Full-automatic sulfur dioxide detector

Abstract

A sulfur dioxide detector is provided, comprising: a test tube; a steam generator for maintaining the distillate in a state of complete boiling; a nitrogen generator for generating nitrogen and applying it into the test tube; a first condenser connected to the test tube, and nitrogen carrying sulfur dioxide and water vapor enter the first condenser from the test tube; a second condenser connected in series with the first condenser; a reaction cup containing an absorbent solution and a color indicator, and nitrogen and sulfur dioxide from the second condenser are introduced into the absorbent solution; and a titration unit for titrating a standard alkali solution into the absorbent solution and calculating the sulfur dioxide content in the sample. The system is provided with two-stage condensers, which improves the separation and removal efficiency of water vapor, avoids the interference and influence of water vapor on subsequent titration detection, improves the detection accuracy of sulfur dioxide content, and at the same time, complete boiling speeds up the volatilization rate of sulfur dioxide, improving the detection efficiency.

Description

Technical Field

[0001] The present invention relates to the field of sulfur dioxide detection, and in particular to a sulfur dioxide detector, especially a fully automatic sulfur dioxide detector. Background Art

[0002] The safety and health of food and medicinal materials have been increasingly emphasized. Among them, the content of sulfur dioxide in food and medicinal materials needs to be specifically detected. In the prior art, the sample to be detected is placed in a test tube, diluted hydrochloric acid is added, and the sample is heated and distilled. The sulfur dioxide gas is distilled out of the liquid surface and is pushed into the condenser by nitrogen. The condenser condenses the water vapor generated by distillation and returns it to the test tube, while the sulfur dioxide is pushed by nitrogen into a collection container such as a reaction cup and is absorbed by the absorbent solution added with a color reagent, thereby realizing the collection of sulfur dioxide, and then manually titrated by the tester. For example, in the existing national food sulfur dioxide detection standard, it is stipulated that when heating and distilling the sample, the distillate (such as hydrochloric acid solution) needs to be kept in a "gentle boiling" state, and the distillation time is 90 - 120 minutes. However, the "gentle boiling" state is difficult to standardize and control, the distillation time is long and the efficiency is low, the composition and content of the collected gas are difficult to accurately control, and the error of the subsequent manual titration detection result is relatively large.

[0003] Therefore, it is necessary to study a sulfur dioxide detector to solve one or more of the above technical problems. Summary of the Invention

[0004] To solve at least one of the above technical problems, the applicant has found through research that the water vapor from the distillate in the prior art often enters the reaction cup together with nitrogen and sulfur dioxide, thus diluting the color of the color reagent in the reaction cup, and the judgment of the acid-base balance end point will drift and cause errors during the titration detection. Therefore, according to one aspect of the present invention, a sulfur dioxide detector is provided, which is characterized by including:

[0005] A test tube for containing the distillate and the sample;

[0006] A steam generator for generating steam and heating the distillate and the sample with the steam to maintain the distillate in a full boiling state;

[0007] A nitrogen generator for generating nitrogen and applying it into the test tube;

[0008] A first condenser connected to the test tube, and nitrogen carrying sulfur dioxide and water vapor enters the first condenser from the test tube;

[0009] A second condenser connected in series with the first condenser;

[0010] A reaction cup containing an absorbent solution and a color indicator, and nitrogen and sulfur dioxide from the second condenser are introduced into the absorbent solution; and

[0011] A titration unit for titrating a standard alkali solution into the absorption solution and calculating the sulfur dioxide content in the sample.

[0012] According to another aspect of the present invention, the sulfur dioxide detector further includes a distillation end determination unit for determining that the sulfur dioxide in the sample is completely distilled.

[0013] According to another aspect of the present invention, the distillation end determination unit determines the end of distillation based on the working duration of the steam generator, the working duration being a first predetermined time, and the first predetermined time being 5 - 60 minutes.

[0014] According to another aspect of the present invention, the sulfur dioxide detector further includes an acid - base equilibrium point automatic judgment unit, and the acid - base equilibrium point automatic judgment unit includes a light - emitting unit disposed on the first side of the reaction cup and a color sensor located on the second side of the reaction cup.

