CN101737312A - Independent low-pressure heater and drainage pump flow soft measurement-based method for measuring and calculating pump efficiency - Google Patents

Abstract

The invention relates to an independent low-pressure heater and drainage pump flow soft measurement-based method for measuring and calculating pump efficiency. A thermodynamic system of the invention consists of an independent low-pressure heater (LH) and a drainage pump. The method comprises the following steps of: acquiring the water pressure at the outlet of the heater with the drainage pump from a database of a heat-engine plant supervisor information system (SIS) or a decentralized control system (DCS); acquiring the water temperature at the inlet of the drainage pump; acquiring the real-time current and voltage, efficiency and power factor of a motor of the drainage pump; acquiring the water pressure at the inlet of the drainage pump and the drainage average specific volume through calculation; calculating the pressure difference of the drainage pump, namely the difference between the water pressure at the outlet of the heater with the drainage pump and the water pressure at the inlet of the drainage pump; calculating the flow of the drainage pump by using a method for measuring and calculating the flow of the independent low-pressure heater and drainage pump of a heat-engine machine set based on energy balance; figuring out the output power and the input power of the drainage pump according to the data; and calculating a ratio of the output power to the input power, namely the efficiency of the drainage pump.

Description

Method for measuring and calculating pump efficiency based on independent low-pressure heater and drainage pump flow soft measurement

Technical field

The present invention relates to a kind of method for measuring and calculating pump efficiency, belong to soft fields of measurement based on independent low-pressure heater and drainage pump flow soft measurement.

Background technique

Along with the expansion of fired power generating unit capacity, heat regenerative system more and more receives publicity to the influence of unit.In the bleeder heater, for improving the backheat effect of surface heater, low-pressure heater can have drainage pump usually.The measurement of drainage pump efficient all has material impact for the performance monitoring of drainage pump, the optimization operation of drainage pump, the running state analysis of Heater group and even the EQUILIBRIUM CALCULATION FOR PROCESS of heat regenerative system heat.Therefore be necessary drainage pump efficient is monitored.Yet there are no the measuring and calculating of drainage pump efficient and the report of drainage pump performance monitoring method.

At present, in plant level supervisory information system SIS of thermal power plant (Supervisory Information System) or the decentralized control system DCS of system (Distribution Control System), generally there is not drainage pump efficient measuring point.When the drainage pump input power is calculated, can't extract the instantaneous power value and have influence on hydrophobic measuring and calculating pump efficiency, and when the drainage pump output power is calculated, need the drainage pump flow be calculated, at present, in thermodynamic system, set up the drainage pump measuring point, need according to the performance requirement to it, fluid characteristics, installation requirement, environmental conditions and cost element wait selects suitable flowmeter.After setting up this measuring point, will there be certain influence, and needs the cost manpower and materials that it is safeguarded flow.Therefore, the problem that directly solves the drainage pump flow from hardware aspect takes time and effort, and has inconvenience.These are present in the measurement that problem in the drainage pump flow measurement has directly influenced the drainage pump output power.

Summary of the invention

The object of the present invention is to provide a kind of can economize on hardware and the method for measuring and calculating pump efficiency based on independent low-pressure heater and drainage pump flow soft measurement of memory source, this method can have low, the advantage of high precision of cost by the on-line monitoring of flexible measurement method realization to drainage pump efficient.

