Method for preparing pyroligneous liquor and phenolic compounds from walnut shells

Abstract

The invention provides a method for preparing pyroligneous liquor and phenolic compounds from walnut shells. The method comprises the following steps: putting a certain amount of walnut shell particles into a stock bin; a small amount of walnut shell particles are added into a thermal cracking reactor for thermal cracking, and generated cracking gas exhausts air in the reactor; adding the residual walnut shell particles into a reactor for thermal cracking; generated pyrolysis gas enters a dust remover for purification and dust removal; the obtained residual carbon flue gas enters a recovery heater, and the obtained pure cracking gas enters a condenser for condensation; condensed liquid obtained through condensation is fed into a liquid receiving tank to be stored; wood vinegar on the upper layer and biomass oil on the lower layer are separated from the liquid receiving tank and are weighed respectively; and extracting the pyroligneous liquor by using an extracting agent to obtain the phenolic compound. The method for preparing the pyroligneous liquor and the phenolic compounds from the walnut shells is simple in process, and the yield and the purity of the pyroligneous liquor and the phenolic compounds can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of wood vinegar preparation, and in particular to a method for preparing wood vinegar and phenolic compounds by utilizing walnut shells. Background Art

[0002] The traditional preparation process of wood vinegar usually relies on fossil fuels, which consumes a lot of energy and can cause environmental pollution. With the rapid development of green chemistry and the increasing emphasis on sustainable resource management, researchers have explored the use of biomass waste, such as walnut shells, straw, sawdust, etc., as pyrolysis raw materials to extract wood vinegar and phenolic compounds.

[0003] Among them, walnut shell thermal cracking as a method of resource recovery and waste utilization has attracted widespread attention from researchers. Currently, some studies have explored the decomposition of walnut shells under high temperature conditions to release potential acetic acid through thermal cracking technology.

[0004] However, how to effectively control the reaction conditions (such as temperature, pressure and residence time) to maximize the efficiency of acetic acid extraction remains a major challenge, while also reducing by-product generation and energy consumption. Currently, the preparation of wood vinegar by high-temperature pyrolysis of walnut shells has many limitations, including low energy efficiency, insufficient product purity, and high by-product processing costs. In addition, under unoptimized conditions, the content of phenolic compounds in wood vinegar is low and there are more impurities, which limits its application benefits in actual production.

[0005] Therefore, it is necessary to improve the yield and purity of wood vinegar and phenolic compounds by optimizing the thermal cracking process parameters of walnut shells, such as accurately controlling the cracking temperature, increasing the heating rate and optimizing the gas phase residence time. Summary of the invention

[0006] The technical problem to be solved by the invention is to provide a preparation process method which uses walnut shell as a raw material and can significantly improve the yield and purity of wood vinegar and phenolic compounds.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing wood vinegar and phenolic compounds using walnut shells, comprising the following steps:

[0008] Drying and crushing the walnut shells to obtain walnut shell particles;

[0009] A certain amount of walnut shell particles is placed in a silo, and the silo is connected to a thermal cracking reactor pipeline;

[0010] The pyrolysis reactor is initially heated to 200-350° C., 20-25% of walnut shell particles are added to the pyrolysis reactor through a silo, and the air in the pyrolysis reactor is exhausted by the generated pyrolysis gas;

[0011] The thermal cracking reactor is connected with the dust collector, the condenser and the liquid receiving tank in sequence through pipelines;

[0012] The remaining walnut shell particles in the silo were added to the thermal cracking reactor and heated at 10 4 ~10 5 The thermal cracking reactor is heated again to 400-600°C at a heating rate of K / s to carry out thermal cracking reaction;

[0013] The generated cracking gas stays in the thermal cracking reactor for no more than 2 seconds before entering the dust collector for purification and dust removal;

[0014] The residual carbon flue gas obtained by purification and dust removal enters the recovery heater, and the obtained pure cracking gas enters the condenser with a temperature of 20-25°C for condensation, and the residual carbon flue gas obtained by purification and dust removal enters the recovery heater;

[0015] The condensate obtained by condensation is sent to a liquid receiving tank for storage;

