Device for preparing fulvic acid through hydrothermal reaction of wet garbage

Abstract

The utility model discloses a device for preparing fulvic acid through hydrothermal reaction of wet garbage. The device comprises a hydrothermal reaction unit, a solid fulvic acid production unit, a biodiesel separation unit and a concentration and evaporation unit, the hydrothermal reaction is divided into four stages, relatively simple control parameters can be set in the industrialization process, and personnel operation and monitoring are facilitated. Even if a problem occurs in a certain stage, related problems can be quickly solved according to parameter requirements. In the concentration and evaporation stage, the temperature rise amplitude of the low-concentration fulvic acid liquid is controlled through two-stage heating, and energy consumption in the operation process is reduced. Heat sources (hot water and steam) in the concentration and evaporation stage can be used for front-end material slurry preparation and steam type drying machines and heating of low-concentration fulvic acid, use of additional heat sources is reduced, and investment cost of equipment (steam generator) in the construction process and subsequent operation cost are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of garbage disposal, and more particularly to a device for preparing fulvic acid through hydrothermal reaction of wet garbage. Background Art

[0002] Wet garbage refers to garbage generated in residents' daily lives and in activities such as food processing, catering services, and unit meals. It has the characteristics of high water content and high organic matter content, is easy to rot and produce foul odors, posing a threat to the urban living environment and residents' health.

[0003] According to the differences in actual treatment plants' collection systems and the composition characteristics of garbage, wet garbage is divided into two categories: kitchen waste and catering waste.

[0004] Kitchen waste refers to sorted kitchen waste and fruit peels generated in residential areas and markets. According to a survey of waste characteristics, after mandatory waste sorting was implemented, the bulk density and moisture content of dry waste decreased by approximately 36.80% and 36.33%, respectively, while the low-calorific value of dry waste increased by approximately 103.60%. Furthermore, the composition of kitchen waste changed significantly, with a significant decrease in impurities, a significant increase in bulk density by approximately 235.56%, and a 37.11% increase in moisture content to approximately 80%.

[0005] Catering waste refers to food residues and food processing waste generated from food processing, catering services, unit catering and other activities outside of residents' daily lives. Catering waste is mainly composed of organic substances such as starch, dietary fiber, animal fat, etc., and has the characteristics of high water content, high oil and salt content, easy to ferment and stinky. Generally, the moisture content of catering waste is relatively high, basically around 85%; the impurity content varies greatly (1.97% to 32.85%), but shows a trend of less impurities in winter and spring and more impurities in summer; the C / N ratio is low, maintaining an average of around 15; the organic matter content is relatively high, basically maintaining an average of 85%.

[0006] The current key points and difficulties in wet garbage disposal include:

[0007] 1. The oil content in kitchen waste increases

[0008] With the widespread adoption of waste sorting, the moisture and oil content of food waste has increased. If anaerobic digestion is used without removing grease, this grease will enter the anaerobic process along with the food waste slurry, leading to the accumulation of volatile fatty acids (VFAs) in the anaerobic process and affecting the stable operation of the anaerobic system.

[0009] 2. The carbon-nitrogen ratio of the biogas liquid is unbalanced after dehydration of the biogas residue, making it difficult to treat.

[0010] After the sludge is dehydrated, the biogas liquid enters the sewage treatment system. If the utilization rate of anaerobic organic matter in the previous stage is high, the carbon-nitrogen ratio of the biogas liquid will be unbalanced, making sewage treatment more difficult.

[0011] 3. Odor control is the key

[0012] Odor control in a wet waste treatment plant is a key indicator of successful project operation. Odor control should focus on two aspects: front-end collection and end-of-life treatment.

[0013] The complexity of wet waste composition currently makes it difficult to achieve efficient and high-value treatment and utilization using a single existing treatment technology. Therefore, one development approach is to separate wet waste components and integrate multiple treatment and utilization technologies. Utility Model Content

[0014] In view of this, the utility model provides a device for preparing fulvic acid through hydrothermal reaction of wet garbage to solve the technical problems encountered in the background technology.

[0015] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0016] A device for preparing fulvic acid by hydrothermal reaction of wet garbage, comprising: a hydrothermal reaction unit, a solid fulvic acid production unit, a biodiesel separation unit and a concentration evaporation unit;

[0017] The hydrothermal reaction unit includes: a slurry mixing barrel, a slurry mixing pump, a hydrothermal reactor, a thermal oil heating device and a flash tank;

[0018] The slurry preparation barrel, slurry preparation pump, hydrothermal reactor and flash tank are connected in sequence;

[0019] The thermal oil heating device is cyclically connected to the hydrothermal reactor;

[0020] A bypass is provided on the pipelines connecting the thermal oil heating device and the inlet and outlet of the hydrothermal reactor.

