Method for analyzing biomass-to-methanol process pipe blockages

Abstract

The present application relates to the technical field of biomass gasification methanol production, and mainly relates to a biomass methanol production process pipeline blockage analysis method. The analysis method comprises the following steps: preliminarily determining the range of candidate substances of the blockage according to the appearance color of the blockage and the gas component of the biomass methanol production process; placing the blockage in an organic solvent, and performing first screening reduction on the range of candidate substances according to the dissolution state of the blockage; adding a dilute acid solution to the blockage, and performing second screening reduction on the range of candidate substances according to the dissolution state of the blockage in the dilute acid solution and the color change of the solution; placing the blockage in water and heating, and performing third screening reduction on the range of candidate substances according to the dissolution state of the blockage in the hot water and the color change of the solution; and determining that the blockage is ferrous ferricyanide according to the synthesis process conditions and the environment of the biomass methanol production.

Description

Technical Field

[0001] This invention relates to the field of biomass gasification to methanol technology, and mainly to a method for analyzing blockages in pipelines used in biomass methanol production processes. Background Technology

[0002] Biomass gasification to methanol is a key technological pathway, and its process mainly includes key steps such as biomass gasification to produce syngas, syngas purification, methanol synthesis, and distillation. Among these, syngas purification is crucial for ensuring the activity of the methanol synthesis catalyst and extending the operating cycle of the unit. However, in actual industrial operation, the syngas purification system frequently experiences pipeline blockage, severely hindering the continuous and stable operation of the unit.

[0003] Pipeline blockages are complex in composition, including not only conventional dust, carbides, and sulfides, but also special compounds formed by the reaction of trace impurities in syngas with the pipeline material or process medium. However, because the biomass gasification to methanol process involves multiple complex steps such as high-temperature gasification, syngas purification, and methanol synthesis, its preparation system simultaneously contains various components including iron-based pipeline materials, trace amounts of hydrogen cyanide, ammonia, and phenols, theoretically potentially generating a variety of dark-colored compounds.

[0004] Furthermore, the analysis of pipeline blockages in industrial settings has long been limited to qualitative analysis of elemental composition and physical characteristics, rarely delving into the identification of specific compounds. However, as pipeline blockages represent an anomaly in the process, analyzing the specific compounds within these blockages is of great significance for optimizing the biomass gasification to methanol production process. Summary of the Invention

[0005] The purpose of this invention is to provide an analytical method for pipeline blockages in biomass-to-methanol production processes, using ferrous ferrocyanide as the target component of the pipeline blockages and performing component analysis on the ferrous ferrocyanide in the pipeline blockages.

[0006] To address the above problems, the present invention provides an analytical method for clogging pipelines in a biomass-to-methanol process, the analytical method comprising: determining ferrous ferrocyanide as the target component of the clogging pipeline in the biomass-to-methanol process;

[0007] The specific steps for determining the target component of the pipeline blockage in the biomass-to-methanol process using ferrous ferrocyanide are as follows: Based on the appearance and color of the blockage and the gas-producing components of the biomass-to-methanol process, the range of candidate substances for the blockage is preliminarily determined; The blockage is placed in a non-alkaline organic solvent, and the range of candidate substances is narrowed down for the first time based on the dissolution state of the blockage. A dilute acid solution is added to the blockage, and the range of candidate substances is narrowed down a second time based on the dissolution state of the blockage in the dilute acid solution and the color change of the solution. The blockage is placed in water and heated. Based on the dissolution state of the blockage in hot water and the color change of the solution, the range of candidate substances is narrowed down for the third time. Based on the synthesis process conditions and environment for biomass-to-methanol production, the blockage material was determined to be ferrous ferrocyanide.

[0008] In one embodiment, the candidate substances include tetraamminecopper complex, ferricyanide complex, and indophenol blue.

[0009] In one embodiment, during the first screening and narrowing of the candidate material range, the blockage is insoluble in a non-alkaline organic solvent, thus excluding indophenol blue from the candidate material range.

[0010] In one embodiment, during the second screening and narrowing of the candidate material range, the blockage does not dissolve in a dilute acid solution, thus excluding tetraamminecopper complexes from the candidate materials.

[0011] In one embodiment, during the third screening and narrowing of the candidate material range, the blockage is insoluble in hot water, and the candidate material is ferrous ferrocyanide or ferric ferrocyanide in a ferric cyanide complex.

