CN114609059B - A multi-link synchronous determination method for the determination of nitrogen tetroxide chloride content - Google Patents
A multi-link synchronous determination method for the determination of nitrogen tetroxide chloride content Download PDFInfo
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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Abstract
本发明公开了一种用于四氧化二氮氯化物含量测定的多联式同步测定方法，涉及四氧化二氮的氯化物含量测定技术领域。该多联式同步测定方法包括步骤：制取满足三级水要求的无氯蒸馏水→使用步骤S1中制得的无氯蒸馏水配制标准工作溶液和其他相关药品试剂，制作标准工作曲线→试样气化容器预备，对螺口气化瓶进行抽真空和密封冷却→称量试样气化容器的初始质量→注入定量试样至试样气化容器中→搭建多联测定组→连接氮气吹扫管路→进行同步氮气吹扫→吸收液合并及滴定→测定吸光度和氯离子含量。本发明的多联式同步测定方法通过在相同时间段开展多样次平行测定，具有数据重现性好，化验测定耗时短，氯化物含量测定数据准确的优点。
The invention discloses a multi-joint synchronous determination method for determining the chloride content of dinitrogen tetroxide, and relates to the technical field of determination of the chloride content of dinitrogen tetroxide. The multi-joint synchronous determination method comprises the steps of: preparing chlorine-free distilled water that meets the requirements of third-grade water → using the chlorine-free distilled water prepared in step S1 to prepare a standard working solution and other related pharmaceutical reagents, and making a standard working curve → preparing a sample gasification container, vacuumizing and sealing and cooling the screw-mouth gasification bottle → weighing the initial mass of the sample gasification container → injecting a quantitative sample into the sample gasification container → building a multi-joint determination group → connecting a nitrogen purge pipeline → performing synchronous nitrogen purge → merging and titrating the absorption liquid → determining the absorbance and chloride ion content. The multi-joint synchronous determination method of the present invention has the advantages of good data reproducibility, short time consumption for laboratory determination, and accurate chloride content determination data by carrying out multiple parallel determinations in the same time period.
Description
Technical Field
The invention relates to the technical field of determination of the content of dinitrogen tetroxide chloride, in particular to a multi-connection synchronous determination method for determination of the content of dinitrogen tetroxide chloride.
Background
The dinitrogen tetroxide is used as a conventional liquid propellant and is mainly used in space launching, such as missiles, space launch vehicles and the like. In liquid propellants, too high a chloride content can severely corrode the propellant fill line. In addition, the hydrogen chloride, which is the combustion product of chlorides, releases free chlorine atoms when it encounters the hydroxyl groups in nature, which are ozone-destroying catalysts that are not themselves consumed in chemical reactions, resulting in cyclic destruction of the ozone layer. Therefore, in a significant space launch task, the determination of chloride content in dinitrogen tetroxide is one of the important indicators of whether dinitrogen tetroxide can meet high-purity liquid propellants. The chloride content is measured as a necessary test item in the test task of the tetraoxide and the technical index of the method requires that the mass fraction of the chloride is not higher than 0.040 percent. The method for determining the content of the specified chloride in GJB1964A-2015 is a working curve method, and the method is also used for determining the content of the high-purity dinitrogen tetroxide for the airship. The method is based on the law of absorption of light-the law of lamberbi. I.e. when a beam of monochromatic light passes through a homogeneous solution, its absorbance of the solution is proportional to the product of the concentration of the light absorbing substance in the solution and the thickness of the liquid layer. The law of light absorption is only applicable in a certain concentration range, the absorbance and the concentration are in a linear relationship, and in spectrophotometry analysis, the linear relationship is often used for measuring the content of a substance.
In the existing technology for measuring the chloride of the dinitrogen tetroxide, about 10g of the dinitrogen tetroxide sample is required to be taken, the sample is precisely to 0.10g, then the obtained sample is injected into a gasification bottle, the dinitrogen tetroxide sample in the gasification bottle is immediately and slowly purged by nitrogen, the sample sequentially passes through two absorption bottles with water until the dinitrogen tetroxide sample in the gasification bottle is completely volatilized, finally, solutions in the two absorption bottles are collected in a beaker, a relevant indicator and an auxiliary reagent are added, the beaker is placed on a closed electric furnace to be heated and evaporated until the sample is nearly dry, and then, the measurement of the chloride content in the dinitrogen tetroxide is completed through a spectrophotometry and an established standard working curve.
In the actual measurement of the chloride content, it is often found that the linearity of the standard curve is poor, and even if the absorbance of the spectrophotometer is adjusted to zero point by using a blank solution as a reference solution, the standard curve is still shifted upward.
