System and method for continuously preparing organic-inorganic compound fertilizer from biomass

Abstract

The invention belongs to the field of biomass resource utilization, and particularly discloses a system and a method for continuously preparing an organic-inorganic compound fertilizer from biomass, and the method comprises the following steps: mixing a biomass raw material with phosphoric acid, and carrying out first-stage hydrothermal reaction to obtain a first hydrothermal product; then mixing with potassium hydroxide and carrying out second-stage hydrothermal reaction to obtain a second hydrothermal product; adjusting the pH value of the second hydrothermal product with phosphoric acid and enabling potassium in the liquid phase to react with phosphoric acid to generate a potassium phosphate compound, then performing low-temperature dehydration at 55-80 DEG C to obtain an oil-solid mixture, and finally performing oil-solid separation on the oil-solid mixture to prepare the organic-inorganic compound fertilizer. According to the preparation method, the loss of humic acid, phosphorus element and potassium element can be avoided, phosphoric acid reacts with potassium in a liquid phase to generate a potassium phosphate compound, the potassium phosphate compound is retained in a solid phase, finally, the humic acid and the potassium phosphate compound are loaded in pores of the hydrothermal carbon to play a slow release role, and the utilization rate of the fertilizer is effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of biomass resource utilization, and more specifically, relates to a system and method for continuously producing organic-inorganic compound fertilizer from biomass. Background Art

[0002] Soil is the core and foundation of agricultural production, providing the nutrients and nutrients necessary for crop growth. Irrational land use can lead to a variety of problems, including a decrease in soil organic matter content, soil acidification, and soil compaction, ultimately impacting crop yields. Organic-inorganic compound fertilizers combine the advantages of both organic and inorganic fertilizers, rapidly providing the inorganic nutrients necessary for crop growth while improving soil structure through organic matter. They also attract significant attention for their water retention, improved fertilizer utilization, promoted crop growth, and enhanced crop quality and yield.

[0003] Compared with traditional composting technology, hydrothermal humification technology can effectively shorten the production cycle and increase the yield of humic acid, and is more in line with the goal of sustainable development. Existing studies have first prepared the organic part through hydrothermal treatment, and then compounded inorganic fertilizers to prepare organic-inorganic compound fertilizers. For example, CN104529588A discloses a method for producing straw-based organic-inorganic compound fertilizers, which accelerates the straw composting process by hydrothermal pretreatment of crop straw, and turns the straw into organic fertilizer in a short time. The acidic substances produced by the pretreatment are then neutralized with alkaline ash from the biomass power plant to a suitable pH, and other inorganic fertilizers are compounded to obtain organic-inorganic compound fertilizers. However, the pH control is difficult due to the reliance on ash with unstable components. Existing studies have proposed a two-step hydrothermal humification to prepare humic acid, namely acidic hydrothermal treatment and alkaline humification, which greatly improves the effect and yield of biomass hydrothermal humification. CN113563603A discloses a method for preparing humic acid using a two-step hydrothermal process with hydrochloric acid and sodium hydroxide. After the hydrothermal process, the humic acid dissolved in the aqueous phase is separated from the solid product. However, this process can be prone to problems such as incomplete separation and some humic acid remaining in the solid phase, which in turn affects the yield of humic acid. Furthermore, if this method is used to prepare the product for use as fertilizer, it requires additional steps such as dechlorination and sodium removal, as well as the addition of additional inorganic components, which significantly increases production costs. Summary of the Invention

[0004] In response to the defects of the existing technology, the present application provides a system and method for continuously producing organic-inorganic compound fertilizer from biomass, aiming to solve the problems of severe humic acid loss and low production efficiency in the existing compound fertilizer preparation methods.

