Method and testing device for identifying doping of inorganic sulfuric acid in organic phosphorus scale and corrosion inhibitor

Abstract

The invention discloses a method for identifying inorganic sulfuric acid doped in an organic phosphorus scale and corrosion inhibitor and a testing device, and belongs to the technical field of identification of water treatment agents. The method comprises the following steps: putting an organophosphorus scale and corrosion inhibitor sample into a testing device, and drying to obtain a treated sample; checking the state of the treated sample so as to judge whether the organic phosphorus scale and corrosion inhibitor sample is doped with inorganic sulfuric acid or not; when the treated sample is in a coexistence state of a coking film and a flow state, judging doping; obtaining the flow state and the flow state volume of the treated sample; adding water to dilute the flow state of the treated sample, obtaining the dilution flow state and the volume of the dilution flow state, measuring the pH value of the dilution flow state, and calculating the volume percentage of the inorganic sulfuric acid. According to the method, the existence of sulfuric acid is judged based on the change of the state of an organophosphorus scale and corrosion inhibitor sample after high-temperature drying.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment agent identification, and particularly relates to a method and a testing device for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor. Background Art

[0002] During cooling water circulation, the continuous flow of water causes water temperature to rise and salts to evaporate and concentrate. Under these conditions, minerals and dissolved salts can easily become supersaturated, forming crystals that deposit on pipe and equipment surfaces, reducing heat transfer efficiency and potentially blocking pipes, impacting system operation. To address this issue, organophosphorus scale inhibitors are used in water treatment. Their active ingredients include aminotris(methylenephosphonic acid) (ATMP), hydroxyethylidenediphosphonic acid (HEDP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMPA), and ethylenediaminetetramethylenephosphonic acid (EDTMPS). These organic polyacid molecules chelate with metal cations to form stable complexes, reducing calcium and magnesium ion activity and inhibiting scale formation. Compared to traditional inorganic acid scale inhibitors, organophosphorus scale inhibitors have larger molecular weights, more complex structures, and greater stability. They are less susceptible to hydrolysis and maintain their scale inhibition performance over a long period of time. Furthermore, the hydrophilic groups in their molecular structure form a protective film on metal surfaces, preventing direct contact between corrosive media and the metal, thereby mitigating corrosion damage to pipes and equipment.

[0003] However, some existing products use low-cost inorganic sulfuric acid instead of high-quality organic polyphosphate to reduce costs. However, inorganic sulfuric acid is highly corrosive, and long-term circulation can accelerate the corrosion of pipeline equipment. As corrosion intensifies, pipeline equipment may break or leak, leading to performance degradation or even failure of the entire system. Furthermore, the addition of inorganic sulfuric acid can disrupt the balanced formulation of scale and corrosion inhibitors, causing water quality deterioration and reducing treatment effectiveness.

[0004] Verifying the effectiveness of organic polyphosphates using circulating water dynamic simulation tests based on GB / T50050-2017, "Design Specification for Industrial Circulating Cooling Water Treatment," requires 15 days or even longer. Furthermore, the corrosion damage caused by the inorganic sulfuric acid mixed in organic polyphosphates is not easily apparent during such a short simulation period. The industry standard DL / T806-2013, "Scale and Corrosion Inhibitors for Circulating Water in Thermal Power Plants," does not specify sulfuric acid content in related products or methods for identifying inorganic sulfuric acid mixed in organic polyphosphates.

[0005] In the prior art, ion chromatography is usually used to detect whether sulfuric acid is mixed into organophosphorus scale inhibitors. Ion chromatography is performed by measuring the content of ions in the sample for analysis. The specific process is as follows: Sample preparation: Take a certain amount of organophosphorus scale inhibitor sample and subject it to appropriate pre-treatment, such as filtration, dilution, etc., to remove impurities that may interfere with the measurement. Ion chromatography analysis: Inject the treated sample into an ion chromatograph, and separate the ions in the sample through separation columns such as ion exchange resins. Sulfate ions have a specific retention time and peak shape in the ion chromatograph. Detection and quantification: The separated ion peaks are detected by a detector, and the sulfate ion content in the sample can be calculated based on the correspondence between the peak area or peak height and the standard sulfate ion solution. If the presence of sulfate ions is detected and the content exceeds a certain threshold, it can be considered that sulfuric acid has been mixed into the organophosphorus scale inhibitor.