[0012] In one embodiment, after determining that ferrous ferrocyanide is the target component of the pipeline blockage in the biomass-to-methanol process, the method further includes the following step: taking the blockage for qualitative analysis to verify that the blockage contains ferrous ferrocyanide; The specific steps for qualitative analysis of the blockage are as follows: The blockage was placed in an organic solvent, and the dissolution state of the blockage was observed. The blockage was placed in a 0.5-1.0 mol / L dilute acid solution, and the dissolution state of the blockage and the color change of the hydrochloric acid solution were observed. The blockage was placed in an alkaline solution with a mass fraction of 5%-20% and heated to 80℃-90℃. The dissolution state of the blockage and the color change of the solution were observed. If the blockage does not dissolve in non-alkaline organic solvents or dilute acid solutions, and the acid solution does not show a color change; and the blockage decomposes in alkaline solutions, with the dark blue solid gradually fading into a brownish-red precipitate, then the blockage is determined to contain ferrous ferrocyanide.

[0013] In one embodiment, the non-alkaline organic solvent includes at least one of methanol, ethanol, and diethyl ether.

[0014] In one embodiment, the dilute acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid.

[0015] In one embodiment, the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide.

[0016] In one embodiment, before the step of taking the blockage for qualitative analysis, the following step is further included: drying the blockage to obtain dried blockage.

[0017] In one embodiment, after the step of taking the blockage for qualitative analysis, the method further includes the following step: purifying the dried blockage; The specific steps of the purification process are as follows: The blockage was treated with water, and the resulting precipitate was obtained by separation. The water-washed precipitate was soaked in dilute hydrochloric acid and heated to boiling, and then separated to obtain solid filter residue. The solid filter residue is washed with clean water until the pH of the washing solution is neutral. The washed solid filter residue was refluxed with anhydrous ethanol and then separated to obtain ferrous ferrocyanide solid.

[0018] In one embodiment, the concentration of the dilute hydrochloric acid is 0.5~1.0 mol / L.

[0019] In one embodiment, the water-washed precipitate is heated in dilute hydrochloric acid for 5 to 15 minutes.

[0020] In one embodiment, the reflux treatment with anhydrous ethanol is carried out for 20 min to 40 min.

[0021] In one embodiment, after the purification step of the dried blockage, the method further includes: The ferrous ferrocyanide solid and the filter paper to be used are dried. The content of the ferrocyanide solid was obtained by calculating the ratio of the ferrocyanide solid to the dried blockage by gravimetric method.

[0022] As can be seen from the above technical solution, the advantages and positive effects of this invention are as follows: In this application, based on the complex high-temperature working conditions of the multi-stage biomass gasification to methanol process, and the problem that the system simultaneously contains multiple easily reactive components such as iron-based pipe materials, hydrogen cyanide, ammonia, and phenols, easily generating various dark-colored by-products and difficult-to-identify mixed blockage components, in step S100, the candidate material range is first determined based on the appearance characteristics of the blockage and the gas production and medium composition of the process. Then, combined with the methanol synthesis process conditions and environmental mechanisms, ferrocyanide is determined as the target component of the blockage. Based on the generation source and reaction conditions of ferrocyanide, it is possible to transform the blockage into the target component of the specific compound ferrocyanide, breaking through the limitation of only being able to perform elemental composition and macroscopic phase qualitative analysis in industrial settings. Therefore, when similar blockages occur in the pipelines of biomass-to-methanol production processes, this analytical method can quickly and rigorously identify the target component of the blockage as ferrocyanide, clarify the source and reaction conditions of the blue blockage, and provide a more accurate basis for subsequent process pH control, reduction of HCN generation during gasification, equipment corrosion protection optimization, and adjustment of ammonia washing and steaming conditions. This effectively alleviates the problem of frequent blockages in syngas purification pipelines that seriously affect the continuous and stable operation of methanol plants, maintains the reliable operation of biomass-to-methanol synthesis processes, and extends the long-term continuous operation time of the units. Attached Figure Description

[0023] Figure 1 This is a flowchart of an analysis method for pipeline blockages in a biomass-to-methanol process according to an embodiment of the present invention; Figure 2 This is a diagram illustrating the specific steps involved in determining the target components of pipeline blockages in a biomass methanol production process using ferrous ferrocyanide as a biomass material, according to one embodiment of the present invention. Figure 3 This is a diagram illustrating the specific steps of taking the blockage for qualitative analysis and verifying that the blockage contains ferrous ferrocyanide in one embodiment of the present invention. Figure 4 This is a diagram illustrating the specific steps of purifying the dried blockage material in one embodiment of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0025] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0026] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0027] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0028] Pipeline blockages are complex in composition, including not only conventional dust, carbides, and sulfides, but also special compounds formed by the reaction of trace impurities in syngas with the pipeline material or process medium. However, because the biomass gasification to methanol process involves multiple complex steps such as high-temperature gasification, syngas purification, and methanol synthesis, its preparation system simultaneously contains various components including iron-based pipeline materials, trace amounts of hydrogen cyanide, ammonia, and phenols, theoretically potentially generating a variety of dark-colored compounds.

[0029] Furthermore, the analysis of pipeline blockages in industrial settings has long been limited to qualitative analysis of elemental composition and physical characteristics, rarely delving into the identification of specific compounds. However, as pipeline blockages represent an anomaly in the process, analyzing the specific compounds within these blockages is of great significance for optimizing the biomass gasification to methanol production process.

