Biomass heavy oil composite synergistic biomass briquette fuel and preparation method thereof

Abstract

The invention discloses a biomass briquette fuel for composite synergism of biomass heavy oil and a preparation method of the biomass briquette fuel. The preparation method of the biomass briquette fuel for composite synergism of the biomass heavy oil comprises the following steps: a) pretreatment: dissolving the biomass heavy oil into an organic solvent to obtain a biomass heavy oil solute, and crushing the biomass to form a crushed biomass material; b) drying and pre-wetting: mixing the biomass heavy oil solute with the biomass crushed material, drying to remove the organic solvent, adding water, and stirring to obtain the biomass crushed material; c) pressing and forming: pressing the crushed biomass into a finished fuel product; according to the invention, the biomass heavy oil is used as the binder for biomass cold press molding, so that the problems of high cost, poor combustion performance and the like of the existing binder can be solved, and the co-processing of the biomass heavy oil and the biomass can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass energy conversion, in particular to the technical field of biomass fuel. Background Art

[0002] Biomass refers to various organisms formed through photosynthesis. It is a zero-carbon renewable energy resource. In my country, it is not only abundant in reserves but also widely distributed. However, the low density, high oxygen content, low volume energy density and wide distribution of biomass itself lead to high collection and transportation costs, thus limiting its widespread application. To solve this problem, researchers have proposed biomass molding technology (i.e., compressing loose biomass into various shapes, such as granules, rods and blocks, thereby significantly increasing the density and energy of biomass). This solidification molding technology is one of the important directions of biomass energy conversion and utilization due to its low cost, simple process and good economic benefits.

[0003] Biomass pellet fuel is a fuel made from biomass as the main raw material through biomass pelletizing technology. The quality of biomass pellet fuel can be judged by its physical properties and combustion characteristics. In addition, by studying the correlation between influencing factors and the quality of biomass pellet fuel, the preparation method of high-quality biomass pellet fuel can be explored.

[0004] Biomass molded fuel usually has disadvantages such as loose structure, low density and poor durability, so people often add additional binders during cold pressing and carbonization molding. Generally speaking, the selection of binders mainly considers cost, effect and environmental friendliness. According to the composition, binders can be divided into organic binders, inorganic binders and composite binders. Among them, organic binders are usually starch and cellulose, such as a composite biomass fuel with publication number CN112500902A, which uses a binder composed of wood cellulose and gelatinized starch. Although such binders have good bonding properties, they are often expensive (not conducive to large-scale use). Inorganic binders mainly include metal salts and industrial solids. Waste, such as the binder prepared from sewage sludge, biomass hydrolyzate, industrial organic waste liquid and waste residue used in the sludge biomass molding fuel with publication number CN102465048A; although such binders have the advantages of wide sources and low cost, they may cause secondary pollution, increase ash content and reduce combustion performance; in addition, composite binders containing the above-mentioned organic components and inorganic components at the same time, such as the binder composed of furfural residue, clay and gelatinized starch used in a biomass fuel and its preparation method with publication number CN112500900A, may have both of the above-mentioned disadvantages; that is, it is still necessary to strengthen research and develop more binders with excellent performance and low cost to improve biomass molding fuel. Summary of the Invention

[0005] Based on the physicochemical properties of high viscosity and high calorific value of biomass heavy oil, the present invention proposes a biomass molding fuel with composite synergy of biomass heavy oil and a preparation method thereof. Biomass heavy oil can be used as a binder for biomass cold pressing molding, thereby not only solving the problems of high cost and poor combustion performance of existing binders, but also realizing the coordinated disposal of biomass heavy oil and biomass.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions: The preparation method of biomass briquette fuel with biomass heavy oil composite synergistic effect comprises the following steps: a) Pretreatment: dissolving the biomass heavy oil in an organic solvent to obtain a biomass heavy oil dissolved product, and simultaneously crushing the biomass to form a biomass crushed product; b) Drying and pre-wetting: first, the biomass heavy oil solution and the biomass crushed material are mixed and dried to remove the organic solvent, and then water is added and stirred to obtain the biomass crushed material; c) Pressing and molding: Pressing the biomass fragments into finished fuel.

