CN101825502A - Effluent and drain temperature measurement and calculation method of heater with drain cooler on steam turbine - Google Patents

Abstract

The invention discloses an effluent and drain temperature measurement and calculation method of a heater with a drain cooler on a steam turbine. The method comprises the following steps: a machine set design condition or a performance test condition is selected as a reference condition; the case side pressure, the case side steam extraction enthalpy, the drain temperature, the effluent temperature, the inflow temperature and the machine set power of the heater under the reference condition are selected to calculate the heat transfer characteristic coefficient of the pure condensation section and the drain cooling section of the heater under the reference condition; the case side pressure, the heater inflow temperature and the machine set power under the actual condition are read or calculated in the database of a monitoring information system SIS or a decentralized control system DCS of a heat-engine plant; the heat transfer characteristic coefficient of the pure condensation section of the heater under the actual condition is calculated by the corresponding heat transfer characteristic coefficient of the pure condensation section of the heater under the reference condition; the actual effluent temperature is obtained by iterative computation; the heat transfer characteristic coefficient of the drain cooling section of the heater under the actual condition is calculated according to the heat transfer characteristic coefficient of the drain cooling section of the heater under the reference condition, and the drain temperature is obtained by iterative computation.

Description

The well heater water outlet of steam turbine band drain cooler and drain temperature measuring method

Technical field

The present invention relates to a kind of measuring method of heater parameter of steam turbine band drain cooler, relate in particular to a kind of well heater water outlet and drain temperature measuring method of steam turbine band drain cooler.

Background technology

Along with the continuous lifting of fired power generating unit parameter and capacity, receive publicity day by day to improve the unit operation economy by the performance of improving heat regenerative system.The measurement of bleeder heater water outlet and drain temperature has important effect for the thermally equilibrated calculating of heat regenerative system, unit performance monitoring and optimization, therefore is necessary it is carried out on-line monitoring.So far do not see the report of being with drain cooler well heater water outlet and drain temperature measuring method in the heat regenerative system.

At present, in plant level supervisory information system SIS of thermal power plant (Supervisory Information System) or the scattered control system DCS of system (Distribution Control System), for the bleeder heater that has drain cooler, though be provided with water outlet and drain temperature measuring point, but reason such as abominable and repair and maintenance weakness because of its service condition, ubiquity is measured the situation of poor reliability, in addition, the routine measurement method of well heater water side temperature also has the following disadvantages: at first, in the fired power generating unit thermal measurement system, the normal leaving water temperature that adopts the thermal resistance type sensor to monitor bleeder heater, data acquisition system (DAS) correspondingly need adopt the resistance value of active balancing bridge measurement sensor, measures the cost height; Secondly, water temperature changes thermal inertia greatly, and when power condition changing was big, the water temperature Response Table revealed bigger thermal inertia, thereby influences measuring accuracy; The 3rd, because on-the-spot installation site complexity is not easy to maintenance and maintenance.In case sensor fault or inefficacy often cause the wrong of measurement data or disappearance.

And calculate well heater water outlet and drain temperature according to traditional heat transfer equation, need to calculate the heat transfer coefficient of heat transfer process.Need to understand the numerous structural parameters of well heater in the calculating of heat transfer coefficient, for example: the area of each heat transfer segment of well heater, flow process number, pipe side and shell-side structure, pipeline inner and outer diameter, pipeline material or the like.The disappearance of any well heater data all can cause heat transfer coefficient to calculate, so traditional heat transfer equation is applicable to design and check calculates that and water outlet is calculated and monitored with drain temperature when being not easy to be used for unit operation or test.

Pure condensate knot section heat exchange with hydrophobic cooling section well heater in power plant's heat regenerative system belongs to condensation heat transfer, the heating tube side of drawing gas shell-side feeds water and condenses, be characterized in that the shell-side heat transfer coefficient is very big, gas keeps the saturation temperature of shell pressure correspondence constant in the process of condensation heat.Hydrophobic cooling section conducts heat and belongs to the heat exchange of water water.The present invention is based on above-mentioned heat-transfer mechanism, pure condensate knot section and hydrophobic cooling section heat compensator conducting property coefficient have been defined, found the variable working condition response pattern of pure condensate knot section and hydrophobic cooling section heat compensator conducting property coefficient, proposed based on the band drain cooler well heater water outlet of heat compensator conducting property coefficient and the measuring method of drain temperature, this method does not have need understand structural parameters, measures fast, the reliable measuring data advantages of higher of low, the tested parameter response of cost.

Summary of the invention

Well heater water outlet and the drain temperature measuring method a kind ofly calculating that model is simple, computational accuracy is high, measure the steam turbine band drain cooler of the low and rapid dynamic response speed of cost have been the object of the present invention is to provide.