[0021] In the present invention, the slurry mixing barrel has two layers, the inner layer is the material stirring unit, and the outer layer is the heating unit;

[0022] The hydrothermal reactor is equipped with a jacket, which is a sealed space surrounding the outside of the reactor. The temperature inside the reactor is controlled by circulating a heating or cooling medium in the jacket.

[0023] The discharge port at the bottom of the reactor is connected to the inlet of the flash tank. Three electric valves are installed on the pipeline, namely the electric on-off valve, the electric regulating valve, and the electric on-off valve. When the hydrothermal reactor is heating and reacting, all three valves are closed. After the heat preservation and pressure maintenance are completed, the two electric valves are opened first, and then the electric regulating valve is slowly opened (initial opening 15°, then 30°, 50°, 75°, 90°) to evenly discharge the reacted materials into the flash tank. This makes the amount of steam generated in the flash tank relatively uniform, and can continuously and stably provide heat for the subsequent process (steam dryer).

[0024] The pressure relief port at the top of the reactor is also connected to the feed port of the flash tank. Three electric valves are also installed on the pipeline: an electric on-off valve, an electric regulating valve, and an electric on-off valve. When overpressure and overtemperature occur in the reactor, the two electric on-off valves are opened first, and then the electric regulating valve is slowly opened (initial opening 5°, up to 15°) to release the pressure. When the pressure is lower than the saturated vapor pressure at the current temperature, the valve is closed and the reaction continues. If overpressure occurs three times in a row, heating is stopped, the temperature is lowered and the material is unloaded, and the hydrothermal reaction is considered a failure.

[0025] The hydrothermal reactor jacket is equipped with a thermal oil inlet and outlet. Electric regulating valves are installed on the pipelines connecting the thermal oil heater to the inlet and outlet. A bypass line is provided between the two electric regulating valves and the thermal oil heater, also equipped with an electric regulating valve. When the hydrothermal reactor is being charged, the electric regulating valves connecting the thermal oil heater to the inlet and outlet are closed, and the electric regulating valve in the bypass line is fully opened to verify that the thermal oil heater's delivery pump and heating unit are functioning properly (primarily to prevent coked thermal oil from clogging the pipelines and adhering to the heater's tank walls, slowing the temperature rise). If the temperature rises quickly to 50°C, the thermal oil heater is operating normally. If the temperature rises too slowly, check and decide whether to drain all the thermal oil and let it settle (clear thermal oil from the top should still be added to the thermal oil heater) and clean the heater and pipelines. When the reactor enters the pressure and temperature holding stage, the electric regulating valve on the pipe connecting the thermal oil heating device and the reactor jacket is adjusted down (opening ≤ 30°), the electric regulating valve on the bypass line is opened (opening 60°~90°), and the heating unit of the thermal oil is turned off. The temperature of the hydrothermal reactor is maintained within the set range by circulating most of the thermal oil internally. When the reactor is finished with temperature and pressure holding, the electric regulating valve on the pipe connecting the thermal oil heating device and the reactor jacket is turned off, and the electric regulating valve on the bypass line is fully opened. The thermal oil is cooled by circulating all of the internal circulation to avoid heat accumulation or coking in the closed or piped area caused by static cooling of the thermal oil.

[0026] Preferably, the solid fulvic acid production unit comprises: a centrifuge, a steam dryer, and a granulator;

[0027] The flash tank is connected to the centrifuge, the steam dryer and the granulator in sequence.

[0028] Preferably, the biodiesel separation unit comprises: a static stratification tank, a grease storage tank, a grease feed pump, an oil-water separator and a biodiesel dehydrator;

[0029] The centrifuge is connected with the static stratification tank, the grease storage tank, the grease feed pump, the oil-water separator and the biodiesel dehydrator in sequence.

