CN103871520A - Major loop flow quantity accurate measurement method based on digitization technology - Google Patents

Abstract

The invention belongs to a nuclear power plant reactor coolant system process measurement method, and particularly relates to a major loop flow quantity accurate measurement method based on a digitization technology. The major loop flow quantity accurate measurement method based on the digitization technology comprises the following steps: (1) acquiring a flow quantity coefficient C and a main pipeline circulation cross-sectional area S; (2) acquiring measuring data; (3) calculating the density [rho]L of a coolant; (4) calculating the flow velocity v of the coolant according to an equation shown in the description; and (5) calculating the flow quantity of the coolant. The method has the advantages: after adopting the digitization technology, the density of the coolant flowing through an elbow under different measurement working conditions can be real-timely calculated, so that the measurement system can ensure that the actual major loop flow quantity can be directly measured under any working condition, the measurement precision is improved, and the burden of operating personnel is alleviated.

Description

A kind of major loop flow accurate measurement 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 major loop flow accurate measurement method based on digitizing technique.

Background technology

In pressurized-water reactor nuclear power plant; reactor coolant loop major loop flow is important procedure parameter; if flow is too low; the ability that cooling medium is taken away reactor core heat will reduce; crisis is to the safety of reactor core, therefore, and when flow just need to trigger shutdown when setting limit value; meanwhile, reactor coolant loop major loop flow is also important operational factor.Therefore, measuring as far as possible exactly reactor coolant loop major loop flow is the important development direction that improves power plant safety and economy.

Conventionally, for simplified measurement system, reactor coolant loop major loop Flow Measuring System utilizes the pressure of reactor coolant loop major loop elbow, as shown in Figure 1:

When fluid is when the elbow, owing to being subject to the constraint of elbow, fluid is similar to circular motion, and the centrifugal action of generation is in the both sides of elbow, thereby makes the inside and outside both sides of elbow produce a pressure reduction.This pressure extent is relevant with shape, the flow velocity of fluid and the density of fluid of elbow, conventionally can be expressed as:

$v=C\sqrt{\frac{\mathrm{\ΔP}}{\mathrm{\ρ}}}$

Wherein C is coefficient of flow, and v is flow velocity, and ρ is fluid density, and Δ P is the differential pressure between outside in elbow.

Because the traditional I & C of nuclear power plant system adopts analogue technique, be difficult to calculate in real time the density of water, therefore, power plant is conventionally under Hot zero power level, the rated flow that all main pumps are all normally put into operation is demarcated as 100%, under other operating modes, coolant density is approximate thinks constant, directly uses differential pressure calculated flow rate, does not consider the variation of density.Owing to lacking density compensation, the actual flow of measuring system under cannot Measurement accuracy unusual service condition, security and economy to power plant have adverse effect.

Along with the widespread use of digitizing technique, such as domestic second phase nuclear power plant of ridge Australia has just adopted totally digitilized instrument control platform, complicated signal processing method implements and becomes feasible, and more and more easier, therefore, no matter be from improving power plant safety angle or promote Human Engineering level angle, the major loop method of flow adopting being improved all very necessary in traditional core power plant.

Summary of the invention

The object of this invention is to provide a kind of major loop flow accurate measurement method based on digitizing technique, it,, by adopting digitizing technique, calculates coolant density under different operating modes, promotes the accuracy of major loop flow measurement under various operating modes.

The present invention is achieved in that a kind of major loop flow accurate measurement method based on digitizing technique, and it comprises the steps,

(1) obtain flow coefficient C and main pipeline actual internal area S;

(2) obtain measurement data;

(3) calculate coolant density ρ L;

(4) calculate coolant flow speed v;

$v=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}$

(5) calculate coolant flow.

Described step (1), for after nuclear power plant's major loop elbow has been produced, can be carried out Experimental Calibration by producer and obtain flow coefficient C, also can, during power station commissioning, obtain flow coefficient C by debugging, provides actual internal area S by main pipeline manufacturer.

Described step (2) is outside differential pressure Δ P in the differential pressure transmitter measurement elbow by being arranged on elbow; Flow through the coolant temperature T of elbow by being arranged on thermometer measure on loop; By being arranged on the narrow range pressure transmitter measurement major loop pressure P g of voltage stabilizer; Measure the absolute pressure Pc in containment by the absolute pressure gauge that is arranged in containment.

Described step (3) is

1) the absolute pressure P of calculating cooling medium _a=P _g+ P _c

2) calculate following coefficient:

H ₁=-38.39+0.492P _a

H ₂=4.043-3.027×10 ^-3P _a

H ₃=-11427.6+1545.2P _a

H ₄=-26351+1239.1P _a

D ₁=999.55+0.497P _a

D ₂=-2.585×10 ^-4+6.175×10 ^-7P _a

D ₃=1.27×10 ^-10-4.92×10 ^-13P _a

D ₄=1488.5+1.338P _a

D ₅=1.4695×10 ⁶+8854.9P _a

D ₆=3203.72+12.045P _a

3) the specific enthalpy H of calculating cooling medium _l(kJ/kg):

H _L=H ₁+H ₂T+H ₃(428-T) ^-1+H ₄(T-399) ^-1

4) calculate coolant density

When:

-H _L>650?ρ _L=D ₄+D ₅(H _L-D ₆) ^-1

-H _L≤650?ρ _L=D ₁+D ₂H _L ²+D ₃H _L ⁴

Described step (4) is for calculating coolant flow speed v;

$v=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}.$

Described step (5) is calculating coolant flow,

Volume: $Q_V=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}\·S$

Mass rate: $Q_M=C\·\sqrt{{\mathrm{\ρ}}_L\·\mathrm{\ΔP}}\·S.$

Advantage of the present invention is, adopting after digitizing technique, can calculate in real time the coolant density that flows through elbow under different measuring operating mode, make measuring system can guarantee can directly measure actual major loop flow under any operating mode, improve the precision of measuring, alleviated operations staff's burden.

