, boiler slag carbon content regression model respectively, i.e. C with generation load and smoke evacuation oxygen quantitative changeization _Fh=f ₁(Pel, O _2py), C _Lz=f ₂(Pel, O _2py); Or the unburned carbon in flue dust of analysis of history and boiler slag carbon content data, set up the regression model that boiler slag carbon content changes with unburned carbon in flue dust, i.e. C _Fh=f (C _Lz),

C _Pg--be the level pressure mean specific heat of dry flue gas, this value can be simplified and is taken as 1.03kJ/ (kg.K),

O _2py--for smoke evacuation oxygen amount, adopt measured value,

α _Py--be excess air coefficient, this is worth available smoke evacuation oxygen amount O _2pySimplification is tried to achieve, and sees formula (6), and the oxygen amount of wherein discharging fume adopts measured value,

t _Py, t _Lk--be respectively exhaust gas temperature and cold air temperature, adopt measured value,

--be the level pressure mean specific heat of water vapour, this value can be simplified and is taken as 1.88kJ/ (kg.K),

D _e, D--is respectively boiler rating and the real-time evaporation capacity of boiler, the latter adopts measured value, k ₁, k ₂, k ₃, k ₄--be the function about fuel value, the DIN standard of atlas and Germany of calculating according to German thermal engineering is tried to achieve.

Q _D1 ^y--be fuel value.

Above-mentioned boiler effectively utilizes hot Q ₁Be calculated as follows:

Q ₁＝D _gr·(i″ _gr-i _gs)+D _zr·(i″ _zr-i′ _zr)+D _pw·(i-i _gs) (7)

In the formula: D _Gr--superheater outlet steam flow, the measured value of the real-time evaporation capacity D of employing boiler,

D _Zr--reheater outlet steam flow, D _Zr=A _Zr* D _Gr+ D _Zrjw, wherein, A _ZrBe the reheated steam share, according to the steam turbine that from SIS system real-time data base, reads hot colder section at different levelsly draw gas, the pressure and temperature of condensate water and hydrophobic correspondence, its share A that draws gas by the high temperature heater (HTH) heat Balance Calculation ₁And A ₂And then, by A _Zr=1-A ₁-A ₂Calculate the reheated steam share, in addition, D _ZrjwBe reheater desuperheat injection flow rate, adopt measured value,

D _Pw--blowdown flow, for subcritical dum boiler, take blowdown share A according to the boiler design book _PwFor super critical boiler, get A _Pw=0; And then, by D _Pw=A _Pw* D _GrCalculate blowdown flow,

I " _Gr, i ' _Zr, i " _Zr, i _Gs, i '--be respectively superheated vapor enthalpy, reheated steam and import and export enthalpy, feedwater enthalpy and drum pressure saturation water enthalpy down, its value utilizes the water vapour chart to obtain according to temperature, pressure measuring value accordingly.

Above-mentioned boiler positive balance efficiency model is:

In the formula: the B--boiler is gone into the stove fuel quantity, adopts measured value,

Q ₁--for boiler effectively utilizes heat,

η _{B is anti-}--be the anti-balance efficiency of boiler.

With the 600MW genset is example, realizes the fuel coal of power station boiler calorific value trend measuring and calculating based on positive and negative thermal equilibrium relation.It is B﹠amp that this 600MW unit is furnished with a model; Overcritical, the single reheat Control Circulation drum boiler of WB-1950/25.41-M and three cylinders, four steam discharges, single shaft, the condensing turbine that model is CLN600-24.2/538/566; Boiler is a unit pulverized-coal system, is furnished with six ZGM113N type medium-speed pulverizers.

Detailed step based on the fuel coal of power station boiler calorific value trend measuring method of positive and negative thermal equilibrium relation is as follows:

1., from the real-time data base of plant level supervisory information system (SIS), read relevant real time data, as under τ=t operating condition constantly, main real time data is as follows:

2 wind pushing temperature t _LkBe respectively 29.2,28.4 ℃;

8 exhaust gas temperature t _PyBe respectively 151.75,141.07,128.07,117.28,108.25,115.53,127.03,148.28 ℃;

4 smoke evacuation oxygen amount O _2pyBe respectively 3.21,2.57,3.58,3.95%;

2 unburned carbon in flue dust C _FhBe respectively 0.23,0.31%;

The exerting oneself of 6 coal pulverizer A, B, C, D, E, F is respectively 48.5,39.8,38.1,43.9,44.5,40t/h, and the stove fuel quantity B that goes into that it is total is 254.8t/h;