The present invention realizes by following technical solution:

A kind of well heater water outlet of steam turbine band drain cooler and drain temperature measuring method is characterized in that,

Step 1: the mid-transition point temperature t of calculating well heater pure condensate knot section and hydrophobic cooling section under the benchmark operating mode _{Wn (j+1)} ^o:

Choose unit rated load design conditions or performance certification test operating mode as the benchmark operating mode, symbol add marking-up mother " o " parametric representation its be the parameter under the benchmark operating mode, choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure p _Nj ^o, the shell-side enthalpy h that draws gas _Nj ^o, drain temperature t _Dj ^o, leaving water temperature t _Wj ^o, inflow temperature t _{W (j+1)} ^oWith power of the assembling unit P _e ^o, and according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation shell pressure p _Nj ^oFollowing corresponding saturation temperature t _Sj ^oAnd saturation water enthalpy h _Swj ^o,

Tie the section thermal balance equation by the well heater pure condensate:

And hydrophobic cooling section thermal balance equation:

In the formula: j is the well heater numbering, is numbered respectively from high to low 1～n number according to the well heater extraction pressure, and n is the positive integer greater than 1;

D _j ^oBe the j level well heater amount of drawing gas, unit is kg/h;

h _Nj ^oBe j level well heater shell-side extraction pressure enthalpy, unit is kJ/kg;

h _Swj ^oBe the saturation water enthalpy of j level heater case wall pressure correspondence, unit is kJ/kg;

D _Wj ^oBe j level well heater feedwater flow, unit is kg/h;

C _pSpecific heat at constant pressure for feedwater is taken as definite value: 4.1868kJ/ (kg ℃);

t _Wj ^oBe the leaving water temperature of j level well heater, unit is ℃;

t _{W (j+1)} ^oBe the inflow temperature of j level well heater, unit is ℃;

Hydrophobic enthalpy

Unit is kJ/kg;

Obtain pure condensate knot section and the middle transition temperature of hydrophobic cooling section and the relational expression of well heater import and export feed temperature after the arrangement:

$t_{\mathrm{wn}(j+1)}^o=\frac{t_{\mathrm{wj}}^o+t_{w(j+1)}^o\·(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)}{(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)+1},$

Step 2: the heat compensator conducting property coefficient of well heater pure condensate knot section and hydrophobic cooling section under the calculating benchmark operating mode

(1) by the knot of the pure condensate under benchmark operating mode section heat transfer equation:

${\left(\mathrm{KF}\right)}_N^o\·\mathrm{\Δ}{t}_m={\left(D_w{C}_p\right)}_N^o\·(t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o),$

Wherein: subscript " N " expression pure condensate knot section, (KF) _N ^oBe the product of pure condensate knot section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _N ^oBe the knot of the pure condensate under benchmark operating mode section feedwater flow D _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ/ (kg a ℃);

Pure condensate knot section heat transfer temperature difference under the benchmark operating mode:

$\mathrm{\Δ}{t}_m=\frac{(t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o)-(t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o)}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}=\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}$

Obtain the heat compensator conducting property coefficient of the pure condensate knot section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o=\ln (\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}+1),$

(2) by the hydrophobic cooling section heat transfer equation under the benchmark operating mode:

${\left(\mathrm{KF}\right)}_{\mathrm{DC}}^o\·\mathrm{\Δ}{t}_m={\left(D_w{C}_p\right)}_{\mathrm{DC}}^o\·(t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o),$

Wherein: subscript " DC " is represented hydrophobic cooling section, (KF) _SC ^oBe the product of hydrophobic cooling section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _DC ^oFeedwater flow D for the hydrophobic cooling section under the benchmark operating mode _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ/ (kg a ℃); Hydrophobic cooling section heat transfer temperature difference under the benchmark operating mode Obtain the heat compensator conducting property coefficient of the hydrophobic cooling section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o=\frac{\ln \left(\frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{dj}}^o-t_{w(j+1)}^o}\right)}{\frac{t_{\mathrm{sj}}^o-t_{\mathrm{dj}}^o}{t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o}-1}$

Step 3: the drain temperature t that calculates well heater under the actual condition _DjWith leaving water temperature t _Wj:

Step 3.1: in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the shell pressure p under the actual condition _Nj, j level well heater inflow temperature t _{W (j+1)}With power of the assembling unit P _e, as if the shell pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _Nj, then by calculating the shell pressure p under the actual condition _Nj, go out shell pressure p under the actual condition according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation again _NjSaturation temperature t under the corresponding actual condition _SjAnd saturation water enthalpy h _Swj, as if the j level well heater inflow temperature t that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{W (j+1)}, then by calculating the j level well heater inflow temperature t under the actual condition _{W (j+1)},

Shell pressure p under the described calculating actual condition _NjMethod be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the extraction pressure p under the actual condition _j, calculate the shell pressure p under the actual condition _Nj=p _j(1-δ p _j), δ p _jBe pipeline crushing rate, δ p _j=3%～5%;

J level well heater inflow temperature t under the described calculating actual condition _{W (j+1)}Method be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}, as if the j+1 level heater case wall pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{N (j+1)}, then in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level well heater extraction pressure p under the actual condition _J+1, calculate the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}=p _J+1(1-δ p _J+1), δ p _J+1Be the pipeline crushing rate of the j+1 level well heater under the actual condition, δ p _J+1=3%～5%; Then according to the j+1 level heater case wall pressure p under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation actual condition _{N (j+1)}Corresponding saturation temperature t _{S (j+1)}, and deduct the end difference θ of j+1 level well heater under design conditions with saturation temperature _J+1, and be j level well heater inflow temperature t under the actual condition with this difference _{W (j+1)}, i.e. t _{W (j+1)}=t _{S (j+1)}-θ _J+1,