The present invention adopts following technological scheme to realize:

A kind of method for measuring and calculating pump efficiency based on independent low-pressure heater and drainage pump flow soft measurement was made up of independently low adding with a drainage pump, do not have other hydrophobic enter to hang down add.Wherein, utilize drainage pump that low plus hydrophobic is mixed with the low feedwater that adds outlet, algorithm steps is as follows,

Algorithm steps is as follows:

Step 1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain band drainage pump heater outlet water pressure p _wObtain the temperature t of the inlet water of drainage pump _p, calculate the inlet water pressure p of drainage pump _pAnd hydrophobic average specific volume

, calculate drainage pump pressure differential deltap p and be band drainage pump heater outlet water pressure p _wInlet water pressure p with drainage pump _pPoor, drainage pump flow D _pBy calculating, calculate drainage pump output power W based on drainage pump flow measuring method in the low adding system of fired power generating unit of energy balance _OutExpression:

Described drainage pump flow D _pAdopt following method to obtain:

Step 1-1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain the low inlet water temperature t that adds _WinAnd pressure p _Win, calculate inlet water enthalpy h _WinObtain the extraction temperature t of heater ₁, extraction pressure p ₁, calculate the enthalpy h that draws gas of heaters at different levels ₁Obtain the low outlet coolant-temperature gage t that adds _W1, pressure p _W1, calculate heater outlet water enthalpy h ' _W1Obtain the heater condensate temperature t _D1,, calculate heater condensate enthalpy h at different levels in conjunction with extraction pressure _D1, hydrophobic flow shares d _D1Expression;

Step 1-2: establish in the low drainage pump that adds hydrophobicly and low to add the mixed flow shares of saliva be 1, hang down that to add the inlet water flow shares be d _In, the 1st grade of hydrophobic flow shares is d _p, according to flow equilibrium relation, d _p=d _P1, heater outlet water enthalpy is h ' _W1, drainage pump outlet enthalpy is h _D1, the enthalpy behind the mixing point is h _W1

Step 1-3: set up the flow equilibrium equation:

d _in+d _p＝1

Set up mixing point heat Balance Calculation equation:

d _in*h’ _w1+d _p*h _d1＝1*h _w1

Set up heater heat transfer equation of equilibrium:

d _in*(h’ _w1-h _win)＝d ₁*(h ₁-h _d1)

And obtain the flow shares d of drainage pump thus _p:

$d_p=\frac{{\mathrm{\τ}}_1}{{\mathrm{\τ}}_1+q_1}$

Wherein, τ ₁=h ' _W1-h _Win, q ₁=h ₁-h _D1,

Step 1-4: according to the resulting hydrophobic flow shares d of step 3 _p, in conjunction with the water flow D with fixed attention among SIS or the DCS _nCheckout value calculates drainage pump flow D _p, D _p=d _p* D _n

Step 2: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain drainage pump configuration motor real-time current I real-time voltage U, and read drainage pump configuration electric efficiency η and power factor from drainage pump configuration motor nameplate Calculate drainage pump input power W _In:

Step 3: calculate the drainage pump efficiency eta _p:

The invention has the advantages that:

1, this paper drainage pump of inventing proposition is effectively exported the soft-sensing model of energy, and desired parameters generally all has corresponding thermal technology's measuring point in the SIS system, need not to add especially in addition measuring point and measure in system.

2, different with the conventional method of necessary measurement electric power in the efficient measuring and calculating, the present invention directly according to conventional electric current, voltage measuring value, has set up the input power soft-sensing model that satisfies engineering precision, has reduced the measurement cost.

3, based on the hydrophobic method for measuring and calculating pump efficiency of above-mentioned soft-sensing model, not only filled up the blank of hydrophobic measuring and calculating pump efficiency, also be a kind of low-cost solution.

4, adopting soft-sensing model, find the solution the drainage pump rate of discharge, is another significant advantage of the present invention.In the tradition flow measurement, for guaranteeing certain measuring accuracy, stability and reliability, need the measuring cell of complex and expensive, because the narrow limitation of drainage pump mounting point, the direct measurement of drainage pump efficient almost can't realize, the then not limited influence of soft measurement.