[0006] However, the above-mentioned ion chromatography method is suitable for the determination of parts per million / parts per billion and micro / trace concentrations, and is not suitable for the test range of percentages and constant concentrations. It has high requirements for samples and requires precise pre-treatment operations such as filtration and dilution. If the ion types in the sample are complex or there are many impurities, interference or insufficient sensitivity may occur. In addition, the instrument requires carrier gas to operate, and has high requirements for the laboratory environment, making it unsuitable for on-site rapid detection. Summary of the Invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method and testing device for identifying inorganic sulfuric acid doped in organophosphorus scale and corrosion inhibitors, judging the presence of sulfuric acid based on the change in the state of the organophosphorus scale and corrosion inhibitor sample after high-temperature drying, and further determining the content of inorganic sulfuric acid based on the pH value of the flow state.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions: In one aspect, the present invention provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: S1: Place the organophosphorus scale and corrosion inhibitor sample into the test device for drying, and then obtain the treated sample; S2: Check the state of the treated sample to determine whether the organophosphorus scale and corrosion inhibitor sample is doped with inorganic sulfuric acid; if the treated sample shows both a coked film and a fluidized state, it is considered doped; S3: Obtain the flow state and volume of the treated sample; dilute the flow state of the treated sample with water, obtain the diluted flow state and volume of the diluted flow state, measure the pH value of the diluted flow state, and calculate the volume percentage of inorganic sulfuric acid.

[0009] In one embodiment, in S1, the drying process is performed at a temperature of 100-120° C. for a time of 4-8 hours.

[0010] In one embodiment, in S2, when the sample after treatment only shows a coked film state, it is determined that the organophosphorus scale and corrosion inhibitor is not doped with inorganic sulfuric acid.

[0011] In one embodiment, in S2, when the sample after treatment exhibits a coexistence of a charred film and a fluid state, doping is determined (further verification of the inorganic sulfuric acid doping is based on the following: hydrochloric acid is added to the fluid state, and no bubbles appear (i.e., no carbonate and sulfite are present); and then a barium chloride solution is added dropwise, and a white precipitate appears).

[0012] In one embodiment, in S3, when the fluidized state of the sample is diluted with water, the amount of water used is more than 100 times the volume of the fluidized state.

[0013] In one embodiment, in S3, the formula for calculating the volume percentage of inorganic sulfuric acid is as follows: 100%; in, is the volume percentage of inorganic sulfuric acid, 98 is the relative molecular mass of inorganic sulfuric acid, 1.84 is the density of inorganic sulfuric acid, pH is the pH value of the diluted flow state, V1 is the volume of the organophosphorus scale and corrosion inhibitor sample, and V2 is the volume of the diluted flow state.

[0014] Another aspect of the present invention provides a testing device for implementing the above-mentioned method of identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising a double-layer shell and a holding cup, each consisting of an inner layer and an outer layer. The shell comprises a first portion and a second portion connected in an upper and lower section. A control and digital display and an air inlet are provided on the top surface of the first portion. A blower and a heating wire are provided in the interior of the first portion in order from top to bottom. Air diffusion holes are provided on the bottom surface of the second part, a temperature sensor is provided on the inner layer of the second part, an hourglass-shaped holding cup is provided inside the second part, a first hole and a second hole are provided on the top surface and the side wall of the holding cup respectively, and a large plug and a small plug are provided on the first hole and the second hole respectively.

