CN104332193B - A kind of steam generator water level measuring method based on digitizing technique - Google Patents

Abstract

The invention belongs to a kind of nuclear power plant reactor coolant loop process measurement method, be specifically related to a kind of steam generator water level measuring method based on digitizing technique.It comprises the steps: step one: obtain basic parameter；Step 2: obtain basic measurement data；Step 3: water level calculates.Its advantage is, after using digitizing technique, the thermal expansion of the water in the steam generator decline passway under different measuring operating mode, steam, the density of reference Guan Shui and steam generator body can be calculated in real time, make measurement system may insure that under any operating mode and can directly measure actual water level, improve the precision of measurement, alleviate operations staff's burden.

Description

A kind of steam generator water level measuring method based on digitizing technique

Technical field

The invention belongs to a kind of nuclear power plant reactor coolant loop process measurement method, be specifically related to a kind of based on numeral The steam generator water level measuring method of change technology.

Background technology

In nuclear power plant, the water level of steam generator preferably must be held in suitable height, too high or too low all can jeopardize core The safe operation of power plant, it is necessary to being adjusted to proper height in time, otherwise must trigger reactor emergency shut-down, therefore, steam is sent out The water level of raw device is important protection, control and post accident monitoring parameter, improves its certainty of measurement peace to ensureing nuclear power plant Row for the national games is the most necessary.

The level measuring of steam generator generally uses differential pressure method, is i.e. measured between upper and lower pressure tappings by differential pressure transmitter Differential pressure, the actual water level that then signal processing system is calculated in steam generator according to differential pressure.Measure system schematic As shown in Figure 1.

Owing to traditional nuclear power plant's I&C system uses analogue technique, therefore, it is necessary to steam generator water level measurement model Simplify, i.e. select a certain standard condition to demarcate, timing signal, correspondence water level lower limit when allowing transmitter export 4mA, defeated Correspondence water level upper limit when going out 20mA.And for other operating modes, designer's calculated off line go out water level corresponding relation and revise system Number, operations staff determines actual water level according to these correction factors, as shown in Figure 2.

Although using calculated off line can meet operation needs to a certain extent, but due to its low precision, low-response, run Personnel bear weight, and the safety and economic operation of power plant is existed adverse effect.

Along with the extensive application of digitizing technique, the most domestic second phase nuclear power plant of ridge Australia just have employed the instrument of total digitalization Control platform, complicated signal processing method implements and becomes feasible, and increasingly easier, therefore, whether from improving electricity Factory's safety perspective is also an up Human Engineering level angle, calculates the steam generator water level employed in traditional core power plant Method improves the most necessary.

Summary of the invention

It is an object of the invention to provide a kind of steam generator water level measuring method based on digitizing technique, it can carry Rise the accuracy that under various operating modes, steam generator water level is measured, thus improve safety and the economy of nuclear power plant, optimize people Machine interface, alleviates operations staff's burden.

The present invention is achieved in that a kind of steam generator water level measuring method based on digitizing technique, and it includes Following steps:

Step one: obtain basic parameter；

Step 2: obtain basic measurement data；

Step 3: water level calculates.

Described step one includes, by in-site measurement acquisition following parameters:

1) 20 DEG C time upper and lower pressure pipe distance d_p；

2) 20 DEG C time equalizing reservoir to distance d of lower pressure pipe_r；

Wherein, the coefficient of expansion C of steam generator is provided by manufacturer, and gravity acceleration g is surveyed by power plant factory site Arrive, be accurate to after arithmetic point 2.

Described step 2 includes,

1) differential pressure of water level Δ P is obtained by water level transmitter,

2) acquisition main steam mass flow Q is measured by main steam system_V, specific enthalpy E_V, pressure P_S,

3) acquisition feed-water quality flow Q is measured by main feed system_FWith specific enthalpy E_F, E_RFor returning flow ratio enthalpy.

