CN102213708A - Method for testing air leak rate of air preheater - Google Patents

Abstract

The invention relates to a method for testing the air leak rate of an air preheater, which is easy to implement, accurate and reliable and is suitable for analyzing and testing the air preheater. The accuracy of temperature measurement can reach 0.1 DEG C, the smoke venting temperature is within the range of between 100 and 200 DEG C approximately, and when a boiler runs stably, the smoke venting temperature is constant basically, so the relative accuracy of the temperature measurement is higher than the analytic accuracy of the oxygen content of smoke. Therefore the air leak rate, which is calculated according to the change of the smoke venting temperature, of the air preheater has the higher test accuracy. The method comprises the following steps of: 1) measuring the smoke venting temperature theta py of the air preheater and the temperature TKin of air entering the air preheater; and 2) utilizing a formula, namely when the change of the air leak rate is needed to be monitored due to the change of the air leak rate with the change of the running condition or equipment condition of the air preheater, measuring the air temperature TKin and the smoke venting temperature thetapy in the running state, which corresponds to the temperature thetapy, of the boiler, and calculating the air leak rate AL by the formula.

Description

The method of testing of air-heater leakage rate

Technical field

The present invention relates to a kind of method of testing of air-heater leakage rate.

Background technology

Air preheater (abbreviation air preheater) is the visual plant of large-sized boiler.In air preheater, flue gas is to the transfer of air heat, and temperature reduces after the flue gas heat release, leaves the smoke evacuation that air preheater becomes boiler.Large-sized station boiler generally adopts rotary regenerative air preheater, and heat accumulating element is with certain speed rotation, periodically with flue gas and air heat exchange.Because rotatablely moving of heat accumulating element (rotor) needs certain dynamic and static gaps in the rotary regenerative air preheater, and flue gas is in negative pressure state in rotary regenerative air preheater, and air is in barotropic state, therefore, has bleed flue gas and discharge air preheater with flue gas of portion of air.Air preheater is the percent that air leak rate of air curtain is meant the air duty gas primary heater inlet flue gas of the flue gas that bleeds.The air leak rate of air curtain of rotary regenerative air preheater is to estimate the important indicator of primary heater performance.When air leak rate of air curtain is excessive, give, the load of induced draft fan increases, and has a strong impact on the normal operation of boiler.

The air leak rate of air curtain method of testing that generally adopts is that air leak rate of air curtain is calculated in the smoke components variation (oxygen content, carbon dioxide content etc.) that detects the air preheater import and export at present.This method of testing is implemented comparatively complicated, needs special instrument, and fluctuating range in boiler operatiopn such as (as oxygen level) may be bigger because smoke components, thereby running status is had strict requirement, and this also has influence on precision of test result.Because the in-line meter of flue gas oxygen content has certain measurement to lag behind, bring bigger error sometimes with on-the-spot in-line meter estimation air leak rate of air curtain.In addition, the resolution of analysis of oxygen content instrument is generally 0.1% oxygen content, and the oxygen level of flue gas is generally about 5%～7%, so the relative accuracy of oxygen content measurement is about 2%, and this also has influence on the measuring accuracy of air-heater leakage rate.

Summary of the invention

Purpose of the present invention provides a kind of method of testing of air-heater leakage rate exactly for addressing the above problem, and this method is mainly calculated the air leak rate of air curtain of air preheater according to the variation of the outlet temperature (being exhaust gas temperature) of air preheater.This method is easy to implement, accurately and reliably, is fit to air preheater is carried out analytical test.Because thermometric accuracy can reach 0.1 ℃, and the scope of exhaust gas temperature is roughly between 100 ℃ to 200 ℃, and when boiler operatiopn was stablized, exhaust gas temperature was also constant substantially, so thermometric relative accuracy is wanted to reach 0.1%, is much higher than the analysis precision of flue gas oxygen content.Thereby the air leak rate of air curtain of calculating air preheater according to the variation of exhaust gas temperature has higher measuring accuracy.

