CN105136987A - Detection apparatus and detection method for formaldehyde concentration in laboratory - Google Patents

Abstract

The present invention discloses a detection apparatus and a detection method for the formaldehyde concentration in a laboratory. The detection apparatus comprises a controller, a memory, a bottom plate, a gas chamber arranged on the bottom plate and having a rectangular cross-section, a tail gas treatment device arranged on the bottom plate, a support frame arranged on the bottom plate, a guide structure arranged on the support frame, and a transverse screw rod arranged on the support frame, wherein the top portion of the inner wall of the gas chamber is provided with a plurality of fans for blasting downward, and the inner side wall of the gas chamber wall is sequentially provided with at least two layers of gas sensitive films, a metal mesh for supporting the gas sensitive films and formed by electric heating wires, and a horizontal separation plate positioned on the lower portion of the metal mesh and used for separating the gas chamber into an upper part and a lower part from top to bottom. The apparatus of the present invention has advantages of high sensitivity, good stability, short response time and good formaldehyde selectivity, and can detect the trace formaldehyde gas with the low concentration so as to effectively protect people health.

Description

Concentration of formaldehyde pick-up unit and detection method in laboratory

Technical field

The present invention relates to Environmental security technical field, especially relate to a kind of can fast, concentration of formaldehyde pick-up unit and detection method in the laboratory of accurate testing laboratory's Formaldehyde in Environment concentration.

Background technology

Formaldehyde, for having comparatively high toxicity, is in second in Chinese toxic chemical priority acccess control list, and being defined as carcinogenic and cause deformed material by the World Health Organization (WHO), is generally acknowledged allergen, is also one of potential strong mutagen.

The impact of formaldehyde poisoning on health is mainly manifested in the aspects such as allotriosmia, stimulation, allergy, abnormal pulmonary function, dysfunction of liver and immunologic dysfunction.Other common symptom comprises uncomfortable in chest, feels sick, skin, fash, asthma etc.

At present low concentration formaldehyde detection method is mainly relied on to the method for instrumental analysis, as vapor-phase chromatography etc.Although above-mentioned detection method can the concentration of trace formaldehyde in testing environment accurately, but the deficiencies such as ubiquity sense cycle length, cost intensive, and the those of skill in the art's operating instrument equipment needing through professional training, the scene of trace formaldehyde in environment that cannot realize accurately is detected fast.

Therefore, the detection system for trace formaldehyde used at present exists that sensitivity is low, poor selectivity, poor stability or can not topic between Long-Time Service.

Chinese patent Authorization Notice No.: CN101846610A, authorized announcement date on September 29th, 2010, disclose a kind of gas-detecting device and gas detecting system, it comprises quartz plate, first electrode, second electrode and adsorbed layer, described quartz plate has relative first surface and second surface, described first electrode is formed at first surface, described second electrode is formed at second surface, described adsorbed layer is formed at the first electrode surface, described adsorbed layer is made up of iridium-iridium dioxide nanometer rods, for adsorbing gas to be detected, change to make the quality of gas-detecting device, thus obtain the concentration of gas to be detected.It is slow to there is detection speed in this invention, the deficiency that accuracy of detection is low.

Summary of the invention

The present invention is that the sense cycle in order to overcome gas detection method of the prior art is long, cost is high, the deficiency of apparatus expensive, provide a kind of can fast, concentration of formaldehyde pick-up unit and detection method in the laboratory of accurate testing laboratory's Formaldehyde in Environment concentration.

To achieve these goals, the present invention is by the following technical solutions:

Concentration of formaldehyde pick-up unit in a kind of laboratory, comprises controller, storer, base plate, is located at air chamber, exhaust gas processing device and bracing frame that xsect on base plate is rectangular, is located at the guide frame on bracing frame and cross lead screw;

Described air chamber inwall top is provided with for several fans to canyon, air chamber madial wall be from top to bottom provided with successively at least 2 layers of gas sensitization film, for support gas sensitization film the wire netting be made up of heating wire, be positioned at wire netting bottom and air chamber be divided into upper and lower two-part horizontal baffle, air chamber inner bottom part is provided with supporting plate, detection head and the track along splint upper surface Spiral distribution, and detection head is provided with MQ-2 sensor, MQ-135 sensor and formaldehyde sensor; Gas sensitization film is provided with several through holes, and the air chamber inwall corresponding with gas sensitization film location is provided with some air guide vertical slots;

Cross lead screw one end is connected with the rotating shaft of the first motor be located on bracing frame, described air chamber is provided with the opening for inserting horizontal baffle, horizontal baffle outer end is provided with web joint, detection head bottom is provided with the second motor for driving detection head orbital motion, web joint is connected with wire rod thread, web joint and guide frame are slidably connected, and are positioned at the draft tube on the air chamber of horizontal baffle upper and lower and escape pipe; Draft tube and escape pipe are equipped with solenoid valve; Hermetically-sealed construction is provided with between opening and horizontal baffle;

Also comprise the vertical screw mandrel between being located at bottom supporting plate and air chamber, vertical screw mandrel top and supporting plate threaded engagement, vertical screw mandrel bottom is connected with air chamber by the bearing be located at bottom air chamber, and screw mandrel lower end is connected with the rotating shaft of the 3rd motor be located in air chamber bottom;

Hermetically-sealed construction is provided with between opening and horizontal baffle; Exhaust gas processing device is connected with the escape pipe on air chamber top;

Controller is electrically connected with storer, each electric fan, each solenoid valve, wire netting, the first motor, the second motor, the 3rd motor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor respectively.

