Method for preparing high-concentration gasified coal water slurry from full coal slime and special composite additive

Abstract

The invention relates to the technical field of clean utilization of coal, in particular to a method for preparing high-concentration gasified coal water slurry from full coal slime and a special composite additive. The composite additive is formed by compounding a dispersing agent and a stabilizing agent according to the mass ratio of 1: 1-2: 1, the dispersing agent comprises sodium lignin sulfonate, sodium poly (naphthaleneformaldehyde) sulfonate and sodium polystyrenesulfonate, and the stabilizing agent comprises polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose. The preparation method comprises the following steps: grading coal slime, and mixing with water; performing ultrasonic treatment on the slurry; and adding the composite additive accounting for 0.2-0.5% of the mass of the dry basis coal slime, and stirring to obtain the coal slime. Through the synergistic effect of ultrasonic treatment and the composite additive, the contradiction between high viscosity and poor stability during slurry forming of the coal slime is solved, and the prepared coal water slurry is high in concentration (greater than or equal to 64%), low in viscosity (600-1200 mPa.s) and good in stability (72 h drainage rate lt: 5%), and is particularly suitable for gasification raw materials.

Description

Technical Field

[0001] This invention relates to the field of clean utilization technology of coal resources, specifically to a composite additive for improving the slurry-forming properties of coal slime, and a method for preparing high-concentration, high-stability coal-water slurry using the composite additive. Background Technology

[0002] Coal slime is a major byproduct of coal washing and processing, characterized by high moisture content, high ash content, fine particle size, and easy agglomeration. With the increasing proportion of coal being processed, the production of coal slime is enormous. Its accumulation and disposal not only occupies land but also causes environmental pollution and resource waste. Preparing coal slime into high-concentration coal-water slurry is an important direction for achieving its clean and efficient utilization.

[0003] However, the inherent physicochemical properties of coal slime pose significant challenges during the slurry formation process. The core issue lies in the difficulty of simultaneously obtaining a high-concentration, low-viscosity, and long-term stable slurry. Several attempts have been made in existing technologies, but each has its own limitations: For example, patent document CN109913281A discloses a "method for preparing sodium lignosulfonate dispersant and coal slurry," which uses papermaking waste liquor to prepare sodium lignosulfonate dispersant and uses it in combination with naphthalene-based dispersants. Although this method utilizes industrial by-products to some extent, its additive system still focuses on dispersibility, has limited improvement on the long-term stability of the slurry, and does not involve deep pretreatment of the coal slurry particles themselves, making it difficult to achieve high-concentration coal slurry.

[0004] Patent document CN101373071A discloses a "method for preparing coal-water slurry using coal slime," which advocates directly using coal slime and omitting the crushing step to simplify the process. However, this technical solution is too simple and lacks an effective additive system and particle size control, resulting in generally low concentrations of the prepared coal-water slurry (usually difficult to stably exceed 63%), which cannot meet the stringent requirements of modern fluidized bed gasifiers for high concentrations of raw coal-water slurry.

[0005] Patent document CN101270309B proposes "preparing coal-water slurry using virgin coal slime and sodium lignosulfonate powder." This method combines coal slime and papermaking wastewater, emphasizing waste utilization. However, its core technology is still simple mechanical mixing, and the additive used is singular (only sodium lignosulfonate), resulting in a high viscosity (814-1221 mPa·s) and poor fluidity of the finished coal-water slurry, which is not conducive to industrial pumping and atomization.

[0006] Regarding equipment, patent document CN211339411U provides a "novel coal slime to coal slurry device" that improves efficiency by optimizing the equipment process. However, this utility model patent mainly addresses the issues of equipment layout and process continuity, without fundamentally breaking through the key technology of chemical additives for coal slime slurry formation. It offers limited help in resolving the inherent contradiction between the dispersion and stability of coal slime particles.

