CN103699141B - LNG tank thermal imaging is thermal imaging system adjustment and localization method for monitoring - Google Patents

Abstract

The invention discloses LNG tank thermal imaging monitoring thermal imaging system adjustment and localization method, it comprises the following steps: (1) determines the mounting distance of thermal infrared imager according to the angle of visual field of thermal infrared imager; (2) according to the setting height(from bottom) of site requirements setting thermal infrared imager; (3) at storage tank mid-height place, a heat point source is set, opens thermal infrared imager, make thermal infrared imager take thermal map center and overlap with the heat point source setting; (4) thermal map of thermal infrared imager being taken the vertically upper height boundary point on axis and the coordinate transform of lower height boundary point is the height coordinate on storage tank outer wall; (5) keep the inclination angle of thermal infrared imager constant, by thermal infrared imager vertically mobile preset distance make thermal infrared imager can once photograph storage tank short transverse image. Employing this method can detect whole height of Large LNG storage tank, finds in time the change of temperature field of storage tank outer wall.

Description

LNG tank thermal imaging is thermal imaging system adjustment and localization method for monitoring

Technical field

The present invention relates to a kind of thermal infrared imager positioner, the thermal imaging system attitude that relates in particular to the monitoring of LNG storage tank is adjustedWhole and localization method.

Background technology

Liquefied natural gas (LNG) storage tank is liquefied natural gas transport and the requisite air container of storage, in recent yearsThe development of LNG storage tank is to large capacity future development. LNG storage tank is the steel inner canister by splendid attire low temperature LNG liquidWith the compound facility that provides the concrete outer tank of normal operating environment and defencive function to form. Once steel inner canister partAppearance is broken, and heat-insulation layer lost efficacy, storage tank outer wall concrete destruction, all can cause tank temperature field to change, and makes storage tank sideWall local temperature reduces, and jeopardizes storage tank safety. Thermal infrared imager can demonstrate body surface temperature in thermal map modeCome, be applicable to industry monitoring. Because Large LNG flask volume is huge, utilize thermal infrared imager to carry out overall height to itThe temperature monitoring of degree need to be adjusted the installation location of instrument, and installation site need to repeatedly be pacified mostly at presentDress, constantly adjusts modification summary and obtains.

Summary of the invention

The object of the invention is to overcome the shortcoming of prior art, provide the one can be to all height sidewall temperature of storage tankDegree is monitored, and increases work efficiency, and finds that in time the LNG tank thermal imaging monitoring of dangerous matter sources is with hotPicture instrument adjustment and localization method.

LNG tank thermal imaging of the present invention is thermal imaging system adjustment and localization method for monitoring, and it comprises following stepRapid:

(1) determine the mounting distance of thermal infrared imager according to the angle of visual field of thermal infrared imager, the calculating public affairs of mounting distanceFormula is:

$\begin{array}{cc}{L}_{\min }=\frac{\frac{H}{2}}{\tan \frac{\mathrm{\α}}{2}}& L\≥L_{\min }\end{array}$

In formula, L is the horizontal range of thermal infrared imager installation site and storage tank outer wall, and α is looking of thermal infrared imagerRink corner, H is the height of storage tank;

(2) according to the setting height(from bottom) of site requirements setting thermal infrared imager, get 3-4 rice;

(3) at storage tank mid-height place, a heat point source is set, opens thermal infrared imager, make thermal infrared imager take heatFigure center overlaps with the heat point source setting, and the mounted angle θ of thermal imaging system is:In formulaθ is the mounted angle of thermal imaging system, the setting height(from bottom) that h is thermal infrared imager;

(4) thermal map of thermal infrared imager being taken is upper height boundary point and the lower height limit on axis verticallyThe coordinate of boundary's point is transformed to respectively the imaginary plane height coordinate on the imaginary plane in thermal imaging system shooting process, then by voidThe storage tank height that plane coordinate transformation can photograph to determine thermal infrared imager for the height coordinate on storage tank outer wallScope;

(5) keep the inclination angle of thermal infrared imager constant, by thermal infrared imager vertically mobile preset distance make infraredThermal imaging system can once photograph storage tank short transverse image.

Adopt this method by adjusting installation site and the attitude of thermal infrared imager, it can be detected large-scaleWhole height of LNG storage tank, find the change of temperature field of storage tank outer wall in time, simple to operation, can be greatlySave the installation positioning time of thermal infrared imager, increase work efficiency, determine in time dangerous matter sources.