Gas sensitization film is used for adsorption experiment room gas, and gas sensitization film has gas inrichment, can by gas sensitization film successively ultrasonic cleaning 15min in HNO3 (1: 1), acetone and distilled water, and the electrode after cleaning dries for subsequent use under being placed in room temperature; Mixed with polyglycol solution by cider by a certain percentage, evenly obtain potpourri with sonic oscillation, drawing 5 μ L massfractions with micro syringe is the potpourri of 5%Nafion, drips and is applied to gas sensitization film surface, dry stand-by under room temperature.

Wire netting is used for heated air sensitive membrane, and each fan is used for the gas come out from gas sensitization film through overbaking to blow to air chamber bottom, is convenient to each sensor and detects; Horizontal baffle is used for partitioned air chambers upper and lower, thus facilitates air chamber upper and lower to carry out gas enrichment and sensor cleaning simultaneously; Bracing frame, guide frame, cross lead screw and the first motor move horizontally for driving horizontal baffle, thus make controller will be divided into upper and lower two parts by the first Electric Machine Control horizontal baffle in air chamber or make air chamber recover as a whole; Supporting plate provides support to track, and track provides the guiding moving to supporting plate different parts to detection head, and MQ-2 sensor and MQ-135 sensor are respectively used to testing environment signal, and formaldehyde sensor is for detecting formaldehyde gas signal; Second motor is for driving detection head along rail moving, and the 3rd motor is elevated for driving pallet.

Because sensor all has cross sensitivity to detected object gas, therefore the present invention adopts MQ-2 sensor and MQ-135 sensor as aiding sensors, formaldehyde sensor is as the master reference detecting formaldehyde gas, the signal that MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect is merged, obtain sensor fusion signal signal (t), thus both remained the Detection Information of master reference, remain again the signal difference information between master reference and aiding sensors, improve accuracy of detection.

Therefore, the present invention there is highly sensitive, good stability and the response time short, PARA FORMALDEHYDE PRILLS(91,95) has good selectivity, can detect the trace formaldehyde gas that concentration is lower, thus effectively ensures the feature that people are healthy.

As preferably, also comprise and be located at temperature sensor on detection head and humidity sensor; Temperature sensor and humidity sensor are all electrically connected with controller.Temperature sensor and humidity sensor are respectively used to detected temperatures and humidity, thus make the correction of sensor fully remove the impact of environmental factor, and it is more accurate, reliable to correct.

As preferably, described track comprises substrate, is located at two spaced grooves of upper surface of base plate, and described groove floor is provided with the tooth bar arranged at equal intervals; Be provided with bottom described detection head two with the gear of fit depressions; The rotating shaft of described second motor is connected with the coupling shaft be located between two gears;

Described substrate is provided with the first baffle plate, the second baffle relative with the first baffle plate; First baffle plate, second baffle are provided with corresponding guide chute; The coupling shaft two ends of described gear are provided with the outrigger shaft of guide chute for inserting the first baffle plate, second baffle; Detection head lower surface is provided with several balls with the first baffle plate, second baffle upper surface Structure deformation.The setting of guide chute, outrigger shaft and ball, make the stability of detection head better, friction force is less.

As preferably, support frame as described above comprises the U-shaped frame that Open Side Down, is located at the L shape frame of air chamber front and rear; Described guide frame is be located at two crossbeams between U-shaped frame and two L shape framves; Described web joint is rectangular, and web joint bottom is provided with for 2 through holes through two crossbeams, and web joint top is provided with the screw hole for coordinating with cross lead screw.

As preferably, in gas sensitization film, be provided with the cavity that several are spaced apart, in cavity, be provided with the carbon nano-tube of stretching out outside gas sensitization film upper and lower surface; Exhaust gas processing device is spirit lamp.Cavity and carbon nano-tube add the adsorptive power of gas sensitization film to gas.

In laboratory, a detection method for concentration of formaldehyde pick-up unit, comprises the steps:

(6-1) controller controls the first driven by motor cross lead screw and rotates, and cross lead screw drives horizontal baffle to move horizontally outside air chamber by web joint, and when horizontal baffle the inner being moved to contact with opening position, controller controls the first motor and quits work;

(6-2) solenoid valve that controller controls on draft tube and escape pipe was all opened, and is filled with nitrogen by draft tube in air chamber, to MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes;

(6-3) laboratory air to be detected is filled with by draft tube to air chamber Inner eycle, the laboratory air that exhaust gas processing device process exports from escape pipe; The adsorbed gas of gas sensitization film, after 5 to 15 minutes, controller controls the closed electromagnetic valve on draft tube and escape pipe;

(6-4) controller controls wire netting energising, controls each electric fan work simultaneously, and the gas of gas sensitization film absorption enters air chamber bottom, and after 5 to 8 minutes, controller controls wire netting power-off, and each electric fan quits work;

(6-5) controller controls the first driven by motor cross lead screw rotation, cross lead screw drives horizontal baffle to move horizontally in air chamber by web joint, when horizontal baffle outer end being moved to contact with opening position to contact, controller controls the first motor and quits work;

(6-6) controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of formaldehyde sensor, detection signal S2 (t) of MQ-2 sensor, detection signal S3 (t) of MQ-135 sensor; Controller utilizes formula signal (t)=S1 ²(t)+(S1 (t)-S2 (t)) ²+ (S1 (t)-S3 (t)) ²calculating sensor merges signal signal (t);

(6-7) be previously stored with accidental resonance model and concentration of formaldehyde forecast model in storer, inputted by signal (t) in accidental resonance model, controller calculates the output signal-to-noise ratio SNR during resonance of accidental resonance model,

SNR is inputted in concentration of formaldehyde forecast model, obtain the concentration of formaldehyde of the laboratory air be detected.

