CN102213708B - 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 leak rate of air preheater

Technical field

The present invention relates to a kind of method of testing of air leak rate of air preheater.

Background technology

Air preheater (abbreviation air preheater) is the visual plant of large-sized boiler.In air preheater, flue gas is to transfer of air heat, and after flue gas heat release, temperature reduces, and 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 in rotary regenerative air preheater (rotor) needs certain dynamic and static gaps, and flue gas is in negative pressure state in rotary regenerative air preheater, and air is in barotropic state, therefore, have bleed flue gas discharge air preheater with flue gas of portion of air.Air preheater is the percent that air leak rate of air curtain refers to the air duty air preheater inlet flue gas of the flue gas that bleeds.The air leak rate of air curtain of rotary regenerative air preheater is to evaluate 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 generally adopting is at present that air leak rate of air curtain is calculated in the smoke components variation (oxygen content, carbon dioxide content etc.) that detects air preheater import and export.This method of testing is implemented comparatively complicated, needs special instrument, and because the fluctuating range of smoke components (as oxygen level etc.) in boiler operatiopn may be larger, thereby running status is had to strict requirement, this also has influence on the accuracy of test result.Because the in-line meter of flue gas oxygen content has certain measurement to lag behind, by on-the-spot in-line meter estimation air leak rate of air curtain, bring sometimes larger error.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 in 5%～7% left and right, so the relative accuracy of oxygen content measurement is in 2% left and right, and this also has influence on the measuring accuracy of air leak rate of air preheater.

Summary of the invention

Object of the present invention, exactly for addressing the above problem, provides a kind of method of testing of air leak rate of air preheater, and the air leak rate of air curtain of air preheater is calculated in the variation of the outlet temperature of the method Main Basis air preheater (being exhaust gas temperature).The method is easy to implement, accurately and reliably, is applicable to air preheater to carry 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 is stablized, exhaust gas temperature is also substantially constant, 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 method of testing for air leak rate of air preheater, its step is:

1) measure 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 formula,

be the air leak rate of air curtain of air preheater, specific heat C _kand C _yby fitting formula, calculate or look into and get 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 impact of leaking out;

TK _init is the air themperature that enters air preheater;

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

When air preheater operation conditions or status of equipment change, air leak rate of air curtain changes thereupon, in the time of need to monitoring the variation of air leak rate of air curtain, as long as make boiler in θ _{0, py}under corresponding running status, by measuring air themperature TK _inwith exhaust gas temperature θ _py, by (2), can calculate air leak rate of air curtain A _l.

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

First determine boiler operatiopn state, 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; Now enter the flue-gas temperature θ of air preheater _kysubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure be also now the air leak rate of air curtain A under original state _l0, then calculate the θ under corresponding states by (3) formula _{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 actual state, consider exhaust gas temperature and leak out impact except being subject to, be also subject to the impact of inlet air temperature; For this reason, exhaust gas temperature need to be converted to the calculating of leaking out again under standard inlet air temperature (or environment 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 formula,

for air preheater inlet air temperature is TK ₀time exhaust gas temperature;

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

TK _inwhile being actual measurement, enter the air themperature (or environment temperature) of air preheater;

θ _pythe 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 standard inlet temperature (or environment temperature)

afterwards, recycling (5) formula can draw the exhaust gas temperature that hypothesis is not leaked out in situation under standard temperature

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

In equipment state, change, in the time of need to calculating current air leak rate of air preheater, equipment is maintained to definite running status, test exhaust gas temperature, and converse the exhaust gas temperature at corresponding assurance temperature by (4) formula according to (6) formula, calculate current air leak rate of air curtain 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

Leak out and enter fume side and finally in fume side, leave air preheater by primary heater air side, become the some of smoke evacuation.Leak out and become smoke evacuation by cold wind, no matter it enters which region of the position of flue gas in air preheater, and its temperature variation is all the exhaust gas temperature of the cold wind temperature when entering air preheater when being warming up to flue gas and leaving air preheater.Because heat and mixed this part air that leaks out, exhaust gas temperature ratio is lower while not leaking out completely, the impact that Here it is leaks out on exhaust gas temperature.According to the above analysis, can calculate the exhaust gas temperature while not leaking out completely and leak out the impact of size on exhaust gas temperature.