[0007] Furthermore, patent document CN114350420B relates to a "low-cost method for preparing coal slime-based coal-water slurry," which employs a method of blending coal slime with raw coal and applying strong shearing to attempt to optimize particle size distribution through physical means. However, this method requires the introduction of high-quality raw coal and is not a pure coal slime utilization technology. Moreover, its additive system fails to effectively solve the problem of poor slurry-forming properties caused by high-ash coal slime. Therefore, this method fails to achieve the core objective of preparing high-quality coal-water slurry using whole coal slime as raw material.

[0008] Patent document CN110218594B aims to solve the problem of "preparing gasification-type coal-water slurry from high ash melting point coal slime" by adjusting the ash melting point through the addition of low ash melting point coal and special additives. The key point of this technology is to meet the liquid slag discharge requirements of the gasifier, but its technical solution is complex and is not the optimal solution for the common slurry-forming problems of conventional non-high ash melting point coal slime (such as the balance between viscosity and stability).

[0009] In addition, although patent document CN106047426B achieves deep deashing and desulfurization of coal slime through a complex "flotation" process and prepares "low-ash and low-sulfur coal-water slurry", the process route is long, the process is complex, the reagent consumption is large, and the investment and operating costs are high, making it difficult to promote and apply in large-scale coal slime disposal projects that pursue economic efficiency.

[0010] In summary, existing technologies either focus on simple physical mixing or equipment improvements, failing to fundamentally solve the chemical-physical synergistic problem of coal slime slurry formation; or they employ overly complex and expensive pretreatment processes, resulting in poor economic efficiency. Their common core deficiency lies in the lack of a dedicated composite additive system that can synergistically act on coal slime particles to achieve efficient dispersion and viscosity reduction while significantly enhancing slurry stability, as well as a highly compatible pretreatment process that can effectively activate the surface of coal slime particles.

[0011] Therefore, developing a new type of coal slime composite additive and a corresponding efficient slurry preparation method is of great significance for breaking through the technical bottleneck of high-value utilization of coal slime. Summary of the Invention

[0012] In view of the above-mentioned technical problems in the existing technology, and in order to overcome the shortcomings of the existing technology, the present invention aims to provide a method for preparing high-concentration gasified coal-water slurry from whole coal slime and a special composite additive, thereby solving the shortcomings of the existing technology.

[0013] This invention provides a method for preparing high-concentration coal-water gasification slurry from whole coal slime, comprising the following steps: (1) Coal slime classification: The pretreated coal slime with a moisture content of 20-30% is classified and the particle size distribution is controlled as follows: 5%-10% of particles above 20 mesh, 40%-55% of particles above 40 mesh, 5%-15% of particles above 220 mesh, and 25%-35% of particles above 340 mesh; (2) Mixing and slurry preparation: The graded coal slime and water are added into the mixing equipment at a mass ratio of 0.83-0.9:0.1-0.17 and mixed for 20-50 minutes to obtain graded coal slime slurry; (3) Ultrasonic nano-processing: The graded coal slurry is subjected to ultrasonic treatment with an ultrasonic frequency of 20kHz-60kHz and a power density of 300W / L-800W / L. (4) Add composite additive and stir: Add coal slime composite additive to the slurry after ultrasonic treatment. The composite additive consists of dispersant and stabilizer, and the total amount added is 0.2%-0.5% of the dry coal slime mass. Stir for 30min-60min at a speed of 500r / min-1200r / min to obtain the high-concentration gasified coal-water slurry.

[0014] As a further technical solution of the present invention: in step (3), the ultrasonic treatment is intermittent or continuous, the single treatment time is 3-15 min, and a total of 1-3 treatments are performed. During the treatment, the slurry temperature is controlled at 25℃-50℃.

[0015] As a further technical solution of the present invention: the mass ratio of the dispersant to the stabilizer is 1:1 to 2:1.

[0016] As a further technical solution of the present invention: the dispersant comprises sodium lignosulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate.

[0017] As a further technical solution of the present invention: the mass ratio of sodium lignin sulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate is (1~1.5):1:(1~2).

[0018] As a further technical solution of the present invention: the stabilizer comprises polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose.

[0019] As a further technical solution of the present invention: the mass ratio of polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose is (1~2):1:(1~1.5).