2 boiler capacity D are 1778.03,1778.07t/h;

Unit generation load Pel is 615MW;

3 main steam pressure p _GrBe 23.79,23.75,23.75Mpa;

3 main steam temperature t _GrIt is 541.5,541.6,539.8 ℃;

Reheated steam intake pressure p _ZrjBe 4.18Mpa;

Reheated steam inlet temperature t _ZrjIt is 295.4 ℃;

2 reheated steam top hole pressure p _ZrcBe respectively 3.94,3.95Mpa;

2 reheated steam outlet temperature t _ZrcBe respectively 568.2,569.5 ℃;

3 feed pressure p _GsBe respectively 27.38,27.33,27.34Mpa;

2 feed temperature t _GsBe respectively 272.58,274.4 ℃;

Feedwater flow D _GsBe 1890.5t/h;

2 drum pressure p _QbBe 25.30,25.22Mpa;

Reheated steam desuperheat injection flow rate is 10.71t/h;

And hot colder section at different levels of steam turbine draw gas, the pressure and temperature of condensate water and hydrophobic correspondence.

2., according to the steam turbine that reads in 1. hot colder section at different levelsly draw gas, the pressure and temperature of condensate water and hydrophobic correspondence, obtain corresponding enthalpy, and by the high temperature heater (HTH) heat Balance Calculation its share A that draws gas ₁And A ₂, and then by A _Zr=1-A ₁-A ₂Calculate the reheated steam share, then according to real-time evaporation capacity D of boiler and reheated steam desuperheat injection flow rate D _Zrjw, utilize formula D _Zr=A _Zr* D+D _ZrjwCalculate reheated steam flow D _Zr

3., according to the main steam that reads in 1., reheated steam import and export, pressure, the temperature of feedwater draw corresponding enthalpy, that utilizes that formula (7) calculates boiler effectively utilizes hot Q ₁,, thereby get blowdown flow D wherein because the boiler that this unit is furnished with is postcritical _Pw=0.

4., suppose coal-fired calorific value Q _D1 ^yInitial value be 10000kJ/kg.

5., with coal-fired calorific value Q _D1 ^yReach column data down: wind pushing temperature t _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, in the real-time evaporation capacity D of boiler substitution boiler counter-balance thermal efficiency modular form (1)～(6), obtain boiler counter-balance thermal efficiency η _{B is anti-}, boiler slag carbon content C wherein _LzBe C according to the historical actual measurement of this factory _LzWith corresponding Pel and O _2py, by setting up its random groups generation load Pel and smoke evacuation oxygen amount O _2pyThe regression model that changes obtains, and regression model is:

$C_{\mathrm{lz}}=-24.84+37.57\&CenterDot;\frac{\mathrm{Pel}}{P}+7.36\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}_{2\mathrm{py}}-11.18\&CenterDot;{\left(\frac{\mathrm{Pel}}{P}\right)}^2-0.49\&CenterDot;{{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}_{2\mathrm{py}}}^2-4.58\&CenterDot;\frac{\mathrm{Pel}}{P}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101853551E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}_{2\mathrm{py}}$

Wherein P is specified unit generation load 600MW.

That 6., utilize stove fuel quantity B, boiler effectively utilizes hot Q ₁And the boiler counter-balance thermal efficiency η that 5. calculates _{B is anti-},, obtain coal-fired calorific value Q by boiler positive balance thermal efficiency modular form (8) _D2 ^y

7., judge (Q _D1 ^y-Q _D2 ^y) absolute value whether smaller or equal to given small quantity ε=0.01kJ/kg, if (Q _D1 ^y-Q _D2 ^y) absolute value smaller or equal to ε, then calculate to finish Q _D2 ^yThe coal-fired calorific value Q that inscribes when being τ=t _Dt ^yIf (Q _D1 ^y-Q _D2 ^y) absolute value greater than ε, then with Q _D2 ^yAssignment is given Q _D1 ^y, repeating step 5.～7..According to step 1.～7., through 7 iteration, the coal-fired calorific value Q that inscribes when final measuring and calculating draws τ=t _Dt ^yBe 19663kJ/kg.

8., arbitrarily access time interval of delta t=10min, measuring and calculating τ=t plays one day coal-fired calorific value variation tendency constantly, each constantly t+ Δ t, t+2 Δ t ..., under the t+144 Δ t, 1.～7. repeating step inscribes corresponding coal-fired calorific value Q when calculating each _{D (t+ Δ t)} ^y, Q _{D (t+2 Δ t)} ^y..., Q _{D (t+144 Δ t)} ^y

9., draw coal-fired calorific value Q _{D τ} ^yTime dependent trend curve.

