CN101832545B - Method for measuring temperatures of out-flowing water and discharged water of heater of turbine steam cooler - Google Patents

Abstract

The invention discloses a method for measuring the temperatures of the out-flowing water and the discharged water of a heater of a turbine steam cooler, which comprises the following steps: selecting a design condition or performance test condition of an assembling unit as reference conditions, and selecting the thermodynamic parameters of the j(th) heater under the reference conditions, wherein the thermodynamic parameters comprise a shell pressure, an extraction temperature, a shell extraction enthalpy, an out-flowing water temperature, a water inlet temperature and a power of the assembling unit; calculating the heat-transfer characteristic coefficient of a stream cooling section of the heater under the reference conditions; reading or calculating the actual shell pressure, extraction temperature, water inlet temperature of the j(th) heater and the actual power of the assembling unit from a supervisor information system (SIS) or decentralized control system (DCS) of a heat-engine plant; calculating and obtaining the heat-transfer characteristic coefficient of the heater according to the heat-transfer characteristic coefficient of the stream cooling section of the heater and the actual power of the assembling unit; and finally obtaining the out-flowing water temperature under the actual conditions by carrying out iterative computations, wherein the out-flowing water temperature is equal to the saturation temperature under the shell pressure.

Description

The well heater water outlet of steam turbine carrying vapour refrigeratory and drain temperature measuring method

Technical field

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

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 well heater water outlet of carrying vapour refrigeratory in the heat regenerative system and the report of drain temperature measuring method.

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 steam condenser, 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.

The heat exchange of well heater pure condensate knot section belongs to condensation heat transfer in power plant's heat regenerative system, and draw gas heating tube side feedwater and condensing of shell-side is characterized in that the shell-side heat transfer coefficient is very big, and gas keeps the saturation temperature of shell pressure correspondence constant in the process of condensation heat.And the heat exchange of steam condenser section belongs to steam-water heat exchanging, but the shell-side feedwater flow is much bigger with pipe side extraction flow relatively.The present invention is based on above-mentioned heat-transfer mechanism, defined the heat compensator conducting property coefficient of steam cooling section and pure condensate knot section, found the variable working condition response pattern of steam cooling section heat compensator conducting property coefficient, the well heater water outlet of carrying vapour refrigeratory and the measuring method of drain temperature have been proposed, 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 carrying vapour refrigeratory 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 carrying vapour refrigeratory and drain temperature measuring method is characterized in that,

Step 1: the mid-transition point temperature t of well heater steam cooling section and pure condensate knot section under the calculating benchmark operating mode _Wsj ^o:

Choose unit rated power 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, and choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure p _Nj ^o, extraction temperature t _j ^o, the shell-side enthalpy h that draws gas _Nj ^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 shell pressure p under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode _Nj ^oCorresponding saturation temperature t _Sj ^o, saturated air enthalpy h _Ssj ^oAnd saturation water enthalpy h _Swj ^o, by the shell pressure p under the benchmark operating mode _Nj ^o, extraction temperature t _j ^oAnd according to the enthalpy h that draws gas of the shell-side under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode _Nj ^o,

By well heater steam cooling section thermal balance equation:

Pure condensate knot 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 _Ssj ^oBe the saturated air enthalpy of j level heater case wall pressure correspondence, 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 ℃;

Obtain the middle transition temperature t of steam cooling section and pure condensate knot section after the arrangement _Wsj ^oRelational expression with well heater water inlet, leaving water temperature:

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

Step 2: the heat compensator conducting property coefficient that calculates well heater steam cooling section under the benchmark operating mode

By steam cooling section heat transfer equation under the benchmark operating mode:

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

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

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

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

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

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, extraction temperature t _j, 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 _Sj, saturated air enthalpy h _SsjAnd saturation water enthalpy h _Swj, as if the extraction 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 _j, then by calculating the extraction temperature t under the actual condition _j, 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%;

The t of the extraction temperature under the described calculating actual condition _jMethod be:

Make under the actual condition shell-side enthalpy h that draws gas _NjBe taken as shell-side under the benchmark operating mode enthalpy h that draws gas _Nj ^o, shell-side enthalpy and shell-side under the benchmark operating mode enthalpy that draws gas that draws gas equates substantially under the variable working condition, again according to the industrial water and steam thermodynamic properties of IAPWS-IF97 model, by the shell-side enthalpy h that draws gas _NjWith the shell pressure p under the actual condition _NjCan calculate the extraction temperature t under the actual condition _j