[0015] In one embodiment, the holding cup adopts an hourglass-shaped container with a concentric double-layer structure, and the holding cup is composed of a symmetrical outer hourglass body and an asymmetrical inner hourglass body with a larger upper part and a smaller lower part; the outer hourglass body is a streamlined double-cone structure that is symmetrical up and down, and the inner hourglass body is an asymmetrical frustum structure with a larger upper part and a smaller lower part.

[0016] In one embodiment, the outer hourglass body and the inner hourglass body constitute a measuring chamber, and fluid communication between the upper and lower measuring chambers is achieved through a neck with equal diameter contraction in the middle section; the measuring chamber includes an upper cone chamber of section A and a lower cone chamber of section B; the volume ratio of the upper cone chamber of section A to the volume ratio of the lower cone chamber of section B is greater than 100:1.

[0017] In one embodiment, the inner hourglass body of the holding cup is provided with scales; the first hole and the second hole are opened on the top surface and side wall of the upper cone chamber of section A.

[0018] In one embodiment, the inner layer of the first part extends relative to the outer layer of the first part to form an extended portion, the inner layer of the second part is retracted relative to the outer layer of the second part to form a retracted portion, and the extended portion and the retracted portion are adapted to achieve a sealed connection.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for identifying inorganic sulfuric acid contamination in organophosphorus scale and corrosion inhibitors. After high-temperature drying, the sample is quickly determined based on its final state. Specifically, the method first dries the organophosphorus scale and corrosion inhibitor sample and then examines the dried sample. If the sample exhibits a completely coked film, it indicates that the sample is free of inorganic sulfuric acid contamination, as under these conditions, pure organic polyphosphate undergoes a coking process to form a film. Conversely, if the sample exhibits both a coked film and a fluidized state—that is, some areas remain solid and coked while others exhibit liquid flow—this directly indicates the presence of inorganic sulfuric acid, as inorganic sulfuric acid does not coke under this high-temperature treatment but remains liquid. This method is advantageous in its speed, simplicity, and accuracy, making it particularly suitable for product quality inspection in real-world situations, such as those faced with challenging testing conditions and time constraints. By using a portable test device and visually observing the dried sample, the presence of inorganic sulfuric acid contamination in the organophosphorus scale and corrosion inhibitor can be quickly determined, avoiding the complex pretreatment steps and long testing cycles required by traditional methods such as ion chromatography. In addition, this method not only provides a basis for qualitative judgment, but also further supports the possibility of quantitative analysis. For example, by measuring the volume of the flowing part and combining it with subsequent pH value determination and specific formula calculation, the volume percentage of inorganic sulfuric acid can be accurately obtained, thereby comprehensively evaluating the degree of doping and ensuring the accuracy and effectiveness of product quality control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor provided by the present invention; Figure 2 A diagram of a testing device for identifying inorganic sulfuric acid doped in an organic phosphorus scale and corrosion inhibitor according to an embodiment of the present invention; Among them: 1-shell; 2-control and digital display; 3-air inlet; 4-blower; 5-heating wire; 6-holding cup; 7-temperature sensor; 8-large plug; 9-small plug; 10-air diffusion hole. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] Sulfuric acid is an inorganic compound with the chemical formula H₂SO₄. It is the most important oxyacid of sulfur. Pure sulfuric acid is a colorless, oily liquid that crystallizes at 10.36°C. It is commonly produced using aqueous solutions of varying concentrations, using the tower process and the contact process. The former yields crude, dilute sulfuric acid, typically around 75% by mass; the latter yields concentrated sulfuric acid with a mass fraction of 98.3%, a boiling point of 338°C, and a relative density of 1.84.