[0005] According to one aspect of the present application, a method for continuously producing organic-inorganic compound fertilizer from biomass is provided, the method specifically comprising: S1: mixing a biomass raw material with phosphoric acid and performing a first hydrothermal reaction to obtain a first hydrothermal product; S2 mixing the first hydrothermal product with potassium hydroxide and performing a second hydrothermal reaction to obtain a second hydrothermal product; S3 adjusting the pH of the second hydrothermal product with phosphoric acid and causing potassium in the liquid phase to react with the phosphoric acid to generate a potassium phosphate compound, and then performing low-temperature dehydration at 55-80°C to obtain an oil-solid mixture, so that humic acid, phosphorus elements and potassium elements remain in the solid phase; S4 performing oil-solid separation on the oil-solid mixture to produce an organic-inorganic compound fertilizer, which includes hydrothermal carbon and humic acid and a potassium phosphate compound loaded in the pores of the hydrothermal carbon, thereby achieving a slow-release effect.

[0006] Compared with the prior art, the above technical scheme conceived by the present application can avoid introducing elements such as chlorine and sodium that are not environmentally friendly, and the introduced phosphorus and potassium elements can be directly converted into nutrients, effectively improving production efficiency and reducing production costs. In order to avoid the loss of humic acid, phosphorus elements and potassium elements, the present application proposes a process path of adjusting the pH and then performing low-temperature dehydration, which can on the one hand utilize the reaction of phosphoric acid with potassium in the liquid phase to generate a potassium phosphate compound and retain it in the solid phase, and on the other hand avoid the pyrolysis of humic acid, effectively improving the yield of humic acid. The process can load humic acid and a potassium phosphate compound in the pores of hydrothermal carbon to play a slow-release role, effectively improving the utilization rate of the fertilizer.

[0007] As a further preferred, the temperature of the first hydrothermal reaction and the second hydrothermal reaction is 130-220°C.

[0008] As a further preferred, in step S3, the pH of the second hydrothermal product is adjusted to 4-5.

[0009] As a further preferred, in step S4, the oil in the oil-solid mixture is dissolved with a washing solution and solid-liquid separation is performed to obtain a solid product, and then the washing solution on the surface of the solid product is removed to produce an organic-inorganic compound fertilizer.

[0010] According to another aspect of the present application, a system for continuously producing an organic-inorganic compound fertilizer from biomass is provided, which includes a hydrothermal module, a dehydration module, a washing module and a discharge module, wherein: The hydrothermal module is used to mix biomass raw materials with phosphoric acid and perform a first hydrothermal reaction to obtain a first hydrothermal product, and then mix the first hydrothermal product with potassium hydroxide and perform a second hydrothermal reaction to obtain a second hydrothermal product; The dehydration module is used for adjusting the pH of the second hydrothermal product by phosphoric acid, and making potassium in the liquid phase react with the phosphoric acid to generate potassium phosphate compounds, and then low-temperature dehydration is carried out at 55-80 DEG C to obtain an oil-solid mixture, so that humic acid, phosphorus and potassium are retained in the solid phase. The cleaning module is used for dissolving the oil in the oil-solid mixture and obtaining a solid product by solid-liquid separation. The discharging module is used for drying the solid product to obtain an organic-inorganic compound fertilizer, which comprises hydrothermal carbon and humic acid and potassium phosphate compounds loaded in the pores of the hydrothermal carbon, so as to achieve a slow-release effect.

[0011] Compared with the prior art, the above technical scheme conceived by the present application considers low-carbon, energy-saving and emission-reducing of the system at the raw material input stage, and uses acid and alkali raw materials containing phosphorus and potassium to replace raw materials containing chlorine, sulfur and sodium. In addition, due to the optimization of the connection mode of the modules in the system, the pH of the second hydrothermal product is first adjusted by phosphoric acid to make potassium in the liquid phase react with the phosphoric acid to generate potassium phosphate compounds, and then low-temperature dehydration is carried out to realize solid-liquid separation, so as to avoid the loss of humic acid in the liquid phase and ensure that phosphorus and potassium are retained in the solid phase, thereby effectively improving the yield of humic acid and the utilization rate of phosphorus and potassium. At the same time, the organic-inorganic compound fertilizer prepared by the system comprises hydrothermal carbon and humic acid and potassium phosphate compounds loaded in the pores of the hydrothermal carbon, which can play a slow-release role and effectively improve the utilization rate of the fertilizer.