[0016] The non-condensable gas in the condenser enters the recovery heater and is mixed with the residual carbon flue gas for heating before returning to the thermal cracking reactor for reuse;

[0017] After the pyrolysis is completed, the heating is stopped, and the pyrolysis reactor is allowed to cool naturally to room temperature in a sealed state, and the biochar in the pyrolysis reactor is taken out and weighed;

[0018] Take the liquid receiving tank and let the liquid settle naturally for 12 to 72 hours, separate the wood vinegar liquid on the upper layer and the biomass oil on the lower layer and weigh them respectively;

[0019] Using dichloromethane, carbon dichloride or carbon tetrachloride as an extractant, extracting the wood vinegar according to a volume ratio of wood vinegar to the extractant of 4:1 to 6:1 to obtain phenolic compounds, and weighing them.

[0020] Furthermore, the step of drying the walnut shells includes sending the walnut shells into a dryer, controlling the temperature in the range of 40 to 80° C. to dry the walnut shells until the moisture content of the walnut shells is 5 to 8 wt %.

[0021] Furthermore, the walnut shell crushing step includes placing the dried walnut shell in a crusher and crushing it into walnut shell particles with a particle size of 8 to 20 meshes.

[0022] Preferably, the particle size of the walnut shell particles is 10 mesh.

[0023] Preferably, the initial heating of the thermal cracking reactor is heating to a temperature of 300°C.

[0024] Preferably, the thermal cracking reactor is reheated to a temperature of 550°C.

[0025] Preferably, the natural sedimentation time of the liquid is 48 hours.

[0026] Furthermore, the device for preparing wood vinegar using walnut shells comprises a thermal cracking reactor;

[0027] The feed port of the thermal cracking reactor is connected to the silo of the automatic feeder through a pipeline, the exhaust port of the thermal cracking reactor is connected to the dust collector pipeline, the dust collector exhaust port is connected to the condenser pipeline, and the condenser liquid outlet is connected to the liquid receiving tank pipeline;

[0028] The dust collector smoke outlet is connected to the recovery heater pipeline, and the condenser exhaust port is connected to the recovery heater pipeline;

[0029] The recovery heater is connected to the thermal cracking reactor pipeline;

[0030] A crusher and a dryer are arranged at the entrance of the silo.

[0031] Furthermore, the extraction of phenolic compounds from wood vinegar comprises the following steps:

[0032] Mixing the wood vinegar and the extractant and stirring for 20 to 40 minutes to obtain a mixture;

[0033] separating the mixture to obtain an extract phase containing phenolic compounds;

[0034] The phenolic compounds are obtained by removing the extractant in the extract phase by evaporation or distillation.

[0035] Furthermore, the step of separating the mixture to obtain an extract phase containing phenolic compounds comprises separating the mixture into two phases by centrifugal treatment using a centrifuge, and then obtaining an extract phase containing phenolic compounds by liquid separation, the speed of the centrifuge is 2500-3500 rpm, and the centrifugation time is 15-25 min;

[0036] The step of removing the extractant in the extraction phase to obtain the phenolic compound comprises evaporating the extraction phase in a rotary evaporator, recovering and weighing the evaporated extractant, and concentrating the remaining liquid after evaporation at a temperature of 35-45° C. to obtain the phenolic compound.

[0037] The present invention provides a method for preparing wood vinegar and phenolic compounds by using walnut shells. By accurately controlling the thermal cracking temperature, the heating rate, the residence time of the gas phase in the thermal cracking reactor and the condensation temperature, the yield and purity of the product are significantly improved. By optimizing these key process parameters, the present invention not only achieves an increase of about 15% in the yield of wood vinegar and phenolic compounds, but also ensures the high purity of the product, thereby improving the efficiency and economy of the overall industry.

[0038] In addition, the method for preparing wood vinegar and phenolic compounds using walnut shells provided by the present invention can quickly heat the raw materials in a short time through a high heating rate, thereby improving the pyrolysis efficiency, and controlling the short gas phase residence time to ensure that the cracking products can be quickly condensed subsequently, reduce the occurrence of secondary reactions, and effectively control the reaction process, thereby reducing energy and raw material consumption and the generation of by-products.