For achieving the above object, the present invention adopts following technical scheme:

A kind of method of testing of air-heater leakage rate, its step is:

1) measures air preheater exhaust gas temperature θ _PyWith the air themperature TK that enters air preheater _In

2) utilize formula $\frac{m_l}{m_y}=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{C_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}---\left(2\right)$

In the formula,

Be the air leak rate of air curtain of air preheater, specific heat C _kAnd C _yGet by fitting that formula calculates or looking into by chart,

It is the ratio of flue gas specific heat and air specific heat;

m _l, m _yBe respectively by air preheater the bleed air quality of flue gas and the flue gas quality that enters air preheater;

C _kAir is at temperature T K _InTo temperature θ _PyBetween mean specific heat;

C _yFlue gas is at temperature θ _PyTo temperature θ _{0, py}Between mean specific heat;

θ _PyBe actual exhaust gas temperature, comprise the influence of leaking out;

TK _InIt is the air themperature that enters air preheater;

θ _{0, py}It is the exhaust gas temperature when supposing not leak out;

When air preheater operation conditions or status of equipment change, air leak rate of air curtain changes thereupon, when needing the variation of monitoring air leak rate of air curtain, as long as make boiler be in θ _{0, py}Under the pairing running status, by measuring air themperature TK _InWith exhaust gas temperature θ _Py, can calculate air leak rate of air curtain A by (2) _L

Described θ _{0, py}Be the exhaust gas temperature when supposing not leak out, when other condition is all constant except that air leak rate of air curtain, θ _{0, py}Remain unchanged; Determine θ _{0, py}The time according to taking following step:

At first determine the boiler operatiopn state, promptly boiler under rated load, move and major pant item also at the operating condition of conventional state, this state is exactly the state of analysis of after this leaking out; Enter the flue-gas temperature θ of air preheater this moment _KySubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure this moment also be air leak rate of air curtain A under the original state _L0, again by the θ under (3) formula calculating corresponding states _{0, py}

${\mathrm{\θ}}_{0,\mathrm{py}}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{C_y}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{\mathrm{\α}}---\left(3\right)$

Under the actual state, consider exhaust gas temperature except that the influence that is subjected to leaking out, also be subjected to the influence of inlet air temperature; For this reason, need be converted to the calculating of leaking out again under the standard inlet air temperature (or environment temperature) to exhaust gas temperature, the reduction formula of exhaust gas temperature is as follows:

${\mathrm{\θ}}_{\mathrm{py}}^b=\frac{{\mathrm{TK}}_0({\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{\θ}}_{\mathrm{py}})+{\mathrm{\θ}}_{\mathrm{ky}}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{{\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{TK}}_{\mathrm{in}}}---\left(4\right)$

In the formula,

For the air preheater inlet air temperature is TK ₀The time exhaust gas temperature;

TK ₀Being air preheater standard inlet air temperature or environment temperature, is 20 ℃;

TK _InEnter the air themperature (or environment temperature) of air preheater when being actual measurement;

θ _PyBe the exhaust gas temperature of actual measurement, with TK _InCorresponding;

θ _KyIt is the temperature that enters the flue gas of air preheater;

Converse the exhaust gas temperature under the standard inlet temperature (or environment temperature) Afterwards, utilize (5) formula can draw the exhaust gas temperature of under standard temperature, supposing under the situation of not leaking out again

${\mathrm{\θ}}_{0,\mathrm{py}}^b={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{C_y}={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{\mathrm{\α}}---\left(5\right);$

Change in equipment state, when needing the current air-heater leakage rate of measuring and calculating, equipment is maintained definite running status, the test exhaust gas temperature, and converse exhaust gas temperature under the corresponding assurance temperature by (4) formula

Calculate current air leak rate of air curtain according to (6) formula again.