[0024] This study summarizes the common active components of organophosphorus scale and corrosion inhibitors, including aminotris(methylenephosphonic acid) (ATMP), hydroxyethylidenediphosphonic acid (HEDP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMPA), and ethylenediaminetetramethylenephosphonic acid (EDTMPS). The study then comprehensively compares the physicochemical properties of organic polyphosphoric acids and inorganic sulfuric acid. The study found that when dried at 100-120°C, the organic polyphosphoric acids in the organophosphorus scale and corrosion inhibitors undergo coking and film formation, while the inorganic sulfuric acid remains fluid. This study leverages this property difference to design a unique test apparatus and streamlined analytical procedures, which are of great significance for the quality control and efficient and safe application of organophosphorus scale and corrosion inhibitors.

[0025] See also Figure 1 The present invention provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor. The core steps of the method include: Sample drying: Place the organophosphorus scale and corrosion inhibitor sample in a test device for drying to remove any moisture or other volatile substances. The drying temperature is usually between 100-120°C and the drying time is 4-8 hours.

[0026] Sample state observation: After drying, observe the physical state of the treated sample. If the treated sample shows a charred film state, it indicates that it is not contaminated with inorganic sulfuric acid. If the treated sample shows a charred film state and a fluid state, it indicates that the sample is contaminated with inorganic sulfuric acid.

[0027] Inorganic sulfuric acid volume measurement: When it is confirmed that the sample is contaminated with inorganic sulfuric acid, the volume of the inorganic sulfuric acid is further measured, and the flow state and volume of the flow state of the treated sample are obtained through the testing device; the flow state of the treated sample is diluted with water, the diluted flow state and volume of the diluted flow state are obtained, and the pH value of the diluted flow state is measured to calculate the volume percentage of inorganic sulfuric acid.

[0028] Specifically, it is achieved through the following steps: Obtain the flow state and volume of the flow state of the processed sample.

[0029] The flow state of the treated sample is diluted with water to obtain the volume of the diluted flow state and the diluted flow state (V2), the pH value of the diluted flow state is measured, the amount of water used in the diluted flow state is more than 100 times the volume of the flow state, and the volume percentage of inorganic sulfuric acid is calculated.

[0030] The volume percentage of inorganic sulfuric acid is calculated using a specific formula based on the pH, the volumes before and after dilution, and the density of inorganic sulfuric acid (usually 1.84 g / mL).

[0031] The above calculation formula: The volume percentage of inorganic sulfuric acid can be calculated by the following formula: 100%; in, is the volume percentage of inorganic sulfuric acid, 98 is the relative molecular mass of inorganic sulfuric acid, 1.84 is the density of inorganic sulfuric acid, pH is the pH value of the diluted flow state, V1 is the volume of the organophosphorus scale and corrosion inhibitor sample, and V2 is the volume of the diluted flow state.

[0032] In summary, the present invention distinguishes the sample status of the organophosphorus scale and corrosion inhibitor samples after high-temperature drying, and quickly, simply and accurately obtains the doping status of inorganic sulfuric acid, which can assist users in the actual situation of simple outdoor test conditions and short time when conducting product quality acceptance.

[0033] See also Figure 2 The present invention also provides a testing device for realizing the above-mentioned method of identifying inorganic sulfuric acid doped in organophosphorus scale and corrosion inhibitors, comprising a double-layer shell 1 and a containing cup 6 respectively composed of an inner layer and an outer layer, the shell 1 comprising a first part and a second part connected in an upper and lower section, a control and digital display 2 and an air inlet 3 being provided on the top surface of the first part, a blower 4 and a heating wire 5 being provided in sequence from top to bottom inside the first part; air diffusion holes 10 being provided on the bottom surface of the second part, a temperature sensor 7 being provided on the inner layer of the second part, an hourglass-shaped containing cup 6 being provided inside the second part, a first hole and a second hole being provided on the top surface and the side wall of the containing cup 6 respectively, a large plug 8 and a small plug 9 being provided on the first hole and the second hole respectively.