[0030] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: Figure 1 This is a flowchart of an analysis method for pipeline blockages in a biomass-to-methanol process according to an embodiment of the present invention; Figure 2 This is a diagram illustrating the specific steps involved in determining the target components of pipeline blockages in a process for preparing methanol from biomass using ferrocyanide as a biomass, according to one embodiment of the present invention.

[0031] like Figure 1 and Figure 2 As shown, one aspect of the present invention provides a method for analyzing blockages in pipelines used in biomass-to-methanol production processes. The method includes: S100. Determine the target components of pipeline blockages in the process of preparing methanol from biomass using ferrous ferrocyanide.

[0032] The specific steps for determining the target component of pipeline blockages in the process of preparing methanol from biomass using ferrous ferrocyanide are as follows: S110. Based on the appearance and color of the blockage and the gas-producing components of the biomass-to-methanol process, the range of candidate substances for the blockage is preliminarily determined. Candidate substances include tetraamminecopper complex, ferricyanide complex, and indophenol blue.

[0033] In step S110, based on the dark blue solid appearance of the pipe blockage and in conjunction with the actual gas production and material composition of the biomass methanol production process, the range of candidate substances for the blockage is preliminarily determined.

[0034] Specifically, the gas produced by high-temperature biomass gasification contains components such as ammonia, hydrogen cyanide, and phenols. Iron corrosion ions (Fe²⁺) will be generated in the carbon steel equipment and pipelines of the process system. + or Fe³ + Furthermore, considering the process conditions where no copper sulfate raw material is added and no copper sulfate is generated throughout the entire process, copper sulfate is directly excluded. Then, based on the types of blue substances that can be generated by the process components, the candidate substances are initially classified into three categories: tetraamminecopper complex, ferricyanide complex, and indophenol blue generated by phenol-amine condensation.

[0035] S120. Place the blockage material in an organic solvent and, based on the dissolution state of the blockage material, perform the first screening to narrow down the range of candidate substances.

[0036] In the first screening and narrowing of the candidate material range, if the blockage does not dissolve in a non-alkaline organic solvent, indophenol blue is excluded from the candidate material list.

[0037] Specifically, in step S120, non-alkaline organic solvents such as alcohols and ethers, specifically ethanol, methanol, dimethyl ether, diethyl ether, etc., can be selected as identification solvents, and the blockage is placed in the organic solvent and left to stand for observation.

[0038] Because indophenol blue is an organic conjugated dye, it is readily soluble in organic solvents such as alcohols and ethers. If the precipitate is indophenol blue, it will dissolve as a solid, and the organic solvent will be dyed blue. Ferric cyanide complexes and tetraamminecopper complexes, on the other hand, are insoluble in common non-alkaline organic solvents.

[0039] This blockage does not dissolve in non-alkaline organic solvents and does not show any color change in the solution, thus excluding indophenol blue. The candidate substances are narrowed down for the first time to tetraamminecopper complex and ferricyanide complex.

[0040] S130. Add a dilute acid solution to the blockage. Based on the dissolution state of the blockage in the dilute acid solution and the color change of the solution, a second screening is conducted to narrow down the candidate substances. In this second screening step, if the blockage does not dissolve in the dilute acid solution, tetraamminecopper complex is excluded as a candidate substance.

[0041] Specifically, the dilute acid solution can be a non-oxidizing dilute acid such as dilute hydrochloric acid, dilute sulfuric acid, or dilute phosphoric acid. The dilute acid solution is added dropwise to the blockage system, and the dissolution state of the blockage and the color change of the solution are observed after standing at room temperature.

[0042] Because the coordination bonds of the tetraamminecopper complex are unstable, it easily breaks down and dissociates in the presence of acid, causing the blue color of the solid to fade rapidly, the solution to change color, and a flocculent precipitate of copper salt to form. However, the ferricyanide complex is resistant to dilute weak acids; it does not dissolve or decompose in dilute acids, the blue color does not fade, and the solution does not show obvious color changes.

[0043] In this step, the solid of the blockage was stable after adding dilute acid and the solution color did not change, thus eliminating the tetraamminecopper complex. The candidate substances were narrowed down for the second time, leaving only the ferricyanide complex.

[0044] S140. The blockage is placed in water and heated. Based on the dissolution state of the blockage in hot water and the color change of the solution, the range of candidate substances is narrowed down for the third time. In the third screening step of narrowing down the range of candidate substances, if the blockage does not dissolve in hot water, the candidate substance is ferrous ferrocyanide or ferric ferricyanide in the ferricyanide complex.

[0045] Specifically, the blockage is placed in pure water, heated to 80℃~90℃, and then observed at a constant temperature.