Because sensor all has cross sensitivity to detected object gas, therefore the present invention adopts MQ-2 sensor and MQ-135 sensor as aiding sensors, formaldehyde sensor is as the master reference detecting formaldehyde gas, detection signal S1 (t) of MQ-2 sensor, detection signal S2 (t) of MQ-135 sensor, detection signal S3 (t) of formaldehyde sensor, the present invention utilizes formula

Signal (t)=S1 ²(t)+(S1 (t)-S2 (t)) ²+ (S1 (t)-S3 (t)) ²the signal that MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect is merged, obtain sensor fusion signal signal (t), thus both remained the Detection Information of master reference, remain again the signal difference information between master reference and aiding sensors, improve accuracy of detection.

As preferably, described also comprising is located at temperature sensor on detection head and humidity sensor; Temperature sensor and humidity sensor are all electrically connected with controller; It is characterized in that, described step (6-2) is replaced by following step:

(7-1) solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber bottom, nitrogen is filled with, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes by draft tube;

(7-2) in air chamber, be filled with by draft tube the laboratory air that known concentration of formaldehyde is S, the laboratory air that exhaust gas processing device process exports from escape pipe; Ventilate after 3 to 10 minutes, the solenoid valve that controller controls on draft tube and escape pipe all cuts out;

Controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of formaldehyde sensor, detection signal S2 (t) of MQ-2 sensor, detection signal S3 (t) of MQ-135 sensor;

(7-3) n the sample value S11 be spacedly distributed of S1 (t) chosen by controller, S12 ..., S1n, choose n the sample value S21 be spacedly distributed of S2 (t), S22 ..., S2n, choose n the sample value S31 be spacedly distributed of S3 (t), S32 ..., S3n;

Utilize formula

Di ²=(S1i-S) ²+ (S2i-S) ²+ (S3i-S) ², i=1,2 ..., n, calculated difference is apart from huge from di ²;

Utilize following formula $A=\left[\begin{array}{c}{(S11-S)}^2\\ {(S12-S)}^2\\ .\\ .\\ .\\ {(S1n-S)}^2\end{array}\right],B=\left[\begin{array}{c}{(S21-S)}^2\\ {(S22-S)}^2\\ .\\ .\\ .\\ {(S2n-S)}^2\end{array}\right],C=\left[\begin{array}{c}{(S31-S)}^2\\ {(S32-S)}^2\\ .\\ .\\ .\\ {(S3n-S)}^2\end{array}\right],$ $D=\left[\begin{array}{c}d{1}^2\\ d{2}^2\\ .\\ .\\ .\\ {\mathrm{dn}}^2\end{array}\right]$ Compute matrix A respectively, B, C and D; Minimum threshold e is provided with, to A, B, C, D, concentration of formaldehyde table that temperature and humidity is relevant in storer;

(7-4) controller inquires about concentration of formaldehyde s ' according to the temperature of A, B, C, D, detection and the humidity of detection by concentration of formaldehyde table,

When data in A have 80%≤e at least and in D data have 80%≤e at least and time, the solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber, be filled with nitrogen by draft tube, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes, proceed to step (6-3); Otherwise, proceed to step (7-1).

Step (7-2) to (7-4) is the trimming process to MQ-2 sensor, MQ-135 sensor and formaldehyde sensor, only have and meet A+B+C=D and in A, data have 82%≤e at least and in D, data have the MQ-2 sensor of the correcting condition of 82%≤e, MQ-135 sensor and formaldehyde sensor at least just for detecting gas to be detected, otherwise need repetition trimming process, thus improve the precision of sensor detection.

As preferably, the computation process of described output signal-to-noise ratio SNR comprises the steps:

The computation process of described output signal-to-noise ratio SNR comprises the steps:

Signal (t) is inputted one deck accidental resonance model

in;

Wherein, V (x, t, α) is potential function, the movement locus that x (t) is Brownian Particles, and t is run duration, and α is particle transient motion acceleration, D ₂for external noise intensity, N (t) grasps noise in being, for periodic sinusoidal signal, A ₁be signal amplitude, f is signal frequency, for phase place; A, b are the constant of setting; If

Controller calculates the first order derivative of V (x, t, α) for x, second derivative and three order derivatives, and makes equation equal 0, obtains two layers of accidental resonance model:

Setting noise intensity D ₂=0, signal (t)=0, N (t)=0; Calculate A ₁critical value be

By A ₁critical value substitute in one deck accidental resonance model, and set X ₀(t)=0, sn ₀=0, with quadravalence jade for asking rain Ge Kuta Algorithm for Solving one deck accidental resonance model, obtain

$x_{m1}\left(t\right)=x_m\left(t\right)+1/6\[{\left(k_1\right)}_m+(2-\sqrt{2}){\left(k_2\right)}_m+(2+\sqrt{2}){\left(k_3\right)}_m+{\left(k_4\right)}_m\],$ M=0,1 ..., N-1; And calculate:

${\left(k_1\right)}_m=4({\mathrm{a\αx}}_{m-1}{\left(t\right)}^2-{\mathrm{b\αx}}_{m-1}{\left(t\right)}^3+{\mathrm{sn}}_{m-1}(t))$

${\left(k_2\right)}_m=4\[a\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_1\right)}_{m-1}}{3})-b{\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_1\right)}_{m-1}}{3})}^3+{\mathrm{sn}}_{m-1}\]$

${\left(k_3\right)}_m=4\[a\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_2\right)}_{m-1}}{3})-b{\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{\sqrt{2}-1}{3}{\left(k_1\right)}_{m-1}+\frac{2-\sqrt{2}}{3}{\left(k_2\right)}_{m-1})}^3+{\mathrm{sn}}_{m+1}\]$