[0012] As a further preferred, the hydrothermal module comprises a feeding assembly, an acid reactor and an alkali reactor, the feeding assembly is connected with the inlet of the acid reactor, and the acid reactor is provided with a phosphoric acid inlet for mixing the biomass raw material with the phosphoric acid and carrying out a first-stage hydrothermal reaction to obtain a first hydrothermal product; the outlet of the acid reactor is connected with the inlet of the alkali reactor, and the alkali reactor is provided with a potassium hydroxide inlet for mixing the first hydrothermal product with the potassium hydroxide and carrying out a second-stage hydrothermal reaction to obtain a second hydrothermal product.

[0013] As a further preferred, the dehydration module comprises a first heat exchanger, a balance tank and a first vacuum distiller, the inlet of the first heat exchanger is connected with the outlet of the hydrothermal module, and the outlet is connected with the inlet of the balance tank, so as to cool the second hydrothermal product and send it into the balance tank; the balance tank is provided with a phosphoric acid inlet for adding phosphoric acid to adjust the pH of the second hydrothermal product; the inlet of the first vacuum distiller is connected with the outlet of the balance tank, and the solid outlet is connected with the cleaning module, so as to carry out low-temperature dehydration on the second hydrothermal product after the pH adjustment, and send the oil-solid mixture into the cleaning module.

[0014] As a further preferred, the cleaning module comprises a homogenizing tank, an extraction tube and a solid-liquid separator, the inlet of the homogenizing tank is connected with the solid outlet of the dewatering module, the outlet thereof is connected with the solid-liquid separator through the extraction tube, and the homogenizing tank is provided with a washing liquid inlet for adding washing liquid and dissolving oil in the oil-solid mixture in the extraction tube for cleaning, and then sending into the solid-liquid separator for solid-liquid separation; the solid outlet of the solid-liquid separator is connected with the discharging module to send the solid product into the discharging module.

[0015] As a further preferred, the cleaning module further comprises a second reduced pressure distiller and a combustion furnace, the inlet of the second reduced pressure distiller is connected with the liquid outlet of the solid-liquid separator, the outlet of the second reduced pressure distiller is connected with the homogenizing tank and the combustion furnace respectively, for separating the washing liquid and the oil in the liquid product, and sending into the homogenizing tank and the combustion furnace respectively; and the combustion furnace is further connected with the gas outlet of the balance tank for burning the hydrothermal combustible gas product.

[0016] As a further preferred, the dewatering module further comprises a second heat exchanger and an oil-water separator, the inlet of the second heat exchanger is connected with the gas outlet of the first reduced pressure distiller, the outlet of the second heat exchanger is connected with the oil-water separator, so as to cool the gas product by the second heat exchanger and separate oil and water by the oil-water separator; the oil outlet of the oil-water separator is connected with the combustion furnace.

[0017] As a further preferred, the discharging module comprises a drying machine and a granulator, the inlet of the drying machine is connected with the solid outlet of the cleaning module, the outlet thereof is connected with the granulator, for removing the washing liquid on the surface of the solid product and sending into the granulator for granulation.