Brief description of the drawings

Fig. 1 is thermal map coordinate system schematic diagram.

Fig. 2 is perspective view, and wherein 1 is thermal infrared imager, 2 thermal imaging system optical axis, and the 3rd, storage tank outer wall, the 4th,Imaginary plane S, the 5th, heat point source.

Detailed description of the invention

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

LNG tank thermal imaging of the present invention thermal imaging system adjustment and localization method for monitoring as shown in drawings, its bagDraw together following steps:

(1) determine the mounting distance of thermal infrared imager according to the angle of visual field of thermal infrared imager 1, the calculating of mounting distanceFormula is:

$\begin{array}{cc}{L}_{\min }=\frac{\frac{H}{2}}{\tan \frac{\mathrm{\α}}{2}}& L\≥L_{\min }\end{array}$

In formula, L is the horizontal range of thermal infrared imager installation site and storage tank outer wall 3, and α is thermal infrared imagerThe angle of visual field, H is the height of storage tank;

(2) according to the setting height(from bottom) h of site requirements setting thermal infrared imager, get 3-4 rice;

(3) at storage tank mid-height place, a heat point source 5 is set, opens thermal infrared imager, thermal infrared imager is takenThermal map center overlaps with the heat point source setting, and the mounted angle θ of thermal imaging system is:In formulaθ is the mounted angle of thermal imaging system, the setting height(from bottom) that h is thermal infrared imager;

(4) thermal map of thermal infrared imager being taken is upper height boundary point and the lower height limit on axis verticallyThe coordinate of boundary's point is transformed to respectively the imaginary plane height coordinate on the imaginary plane in thermal imaging system shooting process, then by voidThe storage tank height that plane coordinate transformation can photograph to determine thermal infrared imager for the height coordinate on storage tank outer wallScope;

(5) keep the inclination angle of thermal infrared imager constant, by thermal infrared imager vertically mobile preset distance make infraredThermal imaging system can once photograph storage tank short transverse image.

Moving preset distance as one embodiment of the present invention can determine according to following formula, formula:

$\mathrm{\Δh}=\frac{y_{A2}+y_{B2}}{2}$

In formula Δ h be thermal infrared imager adjustment vertically move down distance; y_A2、y_B2Respectively that thermal infrared imager is clappedUpper height boundary point and the lower height boundary point taken the photograph in the thermal map obtaining on axis are vertically corresponding to storage tankCoordinate in outer wall coordinate system, storage tank outer wall coordinate system be heat point source taking storage tank half At The Height as the origin of coordinates,Level is to the right x axle positive direction, is the rectangular coordinate system that y axle positive direction is set up straight up.

Certainly coordinate transform formula can also adopt additive method.

In described step (4), the coordinate of upper height boundary point and lower height boundary point is transformed to respectively at thermal imaging systemThe method of the imaginary plane height coordinate on the imaginary plane in shooting process can be:

Set up rectangular coordinate system at thermal map center, horizontal direction is to the right x axle positive direction, and vertical direction is upwards yAxle positive direction. The height border of getting respectively on thermal map on the y axle vertical direction that can photograph is respectively A₀、B₀。Suppose to exist and pass through storage tankThe heat point source of At The Height, and be parallel to the imaginary plane S of thermal imaging system, as shown in Figure 2.On imaginary plane S4, set up rectangular coordinate system taking heat point source as the origin of coordinates, taking horizontal direction to the right as x axle prosTo, by heat point source and be upwards y axle positive direction perpendicular to x direction of principal axis. A₀、B₀Correspond to upper point of imaginary plane SNot not A₁、B₁。A₁、B₁Height coordinate definite according to following formula:

If the position coordinates of certain point on thermal map is (x₀,y₀), its position coordinates that corresponds on imaginary plane S is(x₁,y₁), according to the corresponding relation of optical imagery:

$\frac{F}{f}=\frac{y_1}{y_0}$

In formula, F is the distance of thermal imaging system upper heat point source along thermal imaging system optical axis to empty face S;

F is the focal length of thermal imaging system.

Can obtain successively the some A on thermal map according to above-mentioned formula₀、B₀Correspond to the upper A of imaginary plane S₁、B₁PositionPut coordinate.