[0039] At the same time, the present invention provides a method for preparing wood vinegar and phenolic compounds using walnut shells. In the condensation process, by controlling the condensation temperature between 20 and 25° C., wood vinegar with a higher purity can be obtained. Moreover, when the present invention extracts phenolic compounds from wood vinegar by an extraction method, by controlling the volume ratio of wood vinegar to the extractant and by selecting dichloromethane, carbon dichloride or carbon tetrachloride as the extractant for multiple independent extractions, phenolic compounds with a purity of more than 78% can be obtained, and the extraction efficiency is good.

[0040] In addition, the present invention provides a method for preparing wood vinegar and phenolic compounds using walnut shells. By using walnut shells, a common waste, as raw materials to prepare wood vinegar and phenolic compounds, resource recovery and reuse can be achieved, the environmental burden is reduced, new technical support is provided for green chemistry and environmental protection industries, and the concept of sustainable development is met. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the structure of a device for preparing wood vinegar using walnut shells provided in an embodiment of the present invention;

[0042] Figure 2 A flow chart of a method for preparing wood vinegar and phenolic compounds using walnut shells provided in an embodiment of the present invention.

[0043] Among them, 1. thermal cracking reactor; 2. dust collector; 3. condenser; 4. liquid receiving tank; 5. silo; 6. recovery heater; 7. crusher; 8. dryer. DETAILED DESCRIPTION

[0044] See also Figure 1 In a method for preparing wood vinegar and phenolic compounds using walnut shells provided by an embodiment of the present invention, the device for preparing wood vinegar using walnut shells includes a thermal cracking reactor 1. The feed port of the thermal cracking reactor 1 is connected to the silo 5 of the automatic feeder through a pipeline, the exhaust port of the thermal cracking reactor 1 is connected to the dust collector 2 through a pipeline, the exhaust port of the dust collector 2 is connected to the condenser 3 through a pipeline, and the liquid outlet of the condenser 3 is connected to the liquid receiving tank 4 through a pipeline.

[0045] The smoke outlet of the dust collector 2 is connected to the recovery heater 6 through a pipeline, and the exhaust port of the condenser 3 is also connected to the recovery heater 6 through a pipeline.

[0046] Furthermore, the recovery heater 6 is connected to the thermal cracking reactor 1 through a pipeline.

[0047] A pulverizer 7 and a dryer 8 are arranged above the entrance of the silo 5 of the automatic feeder to facilitate feeding of the silo 5 .

[0048] As a specific implementation of the present invention, the dust collector 2 is a Shaklon dust collector.

[0049] As a specific implementation of the present invention, the condenser 3 is a box-type condenser.

[0050] See also Figure 2 The present invention provides a method for preparing wood vinegar and phenolic compounds using walnut shells, comprising the following steps:

[0051] Step 1) drying and crushing the walnut shells to obtain walnut shell particles.

[0052] When the walnut shells are dried, the walnut shells are sent into a drying machine 8, and the temperature is controlled at 40-80° C. to dry the walnut shells until the moisture content of the walnut shells reaches 5-8wt%.

[0053] The dried walnut shells are then directly discharged into the grinder 7 through a pipeline connected between the dryer 8 and the grinder 7 for crushing. In order to achieve the purpose of sealing the silo 5 with the crushed walnut shell particles, as a specific embodiment of the present invention, the walnut shells are crushed into walnut shell particles with a particle size of 8 to 20 meshes.

[0054] In order to achieve the best sealing effect of the crushed walnut shell particles on the silo 5, as a best embodiment of the present invention, the walnut shells are crushed into walnut shell particles with a particle size of 10 mesh.

[0055] Step 2) a certain amount of walnut shell particles is weighed and placed in a silo 5, and the silo 5 is connected to the thermal cracking reactor 1 by a pipeline. By weighing a certain amount of walnut shell particles, the feed amount of the walnut shell particles can be accurately controlled, thereby ensuring the accurate input of the raw materials during the reaction process, so as to facilitate the subsequent weighing of the quality and reaction efficiency of the obtained product. In addition, by accurately controlling the feed amount of the walnut shell particles, the properties and yields of the obtained products under different reaction conditions can be accurately compared, thereby determining the preparation effect of the present invention.

