A method for improving solid-phase conversion rate in biomass hydrothermal treatment

Abstract

This invention provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes performing hydrothermal treatment under the following conditions: the dissolved oxygen content of biomass in water is 10–100 μg / L, the concentration of insoluble organic matter is 2–20 g / L, and the concentration of soluble organic matter is 0.5–8 g / L, with a liquid-to-solid ratio of (2.5–8):1. The method of this invention is simple to operate, easy to control, effectively improves the solid-phase conversion rate in biomass hydrothermal treatment, and has low energy consumption for biomass fuel production, making it suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of biomass energy utilization technology, and in particular to a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. Background Technology

[0002] Biomass includes plants, microorganisms, and animals that feed on plants and microorganisms, as well as their waste products. It is characterized by its large volume, low density, and high storage and transportation costs.

[0003] Currently, hydrothermal treatment technology can be used to convert biomass waste into high-calorific-value, low-salt high-quality fuel.

[0004] CN103386411A discloses a hydrothermal treatment method and system for biomass waste. The method includes: the material sequentially undergoing pulping preheating treatment, high-pressure steam hydrothermal treatment, and flash evaporation treatment. The steam used in the hydrothermal treatment includes raw steam and secondary steam. The secondary steam utilizes the steam pressure difference between the two hydrothermal reactors to achieve pressure and temperature equalization of the steam in both reactors. Through multi-stage pressure equalization between the hydrothermal reactors, heat exchange efficiency is improved, and raw steam consumption is reduced.

[0005] CN101805629A discloses a method for producing fuel oil from biomass liquefaction. The method involves thoroughly mixing biomass feedstock with solvent water (or an aqueous solution with a catalyst) to form a slurry. The mass ratio of catalyst to feedstock is 1:10 to 1:50, and the mass ratio of feedstock to water is 1:2 to 1:8. The reaction is carried out in a slurry bed reactor under a reducing atmosphere. The liquefaction reaction temperature is controlled at 300-450℃, the reaction pressure at 5-30 MPa, and the reaction time at 5-40 min. After the reaction, the product is separated to obtain fuel oil, solid residue, water, and gas. This method achieves complete biomass conversion, high oil yield, and the calorific value of the obtained oil is comparable to that of standard oil. It can alleviate dependence on fossil fuels, is beneficial to environmental protection, has low production costs, and has good social and economic benefits.

[0006] CN113265286A discloses a method and system for preparing clean biomass fuel from agricultural and forestry waste. The method includes: anaerobic fermentation of pretreated kitchen waste to obtain a fermentation slurry comprising fermentation residue and mixed organic acids; acid washing of the pretreated agricultural and forestry biomass to remove alkali metals; hydrothermal treatment of the mixed slurry obtained by mixing the fermentation residue, the acid solution after reaction with the agricultural and forestry biomass, and the acid-washed agricultural and forestry biomass to obtain biomass char; and solid-liquid separation and extrusion molding of the biomass char to obtain clean biomass fuel. The provided method utilizes the mixed organic acids generated from the fermentation of kitchen waste to gently remove alkali metals from agricultural and forestry biomass, and combines the alkali metal-removed agricultural and forestry biomass with the fermentation residue of kitchen waste to prepare biomass fuel, which has advantages such as high efficiency, safety, and economy.

[0007] However, the aforementioned hydrothermal treatment methods and systems do not provide a solution for improving the solid-phase conversion rate in hydrothermal treatment, thereby improving the quality and energy conversion rate of biomass fuel. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. By strictly controlling various conditions and parameters of the hydrothermal reaction, the solid-phase conversion rate can be significantly improved, thereby enhancing the quality of biomass fuel. The method is simple to operate, easy to control, and has low energy consumption, making it suitable for widespread application in biomass fuel preparation.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for improving the solid-phase conversion rate in hydrothermal treatment of biomass, characterized in that the method comprises: hydrothermal treatment under the conditions that the dissolved oxygen content of biomass in water is 10-100 μg / L, the concentration of insoluble organic matter is 2-20 g / L and the concentration of soluble organic matter is 0.5-8 g / L, and the liquid-solid ratio is (2.5-8):1.