${\left(k_4\right)}_n=4\[a\left(3{\mathrm{\αx}}_{m-1}\right(t)+{\left(k_3\right)}_{m-1})-b{\left({\mathrm{\αx}}_{m-1}\right(t)-\frac{\sqrt{2}}{3}{\left(k_2\right)}_{m-1}+\frac{2+\sqrt{2}}{3}{\left(k_3\right)}_{m-1})}^3+{\mathrm{sn}}_{m+1}\]$

Wherein, x _mt m order derivative that () is x (t), sn _m-1the value of m-1 order derivative at t=0 place of S (t), sn _m+1the m+1 order derivative being S (t), in the value at t=0 place, obtains x ₁(t), x ₂(t) ..., x _m+1the value of (t);

Controller is to x ₁(t), x ₂(t) ..., x _m+1t () carries out integration, obtain x (t), and obtains x (t) produces accidental resonance moment position x in the double-deck stochastic system of one deck accidental resonance model and two layers of accidental resonance model composition ₁value and x ₁corresponding resonance moment t ₁, optimum transient motion acceleration alpha ₁, and and t ₁and α ₁corresponding noise D ₁, D ₁for D ₂in a value;

Controller utilizes formula $SNR=2{\left({\mathrm{\ΔU}}^2\frac{4a^3/27b}{D_1}\right)}^3{e}^{-{\left(\mathrm{\Δ}U\right)}^3/D_1^2}$ Calculate the signal to noise ratio snr that double-deck stochastic resonance system exports; Wherein, △ U=a ²/ 4b.

As preferably, controller calculates and obtains the averaged amplitude value SS of signal (t) in testing process, described A ₁≤ 0.54SS, the 9.8SS≤D in one deck accidental resonance model and two layers of accidental resonance model ₂≤ 19.5SS; A and b all≤SS.

To A ₁, D ₂with the restriction of a and b span, guarantee that one deck accidental resonance model and two layers of accidental resonance model have good sensitivity, thus make the signal to noise ratio snr of output more accurate.

As preferably, concentration of formaldehyde forecast model is concentration of formaldehyde W=2.34+0.37 × SNR.

Therefore, the present invention has following beneficial effect: (1) is highly sensitive, good stability and the response time short, PARA FORMALDEHYDE PRILLS(91,95) has good selectivity, can detect the trace formaldehyde gas that concentration is lower, thus effective ensures that people are healthy; (2) simple to operate, testing cost is low.

Accompanying drawing explanation

Fig. 1 is a kind of theory diagram of the present invention;

Fig. 2 is a kind of cut-open view of air chamber of the present invention;

Fig. 3 is a kind of vertical view of concentration of formaldehyde pick-up unit of the present invention;

Fig. 4 is a kind of structural representation of web joint of the present invention;

Fig. 5 is a kind of cross-sectional structure schematic diagram of track of the present invention;

Fig. 6 is a kind of vertical view of track of the present invention;

Fig. 7 is a kind of process flow diagram of embodiments of the invention.

In figure: controller 1, base plate 2, air chamber 3, bracing frame 4, guide frame 5, cross lead screw 6, fan 7, gas sensitization film 8, wire netting 9, horizontal baffle 10, supporting plate 11, track 12, detection head 13, first motor 14, web joint 15, second motor 16, solenoid valve 17, temperature sensor 18, humidity sensor 19, MQ-2 sensor 20, MQ-135 sensor 21, formaldehyde sensor 22, draft tube 23, escape pipe 24, storer 25, vertical screw mandrel 26, 3rd motor 27, exhaust gas processing device 28, substrate 121, groove 122, gear 123, coupling shaft 124, first baffle plate 125, second baffle 126, guide chute 127, outrigger shaft 128, U-shaped frame 41, L shape frame 42, crossbeam 51, through hole 151, screw hole 152, ball 129.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

Embodiment 1

Embodiment is as shown in Figure 1 and Figure 2 concentration of formaldehyde pick-up unit in a kind of laboratory, comprise controller 1, storer 25, base plate 2, be located at air chamber 3, exhaust gas processing device 28 and bracing frame 4 that xsect on base plate is rectangular, be located at the guide frame 5 on bracing frame and cross lead screw 6;

As shown in Figure 2, air chamber inwall top is provided with for 5 fans 7 to canyon, air chamber madial wall be from top to bottom provided with successively 2 layers of gas sensitization film 8, for support gas sensitization film the wire netting 9 be made up of heating wire, be positioned at wire netting bottom and air chamber be divided into upper and lower two-part horizontal baffle 10, air chamber inner bottom part is provided with supporting plate 11, detection head 13 and the track 12 along splint upper surface Spiral distribution, and detection head is provided with MQ-2 sensor 20, MQ-135 sensor 21 and formaldehyde sensor 22; Gas sensitization film is provided with 5 through holes; The air chamber inwall corresponding with gas sensitization film location is provided with 8 air guide vertical slots;

As shown in Figure 3, cross lead screw one end is connected with the rotating shaft of the first motor 14 be located on bracing frame, air chamber is provided with the opening for inserting horizontal baffle, horizontal baffle outer end is provided with web joint 15, detection head bottom is provided with the second motor 16 for driving detection head orbital motion, web joint is connected with wire rod thread, and web joint and guide frame are slidably connected, and is positioned at the draft tube 23 on the air chamber of horizontal baffle upper and lower and escape pipe 24; Draft tube and escape pipe are equipped with solenoid valve 17; Hermetically-sealed construction is provided with between opening and horizontal baffle;

Also comprise the vertical screw mandrel 26 between being located at bottom supporting plate and air chamber, vertical screw mandrel top and supporting plate threaded engagement, vertical screw mandrel bottom is connected with air chamber by the bearing be located at bottom air chamber, and screw mandrel lower end is connected with the rotating shaft of the 3rd motor 27 be located in air chamber bottom; Exhaust gas processing device is connected with the escape pipe on air chamber top;

As shown in Figure 1, controller is electrically connected with storer, each electric fan, each solenoid valve, wire netting, the first motor, the second motor, the 3rd motor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor respectively.