In addition, the sampling of 10g of sample is a difficult problem, and the prior practice is to measure a certain volume of dinitrogen tetroxide sample by using a measuring cylinder according to experience, pour the sample into a gasification bottle at one time, and obtain the mass of the actual sample in the gasification bottle according to a differential method. In the actual weighing process, the quality of the gasified bottle filled with the sample is difficult to stabilize under the room temperature condition, and the final reading and experimental result are greatly disturbed. Meanwhile, in the subsequent nitrogen purging process, due to continuous blowing of nitrogen and self vapor pressure of dinitrogen tetroxide at normal temperature, the air pressure in the gasification bottle can be increased, and the glass plug of the gasification bottle is very likely to be sprung out under the action of internal pressure, so that the damage of the glass plug and the leakage of dinitrogen tetroxide gas are caused, and the continuity and accuracy of the subsequent chloride content measurement are affected. On the other hand, because the production technology level is limited, the sealing joint cannot be realized between the plug opening and the glass plug of the gasification bottle, partial leakage can be caused in the nitrogen purging process, although the sealing effect can be enhanced by smearing the sealing grease on the bottle opening, the possibility that the glass plug is loose still exists in the nitrogen purging process, and the complete gasification of the dinitrogen tetroxide sample under the sealing condition cannot be ensured, so that the failure rate of the chloride content measurement is higher.
In addition, in the measurement of the chloride content specified in GJB1964A-2015, at least 3 samples should be taken per sample, and the measurement of the chloride content can be completed by removing the time taken for preparing the relevant pharmaceutical agent, the time taken for debugging the spectrophotometer, the time taken for preparing the standard curve, and the like, taking 4 hours per sample for completing the test, and at least 12 hours per sample. However, in practical tests, the results of the chloride content measurement are not very ideal, mainly because the parallelism of the results of the chloride content measurement is not high, the randomness of the data is high, so that the practical tests need to be carried out for repeated measurement for many times, and the satisfactory test results can be obtained only by carefully screening and comparing the obtained data processing results. This is clearly not feasible in a practical task assay, and cannot meet the requirements of ultra-high strength, ultra-high density, ultra-high difficulty rapid assay capability. The analytical reasons may be:
(1) The poor tightness of the gasification bottle and the absorption bottle leads to the escape of part of sample gas, so that the content of chloride in the parallel measurement sample is difficult to be kept uniform, and the randomness is increased;
(2) Although the distilled water is filtered by the ion exchange resin, the possibility that the distilled water contains chloride ions still exists, and the standard working curve and the actual measurement of the chloride content are interfered to a certain extent;
(3) Each time the nitrogen gas flow is inconsistent in parallel measurement, the speed of the chloride entering the water in the absorption bottle is inconsistent, and further the difference of the absorption rate of the water to different times is caused, so that the parallelism of the actual measurement result of the chloride content is poor.
If the chloride content of 2 or more samples is measured simultaneously, the measurement time is longer, the test result cannot be obtained in a short time, and a large psychological stress is caused to the test staff, so that the accurate test result cannot be obtained in the first time.
Disclosure of Invention
In order to solve the defects of the technology, the invention provides a multi-connection synchronous determination method for determining the content of the dinitrogen tetroxide.
The technical scheme adopted by the invention for realizing the technical effects is as follows:
A multi-connected synchronous determination method for determining the content of dinitrogen tetroxide comprises the following steps:
s1, connecting a distillation device, redistilling purified water prepared by an ultra-pure water machine, and collecting prepared chlorine-free distilled water;
S2, preparing a standard working solution and other related medicine reagents by using the chlorine-free distilled water prepared in the step S1, and preparing a standard working curve;
S3, taking a screw gasification bottle, vacuumizing the bottle, and sealing and cooling the bottle for 3 hours in a 0 ℃ environment for standby;
s4, taking out the screw gasification bottle, and weighing the mass of the screw gasification bottle;
S5, connecting the sampling bottle filled with the dinitrogen tetroxide with the screw gasification bottle through a polytetrafluoroethylene tube, firstly opening a valve of the sampling bottle, then slowly opening an air inlet of the screw gasification bottle (1), enabling the dinitrogen tetroxide sample to slowly flow into the screw gasification bottle until reaching a specified volume scale mark, and then weighing the mass of the screw gasification bottle filled with the sample again;
S6, connecting the screw gasification bottles in the step S5 in series with absorption bottles with 40mL of chlorine-free distilled water in advance in the two bottles to form a combined measurement set, wherein the measurement set is at least arranged in a triple way and is arranged on a refrigerating and heating instrument;
S7, connecting the gas outlet of the nitrogen cylinder with a multi-connected pipe with at least three gas outlets, wherein each branch gas outlet of the multi-connected pipe is connected with a small flowmeter, and the outlet end of the small flowmeter is connected with a screw gasification cylinder in a one-connected measurement group on a corresponding route;
S8, regulating the temperature of the refrigerating and heating instrument (3) to 10 ℃, opening an air outlet control valve of a nitrogen cylinder, regulating the pressure to a proper range through a pressure stabilizing device, regulating a knob of a small flowmeter, uniformly emitting bubbles in each absorption bottle at a rate of 2 bubbles per second, and controlling the flow of the flowmeter among parallel measurement samples to be the same value;
S9, immediately combining the absorption liquid of the corresponding sample in each combined measurement group after the sample in the screw gasification bottle is completely volatilized, respectively placing the combined measurement groups in a beaker, adding 3 drops of 2, 4-dinitrophenol indicator solution, and neutralizing to yellow by using ammonia water to obtain a final point;
S10, placing the beaker in the step S9 in a heating zone of a refrigerating and heating instrument to evaporate until 20mL of solution remains, measuring the absorbance of the solution according to a standard working curve manufacturing process, and finding out the corresponding chloride ion content according to the working curve.
