A system and method for preparing organic fertilizer by coupling thermal hydrolysis of biogas residue

Abstract

The present application relates to a kind of hot hydrolysis biogas residue coupling preparation organic fertilizer system and method, comprising the following steps: livestock manure enters anaerobic fermentation system, and anaerobic fermentation is carried out;Part of biogas slurry with biogas residue is separated by first solid-liquid separator to obtain separated biogas slurry and biogas residue, and another part of biogas slurry with biogas residue sequentially passes through heat hydrolysis system and heat exchange cooling device;The fermentation mixture of one-stage aerobic fermentation device outlet and the biogas residue of second solid-liquid separator outlet are mixed, enter aging device, and finally form organic fertilizer.The beneficial effects of the present application are: through heat hydrolysis process, the separated biogas slurry can be reused, the amount of biogas residue is reduced and the system processing capacity of aerobic fermentation preparation organic fertilizer is reduced;Harmful bacteria in biogas residue are killed by high temperature formed in heat hydrolysis process;Macromolecular organic matter is cracked into small molecular organic matter by heat hydrolysis, and the viscosity of biogas slurry is greatly reduced, so that the moisture content of biogas residue after solid-liquid separation is reduced.

Description

Technical Field

[0001] This invention belongs to the field of biogas engineering and biogas slurry treatment technology, and particularly relates to a system and method for preparing organic fertilizer by coupling hot water hydrolysis of biogas residue. Background Technology

[0002] The biogas slurry produced after anaerobic fermentation contains a large amount of macromolecular organic matter, making it highly viscous. The biogas residue obtained after solid-liquid separation not only contains a large number of microorganisms but also has a high moisture content. It is necessary to add auxiliary materials to reduce the moisture content and increase the organic matter content, and then further reduce the moisture through aerobic fermentation sterilization to produce qualified organic fertilizer. The above-mentioned organic fertilizer preparation process requires the addition of a large amount of auxiliary materials and an additional sterilization step, resulting in high energy consumption and increased production costs.

[0003] Based on the above problems, there is an urgent need for a new system and method for preparing organic fertilizer to simplify the process, reduce energy consumption, and reduce the amount of auxiliary materials used. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for preparing organic fertilizer by coupling hot water hydrolysis residue.

[0005] This hot water hydrolysis residue coupled organic fertilizer preparation system includes an anaerobic fermentation system, a first solid-liquid separator, a first-stage aerobic fermentation device, a hot water hydrolysis system, a heat exchange and cooling device, a second solid-liquid separator, and an aging device.

[0006] One outlet of the anaerobic fermentation system is connected to the first solid-liquid separator, and the outlet of the first solid-liquid separator is connected in sequence to an aerobic fermentation device and an aging device.

[0007] Another outlet of the anaerobic fermentation system is connected to the hot hydrolysis system. The outlet of the hot hydrolysis system is connected in sequence to the heat exchange and cooling device and the second solid-liquid separator. The outlet of the second solid-liquid separator is divided into two paths: one path is connected to the inlet of the anaerobic fermentation system, and the other path merges with the outlet section of an aerobic fermentation device.

[0008] As a preferred embodiment, it also includes a two-stage aerobic fermentation device, which is located between the first-stage aerobic fermentation device and the aging device; one outlet of the second solid-liquid separator and the outlet section of the first-stage aerobic fermentation device are connected to the inlet of the two-stage aerobic fermentation device, and the outlet of the two-stage aerobic fermentation device is connected to the inlet of the aging device.

[0009] As a preferred option, the second solid-liquid separator is a plate filter press.

[0010] As a preferred option, the aerobic fermentation device is equipped with an aeration fan and a turning machine.

[0011] This method for preparing organic fertilizer using a hot water hydrolysis residue coupled system includes the following steps:

[0012] Step 1: Livestock and poultry manure enters the anaerobic fermentation system for anaerobic fermentation, yielding biogas slurry containing biogas residue;

[0013] Step 2: A portion of the biogas slurry containing biogas residue passes through the first solid-liquid separator to obtain separated biogas slurry and biogas residue. The biogas residue enters a first-stage aerobic fermentation device and is mixed with auxiliary materials for a first-stage aerobic fermentation to obtain a fermentation mixture. The biogas slurry enters the biogas slurry treatment system for processing.