As shown in Figure 5, Figure 6, track comprises substrate 121, is located at two of upper surface of base plate spaced grooves 122, and groove floor is provided with the tooth bar arranged at equal intervals; Be provided with bottom described detection head two with the gear 123 of fit depressions; The rotating shaft of the second motor is connected with the coupling shaft 124 be located between two gears.

Substrate is provided with the first baffle plate 125, the second baffle 126 relative with the first baffle plate; First baffle plate, second baffle are provided with corresponding guide chute 127; The coupling shaft two ends of gear are provided with the outrigger shaft 128 of guide chute for inserting the first baffle plate, second baffle; Detection head lower surface is provided with the multiple balls 129 with the first baffle plate, second baffle upper surface Structure deformation.

As shown in Figure 3, bracing frame comprises the U-shaped frame 41 that Open Side Down, is located at the L shape frame 42 of air chamber front and rear; Guide frame is be located at two crossbeams 51 between U-shaped frame and two L shape framves; As shown in Figure 4, web joint is rectangular, and web joint bottom is provided with for 2 through holes 151 through two crossbeams, and web joint top is provided with the screw hole 152 for coordinating with cross lead screw.

Be provided with multiple cavity spaced apart in gas sensitization film, in cavity, be provided with the carbon nano-tube of stretching out outside gas sensitization film upper and lower surface.Exhaust gas processing device is spirit lamp.

As shown in Figure 7, in a kind of laboratory, the detection method of concentration of formaldehyde pick-up unit, comprises the steps:

Step 100, takes out boiling water flat partition board

Controller controls the first driven by motor cross lead screw and rotates, and cross lead screw drives horizontal baffle to move horizontally outside air chamber by web joint, and when horizontal baffle the inner being moved to contact with opening position, controller controls the first motor and quits work;

Step 200, sensor cleans

The solenoid valve that controller controls on draft tube and escape pipe was all opened, and is filled with nitrogen by draft tube in air chamber, to MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes;

Step 300, the adsorbed gas of gas sensitization film

Laboratory air to be detected is filled with to air chamber Inner eycle, the laboratory air that exhaust gas processing device process exports from escape pipe by draft tube; The adsorbed gas of gas sensitization film, after 5 to 15 minutes, controller controls the closed electromagnetic valve on draft tube and escape pipe;

Step 400, heated air sensitive membrane, and the gas that gas sensitization film discharges is blowed to air chamber bottom

Controller controls wire netting energising, controls each electric fan work simultaneously, and the gas of gas sensitization film absorption enters air chamber bottom, and after 5 to 8 minutes, controller controls wire netting power-off, and each electric fan quits work;

Step 500, closed horizontal baffle

Controller controls the first driven by motor cross lead screw and rotates, and cross lead screw drives horizontal baffle to move horizontally in air chamber by web joint, and when horizontal baffle outer end being moved to contact with opening position to contact, controller controls the first motor and quits work;

Step 600, each sensor detects gas signal and obtains sensor fusion signal

Controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of MQ-2 sensor, detection signal S2 (t) of MQ-135 sensor, detection signal S3 (t) of formaldehyde sensor; Controller utilizes formula signal (t)=S1 ²(t)+(S1 (t)-S2 (t)) ²+ (S1 (t)-S3 (t)) ²calculating sensor merges signal signal (t);

Step 700, calculates and obtains the concentration of formaldehyde of laboratory air that detects

Be previously stored with accidental resonance model and concentration of formaldehyde forecast model in storer, inputted by signal (t) in accidental resonance model, controller calculates the output signal-to-noise ratio SNR during resonance of accidental resonance model,

SNR is inputted concentration of formaldehyde forecast model: in concentration of formaldehyde W=2.34+0.37 × SNR, obtain the concentration of formaldehyde of the laboratory air be detected.

Concentration of formaldehyde forecast model utilizes step 100 to detect various concentration known to 700 to be respectively W1, W2 ..., the formaldehyde gas of W100, obtains the output signal-to-noise ratio SNR1 corresponding with often kind of concentration of formaldehyde, SNR2 ..., SNR100; Utilize point (W1, SNR1), (W2, SNR2),, (W100, SNR100) does a little in rectangular coordinate system, obtain the formula of the matched curve of each point, the formula of matched curve is converted, obtains concentration of formaldehyde forecast model of the present invention.

The computation process of described output signal-to-noise ratio SNR comprises the steps:

Signal (t) is inputted one deck accidental resonance model

in;

Wherein, V (x, t, α) is potential function, the movement locus that x (t) is Brownian Particles, and t is run duration, and α is particle transient motion acceleration, D ₂for external noise intensity, N (t) grasps noise in being, for periodic sinusoidal signal, A ₁be signal amplitude, f is signal frequency, for phase place; A, b are the constant of setting; If

Wherein, controller calculates and obtains the averaged amplitude value SS of signal (t) in testing process, described A ₁≤ 0.54SS, the 9.8SS≤D in one deck accidental resonance model and two layers of accidental resonance model ₂≤ 19.5SS; A and b all≤SS.