[0018] Overall, compared with the prior art, the above technical scheme conceived by the present application mainly has the following technical advantages: 1. The present application utilizes phosphoric acid and potassium hydroxide for two-stage reaction of biomass raw materials, which can avoid introducing elements such as chlorine and sodium that are not friendly to the environment, and the introduced phosphorus and potassium elements can be directly converted into nutrients, effectively improving production efficiency and reducing production cost, and in order to avoid the loss of humic acid, phosphorus elements and potassium elements, the present application proposes a process path of adjusting pH first and then low-temperature dewatering, which can utilize the reaction of phosphoric acid and potassium in the liquid phase to generate potassium phosphate compounds and retain them in the solid phase, and on the other hand, it can avoid the pyrolysis of humic acid, effectively improving the yield of humic acid. The process can load humic acid and potassium phosphate compounds into the pores of hydrothermal carbon to play a slow-release role, effectively improving the utilization rate of fertilizer; 2. Meanwhile, the system provided by the application can extract humic acid first and then dehydrate at low temperature to realize solid-liquid separation, thereby avoiding loss of humic acid in the liquid phase and ensuring that phosphorus elements and potassium elements remain in the solid phase, effectively improving the yield of humic acid and the utilization rate of phosphorus and potassium, effectively shortening the production cycle of organic-inorganic compound fertilizers, and being suitable for large-scale industrial production. Meanwhile, the organic-inorganic compound fertilizer prepared by the system includes hydrothermal carbon and humic acid and potassium phosphate compounds loaded in the pores of the hydrothermal carbon, and can play a slow-release role and effectively improve the utilization rate of the fertilizer. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a schematic diagram of a system for continuously preparing organic-inorganic compound fertilizers from biomass provided by an embodiment of the application.

[0020] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: I - hydrothermal module, II - dehydration module, III - washing module, IV - discharge module, 1 - raw material feeding assembly, 2 - acid reactor, 3 - alkali reactor, 4 - first heat exchanger, 5 - balance tank, 6 - first vacuum distiller, 7 - screw conveyor, 8 - homogenizing tank, 9 - second heat exchanger, 10 - extraction tube, 11 - solid-liquid separator, 12 - second vacuum distiller, 13 - combustion furnace, 14 - oil-water separator, 15 - dryer, 16 - granulator. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the application more clear and understandable, the application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0022] The application provides a method for continuously preparing organic-inorganic compound fertilizers from biomass, which specifically comprises: S1 mixing the biomass raw material with phosphoric acid and performing first-stage hydrothermal reaction to obtain a first hydrothermal product; S2 after the acid reaction is completed, mixing the first hydrothermal product with potassium hydroxide and performing second-stage hydrothermal reaction to obtain a second hydrothermal product; S3 adjusting the pH of the second hydrothermal product with phosphoric acid so that potassium in the liquid phase reacts with the phosphoric acid to generate potassium phosphate compounds such as potassium dihydrogen phosphate, and then performing low-temperature dehydration at 55℃-80℃ to obtain an oil-solid mixture. In the prior art, the hydrothermal reaction is usually followed by solid-liquid separation and then adjustment of pH to precipitate humic acid. However, considering that the liquid phase contains K +A reaction occurs to obtain potassium dihydrogen phosphate and other potassium phosphate compounds, which are then dehydrated at low temperature (to avoid destroying the structure of the organic matter) to leave them in the solid phase, thereby retaining phosphorus and potassium elements in the solid phase. At the same time, this application does not perform solid-liquid separation, but only removes water by low-temperature dehydration, thereby enabling humic acid and potassium dihydrogen phosphate and other potassium phosphate compounds to be loaded in the pores of hydrothermal carbon to achieve a slow release effect, effectively improving the utilization rate of fertilizers; S4 performs oil-solid separation on the oil-solid mixture to prepare an organic-inorganic compound fertilizer.

[0023] The present application utilizes phosphoric acid and potassium hydroxide to carry out two-stage hydrothermal reaction, which can avoid introducing other elements while adding phosphorus and potassium, thereby not needing to increase the dechlorination and sodium removal link, and not needing to add additional inorganic components, effectively reducing production costs. At the same time, the present application first uses phosphoric acid to adjust the pH of the second hydrothermal product so that the potassium in the liquid phase reacts with phosphoric acid to generate potassium phosphate compounds such as potassium dihydrogen phosphate, and then dehydrates at low temperatures to achieve solid-liquid separation, which can avoid the loss of humic acid in the liquid phase and ensure that phosphorus and potassium elements are retained in the solid phase, thereby effectively improving the yield of humic acid and the utilization rate of phosphorus and potassium, and the present application provides a new method for preparing fertilizer using biomass, which can load humic acid and potassium phosphate compounds such as potassium dihydrogen phosphate in the pores of hydrothermal carbon to play a slow-release effect, effectively improving the utilization rate of fertilizer.