[0056] Step 3) The thermal cracking reactor 1 is initially heated to 200-350° C., 20-25% of walnut shell particles are added to the thermal cracking reactor 1 through the silo 5, and the air in the thermal cracking reactor 1 is exhausted by the generated cracking gas.

[0057] As a best embodiment of the present invention, the initial heating of the thermal cracking reactor is preferably heated to a temperature of 300°C.

[0058] Since the gas phase produced by thermal cracking of walnut shells contains flammable components, these flammable components are prone to oxidation reaction with oxygen in the air, and if the explosion limit of the flammable components is reached, there is also a risk of explosion during the heating process. Therefore, in order to effectively curb the oxidation reaction between the gas phase components that may be produced by the thermal cracking of walnut shells and oxygen in the air, and thus prevent potential explosion risks, a small amount of walnut shells is first introduced into the reactor 1 for thermal cracking, and the cracking gas produced is used to gradually replace the original air in the reactor, thereby enhancing the safety, selectivity and yield of the thermal cracking reaction, while ensuring the high purity characteristics of the final product.

[0059] Step 4) After the air in the thermal cracking reactor 1 is fully exhausted, the thermal cracking reactor 1 is connected to the dust collector 2, the condenser 3 and the liquid receiving tank 4 in sequence through pipelines.

[0060] Step 5) Add the remaining walnut shell particles in the silo 5 into the thermal cracking reactor 1 and 4 ~10 5 The thermal cracking reactor 1 is heated again to 400-600° C. at a heating rate of 0.1 K / s to perform a thermal cracking reaction on the walnut shell particles in the thermal cracking reactor 1.

[0061] As a best embodiment of the present invention, the reheating of the thermal cracking reactor is preferably heated to a temperature of 550°C.

[0062] By 10 4 ~10 5 The heating rate of 1000 K / s can rapidly increase the temperature in the thermal cracking reactor 1 to 400-600° C., so that the raw material can be quickly heated in a short time, and the thermal decomposition efficiency of the walnut shell particles can be improved. Moreover, by controlling the thermal cracking temperature at 400-600° C., wood vinegar can be thermally cracked from the walnut shell particles as much as possible, thereby improving the yield and quality of wood vinegar.

[0063] Step 6) The thermal cracking reactor 1 adopts a flash thermal cracking mode, which can make the generated cracked gas stay in the thermal cracking reactor 1 for no more than 2 seconds and then enter the dust collector 2 for purification and dust removal. The residence time of the gas phase generated by the thermal cracking of the thermal cracking reactor 1 in the thermal cracking reactor 1 is controlled within a very short time, which can ensure that the thermal cracking gas phase can quickly enter the dust collector 2 and the condenser 3 for subsequent dust removal and condensation, and can reduce the occurrence of secondary reactions of the cracking gas phase, which can not only effectively reduce energy and raw material consumption, but also reduce the generation of by-products and improve the purity of the product wood vinegar.

[0064] Furthermore, as a specific embodiment of the present invention, in order to improve the dust removal efficiency without affecting the wood vinegar gas phase produced by the thermal cracking of walnut shell particles, the dust collector 2 adopts a Shaklon dust collector.

[0065] Step 7) The residual carbon flue gas obtained by purifying and removing dust enters the recovery heater 6, and the obtained pure cracking gas enters the condenser with a temperature of 20-25° C. for condensation.

[0066] As a specific implementation of the present invention, the condenser 3 is a box-type condenser.

[0067] During the condensation process, by controlling the condensation temperature to 20-25° C., it is beneficial to the liquefaction of the wood vinegar components, and wood vinegar with higher purity can be obtained.

[0068] Step 8) The condensate obtained by condensation in the condenser 3 is sent to the liquid receiving tank 4 for storage.

[0069] Step 9) The non-condensable gas in the condenser 3 enters the recovery heater 6 and is mixed with the residual carbon flue gas for heating and then returns to the thermal cracking reactor 1 for reuse, thereby achieving full utilization of heat and effective components and saving resources and energy.

