Method for treating traditional Chinese medicine residues by hydrothermal method

Abstract

The invention relates to a method for treating traditional Chinese medicine residues by a hydrothermal method, which comprises the steps of traditional Chinese medicine residue pretreatment, traditional Chinese medicine residue preheating, traditional Chinese medicine residue heating, hydrothermal carbonization treatment, carbon slurry cooling, solid-liquid separation and the like. The method has the advantages that the treated traditional Chinese medicine residues can be directly used in the fields of zero-carbon fuels or organic carbon fertilizers and the like, one part of the obtained by-product hydrothermal carbonization liquid can be recycled in the system, and the other part of the obtained by-product hydrothermal carbonization liquid can be used as organic liquid fertilizers for agricultural irrigation, so that the recovery effect of the traditional Chinese medicine residues is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial solid waste recycling, specifically relates to the technical field of biomass waste residue recycling, and more specifically relates to a method for treating traditional Chinese medicine residues by a hydrothermal method. Background Art

[0002] With people's recognition of the traditional Chinese medicine industry, the use of traditional Chinese medicine has increased year by year. Traditional Chinese medicine companies usually use water extraction to extract the active ingredients in traditional Chinese medicine. The residual traditional Chinese medicine residue after extraction is a wet material with a moisture content of about 70%. It has a strong odor and is easy to rot. Improper handling will cause serious pollution to the environment.

[0003] my country produces tens of millions of tons of wet-based Chinese medicine residue every year. The traditional means of treatment are landfill and incineration, but there are problems with each: 1) Landfill. For Chinese medicine pharmaceutical companies, according to the "Law on the Prevention and Control of Environmental Pollution by Solid Waste", drug residue belongs to general industrial solid waste and should be disposed of in accordance with the "Pollution Control Standards for General Industrial Solid Waste Storage and Disposal Sites". However, due to the small number of industrial solid waste storage and disposal sites, and the fact that domestic waste landfills generally do not accept industrial solid waste, most Chinese medicine pharmaceutical companies choose to hand over Chinese medicine residue to qualified related companies for landfill treatment, which makes it difficult to ensure the treatment effect. 2) Incineration. Chinese medicine residue has a high moisture content and is difficult to dehydrate. The incineration cost is high, wastes resources and may cause secondary pollution.

[0004] The hydrothermal carbonization process of biomass refers to the process of simulating and accelerating the natural coal-forming process in a subcritical water environment at medium pressure (1-5 MPa) and temperature (180-280°C). After a series of complex chemical reactions such as hydrolysis, dehydration, decarboxylation, and polycondensation, the biomass forms hydrothermal carbon similar to charcoal. Compared with conventional biomass pyrolysis technology, water does not undergo phase change during the hydrothermal carbonization of biomass, and the energy consumption is low. Organic matter with any water content can be used as raw materials, and there is no emission during the reaction process. It is a cutting-edge technology in the field of biomass treatment. After the hydrothermal treatment of biomass, the original cell structure is destroyed, the water in the cell is released, the surface properties change from hydrophilic to hydrophobic, and the solid product is easy to dry and crush. It can be used as a green dye organic carbon fertilizer. At the same time, the by-product hydrothermal carbonization liquid rich in small molecular organic matter and inorganic salts can be used for agricultural irrigation or soil remediation. For organic waste with high water content and complex composition such as Chinese medicine residue, hydrothermal carbonization technology is cleaner and more efficient than conventional treatment processes, and has good application prospects.

[0005] At present, biomass hydrothermal carbonization technology is still in the experimental research stage, and is mainly used for harmless treatment of sludge in the industrial field. However, due to the large differences in the physical and chemical properties of Chinese medicine residues and sludge, it is necessary to transform material transportation, reaction condition control, waste heat recovery and other aspects to meet the needs of industrial production. If a subcritical biomass hydrothermal carbonization process can be invented to treat Chinese medicine residues, it will greatly improve the recycling value of Chinese medicine residues and turn harm into benefit. Summary of the invention

[0006] The invention aims at the shortcomings of traditional Chinese medicine residue treatment process, such as high energy consumption, heavy pollution and difficulty in ensuring treatment effect, and provides a method for efficiently and cleanly achieving harmless treatment of Chinese medicine residue by using hydrothermal carbonization.

[0007] This is achieved through the following technical means:

[0008] A method for treating Chinese medicine residues by hydrothermal method comprises the following steps:

[0009] (1) Pretreatment of Chinese herbal medicine residue: The Chinese herbal medicine residue raw material is placed in a crusher for crushing, and the Chinese herbal medicine residue is crushed into small-sized Chinese herbal medicine residue with an average particle size of 0.1 to 2.0 mm. The crushed small-sized Chinese herbal medicine residue is then transported to a stirring component, and carbonizing liquid and stabilizer are added to stir together to form a raw material slurry.

[0010] (2) Preheating of Chinese medicinal residue: The raw material slurry obtained in step (1) is transported to a preheating heat exchanger for preheating. The preheating heat exchanger is a shell and tube structure, wherein the tube side is the raw material slurry obtained in step (1) and the shell side is high-temperature carbon slurry; or the tube side is high-temperature carbon slurry and the shell side is the raw material slurry obtained in step (1).

[0011] (3) Heating the Chinese medicinal residue: placing the raw material slurry after preheating in step (2) into a steam mixer, and heating the raw material slurry to 180-220° C. by medium-pressure steam to obtain a heated Chinese medicinal residue slurry.

