A kind of liquid metal pressure measuring method and device
Technical field
The present invention relates to a kind of high temperature fluent metal device for pressure measurement.
The invention still further relates to a kind of method utilizing said apparatus to measure high temperature fluent metal pressure.
Background technology
Liquid metal is owing to having high exchange capability of heat, have a wide range of applications at the industrial circle of high heat flux radiating requirements, especially be widely used at present in nuclear industry field, the metal as lead bismuth alloy, Li-Pb alloy, sodium and Na-K alloy etc. with higher boiling low melting point is applied as primary Ioops heat eliminating medium at present in some reactors.Because the characteristic such as flowing heat transfer of liquid metal is different from Common fluids, extensive liquid metal flows heat transfer and Study on Corrosion Characteristics experiment porch in the laboratory of domestic and international many research institutions, are also built.Liquid metal generally has corrosivity, and temperature is higher, and the measurement of its key parameter pressure is one of them difficult point, and pressure monitor is a required index of fluent metal loop safe operation.The pressure that generally have employed the mode liquid towards metal of two groups of membrane sensors is at present measured, pressure transducer does not directly contact the liquid metal with higher corrosive power and higher temperature, the diaphragm of independent making high-temperature corrosion resistance is with liquid metal contacts, then little and measure for liquid metal pressure is delivered to pressure transducer by liquid medium under normal temperature by filling corrosivity between this diaphragm and pressure transducer diaphragm in one segment pipe, reduce temperature by the natural convection cooling of intermediate conduit simultaneously, pressure transducer is operated in safe temperature range.The pressure measurement device configurations of two groups of diaphragms is complicated, require higher to middle filled media, perfect condition be can not piezodielectric and volume not best by influence of temperature change, otherwise because the change of temperature can cause larger measuring error, its boiling point wants high, with the higher temperature of liquid metal contacts side under can not produce phase transformation, also to keep liquid under normal temperature, have less corrosivity, therefore the selection of secondary side medium is also a difficult point, is difficult to find desirable intermediate medium.If after the diaphragm directly contacted with liquid metal damages, online replacing can not be realized.Major part liquid metal, therefore can not contact diaphragm again under liquid metal air-setting condition at normal temperatures generally in solid-state, otherwise volume change in process of setting may produce irreversible damage to direct contact diaphragm.
Summary of the invention
The object of this invention is to provide a kind of liquid metal pressure measurement mechanism.
Another object of the present invention is to provide a kind of method utilizing said apparatus to measure liquid metal pressure.
For achieving the above object, a kind of liquid metal pressure measurement mechanism provided by the invention, mainly comprises:
One tensimeter connects flue;
Flue connects impulse separator tube by switching elbow;
Impulse separator tube is connected to liquid metal pipeline by elbow.
Described liquid metal pressure measurement mechanism, wherein, is connected with valve between tensimeter and flue.
Described liquid metal pressure measurement mechanism, wherein, impulse separator tube can arbitrarily angledly be connected with liquid metal pipeline.
Described liquid metal pressure measurement mechanism, wherein, the tube wall of impulse separator tube is provided with temperature sensor, electrical heating elements and insulation material; Temperature sensor, electrical heating elements are connected with PID control instrument, relay respectively, and PID control instrument is connected with relay.
Described liquid metal pressure measurement mechanism, wherein, impulse separator tube is provided with temperature sensor near one end of flue.
The method utilizing said apparatus to measure liquid metal pressure provided by the invention:
First liquid metal pressure measurement mechanism inside is vacuumized, be filled with the protection of inert gas pressure-fired, when liquid metal flows through liquid metal pipeline, discharged by gas in elbow and be filled with liquid metal, the inert gas in impulse separator tube and flue is closed in pipe;
When liquid metal manifold pressure raises, compress the inert gas be enclosed in impulse separator tube and flue, until reach pressure equilibrium, the pressure of correspondence position liquid metal can be obtained by gauge measurement gaseous tension.
Described method, wherein, the inert gas be filled with is argon gas or nitrogen.
Described method, wherein, flue is vertically to place and in an atmosphere exposed; Impulse separator tube is that level is laid.
Described method, wherein, comparing calculation is carried out with set temperature in the temperature acquisition that temperature sensor measurement obtains to PID control instrument, the heating power controlling electrical heating elements maintains the fusing point of impulse separator tube minimum temperature higher than liquid metal, prevent liquid metal from solidifying in pipe, affect pressure survey.
The present invention has the following advantages:
1) structure is simple, does not need two groups of diaphragm co-operation;
2) do not need to fill middle liquid medium;
3) replacing sensor element can be safeguarded by direct-on-line;
4) liquid metal solidification also can not have damage to sensor;
5) when there is pipeline plugging fault, liquid towards stress metal has buffer action.
Accompanying drawing explanation
Device schematic diagram when Fig. 1 is liquid metal pipeline of the present invention with impulse separator tube in vertical connection.
Fig. 2 is liquid metal pipeline of the present invention and impulse separator tube device schematic diagram when horizontally connecting.
Primary clustering symbol description in accompanying drawing:
1 tensimeter; 2 tensimeter mount pads; 3 valves; 4 flues; 5 switching elbows; 6 insulation materials; 7 electrical heating elements; 8 impulse separator tubes; 9,10 elbows; 11 relays; 12PID control instrument; 13 temperature sensors; 14 liquid metal pipelines.