[0015] According to another aspect of the present invention, the sulfur dioxide detector further includes a distillation spectrum unit for drawing a color frame according to the real - time color of the color indicator and plotting the titration speed of the standard alkali solution recorded in real - time as a bar chart for display on a display.

[0016] According to another aspect of the present invention, the sulfur dioxide detector further includes a titration control unit for controlling the titration speed of the standard alkali solution to decrease from fast to slow, and the slow - drip interval time gradually becomes longer until there is no titration per unit time; the distillation end determination unit determines that the sulfur dioxide in the sample is completely distilled based on no titration per unit time.

[0017] According to another aspect of the present invention, a drain valve is connected to the bottom of the reaction cup.

[0018] According to another aspect of the present invention, the first predetermined time decreases as the boiling intensity of the distillate increases.

[0019] According to another aspect of the present invention, the flow rate of nitrogen gas applied into the test tube is 1 - 2 liters per minute.

[0020] According to another aspect of the present invention, the first predetermined time is 10 - 20 minutes, and the sulfur dioxide detector is a fully automatic sulfur dioxide detector.

[0021] The present invention can achieve one or more of the following technical effects:

[0022] This system can realize the automatic and real - time detection of the sulfur dioxide content in the sample;

[0023] This system is provided with two - stage condensers, avoiding the interference and influence of water vapor on subsequent titration detection and improving the detection accuracy of the sulfur dioxide content;

[0024] The complete boiling of the distillate can accelerate the volatilization rate of sulfur dioxide, improve the detection efficiency, shorten the complete extraction time of sulfur dioxide to between 5 and 60 minutes, and is convenient for operation;

[0025] The combination of complete boiling and two-stage condensation further achieves the efficient removal of water vapor and a significant improvement in detection efficiency, while reducing the detection error. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0027] Figure 1 It is a schematic structural diagram of a sulfur dioxide detector according to a preferred embodiment of the present invention.

[0028] Figure 2 It is a schematic structural diagram of an automatic acid-base balance judgment unit according to a preferred embodiment of the present invention.

[0029] Figure 3 It is a schematic structural diagram of a first condenser according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The best mode of the present invention will be described below in conjunction with the drawings through preferred embodiments. The specific embodiments herein are for explaining the present invention in detail and should not be construed as limiting the present invention. Without departing from the spirit and scope of the present invention, various modifications can be made, and all of these should be included within the protection scope of the present invention.

[0031] Embodiment 1

[0032] According to a preferred embodiment of the present invention, referring to Figure 1-2 , a sulfur dioxide detector is provided, which is characterized by including:

[0033] A test tube for containing the distillate and the sample;

[0034] A steam generator for generating steam and heating the distillate and the sample with the steam to maintain the complete boiling of the distillate;

[0035] A nitrogen generator for generating nitrogen and applying it into the test tube;

[0036] A first condenser communicating with the test tube, and nitrogen carrying sulfur dioxide and water vapor enters the first condenser from the test tube;

[0037] A second condenser connected in series with the first condenser;

[0038] A reaction cup containing an absorption liquid and a color indicator, into which nitrogen and sulfur dioxide from the second condenser are introduced into the absorption liquid; and

[0039] A titration unit for titrating a standard alkali solution into the absorption liquid and calculating the sulfur dioxide content in the sample.

[0040] According to another preferred embodiment of the present invention, the sulfur dioxide detector further includes a distillation end determination unit for determining whether the sulfur dioxide in the sample is completely distilled.

[0041] According to another preferred embodiment of the present invention, the distillation end determination unit determines the end of distillation based on the working duration of the steam generator. The working duration is a first predetermined time, and the first predetermined time is 5 - 60 minutes. It can be understood that the first predetermined time can be determined according to experience.

[0042] According to another preferred embodiment of the present invention, the sulfur dioxide detector further includes an automatic acid - base balance point judgment unit, which includes a light - emitting unit arranged on the first side of the reaction cup and a color sensor located on the second side of the reaction cup.

[0043] Preferably, the color change of the color indicator can be detected by the color sensor, and the detected data is sent to the processor in real time. The processor receives and stores the real - time color change and processes it. The detected color changes from red at the beginning to yellow at the titration end point, then the titration ends. The color reagent is methyl red, showing red in acidic conditions and yellow in alkaline conditions. Hydrogen peroxide is weakly acidic and shows red. After sulfur dioxide is absorbed, it continues to show red. As the distillation proceeds and the standard alkali titration also starts, as the alkali is titrated, the inside of the reaction cup turns yellow. At the end of distillation, it is determined again whether the acid - base balance point is reached.