[0012] (4) Hydrothermal carbonization treatment: The Chinese medicine residue slurry obtained in step (3) is placed in a hydrothermal reactor to complete a hydrothermal carbonization reaction in the hydrothermal reactor, wherein the residence time of the hydrothermal carbonization reaction is 1.5 to 3 hours, and a high-temperature carbon slurry after hydrothermal carbonization treatment is obtained.

[0013] (5) Cooling of carbon slurry: The high-temperature carbon slurry obtained in step (4) is first discharged into a high-temperature carbon slurry buffer tank, and then the obtained high-temperature carbon slurry is returned to the tube side or shell side of step (2) to be used as the high-temperature carbon slurry in step (2), and then discharged through a preheating heat exchanger to obtain a low-temperature carbon slurry. The pressure of the low-temperature carbon slurry is reduced to normal pressure (the pressure will decrease while cooling. In order to further ensure complete pressure reduction, a pressure relief component is preferably provided on the preheating heat exchanger or on the pipeline between the preheating heat exchanger and the low-temperature carbon slurry buffer tank. The pressure relief component is preferably a pressure relief valve), and then transported to the low-temperature carbon slurry buffer tank.

[0014] (6) Solid-liquid separation: The low-temperature carbon slurry discharged into the low-temperature carbon slurry buffer tank in step (5) is discharged into the solid-liquid separation component, and solid-liquid separation is performed by the solid-liquid separation component to obtain a hydrothermal carbon cake product and a hydrothermal carbonized liquid. The hydrothermal carbonized liquid is returned to step (1) for use as the carbonized liquid.

[0015] Preferably, in step (1), the water content of the raw material slurry is controlled to be 70-80%, and the stabilizer is a high molecular polymer with thickening properties; the amount of the stabilizer added is 0.05-0.5wt.% of the mass of the raw material slurry.

[0016] Preferably, in step (1), the stabilizer is one or more of cellulose ether, dextrin, soluble starch or sodium polyacrylate.

[0017] Preferably, the conveying is performed by pressurized conveying using a slurry conveying pump, and the raw material slurry obtained in step (1) is pressurized to 2-4 MPa.

[0018] Preferably, in step (1), the ratio of the crushed Chinese medicine residue to the carbonized liquid and the stabilizer is (0.9-1.1): (0.2-1.2): (0.0006-0.011).

[0019] Preferably, in step (3), the medium-pressure steam is medium-pressure steam having a temperature of 190-260° C. and a pressure of 2.0-3.9 MPa, and the amount of medium-pressure steam used is 6-16% of the mass of the raw material slurry after preheating in step (2).

[0020] Preferably, in step (4), the hydrothermal reactor is a tubular hydrothermal reactor, and the diameter of the tubular hydrothermal reactor is 120 to 180 mm (to ensure that the slurry moves in the reactor in a plug flow without back mixing).

[0021] Preferably, in step (5), a steam release valve is provided on the top of the high-temperature buffer tank, and the steam release valve is used to indirectly control the temperature and pressure in the hydrothermal reactor by adjusting the pressure of the high-temperature buffer tank.

[0022] Preferably, the pressure of the high-temperature carbon slurry buffer tank is controlled at 1.2-1.9 MPa; the filling coefficient of the slurry in the high-temperature carbon slurry buffer tank is controlled at 0.5-0.8 (ie, the filling amount is 50-80% of the tank volume).

[0023] Preferably, the temperature of the low-temperature carbon slurry is 38-60°C.

[0024] Preferably, in step (2), the raw material slurry in the tube side and the high-temperature carbon slurry in the shell side flow in opposite directions, or the raw material slurry in the shell side and the high-temperature carbon slurry in the tube side flow in opposite directions; the two exchange heat without direct contact.

[0025] Preferably, the hydrothermal charcoal cake obtained in step (6) is subsequently used as zero-carbon fuel or organic charcoal fertilizer.

[0026] Preferably, 20-60% of the hydrothermal carbonized liquid obtained in step (6) is returned to step (1) for use as carbonized liquid, and the rest is used as organic liquid fertilizer for agricultural irrigation.

[0027] As an alternative, the carbonized liquid in step (1) is replaced by water or a mixture of carbonized liquid and water in any proportion; the hydrothermal carbonized liquid obtained in step (6) is returned to step (1) to replace water or a mixture of carbonized liquid and water in any proportion for use.

[0028] A device for hydrothermally treating Chinese medicine residues, the device is used to carry out the above-mentioned method for hydrothermally treating Chinese medicine residues, the device comprises a pretreatment component, a preheating component, a steam mixer, a hydrothermal reactor, a carbon slurry cooling and pressure relief component and a solid-liquid separation component.

[0029] The pre-treatment component includes a crusher and a stirring component.

[0030] The preheating component includes a slurry delivery pump and a preheating heat exchanger.

[0031] The steam mixer is used to heat the slurry by medium-pressure steam.

[0032] The hydrothermal reactor is used to perform a hydrothermal carbonization reaction on the materials entering therein.

[0033] The carbon slurry cooling and pressure relief component comprises a high-temperature carbon slurry buffer tank, a pressure relief component and a low-temperature carbon slurry buffer tank.

[0034] The solid-liquid separation component is used for performing solid-liquid separation.

[0035] Preferably, the crusher comprises a Chinese medicinal residue raw material inlet and a small-particle Chinese medicinal residue outlet; the stirring component comprises a small-particle Chinese medicinal residue inlet, a carbonization liquid inlet, a stabilizer inlet and a raw material slurry outlet, the lower-particle Chinese medicinal residue inlet is connected to the small-particle Chinese medicinal residue outlet of the crusher, and the stabilizer inlet is used to discharge the stabilizer into the stirring component.