(1) formula has been described the impact of leaking out on exhaust gas temperature.

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

In 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 impact of leaking out;

TK _init is the air themperature that enters air preheater;

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

From (1) 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 formula,

be the air leak rate of air curtain of air preheater.Specific heat C _kand C _ycan calculate or look into and get by chart by fitting formula,

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

First determine certain boiler operatiopn state, be generally 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, and now enters the flue-gas temperature θ of air preheater _kysubstantially constant.Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and measures now the air leak rate of air curtain A of (also can be called under original state) by other method (as fume component analysis method) _l0, then calculate the θ under corresponding states by (3) formula _{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, in the time of need to monitoring the variation of air leak rate of air curtain, as long as make boiler in θ _{0, py}under corresponding running status, by measuring air themperature TK _inwith exhaust gas temperature θ _py, by (2), can calculate air leak rate of air curtain A _l.

Under actual state, exhaust gas temperature leaks out impact except being subject to, and is also subject to the impact of inlet air temperature.Therefore, exhaust gas temperature need to be converted to the calculating of leaking out again under certain standard inlet air temperature (or environment 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 formula, for air preheater inlet air temperature is TK ₀time exhaust gas temperature;

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

TK _inwhile being actual measurement, enter the air themperature (or environment temperature) of air preheater;

θ _pythe 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 standard temperature

afterwards, recycling (5) formula can draw the exhaust gas temperature that hypothesis is not leaked out in situation under standard temperature

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

By above-mentioned analysis, obtained by the practical application step of exhaust gas temperature change calculations air leak rate of air preheater be:

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

2 change in equipment state, in the time of need to calculating current air leak rate of air preheater, equipment are maintained to definite running status, test exhaust gas temperature, and converse the exhaust gas temperature at corresponding assurance temperature by (4) formula

according to (6) formula, calculate current air leak rate of air curtain 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, facilitate boiler operatiopn monitoring.

Because thermometry is ripe, instrument is reliable, and easy operating is easier to implement so apply method of the present invention; And during stable operation of the boiler, flue-gas temperature is also highly stable, add that temperature survey has very high accuracy, 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 are all better than the in-line meter of Oxygen Amount in Flue Gas, and this method is for utilizing online thermometric instrument monitoring equipment situation that new approach is provided.Table 1 is the computational data while utilizing air preheater to import and export flue gas oxygen content change calculations air leak rate of air curtain, 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%, air leak rate of air curtain results change 0.6%.The affect situation of analysis of oxygen content accuracy of instrument on accuracy of measurement that Here it is.In like manner also explanation: under this state, if there is 0.1% flue gas oxygen content fluctuation in boiler operatiopn, by the measurement result change that causes 0.6%.Table 2 is for utilizing method of the present invention to calculate the data of air leak rate of air curtain, and when the variation of 0.1 ℃ occurs exhaust gas temperature, air leak rate of air curtain has changed 0.1%.Comparison sheet 1 and table 2 are visible, and method of the present invention can reflect the variation of equipment state better, and degree of accuracy is high, and antijamming capability is strong.

Table 1 utilizes flue gas oxygen content change calculations air preheater air leakage rate

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

Embodiment

Below in conjunction with embodiment, the present invention will be further described.

A method of testing for air leak rate of air preheater, its step is:

1) measure 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 formula,

be the air leak rate of air curtain of air preheater, specific heat C _kand C _yby fitting formula, calculate or look into and get 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 impact of leaking out;

TK _init is the air themperature that enters air preheater;

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

3) when air preheater operation conditions or status of equipment change, air leak rate of air curtain changes thereupon, in the time of need to monitoring the variation of air leak rate of air curtain, as long as make boiler in θ _{0, py}under corresponding running status, by measuring air themperature TK _inwith exhaust gas temperature θ _py, by (2), can calculate air leak rate of air curtain A _l.