[0020] As a further technical solution of the present invention: In step (3), during the ultrasonic treatment process, the temperature of the slurry is controlled at 25℃-50℃ by a temperature control system with a control accuracy of ±1℃.

[0021] As a further technical solution of the present invention: the concentration of the coal-water slurry prepared by the above method is not less than 64%, the apparent viscosity is 600mPa·s-1200mPa·s, and the water separation rate is less than 5% after standing for 72 hours.

[0022] The present invention also provides a special composite additive for preparing high-concentration coal-water slurry for gasification from whole coal slime, characterized in that it is composed of a dispersant and a stabilizer, wherein the mass ratio of the dispersant to the stabilizer is 1:1 to 2:1; the dispersant is a mixture of sodium lignosulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate; and the stabilizer is a mixture of polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose.

[0023] Furthermore: the mass ratio of sodium lignosulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate is (1~1.5):1:(1~2); the mass ratio of polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose is (1~2):1:(1~1.5).

[0024] This invention aims to solve: The purpose of this invention is to overcome the shortcomings of existing coal slime additives, such as poor dispersion and insufficient stability, and to provide a composite coal slime additive that effectively improves the dispersibility of coal slime particles and enhances the stability of coal slime slurry, thereby preparing high-concentration coal-water slurry for gasification. Furthermore, this invention also provides a method for preparing high-concentration coal-water slurry using this composite additive. This method is simple, convenient, and suitable for industrial production.

[0025] The core technical solution of this invention is as follows: A complete technical system for synergistic optimization of "process and additives" is provided to solve the problem of high-concentration coal slime slurry formation. This system comprises two mutually supportive and indispensable core components: 1. Special coal slime composite additive: This invention creatively combines specific types and proportions of dispersants (such as sodium lignosulfonate, sodium polynaphthalene sulfonate, and sodium polystyrene sulfonate) and stabilizers (such as polyvinyl alcohol, polyacrylamide, and carboxymethyl cellulose). Through the synergistic effect of each component, while achieving efficient dispersion and reducing viscosity, it significantly enhances the long-term stability of the slurry, overcoming the inherent contradiction that single-function additives cannot simultaneously achieve both dispersibility and stability. 2. Matching Ultrasonic Pretreatment Process: This invention introduces a key step of ultrasonic nano-treatment before adding composite additives. This process, through its unique cavitation effect, can further break down coal slime particles and increase their specific surface area, thereby "activating" the surface of the coal slime particles and creating optimal conditions for the efficient adsorption and action of subsequent composite additives.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. Synergistic Effect Mechanism: This invention is not a simple superposition of dispersants and stabilizers, but rather achieves a synergistic effect through specific component combinations and ratio control. Dispersants effectively break down the agglomeration structure between coal slime particles, reducing slurry viscosity; while stabilizers, through steric hindrance and thickening effects, prevent the dispersed particles from re-aggregating and settling. This invention, by optimizing the ratio, achieves a dynamic balance between these two seemingly contradictory effects (viscosity reduction and stability enhancement), thereby simultaneously achieving high concentration (high solids content at low viscosity) and high stability. 2. Synergy between process and additives: This invention creatively combines ultrasonic nano-processing with the use of composite additives. The cavitation effect of ultrasound can further break down coal slime particles, exposing more fresh surfaces, which greatly increases the adsorption sites of additive molecules on the surface of coal slime particles. This allows the dispersion and stabilization performance of the composite additives to be fully utilized, producing an unexpected technical effect of "1+1>2". 3. Significant technological advancements: As shown in the example data, the water-coal slurry prepared by this invention has a stable concentration of over 64%, an apparent viscosity suitable for industrial pumping (600-1200 mPa·s), and an extremely low water separation rate (<5%) after 72 hours. All key performance indicators are superior to those of the comparative example with a single additive, fully meeting the stringent requirements of modern fluidized bed gasifiers for raw water-coal slurry. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Common raw materials and conditions: The examples and comparative examples in this section all use coal slime raw materials from the same source, which comes from a coal preparation plant and has a moisture content of approximately 25% after pretreatment. The coal slime is graded using a vibrating screen to control its particle size distribution as follows: approximately 8% of the material passing through a 20-mesh screen, approximately 50% passing through a 40-mesh screen, approximately 10% passing through a 220-mesh screen, and approximately 32% passing through a 340-mesh screen. "Passage through the screen" refers to particles that fail to pass through the screen of that mesh size, i.e., particles with a diameter larger than the screen aperture.