[0014] Another portion of the biogas slurry containing biogas residue is passed through a hot hydrolysis system and a heat exchange and cooling device in sequence, and then through a second solid-liquid separator to separate the biogas slurry and biogas residue. The biogas slurry is reused in the anaerobic fermentation system to re-ferment and produce biogas.

[0015] Step 3: The fermentation mixture from the outlet of the first aerobic fermentation unit and the biogas residue from the outlet of the second solid-liquid separator are mixed and enter the aging unit to finally form organic fertilizer.

[0016] As a preferred option, in step two, the maximum fermentation temperature during the first stage of aerobic fermentation is higher than 70℃.

[0017] Preferably, in step two, the temperature of the biogas slurry containing biogas residue after hot hydrolysis is below 60°C after being treated by a heat exchange and cooling device.

[0018] As a preferred option, a two-stage aerobic fermentation device is also provided; the fermentation mixture from the outlet of the first-stage aerobic fermentation device is mixed with the biogas residue from the outlet of the second solid-liquid separator and then enters the second-stage aerobic fermentation device for second-stage aerobic fermentation, and then enters the aging device.

[0019] The beneficial effects of this invention are:

[0020] 1) The biogas slurry after solid-liquid separation can be reused and anaerobic fermented to produce biogas, which improves the efficiency of solid recovery. It not only reduces the amount of biogas slurry but also the amount of biogas residue and reduces the system processing capacity for aerobic fermentation to produce organic fertilizer, thus saving costs.

[0021] 2) The high temperature of the hot hydrolysis system kills harmful bacteria in the biogas residue; hot hydrolysis breaks down large organic molecules into small organic molecules, significantly reducing the viscosity of the biogas slurry, thus reducing the water content of the biogas residue after solid-liquid separation, reducing the amount of auxiliary materials used, thereby reducing investment and operating costs.

[0022] 3) A plate filter press can be used as a second solid-liquid separator to reduce the water content of the biogas residue. The biogas residue can be directly mixed with the fermentation mixture of the first stage of aerobic fermentation and then aged and decomposed. It only needs to pass through the first stage of aerobic fermentation device before entering the aging device to prepare organic fertilizer. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process flow of this patent.

[0024] Explanation of reference numerals in the attached diagram: 1. Anaerobic fermentation system; 2. First solid-liquid separator; 3. First-stage aerobic fermentation device; 4. Hot water hydrolysis system; 5. Heat exchange and cooling device; 6. Second solid-liquid separator; 7. Second-stage aerobic fermentation device; 8. Aging device. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0026] Example 1

[0027] As one embodiment, this embodiment proposes a hot water hydrolysis residue coupled organic fertilizer preparation system, including: anaerobic fermentation system 1, first solid-liquid separator 2, first aerobic fermentation device 3, hot water hydrolysis system 4, heat exchange and cooling device 5, second solid-liquid separator 6, and aging device 8;

[0028] One outlet of the anaerobic fermentation system 1 is connected to the first solid-liquid separator 2. The outlet of the first solid-liquid separator 2 is connected in sequence to the first aerobic fermentation device 3 and the aging device 8. The first aerobic fermentation device 3 is equipped with an aeration fan and a turning machine. The first aerobic fermentation device 3 is also equipped with auxiliary materials to increase the organic matter content and reduce the moisture content, which helps the filter residue to fully ferment and reduce the moisture content of the filter residue.

[0029] Another outlet of the anaerobic fermentation system 1 is connected to the hot water hydrolysis system 4. The outlet of the hot water hydrolysis system 4 is connected in sequence to the heat exchange and cooling device 5 and the second solid-liquid separator 6. The outlet of the second solid-liquid separator 6 is divided into two paths: one path is connected to the inlet of the anaerobic fermentation system 1, and the other path merges with the outlet section of the aerobic fermentation device 3.

[0030] The second solid-liquid separator 6 is a plate filter press. Under high pressure, it can directly reduce the moisture content of biogas residue to below 45%. After crushing, it can be directly used in the aging and composting process of the aging device 8.