Preferably, in the method for determining the content of the dinitrogen chloride tetroxide in a multi-connection type synchronous manner, the ultrapure water machine in the step S1 adopts a reverse osmosis membrane technology, and the prepared chlorine-free distilled water meets the three-level water requirement.
Preferably, in the method for determining the content of the dinitrogen chloride tetraoxide in the multi-connection type synchronous determination method, the nitrogen gas in the nitrogen gas cylinder in the step S7 is ensured to be sufficient, so that the maximum pressure of the nitrogen gas cylinder can reach 15MPa, the nitrogen gas is convenient for long-term use, and the content of the nitrogen gas is at least 99.99% by volume fraction.
Preferably, in the multi-connected synchronous measurement method for measuring the content of the dinitrogen chloride tetroxide, the nitrogen pressure stabilizing device is connected between the air outlet of the nitrogen cylinder and the air inlet of the multi-connected pipe, and the air outlet end of the nitrogen cylinder is provided with a two-stage pressure reducer for roughly controlling the air outlet flow of the nitrogen cylinder.
Preferably, in the multi-connected synchronous measurement method for measuring the content of the dinitrogen tetroxide, the flow range of the small-sized flowmeter is controlled to be 2.5-25 mL/min.
Preferably, in the above-mentioned multi-unit synchronous measurement method for measuring the content of dinitrogen tetroxide, in the step S5, when the dinitrogen tetroxide sample in the sampling bottle is introduced into the screw gasification bottle, the method is completed as soon as possible by a standard operation method, and the quality of the screw gasification bottle is prevented from being changed due to the temperature rise.
Preferably, in the multi-connected synchronous determination method for determining the content of the dinitrogen chloride tetroxide, the screw gasification bottle comprises a glass bottle body with a screw, and a polytetrafluoroethylene bottle cap screwed on the screw of the glass bottle body, scale marks are arranged on the glass bottle body, a slow flow glass tube with a sealed upper end is connected to the middle of the bottle cap in a penetrating way, an air inlet interface tube is formed on one side of the slow flow glass tube, an air outlet tube interface communicated with the slow flow glass tube is formed on the other side of the slow flow glass tube, a nitrogen purging tube with the lower end extending to the bottle bottom position is integrally formed in the glass bottle body by the air inlet interface tube, and polytetrafluoroethylene plug valves are arranged on the air inlet interface tube and the air outlet tube interface.
Preferably, in the multi-connected synchronous measurement method for measuring the content of the dinitrogen chloride, the refrigeration and heating instrument comprises a sample refrigerator and an absorption liquid heater which are assembled in a split mode, the sample refrigerator comprises an assembled shell and a shell base, an installation opening is formed in the upper surface of the shell, a cold groove is fixed on the installation opening, a refrigeration tray, a cold plate, a semiconductor refrigeration sheet and radiating fins which are tightly attached to each other are sequentially arranged in the cold groove from top to bottom, the cold end of the semiconductor refrigeration sheet is tightly attached to the lower surface of the cold plate, the hot end of the semiconductor refrigeration sheet is tightly attached to the upper surface of the radiating fins, a refrigeration groove for fixing the screw gasification bottle is formed in the refrigeration tray, a heat insulation plate for separating the inner space of the shell into an outer cavity and an inner cavity is formed in the shell, a horizontal power supply cover and a vertical fixing frame are arranged on the shell base, a circuit control board is fixed on the outer side of the vertical fixing frame, and a refrigeration power supply for electrically connecting the circuit control board and the semiconductor refrigeration sheet is arranged in the horizontal power supply cover.