[0029] Example 1: The mass ratio of dispersant to stabilizer is 1:1, and the total amount of additives is 0.25%.

[0030] Sodium lignosulfonate, sodium polynaphthalene sulfonate, and sodium polystyrene sulfonate were weighed and mixed in a mass ratio of 1:1:1 to serve as a dispersant. Polyvinyl alcohol, polyacrylamide, and carboxymethyl cellulose were weighed and mixed in a mass ratio of 2:1:1.5 to serve as a stabilizer. The above dispersant and stabilizer were mixed evenly in a total mass ratio of 1:1 to obtain the coal slime composite additive of the present invention.

[0031] Take 1000 grams (dry basis weight) of the graded coal slime and add it to a mixer with 150 grams of water. Mix at 400 r / min for 30 minutes to obtain a uniformly graded coal slime slurry.

[0032] The obtained slurry was fed into an ultrasonic nano-sizing device, with the ultrasonic frequency set to 40kHz and the power density to 500W / L for ultrasonic treatment. The treatment method was as follows: a single treatment time of 10 minutes, followed by a 2-minute cooling interval, and this cycle was repeated twice. Throughout the ultrasonic treatment process, the slurry temperature was maintained at (40±1)℃ using a temperature control system to obtain nano-sized coal slime slurry.

[0033] Add 2.5 grams of the composite additive prepared above (accounting for 0.25% of the dry coal slime mass) to the nano-grade coal slime slurry, increase the speed of the mixer to 800 r / min, and continue stirring for 40 minutes to obtain a high-concentration coal-water slurry product.

[0034] The performance of the coal-water slurry product was tested: its apparent viscosity was 1172 mPa·s after standing for 20 minutes; and its water separation rate was 3.9% after standing for 72 hours.

[0035] Example 2: The mass ratio of dispersant to stabilizer is 1:1, and the total amount of additives is 0.35%.

[0036] Except for adjusting the total amount of composite additives to 0.35% of the dry coal slime mass (i.e., adding 3.5 grams), the remaining steps, raw materials and process parameters are exactly the same as in Example 1.

[0037] The properties of the prepared coal-water slurry product are: apparent viscosity 981 mPa·s, and water separation rate of 3.8% after 72 hours.

[0038] Example 3: The mass ratio of dispersant to stabilizer is 1:1, and the total amount of additives is 0.45%.

[0039] Except for adjusting the total amount of composite additives to 0.45% of the dry coal slime mass (i.e., adding 4.5 grams), the remaining steps, raw materials, and process parameters are exactly the same as in Example 1.

[0040] The properties of the prepared coal-water slurry product are: apparent viscosity 793 mPa·s, and water separation rate of 3.2% after 72 hours.

[0041] Example 4: The mass ratio of dispersant to stabilizer is 1.5:1, and the total amount of additives is 0.25%.

[0042] Except for adjusting the total mass ratio of dispersant to stabilizer in the composite additive to 1.5:1, the other steps, raw materials and process parameters are exactly the same as in Example 1.

[0043] The properties of the prepared coal-water slurry product are: apparent viscosity 1096 mPa·s, and water separation rate of 4.1% after 72 hours.

[0044] Example 5: The mass ratio of dispersant to stabilizer is 1.5:1, and the total amount of additives is 0.35%.

[0045] Except for adjusting the total amount of composite additives to 0.35% of the dry coal slime mass (i.e., adding 3.5 grams), and the total mass ratio of dispersant to stabilizer to be 1.5:1, the remaining steps, raw materials and process parameters are exactly the same as in Example 1.