[0036] Preferably, the preheating heat exchanger includes a high-pressure raw material slurry inlet, a preheating raw material slurry outlet, a high-temperature carbon slurry inlet and a low-temperature carbon slurry outlet; the inlet of the slurry delivery pump is connected to the raw material slurry outlet of the stirring component, and the outlet of the slurry delivery pump is connected to the high-pressure raw material slurry inlet of the preheating heat exchanger.

[0037] Preferably, the steam mixer comprises a medium-pressure steam inlet, a preheated raw material slurry inlet and a traditional Chinese medicine residue slurry outlet; the medium-pressure steam inlet is used to discharge medium-pressure steam into the steam mixer, and the preheated raw material slurry inlet is connected to the preheated raw material slurry outlet of the preheating heat exchanger.

[0038] Preferably, the hydrothermal reactor comprises a high-temperature Chinese medicinal residue slurry inlet and a high-temperature carbon slurry outlet, and the high-temperature Chinese medicinal residue slurry inlet is connected to the Chinese medicinal residue slurry outlet of the steam mixer.

[0039] Preferably, the high-temperature carbon slurry buffer tank includes a high-temperature and high-pressure carbon slurry inlet and a low-pressure carbon slurry outlet, the high-temperature and high-pressure carbon slurry inlet is connected to the high-temperature carbon slurry outlet of the hydrothermal reactor, and the low-pressure carbon slurry outlet is connected to the high-temperature carbon slurry inlet of the preheating heat exchanger.

[0040] Preferably, the pressure relief component is arranged in the high-temperature carbon slurry buffer tank.

[0041] Preferably, the low-temperature carbon slurry buffer tank comprises a low-temperature carbon slurry inlet and a low-temperature low-pressure carbon slurry outlet, and the low-temperature carbon slurry inlet is connected to the low-temperature carbon slurry outlet of the preheating heat exchanger.

[0042] Preferably, the solid-liquid separation component includes a low-temperature and low-pressure carbon slurry inlet, a hydrothermal carbon cake outlet and a hydrothermal carbonization liquid outlet. The low-temperature and low-pressure carbon slurry inlet is connected to the low-temperature and low-pressure carbon slurry outlet of the low-temperature carbon slurry buffer tank. The hydrothermal carbon cake outlet is used to discharge the hydrothermal carbon cake obtained after solid-liquid separation. The hydrothermal carbonization liquid outlet is connected to the carbonization liquid inlet of the stirring component.

[0043] Preferably, the hydrothermal reactor is a tubular hydrothermal reactor, and the tubular hydrothermal reactor is made of a stainless steel inner layer and a rock wool insulation outer layer, wherein the outer layer wraps the inner layer.

[0044] Preferably, the slurry delivery pump is a plunger pump.

[0045] Preferably, the solid-liquid separation device is a plate and frame filter press.

[0046] Preferably, the pressure relief component is a steam relief valve, and the pressure relief component is arranged at the top of the high-temperature carbon slurry buffer tank.

[0047] Preferably, the stirring component is a stirring tank.

[0048] Preferably, the preheating heat exchanger is a shell and tube structure.

[0049] Preferably, the crusher is a colloid mill or a ball mill.

[0050] The technical effects of the present invention are:

[0051] (1) The present invention uses the principle of hydrothermal carbonization to discharge the water in the Chinese medicine residue in liquid form by setting reasonable pretreatment of the particle size of the Chinese medicine residue, configuring stabilizers and hydrothermal carbonization liquid to stir into slurry, preheating + heating of graded heating, and reasonable hydrothermal carbonization treatment, thereby reducing the energy consumed by the phase change of water in the conventional heat treatment process. The present invention preheats the biomass raw material slurry by recycling the high-temperature carbon slurry after the subsequent reaction, and then further heats the raw material by medium-pressure steam, thereby realizing the cascade utilization of energy and effectively reducing the energy consumption of the system.

[0052] (2) The present invention directly heats the raw material slurry by arranging medium-pressure steam in the steam mixer. Compared with the conventional preheating heat exchanger, the method of directly heating the raw material slurry by medium-pressure steam has higher thermal efficiency and faster control speed. Therefore, the medium-pressure steam heating method and the graded heating method coordinated with the high-temperature slurry preheating further improve the heating effect of the medium-pressure steam heating, thereby greatly improving the thermal efficiency and control speed while ensuring the heating effect.

[0053] (3) The present invention sets the hydrothermal reactor as a tubular reactor, so that the raw material slurry advances in the reactor in a plug flow, avoiding the mixing of unreacted materials and products, and at the same time limiting the residence time of the hydrothermal reaction (preferably setting the tube diameter), by coordinating this time with the specific tubular reactor, and coordinating with the specific waste heat and heating stage heating method, an efficient hydrothermal reaction effect is achieved, and continuous production can be achieved. The tubular reactor can also be folded according to the site conditions while ensuring the above-mentioned efficient production, and the form is flexible, which greatly saves the system's footprint.

[0054] (4) The present invention provides a stabilizer in the raw material, and combines it with a small-particle Chinese medicinal residue and a carbonized liquid. By regulating the composition of the slurry, especially by reasonably setting the stabilizer and combining it with the small-particle Chinese medicinal residue, the water in the carbonized liquid that can act as a lubricant can be evenly distributed in the mixture during transportation in a long-distance pipeline. A stable water film exists around the biomass during high-pressure transportation, so that the Chinese medicinal residue slurry can be stably transported in the long-distance pipeline without clogging, thereby ensuring the stability and reliability of the overall process.