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,

Step 3.2: the iterative computation of leaving water temperature and step thereof:

Leaving water temperature t under the actual condition is set _WjIterative initial value, get the well heater inflow temperature t under the actual condition _{W (j+1)}+ 15 as iteration initial value (t _Wj) _K=0, wherein subscript k is an iterations;

By leaving water temperature t _Wj(hypothesis) calculation of steam cooling section and pure condensate knot section middle transition temperature:

${\left(t_{\mathrm{wsj}}\right)}_k=\frac{{\left(t_{\mathrm{wj}}\right)}_k+t_{w(j+1)}\·(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})}{(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})+1}---\left(1\right)$

Can calculate middle transition temperature (t _Wsj) _kThen according to steam cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, calculate well heater heat compensator conducting property coefficient under the actual condition by the power of the assembling unit of benchmark operating mode respective heater steam cooling section heat compensator conducting property coefficient and actual condition, finally according to the leaving water temperature under this heat compensator conducting property coefficient and the middle transition temperature computation actual condition:

${\left(t_{\mathrm{wj}}\right)}_{k+1}=\frac{t_j-t_{\mathrm{sj}}}{\ln \frac{t_j-{\left(t_{\mathrm{wj}}\right)}_k}{t_{\mathrm{sj}}-t_{\mathrm{wsj}}}/[{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{SC}}^o\·{\left(\frac{P_e}{P_e^o}\right)}^m]+1}+{\left(t_{\mathrm{wsj}}\right)}_k---\left(2\right)$

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, for high-pressure heater m=0.6, for low-pressure heater m=0.3,

If current leaving water temperature (t _Wj) _kDo not meet the condition of convergence and then leaving water temperature newly is worth substitution formula (1) continuation iteration, described iteration convergence condition is: Δ t _Wj=| (t _Wj) _K+1-(t _Wj) _k|≤0.01,

Satisfy the current leaving water temperature (t of the iterative computation condition of convergence _Wj) _K+1Leaving water temperature t as well heater _WjEnd value,

Step 3.3: the calculating of drain temperature:

By a well heater pure condensate knot section phase-change heat transfer mechanism, draw gas that to keep temperature in the condensation heat transfer process be saturation temperature under the shell pressure, draw drain temperature t _DjEqual the saturation temperature t under the shell pressure _Sj

The invention has the advantages that:

The present invention is based on heat-transfer mechanism and can survey parameter with operation, the well heater steam cooling section of carrying vapour refrigeratory and the heat compensator conducting property coefficient of pure condensate knot section have been defined, and utilize the rule of the steam cooling section of newfound carrying vapour refrigeratory bleeder heater and pure condensate knot section heat compensator conducting property coefficient random groups variable power, a kind of indirect, simple and direct, method that high precision is calculated based on well heater water outlet of carrying vapour refrigeratory and drain temperature in the heat compensator conducting property coefficient measuring and calculating fired power generating unit heat regenerative system proposed.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 steam cooling section and pure condensate knot 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 can be, thereby improved well heater water outlet and drain temperature measuring reliability with the measurement certainty equivalence of well heater water outlet and drain temperature in extraction pressure and unit load measuring reliability.

Description of drawings

Fig. 1 is the principled thermal system figure of the surface heater of carrying vapour refrigeratory

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 carrying vapour refrigeratory and drain temperature measuring method is characterized in that,

Step 1: the mid-transition point temperature t of well heater steam cooling section and pure condensate knot section under the calculating benchmark operating mode _Wsj ^o:

Choose unit rated power 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, and choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure p _Nj ^o, extraction temperature t _j ^o, the shell-side enthalpy h that draws gas _Nj ^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 shell pressure p under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode _Nj ^oCorresponding saturation temperature t _Sj ^o, saturated air enthalpy h _Ssj ^oAnd saturation water enthalpy h _Swj ^o, by the shell pressure p under the benchmark operating mode _Nj ^o, extraction temperature t _j ^oAnd according to the enthalpy h that draws gas of the shell-side under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode _Nj ^o,

By well heater steam cooling section thermal balance equation:

Pure condensate knot 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 _Ssj ^oBe the saturated air enthalpy of j level heater case wall pressure correspondence, 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 ℃;