[0031] Example 2

[0032] As another embodiment, this embodiment adds a two-stage aerobic fermentation device 7 to the first embodiment, such as... Figure 1As shown, the two-stage aerobic fermentation device 7 is located between the first-stage aerobic fermentation device 3 and the aging device 8. At this time, the second solid-liquid separator 6 is a high-speed centrifuge, and the resulting filter residue has a moisture content of 50%, which is higher than the 45% obtained by the plate filter press in Example 1. Therefore, the two-stage aerobic fermentation device 7 is needed to further reduce the moisture content of the fermented material to below 45%.

[0033] The outlet of the second solid-liquid separator 6 and the outlet of the first aerobic fermentation device 3 are connected to the inlet of the second aerobic fermentation device 7, and the outlet of the second aerobic fermentation device 7 is connected to the inlet of the aging device 8.

[0034] Example 3

[0035] The organic fertilizer preparation method according to the hot water decomposition residue coupled organic fertilizer preparation system proposed in Example 1 includes the following steps:

[0036] Step 1: Livestock and poultry manure enters the anaerobic fermentation system 1 for anaerobic fermentation to obtain biogas slurry containing biogas residue;

[0037] Step 2: A portion of the biogas slurry containing biogas residue passes through the first solid-liquid separator 2 to separate the biogas slurry and biogas residue. The biogas residue enters the first-stage aerobic fermentation device 3, while the biogas slurry enters the biogas slurry treatment system for treatment. After treatment to meet standards, it is discharged or returned to the field. A certain amount of auxiliary materials need to be added to the first-stage aerobic fermentation device 3 to reduce the moisture content and increase the organic matter content. Through the ventilation of a high-power aeration blower and the oxygenation of the turning machine, a relatively long-term first-stage aerobic fermentation is carried out, and the fermentation temperature rises to a maximum of over 70°C, killing harmful microorganisms and reducing the moisture content of the fermentation mixture from 70% to about 50%.

[0038] Another portion of the biogas slurry containing biogas residue passes through the hot hydrolysis system 4. Under the high temperature and pressure of steam, the remaining large-molecule organic matter in the biogas slurry is broken down into small-molecule organic matter, reducing the viscosity of the biogas slurry. After flash evaporation, it enters the heat exchange and cooling device 5 to be cooled to below 60°C. At this point, the viscosity of the biogas slurry has been significantly reduced, which also reduces the difficulty of solid-liquid separation between the biogas slurry and biogas residue. Then, it passes through the second solid-liquid separator 6 for solid-liquid separation. The second solid-liquid separator 6 can be a plate and frame filter press to obtain the separated biogas slurry and biogas residue. Under the function of high pressure pressing, the water content of the biogas residue is less than 45%. The biogas slurry is reused in the anaerobic fermentation system 1 to re-ferment and produce more biogas, and no further biogas slurry treatment is required.

[0039] Step 3: The fermentation mixture from the outlet of the first aerobic fermentation device 3 and the biogas residue from the outlet of the second solid-liquid separator 6 are crushed and mixed, and then enter the aging device 8 to finally form organic fertilizer.

[0040] In this method of preparing organic fertilizer, the biogas residue after hot hydrolysis and solid-liquid separation is no longer repeatedly fed into the first-stage aerobic fermentation device 3 for aerobic fermentation, which reduces the amount of auxiliary materials, as well as the volume and aeration of the first-stage aerobic fermentation device 3, thereby reducing investment and operating costs.

[0041] Example 4

[0042] Based on the hot water decomposition residue coupled organic fertilizer preparation system proposed in Example 2, this example proposes an organic fertilizer preparation method using the hot water decomposition residue coupled organic fertilizer preparation system.

[0043] The organic fertilizer preparation method of this hot water hydrolysis residue coupled organic fertilizer preparation system is similar to that in Example 3, except that the second solid-liquid separator 6 is replaced by a high-speed centrifuge, resulting in a biogas residue moisture content of 50% to 60%, which is higher than the filter residue in Example 3. Before aging and composting, the fermentation mixture from the outlet of the first-stage aerobic fermentation device 3 and the biogas residue from the outlet of the second solid-liquid separator 6 need to be mixed and then fed into the second-stage aerobic fermentation device 7 for second-stage aerobic fermentation.

