CN105241667A - Condenser vacuum state identification method based on k-M model - Google Patents

Abstract

The invention relates to a condenser vacuum state identification method based on a k-M model. Based on limited test data, the function relationship between the normal heat transfer coefficient (i)kc(/i) of a condenser and a dimensionless parameter (i)M(/i) is established. The normal heat transfer coefficient (i)kc(/i) of the condenser under any operating condition of a unit is determined. By comparing the deviation between the normal heat transfer coefficient and an actual heat transfer coefficient, when the vacuum of the condenser is normal is judged. Compared with the prior art, the method provided by the invention has the advantages that the method is for a given actual unit; a user does not need to know the specific structure size of the condenser; and the limited test data of a stable operating condition are used to determine whether the vacuum of the condenser is normal under any stable operating condition is normal.

Description

Based on the condenser vacuum condition discrimination method of k-M model

Technical field

The present invention relates to a kind of condensing steam turbine generator group diagnostic techniques, particularly a kind of condenser vacuum condition discrimination method based on k-M model.

Background technology

Condenser and backup system thereof are Turbo-generator Set cold junctions, and the operation of its running status to Turbo-generator Set is significant, and the research and apply therefore about condenser operational diagnostics and optimization is paid attention to always widely.The prerequisite of condenser operational diagnostics and optimization judges that whether condenser vacuum is normal.All compare judge by actual measurement condenser pressure and condenser pressure being reached value when judging that condenser vacuum state whether rationally.The determination that condenser pressure should reach value generally has two class methods.

(1) classic method:

With condenser pressure P _ccorresponding saturated-steam temperature t _sdetermine by formula (1):

t _s＝t _w1+Δt+δt(1)

T in formula _w1for cooling water inlet temperature, Δ t is cooling water temperature rise, and δ t is condenser terminal difference.

When ignoring other heats entering condenser, the condensation heat amount of steam equals the caloric receptivity of chilled water, then the temperature rise of chilled water can be calculated by (2) formula:

$\mathrm{\Δ}t=\frac{D_c\·(h_c-{h_c}^{\′})}{D_w\·c_p}=\frac{D_c\·(h_c-{h_c}^{\′})}{4.187D_w}---\left(2\right)$

C in formula _pfor specific heat of water holds, D _wfor cooling water flow, D _cfor turbine discharge amount, h _cfor exhaust enthalpy of turbine, h _c' be condensate water enthalpy.

Condenser terminal difference can be calculated by (3) formula:

$\mathrm{\δ}t=\frac{\mathrm{\Δ}t}{e^{\frac{A\·k}{4.187D_w}}-1}---\left(3\right)$

In formula, A is the effective heat transfer area of condenser, and k is condenser heat transfer coefficient.In traditional defining method, in engineering, condenser heat transfer coefficient is determined often through experimental formula, the other Germania experimental formula of what at present application was wider is formula that U.S. thermal conduction study meeting (HEI) recommends, USSR (Union of Soviet Socialist Republics) thermal technology institute and Britain BEAMA formula.

Then after cooling water inlet temperature is determined, can by (1) formula determination condenser pressure P _ccorresponding saturated-steam temperature t _s, and then by (4) formula or look into water vapor table determination condenser pressure P _c.

$P_c=9.18\×{\left(\frac{t_s+100}{57.66}\right)}^{7.46}---\left(4\right)$

(2) intelligent diagnostics

Apply BP neural network, population BP neural network, determine norm vacuum based on intelligent algorithms such as vector machine recurrence, data fusion.Its input parameter has employing to use the method for multiple linear regression to judge to affect the large factor of condenser vacuum correlativity; Also there is after adopting the parameter-unit current power after being simplified by condenser pressure calculating mechanism, cooling water inlet temperature, condenser to clean the time, put into operation water circulating pump number of units etc.; Also have the turbine discharge, Inlet Temperature of Circulating Water, the circulating water flow that adopt.These methods need great amount of samples to train algorithm on the one hand, and what input parameter had on the other hand is difficult to direct measurement, and what have has coupling each other, and practical application is inconvenient.

Summary of the invention

The present invention be directed to the problem judging now condenser vacuum status method complexity, propose a kind of condenser vacuum condition discrimination method based on k-M model, a kind of simple and effective method is provided, determines condensing steam turbine generator group condenser in a certain operating mode (by unit load Pe, cooling water inlet temperature t _w1with cooling water flow D _wdetermine) under vacuum (or working pressure) whether normal.K-M model and the test relational expression between condenser heat transfer coefficient k and condenser operating condition correlation parameter M.

