CN101650376B - Pure water hydrogen conductivity temperature compensation method of power plant - Google Patents

Abstract

The invention discloses a pure water hydrogen conductivity temperature compensation method of a power plant. A corresponding relationship among different ion concentrations in pure water, molar conductivity at infinite dilution, water ion product constant and conductivity is established through the law of independent migration of ions. The invention comprises the following steps: obtaining constants under different temperatures by testing the conductivity under actual temperatures and checking a data table, calculating corresponding ion concentrations, and substituting corresponding constants under 25 DEG C to obtain the value of the hydrogen conductivity after compensation. The invention improves the accuracy of hydrogen conductivity test under different temperatures. When the temperature is lower or higher than the standard temperature by 10 DEG C, in usual conditions, the error is within 14%-27% by conventional temperature compensation methods while the error can be controlled lower than 2% by the method in the invention.

Description

Pure water hydrogen conductivity temperature compensation method of power plant

Technical field

The present invention relates to a kind of temperature compensation of pure water hydrogen conductivity instrument, particularly pure water hydrogen conductivity temperature compensation method of power plant.

Background technology

When the generating plant pure water hydrogen conductivity was measured, measurement result was relevant with temperature, and the displayed value of hydrogen conductivity instrument must could reflect real water quality condition through after the temperature compensation.Existing hydrogen conductivity measurement result analytical error as calculated reaches 14%-27%, and the actual conditions of judging generating plant water quality successively will cause the corrosion aggravation of therrmodynamic system or cause economically loss.

The Chinese patent retrieval finds no the patent of closing pure water hydrogen conductivity temperature compensation.Literature search finds to have certain paper to propose to adopt the simplest model that temperature compensation is carried out in the pure water hydrogen conductivity measurement.There are two subject matters in this temperature compensation: (1) calculated with mathematical model process mistake; (2) this model and actual water quality difference are very big, no practical value.Be respectively described below:

In this article, when measuring, pure water hydrogen conductivity only contains H in the water sample ⁺, OH ^-, Cl ^-, set up system of equations (1) according to the relation equation that the law of the independent migration of ions in ion-product constant equation, anion-cation balance equation and the infinite dilution aqueous solution of water is set up between conductivity and each ion concentration.

$\left\{\begin{array}{c}{K}_w=C_{H^{+}}\·C_{{\mathrm{OH}}^{-}}\\ C_{H^{+}}=C_{{\mathrm{Cl}}^{-}}+C_{{\mathrm{OH}}^{-}}\\ {\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{{\mathrm{Cl}}^{-}}{C}_{{\mathrm{Cl}}^{-}}\end{array}\right.---\left(1\right)$

In the set of equations (1), K _w, κ _t,

Under corresponding temperature, be constant.In the actual measurement process, at first record the arbitrary temp and the corresponding conductivity value of acid solute infinite dilution aqueous solution by conductivity meter; Then, substitution set of equations (1) calculates three unknown quantitys to be had

Above-mentioned steps author has done detailed argumentation in the article that it is delivered, but mistake has taken place his next procedure: the 3rd formula in the direct substitution set of equations of three concentration values (1) that will calculate found the solution, in this up-to-date style

Get 25 ℃ respective value, obtain corresponding 25 ℃ conductivity.What should particularly point out is that above-mentioned steps is invalid in theory, the reasons are as follows: under the arbitrary temp, and during the conductivity value of known correspondence, H ⁺, OH ^-, Cl ^-Concentration be certain value, but when temperature changes, Cl ^-Concentration still remain unchanged, and because the relevant H that causes of ion-product constant of water with temperature ⁺, OH ^-Concentration will change with temperature.

In fact in the generating plant hydrogen conductivity measuring process, water sample shows acid usually through hydrogen ion exchange back, comprises following ion: H ⁺, OH ^-, Cl ^-, SO ₄ ^2-, NO ₃ ^-, F ^-, CH ₃COO ^-, HCOO ^-, PO ₄ ^3-Deng.Only comprise H in the above-mentioned model ⁺, OH ^-, Cl ^-Three kinds of ions, all the other anionic infinite dilution molar conductivity and Cl in addition ^-Difference, especially CH ₃COO ^-, HCOO ^-The infinite dilution molar conductivity of ion only is Cl ^-About 1/2.Therefore the precondition of above-mentioned modelling is with actual quite different.

Summary of the invention

The purpose of this invention is to provide a kind of pure water hydrogen conductivity temperature compensation method of power plant, this method solves Temperature Compensation problem in the generating plant pure water hydrogen conductivity measuring process.