[0044] According to another preferred embodiment of the present invention, the sulfur dioxide detector further includes a distillation spectrum unit for drawing a color frame based on the real - time color of the color indicator and plotting the titration speed of the standard alkali solution recorded in real time as a bar chart for display on a display. The tester can supervise the detection process and progress through this distillation spectrum.

[0045] According to another preferred embodiment of the present invention, the sulfur dioxide detector further includes a titration control unit for controlling the titration speed of the standard alkali solution to decrease from fast to slow, and the slow - drip interval time gradually becomes longer until there is no titration per unit time. The distillation end determination unit determines that the sulfur dioxide in the sample is completely distilled based on no titration per unit time.

[0046] According to another preferred embodiment of the present invention, a drain valve is connected to the bottom of the reaction cup.

[0047] According to another preferred embodiment of the present invention, the first predetermined time decreases as the boiling intensity of the distillate increases.

[0048] According to another preferred embodiment of the present invention, the flow rate of nitrogen gas applied into the test tube is 1 - 2 liters per minute.

[0049] According to another preferred embodiment of the present invention, the first predetermined time is 10 - 20 minutes, and the sulfur dioxide detector is a fully automatic sulfur dioxide detector.

[0050] It can be understood that, similar to the prior art, the test tube contains a distillate and a sample to be detected. The distillate is, for example, a hydrochloric acid solution (such as 0.3 mol / L). Measure 150 - 200 mL of hydrochloric acid and slowly pour it into the test tube containing the sample.

[0051] Preferably, the light emitting unit is a lamp, such as a composite light spectrum lamp.

[0052] According to another preferred embodiment of the present invention, the absorbent solution is a hydrogen peroxide solution, and the color indicator is a methyl red ethanol solution indicator.

[0053] According to another preferred embodiment of the present invention, the part of the reaction cup corresponding to the light emitting unit and the color sensor is made of optical glass.

[0054] According to another preferred embodiment of the present invention, the water vapor from the water vapor generator is guided to the bottom of the distillate through a pipeline.

[0055] According to another preferred embodiment of the present invention, the nitrogen gas from the nitrogen gas generator is guided to the bottom of the distillate through a pipeline.

[0056] According to another preferred embodiment of the present invention, refer to Figure 3 , the first condenser includes:

[0057] A body 2, including two or more expansion parts 22 and a neck 21 connected between adjacent expansion parts 22, and having a mixed gas inlet 23 at the first end and a mixed gas outlet 24 at the second end; and

[0058] A turbulence tube 3, disposed at the mixed gas outlet 24, with the first end 31 extending into the expansion part adjacent to the mixed gas outlet, and the second end 32 extending out of the mixed gas outlet;

[0059] Wherein, the body 2 is surrounded by a coolant, and the part of the turbulence tube 3 extending into the expansion part is composed of a vertical part and a bent part connected in sequence.

[0060] According to another preferred embodiment of the present invention, the body 2 is vertically arranged with the mixed gas inlet 23 at the lower part and the mixed gas outlet 24 at the upper part, and the opening at the first end 31 of the spoiler tube faces one side. Advantageously, the first end of the spoiler tube extends into the expansion part adjacent to the mixed gas outlet, avoiding the direct passage of gas through the outlet, changing, disturbing and increasing the gas flow path, increasing the number of times the water vapor impacts the inner wall of the body, and further improving the condensation efficiency.

[0061] The working principle of the present invention is as follows: Place the sample in a test tube. Add diluted hydrochloric acid and heat the sample for distillation to let sulfur dioxide gas be distilled out of the liquid surface. Since the molecular weight of sulfur dioxide gas is more than twice that of air, nitrogen needs to be introduced into the distillation liquid. The function of nitrogen is to push the sulfur dioxide gas into the condenser. The condenser condenses the water vapor generated by distillation and returns it to the test tube, while the sulfur dioxide is pushed by nitrogen to the reaction cup and absorbed by the absorbing liquid added with a color reagent. Then, titrate the absorbing liquid that has absorbed sulfur dioxide with a standard base, determine the acid-base equilibrium point through the color change of the color reagent, and finally calculate the sulfur dioxide content in the sample based on the volume of the standard base consumed.