Obtain the middle transition temperature t of steam cooling section and pure condensate knot section after the arrangement _Wsj ^oRelational expression with well heater water inlet, leaving water temperature:

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

Step 2: the heat compensator conducting property coefficient that calculates well heater steam cooling section under the benchmark operating mode

By steam cooling section heat transfer equation under the benchmark operating mode:

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

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

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

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

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

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, extraction temperature t _j, 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 _Sj, saturated air enthalpy h _SsjAnd saturation water enthalpy h _Swj, as if the extraction 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 _j, then by calculating the extraction temperature t under the actual condition _j, 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%;

The t of the extraction temperature under the described calculating actual condition _jMethod be:

Make under the actual condition shell-side enthalpy h that draws gas _NjBe taken as shell-side under the benchmark operating mode enthalpy h that draws gas _Nj ^o, shell-side enthalpy and shell-side under the benchmark operating mode enthalpy that draws gas that draws gas equates substantially under the variable working condition, again according to the industrial water and steam thermodynamic properties of LAPWS-IF97 model, by the shell-side enthalpy h that draws gas _NjWith the shell pressure p under the actual condition _NjCan calculate the extraction temperature t under the actual condition _j

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,

Step 3.2: the iterative computation of leaving water temperature and step thereof:

Leaving water temperature t under the actual condition is set _WjIterative initial value, get the well heater inflow temperature t under the actual condition _{W (j+1)}+ 15 as iteration initial value (t _Wj) _K=0, wherein subscript k is an iterations;

By leaving water temperature t _Wj(hypothesis) calculation of steam cooling section and pure condensate knot section middle transition temperature:

${\left(t_{\mathrm{wsj}}\right)}_k=\frac{{\left(t_{\mathrm{wj}}\right)}_k+t_{w(j+1)}\·(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})}{(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})+1}---\left(1\right)$

Can calculate middle transition temperature (t _Wsj) _lThen according to steam cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, calculate well heater heat compensator conducting property coefficient under the actual condition by the power of the assembling unit of benchmark operating mode respective heater steam cooling section heat compensator conducting property coefficient and actual condition, finally according to the leaving water temperature under this heat compensator conducting property coefficient and the middle transition temperature computation actual condition:

${\left(t_{\mathrm{wj}}\right)}_{k+1}=\frac{t_j-t_{\mathrm{sj}}}{\ln \frac{t_j-{\left(t_{\mathrm{wj}}\right)}_k}{t_{\mathrm{sj}}-t_{\mathrm{wsj}}}/[{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{SC}}^o\·{\left(\frac{P_e}{P_e^o}\right)}^m]+1}+{\left(t_{\mathrm{wsj}}\right)}_k---\left(2\right)$

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, for high-pressure heater m=0.6, for low-pressure heater m=0.3,

If current leaving water temperature (t _Wj) _kDo not meet the condition of convergence and then leaving water temperature newly is worth substitution formula (1) continuation iteration, described iteration convergence condition is: Δ t _Wj=| (t _Wj) _K+1-(t _Wj) _k|≤0.01,

Satisfy the current leaving water temperature (t of the iterative computation condition of convergence _Wj) _K+1Leaving water temperature t as well heater _WjEnd value,

Step 3.3: the calculating of drain temperature:

By a well heater pure condensate knot section phase-change heat transfer mechanism, draw gas that to keep temperature in the condensation heat transfer process be saturation temperature under the shell pressure, draw drain temperature t _DjEqual the saturation temperature t under the shell pressure _Sj

With certain 300MW unit is example, realizes the water outlet of carrying vapour refrigeratory well heater in the Steam Turbine Regenerative System and the measuring and calculating of drain temperature.The #1 well heater of this unit is the high-pressure heater of carrying vapour refrigeratory.

The detailed calculated step is as follows:

(1), the mid-transition point temperature t of well heater steam cooling section and pure condensate knot section under the calculating benchmark operating mode _Ws1 ^o:

The design conditions of choosing unit rated power are the benchmark operating mode, and the shell pressure p of #1 well heater is arranged according to design parameter _N1 ^oBe 5.712MPa, the shell-side enthalpy h that draws gas _N1 ^oBe 3136.3kJ/kg, leaving water temperature t _W1 ^oBe 272.1 ℃, inflow temperature t _W2 ^oIt is 242.5 ℃.Saturation temperature t according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation shell pressure correspondence _S1 ^oBe 272.4 ℃, saturated air enthalpy h _Ss1 ^oBe 2787.6kJ/kg, saturation water enthalpy h _Sw1 ^oBe 1197.3kJ/kg.