Controller calculates the first order derivative of V (x, t, α) for x, second derivative and three order derivatives, and makes equation equal 0, obtains two layers of accidental resonance model:

Setting noise intensity D ₂=0, signal (t)=0, N (t)=0; Calculate A ₁critical value be

By A ₁critical value substitute in one deck accidental resonance model, and set X ₀(t)=0, sn ₀=0, with quadravalence jade for asking rain Ge Kuta Algorithm for Solving one deck accidental resonance model, obtain

$x_{m1}\left(t\right)=x_m\left(t\right)+1/6\[{\left(k_1\right)}_m+(2-\sqrt{2}){\left(k_2\right)}_m+(2+\sqrt{2}){\left(k_3\right)}_m+{\left(k_4\right)}_m\],$ M=0,1 ..., N-1; And calculate:

${\left(k_1\right)}_m=4({\mathrm{a\αx}}_{m-1}{\left(t\right)}^2-{\mathrm{b\αx}}_{m-1}{\left(t\right)}^3+{\mathrm{sn}}_{m-1}(t))$

${\left(k_2\right)}_m=4\[a\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_1\right)}_{m-1}}{3})-b{\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_1\right)}_{m-1}}{3})}^3+{\mathrm{sn}}_{m-1}\]$

${\left(k_3\right)}_m=4\[a\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{{\left(k_2\right)}_{m-1}}{3})-b{\left({\mathrm{\αx}}_{m-1}\right(t)+\frac{\sqrt{2}-1}{3}{\left(k_1\right)}_{m-1}+\frac{2-\sqrt{2}}{3}{\left(k_2\right)}_{m-1})}^3+{\mathrm{sn}}_{m+1}\]$

${\left(k_4\right)}_n=4\[a\left(3{\mathrm{\αx}}_{m-1}\right(t)+{\left(k_3\right)}_{m-1})-b{\left({\mathrm{\αx}}_{m-1}\right(t)\frac{\sqrt{2}}{3}{\left(k_2\right)}_{m-1}+\frac{2+\sqrt{2}}{3}{\left(k_3\right)}_{m-1})}^3+{\mathrm{sn}}_{m+1}\]$

Wherein, x _mt m order derivative that () is x (t), sn _m-1the value of m-1 order derivative at t=0 place of S (t), sn _m+1the m+1 order derivative being S (t), in the value at t=0 place, obtains x ₁(t), x ₂(t) ..., x _m+1the value of (t);

Controller is to x ₁(t), x ₂(t) ..., x _m+1t () carries out integration, obtain x (t), and obtains x (t) produces accidental resonance moment position x in the double-deck stochastic system of one deck accidental resonance model and two layers of accidental resonance model composition ₁value and x ₁corresponding resonance moment t ₁, optimum transient motion acceleration alpha ₁, and and t ₁and α ₁corresponding noise D ₁, D ₁for D ₂in a value; D ₂with a function of 0.01 loop cycle stepping in [0,1] scope, D ₂value and time correlation, be aware of t ₁moment, D ₁just determine.

Controller utilizes formula $SNR=2{\left({\mathrm{\ΔU}}^2\frac{4a^3/27b}{D_1}\right)}^3{e}^{-{\left(\mathrm{\Δ}U\right)}^3/D_1^2}$ Calculate the signal to noise ratio snr that double-deck stochastic resonance system exports; Wherein, △ U=a ²/ 4b.

Embodiment 2

In embodiment 2, comprise all structures and the step part of embodiment 1, also comprise in embodiment 2 as shown in Figure 1 be located at temperature sensor 18 on detection head and humidity sensor 19; Temperature sensor and humidity sensor are all electrically connected with controller.

The step 200 of embodiment 2 in following steps embodiment 1:

(7-1) solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber bottom, nitrogen is filled with, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes by draft tube;

(7-2) in air chamber, be filled with by draft tube the laboratory air that known concentration of formaldehyde is S, the laboratory air that exhaust gas processing device process exports from escape pipe; Ventilate after 3 to 10 minutes, the solenoid valve that controller controls on draft tube and escape pipe all cuts out;

Controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of MQ-2 sensor, detection signal S2 (t) of MQ-135 sensor, detection signal S3 (t) of formaldehyde sensor;

(7-3) n the sample value S11 be spacedly distributed of S1 (t) chosen by controller, S12 ..., S1n, choose n the sample value S21 be spacedly distributed of S2 (t), S22 ..., S2n, choose n the sample value S31 be spacedly distributed of S3 (t), S32 ..., S3n;

Utilize formula

Di ²=(Sli-S) ²+ (S2i-S) ²+ (S3i-S) ², i=1,2 ..., n, calculated difference distance di ²;

Utilize following formula $A=\left[\begin{array}{c}{(S11-S)}^2\\ {(S12-S)}^2\\ .\\ .\\ .\\ {(S1n-S)}^2\end{array}\right],B=\left[\begin{array}{c}{(S21-S)}^2\\ {(S22-S)}^2\\ .\\ .\\ .\\ {(S2n-S)}^2\end{array}\right],C=\left[\begin{array}{c}{(S31-S)}^2\\ {(S32-S)}^2\\ .\\ .\\ .\\ {(S3n-S)}^2\end{array}\right],$ $D=\left[\begin{array}{c}d{1}^2\\ d{2}^2\\ .\\ .\\ .\\ {\mathrm{dn}}^2\end{array}\right]$ Compute matrix A respectively, B, C and D; Minimum threshold e is provided with, to A, B, C, D, concentration of formaldehyde table that temperature and humidity is relevant in storer;

(7-4) controller inquires about concentration of formaldehyde s ' according to the temperature of A, B, C, D, detection and the humidity of detection by concentration of formaldehyde table,

When data in A have 80%≤e at least and in D data have 80%≤e at least and time, the solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber, be filled with nitrogen by draft tube, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes, proceed to step 300; Otherwise, proceed to step (7-1).