[0070] Step 10) After the pyrolysis is completed, a material seal is formed by sealing the dust collector 2 and storing walnut shell particles with a particle size of 8 to 20 mesh in the hopper of the silo 5, so that the device for preparing wood vinegar using walnut shells is in a closed state, and then the heating is stopped, the pyrolysis reactor 1 is naturally cooled to room temperature, and the biochar in the pyrolysis reactor 1 is taken out and its mass is weighed. The yield of biochar can be calculated by the mass of biochar and the mass of the walnut shell particles initially weighed. The yield of biochar during the pyrolysis of walnut shells can be used to understand the chemical kinetics of the entire pyrolysis process, and the extraction process of biochar involves heating the walnut shells under specific temperature and time conditions to cause pyrolysis, thereby producing biochar, bio-oil and non-condensable gas. As the main solid product of the pyrolysis reaction, the yield and characteristics of biochar can be used to evaluate the pyrolysis efficiency. Therefore, the mass of biochar is accurately weighed, and the influence of pyrolysis conditions on product distribution can be evaluated based on the calculated biochar yield.

[0071] Step 11) Take the liquid receiving tank 4, allow the liquid to settle naturally for 12 to 72 hours, and then separate the wood vinegar in the upper layer and the biomass oil in the lower layer, and weigh the masses of the obtained wood vinegar and biomass oil respectively.

[0072] As an optimal embodiment of the present invention, the natural sedimentation time of the liquid is preferably 48 hours.

[0073] According to the mass of the obtained wood vinegar and the mass of the initially weighed walnut shell particles, it can be calculated that the yield of wood vinegar can reach about 34%. The yield of wood vinegar, a byproduct derived from the production process of traditional charcoal, is relatively low. Usually, only 50 to 100 kilograms of wood vinegar can be obtained for every ton of charcoal produced, and the yield of wood vinegar is about 5% to 10%. In addition, the method for preparing wood vinegar using walnut shells provided by the present invention optimizes the thermal cracking conditions and improves the product separation and purification process, thereby increasing the yield of wood vinegar by about 15% compared with the traditional preparation method.

[0074] Step 12) using dichloromethane, carbon dichloride or carbon tetrachloride as an extractant, extracting the wood vinegar according to a volume ratio of wood vinegar to the extractant of 4:1 to 6:1 to obtain phenolic compounds, and weighing to obtain the mass of the phenolic compounds.

[0075] When the phenolic compounds in wood vinegar are extracted by the extraction method, the volume ratio of wood vinegar to the extractant is controlled and multiple independent extractions are performed by selecting dichloromethane, carbon dichloride or carbon tetrachloride as the extractant, so that the phenolic compounds with a purity of more than 78% can be obtained, and the extraction efficiency is good.

[0076] Wherein, extracting phenolic compounds from wood vinegar comprises the following steps:

[0077] 1) mixing the wood vinegar and the extractant and stirring for 20 to 40 minutes to obtain a mixture;

[0078] 2) separating the mixture to obtain an extract phase containing phenolic compounds;

[0079] 3) removing the extractant in the extraction phase by evaporation or distillation to obtain phenolic compounds.

[0080] The step of separating the mixture to obtain an extract phase containing phenolic compounds comprises separating the mixture into two phases by centrifugal treatment using a centrifuge, and then obtaining an extract phase containing phenolic compounds by liquid separation, wherein the speed of the centrifuge is 2500-3500 rpm and the centrifugation time is 15-25 min;

[0081] The step of removing the extractant from the extraction phase to obtain the phenolic compound comprises evaporating the extraction phase in a rotary evaporator, recovering and weighing the evaporated extractant, and concentrating the remaining liquid after evaporation at a temperature of 35 to 45° C. to obtain the phenolic compound.

[0082] The present invention provides a method for preparing wood vinegar and phenolic compounds using walnut shells, which realizes efficient and environmentally friendly production of wood vinegar by accurately controlling key process parameters such as thermal cracking temperature, heating rate, gas phase residence time and condensation temperature. The method provided by the present invention not only improves the quality and yield of the product, but also reduces production energy consumption and operation complexity, and is also of great significance for promoting the high-value utilization of biomass resources.

[0083] The following is a detailed description of a method for preparing wood vinegar and phenolic compounds using walnut shells provided by the present invention through examples.