Because the enthalpy that draws gas of variable working condition post-heater remains unchanged substantially, so the shell-side enthalpy h that draws gas under the actual condition _NjCan be similar to the enthalpy of getting under the benchmark operating mode that draws gas,

The calculating of water outlet and drain temperature under step 3.2 actual condition:

The iterative computation step:

Drain temperature t is set _DjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 5 as iteration initial value (t _Dj) _K=0, wherein subscript k is an iterations;

Set out coolant-temperature gage t _WjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 15 as iteration initial value (t _Wj) _L=0, wherein subscript l is an iterations;

By leaving water temperature t _WjWith drain temperature t _DjDefault calculate pure condensate knot section and hydrophobic cooling section middle transition temperature:

${\left(t_{\mathrm{wn}(j+1)}\right)}_{l+1}=\frac{{\left(t_{\mathrm{wj}}\right)}_l+t_{w(j+1)}\·(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.1868)}{(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.186)+1}---\left(1\right),$

Middle transition temperature (the t that calculates _{Wn (j+1)}) _L+1, according to a pure condensate knot section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, by the power of the assembling unit P of benchmark operating mode respective heater pure condensate knot section heat compensator conducting property coefficient and actual condition _eCalculate the heat compensator conducting property coefficient of the well heater pure condensate knot section under the actual condition, finally according to the actual leaving water temperature of this heat compensator conducting property coefficient calculations:

${\left(t_{\mathrm{wj}}\right)}_l=\frac{t_{\mathrm{sj}}\·[\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})-1]+{\left(t_{\mathrm{wn}(j+1)}\right)}_l}{\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})}$

If current leaving water temperature (t _Wj) _lDo not meet the first iteration convergence condition, then leaving water temperature newly is worth substitution formula (1) and continues iteration, the described first iteration convergence condition is:

Δ t _{Wn (j+1)}=| (t _{Wn (j+1)}) _L+1-(t _{Wn (j+1)}) _l|≤0.01 and Δ t _Wj=| (t _Wj) _L+1-(t _Wj) _l|≤0.01,

Then according to hydrophobic cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, calculate the heat compensator conducting property coefficient of the heater condensate cooling section under the actual condition by the power of the assembling unit Pe of benchmark operating mode respective heater hydrophobic cooling section heat compensator conducting property coefficient and actual condition, finally according to this heat compensator conducting property coefficient and pure condensate knot section middle transition temperature (t with hydrophobic cooling section _{Wn (j+1)}) _L+1Calculate drain temperature:

${\left(t_{\mathrm{dj}}\right)}_k=\frac{t_{\mathrm{sj}}-t_{\mathrm{wn}(j+1)}}{\exp [{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o\·{\left(\frac{P_e}{P_e^o}\right)}^m\·\left(\frac{t_{\mathrm{sj}}-{\left(t_{\mathrm{dj}}\right)}_{k-1}}{t_{\mathrm{wn}(j+1)}-t_{w(j+1)}}\right)-1]}+t_{w(j+1)}$

Wherein: m is the power of the assembling unit P under the actual condition _eWith the power of the assembling unit P under the benchmark operating mode _e ^oThe index of ratio is for high-pressure heater m=0.6, for low-pressure heater m=0.3

If current drain temperature (t _Dj) _kDo not meet the secondary iteration condition of convergence, then drain temperature newly is worth substitution formula (1) and continues iterative computation, the described secondary iteration condition of convergence is: Δ t _Dj=| (t _Dj) _k-(t _Dj) _K-1|≤0.01,

After the iterative computation convergence finishes, current leaving water temperature (t _Wj) _lAnd drain temperature (t _Dj) _kLeaving water temperature t as well heater _WjWith drain temperature t _DjEnd value.

The invention has the advantages that:

The present invention is based on heat-transfer mechanism and can survey parameter with operation, defined the heat compensator conducting property coefficient of pure condensate knot section and hydrophobic cooling section, utilize the rule of the heat compensator conducting property coefficient random groups variable power of newfound pure condensate knot section and hydrophobic cooling section, proposes a kind of indirect, simple and direct, method that high precision is calculated based on well heater water outlet of being with drain cooler in the heat compensator conducting property coefficient measuring and calculating fired power generating unit heat regenerative system and drain temperature.This method only needs design (perhaps test) benchmark floor data, and need not understand structural parameters, and model is simple and direct; Only need can survey parameter according to operation, measuring and calculating water outlet and drain temperature can reduce the measurement cost; Because model uses dynamic response fast (as pressure) and high precision water and steam character model, can significantly improve tested parameter response speed and measure reliability.

1, the measuring and calculating model is simple, the computational accuracy height

The measuring and calculating model that the present invention set up, only need parameter and the extraction pressure and the unit load etc. of a spot of benchmark operating mode (design conditions or thermal test operating mode) can survey parameter on a small quantity, need not the structural parameters of well heater and flow parameter (regenerative steam flow and feedwater or coagulate discharge), model is simple, it is simple and direct to calculate.