The method that in described step (4) by imaginary plane coordinate transform is the storage tank height coordinate on storage tank outer wall is:

On storage tank outer wall, set up rectangular coordinate system taking heat point source as the origin of coordinates, taking horizontal direction to the right as x axle justDirection, vertical direction is upwards y axle positive direction, the A on imaginary plane S₁、B₁Point corresponds on storage tank outer wall minuteWei A₂、B₂。

A₂、B₂Height coordinate definite according to following formula:

$y_{A2}=L\tan (\arctan \frac{y_{A1}}{F}+\mathrm{\θ})+h-\frac{H}{2}$

$y_{B2}=L\tan (\arctan \frac{y_{B1}}{F}-\mathrm{\θ})+h-\frac{H}{2}$

Can obtain successively the some A on thermal map according to above-mentioned formula₁、B₁Correspond to A on storage tank outer wall₂、B₂HeightCoordinate y_A2、y_B2。

In order to make thermal imaging system can photograph whole height of storage tank, must adjust thermal imaging system position. Keep heatThe inclination angle of picture instrument is constant, and it is vertically upper mobile. If thermal map point A₀、B₀Correspond to the height on storage tank outer wallCoordinate is respectively y_A2、y_B2, mobile height distance Δ h is positive moving direction straight down, mobile height distance rootDetermine according to following formula:

${\mathrm{\Δ}}_1=y_{A2}-\frac{H}{2}$

${\mathrm{\Δ}}_2=y_{B2}+\frac{H}{2}$

$\mathrm{\Δh}={\mathrm{\Δ}}_2+\frac{{\mathrm{\Δ}}_1-{\mathrm{\Δ}}_2}{2}=\frac{y_{A2}+y_{B2}}{2}$

In formula, Δ₁、Δ₂Respectively the thermal infrared imager visual field height that can photograph and actual tank roof height, storage tankDistance between end height; Δ h is that thermal infrared imager is adjusted the distance on the vertical direction of the required movement in position, vertically toIt is down positive moving direction.

By above-mentioned formula, can calculate thermal infrared imager along needing mobile distance, delta h in short transverse.

Claims (1)

1. LNG tank thermal imaging is monitored with thermal imaging system adjustment and localization method, it is characterized in that it comprisesFollowing steps:

(1) determine the mounting distance of thermal infrared imager according to the angle of visual field of thermal infrared imager, the calculating of mounting distanceFormula is:

$\begin{array}{cc}{L}_{min}=\frac{\frac{H}{2}}{\tan \frac{\mathrm{\α}}{2}}& L\≥L_{min}\end{array}$

In formula, L is the horizontal range of thermal infrared imager installation site and storage tank outer wall, and α is thermal infrared imagerThe angle of visual field, H is the height of storage tank;

(2) according to the setting height(from bottom) of site requirements setting thermal infrared imager, get 3-4 rice;

(3) at storage tank mid-height place, a heat point source is set, opens thermal infrared imager, thermal infrared imager is takenThermal map center overlaps with the heat point source setting, and the mounted angle θ of thermal imaging system is:The mounted angle that in formula, θ is thermal imaging system, the setting height(from bottom) that h is thermal infrared imager;

(4) thermal map of thermal infrared imager being taken is upper height boundary point and the lower height on axis verticallyThe coordinate of boundary point is transformed to respectively the imaginary plane height coordinate on the imaginary plane in thermal imaging system shooting process, thenBy imaginary plane coordinate transform for the height coordinate on storage tank outer wall is to determine what thermal infrared imager can photographStorage tank altitude range;

(5) keep the inclination angle of thermal infrared imager constant, by thermal infrared imager vertically mobile preset distance makeThermal infrared imager can once photograph storage tank short transverse image;

Mobile preset distance is determined according to following formula:

$\mathrm{\Δ}h=\frac{y_{A2}+y_{B2}}{2}$

In formula Δ h be thermal infrared imager adjustment vertically move down distance; y_A2、y_B2It is respectively thermal infrared imager instituteIn the thermal map that shooting obtains vertically the upper height boundary point on axis and lower height boundary point in correspondenceTo the coordinate in storage tank outer wall coordinate system, storage tank outer wall coordinate system is that heat point source taking storage tank half At The Height is as seatMark initial point, level is to the right x axle positive direction, is the rectangular coordinate system that y axle positive direction is set up straight up.