[0034] Furthermore, the holding cup 6 adopts an hourglass-shaped container with a concentric double-layer structure, and the holding cup 6 is composed of a symmetrical outer hourglass body and an asymmetrical inner hourglass body with a larger upper part and a smaller lower part; the outer hourglass body is a streamlined double-conical structure with a symmetrical upper and lower part, and the inner hourglass body is an asymmetric cone structure with a larger upper part and a smaller lower part; the outer hourglass body and the inner hourglass body constitute a measuring chamber, and the fluid connection between the upper and lower measuring chambers is achieved through the neck with equal diameter contraction in the middle section; the measuring chamber includes the upper cone chamber of section A and the lower cone chamber of section B; the volume ratio of the upper cone chamber of section A to the volume of the lower cone chamber of section B is greater than 100:1.

[0035] Furthermore, the inner hourglass body of the holding cup 6 is provided with a scale for accurately observing and measuring the volume of the internal substance.

[0036] Furthermore, the first hole and the second hole are opened on the top surface and side wall of the upper cone chamber of section A.

[0037] Furthermore, the inner layer of the first part extends relative to the outer layer of the first part to form an extended part, and the inner layer of the second part is retracted relative to the outer layer of the second part to form a retracted part, and the extended part and the retracted part are adapted to achieve a sealed connection.

[0038] In one embodiment, a testing device specifically for identifying whether inorganic sulfuric acid is doped in an organophosphorus scale and corrosion inhibitor is also provided. The device is composed of multiple key components, including: a shell 1, a control and digital display 2, an air inlet 3, a blower 4, a heating wire 5, a holding cup 6, a temperature sensor 7, a large plug 8, a small plug 9, and an air diffusion hole 10.

[0039] The shell 1 is double-layered, divided into two sections: the upper section (first section) has an extended inner layer, while the lower section (second section) has a recessed inner layer, ensuring a sealed connection between the upper and lower sections. The interior of the shell 1 is hollow, allowing for flexible access to the cup 6. The surface of the shell 1 is equipped with a control and digital display 2, an air inlet 3, and air diffusion holes 10. The control and digital display 2 is used to control the blower 4, heating wire 5, and temperature sensor 7; it also activates and deactivates the heating and air supply functions. The air inlet 3 and air diffusion holes 10 prevent the safety risk of excessive pressure in the enclosed space during heating. The blower 4, heating wire 5, and temperature sensor 7 are located within the shell 1 to maintain a continuous drying temperature of the organophosphorus scale and corrosion inhibitor sample between 100-120°C.

[0040] More specifically, the control and digital display 2 and the air inlet 3 are arranged on the top surface of the first part, the air blower 4 and the heating wire 5 are arranged inside the first part from top to bottom, the air diffusion hole 10 is opened on the bottom surface of the second part, the temperature sensor 7 is arranged on the inner layer of the second part, and the hourglass-shaped holding cup 6 is arranged inside the second part.

[0041] More specifically, the container 6 is an hourglass-shaped container with a concentric double-layered design, composed of a symmetrical outer hourglass body and an asymmetrical inner hourglass body with a larger upper portion and a smaller lower portion. The symmetrical outer hourglass body has a streamlined double-conical structure with symmetry, while the inner hourglass body is an asymmetrical frustum with a larger upper portion and a smaller lower portion. Fluid communication between the upper and lower chambers is achieved through a neck with a constant diameter contraction in the middle section. The measuring chamber is formed between the inner and outer layers. The volume of the upper cone chamber in section A is significantly larger than that of the lower cone chamber in section B. The volume ratio of the upper cone chamber in section A to the lower cone chamber in section B is greater than 100:1, creating a redundant overflow space to ensure that all possible outflowing substances and added pure water can be accommodated, while leaving sufficient space to prevent overflow.

[0042] The holding cup 6 has an overall hourglass-like structure, consisting of an inner and outer layer separated by a central neck. Specifically, the upper conical chamber of section A, located above the neck, constitutes the upper half of the holding cup 6. This double-layered structure creates a relatively large space suitable for holding a certain amount of material. The lower conical chamber of section B, located below the neck and forming the lower half of the holding cup 6, has a smaller space than section A.