Technical scheme of the present invention is achieved in that

At first, set up and the corresponding tables of data of each power plant's actual conditions, this table reflects is temperature and the ionic product K of corresponding water _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity The infinite dilution molar conductivity of hydroxide ion Between relation; The method for building up of tables of data is as follows: be row with the temperature t, 1 ℃ of every row temperature interval is with the ionic product K of the water under the corresponding temperature _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity The infinite dilution molar conductivity of hydroxide ion

For row-column list both got;

K wherein _w,

By consult " Lan Shi chemistry handbook can be found,

Definite method as follows: earlier measure ion concentration through the water sample after the exchange of hydrogen ion exchange column by ion chromatograph; Then, calculate ion infinite dilution molar conductivity under the corresponding temperature according to equation (3);

${\mathrm{\λ}}_{M^{-}}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\λ}}_{{\mathrm{Mi}}^{-}}{C}_{{\mathrm{Mi}}^{-}}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_{{\mathrm{Mi}}^{-}}}---\left(3\right)$

In the formula,

Anionic ion infinite dilution molar conductivity constant when the expression temperature t is 10-50 ℃;

Be anion concentration; M ^-Negative ion in the expression water;

Secondly, according to three unknown quantitys of set of equations (2) when calculating temperature t, pH

Hydroxide ion concentration

Anion concentration

During calculating, other known quantities all by looking into tables of data, adopt the temperature t respective value;

$\left\{\begin{array}{c}{K}_w=C_{H^{+}}\·C_{{\mathrm{OH}}^{-}}\\ C_{H^{+}}=C_{M^{-}}+C_{{\mathrm{OH}}^{-}}\\ {\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{M^{-}}{C}_{M^{-}}\end{array}\right.---\left(2\right)$

In the formula, κ _tThe conductivity value of actual measurement during the expression temperature t;

Hydrogen conductivity when at last, calculating 25 ℃: the acidic anionic concentration of having calculated during fixed temperature t

Constant, under 25 ℃, find the solution the ion-product constant of water when need to adopt 25 ℃ this moment, correspondence during 25 ℃ of can obtain drawing by above calculating again according to preceding two equations of set of equations (2)

With Concentration, and then the 3rd formula in the substitution set of equations (2):

${\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{M^{-}}{C}_{M^{-}}$

This moment, all the other each parameters adopted the value of 25 ℃ of correspondences by looking into tables of data when calculating, and found the solution the hydrogen conductivity value that promptly get under 25 ℃ of the correspondences after the temperature compensation.

Above-mentioned generating plant pure water hydrogen conductivity is measured temperature compensation and has been improved the accuracy that hydrogen conductivity is measured under the different temperatures.When temperature and reference temperature differed 10 ℃, generally, conventional temperature compensation error was between 14%-27%, and method error that the present invention adopts can be controlled within 2%.

Embodiment

Principle of the present invention is as follows: according to Cole Louth (Kohlrausch) law is that law of the independent migration of ions is set up the ion-product constant of different ions concentration in the pure water, infinite dilution molar conductivity and water and the corresponding relation between the conductivity.Draw each constant under the different temperatures by measuring the conductivity under the actual temperature and tabling look-up, calculate each corresponding ion concentration, the hydrogen conductivity value after the compensation is tried to achieve in corresponding constant substitution with 25 ℃ the time.

The mentioned pure water hydrogen conductivity temperature compensation method of power plant of the present invention can be realized in the following manner: at first all related constants of equation are kept in the computing module of conductivity meter, these constants can obtain by consulting relevant chemical handbook and test, often need call in the temperature compensation process; Secondly the numerical value of acidic anionic infinite dilution molar conductivity is shown as the function of acidic anionic concentration in the water according to certain algorithm table, after water sample being carried out the trace ion analysis at every turn, with the analysis result input, calculate the numerical value of corresponding acidic anionic infinite dilution molar conductivity then; The system of equations programming of then that the present invention is mentioned compensation mathematical model is solidificated in the computing module of conductivity meter.

During actual measurement, at first record temperature and the corresponding temperature that records when uncompensated under conductivity value; The numerical value that calls constant and acidic anionic infinite dilution molar conductivity then carries out computing, and three unknown quantitys that obtain under this temperature have

At last, the acid ion M that has fixedly calculated under the arbitrary temp ^-Concentration is constant, finds the solution the ion-product constant of water when need to adopt 25 ℃ this moment again under 25 ℃ according to preceding two equations of set of equations (2).Correspondence can obtain drawing by above calculating 25 ℃ times

With After the concentration, the 3rd formula in the substitution set of equations again (2) found the solution the hydrogen conductivity value that promptly gets after the temperature compensation.

When the generating plant hydrogen conductivity is measured, the kind of water intermediate ion is relevant with the water technology that power plant is adopted, adopt the generating plant of conventional ion exchange system, especially cogeneration plant, because organism decomposes the weak acid electrolyte that brings hydrogen conductivity is had very large influence in therrmodynamic system, be the one of the main reasons that causes hydrogen conductivity to exceed standard.Often contain a large amount of weak acid anions in the detected water sample, especially with CH ₃COO ^-Ion is main; And adopt the generating plant of full membrane method water treatment system, and not containing weak acid anion in the detected water sample substantially, the impurity negative ion is mainly strong acid anion.Under above-mentioned two kinds of situations, all can adopt acidic anionic applied temps compensation mathematical model to solve.