[0062] The present invention can achieve one or more of the following technical effects:

[0063] This system can realize the automatic real-time detection of the sulfur dioxide content in the sample;

[0064] This system is provided with two-stage condensers, avoiding the interference and influence of water vapor on the subsequent titration detection, and improving the detection accuracy of the sulfur dioxide content;

[0065] The complete boiling of the distillation liquid can accelerate the volatilization rate of sulfur dioxide, improve the detection efficiency, shorten the complete extraction time of sulfur dioxide to between 5 and 60 minutes, and is convenient for operation;

[0066] The combination of complete boiling and two-stage condensation further realizes the efficient removal of water vapor and a significant improvement in the detection efficiency, while reducing the detection error.

[0067] Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A sulfur dioxide detector, characterized in that Comprising: A test tube for containing distillate and a sample; A steam generator for generating steam and heating the distillate and the sample with the steam to maintain the distillate in a state of complete boiling; A nitrogen generator for generating nitrogen and applying it into the test tube; A first condenser provided at the top of the test tube and communicating with the test tube. Nitrogen carries sulfur dioxide and steam to form a mixed gas, which enters the first condenser from the test tube for primary condensation and then directly passes through a second condenser for secondary condensation. The first condenser condenses the steam generated by distillation and returns it to the test tube; A second condenser in series with the first condenser and used to condense the remaining steam in the mixed gas from the first condenser and return it to the test tube to avoid interference of steam on subsequent titration detection; A reaction cup containing an absorption solution and a color indicator, and nitrogen and sulfur dioxide from the second condenser are introduced into the absorption solution; And A titration unit for titrating a standard alkali solution into the absorption solution and calculating the sulfur dioxide content in the sample.

2. The sulfur dioxide detector according to claim 1, wherein It further includes a distillation end determination unit for determining whether the sulfur dioxide in the sample is completely distilled.

3. The sulfur dioxide detector according to claim 2, characterized in that The distillation end determination unit determines the end of distillation according to the working duration of the steam generator, the working duration being a first predetermined time, and the first predetermined time being 5 - 60 minutes.

4. The sulfur dioxide detector according to any one of claims 1 to 3, characterized in that It further includes an automatic acid-base balance point judgment unit, and the automatic acid-base balance point judgment unit includes a light-emitting unit provided on the first side of the reaction cup and a color sensor located on the second side of the reaction cup.

5. The sulfur dioxide detector according to claim 4, wherein It further includes a distillation graph unit for drawing a color frame according to the real-time color of the color indicator and plotting the titration speed of the standard alkali solution recorded in real time into a bar graph for display through a display.

6. The sulfur dioxide detector according to claim 2, wherein It further includes a titration control unit for controlling the titration speed of the standard alkali solution to decrease from fast to slow, and the slow-drop interval time gradually becomes longer until there is no titration per unit time; the distillation end determination unit determines that the sulfur dioxide in the sample is completely distilled according to no titration per unit time.

7. The sulfur dioxide detector according to claim 6, characterized in that A drain valve is connected to the bottom of the reaction cup.

8. The sulfur dioxide detector according to claim 3, characterized in that The first predetermined time decreases as the boiling intensity of the distillate increases.

9. The sulfur dioxide detector according to claim 4, wherein The flow rate of nitrogen applied into the test tube is 1 - 2 liters per minute; the first condenser includes: A body including two or more expansion parts and a neck connecting adjacent expansion parts, and having a mixed gas inlet at the first end and a mixed gas outlet at the second end; and A turbulator tube provided at the mixed gas outlet, with the first end extending into the expansion part adjacent to the mixed gas outlet and the second end extending out of the mixed gas outlet; Wherein, a coolant surrounds the outside of the body, and the part of the turbulator tube extending into the expansion part is composed of a vertical part and a bent part connected in sequence.

10. The sulfur dioxide detector according to claim 3, characterized in that The first predetermined time is 10 - 20 minutes, and the sulfur dioxide detector is a fully automatic sulfur dioxide detector.

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