Preferably, in the method for determining the content of the dinitrogen chloride tetraoxide in a multi-joint manner, the absorption liquid heater includes a housing with an opening at an outer end, the outer end of the housing is butt-jointed with an inner end of the housing, the housing is provided with an electric heating plate and fixing grooves distributed in an array, the fixing grooves are used for fixing the absorption bottles, the electric heating plate is used for heating beakers of the absorption liquid of the samples in the same joint determination group in the step S10, and a heating power supply is arranged in the housing at a position corresponding to the electric heating plate, and the heating power supply is connected with a heating control switch.
Preferably, in the multi-connected synchronous determination method for determining the content of the dinitrogen oxide, the cold end refrigeration temperature of the semiconductor refrigeration piece is 10 ℃.
The multi-connected synchronous determination method has the advantages that the multi-parallel determination is carried out in the same time period, the data reproducibility is good, the assay determination time is short, the chloride content determination data is accurate, the screw gasification bottles and the absorption bottles in each combined determination group are fixed through the refrigerating and heating instrument, the connection arrangement of pipelines can be facilitated, the bottle body is prevented from toppling in the pipeline connection operation, meanwhile, the constant temperature control of 10 ℃ can be carried out on the screw gasification bottles, the heating evaporation is carried out on the final sample absorption liquid, all assay determination operations do not need to be transferred among a plurality of platforms, and the determination parallelism among different samples of the same sample is further improved.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a block diagram of a screw vaporizing bottle in accordance with the present invention;
FIG. 3 is a piping layout of a triple assay set in an embodiment of the present invention;
FIG. 4 is a block diagram of an absorber bottle according to the present invention;
FIG. 5 is a perspective view of the refrigeration and heating apparatus of the present invention;
FIG. 6 is an internal structural diagram of the refrigerating and heating apparatus according to the present invention;
FIG. 7 is a perspective view of a chassis base according to the present invention;
FIG. 8 is a piping layout of a six-up assay set in an embodiment of the present invention.
Detailed Description
For a further understanding of the invention, reference should be made to the following drawings and to the accompanying examples which illustrate the invention:
In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Referring to fig. 1,2 and 3, as shown in the drawings, an embodiment of the present invention provides a multi-linked synchronous determination method for determining the content of dinitrogen tetroxide, which includes the steps of:
And S1, preparing chlorine-free distilled water, connecting the chlorine-free distilled water with a distillation device, redistilling purified water prepared by an ultrapure water machine, and collecting the prepared chlorine-free distilled water, wherein the prepared chlorine-free distilled water meets the requirements of three-stage water by adopting a reverse osmosis membrane technology.
And S2, preparing a standard working solution and other related medicine reagents by using the chlorine-free distilled water prepared in the step S1 to prepare a standard working curve, wherein the preparation of the standard working solution and the preparation of the standard working curve are specifically completed by adopting the prior art disclosed by GJB1964A-2015, and specific processes are not repeated here. The related medicine reagent comprises 2, 4-dinitrophenol indicator solution and ammonia water, and an ammonium ferric sulfate solution, a saturated mercuric thiocyanate ethanol solution and a chloride ion standard solution which are used for making a standard working curve. Specifically, the 2, 4-dinitrophenol indicator solution is prepared according to HG/T4015, the ammonia water used meets the relevant requirements in GB/T631, and the ammonium iron sulfate solution is prepared according to GB/T1279. The saturated mercuric thiocyanate ethanol solution is prepared by dissolving 100mg of mercuric thiocyanate in 100mL of 95% ethanol, filtering and storing in a dark place for standby. The preparation of the chloride ion standard solution comprises the steps of dissolving 1.649g of dry sodium chloride (meeting the requirement of GB 1253) in the chlorine-free distilled water prepared in the step S1, diluting to a scale in a 500mL volumetric flask with the chloride ion concentration of 2.0mg/mL, then transferring 1.00mL of the chloride ion solution to a 200mL volumetric flask by using a pipette, diluting to the scale by using the chlorine-free distilled water prepared in the step S1, and shaking uniformly, wherein the chloride ion concentration is 0.01mg/mL.