[0055] (5) The present invention indirectly ensures that the reaction of the tubular hydrothermal reactor is under control by setting a specific pressure regulating component (steam release valve) in the high-temperature buffer tank. When the pressure in the tubular reactor is too high, the pressure relief valve of the high-temperature carbon slurry tank buffer tank is opened to release part of the steam, and the pressure in the tank is reduced. Even if the valve opening between the tubular reactor and the high-temperature carbon slurry buffer tank remains unchanged, the carbon slurry inside the tubular reactor will enter the high-temperature carbon slurry buffer tank faster due to the increase in the pressure difference on both sides, thereby reducing the pressure in the tubular reactor. This arrangement is because steam is discharged from the top of the high-temperature carbon slurry buffer tank, and the wear on the valve can be ignored, while the delivery valve passes through carbon slurry, and fine carbon powder can easily enter the valve body when the valve moves, causing valve damage. Therefore, the valve here needs to avoid frequent movement as much as possible to ensure the durability of the equipment. Therefore, the arrangement of the present invention realizes the control of the temperature and pressure in the tubular hydrothermal reactor through the high-temperature buffer tank, while avoiding the equipment wear caused by frequent adjustment of the discharge valve in the existing conventional arrangement, thereby reducing the difficulty of maintenance while ensuring production effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The present invention is a process flow chart of a method for treating Chinese medicine residues by a hydrothermal method according to an embodiment of the present invention.

[0057] In the figure: 1-mill, 2-mixing tank, 3-plunger pump, 4-preheating heat exchanger, 5-steam mixer, 6-hydrothermal reactor, 7-high temperature carbon slurry buffer tank, 8-low temperature carbon slurry buffer tank, 9-plate and frame filter press, A-traditional Chinese medicine residue raw material, B-stabilizer, C-raw material slurry, D-medium pressure steam, E-high temperature carbon slurry, F-low temperature carbon slurry, G-hydrothermal carbon cake product, H-hydrothermal carbonization liquid. DETAILED DESCRIPTION

[0058] The process technology scheme of the present invention is further illustrated below by combining embodiments and drawings. The orientations involved in this specification are based on the orientations of the present invention during normal operation, and do not limit the orientations during storage and transportation. They only represent relative positional relationships, not absolute positional relationships. Specific implementation methods Unless otherwise described, each feature is only an example of a series of equivalent or similar features. Just to help understand the present invention, those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0059] Example 1

[0060] This embodiment is used to illustrate an example of the device for treating Chinese medicine residues by hydrothermal method of the present invention. Figure 1 As shown, the device of this embodiment includes a pretreatment component, a preheating component, a steam mixer, a hydrothermal reactor, a carbon slurry cooling and pressure relief component and a solid-liquid separation component. The pretreatment component includes a crusher and a stirring component. The preheating component includes a slurry delivery pump and a preheating heat exchanger. The steam mixer is used to heat the slurry by medium-pressure steam. The hydrothermal reactor is used to perform a hydrothermal carbonization reaction on the material entering therein. The carbon slurry cooling and pressure relief component includes a high-temperature carbon slurry buffer tank, a pressure relief component and a low-temperature carbon slurry buffer tank. The solid-liquid separation component is used to perform solid-liquid separation.

[0061] like Figure 1 As shown, the crusher of this embodiment is a ball mill, including a Chinese medicine slag raw material inlet and a small-particle Chinese medicine slag outlet; the stirring tank includes a small-particle Chinese medicine slag inlet, a carbonization liquid inlet, a stabilizer inlet and a raw material slurry outlet, the lower particle size Chinese medicine slag inlet is connected to the small particle size Chinese medicine slag outlet of the crusher, and the stabilizer inlet is used to discharge the stabilizer into the stirring component.

[0062] like Figure 1 As shown, the preheating heat exchanger is a shell and tube structure, including a high-pressure raw material slurry inlet, a preheating raw material slurry outlet, a high-temperature carbon slurry inlet and a low-temperature carbon slurry outlet; the slurry delivery pump is a plunger pump, the inlet of the slurry delivery pump is connected to the raw material slurry outlet of the stirring component, and the outlet of the slurry delivery pump is connected to the high-pressure raw material slurry inlet of the preheating heat exchanger.

[0063] like Figure 1 As shown, the steam mixer includes a medium-pressure steam inlet, a preheating raw material slurry inlet and a traditional Chinese medicine residue slurry outlet; the medium-pressure steam inlet is used to discharge medium-pressure steam into the steam mixer, and the preheating raw material slurry inlet is connected to the preheating raw material slurry outlet of the preheating heat exchanger.

[0064] like Figure 1As shown, the hydrothermal reactor includes a high-temperature Chinese medicine residue slurry inlet and a high-temperature carbon slurry outlet, and the high-temperature Chinese medicine residue slurry inlet is connected to the Chinese medicine residue slurry outlet of the steam mixer. In this embodiment, the hydrothermal reactor is a tubular hydrothermal reactor, and the tubular hydrothermal reactor is made of stainless steel for the inner layer and rock wool insulation for the outer layer, and the outer layer wraps the inner layer.

[0065] like Figure 1 As shown, the high-temperature carbon slurry buffer tank includes a high-temperature and high-pressure carbon slurry inlet and a low-pressure carbon slurry outlet. The high-temperature and high-pressure carbon slurry inlet is connected to the high-temperature carbon slurry outlet of the hydrothermal reactor, and the low-pressure carbon slurry outlet is connected to the high-temperature carbon slurry inlet of the preheating heat exchanger.