5, the drainage pump flow D of the present invention's employing _pComputational methods be that the present invention further has following advantage:

5-1, along with the expansion of China's generating set capacity, also become one of factor that guarantees unit safety and Economy as the performance monitoring of the drainage pump of supplementary equipment.At present, do not see the measuring and calculating of drainage pump flow and the report of drainage pump performance monitoring method.The drainage pump flow is the important parameter that can embody the drainage pump performance, the fired power generating unit heat regenerative system drainage pump flow measuring method based on energy balance that the present invention proposes has solved the problem of drainage pump performance monitoring, can effectively monitor in real time the drainage pump performance.

In 5-2, the traditional flow measurement, for guaranteeing certain measuring accuracy, stability and reliability, measuring cell need possess certain front and back main leg's length.To be Applied Computer Techniques measure or temporary transient immeasurable significant variable being difficult to the basic thought of soft measurement, and the variable of selecting other to measure is easily inferred or estimated by constituting certain mathematical relationship, comes the function of alternative hardware with software.Therefore soft measurement is not subjected to traditional flow measurement limitations affect, has not only saved cost, and has increased application area.Utilize existing measuring point parameter to calculate, made full use of existing resource; The error that the soft result of calculation that measures has avoided newly-increased measuring cell to bring has guaranteed measuring accuracy.Drainage pump outlet measuring water flow proposed by the invention belongs to soft-sensing model, and wherein desired parameters generally all has corresponding measuring point in SIS system or DCS system.Therefore, need not in system, to add especially in addition measuring point and measure, saved the expense of measuring cell and safeguarded cost, realized purpose cheaply.

Description of drawings

Fig. 1 is the schematic representation of drainage pump efficiency calculation.

Fig. 2 is the independent low schematic representation that makes up with drainage pump that adds.

Fig. 3 is a drainage pump flow rate calculation flow chart.

Fig. 4 is a calculation flow chart of the present invention.

Embodiment

A kind of method for measuring and calculating pump efficiency based on independent low-pressure heater and drainage pump flow soft measurement was made up of independently low adding with a drainage pump, do not have other hydrophobic enter to hang down add.Wherein, utilize drainage pump that the feedwater of the hydrophobic and heater outlet of heater is mixed, algorithm steps is as follows:

Step 1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain band drainage pump heater outlet water pressure p _wObtain the temperature t of the inlet water of drainage pump _p, calculate the inlet water pressure p of drainage pump _pAnd hydrophobic average specific volume

, calculate drainage pump pressure differential deltap p and be band drainage pump heater outlet water pressure p _wInlet water pressure p with drainage pump _pPoor, drainage pump flow D _pBy calculating, calculate drainage pump output power W based on drainage pump flow measuring method in the low adding system of fired power generating unit of energy balance _OutExpression:

Described drainage pump flow D _pAdopt following method to obtain:

Step 1-1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain the low inlet water temperature t that adds _WinAnd pressure p _Win, the industrial water and steam thermal properties model IAPWS-IF97 (Association for theProperties of Water and Steam) according to the international water and steam character in 1997 of classics association proposes calculates inlet water enthalpy h _WinObtain the extraction temperature t of heater ₁, extraction pressure p ₁,, calculate the enthalpy h that draws gas of heaters at different levels according to the IAPWS-IF97 of classics ₁Obtain the low outlet coolant-temperature gage t that adds _W1, pressure p _W1,, calculate heater outlet water enthalpy h ' according to the IAPWS-IF97 of classics _W1Obtain the heater condensate temperature t _D1,,, calculate heater condensate enthalpy h at different levels according to the IAPWS-IF97 of classics in conjunction with extraction pressure _D1, hydrophobic flow shares d _D1Expression;

Step 1-2: establish in the low drainage pump that adds hydrophobicly and low to add the mixed flow shares of saliva be 1, hang down that to add the inlet water flow shares be d _In, the 1st grade of hydrophobic flow shares is d _p, according to flow equilibrium relation, d _p=d _D1, heater outlet water enthalpy is h ' _W1, drainage pump outlet enthalpy is h _D1, the enthalpy behind the mixing point is h _W1