[0046] Ferric cyanide complexes generally include ferrocyanide and ferric cyanide. Among them, alkali metal salts such as potassium ferrocyanide, sodium ferrocyanide, potassium ferric cyanide, and sodium ferric cyanide are soluble salts and are easily soluble in hot water, but ferrous ferrocyanide and ferric ferric cyanide are insoluble in hot water.

[0047] In this step, the blockage did not dissolve and the solution showed no obvious color change, thus further confirming that the ferricyanide complex was ferrous ferrocyanide and ferric ferricyanide. In this step, the blockage showed no visible change in morphology or color after heating; the difference in thermal stability was used to complete the third screening, eliminating heat-sensitive and easily hydrolyzed blue interfering substances.

[0048] S150. Based on the synthesis process conditions and environment for biomass-to-methanol production, the blockage material is determined to be ferrocyanide.

[0049] In the biomass-to-methanol synthesis process, the gas produced by high-temperature biomass gasification contains hydrogen cyanide (HCN) and ammonia (NH3). HCN provides cyanide ions, and production equipment such as carbon steel ammonia washing towers and pipelines can continuously release Fe²⁺ during corrosion. + and Fe³ + The process involves ammonia to create a weakly alkaline environment, which in turn provides the raw material basis for the formation of ferrocyanide.

[0050] Specifically, maintaining the pH in the ammonia washing and stripping system within a weakly alkaline range of 8-10 provides the optimal acid-base environment for ferrocyanide coordination, leading to the formation of ferric ferrocyanide precipitate. Furthermore, the ammonia washing absorption, ammonia stripping heating, and circulating liquid concentration processes further promote ion coordination, supersaturation, and the precipitation of deep blue microcrystalline precipitates, resulting in pipeline blockage. Therefore, considering the synthesis process conditions and environment for biomass-to-methanol production, the process system exhibits a characteristic reaction where cyanide coordinates with ferrous iron to form ferrocyanide, which then complexes with ferric iron to precipitate ferric ferrocyanide. This aligns with the experimental phenomena observed in the screening process used to determine ferric ferrocyanide as the target component for pipeline blockage in the biomass-to-methanol production process. Ultimately, ferric ferrocyanide was identified as the target component for the blue blockage in the biomass-to-methanol production process pipeline.

[0051] In this application, based on the complex high-temperature operating conditions of the biomass gasification to methanol process, and the challenges posed by the simultaneous coexistence of various reactive components such as iron-based pipeline materials, hydrogen cyanide, ammonia, and phenols, which easily generate various dark-colored byproducts and make the blockage components difficult to identify, step S100 first determines the range of candidate substances based on the appearance characteristics of the blockage and the composition of the gas produced and the medium in the process. Then, based on the methanol synthesis process conditions and environmental mechanisms, ferric ferrocyanide is determined as the target component of the blockage. According to the formation source and reaction conditions of ferric ferrocyanide, it is possible to transform the blockage into a specific compound, ferric ferrocyanide, as the target component of the blockage, thus overcoming the limitations of only being able to perform elemental composition and macroscopic phase identification in industrial settings. Therefore, when similar blockages occur in the pipelines of biomass-to-methanol production processes, this analytical method can quickly and rigorously identify the target component of the blockage as ferrocyanide, clarify the source and reaction conditions of the blue blockage, and provide a more accurate basis for subsequent process pH control, reduction of HCN generation during gasification, equipment corrosion protection optimization, and adjustment of ammonia washing and steaming conditions. This effectively alleviates the problem of frequent blockages in syngas purification pipelines that seriously affect the continuous and stable operation of methanol plants, maintains the reliable operation of biomass-to-methanol synthesis processes, and extends the long-term continuous operation time of the units.

[0052] like Figure 1As shown, in some embodiments, before the step of taking the blockage material for qualitative analysis, the following step is further included: S200, drying the blockage material to obtain dried blockage material. Specifically, the blockage material is placed in an oven and dried at 100℃~110℃ for 0.5~1.5 hours until constant weight.

[0053] In this step, the original blockage sample is first dried and pretreated. By drying the blockage, the free water and process liquid residue adsorbed on the surface of the blockage are removed, and the interference of water on subsequent tests is eliminated, so as to obtain a dried blockage sample with stable moisture content. The dried blockage is then used in subsequent qualitative tests and purification.

[0054] Among them, since the pipe blockages collected at the process site mostly adsorb the liquid phase of the washing and steaming ammonia process, free water and soluble salt impurities, if the dissolution, acid leaching and hot alkali test are carried out directly, the residual water will dilute the concentration of organic solvent, acid solution and alkali solution, and will also introduce soluble ions to interfere with the observation of dissolution state and color change; pre-drying can remove free water and liquid phase residue, and avoid misjudgment caused by moisture.

[0055] Figure 3 This is a diagram illustrating the specific steps involved in a specific embodiment of the present invention to perform qualitative analysis on the blockage and verify that the blockage contains ferrous ferrocyanide.