[0043] A first hole and a second hole are formed on the top surface and the side wall of section A, and a large plug 8 and a small plug 9 are respectively arranged at the first hole and the second hole.

[0044] In this embodiment, the operating process of the method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor using the above-mentioned testing device is provided, which is specifically as follows: Close the small plug 9, open the large plug 8, load the organic phosphorus scale and corrosion inhibitor sample from the large plug 8 and obtain the volume V1 of the organic phosphorus scale and corrosion inhibitor sample, and the organic phosphorus scale and corrosion inhibitor flows into section B; place the holding cup 6 upright into the housing 1 and assemble the first and second parts; Turn on the control and digital display 2 to heat and dry; After drying, separate the first part and the second part, take out the holding cup 6, close the large stopper 8, invert the holding cup 6, and see if there is mobile phase flowing into section A; if so, read the volume of the mobile phase, open the small stopper 9, add pure water about 100 times the volume of the mobile phase for rinsing, and read the volume V2 of the diluted flow state.

[0045] In summary, the testing device of the present invention is reasonably designed and easy to operate, and can well meet the experimental requirements for identifying whether an organophosphorus scale and corrosion inhibitor is doped with inorganic sulfuric acid.

[0046] The present invention is described in further detail below with reference to the accompanying drawings: Example 1 This embodiment provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: Close the small stopper 9, open the large stopper 8, pour the No. 1 organophosphorus scale inhibitor and corrosion inhibitor sample into the holding cup 6, and record the volume of the No. 1 organophosphorus scale inhibitor and corrosion inhibitor sample V1 = 10 mL; Place the holding cup 6 containing the organic phosphorus scale and corrosion inhibitor sample in the housing 1, turn on the control and digital display 2 for heating and drying, and take out the holding cup 6 after drying at 120°C for 6 hours and let it stand to room temperature.

[0047] Visual observation of the sample revealed that only a charred film was formed, proving that the sample was not doped with inorganic sulfuric acid.

[0048] Example 2 This embodiment provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: Close the small stopper 9, open the large stopper 8, pour the No. 2 organophosphorus scale inhibitor and corrosion inhibitor sample into the holding cup 6, and record the volume of the No. 2 organophosphorus scale inhibitor and corrosion inhibitor sample V1 = 10 mL; Place the holding cup 6 containing the organic phosphorus scale and corrosion inhibitor sample in the housing 1, turn on the control and digital display 2 for heating and drying, and take out the holding cup 6 after drying at 120° C. for 4 hours and let it stand to room temperature.

[0049] Visual observation of the sample revealed that there was both a coked film and a fluidized state. The coexistence of the coked film and the fluidized state proved that the sample was doped with inorganic sulfuric acid.

[0050] Close the large stopper 8, invert the tube, and allow the mobile phase to flow into section A. Obtain the flow state and volume of the treated sample. The volume of the flowing flow state is approximately 2 ml. Open the small stopper 9, add pure water to section A for rinsing, obtain the dilution flow state, and record the volume of the dilution flow state V2 = 300 mL. Use pH test paper to measure the pH value of the diluted fluid state, pH=4.2.

[0051] Calculate the volume percentage of inorganic sulfuric acid: =10.08% Example 3 This embodiment provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: Close the small stopper 9, open the large stopper 8, pour the No. 3 organophosphorus scale inhibitor and corrosion inhibitor sample into the holding cup 6, and record the volume of the No. 3 organophosphorus scale inhibitor and corrosion inhibitor sample V1 = 20 mL; Place the holding cup 6 containing the organic phosphorus scale and corrosion inhibitor sample in the housing 1, turn on the control and digital display 2 for heating and drying, and take out the holding cup 6 after drying at 100° C. for 8 hours and let it stand to room temperature.