Claims (4)

1. fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation, it is characterized in that, using coal-fired calorific value measuring method, is preface with the time order and function, obtain respectively τ=t, t+ Δ t, t+2 Δ t ..., inscribe corresponding coal-fired calorific value measuring and calculating value Q during t+n Δ t _Dt ^y, Q _{D (t+ Δ t)} ^y, Q _{D (t+2 Δ t)} ^y..., Q _{D (t+n Δ t)} ^y, and draw out coal-fired calorific value measuring and calculating value Q _{D τ} ^yTime dependent trend curve,

The concrete operations step of described coal-fired calorific value measuring method is as follows:

Step 1: at τ constantly, suppose an initial coal-fired calorific value Q _D1 ^y, the wind pushing temperature t that inscribes when utilizing the real-time data base of plant level supervisory information system (SIS) to read this _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount Q _2py, unburned carbon in flue dust C _Fh, go into stove fuel quantity B, boiler capacity D, unit generation load Pel, main steam pressure P _GrAnd temperature t _Gr, reheated steam intake pressure P _ZrjAnd temperature t _Zrj, reheated steam top hole pressure P _ZrcAnd temperature t _Zrc, feed pressure p _Gs, feed temperature t _Gs, feedwater flow D _Gs, drum pressure p _Qb, reheater desuperheat injection flow rate D _Zrjw, and hot colder section at different levels of steam turbine draw gas, the pressure and temperature of condensate water and hydrophobic correspondence,

Step 2: according to the coal-fired calorific value Q of step 1 acquisition _D1 ^y, wind pushing temperature t _Lk, exhaust gas temperature t _Py, smoke evacuation oxygen amount O _2py, unburned carbon in flue dust C _Fh, boiler capacity D, utilize the anti-balance efficiency model of boiler, calculate boiler thermal output η _{B is anti-},

Step 3: according to the boiler thermal output η of step 2 acquisition _{B is anti-}, step 1 read go into stove fuel quantity B and use other to read the boiler that calculation of parameter draws and effectively utilize hot Q ₁, utilize boiler positive balance efficiency model, obtain corresponding current coal-fired calorific value Q _D2 ^y,

Step 4: if (Q _D1 ^y-Q _D2 ^y) absolute value greater than given small quantity ε, then with current coal-fired calorific value Q _D2 ^yAssignment is given coal-fired calorific value Q _D1 ^y, repeating step 2～4 is up to (Q _D1 ^y-Q _D2 ^y) absolute value be less than or equal to given small quantity ε, with current coal-fired calorific value Q _D2 ^yThe coal-fired calorific value Q that inscribes during as τ _{D τ} ^y, described ε determines according to predetermined precision.

2. the fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation according to claim 1 is characterized in that the anti-balance efficiency model of above-mentioned boiler is:

η _{B is anti-}=100-(L _Uc+ L _g+ L _m+ L _CO+ L _r+ L _Un) (1)

$L_{\mathrm{uc}}=\frac{337.27}{Q_{d1}^y}\&CenterDot;A^y\&CenterDot;(r_{\mathrm{fh}}\&CenterDot;\frac{C_{\mathrm{fh}}}{100-C_{\mathrm{fh}}}+r_{\mathrm{lz}}\&CenterDot;\frac{C_{\mathrm{lz}}}{100-C_{\mathrm{lz}}})\&CenterDot;100\%---\left(2\right)$

$L_g=\frac{C_{\mathrm{pg}}}{Q_{d1}^y}\&CenterDot;(k_1+k_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(3\right)$

$L_m=\frac{C_{p{H}_{2}O}}{Q_{d1}^y}\&CenterDot;[k_3+0.01\&times;(k_4+k_2\&CenterDot;{\mathrm{\&alpha;}}_{\mathrm{py}})]\&CenterDot;(t_{\mathrm{py}}-t_{\mathrm{lk}})\&CenterDot;100\%---\left(4\right)$

$L_r=5.82\&CenterDot;{\left(D_e\right)}^{-0.38}\&CenterDot;\frac{D_e}{D}\&CenterDot;100\%---\left(5\right)$

${\mathrm{\&alpha;}}_{\mathrm{py}}=\frac{21}{21-O_{2\mathrm{py}}}---\left(6\right)$

$k_1=0.0576+0.02337\&CenterDot;\frac{Q_{d1}^y}{1000}$ $k_2=0.58145+0.30806\&CenterDot;\frac{Q_{d1}^y}{1000}$