[0056] like Figure 1 and Figure 3 As shown, in some embodiments, after determining the target component of the pipeline blockage in the biomass-to-methanol process using ferrous ferrocyanide, the following steps are also included: S300. Take the blockage material for qualitative analysis to verify that the blockage material contains ferrous ferrocyanide.

[0057] The specific steps for qualitative analysis of the blockage are as follows: S310. Place the blockage material in an organic solvent and observe its dissolution state. Specifically, the organic solvent includes at least one of methanol, ethanol, and diethyl ether.

[0058] S320. Place the blockage in a 0.5~1.0 mol / L dilute acid solution and observe the dissolution state of the blockage and the color change of the dilute acid solution.

[0059] The dilute acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid. A non-oxidizing dilute acid solution, such as dilute hydrochloric acid, is selected. The blockage sample is placed in the dilute acid system and allowed to stand at room temperature to observe the dissolution state of the blockage and the color change of the hydrochloric acid solution.

[0060] S330, Place the blockage in a solution with a mass fraction of 5%-20%. alkaline solutionThe solution is heated to 80℃~90℃, and the dissolution state of the blockage and the color change of the solution are observed. The alkaline solution includes at least one of sodium hydroxide and potassium hydroxide.

[0061] S340. If the blockage does not dissolve in non-alkaline organic solvents or dilute acid solutions, and the acid solution does not show a color change; and the blockage decomposes in alkaline solutions, with the dark blue solid gradually fading into a brownish-red precipitate, then the blockage is determined to contain ferrous ferrocyanide.

[0062] Among them, since ferrocyanide is an inorganic ferricyanide coordination crystal, it is insoluble in alcohols such as ethanol and ethers, which are common non-alkaline organic solvents, at room temperature; if the sample does not dissolve in non-alkaline organic solvents, does not dissolve, and does not turn the organic solvent blue in the S310 test, it not only eliminates organic blue impurities such as indophenol blue that are easily soluble in organic solvents, but also conforms to the inherent dissolution characteristics of ferrocyanide, thus completing the first verification judgment.

[0063] Furthermore, ferrocyanide exhibits resistance to dilute acids; it does not dissolve or decompose in dilute acids, its blue color does not fade, and it does not cause significant color changes in acid solutions. Meanwhile, tetraamminecopper complexes easily break down and fade in dilute acids, and organic impurities readily decompose and develop color in acidic environments. If, in the S320 step test, the blockage remains in a solid state and does not dissolve in dilute acid solution, its blue color does not fade, and the acid solution shows no significant color change, this conforms to the stable dilute acid resistance characteristics of ferrocyanide, further eliminating copper-ammonia complexes and completing the second verification judgment.

[0064] Then, prepare a sodium hydroxide or potassium hydroxide solution, place the blockage sample in the alkaline solution, and maintain the temperature in a water bath at a constant 80℃~90℃ for observation. Under high temperature and concentrated alkaline conditions, the coordination structure of ferrocyanide is destroyed, and the dissociated iron ions react with hydroxide ions to form a yellowish-brown flocculent ferric hydroxide. The ferrocyanide ions dissolve in the alkaline solution, and the blue blockage can be observed to gradually dissolve, with the overall solution system turning yellowish-brown. That is, in step S230, the blockage gradually dissolves and breaks down in the hot alkaline system, and the solution color gradually fades from the initial blue to brownish-red, which conforms to the characteristic reaction behavior of ferrocyanide when exposed to heated concentrated alkaline solution, completing the third characteristic verification.

[0065] Because the biomass gasification to methanol system has a complex composition and can generate a variety of blue and dark-colored compounds, in step S300 of this invention, the composition of the blockage is determined by a combination of the characteristics of organic solvent solubility, dilute acid stability, and thermal concentrated alkali decomposition. This avoids the defects of misjudgment by a single test, effectively distinguishes indophenol blue, tetraamminecopper complex and ferric ferrocyanide, and achieves accurate qualitative identification of the blockage at the compound level. This makes up for the shortcomings of traditional analysis, which only performs elemental and physical analysis and cannot determine the specific compounds.