[0052] Visual observation of the sample revealed that there was both a coked film and a fluidized state. The coexistence of the coked film and the fluidized state proved that the sample was doped with inorganic sulfuric acid.

[0053] Close the large stopper 8, invert the tube, and allow the mobile phase to flow into section A. Obtain the flow state and volume of the treated sample. The volume of the flowing flow state is approximately 1 ml. Open the small stopper 9, add pure water to section A for rinsing, obtain the dilution flow state, and record the volume of the dilution flow state V2 = 100 mL. Use pH test paper to measure the pH value of the diluted fluid state, pH=5.4.

[0054] Calculate the volume percentage of inorganic sulfuric acid:

[0055] Example 4 This embodiment provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: Close the small stopper 9, open the large stopper 8, pour the No. 4 organophosphorus scale inhibitor and corrosion inhibitor sample into the holding cup 6, and record the volume of the No. 4 organophosphorus scale inhibitor and corrosion inhibitor sample V1 = 20 mL; Place the holding cup 6 containing the organic phosphorus scale and corrosion inhibitor sample in the housing 1, turn on the control and digital display 2 for heating and drying, and take out the holding cup 6 after drying at 120°C for 6 hours and let it stand to room temperature.

[0056] Visual observation of the sample revealed that there was both a coked film and a fluidized state. The coexistence of the coked film and the fluidized state proved that the sample was doped with inorganic sulfuric acid.

[0057] Close the large stopper 8, invert the tube, and allow the mobile phase to flow into section A. Obtain the flow state and volume of the treated sample. The volume of the flowing flow state is approximately 2 ml. Open the small stopper 9, add pure water to section A for rinsing, obtain the dilution flow state, and record the volume of the dilution flow state V2 = 300 mL. Use pH test paper to measure the pH value of the diluted fluid state, pH=3.8.

[0058] Calculate the volume percentage of inorganic sulfuric acid:

[0059] Example 5 This embodiment provides a method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, comprising the following steps: Close the small stopper 9, open the large stopper 8, pour the No. 5 organophosphorus scale inhibitor and corrosion inhibitor sample into the holding cup 6, and record the volume of the No. 5 organophosphorus scale inhibitor and corrosion inhibitor sample V1 = 20 mL; Place the holding cup 6 containing the organic phosphorus scale and corrosion inhibitor sample in the housing 1, turn on the control and digital display 2 for heating and drying, and take out the holding cup 6 after drying at 120° C. for 8 hours and let it stand to room temperature.

[0060] Visual observation of the sample revealed that there was both a coked film and a fluidized state. The coexistence of the coked film and the fluidized state proved that the sample was doped with inorganic sulfuric acid.

[0061] Close the large stopper 8, invert the tube, and allow the mobile phase to flow into section A. Obtain the flow state and volume of the treated sample. The volume of the flowing flow state is approximately 5 ml. Open the small stopper 9, add pure water to section A for rinsing, obtain the dilution flow state, and record the volume of the dilution flow state V2 = 500 mL. Use pH test paper to measure the pH value of the diluted fluid state, pH=4.9.

[0062] Calculate the volume percentage of inorganic sulfuric acid: 68% The present invention provides a method for identifying whether an organophosphorus scale and corrosion inhibitor is contaminated with inorganic sulfuric acid. A sample of the organophosphorus scale and corrosion inhibitor is placed in a testing device, dried, and then tested. If only a coked film forms, the sample is uncontaminated with inorganic sulfuric acid; if both a film and a fluidized state are present, the sample is contaminated with inorganic sulfuric acid. Subsequently, the pH value of the fluidized state is measured to calculate the volume fraction of inorganic sulfuric acid in the organophosphorus scale and corrosion inhibitor. This method is simple, rapid, highly operational, and highly accurate, and can be used for factory acceptance of organophosphorus scale and corrosion inhibitor products.