(2), calculate the heat compensator conducting property coefficient of well heater steam cooling section under the benchmark operating mode

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

(3), calculate the leaving water temperature t of well heater under the actual condition _W1With drain temperature t _D1:

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 shell pressure p _N1Be 4.28MPa, the shell-side enthalpy h that draws gas _N1Be taken as the analog value 3136.3kJ/kg under the benchmark operating mode, well heater inflow temperature t _W2It is 226.2 ℃.Go out shell pressure p according to the industrial water and steam thermodynamic properties of IAPWS-IF97 Model Calculation _N1Corresponding saturation temperature t _S1Be 249.55 ℃, saturated air enthalpy h _Ss5Be 2799.4kJ/kg, saturation water enthalpy h _Sw5Be 1107.2kJ/kg.

Well heater inflow temperature t is set _W2+ 15=241.2 ℃ is leaving water temperature t _W1Iterative initial value.

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

${\left(t_{\mathrm{ws}1}\right)}_k=\frac{{\left(t_{w1}\right)}_k+{\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="HSA00000088221400011.png"\; state="\{\{state\}\}">t</figure-callout>}}_w\&CenterDot;(h_{n1}-h_{\mathrm{ss}1})/(h_{\mathrm{ss}1}-h_{\mathrm{sw}1})}{(h_{n1}-h_{\mathrm{ss}1})/(h_{\mathrm{ss}1}-h_{\mathrm{sw}1})+1}$

${\left(t_{w1}\right)}_{k+1}=\frac{t_1-{\mathrm{<figure-callout\; id="1"\; label="t\; s"\; filenames="HSA00000088221400011.png"\; state="\{\{state\}\}">t</figure-callout>}}_s}{\ln \frac{t_1-{\left(t_{w1}\right)}_k}{t_{s1}-{\mathrm{<figure-callout\; id="1"\; label="t\; ws"\; filenames="HSA00000088221400011.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{ws}}}/[{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{SC}1}^o\&CenterDot;{\left(\frac{P_e}{P_e^o}\right)}^{0.6}]+1}+{\left(t_{\mathrm{ws}1}\right)}_k$

Through 9 iteration, finally calculate the leaving water temperature t of well heater _W1Be 257.57 ℃, with measured value 254.2 relative errors be :-1.325%.

By pure condensate knot section phase-change heat transfer mechanism, drain temperature t _D1Equal saturation temperature t _S1, be 249.55 ℃, with the relative error of 249.55 ℃ of measured values be 0.000%.

Claims (1)

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

Step 1: the mid-transition point temperature of well heater steam cooling section and pure condensate knot section under the calculating benchmark operating mode

Choose unit rated power 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, and choose the thermal parameter of j level well heater under the benchmark operating mode: shell pressure

Extraction temperature

The shell-side enthalpy that draws gas

Leaving water temperature

Inflow temperature

And the power of the assembling unit And according to shell pressure under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode

Corresponding saturation temperature

The saturated air enthalpy

And saturation water enthalpy By the shell pressure under the benchmark operating mode

Extraction temperature

And according to the enthalpy that draws gas of the shell-side under the industrial water and steam thermodynamic properties of the IAPWS-IF97 Model Calculation benchmark operating mode

By well heater steam cooling section thermal balance equation:

Pure condensate knot 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;

Be the j level well heater amount of drawing gas, unit is kg/h;

Be the j level well heater shell-side enthalpy that draws gas, unit is kJ/kg;

Be the saturated air enthalpy of j level heater case wall pressure correspondence, unit is kJ/kg;

Be the saturation water enthalpy of j level heater case wall pressure correspondence, unit is kJ/kg;

Be 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 ℃);

Be the leaving water temperature of j level well heater, unit is ℃;

Be the inflow temperature of j level well heater, unit is ℃;

Obtain the middle transition temperature of steam cooling section and pure condensate knot section after the arrangement

Relational expression with well heater water inlet, leaving water temperature:

$t_{\mathrm{wsj}}^o=\frac{t_{\mathrm{wj}}^o+t_{w(j+1)}^o\&CenterDot;(h_{\mathrm{nj}}^o-h_{\mathrm{ssj}}^o)/(h_{\mathrm{ssj}}^o-h_{\mathrm{swj}}^o)}{(h_{\mathrm{nj}}^o-h_{\mathrm{ssj}}^o)/(h_{\mathrm{ssj}}^o-h_{\mathrm{swj}}^o)+1},$