[0007] Preferably, in step a), the amount of the organic solvent added is 5 to 15 times the mass of the biomass heavy oil. Biomass heavy oil is a heavy component oil with binder properties obtained by subjecting oil produced by processes such as cracking or gasification of biomass to specific separation, thermochemical processing, fractionation, and modification. Based on the physical and chemical properties of biomass heavy oil, it can provide a low-cost, readily available, high-yield, non-toxic, easily degradable adhesive with high adhesion and high calorific value for the production process of biomass solid fuel, thereby achieving synergistic conversion and disposal of biomass and biomass heavy oil. However, since biomass heavy oil is typically a dark brown, viscous paste (with poor fluidity), it is difficult to ensure complete and uniform mixing between the two if it is directly mixed with biomass. To this end, the present invention pre-adds a certain amount of organic solvent to the biomass heavy oil, which can be used to dissolve the biomass heavy oil, thereby greatly improving its fluidity, facilitating uniform mixing between the biomass heavy oil and biomass, and ultimately improving the molding quality of biomass briquette fuel.

[0008] Preferably, in step a), the biomass heavy oil is a heavy component of biomass pyrolysis oil and / or a heavy component of biomass gasification tar, the organic solvent is an organic dry and recoverable solvent, and the biomass is one or a combination of crop residues, medicinal and food processing by-products, fruit shell materials, and bamboo and wood processing materials.

[0009] Furthermore, in step a), the heavy component of biomass pyrolysis oil and the heavy component of biomass gasification tar are residual fractions (mainly containing phenols, organic acids and ketones) obtained by molecular distillation of biomass pyrolysis oil and biomass gasification tar under conditions of 150-200 Pa and 55-65° C.; molecular distillation separates compounds by the difference in molecular mean free path; small molecular compounds have a longer mean free path (greater than the distance from the evaporation surface to the condensation surface), so after leaving the evaporation surface, they easily reach the condensation surface and condense, and no longer return, while the mean free path of large molecular compounds is less than the distance from the evaporation surface to the condensation surface, and they are more likely to return to the evaporation surface than small molecules; therefore, the heavy component of bio-oil can be separated by molecular distillation.

[0010] Furthermore, the organic solvent is a dry and recyclable organic solvent selected from one or a combination of ethanol, methanol, acetone and dichloromethane; such solvents can not only be completely removed by evaporation under normal pressure or vacuum drying conditions (temperature > boiling point) (low residual risk), but can also be recycled and reused, significantly reducing production costs and reducing waste liquid emissions.

[0011] Furthermore, the crop residues are one or more combinations of straw, corn cobs and sugarcane bagasse, the medicinal food processing by-products are one or more combinations of bean dregs, fruit residues, wine lees, tea residues, medicinal residues and fungus residues, the fruit shell materials are one or more combinations of walnut shells, pine nut shells, peanut shells, chestnut shells and coconut shells, and the bamboo and wood processing materials are one or more combinations of bamboo, wood, sawdust, bark, branches and leaves.

[0012] Preferably, in step b), the biomass heavy oil dissolved material and the biomass crushed material are mixed in a weight ratio of biomass heavy oil:biomass of 10-20:70-80.

[0013] Preferably, in step b), the drying temperature is 80-100° C. and the drying time is 600-720 min; Preferably, in step b), the amount of water added is 5 to 10% of the total weight of the biomass crushed material; wherein, the purpose of adding water to the unmolded fuel is to increase the contact area between particles, reduce the friction between particles, promote particle flow, and thus reduce the pressure required for subsequent biomass molding.