[0046] The properties of the prepared coal-water slurry product are: apparent viscosity 864 mPa·s, and water separation rate of 4.1% after 72 hours.

[0047] Example 6: The mass ratio of dispersant to stabilizer is 1.5:1, and the total amount of additives is 0.45%.

[0048] Except for adjusting the total amount of composite additives to 0.45% of the dry coal slime mass (i.e., adding 4.5 grams) and the total mass ratio of dispersant to stabilizer to 1.5:1, the remaining steps, raw materials and process parameters are exactly the same as in Example 1.

[0049] The properties of the prepared coal-water slurry product are: apparent viscosity 699 mPa·s, and water separation rate of 3.6% after 72 hours.

[0050] Example 7: The mass ratio of dispersant to stabilizer is 2:1, and the total amount of additives is 0.25%.

[0051] Except for adjusting the total mass ratio of dispersant to stabilizer in the composite additive to 2:1, the other steps, raw materials and process parameters are exactly the same as in Example 1.

[0052] The properties of the prepared coal-water slurry product are: apparent viscosity 974 mPa·s, and water separation rate of 4.4% after 72 hours.

[0053] Example 8: The mass ratio of dispersant to stabilizer is 2:1, and the total amount of additives is 0.35%.

[0054] Except for adjusting the total amount of composite additives to 0.35% of the dry coal slime mass (i.e., adding 3.5 grams) and the total mass ratio of dispersant to stabilizer to 2:1, the remaining steps, raw materials and process parameters are exactly the same as in Example 1.

[0055] The properties of the prepared coal-water slurry product are: apparent viscosity 811 mPa·s, and water separation rate of 4.5% after 72 hours.

[0056] Example 9: The mass ratio of dispersant to stabilizer is 2:1, and the total amount of additives is 0.45%.

[0057] Except for adjusting the total amount of composite additives to 0.45% of the dry coal slime mass (i.e., adding 4.5 grams), and the total mass ratio of dispersant to stabilizer to be 2:1, the remaining steps, raw materials and process parameters are exactly the same as in Example 1.

[0058] The properties of the prepared coal-water slurry product are: apparent viscosity 545 mPa·s, and water separation rate of 4.0% after 72 hours.

[0059] Comparative Examples 1-6: Comparison of Single Additives; For comparison, a single component was used as an additive, and the preparation process was the same as in Example 1.

[0060] Comparative Examples 1-3: The additive was sodium lignosulfonate, and the addition amount (dry basis coal slime mass) was 0.25%, 0.35%, and 0.45%, respectively.

[0061] Comparative Examples 4-6: The additive was polyvinyl alcohol, and the addition amount (dry basis coal slime mass) was 0.25%, 0.35%, and 0.45%, respectively.

[0062] To systematically demonstrate the influence of the ratio (D:S) of dispersant and stabilizer and the amount added in the composite additive of the present invention on the performance of coal-water slurry, the key data of Examples 1-9 are summarized in Tables 1 and 2 below.

[0063] Table 1. Apparent viscosity (mPa·s) of coal-water slurry prepared with different proportions of composite additives

[0064] Table 2. Water separation rate (%) of coal-water slurry prepared with different proportions of composite additives after 72 hours

[0065] As shown in the table above, the viscosity and stability of coal-water slurry can be precisely controlled by adjusting the overall ratio (D:S) and dosage of the composite additive. In summary, when the D:S ratio is 1.5:1 and the dosage is 0.35%-0.45%, it is possible to achieve lower viscosity (below 900 mPa·s) and good stability (water separation rate below 4.5%) while maintaining a concentration above 65%, thus achieving the best technical effect. This data fully demonstrates that the composite additive with the specific ratio of this invention solves the contradiction of "high concentration equals high viscosity, low viscosity equals poor stability" in coal slime slurry formation, achieving unexpected technical results.

[0066] The performance comparison results of the obtained coal-water slurry with those of the embodiments of the present invention are summarized in the table below.

[0067] Table 3. Comparison of the performance of coal-water slurry in the embodiments of the present invention and the comparative examples.