[0030] Preferably, the concentration and evaporation unit comprises: a low-concentration fulvic acid storage tank, a fulvic acid feed pump, a preheating plate heat exchanger, a secondary heating plate heat exchanger, a forced circulation pump, a shell and tube heat exchanger, an evaporator, a vacuum buffer tank, a vacuum pump, a steam generator, a secondary defoamer, a steam compressor, a discharge pump, a high-concentration liquid fulvic acid storage tank, a condensate storage tank, a drainage pump and a condensate plate heat exchanger;

[0031] The static stratification tank is connected to the low-concentration fulvic acid storage tank, the fulvic acid feed pump, the preheating plate heat exchanger, the secondary heating plate heat exchanger, the forced circulation pump, the shell and tube heat exchanger, and the evaporator in sequence;

[0032] One end of the preheating plate heat exchanger is also connected to the flash tank, and the other end is connected to the vacuum buffer tank, the vacuum pump, the secondary heating plate heat exchanger, and the steam dryer in sequence;

[0033] One end of the steam generator is connected to the pipeline between the vacuum pump and the secondary temperature-raising plate heat exchanger, and the other end is connected to the shell and tube heat exchanger;

[0034] The secondary defoamer is cyclically connected to the evaporator;

[0035] One end of the steam compressor is connected to the secondary demister, and the other end is connected to the pipeline between the steam generator and the shell and tube heat exchanger;

[0036] The evaporator is also connected to the discharge pump and the high-concentration liquid fulvic acid storage tank in sequence;

[0037] The shell and tube heat exchanger is also connected to the condensate plate heat exchanger, the condensate storage tank, the drainage pump, and the slurry mixing barrel in sequence;

[0038] The condensed water storage tank is also connected to the vacuum buffer tank.

[0039] In this utility model, the secondary demister uses corrugated wire mesh structured packing to trap foam and water droplets. This packing is made of 0.5mm-diameter wire mesh folded at a regular angle (30-45°). This packing features thin walls, a high porosity, high flux, light weight, low resistance, a small, regular gas phase channel angle, sufficient gas contact, excellent separation, high efficiency, and low pressure drop. Small holes in the corrugated wire mesh sheets enhance uniform liquid distribution and liquid film renewal, reduce dead spots in the packing, and increase separation efficiency.

[0040] The metal wire mesh corrugated structured packing is easy to disassemble, clean and replace. Depending on the usage, multi-layer metal wire mesh corrugated structured packing can also be used (single-layer packing thickness 50mm, maximum 5 layers).

[0041] Preferably, an electric regulating valve is provided between the inlet pipeline and the outlet pipeline of the steam compressor; the upper portion of the evaporator is an evaporation chamber, and the lower portion is a Y-shaped boiling chamber.

[0042] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. Multi-stage screening, separation and crushing can separate materials from debris more cleanly, avoiding some debris (plastic, glass, etc.) affecting the operation of equipment and the stability of hydrothermal process, and the relatively small and uniform particles react relatively fully in the hydrothermal reaction stage.

[0044] 2. Wet garbage can be fully utilized after hydrothermal reaction to obtain solid fulvic acid particles, high-concentration liquid fulvic acid and biomass diesel.

[0045] 3. The hydrothermal reaction is divided into four stages. During the industrialization process, relatively simple control parameters can be set, making it easier for operators to operate and monitor. Even if a problem occurs at a certain stage, it can be quickly resolved based on the parameter requirements.

[0046] 4. During the concentration and evaporation stage, two-stage heating is used to control the temperature rise of the low-concentration fulvic acid liquid, reducing energy consumption during operation. The heat source (hot water, steam) in the concentration and evaporation stage can be used for front-end material mixing and steam dryers, as well as to heat the low-concentration fulvic acid. This reduces the use of additional heat sources, equipment (steam generator) investment costs during construction, and subsequent operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0048] Figure 1 This is a structural diagram of the device of the utility model.

[0049] Among them, in the figure:

[0050] 1-slurry mixing barrel; 2-slurry mixing pump; 3-hydrothermal reactor; 31-pressure relief port; 32-discharge port; 33-thermal oil inlet; 34-thermal oil outlet; 4-thermal oil heating device; 5-flash tank; 6-centrifuge; 7-steam dryer; 8-granulator; 9-static stratification tank; 10-grease storage tank; 11-grease feed pump; 12-oil-water separator; 13-biodiesel dehydrator; 14-low concentration fulvic acid storage tank; 1 5-Fulvic acid feed pump; 16-Preheating plate heat exchanger; 17-Secondary heating plate heat exchanger; 18-Forced circulation pump; 19-Shell and tube heat exchanger; 20-Evaporator; 21-Vacuum buffer tank; 22-Vacuum pump; 23-Steam generator; 24-Secondary demister; 25-Steam compressor; 26-Discharge pump; 27-High-concentration liquid fulvic acid storage tank; 28-Condensate storage tank; 29-Drainage pump; 30-Condensate plate heat exchanger. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] Example 1