Than traditional well heater variable working condition model, its computational accuracy height shows two aspects, the one, and the heat compensator conducting property coefficient can reflect the influence of load variations, improves response accuracy; The 2nd, what the key of water outlet, drain temperature computation model precision was the heat compensator conducting property coefficient calculates the precision of model with water vapor, and the heat compensator conducting property coefficient to calculate the precision of model all higher with water vapor, so guaranteed computation model precision of the present invention.

2, make full use of the relevant measurement result that can survey parameter, it is low to measure cost

The present invention utilizes the measurement result of pressure of extracted steam from turbine (the important measurement parameter of turbine system), realize the measuring and calculating of well heater water outlet and drain temperature by model, only need pressure-measuring-point relevant in DCS or the SIS system, and need not special temperature point, measure cost by the shared reduction of metrical information.

3, use the measuring and calculating model, can significantly improve the dynamic responding speed of tested parameter

Utilize rule and the high-precision water and steam character model of the heat compensator conducting property coefficient of bleeder heater pure condensate knot section and hydrophobic cooling section with variable power, the dynamic response of the measurement result of well heater water outlet and drain temperature is equivalent to the dynamic responding speed of extraction pressure and unit load, thereby has improved the dynamic responding speed of well heater water outlet and drain temperature results of measuring.

4, improved the measurement reliability of tested parameter

Extraction pressure that uses in the model and unit load are the important monitoring parameters of steam turbine, often take the redundant arrangement of measuring point to improve its reliability with measures such as making things convenient for repair and maintenance, adopt the measuring and calculating model with the measurement certainty equivalence of well heater water outlet and drain temperature in extraction pressure and unit load measuring reliability, thereby improved well heater water outlet and drain temperature measuring reliability.

Description of drawings

Fig. 1 is the principled thermal system figure of the surface heater of band drain cooler

Fig. 2 is well heater heat transfer process T-F (temperature-structure) figure

Fig. 3 is a calculation flow chart of the present invention

Embodiment

A kind of well heater water outlet of steam turbine band drain cooler and drain temperature measuring method is characterized in that,

Step 1: the mid-transition point temperature t of calculating well heater pure condensate knot section and hydrophobic cooling section under the benchmark operating mode _{Wn (j+1)} ^o:

Choose unit rated load design conditions or performance certification test operating mode as the benchmark operating mode, symbol add marking-up mother " o " parametric representation its be the parameter under the benchmark operating mode, choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure p _Nj ^o, the shell-side enthalpy h that draws gas _Nj ^o, drain temperature t _Dj ^o, leaving water temperature t _Wj ^o, inflow temperature t _{W (j+1)} ^oWith power of the assembling unit P _e ^o, and according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation shell pressure p _Nj ^oFollowing corresponding saturation temperature t _Sj ^oAnd saturation water enthalpy h _Swj ^o,

Tie the section thermal balance equation by the well heater pure condensate:

And hydrophobic cooling section thermal balance equation:

In the formula: j is the well heater numbering, is numbered respectively from high to low 1～n number according to the well heater extraction pressure, and n is the positive integer greater than 1;

D _j ^oBe the j level well heater amount of drawing gas, unit is kg/h;

h _Nj ^oBe j level well heater shell-side extraction pressure enthalpy, unit is kJ/kg;

h _Swj ^oBe the saturation water enthalpy of j level heater case wall pressure correspondence, unit is kJ/kg;

D _Wj ^oBe j level well heater feedwater flow, unit is kg/h;

C _pSpecific heat at constant pressure for feedwater is taken as definite value: 4.1868kJ/ (kg ℃);

t _Wj ^oBe the leaving water temperature of j level well heater, unit is ℃;

t _{W (j+1)} ^oBe the inflow temperature of j level well heater, unit is ℃;

Hydrophobic enthalpy

Unit is kJ/kg;

Obtain pure condensate knot section and the middle transition temperature of hydrophobic cooling section and the relational expression of well heater import and export feed temperature after the arrangement:

$t_{\mathrm{wn}(j+1)}^o=\frac{t_{\mathrm{wj}}^o+t_{w(j+1)}^o\·(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)}{(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)+1},$

Step 2: the heat compensator conducting property coefficient of well heater pure condensate knot section and hydrophobic cooling section under the calculating benchmark operating mode

(1) by the knot of the pure condensate under benchmark operating mode section heat transfer equation:

${\left(\mathrm{KF}\right)}_N^o\·\mathrm{\Δ}{t}_m={\left(D_w{C}_p\right)}_N^o\·(t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o),$

Wherein: subscript " N " expression pure condensate knot section, (KF) _N ^oBe the product of pure condensate knot section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _N ^oBe the knot of the pure condensate under benchmark operating mode section feedwater flow D _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ/ (kg a ℃);

Pure condensate knot section heat transfer temperature difference under the benchmark operating mode:

$\mathrm{\Δ}{t}_m=\frac{(t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o)-(t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o)}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}=\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}$

Obtain the heat compensator conducting property coefficient of the pure condensate knot section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o=\ln (\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}+1),$

(2) by the hydrophobic cooling section heat transfer equation under the benchmark operating mode:

${\left(\mathrm{KF}\right)}_{\mathrm{DC}}^o\·\mathrm{\Δ}{t}_m={\left(D_w{C}_p\right)}_{\mathrm{DC}}^o\·(t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o),$

Wherein: subscript " DC " is represented hydrophobic cooling section, (KF) _SC ^oBe the product of hydrophobic cooling section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _DC ^oFeedwater flow D for the hydrophobic cooling section under the benchmark operating mode _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ (kg a ℃);

Hydrophobic cooling section heat transfer temperature difference under the benchmark operating mode

Obtain the heat compensator conducting property coefficient of the hydrophobic cooling section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o=\frac{\ln \left(\frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{dj}}^o-t_{w(j+1)}^o}\right)}{\frac{t_{\mathrm{sj}}^o-t_{\mathrm{dj}}^o}{t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o}-1}$

Step 3: the drain temperature t that calculates well heater under the actual condition _DjWith leaving water temperature t _Wj:

Step 3.1: in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the shell pressure p under the actual condition _Nj, j level well heater inflow temperature t _{W (j+1)}With power of the assembling unit P _e, as if the shell pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _Nj, then by calculating the shell pressure p under the actual condition _Nj, go out shell pressure p under the actual condition according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation again _NjSaturation temperature t under the corresponding actual condition _SjAnd saturation water enthalpy h _Swj, as if the j level well heater inflow temperature t that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{W (j+1)}, then by calculating the j level well heater inflow temperature t under the actual condition _{W (j+1)},

Shell pressure p under the described calculating actual condition _NjMethod be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the extraction pressure p under the actual condition _j, calculate the shell pressure p under the actual condition _Nj=p _j(1-δ p _j), δ p _jBe pipeline crushing rate, δ p _j=3%～5%;

J level well heater inflow temperature t under the described calculating actual condition _{W (j+1)}Method be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}, as if the j+1 level heater case wall pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{N (j+1)}, then in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level well heater extraction pressure p under the actual condition _J+1, calculate the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}=p _J+1(1-δ p _J+1), δ p _J+1Be the pipeline crushing rate of the j+1 level well heater under the actual condition, δ p _J+1=3%～5%; Then according to the j+1 level heater case wall pressure p under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation actual condition _{N (j+1)}Corresponding saturation temperature t _{S (j+1)}, and deduct the end difference θ of j+1 level well heater under design conditions with saturation temperature _J+1, and be j level well heater inflow temperature t under the actual condition with this difference _{W (j+1)}, i.e. t _{W (j+1)}=t _{S (j+1)}-θ _J+1,

Because the enthalpy that draws gas of variable working condition post-heater remains unchanged substantially, so the shell-side enthalpy h that draws gas under the actual condition _NjCan be similar to the enthalpy of getting under the benchmark operating mode that draws gas,

The calculating of water outlet and drain temperature under step 3.2 actual condition:

The iterative computation step:

Drain temperature t is set _DjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 5 as iteration initial value (t _Dj) _K=0, wherein subscript k is an iterations;

Set out coolant-temperature gage t _WjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 15 as iteration initial value (t _Wj) _L=0, wherein subscript l is an iterations;

By leaving water temperature t _WjWith drain temperature t _DjDefault calculate pure condensate knot section and hydrophobic cooling section middle transition temperature:

${\left(t_{\mathrm{wn}(j+1)}\right)}_{l+1}=\frac{{\left(t_{\mathrm{wj}}\right)}_l+t_{w(j+1)}\·(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.1868)}{(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.186)+1}---\left(1\right),$

Middle transition temperature (the t that calculates _{Wn (j+1)}) _L+1, according to a pure condensate knot section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, by the power of the assembling unit P of benchmark operating mode respective heater pure condensate knot section heat compensator conducting property coefficient and actual condition _eCalculate the heat compensator conducting property coefficient of the well heater pure condensate knot section under the actual condition, finally according to the actual leaving water temperature of this heat compensator conducting property coefficient calculations:

${\left(t_{\mathrm{wj}}\right)}_l=\frac{t_{\mathrm{sj}}\·[\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})-1]+{\left(t_{\mathrm{wn}(j+1)}\right)}_l}{\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})}$

If current leaving water temperature (t _Wj) _lDo not meet the first iteration convergence condition, then leaving water temperature newly is worth substitution formula (1) and continues iteration, the described first iteration convergence condition is:

Δ t _{Wn (j+1)}=| (t _{Wn (j+1)}) _L+1-(t _{Wn (j+1)}) _l|≤0.01 and Δ t _Wj=| (t _Wj) _L+1-(t _Wj) _l|≤0.01,

Then according to hydrophobic cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, by the power of the assembling unit P of benchmark operating mode respective heater hydrophobic cooling section heat compensator conducting property coefficient and actual condition _eCalculate the heat compensator conducting property coefficient of the heater condensate cooling section under the actual condition, finally according to this heat compensator conducting property coefficient and pure condensate knot section middle transition temperature (t with hydrophobic cooling section _{Wn (j+1)}) _L+1Calculate drain temperature:

${\left(t_{\mathrm{dj}}\right)}_k=\frac{t_{\mathrm{sj}}-t_{\mathrm{wn}(j+1)}}{\exp [{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o\·{\left(\frac{P_e}{P_e^o}\right)}^m\·\left(\frac{t_{\mathrm{sj}}-{\left(t_{\mathrm{dj}}\right)}_{k-1}}{t_{\mathrm{wn}(j+1)}-t_{w(j+1)}}\right)-1]}+t_{w(j+1)}$

Wherein: m is the power of the assembling unit P under the actual condition _eWith the power of the assembling unit P under the benchmark operating mode _e ^oThe index of ratio is for high-pressure heater m=0.6, for low-pressure heater m=0.3

If current drain temperature (t _Dj) _kDo not meet the secondary iteration condition of convergence, then drain temperature newly is worth substitution formula (1) and continues iterative computation, the described secondary iteration condition of convergence is: Δ t _Dj=| (t _Dj) _k-(t _Dj) _K-1|≤0.01,

After the iterative computation convergence finishes, current leaving water temperature (t _Wj) _lAnd drain temperature (t _Dj) _kLeaving water temperature t as well heater _WjWith drain temperature t _DjEnd value.

With the 600MW unit is example, realizes the water outlet of band drain cooler well heater in the Steam Turbine Regenerative System and the measuring and calculating of drain temperature.The #5 well heater of this unit is the low-pressure heater of band drain cooler.

The detailed calculated step is as follows:

(1), calculate well heater pure condensate knot section and hydrophobic cooling section under the benchmark operating mode the mid-transition point temperature t _Wn6 ^o:

The design conditions of choosing the unit rated load are the benchmark operating mode, and the shell pressure p of #5 well heater is arranged according to design parameter _N5 ^oBe 0.4017MPa, the shell-side enthalpy h that draws gas _N5 ^oBe 2979.70kJ/kg, drain temperature t _D5 ^o107.1 ℃, leaving water temperature t _W5 ^oBe 141 ℃, inflow temperature t _W6 ^oIt is 101.5 ℃.Saturation temperature t according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation shell pressure correspondence _S5 ^oBe 143.8 ℃, saturation water enthalpy h _Sw5 ^oBe 605.4kJ/kg.Hydrophobic enthalpy

(2), the heat compensator conducting property coefficient of well heater pure condensate knot section and hydrophobic cooling section under the calculating benchmark operating mode

Calculate well heater pure condensate knot section heat compensator conducting property coefficient:

Calculate hydrophobic cooling section heat compensator conducting property coefficient:

(3), calculate the drain temperature t of well heater under the actual condition _D5With leaving water temperature t _W5:

When level pressure 75% load, from the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, get the shell pressure p under the actual condition _N5Be 0.3163MPa, the shell-side enthalpy h that draws gas _N5Be taken as the analog value 2979.70kJ/kg under the benchmark operating mode, well heater inflow temperature t _W6It is 94.2 ℃.Go out shell pressure p according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation _N5Corresponding saturation temperature t _S5Be 135.3 ℃, saturation water enthalpy h _Sw5Be 569.2kJ/kg.

Well heater inflow temperature t is set _W6+ 5=99.2 ℃ is drain temperature t _D5Iterative initial value,

Well heater inflow temperature t is set _W6+ 15=109.2 ℃ is leaving water temperature t _W5Iterative initial value.

By the calculation process iterative computation of following formula according to Fig. 3,

${\left(t_{\mathrm{wn}6}\right)}_{l+1}=\frac{{\left(t_{w5}\right)}_l+t_{w6}\·(h_5-h_{\mathrm{sw}5})/(h_{\mathrm{sw}5}-{\left(t_{d5}\right)}_l\·4.1868)}{(h_5-h_{\mathrm{sw}})/(h_{\mathrm{sw}5}-{\left(t_{d5}\right)}_l\·4.186)+1}$

${\left(t_{w5}\right)}_l=\frac{t_{s5}\·[\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{N5}^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})-1]+{\left(t_{\mathrm{wn}6}\right)}_l}{\exp [{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{N5}^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2}]}$

${\left(t_{d5}\right)}_k=\frac{t_{s5}-t_{\mathrm{wn}6}}{\exp [{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}5}^o\·{\left(\frac{P_e}{P_e^o}\right)}^{0.3}\·\left(\frac{t_{s5}-{\left(t_{d5}\right)}_{k-1}}{t_{\mathrm{wn}6}-t_{w6}}\right)-1]}+t_{w6}$

Through 3 systemic circulation iteration (the partial circulating iterations among Fig. 3 in each systemic circulation iteration is respectively 3,1,1), finally calculate the leaving water temperature t of well heater _W5Be 133.096 ℃ and drain temperature t _D5Be 100.898 ℃, be respectively with measured value 132.6,99.8 relative errors :-0.374% and-1.100%.