[0063] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor, characterized in that: The following steps are involved: S1: Place the organophosphorus scale and corrosion inhibitor sample into the test device for drying, and then obtain the treated sample; S2: Check the state of the treated sample to determine whether the organophosphorus scale and corrosion inhibitor sample is doped with inorganic sulfuric acid; if the treated sample shows both a coked film and a fluidized state, it is considered doped; S3: Obtain the flow state and volume of the treated sample; dilute the flow state of the treated sample with water, obtain the diluted flow state and volume of the diluted flow state, measure the pH value of the diluted flow state, and calculate the volume percentage of inorganic sulfuric acid.

2. The method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor according to claim 1, characterized in that: In S1, the drying process is carried out at a temperature of 100-120° C. for 4-8 hours.

3. The method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor according to claim 1, characterized in that: In S2, when the sample after treatment only showed a coked film state, it was determined that the organophosphorus scale and corrosion inhibitor was not doped with inorganic sulfuric acid.

4. The method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor according to claim 1, characterized in that: In S3, when the sample is diluted with water in a fluidized state, the amount of water used is more than 100 times the volume of the fluidized state.

5. The method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor according to claim 1, characterized in that: In S3, the formula for calculating the volume percentage of inorganic sulfuric acid is as follows: 100%； in, is the volume percentage of inorganic sulfuric acid, 98 is the relative molecular mass of inorganic sulfuric acid, 1.84 is the density of inorganic sulfuric acid, pH is the pH value of the diluted flow state, V1 is the volume of the organophosphorus scale and corrosion inhibitor sample, and V2 is the volume of the diluted flow state.

6. A testing device for realizing the method for identifying inorganic sulfuric acid doped in an organophosphorus scale and corrosion inhibitor according to any one of claims 1 to 5, characterized in that: The invention comprises a double-layer shell (1) consisting of an inner layer and an outer layer and a holding cup (6), wherein the shell (1) comprises a first part and a second part connected to each other in an upper and lower section, wherein a control and digital display (2) and an air inlet (3) are provided on the top surface of the first part, and a blower (4) and a heating wire (5) are provided in sequence from top to bottom inside the first part; an air diffusion hole (10) is provided on the bottom surface of the second part, a temperature sensor (7) is provided on the inner layer of the second part, and an hourglass-shaped holding cup (6) is provided inside the second part, wherein a first hole and a second hole are provided on the top surface and the side wall of the holding cup (6), respectively, and a large plug (8) and a small plug (9) are provided on the first hole and the second hole, respectively.

7. The testing device according to claim 6, characterized in that The holding cup (6) is an hourglass-shaped container with a concentric double-layer sleeve structure. The holding cup (6) is composed of a symmetrical outer hourglass body and an asymmetrical inner hourglass body with a larger upper portion and a smaller lower portion. The outer hourglass body is a streamlined double-cone structure with a symmetrical upper portion and a smaller lower portion, while the inner hourglass body is an asymmetrical frustum structure with a larger upper portion and a smaller lower portion.

8. The testing device according to claim 7, characterized in that: The outer hourglass body and the inner hourglass body constitute a measuring chamber, and fluid communication between the upper and lower measuring chambers is achieved through the neck with equal diameter contraction in the middle section; the measuring chamber includes an upper cone chamber in section A and a lower cone chamber in section B; the volume ratio of the upper cone chamber in section A to the lower cone chamber in section B is greater than 100:

1.

9. The testing device according to claim 7, characterized in that: The inner hourglass body of the holding cup (6) is provided with scales; the first hole and the second hole are opened on the top surface and the side wall of the upper cone chamber of section A.

10. The testing device according to claim 6, characterized in that: The inner layer of the first part extends relative to the outer layer of the first part to form an extended part, and the inner layer of the second part is retracted relative to the outer layer of the second part to form a retracted part. The extended part and the retracted part are adapted to achieve a sealed connection.

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