[0053] This embodiment provides a device for preparing fulvic acid by hydrothermal reaction of wet garbage, characterized by comprising: a hydrothermal reaction unit, a solid fulvic acid production unit, a biodiesel separation unit and a concentration and evaporation unit;

[0054] The hydrothermal reaction unit includes: a slurry mixing barrel 1, a slurry mixing pump 2, a hydrothermal reactor 3, a thermal oil heating device 4 and a flash tank 5;

[0055] The slurry mixing barrel 1, the slurry mixing pump 2, the hydrothermal reactor 3, and the flash tank 5 are connected in sequence;

[0056] The thermal oil heating device 4 is cyclically connected to the hydrothermal reactor 3;

[0057] The hydrothermal reactor 3 is provided with a pressure relief port 31 and a discharge port 32, which are respectively connected to the flash tank 5;

[0058] An electric valve, an electric regulating valve and an electric valve are sequentially provided between the pressure relief port 31 and the flash tank 5 and between the discharge port 32 and the flash tank 5 .

[0059] The hydrothermal reactor 3 is further provided with a heat transfer oil inlet 33 and a heat transfer oil outlet 34; both the heat transfer oil inlet 33 and the heat transfer oil outlet 34 are connected to the heat transfer oil heating device;

[0060] Electric regulating valves are provided between the thermal oil heating device and the thermal oil inlet 33 and between the thermal oil heating device and the thermal oil outlet 34;

[0061] A bypass is provided between the two electric regulating valves and the thermal oil heating device, and an electric regulating valve is provided on the bypass.

[0062] The solid fulvic acid production unit includes: a centrifuge 6, a steam dryer 7, and a granulator 8;

[0063] The flash tank 5 is connected to the centrifuge 6, the steam dryer 7 and the granulator 8 in sequence.

[0064] The biodiesel separation unit includes: a static stratification tank 9, a grease storage tank 10, a grease feed pump 11, an oil-water separator 12 and a biodiesel dehydrator 13;

[0065] The centrifuge 6 is connected to the static stratification tank 9, the grease storage tank 10, the grease feed pump 11, the oil-water separator 12, and the biodiesel dehydrator 13 in sequence.

[0066] The concentration and evaporation unit includes: a low-concentration fulvic acid storage tank 14, a fulvic acid feed pump 15, a preheating plate heat exchanger 16, a secondary heating plate heat exchanger 17, a forced circulation pump 18, a shell and tube heat exchanger 19, an evaporator 20, a vacuum buffer tank 21, a vacuum pump 22, a steam generator 23, a secondary demister 24, a steam compressor 25, a discharge pump 26, a high-concentration liquid fulvic acid storage tank 27, a condensate storage tank 28, a drainage pump 29 and a condensate plate heat exchanger 30;

[0067] The static stratification tank 9 is connected to the low-concentration fulvic acid storage tank 14, the fulvic acid feed pump 15, the preheating plate heat exchanger 16, the secondary heating plate heat exchanger 17, the forced circulation pump 18, the shell and tube heat exchanger 19, and the evaporator 20 in sequence;

[0068] One end of the preheating plate heat exchanger 16 is also connected to the flash tank 5, and the other end is connected to the vacuum buffer tank 21, the vacuum pump 22, the secondary heating plate heat exchanger 17, and the steam dryer 7 in sequence;

[0069] One end of the steam generator 23 is connected to the pipeline between the vacuum pump 22 and the secondary heating plate heat exchanger 17, and the other end is connected to the shell and tube heat exchanger 19;

[0070] The secondary demister 24 is cyclically connected to the evaporator 20;

[0071] One end of the steam compressor 25 is connected to the secondary demister 24, and the other end is connected to the pipeline between the steam generator 23 and the shell and tube heat exchanger 19;

[0072] The evaporator 20 is also connected to a discharge pump 26 and a high-concentration liquid fulvic acid storage tank 27 in sequence;

[0073] The shell and tube heat exchanger 19 is also connected to the condensate plate heat exchanger 30, the condensate storage tank 28, the drainage pump 29, and the slurry mixing barrel 1 in sequence;

[0074] The condensed water storage tank 28 is also connected to the vacuum buffer tank 21 .

[0075] An electric regulating valve is provided between the inlet and outlet pipes of the steam compressor 25. The upper portion of the evaporator 20 is an evaporation chamber, and the lower portion is a Y-shaped boiling chamber.