Claims (1)

1. the well heater water outlet of a steam turbine band drain cooler and drain temperature measuring method is characterized in that,

Step 1: the mid-transition point temperature t of calculating well heater pure condensate knot section and hydrophobic cooling section under the benchmark operating mode _{Wn (j+1)} ^o:

Choose unit rated load design conditions or performance certification test operating mode as the benchmark operating mode, symbol add marking-up mother " o " parametric representation its be the parameter under the benchmark operating mode, choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure p _Nj ^o, the shell-side enthalpy h that draws gas _Nj ^o, drain temperature t _Dj ^o, leaving water temperature t _Wj ^o, inflow temperature t _{W (j+1)} ^oWith power of the assembling unit P _e ^o, and according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation shell pressure p _Nj ^oFollowing corresponding saturation temperature t _Sj ^oAnd saturation water enthalpy h _Swj ^o,

Tie the section thermal balance equation by the well heater pure condensate:

And hydrophobic cooling section thermal balance equation:

In the formula: j is the well heater numbering, is numbered respectively from high to low 1～n number according to the well heater extraction pressure, and n is the positive integer greater than 1;

D _j ^oBe the j level well heater amount of drawing gas, unit is kg/h;

h _Nj ^oBe j level well heater shell-side extraction pressure enthalpy, unit is kJ/kg;

h _Swj ^oBe the saturation water enthalpy of j level heater case wall pressure correspondence, unit is kJ/kg;

D _Wj ^oBe j level well heater feedwater flow, unit is kg/h;

C _pSpecific heat at constant pressure for feedwater is taken as definite value: 4.1868kJ/ (kg ℃);

t _Wj ^oBe the leaving water temperature of j level well heater, unit is ℃;

t _{W (j+1)} ^oBe the inflow temperature of j level well heater, unit is ℃;

Hydrophobic enthalpy

Unit is kJ/kg;

Obtain pure condensate knot section and the middle transition temperature of hydrophobic cooling section and the relational expression of well heater import and export feed temperature after the arrangement:

$t_{\mathrm{wn}(j+1)}^o=\frac{t_{\mathrm{wj}}^o+t_{w(j+1)}^o\·(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)}{(h_{\mathrm{nj}}^o-h_{\mathrm{swj}}^o)/(h_{\mathrm{swj}}^o-h_{\mathrm{dj}}^o)+1},$

Step 2: the heat compensator conducting property coefficient of well heater pure condensate knot section and hydrophobic cooling section under the calculating benchmark operating mode

(1) by the knot of the pure condensate under benchmark operating mode section heat transfer equation:

${\left(\mathrm{KF}\right)}_N^o\·{\mathrm{\Δt}}_m={\left(D_w{C}_p\right)}_N^o\·(t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o),$

Wherein: subscript " N " expression pure condensate knot section, (KF) _N ^oBe the product of pure condensate knot section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _N ^oBe the knot of the pure condensate under benchmark operating mode section feedwater flow D _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ (kg a ℃);

Pure condensate knot section heat transfer temperature difference under the benchmark operating mode:

${\mathrm{\Δt}}_m=\frac{(t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o)-(t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o)}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}=\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{\ln \frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}}$

Obtain the heat compensator conducting property coefficient of the pure condensate knot section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o=\ln (\frac{t_{\mathrm{wj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{sj}}^o-t_{\mathrm{wj}}^o}+1),$

(2) by the hydrophobic cooling section heat transfer equation under the benchmark operating mode:

${\left(\mathrm{KF}\right)}_{\mathrm{DC}}^o\·{\mathrm{\Δt}}_m={\left(D_w{C}_p\right)}_{\mathrm{DC}}^o\·(t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o),$

Wherein: subscript " DC " is represented hydrophobic cooling section, (KF) _SC ^oBe the product of hydrophobic cooling section Coefficient K and heat transfer area F under the benchmark operating mode, unit is kJ/ (m ²℃ h) m ²

(D _wC _p) _DC ^oFeedwater flow D for the hydrophobic cooling section under the benchmark operating mode _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ/ (kg a ℃);

Hydrophobic cooling section heat transfer temperature difference under the benchmark operating mode

Obtain the heat compensator conducting property coefficient of the hydrophobic cooling section under the benchmark operating mode:

${\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o=\frac{\ln \left(\frac{t_{\mathrm{sj}}^o-t_{\mathrm{wn}(j+1)}^o}{t_{\mathrm{dj}}^o-t_{w(j+1)}^o}\right)}{\frac{t_{\mathrm{sj}}^o-t_{\mathrm{dj}}^o}{t_{\mathrm{wn}(j+1)}^o-t_{w(j+1)}^o}-1}$

Step 3: the drain temperature t that calculates well heater under the actual condition _DjWith leaving water temperature t _Wj:

Step 3.1: in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the shell pressure p under the actual condition _Nj, j level well heater inflow temperature t _{W (j+1)}With power of the assembling unit P _e, as if the shell pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _Nj, then by calculating the shell pressure p under the actual condition _Nj, go out shell pressure p under the actual condition according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation again _NjSaturation temperature t under the corresponding actual condition _SjAnd saturation water enthalpy h _Swj, as if the j level well heater inflow temperature t that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{W (j+1)}, then by calculating the j level well heater inflow temperature t under the actual condition _{W (j+1)},

Shell pressure p under the described calculating actual condition _NjMethod be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the extraction pressure p under the actual condition _j, calculate the shell pressure p under the actual condition _Nj=p _j(1-δ p _j), δ p _jBe pipeline crushing rate, δ p _j=3%～5%;

