CN103984853B - Modification method of the air leak rate of air preheater to exhaust gas temperature - Google Patents

Abstract

The present invention relates to a kind of modification method of air leak rate of air preheater to exhaust gas temperature, including step has：(1) establishing method condition；Inlet temperature is air preheater inlet temperature, while leaked-in air temperature is calculated with air preheater entrance inlet temperature；(2) draw the heat balance relational expression between fume side and air side；(3) determine air leak rate of air curtain formula；Air leak rate of air curtain is ratio of the air quality with the flue gas mass into the flue for leaking into air preheater fume side；(4) arrange formula；(5) θ ' that will be obtained_pyRevised exhaust gas temperature value is used for the corrected Calculation of boiler efficiency.The present invention derives calculating formula by air preheater thermal balance and mass balance equation, carries out exhaust gas temperature amendment with air leak rate of air preheater design load, such that it is able to quantitatively draw impact that air leak rate of air preheater is calculated to boiler efficiency.

Description

Modification method of the air leak rate of air preheater to exhaust gas temperature

Technical field

The invention belongs to power system engineering measuring technology field, especially a kind of air leak rate of air preheater are arranged to boiler The modification method of cigarette temperature.

Background technology

A very important problem in always power plant's operation of leaking out of station boiler, Air Leakage Into Boilers problem is to economy Impact it is increasing.And as the strength of materials is not high or installation and repairing technique is unqualified and the long term wear of air preheater Etc. reason, air preheater can be produced often and be leaked out.As the size of air leak rate of air curtain can be to exhaust gas temperature and smoke evacuation volume Impact, and then affect the calculating of boiler efficiency, but《Station boiler performance test code》GB10184-88 (abbreviation GB Standard) in be not provided with by design modification method of the air leak rate of air curtain to boiler efficiency value of calculation.Can cause after air leak rate of air curtain increase The illusion that exhaust gas temperature is reduced, qualitative analyses not can determine that exhaust gas temperature after reducing increasing with excess air coefficient to exhaust gas heat loss The final influence degree lost.

The content of the invention

The purpose of the present invention is, for the deficiencies in the prior art, and to propose a kind of air leak rate of air preheater to boiler exhaust gas The modification method of temperature.

The present invention solves its technical problem and takes technical scheme below to realize：

A kind of modification method of air leak rate of air preheater to exhaust gas temperature, including step is as follows：

(1) establishing method condition；Analysis is calculated for convenience, assumes initially that the qualificationss of method are：Inlet temperature is Air preheater inlet temperature, while leaked-in air temperature is calculated with air preheater entrance inlet temperature；

(2) draw the heat balance relational expression between fume side and air side；Show that relational expression is：

In formula：θ_py-- actual exhaust gas temperature, DEG C；

θ′_py-- exhaust gas temperature after amendment, DEG C；

t₀-- inlet temperature, DEG C；

Δ m-- is actual to leak into air capacity, kg；

Δ m ' -- it is adapted to design air leak rate of air curtain and leaks into air capacity, kg；

m_y-- into the flue gas mass of boiler flue, kg；

-- air is from 0 DEG C of temperature and to t0 DEG C, 0 DEG C and to θ_pyDEG C, 0 DEG C and arrive θ′_pyDEG C average specific heat at constant pressure hold, kJ/ (kgK)；

-- flue gas is from 0 DEG C of temperature and to θ_pyDEG C, 0 DEG C and arrive θ '_pyDEG C average specific heat at constant pressure hold, kJ/(kg·K)；

(3) determine air leak rate of air curtain formula；Air leak rate of air curtain is to leak into the air quality of air preheater fume side and enter boiler smoke The ratio of the flue gas mass in road, i.e.,：

(4) arrange formula (A)；Substituted according to the value of the air leak rate of air curtain and specific heat capacity that determine, obtained after arranging (A) formula：

In formula：A_L-- actual air leak rate of air curtain, %；

A′_L-- the air leak rate of air curtain under design air leakage coefficient, %；

(5) θ ' that will be obtained_pyRevised exhaust gas temperature value is used for the corrected Calculation of boiler efficiency.