S3, preparing a sample gasification container, taking a screw gasification bottle 1, vacuumizing the bottle, sealing and cooling the bottle for 3 hours in a 0 ℃ environment, and keeping the bottle for standby, wherein the bottle body temperature of the screw gasification bottle 1 can be ensured to be maintained at a temperature which is obviously lower than the boiling point of dinitrogen tetroxide by sealing and cooling the bottle 1 in the 0 ℃ environment in advance, so that the dinitrogen tetroxide is prevented from volatilizing in the subsequent sample injection process.
Step S4, weighing the initial mass of the sample gasification container, taking out the screw gasification bottle 1, and weighing the mass.
S5, injecting quantitative samples into a sample gasification container, connecting a sampling bottle filled with dinitrogen tetroxide with a screw gasification bottle 1 through a polytetrafluoroethylene tube, firstly opening a valve of the sampling bottle, then slowly opening an air inlet of the screw gasification bottle 1, enabling the dinitrogen tetroxide samples to slowly flow into the screw gasification bottle 1 until reaching a specified volume scale mark, and then weighing the mass of the screw gasification bottle 1 filled with the samples again. For convenient observation, the volume scale mark on the screw gasification bottle 1 is marked with a protruding scale mark at the position corresponding to 7mL, so that an experimenter can better observe the injection terminal point when injecting quantitative samples into the screw gasification bottle 1. The method has the advantages that 10g of sample is weighed, the traditional sampling method adopts a mass difference method to control the sampling value, and the mass weighing method is not easy to accurately control, so that the problem of digital display jumping of an electronic scale is solved, gasification leakage of the sample is generated, and the continuity and accuracy of the subsequent chloride content measurement are affected. Specifically, under the condition of 20 ℃, the density of the dinitrogen tetroxide is 1.446g/mL, the mass of the oxidized dinitrogen tetroxide sample is estimated according to 10g, and the sampling volume of the dinitrogen tetroxide can be obtained according to a density calculation formula to be about 7mL.
And S6, constructing a multi-unit measuring group, connecting the screw gasification bottle 1 in the step S5 in series with two absorption bottles 2 filled with 40mL of the chlorine-free distilled water prepared in the step S1 in advance, and forming a one-unit measuring group 10, wherein the one-unit measuring group 10 is used for measuring one sample. Specifically, as shown in fig. 3, the measurement groups 10 are arranged at least in a triple manner, and as shown by "A, B, C" shown in fig. 3, each measurement group 10 is placed on the refrigeration and heating apparatus 3, respectively. The refrigerating and heating instrument 3 provides a fixing function for the screw gasifying bottle 1 and the absorbing bottle 2, so that the screw gasifying bottle-absorbing bottle of each combined measuring group 10 is on a straight line path, and the subsequent pipeline connection operation is convenient. On the other hand, the refrigerating and heating instrument 3 can also provide a constant temperature refrigerating condition of 10 ℃ for the screw gasification bottle 1, can prevent the sample from being excessively high in temperature and affecting the evaporation speed, and can keep the sample in a stable and volatile state. Meanwhile, the refrigerating and heating instrument 3 can heat the subsequent sample absorption liquid, so that the assay and measurement operation is completed on the same platform.
Step S7, connecting a nitrogen purging pipeline, as shown in FIG. 3, connecting the air outlet of the nitrogen bottle 5 with a multi-connected pipe 4 with at least three air outlets, wherein each branch air outlet of the multi-connected pipe 4 is connected with a small flow meter 6, and the outlet end of the small flow meter 6 is connected with the screw gasification bottle 1 in a one-joint measuring group 10 on the corresponding pipeline.
And S8, synchronous nitrogen purging is carried out, the temperature of the refrigeration and heating instrument 3 is regulated to 10 ℃, the air outlet control valve of the nitrogen bottle 5 is opened, the pressure is regulated to a proper range through the nitrogen pressure stabilizing device 7, the knob of the small flowmeter 6 is regulated, the bubbles in each absorption bottle 2 are uniformly discharged at the rate of 2 bubbles per second, and the sample nitrogen in the screw gasification bottle 1 of each combined measurement group 10 is purged. The flow rates of the small flow meters 6 in the three groups of samples to be measured in parallel are controlled to be the same value for each of the measurement groups 10. By controlling the purge speed of nitrogen through the small flow meter 6, the stable purge of nitrogen to the sample in the screw gasifier 1 can be better controlled.
And S9, merging and titrating the absorption liquid, immediately merging the absorption liquid of the corresponding sample in each combined measurement group 10 after the sample in the screw gasification bottle 1 is completely volatilized, respectively placing the merged absorption liquid into a beaker, adding 3 drops of 2, 4-dinitrophenol indicator solution, and neutralizing with ammonia water until the color reaches yellow, thus obtaining the end point.