[0044] At this point, the two-stage aerobic fermentation device 7 uses a low-power aeration fan for ventilation, with a smaller residence time and aeration volume, and no auxiliary materials are added; the moisture content of the fermentation mixture is further reduced to below 45% through the two-stage aerobic fermentation, and then the final aging and maturation are carried out in the aging device 8.

Claims

1. A system for coupling the preparation of organic fertilizer from biogas residue using hot water, characterized in that, include: Anaerobic fermentation system (1), first solid-liquid separator (2), first-stage aerobic fermentation device (3), hot water hydrolysis system (4), heat exchange and cooling device (5), second solid-liquid separator (6) and aging device (8); One outlet of the anaerobic fermentation system (1) is connected to the first solid-liquid separator (2), and the outlet of the first solid-liquid separator (2) is connected in sequence to an aerobic fermentation device (3) and an aging device (8). Another outlet of the anaerobic fermentation system (1) is connected to the hot water hydrolysis system (4). The outlet of the hot water hydrolysis system (4) is connected in sequence to the heat exchange and cooling device (5) and the second solid-liquid separator (6). The outlet of the second solid-liquid separator (6) is divided into two paths, one of which is connected to the inlet of the anaerobic fermentation system (1), and the other path merges with the outlet section of the aerobic fermentation device (3). It also includes a two-stage aerobic fermentation device (7), which is located between the first-stage aerobic fermentation device (3) and the aging device (8); one outlet of the second solid-liquid separator (6) and the outlet of the first-stage aerobic fermentation device (3) are connected to the inlet of the two-stage aerobic fermentation device (7), and the outlet of the two-stage aerobic fermentation device (7) is connected to the inlet of the aging device (8); An aerobic fermentation device (3) is equipped with an aeration fan and a turning machine.

2. The system for preparing organic fertilizer by coupling hot water hydrolysis residue according to claim 1, characterized in that: The second solid-liquid separator (6) is a plate filter press.

3. The method for preparing organic fertilizer using the hot water hydrolysis residue coupled organic fertilizer preparation system as described in claim 1, characterized in that, Includes the following steps: Step 1: Livestock and poultry manure enters the anaerobic fermentation system (1) for anaerobic fermentation to obtain biogas slurry containing biogas residue; Step 2: A portion of the biogas slurry containing biogas residue passes through the first solid-liquid separator (2) to obtain separated biogas slurry and biogas residue. The biogas residue enters a first-stage aerobic fermentation device (3) and is mixed with auxiliary materials to undergo a first-stage aerobic fermentation to obtain a fermentation mixture. The biogas slurry enters the biogas slurry treatment system for treatment. Another part of the biogas slurry containing biogas residue passes through the hot hydrolysis system (4) and the heat exchange and cooling device (5) in sequence, and then passes through the second solid-liquid separator (6) for solid-liquid separation to obtain the separated biogas slurry and biogas residue. The biogas slurry is reused in the anaerobic fermentation system (1) to re-ferment and produce biogas. Step 3: The fermentation mixture from the outlet of the first-stage aerobic fermentation device (3) and the biogas residue from the outlet of the second solid-liquid separator (6) are mixed and enter the aging device (8) to finally form organic fertilizer; there is also a second-stage aerobic fermentation device (7); the fermentation mixture from the outlet of the first-stage aerobic fermentation device (3) and the biogas residue from the outlet of the second solid-liquid separator (6) are mixed and enter the second-stage aerobic fermentation device (7) for second-stage aerobic fermentation, and then enter the aging device (8).

4. The method for preparing organic fertilizer using the hot water hydrolysis residue coupled organic fertilizer preparation system according to claim 3, characterized in that, In step two: the maximum fermentation temperature during the first stage of aerobic fermentation exceeds 70℃.

5. The method for preparing organic fertilizer using the hot water hydrolysis residue coupled organic fertilizer preparation system according to claim 3, characterized in that, In step two: the temperature of the biogas slurry containing biogas residue after hot hydrolysis is lower than 60℃ after being treated by the heat exchange and cooling device (5).

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