$A_L=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{C_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{{\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0}---\left(6\right)$

Test philosophy of the present invention is as follows:

The 1 thermal equilibrium relation of leaking out

Leaking out is entered fume side and is finally left air preheater in fume side by the primary heater air side, becomes the some of smoke evacuation.Leaking out becomes smoke evacuation by cold wind, and no matter its position that enters flue gas is in which zone of air preheater, and its temperature variation all is that the cold wind temperature when entering air preheater is warming up to the exhaust gas temperature of flue gas when leaving air preheater.Because heating has also mixed this partly air that leaks out, the exhaust gas temperature ratio is low when not leaking out fully, and Here it is leaks out to the influence of exhaust gas temperature.According to the above analysis, can calculate the exhaust gas temperature when not leaking out fully and the influence of size of leaking out to exhaust gas temperature.

(1) formula has been described the influence of leaking out to exhaust gas temperature.

m _lC _k(θ _py-TK _in)＝m _yC _y(θ _0，py-θ _py) (1)

In the formula, m _l, m _yBe respectively by air preheater the bleed air quality of flue gas and the flue gas quality that enters air preheater;

C _kAir is at temperature T K _InTo temperature θ _PyBetween mean specific heat;

C _yFlue gas is at temperature θ _PyTo temperature θ _{0, py}Between mean specific heat;

θ _PyBe actual exhaust gas temperature, comprise the influence of leaking out;

TK _InIt is the air themperature that enters air preheater;

θ _{0, py}It is the exhaust gas temperature when supposing not leak out.

By (1) formula as can be known,

$\frac{m_l}{m_y}=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{C_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}---\left(2\right)$

In the formula, Be the air leak rate of air curtain of air preheater.Specific heat C _kAnd C _yCan get by fitting that formula calculates or looking into by chart,

It is the ratio of flue gas specific heat and air specific heat.

By (2) formula, at known θ _{0, py}Situation under, by measuring exhaust gas temperature θ _Py, enter the air themperature TK of air preheater _InJust the air leak rate of air curtain of air preheater can have been calculated.

2 θ _{0, py}Determine

θ _{0, py}Be the exhaust gas temperature when supposing not leak out, when other condition is all constant except that air leak rate of air curtain, θ _{0, py}Remain unchanged.Determine θ _{0, py}Can be according to taking following step:

At first determine certain boiler operatiopn state, generally be boiler under rated load, move and major pant item also at the operating condition of conventional state, this state is exactly the state that after this leaks out and analyze, and enters the flue-gas temperature θ of air preheater at this moment _KySubstantially constant.Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and measures the air leak rate of air curtain A of this moment (also can be called under the original state) by other method (as the fume component analysis method) _L0, again by the θ under (3) formula calculating corresponding states _{0, py}

${\mathrm{\θ}}_{0,\mathrm{py}}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{C_y}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{\mathrm{\α}}---\left(3\right)$

3 test air leak rate of air curtain A _L

When air preheater operation conditions or status of equipment change, air leak rate of air curtain may change thereupon, when needing the variation of monitoring air leak rate of air curtain, as long as make boiler be in θ _{0, py}Under the pairing running status, by measuring air themperature TK _InWith exhaust gas temperature θ _Py, can calculate air leak rate of air curtain A by (2) _L

Under actual state, exhaust gas temperature also is subjected to the influence of inlet air temperature influencing except that being subjected to leaking out.Therefore, need be converted to the calculating of leaking out again under the certain standard inlet air temperature (or environment temperature) to exhaust gas temperature.The reduction formula of exhaust gas temperature is as follows:

${\mathrm{\θ}}_{\mathrm{py}}^b=\frac{{\mathrm{TK}}_0({\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{\θ}}_{\mathrm{py}})+{\mathrm{\θ}}_{\mathrm{ky}}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{{\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{TK}}_{\mathrm{in}}}---\left(4\right)$

In the formula,

For the air preheater inlet air temperature is TK ₀The time exhaust gas temperature;

TK ₀Be air preheater standard inlet air temperature (or environment temperature), generally be chosen as 20 ℃;

TK _InEnter the air themperature (or environment temperature) of air preheater when being actual measurement;

θ _PyBe the exhaust gas temperature of actual measurement, with TK _InCorresponding.

θ _KyIt is the temperature that enters the flue gas of air preheater.