[0014] Furthermore, in step b), water is added drop by drop; wherein, the drop-by-drop addition method allows trace water droplets to gradually penetrate into the biomass crushed material during the stirring process, ensuring uniform dispersion of water, avoiding adhesion between particles of highly hygroscopic components due to rapid water injection and forming difficult-to-disperse clumps, effectively improving the homogeneity of the mixture, and providing density and structural stability for subsequent finished fuel; in addition, the drop-by-drop addition method can accurately control the water content, thereby facilitating real-time monitoring of the humidity state of the mixture, avoiding the looseness or insufficient strength of the molded fuel caused by excessive water addition, and promoting the activation of the binder, thereby improving the bonding strength and durability of the fuel particles.

[0015] Preferably, in step c), the biomass crushed material is cold pressed under a pressure of 10 to 20 MPa; wherein, adjusting the molding pressure can reduce the distance between particles and promote elastic and plastic deformation of the particles.

[0016] The biomass shaped fuel with composite synergistic effect of biomass and heavy oil is prepared by the above preparation method.

[0017] Beneficial effects of the present invention: 1) This invention innovatively utilizes biomass heavy oil as a binder for biomass briquette fuel, solving the problem of subsequent treatment of pyrolysis heavy oil while reducing the biomass briquette fuel's dependence on traditional binders (and simultaneously eliminating the procurement and pretreatment of traditional binders, significantly reducing overall production costs). This creates a green recycling model of "waste treatment" (i.e., achieving efficient and coordinated utilization of biomass solid and liquid products). Furthermore, this method is compatible with a variety of raw materials, including straw and sawdust, and has the potential for industrial promotion. 2) On the one hand, the present invention can utilize the high viscosity of pyrolysis heavy oil to promote the rapid molding of biomass briquette fuel, enhance the durability of biomass briquette fuel, reduce transportation and storage losses, and overcome the technical bottleneck of traditional cold-pressed briquette fuel that is prone to loosening. On the other hand, it can also directly convert the high calorific value of pyrolysis heavy oil into a fuel energy density advantage, significantly increasing the calorific value of biomass briquette fuel compared to conventional products (reaching or exceeding the level of some low-rank coal), effectively improving the market competitiveness of biomass briquette fuel; 3) The present invention adopts cold pressing technology to press and form biomass crushed materials, which can significantly reduce production energy consumption compared to hot pressing processes. In addition, since a special amount of water is added to the biomass crushed materials, the water can be used to increase the contact area between particles of the unformed fuel, reduce the friction between particles, and promote particle flow, thereby reducing the pressure required for subsequent biomass forming and further reducing process energy consumption.

[0018] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of Example 1; Figure 2 This is a physical picture of the finished fuel obtained by processing in Examples 1 to 3. DETAILED DESCRIPTION

[0020] Example 1: See Figure 1 The preparation method of biomass briquette fuel with biomass heavy oil composite synergistic effect includes the following steps: a) Pretreatment: First, 2.12 g of biomass heavy oil (the undistilled fraction of walnut shell pyrolysis oil after molecular distillation at 60°C and 165 Pa) was poured into a beaker, and then 30 g of organic solvent (ethanol) was added and stirred uniformly using a mechanical stirrer until the biomass heavy oil was fully dissolved in the organic solvent to obtain a biomass heavy oil dissolved material; at the same time, 17 g of biomass (straw) was crushed to form a biomass crushed material; b) Drying and pre-wetting: The biomass heavy oil solution and the biomass crushed material were first mixed using a mechanical stirrer, and then transferred to an oven for drying (drying temperature: 100°C, drying time: 600 min) to remove the organic solvent. Water was then added dropwise (the amount of water added was 10% of the total weight of the biomass crushed material) and stirred using a mechanical stirrer to obtain the biomass crushed material. c) Pressing and forming: The biomass crushed material is cold pressed and formed on an electronic hydraulic tablet press at a pressure of 20 MPa, thereby pressing the biomass crushed material into finished fuel (such as Figure 2 (as shown in part (a) of the ).

