CN1092333C

CN1092333C - Gap mechanism for eliminating wall sticking phenomenon of pipeline-type turbidity sensor

Info

Publication number: CN1092333C
Application number: CN00111783A
Authority: CN
Inventors: 杨汝清
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2000-03-02
Filing date: 2000-03-02
Publication date: 2002-10-09
Anticipated expiration: 2020-03-02
Also published as: CN1264037A

Abstract

The present invention mainly comprises a light source, a sampling tube, a light receiver and a notch. A pair of notches is made in the diameter of the end parts of the sampling tube. The optical path of the light source passes through the notches in the sampling tube and is received by the light receiver.

Description

Eliminate the gap mechanism of duct type turbidity sensor wall cling phenomenon

What the present invention relates to is a kind of gap mechanism of eliminating duct type turbidity sensor wall cling phenomenon.Belong to the sensor field in the physics class.

The turbidity of liquid is meant the degree that contains other impurity in the liquid, because directly miscellaneous impurity is relatively more difficult in the measurement liquid, so all adopting optical principle at present in the world measures indirectly, and the method for testing and the test specification of turbidity have been formed with this, from test philosophy, the tube wall of this pipeline should be transparent, should be transparent at least on light path.The turbidity measurement has the sampling type of interruption to measure and continuous on-line is measured.These two kinds of measurements all have a common problem, and promptly the impurity in the liquid makes the transparent decline of tube wall along with the growth of time can more and more stick on the transparent measurement tube wall, measure inaccurate even can't measure and cause.In the practice, such phenomenon is referred to as wall built-up.Because wall cling phenomenon can influence the operate as normal of sensor, particularly shows even more seriously when on-line continuous is measured, " wall built-up " problem that therefore solves in the measuring process has just become one of key issue of duct type turbidity detection.Through retrieval, find mainly to take on the present engineering following two kinds of methods to reduce and avoid the influence of wall cling phenomenon to prior art.

1, often demarcates and adjust sensor again, make it keep necessary accuracy.In case wall built-up seriously to a certain degree, is demarcated again or is adjusted in the time of can not solving, and can only clean or change again sensor to tube wall.

2, adopt special design, often clean tube wall.Such as, the piston that motor drives is housed in the sampling pipe, utilize piston inspiration fluid to be measured, and piston handle in evening liquid is cleaned tube wall when discharging in passing.See for details: Harry Norton.Sensor and Analyzer Handbook prentice Hall lnc.1982.

In fact first method does not solve the wall built-up problem, just tackles use.If this method is a trouble and bothersome to sampling type, be worthless so basically concerning the on-line continuous formula.

Second method often will be keeped in repair owing to its complex structure, cost height, and actual Use Limitation fruit is not good.

The objective of the invention is to overcome deficiency of the prior art, propose a kind of gap mechanism of eliminating duct type turbidity sensor wall cling phenomenon.

Technical scheme of the present invention is as follows: through the analysis to duct type turbidity sensor wall cling phenomenon, when test, key is fundamentally to eliminate the existence of tube wall, could thoroughly eliminate wall cling phenomenon.The present invention mainly comprises light source, sampling pipe, optical receiver and gap, opens a pair of gap on the diameter of the end of sampling pipe, and the gap of the light path of light source on sampling pipe received by optical receiver.The relative caliber size of size is smaller, so fluid is still more stable through herein the time, and sensor can reach quite high precision.Fluid often will pass through valve, elbow, corner homenergic loss part before entering sampling pipe, make laminar flow shape fluid also can become unstable, in general, when the ratio of sampling pipe length and caliber greater than 5 the time, fluid state can be unaffected.When the ratio of sampling pipe pipe range with caliber is greater than, sensor is work well.In order to obtain stable output signal, the ratio of gap width b and sample tube inner diameter should be approximately equal to 0.2, and the ratio of length a and sample tube inner diameter should be between 1-2.Under the fixing situation of other parameter, be in laminar condition in order to make tube fluid, must the control flow velocity, the flow velocity when Reynolds coefficients R e＜2000 just can the breakable layer stream mode, Re of the present invention＜1000.

The present invention has tangible substantive distinguishing features and marked improvement, owing to eliminated the tube wall phenomenon on the light path of measuring, sensor is moved stably in a long term.

Further describe below with reference to accompanying drawing:

Fig. 1 structural representation of the present invention

Fig. 2 structural representation side view of the present invention

As shown in Figure 1 and Figure 2, the present invention mainly comprises light source 1, sampling pipe 2, optical receiver 3 and gap 4, opens a pair of gap 4 on the diameter of the end of sampling pipe 2, and the gap 4 of the light path of light source 1 on sampling pipe 2 received by optical receiver 3.The relative caliber size of size is smaller, so fluid is still more stable through herein the time, and sensor can reach quite high precision.Fluid often will pass through valve, elbow, corner homenergic loss part before entering sampling pipe 2, make laminar flow shape fluid also can become unstable, in general, when the ratio of sampling pipe 2 length and caliber greater than 5 the time, fluid state can be unaffected.When the ratio of sampling pipe 2 pipe ranges and caliber is greater than 10, sensor is work well.In order to obtain stable output signal, the ratio of gap 4 width b and sampling pipe 2 internal diameters should be approximately equal to 0.2, and the ratio of length a and sampling pipe 2 internal diameters should be between 1-2.Under the fixing situation of other parameter, be in laminar condition in order to make tube fluid, must the control flow velocity, the flow velocity when Reynolds coefficients R e＜2000 just can the breakable layer stream mode, Re of the present invention＜1000.

Lift an example: when the gap size is got a=5mm, b=1mm, with skim milk as the impurity in the liquid (water), when milk concn in the water less than 15% the time, the result who records conforms to Beer ' s Law theoretical curve fully, so concentration big 15%, measured value is less than theoretical value, get between the flow velocity V=0.1m/sec-0.25m/sec, flow velocity changes in this scope not influence of working sensor, has moved week more than two continuously, and the sensor signal that records fluctuates less than 12%, and the common turbidity sensor under similarity condition, its output signal has descended 8.5% in two weeks.

Claims

1, a kind of gap mechanism of eliminating duct type turbidity sensor wall cling phenomenon, mainly comprise light source (1), sampling pipe (2), optical receiver (3), it is characterized in that also comprising gap (4), on the end diameter of sampling pipe (2), open a pair of gap (4), the gap (4) of the light path of light source (1) on sampling pipe (2), receive by optical receiver (3), sampling pipe (2) pipe range is greater than 10 with the ratio of caliber, the ratio of gap (4) width b and sampling pipe (2) internal diameter should be approximately equal to 0.2, and the ratio of length a and sampling pipe (2) internal diameter should be between 1-2.