[0024] Furthermore, the temperature of the first hydrothermal reaction and the second hydrothermal reaction is 130°C to 220°C.

[0025] Further, in step S3, the pH of the second hydrothermal product is adjusted to 4-5 by adding phosphoric acid, and K + A reaction occurs to produce potassium phosphate compounds such as potassium dihydrogen phosphate. Too high or too low a pH value will have an adverse effect on the soil.

[0026] Furthermore, in step S4, a washing liquid such as dichloromethane is used to dissolve the oil in the oil-solid mixture and solid-liquid separation is performed to obtain a solid product, and then the washing liquid on the surface of the solid product is removed to obtain an organic-inorganic compound fertilizer, and the removed washing liquid can be recycled.

[0027] Furthermore, the hydrothermal combustible gas product generated during the low-temperature dehydration process can be burned, and the separated oil can also be burned to provide self-heating for the system.

[0028] like Figure 1 As shown, according to another aspect of the present application, a system for continuously producing organic-inorganic compound fertilizer from biomass is provided, the system comprising a hydrothermal module I, a dehydration module II, a cleaning module III and a discharging module IV, wherein: The hydrothermal module I is used for mixing the biomass raw material with phosphoric acid and performing a first-stage hydrothermal reaction to obtain a first hydrothermal product, and then mixing the first hydrothermal product with potassium hydroxide and performing a second-stage hydrothermal reaction to obtain a second hydrothermal product; The dehydration module II is used for adjusting the pH of the second hydrothermal product by using phosphoric acid so that potassium in the liquid phase reacts with phosphoric acid to generate potassium dihydrogen phosphate and other potassium phosphate compounds, and then performing low-temperature dehydration at 55-80°C to obtain an oil-solid mixture, and making phosphates and potassium elements remain in the solid phase; The cleaning module III is used for dissolving oil in the oil-solid mixture and obtaining a solid product through oil-solid separation; The discharging module IV is used for removing residual washing liquid such as dichloromethane on the surface of the solid product to obtain an organic-inorganic compound fertilizer.

[0029] The present application optimizes the connection mode of the modules in the system, can first adjust the pH of the second hydrothermal product by using phosphoric acid so that potassium in the liquid phase reacts with phosphoric acid to generate potassium dihydrogen phosphate and other potassium phosphate compounds, and then performs low-temperature dehydration to realize solid-liquid separation, thereby avoiding loss of humic acid in the liquid phase and ensuring that phosphorus elements and potassium elements remain in the solid phase, and further effectively improving the yield of humic acid and the utilization rate of phosphorus and potassium. At the same time, unlike the prior art of extracting humic acid from the liquid phase to prepare a fertilizer, the present application uses a low-temperature dehydration method to load humic acid and potassium dihydrogen phosphate and other potassium phosphate compounds in the pores of the hydrothermal carbon, thereby preparing an organic-inorganic compound fertilizer with a slow-release effect, which can effectively improve the utilization rate of the fertilizer, and realize continuous and efficient production of the fertilizer.

[0030] Further, the hydrothermal module I includes a feeding assembly 1, an acid reactor 2 and an alkali reactor 3, the feeding assembly 1 is connected with the inlet of the acid reactor 2, and the acid reactor 2 is provided with a phosphoric acid inlet, which is used for mixing the biomass raw material with phosphoric acid and performing a first-stage hydrothermal reaction to obtain a first hydrothermal product; the outlet of the acid reactor 2 is connected with the inlet of the alkali reactor 3, and the alkali reactor 3 is provided with a potassium hydroxide inlet, which is used for mixing the first hydrothermal product with potassium hydroxide and performing a second-stage hydrothermal reaction to obtain a second hydrothermal product.