Technical scheme of the present invention is: a kind of condenser vacuum condition discrimination method based on k-M model, specifically comprises the steps:

1) relation between the normal heat transfer coefficient of condenser of given condensing steam turbine generator group and operating mode dimensionless number M is determined:

Carry out condenser performance test when given condensing steam turbine generator group normal operation, measurement data comprises unit load Pe, cooling water flow D _w, condenser pressure p _c, cooling water inlet temperature t _w1and outlet water temperature t _w2, and by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s, substitute into formula below and try to achieve the normal heat transfer coefficient k of condenser _c,

$k_c=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}$

Wherein A _cfor the heat interchanging area of condenser;

Definition condenser operating condition correlation parameter is

Data by experiment, the normal heat transfer coefficient k of matching condenser _cwith the pass between M is:

k _c＝a·M ^b

Wherein a, b are and cooling water flow D _wrelevant coefficient, finally obtains matching k _cmaximum relative error be Δ;

2) given operating mode, i.e. unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1determination to fixing the normal heat transfer coefficient of condenser:

With unit load Pe, the cooling water inlet temperature t of given operating mode _w1, cooling water flow D _wcalculate dimensionless number M, normal heat transfer coefficient k after M being brought into matching _cformulae discovery can the normal heat transfer coefficient k of condenser under this operating condition _c;

3) in step 2) determination of the actual heat transfer coefficient of condenser under given operating mode:

At unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1and under given prerequisite, measure condenser pressure p _c, coolant outlet water temperature t _w2, by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s, and then try to achieve the actual heat transfer coefficient k of condenser _c',

${k_c}^{\′}=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}$

4) in step 2) whether condenser vacuum judges normally under given operating mode:

The deviation defining actual heat transfer coefficient and normal heat transfer coefficient is

If $\mathrm{\δ}=\frac{\left|{k_c}^{\′}-k_c\right|}{k_c}>1.1\mathrm{\Δ},$ Then condenser vacuum is abnormal; If $\mathrm{\δ}=\frac{\left|{k_c}^{\′}-k_c\right|}{k_c}\≤1.1\mathrm{\Δ},$ Then think that condenser vacuum is normal.

Beneficial effect of the present invention is: the condenser vacuum condition discrimination method that the present invention is based on k-M model, compared with prior art, the present invention is directed to given actual set, not must know the physical dimension that condenser is concrete, just can judge all operating modes of unit according to the test figure of limited nominal situation, make the judgement of condenser working condition more simple.

Accompanying drawing explanation

Fig. 1 is a typical condensing steam turbine generator group system schematic diagram of concrete measuring method of the present invention and application thereof.

Embodiment

An exemplary situations---the steam turbine generator set system of concrete measuring method of the present invention and application thereof as shown in Figure 1: steam 1 enters steam turbine 2 expansion work drive electrical generators 3 and generates electricity, steam discharge enters condenser 13, cooled water cooling becomes condensate water 12,9 is cooling water inlet pipeline, 8 is coolant outlet pipeline, and chilled water leaves condenser after heating up.Coolant outlet pipeline 8 arranges test point 7, detects coolant outlet water temperature t _w2, cooling water inlet pipeline 9 arranges two test points 10,11, detects cooling water inlet temperature t respectively _w1with cooling water flow D _w, the output terminal of generator 3 arranges test point 4, detects unit load Pe, and all numbers of test points are according to sending computing unit 6, and 5 is electromotive power output.The concrete steps of the inventive method are:

(1) relation between the normal heat transfer coefficient of certain unit condenser and operating mode dimensionless number M is determined:

For given condensing steam turbine generator group, in the normal situation of unit operation, carry out condenser performance test.Measurement data comprises unit load Pe, cooling water flow D _w, condenser pressure p _c, cooling water inlet temperature t _w1and outlet water temperature t _w2deng Specifeca tion speeification, and by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s.And then try to achieve the normal heat transfer coefficient k of condenser according to formula (5) _c.

$k_c=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}---\left(5\right)$

Wherein A _cfor the heat interchanging area of condenser.

Definition condenser operating condition correlation parameter is

Data by experiment, the normal heat transfer coefficient k of matching condenser _cwith the pass between M is

k _c＝a·M ^b(6)

Wherein a, b are and cooling water flow D _wrelevant coefficient, the maximum relative error of fitting formula is Δ.

(2) certain operating mode (i.e. unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1given) under the determination of the normal heat transfer coefficient of condenser:

According to unit load Pe, cooling water inlet temperature t _w1, cooling water flow D _wcalculate dimensionless number M;

M is brought into the normal heat transfer coefficient k that formula (6) can be calculated condenser under this operating condition _c.