[0066] In this embodiment, the pressure relief component is arranged in the high-temperature carbon slurry buffer tank. The pressure relief component is a steam release valve, and the pressure relief component is arranged at the top of the high-temperature carbon slurry buffer tank.

[0067] like Figure 1 As shown, the low-temperature carbon slurry buffer tank includes a low-temperature carbon slurry inlet and a low-temperature low-pressure carbon slurry outlet, and the low-temperature carbon slurry inlet is connected to the low-temperature carbon slurry outlet of the preheating heat exchanger.

[0068] like Figure 1 As shown, the solid-liquid separation component is a plate and frame filter press, including a low-temperature and low-pressure carbon slurry inlet, a hydrothermal carbon cake outlet and a hydrothermal carbonization liquid outlet, the low-temperature and low-pressure carbon slurry inlet is connected to the low-temperature and low-pressure carbon slurry outlet of the low-temperature carbon slurry buffer tank, the hydrothermal carbon cake outlet is used to discharge the hydrothermal carbon cake obtained after solid-liquid separation, and the hydrothermal carbonization liquid outlet is connected to the carbonization liquid inlet of the stirring component.

[0069] Example 2

[0070] This embodiment is a method for treating Chinese medicine residues by hydrothermal method using the device described in Example 1, and this embodiment is carried out in a pharmaceutical factory in Xinjiang. The physical and chemical properties of the Chinese medicine residues as raw materials are shown in Table 1. Table 1 shows the physical and chemical properties of the Chinese medicine residues.

[0071] Table 1

[0072]

[0073] The process of treating the Chinese medicine residues by hydrothermal method using the Chinese medicine residue raw materials in Table 1 comprises the following steps:

[0074] (1) Pretreatment of Chinese medicine residue: Use a ball mill to crush the Chinese medicine residue to a size basically within the range of 0.5 to 1.5 mm. The average particle size of this embodiment is 1.1 mm. Transfer it to a stirring tank, add 0.6 times the weight of carbonization liquid and 0.002 times the weight of sodium carboxymethyl cellulose to prepare a raw material slurry with a moisture content of 75%.

[0075] (2) Preheating of Chinese medicine residue: The raw material slurry obtained in step (1) is pressurized to 3 MPa by a plunger pump and enters the preheating heat exchanger. The preheating pipeline is a shell-and-tube structure, the tube side is the biomass raw material slurry, and the shell side is the high-temperature hydrothermal carbon slurry after the reaction. The biomass raw material slurry stays in the preheating heat exchanger for 45 minutes and is preheated to about 150°C.

[0076] (3) Heating the Chinese herbal medicine residue: The raw material slurry after preheating in step (2) is placed in a steam mixer and heated to 200° C. using medium-pressure steam at 230° C. and 2.8 MPa. The amount of medium-pressure steam used is approximately 10% of the mass of the Chinese herbal medicine residue slurry.

[0077] (4) Hydrothermal carbonization treatment: The Chinese medicine residue slurry obtained in step (3) and reaching 200° C. is placed in a tubular hydrothermal reactor with an inner diameter of 150 mm and made of 316L stainless steel. The slurry stays in the hydrothermal reactor for 2 hours to complete carbonization.

[0078] (5) Carbon slurry cooling: After the hydrothermal carbonization, the high-temperature carbon slurry first enters the high-temperature carbon slurry buffer tank. The filling coefficient of the slurry in the high-temperature carbon slurry buffer tank is controlled at 0.5-0.8, and the pressure of the high-temperature carbon slurry buffer tank is controlled at 1.4-1.7MPa. Then the high-temperature carbon slurry enters the shell side of the preheating pipeline to preheat the Chinese medicine residue slurry. After cooling itself to about 50°C, it is transported into the low-temperature carbon slurry buffer tank through the pressure relief device.

[0079] (6) Solid-liquid separation: The low-temperature carbon slurry is delivered to a plate and frame filter press by a delivery pump for solid-liquid separation to obtain a hydrothermal carbon cake and a hydrothermal carbonized liquid with a water content of about 30%. The physical and chemical properties of the hydrothermal carbon cake and the hydrothermal carbonized liquid are shown in Tables 2 and 3. The hydrothermal carbon cake can be used as a zero-carbon fuel or an organic carbon fertilizer. 40% of the carbonized liquid is returned to the stirring tank for slurrying of traditional Chinese medicine residues, and the rest can be used as an organic liquid fertilizer for agriculture or park irrigation. Table 2 shows the physical and chemical properties of the hydrothermal carbon cake product obtained in Example 2, and Table 3 shows the physical and chemical properties of the hydrothermal carbonized liquid obtained in step (6) of Example 2.

[0080] Table 2

[0081]

[0082] Table 3

[0083]

[0084] It can be concluded from Table 2 and Table 3 that the water content of the hydrothermal carbon cake product is as low as about 30%, and the hydrothermal carbon has low hydrophilicity and is easy to dry. The hydrothermal carbon has high fixed carbon content, low ash content and high calorific value, which indicates that the hydrothermal carbon product obtained in this embodiment fully meets the index of being able to be used as zero-carbon fuel or organic carbon fertilizer, and the hydrothermal carbonized liquid is rich in small molecular organic matter and potassium, and does not contain a limited amount of harmful elements, so it can be used as organic liquid fertilizer for agricultural irrigation. The reuse of the hydrothermal carbonized liquid will enrich the solute, thereby increasing the effective component content of the carbonized liquid product finally discharged, which is more suitable for transportation or concentration.