[0076] Example 2

[0077] This embodiment provides a method for preparing fulvic acid by hydrothermal reaction of wet garbage using the above-mentioned device, comprising the following steps:

[0078] (1) The ground wet garbage material (particle size of about 0.1 to 1 mm) is introduced into the slurry mixing barrel 1, and clean water is added in proportion (material proportion 5%) and stirred to make the material uniformly dispersed in the aqueous solution. By injecting water at a certain temperature (≤40°C) into the heating jacket of the slurry mixing barrel 1, the material temperature reaches 30°C, and the heated slurry is transported to the hydrothermal reactor 3 through the slurry mixing pump 2;

[0079] The heated slurry is transported to the hydrothermal reactor 3 and stirred. Then the thermal oil heating device 4 is turned on. The thermal oil circulates in the jacket of the hydrothermal reactor to heat the material in the hydrothermal reactor 3. The material heating and insulation process can be divided into four stages:

[0080] The first stage: hydrolysis reaction stage, the reaction temperature is maintained at 40-75 ° C, the pressure in the reactor is ≤ 0.04 MPa, and the carbohydrates and proteins in the material mainly undergo hydrolysis reaction (macromolecules become small molecules, and are converted into oligomers and monomers represented by water-soluble organic matter such as organic acids, furans, and phenolic compounds);

[0081] The second stage: dehydration / decarboxylation and polymerization reaction, the reaction temperature is maintained at 80-125 ° C, at which time the pressure in the reactor is ≤ 0.23 MPa. In this stage, part of the hydrolysis product is dehydrated and decarboxylated, while part of the monomer undergoes polymerization reaction;

[0082] The third stage is the aromatization reaction, maintaining the reaction temperature at 160-200°C and the pressure in the reactor at 0.62-1.6 MPa. The polymer produces aromatic cluster compounds, but when their concentration reaches saturation, crystal nuclei are generated. Under the synergistic effect of diffusion and adsorption, the crystal nuclei gradually grow, and as the reaction proceeds, humic acid with a rich surface rich in active oxygen groups is formed (the main product is fulvic acid, accompanied by small amounts of palmitic acid, black humic acid, and low-carbon fusel alcohols);

[0083] The fourth stage: heat preservation and pressure holding stage, maintaining the temperature in the reactor at 190°C, the pressure at 1.3 MPa, and the heat preservation and pressure holding time at 50 minutes;

[0084] (2) After the hydrothermal reactor 3 is heated to completion, the valve on the pipeline from the hydrothermal reactor 3 to the flash tank 5 is opened, and the material is discharged into the flash tank 5 at a relatively uniform rate. At the moment the material slurry enters the flash tank 5, the low-boiling-point organic matter (methanol, ethanol, acetic acid, etc.) and part of the water are rapidly vaporized into steam. The steam is pumped to the preheating plate heat exchanger 16 by the vacuum pump 22 in the concentration evaporation unit, and heat is exchanged with the low-concentration fulvic acid delivered by the fulvic acid feed pump 15 in the concentration evaporation unit. The material at the bottom of the flash tank 5 enters the centrifuge 6 for solid-liquid separation, and the solid enters the steam dryer 7 and is dried by the steam of the secondary heating plate heat exchanger 17 in the concentration evaporation unit. The dried solid enters the granulator 8 for granulation, maintaining a certain particle size.

[0085] (3) The liquid from the centrifuge 6 enters the static stratification tank 9 and is left to stand for 2 to 4 hours. The upper layer of grease enters the subsequent grease storage tank 10. When the liquid level in the grease storage tank 10 reaches three-quarters, the grease in the grease storage tank 10 is transported to the oil-water separator 12 through the grease delivery pump 11 for oil-water separation. Most of the water is removed from the grease 12 (the water content of the grease is ≤1%), and then enters the biodiesel dehydrator 13 to further reduce the water content of the biodiesel (≤0.05%).

[0086] (4) The liquid at the bottom of the static stratification tank 9 enters the low-concentration fulvic acid storage tank 14 for temporary storage after static separation. When the liquid in the low-concentration fulvic acid storage tank 14 can keep the concentration evaporation unit running for more than 10 hours, the concentration evaporation unit is turned on. The fulvic acid feed pump 15 transports the low-concentration fulvic acid in the low-concentration fulvic acid storage tank 14 to the preheating plate heat exchanger 16 for heat exchange with the steam from the front-end flash tank 5. At this time, the steam from the flash tank 5 is sucked by the vacuum pump 22 and mixed with the new steam generated by the steam generator 23 to enter the secondary heating plate heat exchanger 17. When the steam from the flash tank 5 enters the vacuum buffer tank 21, the condensed water enters the condensed water storage tank 28 through the pipe at the bottom of the vacuum buffer tank 21 (the outlet end of the pipe is always kept under liquid to form a liquid seal). The low-concentration fulvic acid enters the secondary heating plate heat exchanger 17 for a second heating. The temperature increase is controlled. The steam from the secondary heating plate heat exchanger 17 enters the front-end steam dryer 7 for secondary utilization.