Step 1-3: set up the flow equilibrium equation:

d _in+d _p＝1 (1)

Set up mixing point heat Balance Calculation equation:

d _in*h’ _w1+d _p*h _d1＝1*h _w1 (2)

Set up heater heat transfer equation of equilibrium:

d _in*(h’ _w1-h _win)＝d ₁*(h ₁-h _d1) (3)

Because d _p=d ₁, in conjunction with (1), substitution (3) obtains:

d _in*(h’ _w1-h _win)＝(1-d _in)*(h ₁-h _d1) (4)

Further arrangement obtains:

d _in*(h’ _w1-h _win+h ₁-h _d1)＝h ₁-h _d1 (5)

Can obtain d by (5) _InFormula as follows:

d _in＝(h ₁-h _d1)/(h’ _w1-h _win+h ₁-h _d1) (6)

It is as follows to obtain hydrophobic flow shares by (1) and (6):

$d_p=\frac{{\mathrm{\τ}}_1}{{\mathrm{\τ}}_1+q_1}---\left(7\right)$

Wherein, τ ₁=h ' _W1-h _Win, q ₁=h ₁-h _D1,

According to resulting drainage pump flow shares d _p, in conjunction with the water flow checkout value D with fixed attention among SIS or the DCS _n, utilize formula (8) can calculate drainage pump outlet water flow D _p:

D _p＝d _p*D _n (8)

Step 2: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain drainage pump configuration motor real-time current I real-time voltage U, and read drainage pump configuration electric efficiency η and power factor from drainage pump configuration motor nameplate

Calculate drainage pump input power W _In:

Step 3: calculate the drainage pump efficiency eta _p:

With reference to Fig. 4, be example with the 1000MW unit, realize based on separate heater drainage pump outlet water flow measuring and calculating in the energy balance fired power generating unit heat regenerative system.The 1st grade of this 1000MW unit is low to add as separate heater, does not have other hydrophobicly to enter heat release, and heater condensate is by drainage pump pressurization and the mixing of heater outlet water.

1. from the SIS real-time data base, read relevant real time data, data are as follows under certain operating conditions constantly: obtaining band drainage pump heater outlet water pressure is 1.385Mpa, the temperature of obtaining the inlet water of drainage pump is 63.5 ℃, IAPWS-IF97 standard water steam parameter formula according to classics, the inlet water pressure that calculates drainage pump is 0.023378Mpa, and hydrophobic average specific volume is 0.001019m ³/ kg.

The detailed step of 1-1 drainage pump outlet water flow measuring and calculating is as follows:

1. read relevant real time data from the SIS real-time data base, data are as follows under certain operating conditions constantly:

The heater parameter of drawing gas is 0.0235Mpa, 63.6 ℃;

The calorifier inlets parameter is 1.557Mpa, 35.7 ℃;

The heater outlet parameter is 1.385Mpa, 60.7 ℃;

The heater condensate parameter is: 63.5 ℃;

According to the IAPWS-IF97 standard water steam parameter formula of classics, calculate corresponding enthalpy and be:

h ₁(enthalpy draws gas) is: 2493.2kJ/kg; H ' _W1For: 255.2kJ/kg; h _D1(heater condensate enthalpy) is: 540.8kJ/kg;

h _Win(the low inlet water enthalpy that adds) is: 151.1kJ/kg;

D _nBe 596.91t/h.

2. utilize drainage pump flow measuring model, the parameter according in 1. calculates, and is 1 o'clock with respect to oxygen-eliminating device inlet flow rate share, and drainage pump outlet water flow share is 0.0446; Condensing water flow is measured as 596.91t/h, so drainage pump outlet water flow is: 26.64t/h.