[0066] On the other hand, existing technologies typically employ complex instrumental analysis methods such as thermogravimetric analysis, thermal pyrolysis gas chromatography-mass spectrometry, organic solvent extraction, and stepwise extraction to analyze abnormal substances such as precipitates and blockages generated during complex production processes. These methods suffer from drawbacks including high equipment investment, complex experimental procedures, long detection cycles, high analytical costs, and difficulty in adapting to rapid source tracing and investigation in industrial settings. This application first identifies the target components of blockages in pipelines used in the biomass-to-methanol production process using ferric ferrocyanide in step S100. Then, in step S300, the blockage is collected for qualitative analysis to verify that it contains ferric ferrocyanide. The qualitative verification primarily utilizes chemical qualitative verification steps based on differences in the physicochemical properties of the substances. Only conventional non-alkaline organic solvents, dilute acids, and ordinary alkaline solutions are used, along with conventional water bath heating at 80–90°C, to complete the qualitative test. This eliminates the need for large-scale precision analytical instruments; detection and determination can be achieved using only basic laboratory glassware and reagents. Furthermore, it significantly reduces the reliance on specialized high-end analytical equipment for the qualitative analysis of blockage compounds, simplifies the experimental procedures, lowers the professional operation threshold, and reduces the maintenance costs of testing materials and equipment. Simultaneously, the experimental steps are simple and intuitive, omitting complex pretreatment and instrument calibration processes. This makes it more suitable for rapid sampling in industrial settings during biomass-to-methanol production, enabling rapid qualitative analysis and fault tracing, thus addressing the technical pain points of traditional instrumental analysis methods, such as high cost, cumbersome operation, and inconvenience for on-site application. While simplifying testing conditions and reducing costs, it still ensures the accuracy and rigor of ferrocyanide qualitative results, balancing testing economy, convenience, and reliability.

[0067] Figure 4 This is a diagram illustrating the specific steps of purifying the dried blockage material in one embodiment of the present invention.

[0068] like Figure 1 and Figure 4 As shown, in some embodiments, after the step of taking the blockage for qualitative analysis, the following step is further included: S400, purifying the dried blockage.

[0069] The specific steps of the purification process are as follows: S410. Add water to the blockage and separate it to obtain a water-washed precipitate; repeat the step of adding water to the blockage 2 to 4 times.

[0070] Specifically, after drying the blockage, add pure water and thoroughly stir and soak or rinse it. This allows water-soluble salt impurities, such as inorganic salts and other process-soluble ionic impurities, to dissolve fully in the water. Then, by allowing it to settle, the density difference is used to separate dust impurities, thus removing water-soluble impurities and suspended fine dust. The water-insoluble solid phase is collected to obtain a washed precipitate. Repeating this water treatment 2-4 times can more effectively remove soluble components trapped in the pores of the blockage, as well as water-soluble salts and some dust.

[0071] S420. The water-washed precipitate is soaked in dilute hydrochloric acid and heated to boiling, and then separated to obtain solid filter residue. The concentration of dilute hydrochloric acid is 0.5~1.0 mol / L, and the heating time of the water-washed precipitate in dilute hydrochloric acid is 5 min~15 min.

[0072] Specifically, by soaking the water-washed precipitate in a dilute hydrochloric acid system and heating it to boiling, the high-temperature conditions of the acid solution can be used to dissolve, decompose, and wash away acid-soluble interfering complexes such as metal oxides, basic salts, carbonates, and sulfides in the blockage, specifically Fe(OH)3, Fe... 2+ It contains impurities such as carbonates, ammonium salts, and metals. Ferrous ferrocyanide remains stable and insoluble even under dilute acid boiling conditions; further solid-liquid separation removes acid-soluble impurities, yielding a solid filter residue with further improved purification.

[0073] S430. Wash the solid filter residue with clean water until the pH value of the washing solution is neutral.

[0074] In step S430, the solid filter residue is repeatedly rinsed and soaked with clean water to gradually remove residual hydrochloric acid, acidic ions, and dissolved impurities adsorbed on the surface of the filter residue. Washing continues until the pH of the final washing solution is neutral to avoid the influence of residual acid on subsequent processing and product purity.

[0075] S440. The washed solid filter residue is refluxed with anhydrous ethanol and then separated to obtain ferrocyanide solid. The reflux time with anhydrous ethanol is 20 min to 40 min.

[0076] Specifically, after anhydrous ethanol is refluxed, a vacuum filtration device can be used for solid-liquid separation, and the separated solids can be washed with anhydrous ethanol.

[0077] In step S440, the neutralized and washed solid filter residue is refluxed with anhydrous ethanol. The ethanol dissolves residual organic impurities, resinous substances, phenolic derivatives and water in the sample, while ethanol does not dissolve ferrocyanide. After reflux, solid-liquid separation is performed to remove organic impurities and residual water, and finally high-purity ferrocyanide solid is obtained.

[0078] Because the blockages in biomass methanol pipelines are composed of a variety of substances, including dust, carbides, sulfides, soluble inorganic salts, water-soluble ferricyanides, metal oxides, and phenolic organic impurities, this invention addresses this issue by using 2-4 repeated water washings to preferentially remove water-soluble impurities and dust during the purification process of the dried blockages. Next, dilute hydrochloric acid is used to selectively dissolve carbonates, metal oxides, and acid-soluble complexes. Neutralization with clean water eliminates residual acid interference. Finally, anhydrous ethanol is refluxed to remove phenolic derivatives and organic impurities. This step-by-step and precise removal of multiple types of impurities effectively purifies the product to obtain high-purity ferrocyanide solid. Without damaging the structure of ferrocyanide, the purity of the purified product is significantly improved, effectively yielding high-purity ferrocyanide solid.