Should be understood that the present embodiment is only not used in for illustration of the present invention to limit the scope of the invention.In addition should be understood that those skilled in the art can make various changes or modifications the present invention, and these equivalent form of values fall within the application's appended claims limited range equally after the content of having read the present invention's instruction.

Claims (10)

1. concentration of formaldehyde pick-up unit in a laboratory, it is characterized in that, comprise controller (1), storer (25), base plate (2), be located at air chamber (3), exhaust gas processing device (28) and bracing frame (4) that xsect on base plate is rectangular, be located at the guide frame (5) on bracing frame and cross lead screw (6);

Described air chamber inwall top is provided with for several fans (7) to canyon, air chamber madial wall is provided with at least 2 layers of gas sensitization film (8) from top to bottom successively, for supporting the wire netting (9) be made up of heating wire of gas sensitization film, be positioned at wire netting bottom and air chamber be divided into upper and lower two-part horizontal baffle (10), air chamber inner bottom part is provided with supporting plate (11), detection head (13) and the track (12) along splint upper surface Spiral distribution, detection head is provided with MQ-2 sensor (20), MQ-135 sensor (21) and formaldehyde sensor (22), gas sensitization film is provided with several through holes, and the air chamber inwall corresponding with gas sensitization film location is provided with some air guide vertical slots,

Cross lead screw one end is connected with the rotating shaft of the first motor (14) be located on bracing frame, described air chamber is provided with the opening for inserting horizontal baffle, horizontal baffle outer end is provided with web joint (15), detection head bottom is provided with the second motor (16) for driving detection head orbital motion, web joint is connected with wire rod thread, web joint and guide frame are slidably connected, and are positioned at the draft tube (23) on the air chamber of horizontal baffle upper and lower and escape pipe (24); Draft tube and escape pipe are equipped with solenoid valve (17); Hermetically-sealed construction is provided with between opening and horizontal baffle;

Also comprise the vertical screw mandrel (26) between being located at bottom supporting plate and air chamber, vertical screw mandrel top and supporting plate threaded engagement, vertical screw mandrel bottom is connected with air chamber by the bearing be located at bottom air chamber, and screw mandrel lower end is connected with the rotating shaft of the 3rd motor (27) be located in air chamber bottom;

Hermetically-sealed construction is provided with between opening and horizontal baffle; Exhaust gas processing device is connected with the escape pipe on air chamber top;

Controller is electrically connected with storer, each electric fan, each solenoid valve, wire netting, the first motor, the second motor, the 3rd motor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor respectively.

2. concentration of formaldehyde pick-up unit in laboratory according to claim 1, is characterized in that, also comprises and is located at temperature sensor (18) on detection head and humidity sensor (19); Temperature sensor and humidity sensor are all electrically connected with controller.

3. concentration of formaldehyde pick-up unit in laboratory according to claim 2, it is characterized in that, described track comprises substrate (121), is located at two spaced grooves (122) of upper surface of base plate, and described groove floor is provided with the tooth bar arranged at equal intervals; Be provided with bottom described detection head two with the gear (123) of fit depressions; The rotating shaft of described second motor is connected with the coupling shaft be located between two gears (124);

Described substrate is provided with the first baffle plate (125), the second baffle (126) relative with the first baffle plate; First baffle plate, second baffle are provided with corresponding guide chute (127); The coupling shaft two ends of described gear are provided with the outrigger shaft (128) of guide chute for inserting the first baffle plate, second baffle; Detection head lower surface is provided with several balls (129) with the first baffle plate, second baffle upper surface Structure deformation.

4. concentration of formaldehyde pick-up unit in laboratory according to claim 1, is characterized in that, support frame as described above comprises the U-shaped frame (41) that Open Side Down, is located at the L shape frame (42) of air chamber front and rear; Described guide frame is two crossbeams (51) be located between U-shaped frame and two L shape framves; Described web joint is rectangular, and web joint bottom is provided with for 2 through holes (151) through two crossbeams, and web joint top is provided with the screw hole (152) for coordinating with cross lead screw.

5. concentration of formaldehyde pick-up unit in the laboratory according to claim 1 or 2 or 3 or 4, is characterized in that, be provided with the cavity that several are spaced apart in gas sensitization film, be provided with the carbon nano-tube of stretching out outside gas sensitization film upper and lower surface in cavity; Exhaust gas processing device is spirit lamp.

6. the detection method of concentration of formaldehyde pick-up unit in laboratory according to claim 1, is characterized in that, comprise the steps:

(6-1) controller controls the first driven by motor cross lead screw and rotates, and cross lead screw drives horizontal baffle to move horizontally outside air chamber by web joint, and when horizontal baffle the inner being moved to contact with opening position, controller controls the first motor and quits work;

(6-2) solenoid valve that controller controls on draft tube and escape pipe was all opened, and is filled with nitrogen by draft tube in air chamber, to MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes;

(6-3) laboratory air to be detected is filled with by draft tube to air chamber Inner eycle, the laboratory air that exhaust gas processing device process exports from escape pipe; The adsorbed gas of gas sensitization film, after 5 to 15 minutes, controller controls the closed electromagnetic valve on draft tube and escape pipe;

(6-4) controller controls wire netting energising, controls each electric fan work simultaneously, and the gas of gas sensitization film absorption enters air chamber bottom, and after 5 to 8 minutes, controller controls wire netting power-off, and each electric fan quits work;

(6-5) controller controls the first driven by motor cross lead screw rotation, cross lead screw drives horizontal baffle to move horizontally in air chamber by web joint, when horizontal baffle outer end being moved to contact with opening position to contact, controller controls the first motor and quits work;

(6-6) controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of formaldehyde sensor, detection signal S2 (t) of MQ-2 sensor, detection signal S3 (t) of MQ-135 sensor; Controller utilizes formula signal (t)=S1 ²(t)+(S1 (t)-S2 (t)) ²+ (S1 (t)-S3 (t)) ²calculating sensor merges signal signal (t);

(6-7) be previously stored with accidental resonance model and concentration of formaldehyde forecast model in storer, inputted by signal (t) in accidental resonance model, controller calculates the output signal-to-noise ratio SNR during resonance of accidental resonance model,

SNR is inputted in concentration of formaldehyde forecast model, obtain the concentration of formaldehyde of the laboratory air be detected.