[0085] In other embodiments, the average particle size of the small-particle Chinese medicinal residue in step (1) is, for example, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 mm, etc. The maximum particle size does not exceed, for example, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2 mm, etc.

[0086] In other embodiments, the heating temperature in step (3) is, for example, 185, 188, 190, 195, 201, 208, 210, 215, 218°C, etc.

[0087] In other embodiments, the residence time of the hydrothermal carbonization reaction in step (4) is, for example, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 h, etc.

[0088] In other embodiments, the water content of the raw material slurry in step (1) is controlled to be, for example, 73, 75, 78, 79%, etc. The amount of stabilizer added is, for example, 0.06, 0.08, 0.15, 0.28, 0.36, 0.48 wt.% of the mass of the raw material slurry.

[0089] In other embodiments, the ratio of the crushed Chinese medicine residue to the carbonized liquid and the stabilizer in step (1) is, for example, 1: (0.38, 0.41, 0.52, 0.63, 0.75, 0.81, 0.6, etc.): (0.0006, 0.0009, 0.0011, 0.0018, 0.0026, 0.0033, 0.0036, 0.0038, etc.).

[0090] In other embodiments, in step (3), the medium-pressure steam is medium-pressure steam having a temperature of, for example, 192, 201, 215, 223, 238, 246, 251, 259° C., and a pressure of, for example, 2.1, 2.3, 2.9, 3.1, 3.5, 3.8 MPa, and the amount of medium-pressure steam is 6.8, 7.3, 8.1, 9.5, 10.9, 11.3, 12.8, 13.2, 14.1, 15.6% of the mass of the raw material slurry after preheating in step (2).

[0091] In other embodiments, in step (4), the diameter of the tubular hydrothermal reactor is, for example, 125, 138, 143, 152, 168, 171, 179 mm, etc.

[0092] In other embodiments, 35, 41, 46, 49, 51, 52%, etc. of the hydrothermal carbonized liquid obtained in step (6) is returned to step (1) for use as the carbonized liquid.

[0093] Comparative Example 1

[0094] This comparative example is a comparative test for shortening the hydrothermal carbonization residence time. The difference from Example 2 is that in step (4), the residence time of the Chinese medicine slurry in the hydrothermal reactor is 1 hour, and the other settings are exactly the same as those in Example 2. The physicochemical analysis of the hydrothermal carbon obtained under this condition is shown in Table 4. Table 4 shows the physicochemical properties of the hydrothermal carbon cake product obtained in Comparative Example 1.

[0095] Table 4

[0096]

[0097] From Table 4 and comparison with Table 2, it can be seen that due to the short hydrothermal carbonization time of this comparative example, when other parameters are the same as those of Example 2, the carbonization degree of the medicinal residue in this comparative example is low (the fixed carbon in this comparative example is only about 40% of the product in Example 2, but the moisture content is about 60 percentage points higher than that in Example 2, and the calorific value is also reduced), the moisture content of the obtained charcoal cake is high, and the waste reduction effect is limited. At this time, the organic matter content in the charcoal cake is higher than the standard of 5% of general industrial solid waste, and special treatment is still required, resulting in inadequate treatment. That is, the specific parameters set by the present invention are closely coordinated with the steps and other parameters of the present invention, and even if only one of them is changed, the final product will be very different.

[0098] Comparative Example 2

[0099] This comparative example is a comparison test without adding a stabilizer. The difference from Example 2 is that no stabilizer is added during the preparation of the slurry in step (1), and the other settings are exactly the same as in Example 2. During the process of this comparative example, it was found that the system was frequently shut down due to pipeline blockage. After analysis, it was concluded that if no stabilizer is used during pulping, once the slurry is squeezed, the water that should have played a lubricating role between the Chinese medicine residue particles will be discharged in large quantities, causing the Chinese medicine residue to cross-link to form a hard precipitate, causing pipeline blockage. The stabilizer can strengthen the interaction between the Chinese medicine residue particles and water, and there is a stable water film around the biomass during the high-pressure transportation process, ensuring the stable transportation of the slurry. Therefore, the specific material raw material ratios set by the present invention do not play their own independent roles, but have a coordinated effect with each other.

[0100] Comparative Example 3

[0101] This comparative example is a comparative test of using an indirect preheating heat exchanger to raise the temperature of the preheated carbon slurry. The difference from Example 2 is that step (3) does not use a steam mixer, but uses a shell and tube preheating heat exchanger to pass medium-pressure steam through the shell side, that is, the preheated Chinese medicine residue slurry passes through the shell side of the shell and tube preheating heat exchanger, and 230°C medium-pressure steam passes through the shell and tube preheating heat exchanger tube side, so that the slurry temperature is raised from 150°C to 200°C. The other settings are the same as Example 2. Since the heat exchange efficiency of the shell and tube preheating heat exchanger is relatively low, it is found through comparative testing that the consumption of medium-pressure steam in this comparative example is about 1.5 to 1.6 times that of Example 2. Although the cold steam in the intermittent preheating heat exchanger can be recycled to save part of the softened water, the comprehensive cost is still higher than that of the steam mixer. That is, the specific device components of the present invention are also closely coordinated with the various parameters of the specific method of the present invention.