[0031] Further, the dehydration module II includes a first heat exchanger 4, a balance tank 5 and a first vacuum distiller 6, the inlet of the first heat exchanger 4 is connected with the outlet of the alkali reactor 3, and the outlet is connected with the inlet of the balance tank 5, so as to cool the second hydrothermal product and send it into the balance tank 5; the balance tank 5 is provided with a phosphoric acid inlet, which is used for adding phosphoric acid to adjust the pH of the second hydrothermal product; the inlet of the first vacuum distiller 6 is connected with the outlet of the balance tank 5, and the solid outlet thereof is connected with the cleaning module III through a spiral conveyor 7, so as to perform low-temperature dehydration on the second hydrothermal product after the pH adjustment, and send the oil-solid mixture into the cleaning module III.

[0032] More preferably, the dewatering module II further comprises a second heat exchanger 9 and an oil-water separator 14, the inlet of the second heat exchanger 9 is connected with the gas outlet of the first pressure-reducing distiller 6, and the outlet is connected with the oil-water separator 14, so as to cool the gas product by the second heat exchanger 9 and separate the oil and water by the oil-water separator 14.

[0033] Further, the cleaning module III comprises a homogenizing tank 8, an extraction tube 10 and a solid-liquid separator 11, the inlet of the homogenizing tank 8 is connected with the solid outlet of the dewatering module II, and the outlet is connected with the solid-liquid separator 11 through the extraction tube 10, and the homogenizing tank 8 is provided with a washing liquid inlet for adding the washing liquid and mixing the washing liquid with the oil-solid mixture, and the oil in the oil-solid mixture is further dissolved in the extraction tube 10 for cleaning, and then the oil-solid mixture is sent into the solid-liquid separator 11 for solid-liquid separation; the solid outlet of the solid-liquid separator 11 is connected with the discharging module IV, so as to send the solid product into the discharging module IV.

[0034] Further, the cleaning module III further comprises a second pressure-reducing distiller 12 and a combustion furnace 13, the inlet of the second pressure-reducing distiller 12 is connected with the liquid outlet of the solid-liquid separator 11, and the outlet of the second pressure-reducing distiller 12 is connected with the homogenizing tank 8 and the combustion furnace 13 respectively, so as to separate the washing liquid and the oil in the liquid product, and send them into the homogenizing tank 8 and the combustion furnace 13 respectively, so as to achieve the purposes of recycling the washing liquid and utilizing the oil phase heat value; meanwhile, the combustion furnace 13 is further connected with the gas outlet of the balance tank 5 and the oil outlet of the oil-water separator 14, so as to burn the water heat combustible gas product and the oil, so as to supply heat for the system.

[0035] Further, the discharging module IV comprises a drying machine 15 and a granulator 16, the inlet of the drying machine 15 is connected with the solid outlet of the cleaning module III, and the outlet is connected with the granulator 16, so as to remove the washing liquid such as dichloromethane on the surface of the solid product and send it into the granulator 16 for granulation.

[0036] The technical scheme provided by the present application is further described below according to specific embodiments.

[0037] Embodiment 1 S1 biomass enters the acid reactor 2 through the raw material feeding assembly 1, and phosphoric acid is added into the acid reactor 2 to make the pH be 1, so as to carry out the first stage hydrothermal reaction, the reactor temperature is 180℃, and the residence time is 4h, so as to be suitable for the generation of the precursor of humic acid; S2 after the first stage hydrothermal reaction is completed, the first hydrothermal product is sent into the alkali reactor 3, and potassium hydroxide is added into the alkali reactor 3 to make the pH be 14, so as to carry out the second stage hydrothermal reaction, the reactor temperature is 180℃, and the residence time is 4h, so as to be suitable for the synthesis of humic acid from the precursor of humic acid; S3 After the second hydrothermal reaction is completed, the second hydrothermal product is cooled by the first heat exchanger 4 and then sent to the balance tank 5, phosphoric acid is added to make the pH value 4, and the discharged hydrothermal combustible gas product is sent to the combustion furnace 13, and the solid-liquid mixture is sent to the first pressure-reducing distiller 6; the solid-liquid mixture is separated at 55℃ in the first pressure-reducing distiller 6, the separated steam is cooled by the second heat exchanger 9 and then enters the oil-water separator 14, the separated solid phase is sent to the homogenate tank 8, and the water and oil separated by the oil-water separator 14 are discharged; S4 Dichloromethane is added to the homogenate tank 8, mixed uniformly, enters the extraction tube 10 to clean the residual oil on the surface of the solid, then enters the solid-liquid separator 11, the separated solid enters the drying machine 15, and the liquid enters the second pressure-reducing distiller 12; the oil separated by the second pressure-reducing distiller 12 enters the combustion furnace 13, and the dichloromethane enters the homogenate tank 8 for recycling; the surface residual dichloromethane of the solid product is removed in the drying machine 15 and reused; the dried solid product is sent to the granulator 16 to be granulated and discharged to prepare the organic-inorganic compound fertilizer.