[0068] As shown in Table 3, the key performance indicators of coal-water slurry prepared using a single additive (Comparative Examples 1-6) are significantly inferior to those prepared using the composite additive of this invention (Examples 4-6) in terms of concentration, viscosity, and stability. In particular, under the same or similar additive dosages, the product of this invention maintains a high concentration (≥64.5%) while exhibiting lower apparent viscosity (≤1096 mPa·s) and better stability (72h water separation rate ≤4.5%), and higher fluidity. This fully demonstrates that this invention, through the combination of a specific ratio of composite additives and ultrasonic nano-processing, effectively solves the technical challenge of balancing dispersibility and stability when forming high-concentration coal slime slurries, achieving unexpected technical results.

[0069] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-concentration coal-water gasification slurry from whole coal slime, characterized in that, Includes the following steps: (1) Coal slime classification: The pretreated coal slime with a moisture content of 20-30% is classified and the particle size distribution is controlled as follows: 5%-10% of particles above 20 mesh, 40%-55% of particles above 40 mesh, 5%-15% of particles above 220 mesh, and 25%-35% of particles above 340 mesh; (2) Mixing and slurry preparation: The graded coal slime and water are added into the mixing equipment at a mass ratio of 0.83-0.9:0.1-0.17 and mixed for 20-50 minutes to obtain graded coal slime slurry; (3) Ultrasonic nano-processing: The graded coal slurry is subjected to ultrasonic treatment with an ultrasonic frequency of 20kHz-60kHz and a power density of 300W / L-800W / L. (4) Add composite additive and stir: Add coal slime composite additive to the slurry after ultrasonic treatment. The composite additive consists of dispersant and stabilizer, and the total amount added is 0.2%-0.5% of the dry coal slime mass. Stir for 30min-60min at a speed of 500r / min-1200r / min to obtain the high-concentration gasified coal-water slurry.

2. The method according to claim 1, characterized in that, In step (3), the ultrasonic treatment is intermittent or continuous, with a single treatment time of 3-15 minutes and a total of 1-3 treatments. During the treatment, the slurry temperature is controlled at 25℃-50℃.

3. The method according to claim 1 or 2, characterized in that, The mass ratio of the dispersant to the stabilizer is 1:1 to 2:

1.

4. The method according to claim 3, characterized in that, The dispersant comprises sodium lignosulfonate, sodium polynaphthalene sulfonate, and sodium polystyrene sulfonate.

5. The method according to claim 4, characterized in that, The mass ratio of sodium lignosulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate is (1~1.5):1:(1~2).

6. The method according to claim 3, characterized in that, The stabilizer comprises polyvinyl alcohol, polyacrylamide, and carboxymethyl cellulose.

7. The method according to claim 6, characterized in that, The mass ratio of polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose is (1~2):1:(1~1.5).

8. The method according to claim 3, characterized in that, In step (3), during the ultrasonic treatment process, the slurry temperature is controlled at 25℃-50℃ by a temperature control system with a control accuracy of ±1℃.

9. A high-concentration gasified coal-water slurry prepared by the method according to any one of claims 1-8, characterized in that, The concentration of the coal-water slurry is not less than 64%, the apparent viscosity is 600 mPa·s-1200 mPa·s, and the water separation rate is less than 5% after standing for 72 hours.

10. A composite additive specifically for preparing high-concentration coal-water slurry for gasification using whole coal slime, characterized in that, It consists of a dispersant and a stabilizer, with the mass ratio of dispersant to stabilizer being 1:1 to 2:1; the dispersant is a mixture of sodium lignosulfonate, sodium polynaphthalene sulfonate, and sodium polystyrene sulfonate; the stabilizer is a mixture of polyvinyl alcohol, polyacrylamide, and carboxymethyl cellulose.

11. The special composite additive according to claim 10, characterized in that, The mass ratio of sodium lignosulfonate, sodium polynaphthalene sulfonate and sodium polystyrene sulfonate is (1~1.5):1:(1~2); the mass ratio of polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose is (1~2):1:(1~1.5).

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