7. the detection method of concentration of formaldehyde pick-up unit in laboratory according to claim 1, described also comprising is located at temperature sensor on detection head and humidity sensor; Temperature sensor and humidity sensor are all electrically connected with controller; It is characterized in that, described step (6-2) is replaced by following step:

(7-1) solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber bottom, nitrogen is filled with, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes by draft tube;

(7-2) in air chamber, be filled with by draft tube the laboratory air that known concentration of formaldehyde is S, the laboratory air that exhaust gas processing device process exports from escape pipe; Ventilate after 3 to 10 minutes, the solenoid valve that controller controls on draft tube and escape pipe all cuts out;

Controller passes through the second driven by motor detection head along rail moving, and by the 3rd driven by motor supporting plate lifting, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor detect gas signal, controller receives detection signal S1 (t) of formaldehyde sensor, detection signal S2 (t) of MQ-2 sensor, detection signal S3 (t) of MQ-135 sensor;

(7-3) n the sample value S11 be spacedly distributed of S1 (t) chosen by controller, S12 ..., S1n, choose n the sample value S21 be spacedly distributed of S2 (t), S22 ..., S2n, choose n the sample value S31 be spacedly distributed of S3 (t), S32 ..., S3n;

Utilize formula

Di ²=(S1i-S) ²+ (S2i-S) ²+ (S3i-S) ², i=1,2 ..., n, calculated difference distance di ²;

Utilize following formula compute matrix A respectively, B, C and D; Minimum threshold e is provided with, to A, B, C, D, concentration of formaldehyde table that temperature and humidity is relevant in storer;

(7-4) controller inquires about concentration of formaldehyde s ' according to the temperature of A, B, C, D, detection and the humidity of detection by concentration of formaldehyde table,

When data in A have 80%≤e at least and in D data have 80%≤e at least and time, the solenoid valve that controller controls on draft tube and escape pipe is all opened, in air chamber, be filled with nitrogen by draft tube, to temperature sensor, humidity sensor, MQ-2 sensor, MQ-135 sensor and formaldehyde sensor cleaning 5 to 10 minutes, proceed to step (6-3); Otherwise, proceed to step (7-1).

8. the detection method of concentration of formaldehyde pick-up unit in laboratory according to claim 1, it is characterized in that, the computation process of described output signal-to-noise ratio SNR comprises the steps:

Signal (t) is inputted one deck accidental resonance model

in;

Wherein, V (x, t, α) is potential function, the movement locus that x (t) is Brownian Particles, and t is run duration, and α is particle transient motion acceleration, D ₂for external noise intensity, N (t) grasps noise in being, for periodic sinusoidal signal, A ₁be signal amplitude, f is signal frequency, for phase place; A, b are the constant of setting; If

Controller calculates the first order derivative of V (x, t, α) for x, second derivative and three order derivatives, and makes equation equal 0, obtains two layers of accidental resonance model:

Setting noise intensity D ₂=0, signal (t)=0, N (t)=0; Calculate A ₁critical value be

By A ₁critical value substitute in one deck accidental resonance model, and set X ₀(t)=0, sn ₀=0, with quadravalence jade for asking rain Ge Kuta Algorithm for Solving one deck accidental resonance model, obtain

M=0,1 ..., N-1; And calculate:

(k ₁) _m＝4(aαx _m-1(t) ²-bαx _m-1(t) ³+sn _m-1(t))

Wherein, x _mt m order derivative that () is x (t), sn _m-1the value of m-1 order derivative at t=0 place of S (t), sn _m+1the m+1 order derivative being S (t), in the value at t=0 place, obtains x ₁(t), x ₂(t) ..., x _m+1the value of (t);

Controller is to x ₁(t), x ₂(t) ..., x _m+1t () carries out integration, obtain x (t), and obtains x (t) produces accidental resonance moment position x in the double-deck stochastic system of one deck accidental resonance model and two layers of accidental resonance model composition ₁value and x ₁corresponding resonance moment t ₁, optimum transient motion acceleration alpha ₁, and and t ₁and α ₁corresponding noise D ₁, D ₁for D ₂in a value;

Controller utilizes formula calculate the signal to noise ratio snr that double-deck stochastic resonance system exports; Wherein, Δ U=a ²/ 4b.

9. the detection method of concentration of formaldehyde pick-up unit in laboratory according to claim 8, it is characterized in that, controller calculates and obtains the averaged amplitude value SS of signal (t) in testing process, described A ₁≤ 0.54SS, the 9.8SS≤D in one deck accidental resonance model and two layers of accidental resonance model ₂≤ 19.5SS; A and b all≤SS.

10. the detection method of concentration of formaldehyde pick-up unit in the laboratory according to claim 6 or 7 or 8 or 9, it is characterized in that, concentration of formaldehyde forecast model is concentration of formaldehyde W=2.34+0.37 × SNR.