Described step 3 comprises the steps,

1) circulating ratio R is calculated

$R=\frac{Q_F-Q_V}{Q_V}$

2) specific enthalpy E of decline passway water is calculated_D

$E_D=\frac{(R-1)E_R+E_F}{R}$

3) temperature T of decline passway water is calculated_DAnd density p_D

The computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97, according to decline passway water Specific enthalpy E_DWith pressure P_SCalculate temperature T of decline passway water_DAnd density p_D,

4) calculate with reference to water density ρ_r

The computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97, according to pressure P_SAnd instrument Temperature T of table pipe_rThe density p of water in calculating gauge pipe_rIf gauge pipe does not has temperature survey, T generally can be taken_r=40 DEG C,

5) density p of steam is calculated_v

Steam in steam generator is in saturated mode, by water and steam thermodynamic properties international standard IAPWS- The computational methods that IF97 provides, according to steam pressure P_SCalculate the density p of steam_v,

6) calculated equilibrium container is to distance D of lower pressure pipe_r

D_r=d_r+C(T_D-20)d_p

7) steam generator actual water level is calculated

$H=\frac{\frac{\mathrm{\ΔP}}{g}-D_r({\mathrm{\ρ}}_V-{\mathrm{\ρ}}_r)}{{\mathrm{\ρ}}_D-{\mathrm{\ρ}}_V}.$

It is an advantage of the invention that after using digitizing technique, can be under the steam generator under different measuring operating mode The thermal expansion of water, steam, the density of reference Guan Shui and steam generator body in fall passage calculates in real time, makes survey Amount system may insure that can directly measure actual water level under any operating mode, improves the precision of measurement, alleviates fortune Administrative staff bears.

Accompanying drawing explanation

Fig. 1 is for measuring system schematic；

Fig. 2 is water level corresponding relation and correction factor schematic diagram；

Fig. 3 is that steam generator measures water level and actual water level corresponding relation transmitter calibration maps at full power.

In figure, 1 steam generator, 2 equalizing reservoirs, pressure pipe on 3,4 times pressure pipes, 5 differential pressure transmitters.

Detailed description of the invention

With example, the present invention is described in detail below in conjunction with the accompanying drawings:

The technical problem to be solved in the present invention is convenient by make full use of that digitizing technique brings on signal processing, will Affect during each physical parameter that steam generator water level measures brings measurement system-computed into, thus realize accurately measuring The purpose of steam generator actual water level.

A kind of steam generator water level measuring method based on digitizing technique, including:

Step one: obtain basic parameter

After measurement system installs, by in-site measurement acquisition following parameters:

1) 20 DEG C time upper and lower pressure pipe distance d_p；

2) 20 DEG C time equalizing reservoir to distance d of lower pressure pipe_r

Wherein, the coefficient of expansion C of steam generator is provided by manufacturer, and gravity acceleration g is surveyed by power plant factory site Arrive, be accurate to after arithmetic point 2.

Step 2: obtain basic measurement data

1) differential pressure of water level Δ P is obtained by water level transmitter

2) acquisition main steam mass flow Q is measured by main steam system_V, specific enthalpy E_V, pressure P_S

3) acquisition feed-water quality flow Q is measured by main feed system_FWith specific enthalpy E_F, E_RFor returning flow ratio enthalpy,

Step 3: water level calculates

Water-level gauge point counting is following several step:

1) circulating ratio R is calculated

$R=\frac{Q_F-Q_V}{Q_V}$

2) specific enthalpy E of decline passway water is calculated_D

$E_D=\frac{(R-1)E_R+E_F}{R}$

3) temperature T of decline passway water is calculated_DAnd density p_D

(other are approved closely for the computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97 Can also use like fitting formula), according to specific enthalpy E of decline passway water_DWith pressure P_SCalculate temperature T of decline passway water_DWith close Degree ρ_D。

4) calculate with reference to water density ρ_r

(other are approved closely for the computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97 Can also use like fitting formula), according to pressure P_STemperature T with gauge pipe_rThe density p of water in calculating gauge pipe_r.If instrument Table pipe does not has temperature survey, generally can take T_r=40℃。