[0084] Example 1

[0085] The method for preparing walnut shell thermal cracking wood vinegar comprises the following steps:

[0086] (1) The raw walnut shells are dried in a dryer 8 and then fed into a grinder 7 to be crushed into walnut shell particles with a particle size of 10 meshes. Then, 6.6 kg of the walnut shell particles are weighed.

[0087] (2) The thermal cracking reactor 1 is preheated to 250° C., 1.5 kg of raw material is added as the initial load, and the generated cracking gas replaces the air in the thermal cracking reactor 1.

[0088] (3) The thermal cracking reactor 1 is connected to the Shaklon dust collector 2 and the box-type condenser 3, and condensed water is added to the box-type condenser 3, and the liquid receiving tank 4 is connected at the same time.

[0089] (4) Continue heating, and start feeding when the temperature reaches 400° C. to perform a thermal cracking reaction on the walnut shell particles entering the thermal cracking reactor 1. Control the feed rate to maintain the temperature in the thermal cracking reactor 1 by the heat released by the thermal cracking of the walnut shell particles until all the remaining walnut shell particles are added to the thermal cracking reactor 1.

[0090] (5) The thermal cracking reactor 1 adopts a flash thermal cracking mode. The generated cracking gas stays in the thermal cracking reactor 1 for no more than 2 seconds before entering the dust collector 2. The cracking gas generated by the thermal cracking of the walnut shell particles flashes from the thermal cracking reactor 1 into the dust collector 2 for purification and dust removal. The residual carbon flue gas generated by the dust removal in the dust collector 2 is sent to the recovery heater 6, and the purified gas phase enters the box condenser 3 for condensation.

[0091] (6) The condensate obtained in the box-type condenser 3 is sent to the liquid receiving tank 4 for storage. The quality of the liquid product finally obtained is shown in Table 1.

[0092] (7) The non-condensable gas in the condenser 3 enters the recovery heater 6 and is mixed with the residual carbon flue gas entering from the dust collector 2 for heating, and then returns to the thermal cracking reactor 1 for reuse. The quality of the non-condensable gas generated by the condenser 3 in this embodiment is shown in Table 1.

[0093] (8) After reaching the production capacity, the dust collector 2 is sealed and the material filled in the hopper is passed through the silo 5 to form a material seal, and the heating is stopped. The sealed state is maintained to allow the thermal cracking reactor 1 to naturally cool to room temperature.

[0094] (9) Open the thermal cracking reactor 1, take out the biochar therein and weigh it. The mass of the obtained biochar is shown in Table 1.

[0095] (10) Remove the liquid receiving tank 4 and allow it to settle naturally for 12 hours to separate the upper layer of wood vinegar and the lower layer of biomass oil, and weigh them separately.

[0096] (11) Weigh the obtained wood vinegar, use dichloromethane as an extractant, and add 20 mL of dichloromethane per 100 mL of wood vinegar to perform three independent extractions. Then, separate the liquid to obtain an extract phase containing phenolic compounds, and weigh the extract phase. Then, evaporate the extract phase in a rotary evaporator, recover the evaporated extractant and weigh it, and concentrate the remaining liquid at a temperature of 35 to 45° C. to obtain phenolic compounds.

[0097] Example 2

[0098] The difference from Example 1 is that the raw material particle size is 12 mesh, the temperature for small amount of feeding is 200°C, the temperature for continuous feeding is 450°C, the liquid natural sedimentation time is 48h, and carbon dichloride is the extraction solvent. The other process and process parameters are the same as those in Example 1.

[0099] The masses of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in this example are shown in Table 1.

[0100] Example 3

[0101] The difference from Example 1 is that the raw material particle size is 8 mesh, the temperature for small amount of feeding is 300°C, the temperature for continuous feeding is 600°C, the liquid natural sedimentation time is 36 hours, and carbon tetrachloride is the extraction solvent. The other process and process parameters are the same as those in Example 1.

[0102] The masses of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in this example are shown in Table 1.

[0103] Example 4

[0104] The difference from Example 1 is that the raw material particle size is 16 mesh, the temperature for small amount of feeding is 350°C, the temperature for continuous feeding is 500°C, the natural sedimentation time of liquid is 72h, and carbon dichloride is the extraction solvent. The other process and process parameters are the same as those in Example 1.