[0011] The method for improving the solid-phase conversion rate in biomass hydrothermal treatment described in this invention can effectively improve the solid-phase conversion rate of the hydrothermal treatment products and reduce the liquid-phase conversion rate by controlling the dissolved oxygen content, insoluble organic matter concentration, and soluble organic matter concentration in the water during biomass hydrothermal treatment. Its main reaction mechanism is that high oxygen concentration accelerates the hydrothermal reaction, and high organic matter concentration can hinder the occurrence of hydrothermal liquefaction and gasification, thereby improving the quality and energy conversion rate of biomass fuel, reducing production costs, and obtaining biomass fuel with a higher lower heating value.

[0012] The dissolved oxygen content in the water of this invention is 10 to 100 μg / L, for example, it can be 10 μg / L, 30 μg / L, 50 μg / L, 80 μg / L, 90 μg / L or 100 μg / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] The concentration of insoluble organic matter in water is 2 to 20 g / L, for example, it can be 2 g / L, 4 g / L, 5 g / L, 10 g / L, 13 g / L or 20 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] The concentration of soluble organic matter in water is 0.5 to 8 g / L, for example, it can be 0.5 g / L, 1 g / L, 3 g / L, 5 g / L, 7 g / L or 8 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] The liquid-to-solid ratio is (2.5 to 8):1, for example, it can be 2.5:1, 3:1, 4:1, 5:1, 6:1 or 8:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the biomass includes corn stalks.

[0017] Preferably, the water content of the biomass is 0 to 70 wt%, for example, it can be 0 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or 70 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the material is crushed before the hydrothermal treatment.

[0019] Preferably, the pressure of the hydrothermal treatment is 0.5 to 3.9 MPaG, for example, it can be 0.5 MPaG, 0.8 MPaG, 1 MPaG, 1.5 MPaG, 2 MPaG or 3.9 MPaG, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the temperature of the hydrothermal treatment is 159 to 250°C, for example, it can be 159°C, 180°C, 200°C, 220°C, 240°C or 250°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the liquid-to-solid ratio of the hydrothermal treatment is (3-5):1, for example, it can be 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, during the hydrothermal treatment, the dissolved oxygen content in the water is 10–50 μg / L, for example, it can be 10 μg / L, 20 μg / L, 30 μg / L, 40 μg / L, 45 μg / L or 50 μg / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, during the hydrothermal treatment, the concentration of insoluble organic matter in the water is 5 to 15 g / L, for example, it can be 5 g / L, 8 g / L, 10 g / L, 12 g / L, 13 g / L or 15 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, during the hydrothermal treatment, the concentration of soluble organic matter in the water is 1 to 5 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 3.5 g / L, 4 g / L or 5 g / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] The method for improving the solid-phase conversion rate in biomass hydrothermal treatment provided by this invention is simple to operate. By controlling various conditions and parameters during the hydrothermal reaction, the quality of biomass fuel is improved, and the energy conversion rate can reach over 90%. The biomass fuel preparation cost is low, making it suitable for large-scale promotion and application. Detailed Implementation

[0027] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0028] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0029] The biomass used in the following examples and comparative examples is corn straw, which has a dry basis lower heating value of 15.44 MJ / Kg and a moisture content of 31.3%.

[0030] Example 1

[0031] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out under the following conditions: the dissolved oxygen content in water is 45 μg / L, the concentration of insoluble organic matter is 6.7 g / L, and the concentration of soluble organic matter is 2.8 g / L, and the liquid-to-solid ratio is 5:1, the pressure is 1.0 MPaG, and the temperature is 190°C.

[0032] Example 2

[0033] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out under the following conditions: the dissolved oxygen content in water is 10 μg / L, the concentration of insoluble organic matter is 10.1 g / L, and the concentration of soluble organic matter is 4.2 g / L, and the liquid-to-solid ratio is 5:1, the pressure is 1.0 MPaG, and the temperature is 190°C.

[0034] Example 3

[0035] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out in water with a dissolved oxygen content of 100 μg / L, an insoluble organic matter concentration of 2 g / L, and a soluble organic matter concentration of 0.5 g / L, and a liquid-to-solid ratio of 2.5:1, a pressure of 0.5 MPaG, and a temperature of 159°C.