[0021] Example 2: The addition amount of biomass heavy oil is 3.18g, and the addition amount of organic solvent is 47.7g; other aspects are the same as in Example 1; in addition, the finished fuel is as follows Figure 2 As shown in part (b) of .

[0022] Example 3: The addition amount of biomass heavy oil is 4.25g, and the addition amount of organic solvent is 63.75g; other aspects are the same as in Example 1; in addition, the finished fuel is as follows Figure 2 As shown in part (c) of .

[0023] Comparative Example 1: This comparative example is a control group of Examples 1 to 3. In this comparative example, bentonite is used as a binder to be mixed with straw, and molding is carried out under the same molding conditions as Examples 1 to 3. The specific steps are as follows: Step 1: First, put 2.1g of bentonite and 17g of straw powder into a beaker and stir them evenly with a mechanical stirrer. Then, add water drop by drop (the amount of water added is also 10wt%) and continue stirring until evenly mixed. Step 2: Cold pressing is performed on an electronic hydraulic tablet press at a pressure of 20 MPa to obtain the final control fuel product.

[0024] In addition, the density, drop strength and calorific value of the finished fuels prepared in Examples 1 to 3 and the control fuel prepared in Comparative Example 1 were tested respectively.

[0025]

[0026] Table 1 Comparison of fuel properties of Examples 1 to 3 and Comparative Example 1

[0027] The results are shown in Table 1 above. Compared with the traditional biomass molded fuel obtained by using bentonite as a binder, the biomass heavy oil composite enhanced biomass molded fuel proposed in the present invention has a higher calorific value, and the density and drop strength meet the various indicators in the DB 12 / T 663-2016 standard, which is convenient for subsequent storage and can realize the synergistic conversion of biomass heavy oil and biomass.

[0028] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. A method for preparing biomass briquette fuel with composite synergistic effect of biomass and heavy oil, characterized in that: The steps include: a) Pretreatment: dissolving the biomass heavy oil in an organic solvent to obtain a biomass heavy oil dissolved product, and simultaneously crushing the biomass to form a biomass crushed product; b) Drying and pre-wetting: first, the biomass heavy oil solution and the biomass crushed material are mixed and dried to remove the organic solvent, and then water is added and stirred to obtain the biomass crushed material; c) Pressing and molding: Pressing the biomass fragments into finished fuel.

2. The method for preparing the biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step a), the amount of the organic solvent added is 5 to 15 times the mass of the biomass heavy oil.

3. The method for preparing the biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step a), the biomass heavy oil is a heavy component of biomass pyrolysis oil and / or a heavy component of biomass gasification tar, the organic solvent is an organic dry and recyclable solvent, and the biomass is one or a combination of crop residues, medicinal and food processing by-products, fruit shell materials, and bamboo and wood processing materials.

4. The method for preparing the biomass-heavy oil composite synergistic biomass briquette fuel according to claim 3, characterized in that: In step a), the heavy components of biomass pyrolysis oil and biomass gasification tar are residual fractions obtained by molecular distillation of biomass pyrolysis oil and biomass gasification tar at 150-200 Pa and 55-65° C., respectively.

5. The method for preparing biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step b), the biomass heavy oil dissolved material and the biomass crushed material are mixed in a weight ratio of biomass heavy oil to biomass of 10-20:70-80.

6. The method for preparing biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step b), the drying temperature is 80-100° C., and the drying time is 600-720 min.

7. The method for preparing biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step b), the amount of water added is 5-10% of the total weight of the biomass fragments.

8. The method for preparing biomass-heavy oil composite synergistic biomass briquette fuel according to claim 7, characterized in that: In step b), water is added dropwise in a dropwise manner.

9. The method for preparing biomass-heavy oil composite synergistic biomass briquette fuel according to claim 1, characterized in that: In step c), the biomass crushed material is cold pressed under a pressure of 10 to 20 MPa.

10. Biomass-heavy oil composite synergistic biomass shaped fuel, prepared by the preparation method according to any one of claims 1 to 9.

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