[0102] Comparative Example 4

[0103] This comparative example is a comparative test without using a high-temperature carbon slurry stabilization tank. The difference from Example 2 is that in step (5), the high-temperature carbon slurry obtained by hydrothermal treatment does not pass through a high-temperature carbon slurry stabilization tank, but directly enters the shell side of the preheating heat exchanger through a discharge valve. The other settings are the same as those in Example 2. During the implementation of this comparative example, the discharge valve is often stuck, the hydrothermal reactor cannot be adjusted, and it is broken and shut down. When the valve was disassembled, it was found that tiny hydrothermal carbon particles had entered the movable mechanism of the valve, causing the valve to fail to work normally. The temperature and pressure control of the hydrothermal reactor in this comparative example is achieved by adjusting the opening of the discharge valve. In order to ensure the stability of the reaction conditions in the hydrothermal reactor, the discharge valve frequently adjusts its opening under the control of the control system, which increases the probability of hydrothermal carbon particles entering the valve body. In Example 2, the temperature and pressure in the hydrothermal reactor are indirectly controlled by adjusting the pressure of the high-temperature carbon slurry buffer tank. The opening of the discharge valve can basically remain stable, which greatly reduces the probability of failure. When the pressure of the high-temperature carbon slurry buffer tank is adjusted, the medium flowing through the pressure relief valve is steam, which is not easy to cause damage to the valve. Therefore, Example 2 of the present invention makes specific arrangements and selections for each component to make the system have higher stability, thereby ensuring the overall stability of the method process.

[0104] The technical principles and examples of the present invention are described above in conjunction with specific embodiments. The above embodiments and comparative examples of the present invention are all examples and do not have a limiting effect on the protection scope of the technical solution. The technical effects that are not compared can be clearly described through the textual description of the technical effects, and do not mean that the invention is low in height. These descriptions are only for explaining the principles and examples of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementations of the present invention without creative labor, and these methods will fall within the protection scope of the present invention.

Claims

1. A method for treating Chinese medicine residues by hydrothermal method, characterized in that: The steps include: (1) Pretreatment of Chinese medicine residue: placing the Chinese medicine residue raw material into a crusher for crushing, crushing the Chinese medicine residue into small-sized Chinese medicine residue with an average particle size of 0.1 to 2.0 mm, and then conveying the crushed small-sized Chinese medicine residue into a stirring component, adding carbonizing liquid and stabilizer, and stirring together to form a raw material slurry; (2) Preheating the Chinese medicinal residue: The raw material slurry obtained in step (1) is transported to a preheating heat exchanger for preheating. The preheating heat exchanger is a shell-and-tube structure, wherein the tube side is the raw material slurry obtained in step (1) and the shell side is high-temperature carbon slurry; or the tube side is high-temperature carbon slurry and the shell side is the raw material slurry obtained in step (1); (3) Heating the Chinese medicine residue: placing the raw material slurry after preheating in step (2) into a steam mixer, and heating the raw material slurry to 180-220° C. by medium-pressure steam to obtain a heated Chinese medicine residue slurry; (4) hydrothermal carbonization treatment: placing the Chinese medicine residue slurry obtained in step (3) into a hydrothermal reactor to complete a hydrothermal carbonization reaction in the hydrothermal reactor, wherein the residence time of the hydrothermal carbonization reaction is 1.5 to 3 hours, and obtaining a high-temperature carbon slurry after hydrothermal carbonization treatment; (5) cooling the carbon slurry: the high-temperature carbon slurry obtained in step (4) is first discharged into a high-temperature carbon slurry buffer tank, and then the obtained high-temperature carbon slurry is returned to the tube side or shell side of step (2) to be used as the high-temperature carbon slurry in step (2), and then discharged through a preheating heat exchanger to obtain a low-temperature carbon slurry, the pressure of the low-temperature carbon slurry is reduced to normal pressure, and then transported to a low-temperature carbon slurry buffer tank; (6) Solid-liquid separation: The low-temperature carbon slurry discharged into the low-temperature carbon slurry buffer tank in step (5) is discharged into the solid-liquid separation component, and solid-liquid separation is performed by the solid-liquid separation component to obtain a hydrothermal carbon cake product and a hydrothermal carbonized liquid. The hydrothermal carbonized liquid is returned to step (1) for use as the carbonized liquid.

2. The method for treating Chinese medicinal residues by hydrothermal method according to claim 1, characterized in that: In step (1), the water content of the raw material slurry is controlled to be 70-80%, and the stabilizer is a high molecular polymer with thickening properties; the amount of the stabilizer added is 0.05-0.5wt.% of the mass of the raw material slurry; In step (1), the stabilizer is one or more of cellulose ether, dextrin, soluble starch or sodium polyacrylate.

3. The method for treating Chinese medicinal residues by hydrothermal method according to claim 1, characterized in that: In step (2), the conveying is performed by pressurized conveying using a slurry conveying pump, and the raw material slurry obtained in step (1) is pressurized to 2-4 MPa.

4. The method for treating Chinese medicinal residues by hydrothermal method according to claim 3, characterized in that: The ratio of the crushed Chinese medicine residue to the carbonized liquid and the stabilizer in step (1) is (0.9-1.1): (0.2-1.2): (0.0006-0.011); In step (3), the medium-pressure steam has a temperature of 190 to 260° C. and a pressure of 2.0 to 3.9 MPa. The amount of the medium-pressure steam is 6 to 16% of the mass of the raw material slurry after preheating in step (2).