And, θ in (A) formula in the step (2)_pyWith θ '_pySpecific heat capacity take identical value, i.e.,With Value is WithValue is

Advantages of the present invention and good effect are：

The present invention derives calculating formula by air preheater thermal balance and mass balance equation, leaks with air preheater Wind rate design load carries out exhaust gas temperature amendment, such that it is able to quantitatively draw shadow that air leak rate of air preheater is calculated to boiler efficiency Ring.

Description of the drawings

Fig. 1 is the actual situation of leaking out of air preheater, and air temperature is t₀, exhaust gas temperature is θ_py, leak into fume side Schematic diagram of the air quality for Δ m；

Fig. 2 is situation of leaking out under air preheater design air leakage coefficient, and air temperature is t₀, exhaust gas temperature is θ '_py, to Fume side leaks into the schematic diagram that air quality is Δ m '；

Fig. 3 is that the actual air preheater situation of leaking out is decomposed into two processes, and first process is cigarette lateral from air Gas side leakage enters the air capacity of Δ m ', and second process is the air capacities for leaking into more Δ m- Δ m ' after the air capacity for leaking into Δ m ' again Schematic diagram.

Specific embodiment

Present invention enforcement is further described below in conjunction with accompanying drawing, following examples are descriptive, is not to limit Property, it is impossible to protection scope of the present invention is limited with this.

A kind of modification method of air leak rate of air preheater to exhaust gas temperature, method and step are as follows：

(1) establishing method condition；Analysis is calculated for convenience, assumes initially that the qualificationss of method are：Inlet temperature is Air preheater inlet temperature, while leaked-in air temperature is calculated with air preheater entrance inlet temperature；

(2) draw the heat balance relational expression between fume side and air side；Thermal balance and flow equilibrium according to Fig. 3 Relation, draws relational expression：

In formula：θ_py-- actual exhaust gas temperature, DEG C；

θ′_py-- exhaust gas temperature after amendment, DEG C；

t₀-- inlet temperature, DEG C；

Δ m-- is actual to leak into air capacity, kg；

Δ m ' -- it is adapted to design air leak rate of air curtain and leaks into air capacity, kg；

m_y-- into the flue gas mass of boiler flue, kg；

-- air is from 0 DEG C of temperature and to t0 DEG C, 0 DEG C and to θ_pyDEG C, 0 DEG C and arrive θ′_pyDEG C average specific heat at constant pressure hold, kJ/ (kgK)；

-- flue gas is from 0 DEG C of temperature and to θ_pyDEG C, 0 DEG C and arrive θ '_pyDEG C average specific heat at constant pressure hold, kJ/(kg·K)；

Actual measurement exhaust gas temperature θ wherein in (A) formula_pyWith exhaust gas temperature θ ' after amendment_pyDifference is not too large, so relevant Temperature θ_pyAnd θ_p′_yThe desirable identical value of specific heat capacity, i.e.,WithValue is WithValue is

(3) determine air leak rate of air curtain formula；Air leak rate of air curtain is to leak into the air quality of air preheater fume side and enter boiler smoke The ratio of the flue gas mass in road, i.e.,：

(4) arrange formula (A)；Substituted according to the value of the air leak rate of air curtain and specific heat capacity that determine, obtained after arranging (A) formula：

In formula：A_L-- actual air leak rate of air curtain, %；

A′_L-- the air leak rate of air curtain under design air leakage coefficient, %；

(5) θ ' that will be obtained_py-- revised exhaust gas temperature value is used for the corrected Calculation of boiler efficiency, to improve boiler effect The accuracy that rate is calculated, so as to the economical operation to detect boiler provides accurate data foundation.