[0079] In contrast, existing technologies for analyzing similar blockages in processes generally employ thermogravimetric analysis, thermal pyrolysis and gas chromatography-mass spectrometry, complex organic solvent extraction, and multi-step reagent extraction. These methods suffer from high equipment investment, cumbersome procedures, and expensive testing costs, making them difficult for ordinary laboratories to equip and unsuitable for routine field applications. In this invention, the purification step for ferrocyanide blockages uses conventional reagents such as pure water, dilute hydrochloric acid, and anhydrous ethanol. Purification can be completed using conventional laboratory equipment such as soaking, heating and boiling, filtration, washing, and reflux. No large-scale precision analytical instruments are required, the operation is simple and controllable, and the testing cost is low, making it more suitable for the practical needs of rapid screening in industrial settings and widespread application in routine laboratories.

[0080] Furthermore, ferrocyanide is a key biomarker reflecting the HCN production in the gasifier and the cyanide removal efficiency of the syngas purification system. The efficient and targeted purification of blockages achieved through the above steps facilitates further quantitative content detection. The purified high-purity ferrocyanide sample provides a pure sample and data foundation for reverse engineering the nitrogen component conversion patterns in the gasifier, optimizing gasification conditions, and adjusting key parameters such as the amount of ammonia absorbent used in washing and steaming, reaction temperature, and gas-liquid ratio. This effectively solves problems such as production shutdowns due to blockages in the biomass-to-methanol process.

[0081] In some embodiments, after the purification step of the dried blockage, the method further includes: S500: Dry the ferrous ferrocyanide solid and the filter paper to be used.

[0082] Specifically, the purified ferrous ferrocyanide solid and the filter paper to be used in the experiment can be placed in a drying equipment for constant temperature drying to completely remove the free water, ethanol residue and other substances adsorbed in the solid and filter paper. After cooling to room temperature, it can be used for future reference to ensure that the weighing standard is dry and constant.

[0083] S600. Calculate the ratio of ferrocyanide solids to dried blockage material using the gravimetric method to obtain the content of ferrocyanide solids.

[0084] Specifically, the mass of the dried blank filter paper and the total mass of the filter paper carrying the ferrocyanide solid were weighed separately, and the difference was calculated to obtain the oven-dry mass of the purified ferrocyanide solid. Then, this mass was compared with the mass of the initially dried blockage sample to quantitatively determine the mass percentage of ferrocyanide in the pipeline blockage. This quantitative determination of the actual ferrocyanide content in the blockage allows for a more intuitive assessment of the degree of byproduct formation and blockage severity in the ammonia washing and steaming section and the syngas purification section. It also facilitates quantitative comparison of changes in formation under different operating conditions, pH levels, and gasification conditions, providing quantitative data support for precise control of process parameters, suppression of byproduct formation, alleviation of pipeline blockage, and ensuring long-term stable operation of the unit.

[0085] In the analysis of blockages in actual biomass-to-methanol production pipelines, purified ferrocyanide solids accounted for as much as 30-40% of the blockages. This demonstrates that the amount of ferrocyanide generated largely determines the degree of pipeline blockage and the operating load of the equipment. This invention rapidly and qualitatively identifies ferrocyanide as the target component of the blockage and determines its proportion in the blockage through purification. This provides a key solution for addressing the root cause of the problem in subsequent process condition control, enabling more accurate and targeted adjustments to the process.

[0086] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of this application is limited only by the appended claims.