Step 2: the heat compensator conducting property coefficient that calculates well heater steam cooling section under the benchmark operating mode

By steam cooling section heat transfer equation under the benchmark operating mode:

Wherein: subscript " SC " expression is the steam cooling section,

Be the product of steam cooling section Coefficient K under the benchmark operating mode and heat transfer area F, unit is kJ/ (m ²℃ h) m ²

Be steam cooling section feedwater flow D under the benchmark operating mode _wSpecific heat at constant pressure C with feedwater _pProduct, unit is kg/hkJ/ (kg a ℃);

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

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

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

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, extraction temperature t _j, 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 _Sj, saturated air enthalpy h _SsjAnd saturation water enthalpy h _Swj, as if the extraction 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 _j, then by calculating the extraction temperature t under the actual condition _j, 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%;

The t of the extraction temperature under the described calculating actual condition _jMethod be:

Make under the actual condition shell-side enthalpy h that draws gas _NjBe taken as shell-side under the benchmark operating mode enthalpy that draws gas

Shell-side enthalpy and shell-side under the benchmark operating mode enthalpy that draws gas that draws gas equates substantially under the variable working condition, again according to the industrial water and steam thermodynamic properties of IAPWS-IF97 model, by the shell-side enthalpy h that draws gas _NjWith the shell pressure p under the actual condition _NjCan calculate the extraction temperature t under the actual condition _j

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,

Step 3.2: the iterative computation of leaving water temperature and step thereof:

Leaving water temperature t under the actual condition is set _WjIterative initial value, get the well heater inflow temperature t under the actual condition _{W (j+1)}+ 15 as iteration initial value (t _Wj) _K=0, wherein subscript k is an iterations;

By leaving water temperature t _WjCalculation of steam cooling section and pure condensate knot section middle transition temperature:

${\left(t_{\mathrm{wsj}}\right)}_k=\frac{{\left(t_{\mathrm{wj}}\right)}_k+t_{w(j+1)}\&CenterDot;(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})}{(h_{\mathrm{nj}}-h_{\mathrm{ssj}})/(h_{\mathrm{ssj}}-h_{\mathrm{swj}})+1}---\left(1\right)$

Calculate middle transition temperature (t _Wsj) _lThen according to steam cooling section HEAT TRANSFER LAW, numerical experimentation with based on the identification of Model Parameters algorithm of sample, calculate well heater heat compensator conducting property coefficient under the actual condition by the power of the assembling unit of benchmark operating mode respective heater steam cooling section heat compensator conducting property coefficient and actual condition, finally according to the leaving water temperature under this heat compensator conducting property coefficient and the middle transition temperature computation actual condition:

${\left(t_{\mathrm{wj}}\right)}_{k+1}=\frac{t_j-t_{\mathrm{sj}}}{\ln \frac{t_j-{\left(t_{\mathrm{wj}}\right)}_k}{t_{\mathrm{sj}}-t_{\mathrm{wsj}}}/[{\left(\frac{\mathrm{KF}}{D_w{C}_p}\right)}_{\mathrm{SC}}^o\&CenterDot;{\left(\frac{P_e}{P_e^o}\right)}^m]+1}+{\left(t_{\mathrm{wsj}}\right)}_k---\left(2\right)$

Wherein: m is the power of the assembling unit P under the actual condition _eWith the power of the assembling unit under the benchmark operating mode

The index of ratio, for high-pressure heater m=0.6, for low-pressure heater m=0.3,

If current leaving water temperature (t _Wj) _kDo not meet the condition of convergence and then leaving water temperature newly is worth substitution formula (1) continuation iteration, described iteration convergence condition is: Δ t _Wj=| (t _Wj) _K+1-(t _Wj) _k|≤0.01,

Satisfy the current leaving water temperature (t of the iterative computation condition of convergence _Wj) _K+1Leaving water temperature t as well heater _WjEnd value,

Step 3.3: the calculating of drain temperature:

By a well heater pure condensate knot section phase-change heat transfer mechanism, draw gas that to keep temperature in the condensation heat transfer process be saturation temperature under the shell pressure, draw drain temperature t _DjEqual the saturation temperature t under the shell pressure _Sj

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