Converse the exhaust gas temperature under the standard temperature Afterwards, utilize (5) formula can draw the exhaust gas temperature of under standard temperature, supposing under the situation of not leaking out again

${\mathrm{\θ}}_{0,\mathrm{py}}^b={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{C_y}={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{\mathrm{\α}}---\left(5\right)$

Obtain by the practical application step of exhaust gas temperature change calculations air-heater leakage rate by above-mentioned analysis be:

1 under the state of determining, test exhaust gas temperature and corresponding original state air leak rate of air curtain converse the exhaust gas temperature under the corresponding assurance temperature

2 change in equipment state, when needing the current air-heater leakage rate of measuring and calculating, equipment are maintained definite running status, the test exhaust gas temperature, and converse exhaust gas temperature under the corresponding assurance temperature by (4) formula

Calculate current air leak rate of air curtain according to (6) formula again.

$A_L=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{C_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{{\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0}---\left(6\right)$

The invention has the beneficial effects as follows: easy to implement, measure accurately, make things convenient for the boiler operatiopn monitoring.

Because the thermometry maturation, instrument is reliable, and easy operating is easier to implement so use method of the present invention; And during stable operation of the boiler, flue-gas temperature is also highly stable, adds that temperature survey has very high accuracy, and this makes this method measurement result more accurately and reliably.The temperature monitoring instrument of large-sized boiler is all comparatively complete, and the reliability of thermometric instrument and accuracy all are better than the in-line meter of flue gas oxygen amount, and this method provides new approach for utilizing online thermometric instrument monitoring equipment situation.Computational data when table 1 is imported and exported flue gas oxygen content change calculations air leak rate of air curtain for utilizing air preheater, because the resolution of gas analysis instrument is the oxygen level of 0.1% (absolute value), when the flue gas oxygen content of measuring changes 0.1%, the air leak rate of air curtain results change 0.6%.Here it is analysis of oxygen content accuracy of instrument is to the situation that influences of accuracy of measurement.Also explanation in like manner: under this state,, will cause 0.6% measurement result change if there is 0.1% flue gas oxygen content fluctuation in the boiler operatiopn.Table 2 calculates the data of air leak rate of air curtain for utilizing method of the present invention, and when 0.1 ℃ variation took place exhaust gas temperature, air leak rate of air curtain had changed 0.1%.Comparison sheet 1 and table 2 as seen, method of the present invention can reflect the variation of equipment state better, the degree of accuracy height, antijamming capability is strong.

Table 1 utilizes flue gas oxygen content change calculations air preheater air leak rate of air curtain

Table 2 utilizes method of the present invention to calculate the air preheater air leak rate of air curtain

Embodiment

The present invention will be further described below in conjunction with embodiment.

A kind of method of testing of air-heater leakage rate, its step is:

1) measures air preheater exhaust gas temperature θ _PyWith the air themperature TK that enters air preheater _In

2) utilize formula $\frac{m_l}{m_y}=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{C_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}---\left(2\right)$

In the formula,

Be the air leak rate of air curtain of air preheater, specific heat C _kAnd C _yGet by fitting that formula calculates or looking into by chart,

It is the ratio of flue gas specific heat and air specific heat;

m _l, m _yBe respectively by air preheater the bleed air quality of flue gas and the flue gas quality that enters air preheater;

C _kAir is at temperature T K _InTo temperature θ _PyBetween mean specific heat;

C _yFlue gas is at temperature θ _PyTo temperature θ _{0, py}Between mean specific heat;

θ _PyBe actual exhaust gas temperature, comprise the influence of leaking out;

TK _InIt is the air themperature that enters air preheater;

θ _{0, py}It is the exhaust gas temperature when supposing not leak out;

3) change when air preheater operation conditions or status of equipment, air leak rate of air curtain changes thereupon, when needing the variation of monitoring air leak rate of air curtain, as long as make boiler be in θ _{0, py}Under the pairing running status, by measuring air themperature TK _InWith exhaust gas temperature θ _Py, can calculate air leak rate of air curtain A by (2) _L