And S10, measuring absorbance and chloride ion content, placing the beaker in the step S9 in a heating zone of a refrigerating and heating instrument 3 to evaporate until 20mL of solution remains, measuring the absorbance of the solution according to a standard working curve manufacturing process, and finding out the corresponding chloride ion content from the working curve.
Further, in the preferred embodiment of the present invention, it is necessary to ensure that the nitrogen gas in the nitrogen cylinder 5 in step S7 is sufficient to make the maximum pressure thereof reach 15MPa, so that the nitrogen cylinder is convenient for long-term use, so that the gas consumption time required for parallel measurement of at least three groups of samples of one sample is completed, and the nitrogen content is at least 99.99% by volume fraction.
Further, in the preferred embodiment of the present invention, as shown in fig. 3, in order to ensure a stable gas source is provided to the pipeline, the nitrogen pressure stabilizing device 7 is connected between the gas outlet of the nitrogen cylinder 5 and the gas inlet of the manifold 4, and the appropriate gas supply pressure can be adjusted according to the pipeline composition and the number of test samples. In order to further improve the air supply flow, the air outlet of the nitrogen cylinder 5 is also connected with a two-stage pressure reducer (not shown in the figure), through which the air outlet flow of the nitrogen cylinder 5 can be roughly controlled.
Further, in the preferred embodiment of the present invention, the flow rate range of the small flow meter 6 is controlled to be 2.5-25 mL/min. In step S5, when the dinitrogen tetroxide sample in the sampling bottle is introduced into the screw gasification bottle 1, the operation is completed as soon as possible by the standard operation method, so as to avoid the quality change of the screw gasification bottle 1 caused by gas leakage due to temperature rise.
Further, in the preferred embodiment of the present invention, as shown in fig. 2, the screw vaporizing bottle 1 comprises a glass bottle body 11 having a screw port and a polytetrafluoroethylene bottle cap 12 screw-coupled to the screw port of the glass bottle body 11. Specifically, the glass bottle 11 is provided with scale marks, and the scale marks are marked with protruding scale marks at positions corresponding to the scale marks of 7mL so as to facilitate the observation of experimenters. The middle part of the bottle cap 12 is connected with a slow flow glass tube 13 with a closed upper end in a sealing and penetrating way, one side of the slow flow glass tube 13 is formed with an air inlet interface tube 131, and the other side is formed with an air outlet tube interface 132 communicated with the slow flow glass tube 13. Specifically, the inlet port tube 131 is integrally formed with a nitrogen purge tube 1311 having a lower end extending to a bottom position in the glass bottle 11. In order to control the on-off of the air inlet and the air outlet, polytetrafluoroethylene plug valves 14 are arranged on the air inlet interface pipe 131 and the air outlet pipe interface 132. The plug valve 14 on the screw gasification bottle 1 uses a plug valve body with a through hole as an opening and closing piece, and when the through hole faces to the direction of the air inlet pipeline, fluid can pass through the plug valve body. As a preferred embodiment, the air inlet interface tube 131, the air outlet tube interface 132 and the slow flow glass tube 13 are integrally formed, the bottom of the glass bottle body 11 is a round-mouth bottle bottom, and the volume of the glass bottle body 11 is 20-30 mL. Specifically, in step S5, the sampling bottle containing dinitrogen tetroxide and the screw gasification bottle 1 are connected through a polytetrafluoroethylene tube, the plug valve 14 on the outlet tube interface 132 of the screw gasification bottle 1 is closed, the sampling bottle valve is opened, and then the plug valve 14 on the air inlet interface tube 131 of the screw gasification bottle 1 is slowly opened, i.e. the air inlet of the screw gasification bottle 1 is opened, so that the dinitrogen tetroxide sample slowly flows into the screw gasification bottle 1. When the specified volume scale mark is reached, the plug valve 14 on the intake port pipe 131 is closed.
Further, in the preferred embodiment of the present invention, as shown in fig. 4, the structure of the absorption bottle 2 is similar to that of the screw gasification bottle 1, and comprises a glass absorption bottle body 21, a polytetrafluoroethylene absorption bottle cap 22 connected to the glass absorption bottle body 21, and an air inlet pipe 23 and an air outlet pipe 24 communicated with the glass absorption bottle body 21 through the polytetrafluoroethylene absorption bottle cap 22, wherein the lower end of the air inlet pipe 23 is close to the bottle bottom, and the lower end of the air outlet pipe 24 is close to the bottle mouth. In order to keep high absorptivity, the solution level cannot be too low, and the volume of the glass absorption bottle body 21 is 50-60 mL.