Claims (2)

1. modification method of a kind of air leak rate of air preheater to exhaust gas temperature, it is characterised in that as follows including step：

(1) establishing method condition；Analysis is calculated for convenience, assumes initially that the qualificationss of method are：Inlet temperature is air Pre-heater inlet temperature, while leaked-in air temperature is calculated with air preheater entrance inlet temperature；

(2) draw the heat balance relational expression between fume side and air side；Show that relational expression is：

$\begin{array}{c}\left(\mathrm{\Δ}m-{\mathrm{\Δm}}^{\′}\right)\×C_{p\·k}{|}_{t_0}\×t_0+{\mathrm{\Δm}}^{\′}\×C_{p\·k}{|}_{{\mathrm{\θ}}_{py}^{\′}}\×{\mathrm{\θ}}_{py}^{\′}+m_y\×C_{p\·y}{|}_{{\mathrm{\θ}}_{py}^{\′}}\×{\mathrm{\θ}}_{py}^{\′}\\ =\left(\mathrm{\Δ}m-{\mathrm{\Δm}}^{\′}\right)\×C_{p\·k}{|}_{{\mathrm{\θ}}_{py}}\×{\mathrm{\θ}}_{py}+{\mathrm{\Δm}}^{\′}\×C_{p\·k}{|}_{{\mathrm{\θ}}_{py}}\×{\mathrm{\θ}}_{py}+m_y\×C_{p\·y}{|}_{{\mathrm{\θ}}_{py}}\×{\mathrm{\θ}}_{py}\end{array}---\left(A\right)$

In formula：θ_py-- actual exhaust gas temperature, DEG C；

θ′_py-- exhaust gas temperature after amendment, DEG C；

t₀-- inlet temperature, DEG C；

Δ m-- is actual to leak into air capacity, kg；

Δ m ' -- it is adapted to design air leak rate of air curtain and leaks into air capacity, kg；

m_y-- into the flue gas mass of boiler flue, kg；

-- air is from 0 DEG C of temperature and to t0 DEG C, 0 DEG C and to θ_pyDEG C, 0 DEG C and arrive θ '_py℃ Average specific heat at constant pressure hold, kJ/ (kgK)；

-- flue gas is from 0 DEG C of temperature and to θ_pyDEG C, 0 DEG C and arrive θ '_pyDEG C average specific heat at constant pressure hold, kJ/ (kg·K)；

(3) determine air leak rate of air curtain formula；Air leak rate of air curtain is to leak into the air quality of air preheater fume side and enter boiler flue The ratio of flue gas mass, i.e.,：

$A_L=\frac{\mathrm{\Δ}m}{m_y}---\left(B\right)$

(4) arrange formula (A)；Substituted according to the value of the air leak rate of air curtain and specific heat capacity that determine, obtained after arranging (A) formula：

${\mathrm{\θ}}_{py}^{\′}=\frac{A_L\×C_{p\·k}{|}_{{\mathrm{\θ}}_{py}}\×{\mathrm{\θ}}_{py}+C_{p\·y}{|}_{{\mathrm{\θ}}_{py}}-(A_L-A_L^{\′})\×C_{p\·k}{|}_{t_0}{\×}_{t0}}{A_L^{\′}\×C_{p\·k}{|}_{{\mathrm{\θ}}_{py}}+C_{p\·y}{|}_{{\mathrm{\θ}}_{py}}}---\left(C\right)$

In formula：A_L-- actual air leak rate of air curtain, %；

A′_L-- the air leak rate of air curtain under design air leakage coefficient, %；

(5) θ ' that will be obtained_pyRevised exhaust gas temperature value is used for the corrected Calculation of boiler efficiency.

2. modification method of the air leak rate of air preheater according to claim 1 to exhaust gas temperature, it is characterised in that： θ in (A) formula in the step (2)_pyWith θ '_pySpecific heat capacity take identical value, i.e.,WithValue isWithValue is