2, calculating the drainage pump output power is

Utilize drainage pump flow measuring model, #1 is the surface-type low-pressure heater with a drainage pump.Utilize drainage pump flow measuring model, the parameter according in 1 calculates, and the drainage pump output power is: 10.26kw

3, calculating the drainage pump input power is:

From the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain drainage pump configuration motor real-time current I real-time current U, and to read drainage pump configuration motor electric efficiency η from drainage pump configuration motor nameplate be 0.98 and power factor

Be 0.85, utilize F (P) measuring and calculating model, #1 is the surface-type low-pressure heater with a drainage pump.Reading relevant real time data from the SIS real-time data base, to calculate drainage pump configuration motor real-time current be 8.87A, and drainage pump configuration motor real-time voltage is 1002v, and the drainage pump input power is: 12.83kw.

4, calculating drainage pump efficient is:

Utilize drainage pump flow measuring model, #1 is the surface-type low-pressure heater with a drainage pump.Drainage pump efficient is: 80%.

Claims (1)

1. method for measuring and calculating pump efficiency based on independent low-pressure heater and drainage pump flow soft measurement was made up of independently low adding with a drainage pump, do not have other hydrophobic enter to hang down add.Wherein, utilize drainage pump that low plus hydrophobic is mixed with the low feedwater that adds outlet, it is characterized in that,

Step 1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain band drainage pump heater outlet water pressure p _wObtain the temperature t of the inlet water of drainage pump _p, calculate the inlet water pressure p of drainage pump _pAnd hydrophobic average specific volume

, calculate drainage pump pressure differential deltap p and be band drainage pump heater outlet water pressure p _wInlet water pressure p with drainage pump _pPoor, drainage pump flow D _pBy calculating, calculate drainage pump output power W based on drainage pump flow measuring method in the low adding system of fired power generating unit of energy balance _OutExpression:

Described drainage pump flow D _pAdopt following method to obtain:

Step 1-1: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain the low inlet water temperature t that adds _WinAnd pressure p _Win, calculate inlet water enthalpy h _WinObtain the extraction temperature t of heater ₁, extraction pressure p ₁, calculate the enthalpy h that draws gas of heaters at different levels ₁Obtain the low outlet coolant-temperature gage t that adds _W1, pressure p _W1, calculate heater outlet water enthalpy h ' _W1Obtain the heater condensate temperature t _D1,, calculate heater condensate enthalpy h at different levels in conjunction with extraction pressure _D1, hydrophobic flow shares d _D1Expression;

Step 1-2: establish in the low drainage pump that adds hydrophobicly and low to add the mixed flow shares of saliva be 1, hang down that to add the inlet water flow shares be d _In, the 1st grade of hydrophobic flow shares is d _p, according to flow equilibrium relation, d _p=d _D1, heater outlet water enthalpy is h ' _W1, drainage pump outlet enthalpy is h _D1, the enthalpy behind the mixing point is h _W1

Step 1-3: set up the flow equilibrium equation:

d _in+d _p＝1

Set up mixing point heat Balance Calculation equation:

d _in*h′ _w1+d _p*h _d1＝1*h _w1

Set up heater heat transfer equation of equilibrium:

d _in*(h′ _w1-h _win)＝d ₁*(h ₁-h _d1)

And obtain the flow shares d of drainage pump thus _p:

$d_p=\frac{{\mathrm{\τ}}_1}{{\mathrm{\τ}}_1+q_1}$

Wherein, τ ₁=h ' _W1-h _Win, q ₁=h ₁-h _D1,

Step 1-4: according to the resulting hydrophobic flow shares d of step 3 _p, in conjunction with the water flow D with fixed attention among SIS or the DCS _nCheckout value calculates drainage pump flow D _p, D _p=d _p* D _n

Step 2: from the database of plant level supervisory information system SIS of thermal power plant or decentralized control system DCS, obtain drainage pump configuration motor real-time current I real-time voltage U, and read drainage pump configuration electric efficiency η and power factor from drainage pump configuration motor nameplate

Calculate drainage pump input power W _In:

Step 3: calculate the drainage pump efficiency eta _p:

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