$\left\{\begin{array}{c}{K}_w=C_{H^{+}}\·C_{{\mathrm{OH}}^{-}}\\ C_{H^{+}}=C_{M^{-}}+C_{{\mathrm{OH}}^{-}}\\ {\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{M^{-}}{C}_{M^{-}}\end{array}\right.---\left(2\right)$

The 3rd equation of system of equations (2) acidic anionic molar conductivity arithmetic mean

Replaced the Cl in system of equations (1) simple mathematical model ^-The molar conductivity of ion is used acidic anionic concentration

Replaced Cl ^-Anionic concentration

The temperature compensation compensation process of actual measurement process is as follows:

At first, set up and the corresponding tables of data of each power plant's actual conditions, this table reflects is temperature and the ionic product K of corresponding water _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity

The infinite dilution molar conductivity of hydroxide ion

Between relation.The method for building up of tables of data is as follows: be row with the temperature t, 1 ℃ of every row temperature interval is with the ionic product K of the water under the corresponding temperature _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity The infinite dilution molar conductivity of hydroxide ion

For row-column list both got.K wherein _w,

" Lan Shi chemistry handbook can be found by consulting. Definite method as follows: earlier measure ion concentration through the water sample after the exchange of hydrogen ion exchange column by ion chromatograph; Then, calculate ion infinite dilution molar conductivity under the corresponding temperature according to equation (3);

${\mathrm{\λ}}_{M^{-}}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\λ}}_{{\mathrm{Mi}}^{-}}{C}_{{\mathrm{Mi}}^{-}}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_{{\mathrm{Mi}}^{-}}}---\left(3\right)$

In the formula,

Anionic ion infinite dilution molar conductivity constant when the expression temperature t is 10-50 ℃; Be anion concentration; M ^-Negative ion in the expression water.

Secondly, according to three unknown quantitys of set of equations (2) when calculating temperature t, pH Hydroxide ion concentration Anion concentration

During calculating, other known quantities all by looking into tables of data, adopt the temperature t respective value.

$\left\{\begin{array}{c}{K}_w=C_{H^{+}}\·C_{{\mathrm{OH}}^{-}}\\ C_{H^{+}}=C_{M^{-}}+C_{{\mathrm{OH}}^{-}}\\ {\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{M^{-}}{C}_{M^{-}}\end{array}\right.---\left(2\right)$

In the formula, κ _tThe conductivity value of actual measurement during the expression temperature t.

Hydrogen conductivity when at last, calculating 25 ℃.The acidic anionic concentration of having calculated during fixed temperature t

Constant, under 25 ℃, find the solution the ion-product constant of water when need to adopt 25 ℃ this moment again according to preceding two equations of set of equations (2).Correspondence can obtain drawing by above calculating 25 ℃ times With Concentration, and then the 3rd formula in the substitution set of equations (2):

${\mathrm{\κ}}_t={\mathrm{\λ}}_{H^{+}}{C}_{H^{+}}+{\mathrm{\λ}}_{{\mathrm{OH}}^{-}}{C}_{{\mathrm{OH}}^{-}}+{\mathrm{\λ}}_{M^{-}}{C}_{M^{-}}$

This moment, all the other each parameters adopted the value of 25 ℃ of correspondences by looking into tables of data when calculating.Find the solution and promptly get the hydrogen conductivity value under corresponding 25 ℃ after the temperature compensation.

Claims (1)

1. pure water hydrogen conductivity temperature compensation method of power plant is characterized in that, may further comprise the steps:

At first, set up and the corresponding tables of data of each power plant's actual conditions, this table reflects is temperature and the ionic product K of corresponding water _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity

The infinite dilution molar conductivity of hydroxide ion Between relation; The method for building up of tables of data is as follows: be row with the temperature t, 1 ℃ of every row temperature interval is with the ionic product K of the water under the corresponding temperature _w, anionic infinite dilution molar conductivity

Hydrionic infinite dilution molar conductivity The infinite dilution molar conductivity of hydroxide ion

For row-column list promptly;

K wherein _w,

By consult " Lan Shi chemistry handbook can be found, Definite method as follows: earlier measure ion concentration through the water sample after the exchange of hydrogen ion exchange column by ion chromatograph; Then, calculate ion infinite dilution molar conductivity under the corresponding temperature according to equation (3);

In the formula,

Anionic ion infinite dilution molar conductivity constant when the expression temperature t is 10-50 ℃;

Be anion concentration; M ^-Negative ion in the expression water;

Secondly, according to three unknown quantitys of set of equations (2) when calculating temperature t, pH

Hydroxide ion concentration

Anion concentration

During calculating, other known quantities all by looking into tables of data, adopt the temperature t respective value;

In the formula, κ _tThe conductivity value of actual measurement during the expression temperature t;

Hydrogen conductivity when at last, calculating 25 ℃: the anion concentration that has calculated during fixed temperature t Constant, under 25 ℃, find the solution the ion-product constant of water when need to adopt 25 ℃ this moment, correspondence during 25 ℃ of can obtain drawing by above calculating again according to preceding two equations of set of equations (2)

With

Concentration, and then the 3rd formula in the substitution set of equations (2):

This moment, all the other each parameters adopted the value of 25 ℃ of correspondences by looking into tables of data when calculating, and found the solution the hydrogen conductivity value that promptly get under 25 ℃ of the correspondences after the temperature compensation.