[0038] Example 2 The same as example 1, only the low-temperature dehydration temperature in step S3 is 80℃, and the pH value is 5, and finally the organic-inorganic compound fertilizer is prepared, which includes hydrothermal carbon and humic acid and potassium dihydrogen phosphate and other potassium phosphate compounds loaded in the pores of the hydrothermal carbon.

[0039] Example 3 The same as example 1, only the low-temperature dehydration temperature in step S3 is 60℃, and the pH value is 5, and finally the organic-inorganic compound fertilizer is prepared, which includes hydrothermal carbon and humic acid and potassium dihydrogen phosphate and other potassium phosphate compounds loaded in the pores of the hydrothermal carbon.

[0040] Example 4 The same as example 1, only the low-temperature dehydration temperature in step S3 is 75℃, and finally the organic-inorganic compound fertilizer is prepared, which includes hydrothermal carbon and humic acid and potassium dihydrogen phosphate and other potassium phosphate compounds loaded in the pores of the hydrothermal carbon.

[0041] In the description of the present application, it should be understood that the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0042] Those skilled in the art can understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for continuously producing organic-inorganic compound fertilizer from biomass, characterized in that: Specifically: S1: mixing a biomass raw material with phosphoric acid and performing a first hydrothermal reaction to obtain a first hydrothermal product; S2: mixing the first hydrothermal product with potassium hydroxide and performing a second hydrothermal reaction to obtain a second hydrothermal product; S3: adjusting the pH of the second hydrothermal product with phosphoric acid and reacting potassium in the liquid phase with the phosphoric acid to form potassium phosphate compounds, followed by low-temperature dehydration at 55° C. to 80° C. to obtain an oil-solid mixture, so that humic acid, phosphorus, and potassium remain in the solid phase; S4 performs oil-solid separation on the oil-solid mixture to prepare an organic-inorganic compound fertilizer, wherein the organic-inorganic compound fertilizer includes hydrochar and humic acid and potassium phosphate compounds loaded in the pores of the hydrochar, thereby achieving a slow-release effect.

2. The method according to claim 1, wherein The temperature of the first hydrothermal reaction and the second hydrothermal reaction is 130°C to 220°C.

3. The method according to claim 1, wherein In step S3, the pH of the second hydrothermal product is adjusted to 4-5.

4. The method according to any one of claims 1 to 3, wherein In step S4, the washing liquid is used to dissolve the oil in the oil-solid mixture and perform solid-liquid separation to obtain a solid product, and then the washing liquid on the surface of the solid product is removed to obtain an organic-inorganic compound fertilizer.

5. A system for continuously producing organic-inorganic compound fertilizer from biomass, characterized in that: It includes a hydrothermal module (I), a dehydration module (II), a cleaning module (III) and a discharging module (IV), wherein: The hydrothermal module (I) is used to mix the biomass feedstock with phosphoric acid and perform a first hydrothermal reaction to obtain a first hydrothermal product, and then mix the first hydrothermal product with potassium hydroxide and perform a second hydrothermal reaction to obtain a second hydrothermal product; The dehydration module (II) is used to adjust the pH of the second hydrothermal product using phosphoric acid and react potassium in the liquid phase with phosphoric acid to form potassium phosphate compounds, and then dehydrate at a low temperature of 55°C to 80°C to obtain an oil-solid mixture, so that humic acid, phosphorus and potassium elements are retained in the solid phase; The cleaning module (III) is used to dissolve the oil in the oil-solid mixture and obtain a solid product through solid-liquid separation; The discharging module (IV) is used to dry the solid product to obtain an organic-inorganic compound fertilizer, which includes hydrothermal carbon and humic acid and potassium phosphate compounds loaded in the pores of the hydrothermal carbon, thereby achieving a slow-release effect.