Described θ _{0, py}Be the exhaust gas temperature when supposing not leak out, when other condition is all constant except that air leak rate of air curtain, θ _{0, py}Remain unchanged; Determine θ _{0, py}The time according to taking following step:

At first determine the boiler operatiopn state, promptly boiler under rated load, move and major pant item also at the operating condition of conventional state, this state is exactly the state of analysis of after this leaking out; Enter the flue-gas temperature θ of air preheater this moment _KySubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure this moment also be air leak rate of air curtain A under the original state _L0, again by the θ under (3) formula calculating corresponding states _{0, py}

${\mathrm{\θ}}_{0,\mathrm{py}}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{C_y}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{\mathrm{\α}}---\left(3\right)$

Under the actual state, consider exhaust gas temperature except that the influence that is subjected to leaking out, also be subjected to the influence of inlet air temperature; For this reason, need be converted to the calculating of leaking out again under the standard inlet air temperature (or environment temperature) to exhaust gas temperature, the reduction formula of exhaust gas temperature is as follows:

${\mathrm{\θ}}_{\mathrm{py}}^b=\frac{{\mathrm{TK}}_0({\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{\θ}}_{\mathrm{py}})+{\mathrm{\θ}}_{\mathrm{ky}}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{{\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{TK}}_{\mathrm{in}}}---\left(4\right)$

In the formula,

For the air preheater inlet air temperature is TK ₀The time exhaust gas temperature;

TK ₀Being air preheater standard inlet air temperature (or environment temperature), is 20 ℃;

TK _InEnter the air themperature or the environment temperature of air preheater when being actual measurement;

θ _PyBe the exhaust gas temperature of actual measurement, with TK _InCorresponding;

θ _KyIt is the temperature that enters the flue gas of air preheater;

Converse the exhaust gas temperature under the standard inlet air temperature (or environment temperature)

Afterwards, utilize (5) formula can draw the exhaust gas temperature of under standard temperature, supposing under the situation of not leaking out again

${\mathrm{\θ}}_{0,\mathrm{py}}^b={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{C_y}={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{\mathrm{\α}}---\left(5\right)$

Change in equipment state, when needing the current air-heater leakage rate of measuring and calculating, equipment is maintained definite running status, the test exhaust gas temperature, and converse exhaust gas temperature under the corresponding assurance temperature by (4) formula

Calculate current air leak rate of air curtain according to (6) formula again.

$A_L=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{C_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{{\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0}---\left(6\right)$

In this example, original state is as follows:

The exhaust gas temperature that is calculated under the standard ambient temperature (20 ℃) by (4) formula is 138.15 ℃, the exhaust gas temperature when being calculated supposition and do not leaked out by (5) formula again It is 144.58 ℃.

When status of equipment changes, in the time of need testing air leak rate of air curtain once more, make equipment operation condition be stabilized in the operating condition of preliminary examination state correspondence once more, the measurement result of this moment is as follows:

16.0 ℃ of environment temperatures

134.9 ℃ of exhaust gas temperatures

The exhaust gas temperature that is calculated under the standard ambient temperature (20 ℃) by (4) formula is 137.43 ℃, again by (6) formula with obtained

The air leak rate of air curtain that value calculates this moment is 6.3%.

In this calculating, the value of α is taken as 1.03.When the α value changes, Result of calculation small variation is arranged, but final air leak rate of air curtain result of calculation is almost constant, this adaptability that these computing method also are described is good, the result is stable.

Claims (3)

1. the method for testing of an air-heater leakage rate is characterized in that, its step is:

1) measures air preheater exhaust gas temperature θ _PyWith the air themperature TK that enters air preheater _In

2) utilize formula $\frac{m_l}{m_y}=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{C_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}-{\mathrm{\θ}}_{\mathrm{py}})}{({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}---\left(2\right)$

In the formula,

Be the air leak rate of air curtain of air preheater, specific heat C _kAnd C _yGet by fitting that formula calculates or looking into by chart,

It is the ratio of flue gas specific heat and air specific heat;

m _l, m _yBe respectively by air preheater the bleed air quality of flue gas and the flue gas quality that enters air preheater;