[0105] The masses of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in this example are shown in Table 1.

[0106] Example 5

[0107] The difference from Example 1 is that the raw material particle size is 14 mesh, the temperature for small amount of feeding is 250°C, the temperature for continuous feeding is 450°C, the liquid natural sedimentation time is 24h, and carbon tetrachloride is the extraction solvent. The other process and process parameters are the same as those in Example 1.

[0108] The masses of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in this example are shown in Table 1.

[0109] Example 6

[0110] The difference from Example 1 is that the raw material particle size is 10 mesh, the temperature for small amount of feeding is 300°C, the temperature for continuous feeding is 550°C, the liquid natural sedimentation time is 48h, and dichloromethane is the extraction solvent. The other process and process parameters are the same as those in Example 1.

[0111] The masses of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in this example are shown in Table 1.

[0112] Table 1 Mass of gas, liquid and solid products obtained in each embodiment (unit / kg)

[0113] Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Liquid products 2.59 2.66 3.12 3.01 2.89 3.19 Biochar 2.10 1.76 1.53 1.65 1.74 1.58 Non-condensable gas 2.31 2.18 1.95 1.94 1.97 1.83

[0114] The product efficiency of each embodiment can be calculated by the mass of the liquid product, biochar, non-condensable gas and other gas-liquid-solid products obtained in each embodiment. It can be seen from Table 1 that the product efficiency of each embodiment is relatively high, indicating that a method for preparing wood vinegar and phenolic compounds using walnut shells provided in an embodiment of the present invention can improve the quality and yield of the product.

[0115] (12) Among them, after 3.19 kg of liquid product obtained by pyrolysis of 6.6 kg of walnut shell particles weighed in Example 6 of the present invention was naturally settled for 48 hours, the upper layer of wood vinegar and the lower layer of biomass oil were separated by liquid separation method and weighed respectively. The masses of the obtained wood vinegar and biomass oil are shown in Table 2.

[0116] Table 2

[0117] Example 6 Component weight / kg Liquid percentage Percentage of raw materials Biomass oil 0.96 30 14.5 Wood vinegar 2.23 69.9 33.8

[0118] Weigh 383 g of the prepared wood vinegar, and add 383 mL of dichloromethane as an extractant to the wood vinegar.

[0119] Then, an extraction phase containing phenolic compounds is obtained by liquid separation, and the weight of the extraction phase is weighed.

[0120] The extract phase is then evaporated in a rotary evaporator, the evaporated extractant is recovered and weighed, and the remaining liquid after evaporation is concentrated at a temperature of 35 to 45° C. to obtain phenolic compounds.

[0121] In Example 6 of the present invention, the initial amounts of wood vinegar and the extractant dichloromethane at the beginning, the amount of solution obtained after the extractant is recovered, the amount of the extractant used, and the recovery rate of the extractant are shown in Table 3.

[0122] Table 3

[0123] The amount of related Numeric Initial wood vinegar quality 383g Initial amount of dichloromethane 383mL The amount of solution obtained after the extraction agent is recovered 297.9mL Amount of dichloromethane used 383mL Recovery rate of dichloromethane 77.8％

[0124] 383g of phenolic compounds obtained in Example 6 of the present invention were first bleached, and then 84.09g of acid water, creosote, and about 70g of vegetable asphalt were collected. Among them, the creosote accounted for 57.7%. Finally, the 221g of creosote obtained was subjected to chromatographic analysis to obtain the yield of phenolic compounds obtained in Example 6 of the present invention, as shown in Table 4.

[0125] By calculating the value of each component in the phenolic compounds obtained in the examples of the present invention, the value of white creosote is 7,000 to 8,000 yuan, and the value of plant polyphenols can reach 16,700 yuan per ton, indicating that the method for preparing wood vinegar and phenolic compounds using walnut shells provided by the present invention can produce good economic benefits.