[0087] (5) The low-concentration fulvic acid after two heat exchanges enters the inlet of the forced circulation pump 18, and the outlet of the Y-shaped boiling chamber in the evaporator 20 is connected to the inlet of the forced circulation pump 18. The forced circulation pump 18 transports the liquid in the boiling chamber to the shell and tube heat exchanger 19, and the steam generated in the evaporation 20 is sucked by the steam compressor 25 and transported to the shell and tube heat exchanger 19, and heat is exchanged with the low-concentration fulvic acid transported by the forced circulation pump 18 in the shell and tube heat exchanger 19. At this time, the steam condenses in the shell and tube heat exchanger 19, and the condensate is heat-exchanged through the condensate plate heat exchanger 30 and enters the condensate storage tank 28. The drainage pump 29 transports the condensate to the slurry mixing barrel 1 as a heat source or slurry mixing water for the slurry mixing barrel 1;

[0088] (6) The concentration and evaporation unit continuously feeds and evaporates. When the fulvic acid concentration at the bottom of the evaporator 20 exceeds 40%, the discharge pump 26 is turned on to transport the liquid at the bottom of the evaporator to the high-concentration liquid fulvic acid storage tank 27 for cooling, thereby maintaining a balance between the discharge and the feed. When the fulvic acid concentration at the bottom of the evaporator is lower than 40%, the discharge pump 26 is turned off and evaporation and concentration are continued.

[0089] (7) A branch of the steam generator 23 is connected to the steam pipeline from the steam compressor 25 to the shell-and-tube heat exchanger 19. When the condensing and evaporating unit is first started and heated, the steam generated by the steam generator 23 is used to heat the condensing and evaporating unit. When the evaporation chamber produces sufficient steam, this branch can be closed or the steam supply can be reduced. The inlet and outlet pipes of the steam compressor 25 are connected to a bypass branch for quickly starting the centrifugal steam compressor. If a Roots steam compressor is selected, this bypass branch is not included.

[0090] Example 3

[0091] This embodiment provides a method for preparing fulvic acid by hydrothermal reaction of wet garbage using the above-mentioned device, comprising the following steps:

[0092] (1) The ground wet garbage material (particle size of about 0.1 to 1 mm) is introduced into the slurry mixing barrel 1, and clean water is added in proportion (material proportion 30%) and stirred to make the material uniformly dispersed in the aqueous solution. Water at a certain temperature (≤40°C) is injected into the heating jacket of the slurry mixing barrel 1 to make the material temperature reach 35°C. The heated slurry is transported to the hydrothermal reactor 3 through the slurry mixing pump 2;

[0093] The heated slurry is transported to the hydrothermal reactor 3 and stirred. Then the thermal oil heating device 4 is turned on. The thermal oil circulates in the jacket of the hydrothermal reactor to heat the material in the hydrothermal reactor 3. The material heating and insulation process can be divided into four stages:

[0094] The first stage: hydrolysis reaction stage, the reaction temperature is maintained at 40-75 ° C, the pressure in the reactor is ≤ 0.04 MPa, and the carbohydrates and proteins in the material mainly undergo hydrolysis reaction (macromolecules become small molecules, and are converted into oligomers and monomers represented by water-soluble organic matter such as organic acids, furans, and phenolic compounds);

[0095] The second stage: dehydration / decarboxylation and polymerization reaction, the reaction temperature is maintained at 80-125 ° C, at which time the pressure in the reactor is ≤ 0.23 MPa. In this stage, part of the hydrolysis product is dehydrated and decarboxylated, while part of the monomer undergoes polymerization reaction;

[0096] The third stage is the aromatization reaction, maintaining the reaction temperature at 160-200°C and the pressure in the reactor at 0.62-1.6 MPa. The polymer produces aromatic cluster compounds, but when their concentration reaches saturation, crystal nuclei are generated. Under the synergistic effect of diffusion and adsorption, the crystal nuclei gradually grow, and as the reaction proceeds, humic acid with a rich surface rich in active oxygen groups is formed (the main product is fulvic acid, accompanied by small amounts of palmitic acid, black humic acid, and low-carbon fusel alcohols);