C _kAir is at temperature T K _InTo temperature θ _PyBetween mean specific heat;

C _yFlue gas is at temperature θ _PyTo temperature θ _{0, py}Between mean specific heat;

θ _PyBe actual exhaust gas temperature, comprise the influence of leaking out;

TK _InIt is the air themperature that enters air preheater;

θ _{0, py}It is the exhaust gas temperature when supposing not leak out;

When air preheater operation conditions or status of equipment change, air leak rate of air curtain changes thereupon, when needing the variation of monitoring air leak rate of air curtain, as long as make boiler be in θ _{0, py}Under the pairing running status, by measuring air themperature TK _InWith exhaust gas temperature θ _Py, can calculate air leak rate of air curtain A by (2) _L

2. the method for testing of air-heater leakage rate as claimed in claim 1 is characterized in that, described θ _{0, py}Be the exhaust gas temperature when supposing not leak out, when other condition is all constant except that air leak rate of air curtain, θ _{0, py}Remain unchanged; Determine θ _{0, py}The time according to taking following step:

At first determine the boiler operatiopn state, promptly boiler under rated load, move and major pant item also at the operating condition of conventional state, this state is exactly the state of analysis of after this leaking out; Enter the flue-gas temperature θ of air preheater this moment _KySubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure this moment also be air leak rate of air curtain A under the original state _L0, again by the θ under (3) formula calculating corresponding states _{0, py}

${\mathrm{\θ}}_{0,\mathrm{py}}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{C_y}={\mathrm{\θ}}_{\mathrm{py}}+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{\mathrm{\α}}---\left(3\right)$

3. the method for testing of air-heater leakage rate as claimed in claim 1 is characterized in that, under the actual state, considers exhaust gas temperature except that the influence that is subjected to leaking out, and also is subjected to the influence of inlet air temperature; For this reason, need be converted to the calculating of leaking out again under the standard temperature to exhaust gas temperature, the reduction formula of exhaust gas temperature is as follows:

${\mathrm{\θ}}_{\mathrm{py}}^b=\frac{{\mathrm{TK}}_0({\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{\θ}}_{\mathrm{py}})+{\mathrm{\θ}}_{\mathrm{ky}}({\mathrm{\θ}}_{\mathrm{py}}-{\mathrm{TK}}_{\mathrm{in}})}{{\mathrm{\θ}}_{\mathrm{ky}}-{\mathrm{TK}}_{\mathrm{in}}}---\left(4\right)$

In the formula, For the air preheater inlet air temperature is TK ₀The time exhaust gas temperature;

TK ₀Being air preheater standard inlet air temperature (or environment temperature), is 20 ℃;

TK _InEnter the air themperature or the environment temperature of air preheater when being actual measurement;

θ _PyBe the exhaust gas temperature of actual measurement, with TK _InCorresponding;

θ _KyIt is the temperature that enters the flue gas of air preheater;

Converse the exhaust gas temperature under the standard inlet air temperature (or environment temperature)

Afterwards, utilize (5) formula can draw the exhaust gas temperature of under standard temperature, supposing under the situation of not leaking out again

${\mathrm{\θ}}_{0,\mathrm{py}}^b={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}{C}_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{C_y}={\mathrm{\θ}}_{\mathrm{py}}^b+\frac{A_{L0}({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}{\mathrm{\α}}---\left(5\right)$

Change in equipment state, when needing the current air-heater leakage rate of measuring and calculating, equipment is maintained definite running status, the test exhaust gas temperature, and converse exhaust gas temperature under the corresponding assurance temperature by (4) formula Calculate current air leak rate of air curtain according to (6) formula again

$A_L=\frac{C_y({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{C_k({\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0)}=\frac{\mathrm{\α}({\mathrm{\θ}}_{0,\mathrm{py}}^b-{\mathrm{\θ}}_{\mathrm{py}}^b)}{{\mathrm{\θ}}_{\mathrm{py}}^b-{\mathrm{TK}}_0}---\left(6\right).$