5) density p of steam is calculated_v

Steam in steam generator is in saturated mode, by water and steam thermodynamic properties international standard IAPWS- The computational methods (other approved approximate fits formula can also use) that IF97 provides, according to steam pressure P_SCalculate steam Density p_v。

6) calculated equilibrium container is to distance D of lower pressure pipe_r

D_r=d_r+C(T_D-20)d_p

7) steam generator actual water level is calculated

$H=\frac{\frac{\mathrm{\ΔP}}{g}-D_r({\mathrm{\ρ}}_V-{\mathrm{\ρ}}_r)}{{\mathrm{\ρ}}_D-{\mathrm{\ρ}}_V}$

Wherein,

d_p, D_pThe distance of pressure pipe up and down

(d_p: when 20 DEG C；D_p: under operating condition)

d_r, D_rEqualizing reservoir is to the distance of lower pressure pipe

(d_r: when 20 DEG C；D_r: under operating condition)

The coefficient of expansion of C steam generator

ρ_DThe density of water in decline passway

ρ_vThe density of steam

ρ_rThe density of water in gauge pipe

T_DThe temperature of decline passway water

T_rThe temperature of gauge pipe

Q_F,E_FFeed-water quality flow and specific enthalpy

Q_R,E_RReturn current mass flow and specific enthalpy

Q_D,E_DDecline passway mass flow and specific enthalpy

Q_V,E_VSteam mass flow and specific enthalpy

R circulating ratio

During Δ P water level differential pressure transmitter measurement to differential pressure value (high-pressure side (H.P.) subtracts low-pressure side (L.P.))

Actual water level in H steam generator

P_SMain steam pressure

Then have:

ΔP=[H(ρ_D-ρ_V)+D_r(ρ_V-ρ_r)]g。

Claims (1)

1. a steam generator water level measuring method based on digitizing technique, it is characterised in that: it comprises the steps:

Step one: obtain basic parameter；

Step 2: obtain basic measurement data；

Step 3: water level calculates；

Described step one includes, by in-site measurement acquisition following parameters:

1) 20 DEG C time upper and lower pressure pipe distance d_p；

2) 20 DEG C time equalizing reservoir to distance d of lower pressure pipe_r；

Wherein, the coefficient of expansion C of steam generator is provided by manufacturer, and gravity acceleration g is obtained by power plant's factory site actual measurement, essence Really to after arithmetic point 2；

Described step 2 includes,

1) differential pressure of water level Δ P is obtained by water level transmitter,

2) acquisition main steam mass flow Q is measured by main steam system_V, specific enthalpy E_V, pressure P_S,

3) acquisition feed-water quality flow Q is measured by main feed system_FWith specific enthalpy E_F, E_RFor returning flow ratio enthalpy；

Described step 3 comprises the steps,

1) circulating ratio R is calculated

$R=\frac{Q_F-Q_V}{Q_V}$

2) specific enthalpy E of decline passway water is calculated_D

$E_D=\frac{(R-1)E_R+E_F}{R}$

3) temperature T of decline passway water is calculated_DAnd density p_D

The computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97, according to the ratio of decline passway water Enthalpy E_DWith pressure P_SCalculate temperature T of decline passway water_DAnd density p_D,

4) calculate with reference to water density ρ_r

The computational methods provided by water and steam thermodynamic properties international standard IAPWS-IF97, according to pressure P_SAnd gauge pipe Temperature T_rThe density p of water in calculating gauge pipe_rIf gauge pipe does not has temperature survey, T generally can be taken_r=40 DEG C,

5) density p of steam is calculated_v

Steam in steam generator is in saturated mode, is carried by water and steam thermodynamic properties international standard IAPWS-IF97 The computational methods of confession, according to steam pressure P_SCalculate the density p of steam_v,

6) calculated equilibrium container is to distance D of lower pressure pipe_r

D_r=d_r+C(T_D-20)d_p

7) steam generator actual water level is calculated

$H=\frac{\frac{\mathrm{\Δ}P}{g}-D_r({\mathrm{\ρ}}_V-{\mathrm{\ρ}}_r)}{{\mathrm{\ρ}}_D-{\mathrm{\ρ}}_V}.$