Further, in the preferred embodiment of the present invention, as shown in fig. 5, the refrigerating and heating apparatus 3 comprises a sample refrigerator 31 and an absorption liquid heater 32 which are assembled separately, the sample refrigerator 31 is used for fixing the screw vaporization bottle 1 and providing constant temperature refrigeration of 10 ℃, and the absorption liquid heater 32 is used for fixing the absorption bottle 2 and heating the absorption liquid after the sample in the screw vaporization bottle 1 is gasified. Specifically, as shown in fig. 5, the sample refrigerator 31 includes an assembled housing 311 and a housing base 312. Specifically, the upper surface of the housing 311 is formed with a mounting opening 3111, a cooling slot 313 is fixed to the mounting opening 3111, and a cooling tray 314, a cooling plate 315, a semiconductor cooling plate 316, and a heat dissipating fin 317 are sequentially and closely attached to the cooling slot 313 from top to bottom. Wherein, the cold end of the semiconductor refrigeration piece 316 is closely contacted with the lower surface of the cold plate 315, and the hot end of the semiconductor refrigeration piece 316 is closely contacted with the upper surface of the heat dissipation fin 317. In the preferred embodiment of the present invention, the cold side refrigeration temperature of the semiconductor refrigeration sheet 316 is 10 ℃. The refrigerating tray 314 is provided with a refrigerating groove 3131 for fixing the screw gasifying bottle 1, the groove edge of the refrigerating groove 3131 is provided with clamping reeds 33 with elastic deformation, the number of the clamping reeds 33 is three, and the clamping reeds are distributed on the groove edge of the refrigerating groove 3131 in an equidistant annular mode. The clamping reed 33 can fix the screw gasification bottle 1 with the bottle bottom placed in the refrigerating groove 3131 on one hand, and can better refrigerate the screw gasification bottle 1 through contacting with the glass bottle 11. As shown in fig. 6, a heat shield 3114 is formed in the housing 311 to partition the housing interior space into an outer chamber 3112 and an inner chamber 3113, a horizontal power source cover 318 and a vertical mount 3121 are provided on the housing base 312, a circuit control board 319 is fixed to the outer surface of the vertical mount 3121, and a cooling power source electrically connected to the circuit control board 319 and the semiconductor cooling fin 316 is provided in the horizontal power source cover 318. After the housing 311 is assembled and fixed with the housing base 312, the heat-insulating plate 3114 separates the horizontal power cover 318 and the vertical fixing frame 3121 in two different spaces, so that the circuit control board 319 corresponds to the outer cavity 3112, the power source for refrigeration corresponds to the inner cavity 3113, and adverse effects on the circuit control board 319 caused by heat emitted by the heat-dissipating fins 317 can be avoided. The horizontal power cover 318 is made of heat insulation material, and is horizontally arranged at the bottom of the inner cavity 3113, so that heat dissipated by the heat dissipation fins 317 can be prevented from being concentrated on the power supply for refrigeration, the left side wall of the inner cavity 3113 corresponding to the shell 311 is further provided with a heat dissipation through hole (not shown in the figure) communicated with the outside, and an exhaust fan is arranged at the inner side of the heat dissipation through hole, so that the heat in the inner cavity 3113 can be dissipated. To further prevent heat from entering the outer cavity 3112 from the inner cavity 3113, the housing base 312 is further provided with a sealing slot 3122 between the horizontal power cover 318 and the vertical mount 3121, and the lower edge of the heat shield 3114 is adapted to fit into the sealing slot 3122 to isolate the inner cavity 3113 from the outer cavity 3112 when the housing 311 and the housing base 312 are assembled and connected.
Further in the preferred embodiment of the present invention, as shown in FIG. 7, the absorption liquid heater 32 comprises a housing with an open outer end, the outer end of the housing being butt-fitted with the inner end of the housing 311. Specifically, the housing is provided with an electric heating plate 322 and fixing grooves 321 distributed in an array. The fixing groove 321 is used for fixing the absorption bottle 2, for better fixing the absorption bottle 2, the clamping reeds 34 with elastic deformation are arranged on the groove edges of the fixing groove 321, the number of the clamping reeds 34 is three, the same structure of the clamping reeds 34 and the same structure of the clamping reeds 33 are distributed on the groove edges of the fixing groove 321 in an equidistant annular mode. The electric heating plate 322 is used for heating the beakers for combining the sample absorption liquids in the same combined measurement set 10 in step S10, that is, the absorption liquids of the two absorption bottles 2 in the combined measurement set "a" in fig. 2 are combined in one beaker a, the absorption liquids of the two absorption bottles 2 in the combined measurement set "B" are combined in one beaker B, the absorption liquids of the two absorption bottles 2 in the combined measurement set "C" are combined in one beaker C, then the beaker a, the beaker B and the beaker C are heated respectively, evaporated until the residual absorption liquid in the beaker is 20mL, and then the absorbance of the solution is measured according to the standard working curve manufacturing process, and the corresponding chloride ion content is detected by the working curve. Specifically, as shown in fig. 5, a heating power supply 324 is provided in the housing at a position corresponding to the electric heating plate 322, and a heating control switch 325 is connected to the heating power supply 324.