5. The method for treating Chinese medicinal residues by hydrothermal method according to claim 1 or 3, characterized in that: In step (4), the hydrothermal reactor is a tubular hydrothermal reactor, and the diameter of the tubular hydrothermal reactor is 120 to 180 mm; In step (5), a steam release valve is provided on the top of the high-temperature buffer tank, and the steam release valve is used to indirectly control the temperature and pressure in the hydrothermal reactor by adjusting the pressure of the high-temperature buffer tank; In step (2), the raw material slurry in the tube side and the high-temperature carbon slurry in the shell side flow in opposite directions, or the raw material slurry in the shell side and the high-temperature carbon slurry in the tube side flow in opposite directions; the two exchange heat without direct contact.

6. The method for treating Chinese medicinal residues by hydrothermal method according to claim 1 or 3, characterized in that: The hydrothermal carbon cake obtained in step (6) is subsequently used as zero-carbon fuel or organic carbon fertilizer; 20-60% of the hydrothermal carbonized liquid obtained in step (6) is returned to step (1) for use as carbonized liquid, and the rest is used as organic liquid fertilizer for agricultural irrigation.

7. The method for treating Chinese medicinal residues by hydrothermal method according to claim 1, characterized in that: The carbonized liquid in step (1) is replaced with water or a mixture of carbonized liquid and water in any proportion; the hydrothermal carbonized liquid obtained in step (6) is returned to step (1) to replace water or a mixture of carbonized liquid and water in any proportion for use.

8. A device for treating Chinese medicine residues by hydrothermal method, characterized in that: The device is used to carry out the method for treating Chinese medicine residues by hydrothermal method according to any one of claims 1 to 7, and the device comprises a pretreatment component, a preheating component, a steam mixer, a hydrothermal reactor, a carbon slurry cooling and pressure relief component, and a solid-liquid separation component; The pre-treatment component includes a crusher and a stirring component; The preheating component includes a slurry delivery pump and a preheating heat exchanger; The steam mixer is used to heat the slurry by medium-pressure steam; The hydrothermal reactor is used to perform a hydrothermal carbonization reaction on the materials entering therein; The carbon slurry cooling and pressure relief components include a high-temperature carbon slurry buffer tank, a pressure relief component and a low-temperature carbon slurry buffer tank; The solid-liquid separation component is used for performing solid-liquid separation.

9. The device for treating Chinese medicinal residues by hydrothermal method according to claim 8, characterized in that: The crusher includes a Chinese medicine residue raw material inlet and a small-size Chinese medicine residue outlet; the stirring component includes a small-size Chinese medicine residue inlet, a carbonization liquid inlet, a stabilizer inlet and a raw material slurry outlet, the lower-size Chinese medicine residue inlet is connected to the small-size Chinese medicine residue outlet of the crusher, and the stabilizer inlet is used to discharge the stabilizer into the stirring component; The preheating heat exchanger includes a high-pressure raw material slurry inlet, a preheating raw material slurry outlet, a high-temperature carbon slurry inlet and a low-temperature carbon slurry outlet; the inlet of the slurry delivery pump is connected to the raw material slurry outlet of the stirring component, and the outlet of the slurry delivery pump is connected to the high-pressure raw material slurry inlet of the preheating heat exchanger; The steam mixer comprises a medium-pressure steam inlet, a preheated raw material slurry inlet and a Chinese medicine residue slurry outlet; the medium-pressure steam inlet is used to discharge medium-pressure steam into the steam mixer, and the preheated raw material slurry inlet is connected to the preheated raw material slurry outlet of the preheating heat exchanger; The hydrothermal reactor comprises a high-temperature Chinese medicine residue slurry inlet and a high-temperature carbon slurry outlet, and the high-temperature Chinese medicine residue slurry inlet is connected to the Chinese medicine residue slurry outlet of the steam mixer; The high-temperature carbon slurry buffer tank comprises a high-temperature and high-pressure carbon slurry inlet and a low-pressure carbon slurry outlet, wherein the high-temperature and high-pressure carbon slurry inlet is connected to the high-temperature carbon slurry outlet of the hydrothermal reactor, and the low-pressure carbon slurry outlet is connected to the high-temperature carbon slurry inlet of the preheating heat exchanger; The pressure relief component is arranged in the high-temperature carbon slurry buffer tank; The low-temperature carbon slurry buffer tank comprises a low-temperature carbon slurry inlet and a low-temperature low-pressure carbon slurry outlet, and the low-temperature carbon slurry inlet is connected to the low-temperature carbon slurry outlet of the preheating heat exchanger; The solid-liquid separation component includes a low-temperature and low-pressure carbon slurry inlet, a hydrothermal carbon cake outlet and a hydrothermal carbonization liquid outlet. The low-temperature and low-pressure carbon slurry inlet is connected to the low-temperature and low-pressure carbon slurry outlet of the low-temperature carbon slurry buffer tank. The hydrothermal carbon cake outlet is used to discharge the hydrothermal carbon cake obtained after solid-liquid separation. The hydrothermal carbonization liquid outlet is connected to the carbonization liquid inlet of the stirring component.

10. The device for treating Chinese medicinal residues by hydrothermal method according to claim 8, characterized in that: The hydrothermal reactor is a tubular hydrothermal reactor, and the tubular hydrothermal reactor is made of stainless steel for the inner layer and rock wool insulation for the outer layer, the outer layer wrapping the inner layer; The slurry delivery pump is a plunger pump; The solid-liquid separation device is a plate-frame filter press; The pressure relief component is a steam relief valve, and the pressure relief component is arranged at the top of the high-temperature carbon slurry buffer tank; The stirring component is a stirring tank; The preheating heat exchanger is a shell and tube structure; The crusher is a colloid mill or a ball mill.

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