Brief description of the drawings

Fig. 1 is reactor coolant loop major loop elbow pressure schematic diagram.

In figure, 1LP pressure side, 2HP pressure side.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail:

The technical problem to be solved in the present invention be by make full use of digitizing technique bring signal process on convenient, each physical parameter that affects major loop flow measurement is brought in measuring system computation process, thereby realized the object of accurately measuring major loop actual flow.

In order to solve the problems of the technologies described above, the invention provides a kind of major loop flow accurate measurement method based on digitizing technique, comprising:

Step 1: obtain flow coefficient C and main pipeline actual internal area S

After nuclear power plant's major loop elbow has been produced, can carry out Experimental Calibration by producer and obtain flow coefficient C, also can, during power station commissioning, obtain flow coefficient C by debugging.

Provide actual internal area S by main pipeline manufacturer.

Step 2: obtain measurement data

Measure differential pressure Δ P in outside in elbow by being arranged on the differential pressure transmitter of elbow; Flow through the coolant temperature T of elbow by being arranged on thermometer measure on loop; By being arranged on the narrow range pressure transmitter measurement major loop pressure P of voltage stabilizer _g; Measure the absolute pressure P in containment by the absolute pressure gauge that is arranged in containment _c.

Step 3: calculate coolant density ρ _l

1) the absolute pressure P of calculating cooling medium _a=P _g+ P _c

2) calculate following coefficient:

H ₁=-38.39+0.492P _a

H ₂=4.043-3.027×10 ^-3P _a

H ₃=-11427.6+1545.2P _a

H ₄=-26351+1239.1P _a

D ₁=999.55+0.497P _a

D ₂=-2.585×10 ^-4+6.175×10 ^-7P _a

D ₃=1.27×10 ^-10-4.92×10 ^-13P _a

D ₄=1488.5+1.338P _a

D ₅=1.4695×10 ⁶+8854.9P _a

D ₆=3203.72+12.045P _a

3) the specific enthalpy H of calculating cooling medium _l(kJ/kg):

H _L=H ₁+H ₂T+H ₃(428-T) ^-1+H ₄(T-399) ^-1

4) calculate coolant density

When:

-H _L>650?ρ _L=D ₄+D ₅(H _L-D ₆) ^-1

-H _L≤650?ρ _L=D ₁+D ₂H _L ²+D ₃H _L ⁴

Note: above-mentioned is fitting formula for calculating the formula of coolant density, also can in actual use

To use other approved density calculation formula.

Step 4: calculate coolant flow speed v

$v=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}$

Step 5: calculate coolant flow

Volume: $Q_V=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}\·S$

Mass rate: $Q_M=C\·\sqrt{{\mathrm{\ρ}}_L\·\mathrm{\ΔP}}\·S$

Claims (6)

1. the major loop flow accurate measurement method based on digitizing technique, is characterized in that: it comprises the steps,

(1) obtain flow coefficient C and main pipeline actual internal area S;

(2) obtain measurement data;

(3) calculate coolant density ρ _l;

(4) calculate coolant flow speed v;

$v=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}$

(5) calculate coolant flow.

2. the major loop flow accurate measurement method based on digitizing technique, it is characterized in that: described step (1) is for after nuclear power plant's major loop elbow has been produced, can carry out Experimental Calibration by producer and obtain flow coefficient C, also can be during power station commissioning, obtain flow coefficient C by debugging, provide actual internal area S by main pipeline manufacturer.

3. the major loop flow accurate measurement method based on digitizing technique, is characterized in that: described step (2) is outside differential pressure Δ P in the differential pressure transmitter measurement elbow by being arranged on elbow; Flow through the coolant temperature T of elbow by being arranged on thermometer measure on loop; By being arranged on the narrow range pressure transmitter measurement major loop pressure P g of voltage stabilizer; Measure the absolute pressure Pc in containment by the absolute pressure gauge that is arranged in containment.

4. the major loop flow accurate measurement method based on digitizing technique, is characterized in that: described step (3) is

1) the absolute pressure P of calculating cooling medium _a=P _g+ P _c

2) calculate following coefficient:

H ₁=-38.39+0.492P _a

H ₂=4.043-3.027×10 ^-3P _a

H ₃=-11427.6+1545.2P _a

H ₄=-26351+1239.1P _a

D ₁=999.55+0.497P _a

D ₂=-2.585×10 ^-4+6.175×10 ^-7P _a

D ₃=1.27×10 ^-10-4.92×10 ^-13P _a

D ₄=1488.5+1.338P _a

D ₅=1.4695×10 ⁶+8854.9P _a

D ₆=3203.72+12.045P _a

3) the specific enthalpy H of calculating cooling medium _l(kJ/kg):

H _L=H ₁+H ₂T+H ₃(428-T) ^-1+H ₄(T-399) ^-1

4) calculate coolant density

When:

-H _L>650?ρ _L=D ₄+D ₅(H _L-D ₆) ^-1

-H _L?≤650?ρ _L=D ₁+D ₂H _L ²+D ₃H _L ⁴

5. the major loop flow accurate measurement method based on digitizing technique, is characterized in that: described step (4) is for calculating coolant flow speed v;

$v=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}.$

6. the major loop flow accurate measurement method based on digitizing technique, is characterized in that: described step (5) is calculating coolant flow,

Volume: $Q_V=C\·\sqrt{\frac{\mathrm{\ΔP}}{{\mathrm{\ρ}}_L}}\·S$

Mass rate: $Q_M=C\·\sqrt{{\mathrm{\ρ}}_L\·\mathrm{\ΔP}}\·S.$