As some other embodiments of the present invention, as shown in fig. 8, a six-way measurement set may be further provided, including two multi-way pipes 4 having three air outlets and one two-way pipe 41 having two air outlets, where the multi-way pipe 4 has one air inlet pipe, three air outlet branch pipes, one air inlet pipe for the two-way pipe 41, and two air outlet branch pipes. Specifically, the air inlet pipes of the two multi-connected pipes 4 are respectively connected with the two air outlet branch pipes of the two branch pipes 41, the three air outlet branch pipes of one multi-connected pipe 4 are respectively connected with one multi-connected measurement group 10, and one multi-connected pipe 4 corresponds to the three multi-connected measurement group 10, through which the measurement of 6 groups of samples of the two samples can be synchronously completed in parallel.
Specifically, in the preferred embodiment of the invention, the linear correlation degree of the prepared standard working curve of the relevant solution prepared by the chlorine-free distilled water can reach 0.9994 at most, and the standard working curve passes through the origin, so that compared with the standard working curve obtained by ultra-pure water without distillation, the standard working curve is much better, and the condition that the standard working curve moves upwards and does not pass through the origin is avoided.
Further, in the preferred embodiment of the present invention, in order to shorten the experimental period, multiple parallel measurements are performed for the same period of time, and at the same time, the sample temperature is prevented from being too high to affect the evaporation rate, and the screw-type gasifying bottle 1 is placed in the refrigerating tank 3131, and constant-temperature refrigeration at 10 ℃ is provided for the screw-type gasifying bottle, so that the sample can be kept in a stable volatile state. The gas flow rate of the screw gasification bottle 1 at the gas inlet is further regulated by a small-sized flowmeter 6, so that the gas inlet pressure consistency between parallel measurement is ensured. By the above improvement, the results of the first 6 repeated assays were compared with the data of 6 parallel experiments performed at the same time after the improvement, as shown in tables 1 and 2.
TABLE 1
TABLE 2
As can be seen from tables 1 and 2, although the maximum difference before improvement meets the requirement of not more than 0.004%, the result of the parallel measurement experiment is not ideal, and the result of the parallel measurement experiment can be seen from the result of the relative standard deviation, the relative standard deviation reaches 10.29%, which shows that the repeatability of experimental data of the original method is poor, and only data meeting the requirement can be screened out from multiple experimental data, so that the method is not feasible, and the assay efficiency is greatly reduced.
The maximum difference and the relative standard deviation after improvement are much smaller, and experimental data meet the test requirements. Even if the chloride content is so small, the parallel measurement result requirement can be met well. The method before improvement is not problematic from the data point of view, and once the chloride content is high, the method is extremely poor to meet the requirements.
In addition, the test time before and after the improvement of the analysis can be known that the total time spent for 6 repeated experiments is 24 hours, and the test time spent for the improvement is shortened to 4 hours, thereby greatly shortening the test period. Under the condition of more test samples, the test requirements can be met simultaneously by only increasing the branching quantity of the pipelines, namely the number of the test groups 10, and the rapid test of the content of various chlorides can be carried out.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the foregoing embodiments, but rather, the foregoing embodiments and description illustrate the principles of the invention, and that various changes and modifications may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
Claims (10)
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| CN110813032A (en) * | 2019-09-28 | 2020-02-21 | 中国人民解放军63605部队 | Intelligent self-regulation and control absorption device for dinitrogen tetroxide waste liquid |
| CN112229802A (en) * | 2020-07-31 | 2021-01-15 | 中国人民解放军63605部队 | Method for quantifying concentration of nitrite nitrogen and nitrous acid in nitroxide wastewater |
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| CN110813032A (en) * | 2019-09-28 | 2020-02-21 | 中国人民解放军63605部队 | Intelligent self-regulation and control absorption device for dinitrogen tetroxide waste liquid |
| CN112229802A (en) * | 2020-07-31 | 2021-01-15 | 中国人民解放军63605部队 | Method for quantifying concentration of nitrite nitrogen and nitrous acid in nitroxide wastewater |
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