[0036] Example 4

[0037] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out in water with a dissolved oxygen content of 80 μg / L, an insoluble organic matter concentration of 20 g / L, a soluble organic matter concentration of 8 g / L, a liquid-to-solid ratio of 8:1, a pressure of 3.9 MPaG, and a temperature of 250°C.

[0038] Comparative Example 1

[0039] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out in water with a dissolved oxygen content of 400 μg / L, an insoluble organic matter concentration of 50 g / L, a soluble organic matter concentration of 20 g / L, a liquid-to-solid ratio of 8:1, a pressure of 3.9 MPaG, and a temperature of 250°C.

[0040] Comparative Example 2

[0041] This embodiment provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method includes: after the biomass is crushed, hydrothermal treatment is carried out in water with a dissolved oxygen content of 200 μg / L, an insoluble organic matter concentration of 0.2 g / L, a soluble organic matter concentration of 0.1 g / L, a liquid-to-solid ratio of 5:1, a pressure of 0.5 MPaG, and a temperature of 159°C.

[0042] Comparative Example 3

[0043] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the dissolved oxygen content in the water is replaced with 8 μg / L instead of 45 μg / L.

[0044] Comparative Example 4

[0045] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the dissolved oxygen content in the water is replaced by 105 μg / L instead of 45 μg / L.

[0046] Comparative Example 5

[0047] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the concentration of insoluble organic matter in water is replaced by 1 μg / L instead of 6.7 μg / L.

[0048] Comparative Example 6

[0049] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the concentration of insoluble organic matter in the water is replaced by 24 μg / L instead of 6.7 μg / L.

[0050] Comparative Example 7

[0051] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the concentration of soluble organic matter in water is replaced from 2.8 μg / L to 0.1 μg / L.

[0052] Comparative Example 8

[0053] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the concentration of soluble organic matter in water is replaced from 2.8 μg / L to 10 μg / L.

[0054] Comparative Example 9

[0055] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the liquid-solid ratio is replaced with 2.5:1 instead of 5:1.

[0056] Comparative Example 10

[0057] This comparative example provides a method for improving the solid-phase conversion rate in biomass hydrothermal treatment. The method is the same as in Example 1, except that the liquid-solid ratio is replaced with 8:1 instead of 5:1.

[0058] The dry basis product yield, lower heating value and energy yield of the biomass fuel obtained by dehydration and drying of the hydrothermal products obtained after hydrothermal treatment in the above embodiments and comparative examples are shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] As can be seen from Table 1:

[0063] (1) As can be seen from the comprehensive examples 1 to 4, by using the method provided by the present invention to improve the solid-phase conversion rate in the hydrothermal treatment of biomass, the final yield of the dry-based product of biomass fuel can reach 77.4%, and the energy yield can reach 90.4%, which significantly reduces the cost of biomass fuel preparation. Moreover, under high temperature and high pressure parameters, the lower heating value of the dry-based product of the obtained biomass fuel can reach 21.5 MJ / kg.

[0064] (2) It can be seen from the comprehensive examples 1 and 10 to 10 that when hydrothermal treatment is performed, the content of dissolved oxygen in water, the concentration of insoluble organic matter in water, the concentration of soluble organic matter in water and the liquid-solid ratio are not within the range specified in this application. The solid-phase conversion rate is low during hydrothermal treatment, and the dry-based product yield of the final biomass fuel is low.

[0065] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for improving the conversion of solid phase in the hydrothermal treatment of biomass, characterized in that, The method includes: hydrothermal treatment of biomass in water with dissolved oxygen content of 10-50 μg / L, insoluble organic matter concentration of 5-15 g / L and soluble organic matter concentration of 1-5 g / L, and liquid-solid ratio of (3-5):1; wherein the biomass is corn straw.

2. The method of claim 1, wherein, The biomass has a moisture content of 0 to 70 wt%.

3. The method of claim 1, wherein, The material is crushed before undergoing hydrothermal treatment.

4. The method of claim 1, wherein, The pressure of the hydrothermal treatment is 0.5~3.9 MPaG.

5. The method according to claim 1, characterized in that, The temperature of the hydrothermal treatment is 159~250℃.

Images