[0097] The fourth stage: heat preservation and pressure holding stage, maintaining the temperature in the reactor at 200 ° C, the pressure at 1.6 MPa, and the heat preservation and pressure holding time at 60 minutes;

[0098] (2) After the hydrothermal reactor 3 is heated to completion, the valve on the pipeline from the hydrothermal reactor 3 to the flash tank 5 is opened, and the material is discharged into the flash tank 5 at a relatively uniform rate. At the moment the material slurry enters the flash tank 5, the low-boiling-point organic matter (methanol, ethanol, acetic acid, etc.) and part of the water are rapidly vaporized into steam. The steam is pumped to the preheating plate heat exchanger 16 by the vacuum pump 22 in the concentration evaporation unit, and heat is exchanged with the low-concentration fulvic acid delivered by the fulvic acid feed pump 15 in the concentration evaporation unit. The material at the bottom of the flash tank 5 enters the centrifuge 6 for solid-liquid separation, and the solid enters the steam dryer 7 and is dried by the steam of the secondary heating plate heat exchanger 17 in the concentration evaporation unit. The dried solid enters the granulator 8 for granulation, maintaining a certain particle size.

[0099] (3) The liquid from the centrifuge 6 enters the static stratification tank 9 and is left to stand for 4 hours. The upper layer of grease enters the subsequent grease storage tank 10. When the liquid level in the grease storage tank 10 reaches three-quarters, the grease in the grease storage tank 10 is transported to the oil-water separator 12 through the grease delivery pump 11 for oil-water separation. Most of the water is removed from the grease 12 (the water content of the grease is ≤1%), and then enters the biodiesel dehydrator 13 to further reduce the water content of the biodiesel (≤0.05%).

[0100] (4) The liquid at the bottom of the static stratification tank 9 enters the low-concentration fulvic acid storage tank 14 for temporary storage after static separation. When the liquid in the low-concentration fulvic acid storage tank 14 can keep the concentration evaporation unit running for more than 10 hours, the concentration evaporation unit is turned on. The fulvic acid feed pump 15 transports the low-concentration fulvic acid in the low-concentration fulvic acid storage tank 14 to the preheating plate heat exchanger 16 for heat exchange with the steam from the front-end flash tank 5. At this time, the steam from the flash tank 5 is sucked by the vacuum pump 22 and mixed with the new steam generated by the steam generator 23 to enter the secondary heating plate heat exchanger 17. When the steam from the flash tank 5 enters the vacuum buffer tank 21, the condensed water enters the condensed water storage tank 28 through the pipe at the bottom of the vacuum buffer tank 21 (the outlet end of the pipe is always kept under liquid to form a liquid seal). The low-concentration fulvic acid enters the secondary heating plate heat exchanger 17 for a second heating. The temperature increase is controlled. The steam from the secondary heating plate heat exchanger 17 enters the front-end steam dryer 7 for secondary utilization.

[0101] (5) The low-concentration fulvic acid after two heat exchanges enters the inlet of the forced circulation pump 18, and the outlet of the Y-shaped boiling chamber in the evaporator 20 is connected to the inlet of the forced circulation pump 18. The forced circulation pump 18 transports the liquid in the boiling chamber to the shell and tube heat exchanger 19, and the steam generated in the evaporation 20 is sucked by the steam compressor 25 and transported to the shell and tube heat exchanger 19, and heat is exchanged with the low-concentration fulvic acid transported by the forced circulation pump 18 in the shell and tube heat exchanger 19. At this time, the steam condenses in the shell and tube heat exchanger 19, and the condensate is heat-exchanged through the condensate plate heat exchanger 30 and enters the condensate storage tank 28. The drainage pump 29 transports the condensate to the slurry mixing barrel 1 as a heat source or slurry mixing water for the slurry mixing barrel 1;

[0102] (6) The concentration and evaporation unit continuously feeds and evaporates. When the fulvic acid concentration at the bottom of the evaporator 20 exceeds 40%, the discharge pump 26 is turned on to transport the liquid at the bottom of the evaporator to the high-concentration liquid fulvic acid storage tank 27 for cooling, thereby maintaining a balance between the discharge and the feed. When the fulvic acid concentration at the bottom of the evaporator is lower than 40%, the discharge pump 26 is turned off and evaporation and concentration are continued.