Embodiment
Pressure tester of the present invention includes tensimeter 1 (can be pointer, digital display manometer etc.), tensimeter mount pad 2, valve 3 (can be ball valve, stop valve etc.), flue 4, switching elbow 5, insulation material 6, electrical heating elements 7 (can be heat tape, electric heating film, electric heating sheets etc.), impulse separator tube 8, elbow 9 and 10, relay 11 (can be A.C. contactor, solid-state relay, pressure regulator etc.), PID control instrument 12, temperature sensor 13 (can be thermopair, thermal resistance etc.).Concrete annexation is as shown in Figure 1:
Tensimeter 1 is arranged on tensimeter mount pad 2, and is connected to flue 4, is provided with valve 3 between tensimeter 1 and flue 4.Flue 4 is connected to one end of impulse separator tube 8 by switching elbow 5.Impulse separator tube can arbitrarily angledly be connected with liquid metal pipeline, due to Fig. 1 display be liquid metal pipeline 14 with impulse separator tube 8 is vertical annexation, therefore between impulse separator tube 8 and liquid metal pipeline 14, adopt two elbows 9,10, namely the other end of impulse separator tube 8 is connected to liquid metal pipeline 14 by elbow 9,10.The relation if liquid metal pipeline 14 and impulse separator tube 8 horizontally connect, then only need installation elbow 9 as shown in Figure 2.The tube wall of impulse separator tube 8 is provided with temperature sensor 13, electrical heating elements 7, insulation material 6, temperature sensor 13 is connected with PID control instrument 12, and electrical heating elements 7 is connected with relay 11, and relay 11 is connected with PID control instrument 12.
When said apparatus of the present invention uses, before performance loop filling liquid metal, first process is vacuumized to said apparatus, hunt leak simultaneously, ensure the gas tightness of tensimeter 1 of the present invention, flue 4 and impulse separator tube 8.By being filled with the protection of inert gas pressure-fired after vacuumizing process, prevent foreign gas in air from infiltrating, inert gas generally adopts the large molecular gas such as argon gas or nitrogen.When liquid metal flows through liquid metal pipeline 14, owing to there is density difference, the gas in elbow 10 is discharged, and is filled with liquid metal, and the inert gas in elbow 9 and impulse separator tube 8, flue 4 is closed in pipe.When the pressure in liquid metal pipeline 14 raises, compression is enclosed in the inert gas in elbow 9 and impulse separator tube 8, flue 4, until reach pressure equilibrium, now gaseous tension that tensimeter is surveyed is liquid metal pipeline correspondence position pressure after revising.After revising, the pressure at liquid metal pipeline 14 impulse mouth place can be expressed as:
P=P
0+ρ
lgH
In formula, P
0for tensimeter 1 measuring pressure, ρ
1for liquid metal density, g is acceleration of gravity, and H is the vertical distance between liquid metal pipeline 14 impulse position and impulse separator tube 8 central shaft.
In the present invention impulse separator tube 8 and flue 4 internal capacity and flue 4 length and wall thickness choose more crucial, the maximum pressure that may occur when need put normal work according to institute's location designs.The maximum pressure putting appearance according to institute's location calculates and is enclosed in gas in pipe by the volume after compressing, the volume of flue 4 will be slightly smaller than the volume under maximum pressure after gas compression, volume compression section is partially absorbed by the impulse separator tube 8 of larger volume, and under maximum pressure, in impulse separator tube 8, liquid metal fullness rate is more than 90%.In order to trouble free service; flue 4 needs vertical placement, in an atmosphere exposed, and length and thickness should meet before when slowly revealing appears in closed gas, liquid metal inflow gas pipe 4 arrives valve 3; by naturally cooling the requirement that can make liquid metal solidification, to protect manometer safety.Meet by after naturally cooling simultaneously, normally to work the maximum temperature allowed lower than tensimeter 1 with tensimeter 1 contact portion gas temperature in any case.
In the present invention, impulse separator tube 8 wants horizontal positioned, and the packed height reduced as far as possible due to interior liquid metal changes the pressure measurement errors caused.The outer wall of impulse separator tube 8 is provided with temperature sensor 13 near flue 4 one end, measuring tempeature collects in PID control instrument 12 and carries out contrast computing with the control objectives value of setting, pilot relay 11 action, regulate the heating power of the electrical heating elements 7 of impulse separator tube 8 outer wall, maintain the fusing point of impulse separator tube 8 minimum temperature higher than liquid metal, prevent liquid metal from solidifying in pipe, affect pressure survey.
In the present invention, tensimeter 1 is changed in the effect of valve 3 online, and when tensimeter 1 breaks down, valve-off 3 can be changed online to tensimeter 1, and then by valve closing, open valve after setting pressure table 1, apparatus of the present invention can normally work.
In the present invention, liquid metal directly contacts with gas, and when there is the faults such as line clogging, buffer action is played in the sharply change of liquid towards stress metal.In flue 4, inert gas has compressibility, and therefore the present invention is not suitable for pressure and changes violent transient pressure measurement, is suitable for the pressure survey of steady flow and the pressure survey of slowly change.
The present invention can directly adopt the pressure of conventional pressure sensor liquid towards metal to measure, and structure is simple, is easy to safeguard, even if also can not cause damage to pressure transducer after liquid metal solidification.Thus the two groups of membrane sensors overcome in known technology and device, do not need two groups of membrane combination to use, there is not liquid intermediate medium select permeability.