6. The system according to claim 5, wherein: The hydrothermal module (I) comprises a feed assembly (1), an acid reactor (2) and an alkaline reactor (3), wherein the feed assembly (1) is connected to the inlet of the acid reactor (2), and the acid reactor (2) is provided with a phosphoric acid inlet for mixing the biomass raw material with phosphoric acid and performing a first hydrothermal reaction to obtain a first hydrothermal product; the outlet of the acid reactor (2) is connected to the inlet of the alkaline reactor (3), and the alkaline reactor (3) is provided with a potassium hydroxide inlet for mixing the first hydrothermal product with potassium hydroxide and performing a second hydrothermal reaction to obtain a second hydrothermal product, and / or, The dehydration module (II) comprises a first heat exchanger (4), a balancing tank (5) and a first vacuum distiller (6); the inlet of the first heat exchanger (4) is connected to the outlet of the hydrothermal module (I), and the outlet is connected to the inlet of the balancing tank (5) so as to cool the second hydrothermal product and send it to the balancing tank (5); the balancing tank (5) is provided with a phosphoric acid inlet for adding phosphoric acid to adjust the pH of the second hydrothermal product; the inlet of the first vacuum distiller (6) is connected to the outlet of the balancing tank (5), and the solid outlet thereof is connected to the cleaning module (III) so as to perform low-temperature dehydration on the second hydrothermal product after pH adjustment and send the oil-solid mixture to the cleaning module (III).

7. The system according to claim 6, wherein: The cleaning module (III) includes a homogenizing tank (8), an extraction tube (10) and a solid-liquid separator (11). The inlet of the homogenizing tank (8) is connected to the solid outlet of the dehydration module (II), and the outlet is connected to the solid-liquid separator (11) through the extraction tube (10). At the same time, the homogenizing tank (8) is provided with a washing liquid inlet for adding washing liquid and dissolving the oil in the oil-solid mixture in the extraction tube (10) for washing, and then sending it to the solid-liquid separator (11) for solid-liquid separation; the solid outlet of the solid-liquid separator (11) is connected to the discharge module (IV) to send the solid product to the discharge module (IV).

8. The system according to claim 7, wherein: The cleaning module (III) further includes a second vacuum distiller (12) and a combustion furnace (13), wherein the inlet of the second vacuum distiller (12) is connected to the liquid outlet of the solid-liquid separator (11), and the outlet of the second vacuum distiller (12) is connected to the homogenization tank (8) and the combustion furnace (13), respectively, for separating the washing liquid and the oil in the liquid product and feeding them into the homogenization tank (8) and the combustion furnace (13), respectively; at the same time, the combustion furnace (13) is also connected to the gas outlet of the balancing tank (5) for burning the hydrothermal combustible gas product.

9. The system according to claim 8, wherein The dehydration module (II) further includes a second heat exchanger (9) and an oil-water separator (14), wherein the inlet of the second heat exchanger (9) is connected to the gas outlet of the first vacuum distiller (6), and the outlet of the second heat exchanger (9) is connected to the oil-water separator (14), so that the gas product is cooled by the second heat exchanger (9) and the oil-water separator (14) is used to separate oil and water; the oil outlet of the oil-water separator (14) is connected to the combustion furnace (13).

10. The system according to any one of claims 5 to 9, characterized in that: The discharge module (IV) includes a dryer (15) and a granulator (16). The inlet of the dryer (15) is connected to the solid outlet of the cleaning module (III), and the outlet is connected to the granulator (16). The dryer is used to clean and dry the solid product and send it to the granulator (16) for granulation.

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