[0103] (7) A branch of the steam generator 23 is connected to the steam pipeline from the steam compressor 25 to the shell-and-tube heat exchanger 19. When the condensing and evaporating unit is first started and heated, the steam generated by the steam generator 23 is used to heat the condensing and evaporating unit. When the evaporation chamber produces sufficient steam, this branch can be closed or the steam supply can be reduced. The inlet and outlet pipes of the steam compressor 25 are connected to a bypass branch for quickly starting the centrifugal steam compressor. If a Roots steam compressor is selected, this bypass branch is not included.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0105] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for preparing fulvic acid by hydrothermal reaction of wet garbage, characterized in that: include: hydrothermal reaction unit, solid fulvic acid production unit, biodiesel separation unit and concentration evaporation unit; The hydrothermal reaction unit includes: a slurry mixing barrel, a slurry mixing pump, a hydrothermal reactor, a thermal oil heating device and a flash tank; The slurry preparation barrel, slurry preparation pump, hydrothermal reactor and flash tank are connected in sequence; The thermal oil heating device is cyclically connected to the hydrothermal reactor; The solid fulvic acid production unit includes: a centrifuge, a steam dryer, and a granulator; The flash tank is connected to the centrifuge, steam dryer and granulator in sequence; The biodiesel separation unit includes: a static stratification tank, a grease storage tank, a grease feed pump, an oil-water separator and a biodiesel dehydrator; The centrifuge is connected to the static stratification tank, the grease storage tank, the grease feed pump, the oil-water separator, and the biodiesel dehydrator in sequence; The concentration and evaporation unit includes: a low-concentration fulvic acid storage tank, a fulvic acid feed pump, a preheating plate heat exchanger, a secondary heating plate heat exchanger, a forced circulation pump, a shell and tube heat exchanger, an evaporator, a vacuum buffer tank, a vacuum pump, a steam generator, a secondary demister, a steam compressor, a discharge pump, a high-concentration liquid fulvic acid storage tank, a condensate storage tank, a drainage pump, and a condensate plate heat exchanger; The static stratification tank is connected to the low-concentration fulvic acid storage tank, the fulvic acid feed pump, the preheating plate heat exchanger, the secondary heating plate heat exchanger, the forced circulation pump, the shell and tube heat exchanger, and the evaporator in sequence; One end of the preheating plate heat exchanger is also connected to the flash tank, and the other end is connected to the vacuum buffer tank, the vacuum pump, the secondary heating plate heat exchanger, and the steam dryer in sequence; One end of the steam generator is connected to the pipeline between the vacuum pump and the secondary temperature-raising plate heat exchanger, and the other end is connected to the shell and tube heat exchanger; The secondary defoamer is cyclically connected to the evaporator; One end of the steam compressor is connected to the secondary demister, and the other end is connected to the pipeline between the steam generator and the shell and tube heat exchanger; The evaporator is also connected to the discharge pump and the high-concentration liquid fulvic acid storage tank in sequence; The shell and tube heat exchanger is also connected to the condensate plate heat exchanger, the condensate storage tank, the drainage pump, and the slurry mixing barrel in sequence; The condensed water storage tank is also connected to the vacuum buffer tank.

2. The device for preparing fulvic acid by hydrothermal reaction of wet garbage according to claim 1, characterized in that: The hydrothermal reactor is provided with a pressure relief port and a discharge port, and the pressure relief port and the discharge port are respectively connected to the flash tank; An electric valve, an electric regulating valve and an electric valve are sequentially arranged between the pressure relief port and the flash tank, and between the discharge port and the flash tank.

3. The device for preparing fulvic acid by hydrothermal reaction of wet garbage according to claim 2, characterized in that: The hydrothermal reactor is also provided with a heat transfer oil inlet and a heat transfer oil outlet; the heat transfer oil inlet and the heat transfer oil outlet are both connected to the heat transfer oil heating device; Electric regulating valves are provided between the thermal oil heating device and the thermal oil inlet and between the thermal oil heating device and the thermal oil outlet; A bypass is provided between the two electric regulating valves and the thermal oil heating device, and an electric regulating valve is provided on the bypass.

4. The device for preparing fulvic acid by hydrothermal reaction of wet garbage according to claim 3, characterized in that: An electric regulating valve is provided between the inlet pipeline and the outlet pipeline of the steam compressor; the upper part of the evaporator is an evaporation chamber, and the lower part is a Y-shaped boiling chamber.

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