J level well heater inflow temperature t under the described calculating actual condition _{W (j+1)}Method be:

In the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}, as if the j+1 level heater case wall pressure p that in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, does not read under the actual condition _{N (j+1)}, then in the database of plant level supervisory information system SIS of thermal power plant or scattered control system DCS, read the j+1 level well heater extraction pressure p under the actual condition _J+1, calculate the j+1 level heater case wall pressure p under the actual condition _{N (j+1)}=p _J+1(1-δ p _J+1), δ p _J+1Be the pipeline crushing rate of the j+1 level well heater under the actual condition, δ p _J+1=3%～5%; Then according to the j+1 level heater case wall pressure p under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation actual condition _{N (j+1)}Corresponding saturation temperature t _{S (j+1)}, and deduct the end difference θ of j+1 level well heater under design conditions with saturation temperature _J+1, and be j level well heater inflow temperature t under the actual condition with this difference _{W (j+1)}, i.e. t _{W (j+1)}=t _{S (j+1)}-θ _J+1,

Because the enthalpy that draws gas of variable working condition post-heater remains unchanged substantially, so the shell-side enthalpy h that draws gas under the actual condition _NjCan be similar to the enthalpy of getting under the benchmark operating mode that draws gas,

The calculating of water outlet and drain temperature under step 3.2 actual condition:

The iterative computation step:

Drain temperature t is set _DjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 5 as iteration initial value (t _Dj) _K=0, wherein subscript k is an iterations;

Set out coolant-temperature gage t _WjIterative initial value, get well heater inflow temperature t _{W (j+1)}+ 15 as iteration initial value (t _Wj) _L=0, wherein subscript l is an iterations;

By leaving water temperature t _WjWith drain temperature t _DjDefault calculate pure condensate knot section and hydrophobic cooling section middle transition temperature:

${\left(t_{\mathrm{wn}(j+1)}\right)}_{l+1}=\frac{{\left(t_{\mathrm{wj}}\right)}_l+t_{w(j+1)}\·(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.1868)}{(h_{\mathrm{nj}}-h_{\mathrm{swj}})/(h_{\mathrm{swj}}-{\left(t_{\mathrm{dj}}\right)}_l\·4.186)+1}---\left(1\right),$

Middle transition temperature (the t that calculates _{Wn (j+1)}) _L+1, according to a pure condensate knot section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, by the power of the assembling unit P of benchmark operating mode respective heater pure condensate knot section heat compensator conducting property coefficient and actual condition _eCalculate the heat compensator conducting property coefficient of the well heater pure condensate knot section under the actual condition, finally according to the actual leaving water temperature of this heat compensator conducting property coefficient calculations:

${\left(t_{\mathrm{wj}}\right)}_l=\frac{t_{\mathrm{sj}}\·[\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})-1]+{\left(t_{\mathrm{wn}(j+1)}\right)}_l}{\exp ({\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_N^o\·{\left(\frac{P_e}{P_e^o}\right)}^{-0.2})}$

If current leaving water temperature (t _Wj) _lDo not meet the first iteration convergence condition, then leaving water temperature newly is worth substitution formula (1) and continues iteration, the described first iteration convergence condition is:

Δ t _{Wn (j+1)}=| (t _{Wn (j+1)}) _L+1-(t _{Wn (j+1)}) _l|≤0.01 and Δ t _Wj=| (t _Wj) _L+1-(t _Wj) _l)≤0.01,

Then according to hydrophobic cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, by the power of the assembling unit P of benchmark operating mode respective heater hydrophobic cooling section heat compensator conducting property coefficient and actual condition _eCalculate the heat compensator conducting property coefficient of the heater condensate cooling section under the actual condition, finally according to this heat compensator conducting property coefficient and pure condensate knot section middle transition temperature (t with hydrophobic cooling section _{Wn (j+1)}) _L+1Calculate drain temperature:

${\left(t_{\mathrm{dj}}\right)}_k=\frac{t_{\mathrm{sj}}-t_{\mathrm{wn}(j+1)}}{\exp [{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{DC}}^o\·{\left(\frac{P_e}{P_e^o}\right)}^m\·(\frac{t_{\mathrm{sj}}-{\left(t_{\mathrm{dj}}\right)}_{k-1}}{t_{\mathrm{wn}(j+1)}-t_{w(j+1)}}-1)]}+t_{w(j+1)}$

Wherein: m is the power of the assembling unit P under the actual condition _eWith the power of the assembling unit P under the benchmark operating mode _e ^oThe index of ratio is for high-pressure heater m=0.6, for low-pressure heater m=0.3

If current drain temperature (t _Dj) _kDo not meet the secondary iteration condition of convergence, then drain temperature newly is worth substitution formula (1) and continues iterative computation, the described secondary iteration condition of convergence is: Δ t _Dj=| (t _Dj) _k-(t _Dj) _K-1|≤0.01,

After the iterative computation convergence finishes, current leaving water temperature (t _Wj) _lAnd drain temperature (t _Dj) _kLeaving water temperature t as well heater _WjWith drain temperature t _DjEnd value.

Images