$k_3=0.90809-0.0163\&CenterDot;\frac{Q_{d1}^y}{1000}$ $k_4=-0.0139+0.0089\&CenterDot;\frac{Q_{d1}^y}{1000}$

In the formula: L _Uc--for not burning the thermal loss of carbon in total dry ash amount,

L _g--be the dry gas loss,

L _m--be the moisture thermal loss,

L _CO--be the imperfect combustion thermal loss of chemistry.When using solid fuel, the imperfect combustion product of gas has only carbon monoxide, and the carbon monoxide content in the smoke evacuation is seldom, thus can ignore,

L _r--be radiation loss,

L _Un--be other thermal loss, generally be taken as 0.33～0.38%,

A _y--be the as received basis ash content, select for use design load to get final product,

r _Fh, r _Lz--be respectively the grey share that accounts for into the total ash amount of stove coal of measuring in flying dust, the slag, generally get r _Fh=0.9, r _Lz=0.1,

C _Fh, C _Lz--be respectively unburned carbon in flue dust, boiler slag carbon content, when having ready conditions, available measured value; When unconditional, or based on the actual measurement and the real time data of history, set up unburned carbon in flue dust, boiler slag carbon content regression model respectively, i.e. C with generation load and smoke evacuation oxygen quantitative changeization _Fh=f ₁(Pel, O _2py), C _Lz=f ₂(Pel, Q _2py); Or the unburned carbon in flue dust of analysis of history and boiler slag carbon content data, set up the regression model that boiler slag carbon content changes with unburned carbon in flue dust, i.e. C _Fh=f (C _Lz),

C _Pg--be the level pressure mean specific heat of dry flue gas, this value can be simplified and is taken as 1.03kJ/ (kg.K),

O _2py--for smoke evacuation oxygen amount, adopt measured value,

α _Py--be excess air coefficient, this is worth available smoke evacuation oxygen amount O _2pySimplification is tried to achieve, and sees formula (6), and the oxygen amount of wherein discharging fume adopts measured value,

t _Py, t _Lk--be respectively exhaust gas temperature and cold air temperature, adopt measured value,

--be the level pressure mean specific heat of water vapour, this value can be simplified and is taken as 1.88kJ/ (kg.K),

D _e, D--is respectively boiler rating and the real-time evaporation capacity of boiler, the latter adopts measured value,

k ₁, k ₂, k ₃, k ₄--be the function about fuel value, the DIN standard of atlas and Germany of calculating according to German thermal engineering is tried to achieve.

Q _D1 ^y--be fuel value.

3. the fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation according to claim 1 is characterized in that above-mentioned boiler effectively utilizes hot Q ₁Be calculated as follows:

Q ₁＝D _gr·(i″ _gr-i _gs)+D _zr·(i″ _zr-i′ _zr)+D _pw·(i′-i _gs) (7)

In the formula: D _Gr--superheater outlet steam flow, the measured value of the real-time evaporation capacity D of employing boiler,

D _Zr--reheater outlet steam flow, D _Zr=A _Zr* D _Gr+ D _Zrjw, wherein, A _ZrBe the reheated steam share, according to the steam turbine that from SIS system real-time data base, reads hot colder section at different levelsly draw gas, the pressure and temperature of condensate water and hydrophobic correspondence, its share A that draws gas by the high temperature heater (HTH) heat Balance Calculation ₁And A ₂And then, by A _Zr=1-A ₁-A ₂Calculate the reheated steam share, in addition, D _ZrjwBe reheater desuperheat injection flow rate, adopt measured value,

D _Pw--blowdown flow, for subcritical dum boiler, take blowdown share A according to the boiler design book _PwFor super critical boiler, get A _Pw=0; And then, by D _Pw=A _Pw* D _GrCalculate blowdown flow,

I " _Gr, i ' _Zr, i " _Zr, i _Gs, i '--be respectively superheated vapor enthalpy, reheated steam and import and export enthalpy, feedwater enthalpy and drum pressure saturation water enthalpy down, its value utilizes the water vapour chart to obtain according to temperature, pressure measuring value accordingly.

4. the fuel coal of power station boiler calorific value trend measuring method based on positive and negative thermal equilibrium relation according to claim 1 is characterized in that above-mentioned boiler positive balance efficiency model is as follows:

In the formula: B--is that boiler is gone into the stove fuel quantity, adopts measured value,

Q ₁--for boiler effectively utilizes heat,

η _{B is anti-}--be the anti-balance efficiency of boiler.

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