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

First determine boiler operatiopn state, 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; Now enter the flue-gas temperature θ of air preheater _kysubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure be also now the air leak rate of air curtain A under original state _l0, then calculate the θ under corresponding states by (3) formula _{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 actual state, consider exhaust gas temperature and leak out impact except being subject to, be also subject to the impact of inlet air temperature; For this reason, exhaust gas temperature need to be converted to the calculating of leaking out again under standard inlet air temperature (or environment 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 formula,

for air preheater inlet air temperature is TK ₀time exhaust gas temperature;

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

TK _inwhile being actual measurement, enter air themperature or the environment temperature of air preheater;

θ _pythe 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 standard inlet air temperature (or environment temperature)

afterwards, recycling (5) formula can draw the exhaust gas temperature that hypothesis is not leaked out in situation under standard temperature

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

In equipment state, change, in the time of need to calculating current air leak rate of air preheater, equipment is maintained to definite running status, test exhaust gas temperature, and converse the exhaust gas temperature at corresponding assurance temperature by (4) formula

according to (6) formula, calculate current air leak rate of air curtain 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 being calculated under standard ambient temperature (20 ℃) by (4) formula is 138.15 ℃, then the exhaust gas temperature when being calculated supposition and do not leaked out by (5) formula

it is 144.58 ℃.

When status of equipment changes, in the time of need to again testing air leak rate of air curtain, make equipment operation condition again be stabilized in the operating condition that preliminary examination state is corresponding, measurement result is now as follows:

16.0 ℃ of environment temperatures

134.9 ℃ of exhaust gas temperatures

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

the air leak rate of air curtain that value calculates is now 6.3%.

In this calculating, the value of α is taken as 1.03.When α value changes,

result of calculation have small variation, but final air leak rate of air curtain result of calculation is almost constant, this adaptability that these computing method are also described is good, result is stable.

Claims (1)

1. a method of testing for air leak rate of air preheater, is characterized in that, its step is:

1) measure 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 formula,

be the air leak rate of air curtain of air preheater, specific heat C _kand C _yby fitting formula, calculate or look into and get 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 impact of leaking out;

TK _init is the air themperature that enters air preheater;

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

When air preheater operation conditions or status of equipment change, air leak rate of air curtain changes thereupon, in the time of need to monitoring the variation of air leak rate of air curtain, as long as make boiler in θ _{0, py}under corresponding running status, by measuring air themperature TK _inwith exhaust gas temperature θ _py, by (2), can calculate air leak rate of air curtain A _l;

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

First determine boiler operatiopn state, 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; Now enter the flue-gas temperature θ of air preheater _kysubstantially constant; Under this state, test enters the exhaust gas temperature of air preheater air themperature and air preheater, and to measure be also now the air leak rate of air curtain A under original state _l0, then calculate the θ under corresponding states by (3) formula _{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 actual state, consider exhaust gas temperature and leak out impact except being subject to, be also subject to the impact of inlet air temperature; For this reason, exhaust gas temperature need to be converted to the calculating of leaking out again under standard 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 formula,

for air preheater inlet air temperature is TK ₀time exhaust gas temperature;

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

TK _inwhile being actual measurement, enter air themperature or the environment temperature of air preheater;

θ _pythe 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 standard inlet air temperature or environment temperature

afterwards, recycling (5) formula can draw the exhaust gas temperature that hypothesis is not leaked out in situation under standard temperature

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

In equipment state, change, in the time of need to calculating current air leak rate of air preheater, equipment is maintained to definite running status, test exhaust gas temperature, and converse the exhaust gas temperature at corresponding assurance temperature by (4) formula according to (6) formula, calculate current air leak rate of air curtain again

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