Claims

1. A method for analyzing pipeline blockages in a biomass-to-methanol process, characterized in that, The analytical method includes: identifying the target component of the pipeline blockage in the biomass-to-methanol process using ferriferric ferrocyanide; The specific steps for determining the target component of the pipeline blockage in the biomass-to-methanol process using ferrous ferrocyanide are as follows: Based on the dark blue solid appearance of the blockage and the gas-producing components of the biomass-to-methanol process, the range of candidate substances for the blockage is preliminarily determined; the candidate substances include tetraamminecopper complex, ferricyanide complex, and indophenol blue; The blockage is placed in a non-alkaline organic solvent, and the candidate substances are narrowed down for the first time based on the dissolution state of the blockage and the color change of the solution. The non-alkaline organic solvent includes ethanol, methanol, dimethyl ether, or diethyl ether. In the first screening and narrowing down of the candidate substances, if the blockage does not dissolve in the non-alkaline organic solvent and the solution does not show obvious color change, indophenol blue is excluded from the candidate substances. A dilute acid solution is added to the blockage. Based on the dissolution state of the blockage in the dilute acid solution and the color change of the solution, a second screening is performed to narrow down the candidate substances. The dilute acid includes dilute hydrochloric acid, dilute sulfuric acid, or dilute phosphoric acid. In the second screening step of narrowing down the candidate substances, if the blockage does not dissolve in the dilute acid solution and the solution color does not change, the candidate substances are excluded from the tetraamminecopper complex. The blockage is placed in water and heated. Based on the dissolution state of the blockage in hot water and the color change of the solution, the range of candidate substances is narrowed down for the third time. This includes placing the blockage in pure water, heating it to 80℃~90℃, and then observing it at a constant temperature. If the blockage does not dissolve in hot water and the solution does not show obvious color change, the candidate substance is ferrous ferrocyanide or ferric ferrocyanide in the ferric cyanide complex. Based on the synthesis process conditions and environment for biomass-to-methanol production, the blockage was determined to be ferrocyanide. In the biomass-to-methanol synthesis process, the gas produced by high-temperature biomass gasification contains hydrogen cyanide and ammonia. Hydrogen cyanide provides cyanide ions, and the carbon steel ammonia washing tower and pipelines continuously release Fe during corrosion. 2+ and Fe 3+ During the process, ammonia forms a weakly alkaline environment, which satisfies the raw material requirements for the formation of ferrocyanide. The pH of the ammonia washing and steaming system is maintained in the weakly alkaline range of 8 to 10. The ammonia washing and absorption, ammonia steaming and heating, and circulating liquid concentration will further promote ion coordination and supersaturation to precipitate deep blue microcrystalline precipitates. Combined with the synthesis process conditions and environment of biomass to prepare methanol, the process system can undergo the characteristic reaction of cyanide ions coordinating with ferrous iron to form ferrocyanide ions, which then complex with ferric iron to precipitate ferrocyanide.

2. The method for analyzing pipeline blockages in biomass-to-methanol production processes according to claim 1, characterized in that, After determining that ferrous ferrocyanide is the target component of the pipeline blockage in the biomass methanol production process, the method further includes the following steps: taking the blockage for qualitative analysis to verify that the blockage contains ferrous ferrocyanide; The specific steps for qualitative analysis of the blockage are as follows: The blockage was placed in a non-alkaline organic solvent, and the dissolution state of the blockage was observed. The blockage was placed in a 0.5~1.0 mol / L dilute acid solution, and the dissolution state of the blockage and the color change of the dilute acid solution were observed. The blockage was placed in an alkaline solution with a mass fraction of 5%-20% and heated to 80℃-90℃. The dissolution state of the blockage and the color change of the solution were observed. If the blockage does not dissolve in non-alkaline organic solvents or acidic solutions, and no obvious color change occurs in the acidic solution; and the blockage decomposes in alkaline solutions, with the dark blue solid gradually fading into a brownish-red precipitate, then the blockage is determined to contain ferrous ferrocyanide.

3. The method for analyzing pipeline blockages in biomass-to-methanol production processes according to claim 2, characterized in that, In the specific steps of qualitative analysis of the blockage, the non-alkaline organic solvent includes at least one of methanol, ethanol, and diethyl ether.

4. The method for analyzing pipeline blockages in biomass-to-methanol production processes according to claim 2, characterized in that, In the specific steps of qualitative analysis of the blockage, the dilute acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid; and / or In the specific steps of qualitative analysis of the blockage, the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide.

5. The method for analyzing pipeline blockages in a biomass-to-methanol process according to claim 2, characterized in that, Before the step of taking the blockage for qualitative analysis, the following step is also included: drying the blockage to obtain dried blockage.

6. The method for analyzing pipeline blockages in a biomass-to-methanol process according to claim 5, characterized in that, After the step of taking the blockage for qualitative analysis, the method further includes the following step: purifying the dried blockage; The specific steps of the purification process are as follows: The blockage was treated with water, and the resulting precipitate was obtained by separation. The water-washed precipitate was soaked in dilute hydrochloric acid and heated to boiling, and then separated to obtain solid filter residue. The solid filter residue is washed with clean water until the pH of the washing solution is neutral. The washed solid filter residue was refluxed with anhydrous ethanol and then separated to obtain ferrous ferrocyanide solid.

7. The method for analyzing pipeline blockages in a biomass-to-methanol process according to claim 6, characterized in that, The concentration of the dilute hydrochloric acid is 0.5 mol / L to 1.0 mol / L; and / or The water-washed precipitate is heated in dilute hydrochloric acid for 5 to 15 minutes; and / or The reflux treatment time using anhydrous ethanol is 20 min to 40 min.

8. The method for analyzing pipeline blockages in a biomass-to-methanol process according to claim 6, characterized in that, After the step of purifying the dried blockage, the method further includes: The ferrous ferrocyanide solid and the filter paper to be used are dried. The content of the ferrocyanide solid was obtained by calculating the ratio of the ferrocyanide solid to the dried blockage by gravimetric method.

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