(3) in above-mentioned (2) determine the determination of the actual heat transfer coefficient of condenser under operating mode:

At unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1under given prerequisite, measure condenser pressure p _c, coolant outlet water temperature t _w2deng Specifeca tion speeification, by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s.And then try to achieve the actual heat transfer coefficient k of condenser _c'.

${k_c}^{\′}=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}---\left(7\right)$

(4) fix condenser vacuum in above-mentioned (2) whether to judge normally:

The deviation defining actual heat transfer coefficient and normal heat transfer coefficient is

If $\mathrm{\δ}=\frac{\left|{k_c}^{\′}-k_c\right|}{k_c}>1.1\mathrm{\Δ},$ Then condenser vacuum is abnormal; If $\mathrm{\δ}=\frac{\left|{k_c}^{\′}-k_c\right|}{k_c}\≤1.1\mathrm{\Δ},$ Then think that condenser vacuum is normal.

This method calculates illustration:

1, known conditions

For the condenser of certain 1000MW Steam Turbine.The supporting condenser model of this unit is N-54000, and film-cooled heat is 54000m ².Due to chilled water configuration, cooling water flow only has a kind of 27.604kg/s.

2, k is determined according to accidental conditions test _cwith the relational expression of M

Under normal running (operation) conditions, measure the condenser service data under unit 5 operating modes with test method(s), as shown in table 1.And according to with calculate k _ctable 1 is listed in, wherein c with M value _pfor according to t _w1the specific heat of water determined holds.

Table 1

According to k _c=aM ^bthe normal heat transfer coefficient k of power function relationship matching _cwith the relational expression of M be: k _c=94.327M ^-1.1464

Maximum relative error Δ=1.412% of fitting formula

3, under monitoring condenser actual operating mode, determine that the deviation of the normal heat transfer coefficient of condenser and the actual heat transfer coefficient of condenser is as shown in table 2, cooling water flow is 27.604kg/s.

The wherein normal heat transfer coefficient k of condenser _c=94.327M ^-1.1464

The actual heat transfer coefficient of condenser ${k_c}^{\′}=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}.$

Table 2

Then the condenser heat transfer coefficient deviation of operating mode 1-3 is greater than 1.1 Δ=1.6%, belongs to the abnormal situation of condenser vacuum; And the condenser heat transfer coefficient deviation of operating mode 4 is less than 1.1 Δ=1.6%, condenser vacuum is normal.This conforms to actual conditions.

Claims (1)

1., based on a condenser vacuum condition discrimination method for k-M model, it is characterized in that, specifically comprise the steps:

1) relation between the normal heat transfer coefficient of condenser of given condensing steam turbine generator group and operating mode dimensionless number M is determined:

Carry out condenser performance test when given condensing steam turbine generator group normal operation, measurement data comprises unit load Pe, cooling water flow D _w, condenser pressure p _c, cooling water inlet temperature t _w1and outlet water temperature t _w2, and by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s, substitute into formula below and try to achieve the normal heat transfer coefficient k of condenser _c,

$k_c=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}$

Wherein A _cfor the heat interchanging area of condenser;

Definition condenser operating condition correlation parameter is

Data by experiment, the normal heat transfer coefficient k of matching condenser _cwith the pass between M is:

k _c＝a·M ^b

Wherein a, b are and cooling water flow D _wrelevant coefficient, finally obtains matching k _cmaximum relative error be Δ;

2) given operating mode, i.e. unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1determination to fixing the normal heat transfer coefficient of condenser:

With unit load Pe, the cooling water inlet temperature t of given operating mode _w1, cooling water flow D _wcalculate dimensionless number M, normal heat transfer coefficient k after M being brought into matching _cformulae discovery can the normal heat transfer coefficient k of condenser under this operating condition _c;

3) in step 2) determination of the actual heat transfer coefficient of condenser under given operating mode:

At unit load Pe, cooling water flow D _w, cooling water inlet temperature t _w1and under given prerequisite, measure condenser pressure p _c, coolant outlet water temperature t _w2, by table look-up or the mode of software obtains recirculated water specific heat capacity c under each operating mode _pwith the saturation pressure t under condenser pressure _s, and then try to achieve the actual heat transfer coefficient k of condenser _c',

${k_c}^{\′}=\frac{c_p\·D_w}{A_c}\·ln\frac{t_s-t_{w1}}{t_s-t_{w2}}$

4) in step 2) whether condenser vacuum judges normally under given operating mode:

The deviation defining actual heat transfer coefficient and normal heat transfer coefficient is

If then condenser vacuum is abnormal; If then think that condenser vacuum is normal.