[0126] Table 4

[0127]

[0128] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing wood vinegar and phenolic compounds using walnut shells, characterized in that: The steps include: Drying and crushing the walnut shells to obtain walnut shell particles; A certain amount of walnut shell particles is placed in a silo, and the silo is connected to a thermal cracking reactor pipeline; The pyrolysis reactor is initially heated to 200-350° C., 20-25% of walnut shell particles are added to the pyrolysis reactor through a silo, and the air in the pyrolysis reactor is exhausted by the generated pyrolysis gas; The thermal cracking reactor is connected with the dust collector, the condenser and the liquid receiving tank in sequence through pipelines; The remaining walnut shell particles in the silo were added to the thermal cracking reactor and heated at 10 4 ~10 5 The thermal cracking reactor is heated again to 400-600°C at a heating rate of K / s to carry out thermal cracking reaction; The generated cracking gas stays in the thermal cracking reactor for no more than 2 seconds before entering the dust collector for purification and dust removal; The obtained pure cracking gas enters the condenser with a temperature of 20-25°C for condensation, and the residual carbon flue gas obtained by purification and dust removal enters the recovery heater; The condensate obtained by condensation is sent to a liquid receiving tank for storage; The non-condensable gas in the condenser enters the recovery heater and is mixed with the residual carbon flue gas for heating before returning to the thermal cracking reactor for reuse; After the pyrolysis is completed, the heating is stopped, and the pyrolysis reactor is allowed to cool naturally to room temperature in a sealed state, and the biochar in the pyrolysis reactor is taken out and weighed; Take the liquid receiving tank and let the liquid settle naturally for 12 to 72 hours, separate the wood vinegar liquid on the upper layer and the biomass oil on the lower layer and weigh them respectively; Using dichloromethane, carbon dichloride or carbon tetrachloride as an extractant, extracting the wood vinegar according to a volume ratio of wood vinegar to the extractant of 4:1 to 6:1 to obtain phenolic compounds, and weighing them.

2. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 1, characterized in that: The step of drying the walnut shells comprises sending the walnut shells into a drying machine, controlling the temperature at 40-80° C., and drying the walnut shells to a moisture content of 5-8wt%.

3. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 2, characterized in that: The walnut shell crushing step includes placing the dried walnut shell in a crusher and crushing it into walnut shell particles with a particle size of 8 to 20 meshes.

4. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 3, characterized in that: The particle size of the walnut shell particles is 10 meshes.

5. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 1, characterized in that: The thermal cracking reactor is initially heated to a temperature of 300°C.

6. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 1, characterized in that: The thermal cracking reactor is heated again to a temperature of 550°C.

7. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 1, characterized in that: The natural sedimentation time of the liquid is 48h.

8. The method for preparing wood vinegar and phenolic compounds using walnut shells according to any one of claims 1 to 7, characterized in that: The device for preparing wood vinegar using walnut shells comprises a thermal cracking reactor; The feed port of the thermal cracking reactor is connected to the silo of the automatic feeder through a pipeline, the exhaust port of the thermal cracking reactor is connected to the dust collector pipeline, the dust collector exhaust port is connected to the condenser pipeline, and the condenser liquid outlet is connected to the liquid receiving tank pipeline; The dust collector smoke outlet is connected to the recovery heater pipeline, and the condenser exhaust port is connected to the recovery heater pipeline; The recovery heater is connected to the thermal cracking reactor pipeline; A crusher and a dryer are arranged at the entrance of the silo.

9. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 1, characterized in that: The wood vinegar extraction to obtain phenolic compounds comprises the following steps: Mixing the wood vinegar and the extractant and stirring for 20 to 40 minutes to obtain a mixture; separating the mixture to obtain an extract phase containing phenolic compounds; The phenolic compounds are obtained by removing the extractant in the extract phase by evaporation or distillation.

10. The method for preparing wood vinegar and phenolic compounds using walnut shells according to claim 9, characterized in that: The step of separating the mixture to obtain an extract phase containing phenolic compounds comprises separating the mixture into two phases by centrifugal treatment with a centrifuge, and then obtaining an extract phase containing phenolic compounds by liquid separation, wherein the speed of the centrifuge is 2500-3500 rpm and the centrifugation time is 15-25 min; The step of removing the extractant in the extraction phase to obtain the phenolic compound comprises evaporating the extraction phase in a rotary evaporator, recovering and weighing the evaporated extractant, and concentrating the remaining liquid after evaporation at a temperature of 35-45° C. to obtain the phenolic compound.

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