End face directional whitening control method for producing chrysanthemum charcoal

Abstract

The invention relates to a biomass pyrolysis and charcoal material surface densification control technology, in particular to an end face directional whitening control method for chrysanthemum charcoal production, which specifically comprises the following steps: in a sectional box body, deeply carbonizing wood with uniform end face orientation; unlocking and whitening after the core-surface temperature difference delta T is judged to be less than or equal to 25 DEG C through multi-point temperature measurement and model estimation; in the whitening stage, an end face annular flow guide and radiation heat exchange coupling structure is adopted, the temperature in the box is increased to 850-950 / 1000 DEG C from 520 + / -20 DEG C at the speed of 10-18 DEG C / min, and O is controlled to be 5-9 vol%, the box pressure is 20-80 Pa, and the end face cross-flow wind speed is 2.0-4.0 m / s; and coating 1-3mm of ash within 0-180 seconds after whitening is finished, and then performing inert cooling to be within 450 DEG C under the condition that O is less than or equal to 3%. O / box pressure / flame detection / temperature four-interlocking and door area front chamber inerting are arranged. According to the method, the proportion and whiteness stability of the chrysanthemum grains can be remarkably improved, bursting and collapsing are reduced, the whitening time is shortened, and energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of emerging energy technology, in particular to a method for producing chrysanthemum carbon by directional whitening of end face. BACKGROUND

[0002] Biomass carbonization has key significance in environmental protection, agriculture, energy and other fields. Chrysanthemum carbon is a high-quality white carbon product of biomass carbonization, which is named because its end face presents a radial or ring-shaped "chrysanthemum pattern", and it has high ornamental value and use value.

[0003] In the traditional production process of chrysanthemum carbon, whitening is usually carried out under the condition of uniform heating of the whole box, and the oxygen enrichment ratio and air volume are controlled in a rough way. The end face is not uniformly heated and oxygenated, the whiteness is discrete, and the cracking rate is high. SUMMARY

[0004] The embodiment of the present application provides a method for producing chrysanthemum carbon by directional whitening of end face, which is beneficial to solve the problems of uneven whiteness and high cracking rate in the prior art.

[0005] The first aspect provides a method for producing chrysanthemum carbon by directional whitening of end face, comprising: Loading step: loading wood end face uniformly into a sectional box; Deep carbonization step: deep carbonization treatment is performed on the wood in the sectional box, and the temperature difference ΔT between the core and the surface of the wood is monitored by multi-point temperature measurement and model estimation; Transheating determination step: when ΔT≤25℃, it is determined that the transheating is completed, and the whitening stage is unlocked; End face directional whitening step: whitening treatment is carried out by adopting end face ring-shaped flow guiding and radiation heat exchange coupling mode; Ash covering step: covering a 1-3 mm thick ash layer within 0-180 seconds after whitening is completed; Inert cooling step: inert cooling to below 450℃ under the condition of oxygen concentration ≤3%; Safety interlocking step: setting oxygen concentration, box pressure, flame detection, temperature four interlocking protection, and inerting the door area antechamber.

[0006] Optionally, when whitening treatment is carried out by adopting end face ring-shaped flow guiding and radiation heat exchange coupling mode, the specific control parameters are as follows: Temperature rising rate: 10-18℃ / min, the temperature in the box is raised from 520±20℃ to 850-1000℃; Oxygen concentration: 5-9 vol%; Box pressure: -20 to -80 Pa; End face through-flow air speed: 2.0-4.0 m / s.

[0007] Optionally, when ΔT(core-surface)≤25 ℃ enters whitening, O2=5–9 vol%, box pressure−20~−80 Pa, end face through flow 2.0–4.0 m / s, temperature rise rate 10–18 ℃ / min, whitening end 0–180 s covering 1–3 mm and in O2≤3% inert cooling to 450 ℃ within.

[0008] Optionally, the inner diameter of the annular fairing is 1.3–1.6 times the equivalent diameter of the end face. Optionally, the gap between the radiation member and the end face is 80–140 mm.

[0009] Optionally, the ΔT threshold is adaptively adjusted by 10–30 ℃ according to the material diameter. Optionally, the time of the inert cooling stage 900→450 ℃ is ≤120 min.

[0010] The temperature rise rate is preferably 12–16 ℃ / min.

[0011] Optionally, the oxygen concentration is preferably controlled at 6–8 vol%.

[0012] Optionally, the box pressure is preferably controlled at−35 to−60 Pa.

[0013] Optionally, the end face through flow wind speed is preferably 2.5–3.5 m / s.

[0014] Optionally, the inner diameter of the annular fairing is preferably 1.35–1.55 times the equivalent diameter of the end face.

[0015] Experiments have found that the technical scheme of the present application can significantly improve the quality of chrysanthemum patterns. Through the end face directional flow field and uniform radiation heat transfer, the formation rate of chrysanthemum patterns is increased by more than 30%, and the texture clarity and consistency are significantly improved.

[0016] The whiteness stability of the technical scheme of the present application is greatly improved: the end face whiteness uniformity is improved, and the whiteness coefficient of variation is reduced by more than 40%.

[0017] The technical scheme of the present application can significantly reduce the burst rate: through the core-penetrating heat criterion and accurate temperature rise rate control, the burst rate is reduced by more than 60%.

[0018] The technical scheme of the present application can improve the production efficiency: the whitening time is shortened by 15–25%, and the overall production rhythm is accelerated.

[0019] The technical scheme of the present application can reduce energy consumption: the optimized heat transfer mode and rapid cooling strategy can reduce the energy consumption per unit product by more than 20%.

[0020] The technical scheme of the present application can make the product consistency good: through multi-parameter coordinated control and safety interlocking, the quality stability between product batches is significantly improved.

[0021] The technical scheme of the present application can make the safety high: four interlockings and inert protection ensure the safety and reliability of the production process. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is a section view of a white section end surface annular flow guide and radiation coupling device of a tunnel kiln provided by the embodiments of the present application.

[0024] Figure 2 is a position relationship diagram of a radiation coupling device provided by the embodiments of the present application.

[0025] Figure 3 is a temperature control curve diagram provided by the embodiments of the present application Figure 4 is a safety interlocking timing diagram of E section provided by the embodiments of the present application. DETAILED DESCRIPTION

[0026] In order to make the person skilled in the art better understand the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on some embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0027] The terms "first", "second" and "third" and the like appearing in the specification, claims and drawings of the present application are used to distinguish different objects, and are not used to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system or product or device including a series of steps or units is not limited to the listed steps or units, and can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0028] The present application inventors found that the traditional oxygen-rich production process is carried out under the condition of whole-box uniform heating, the oxygen-rich ratio and air volume control are rough, the end face is unevenly heated and oxygenated, the whiteness is discrete, and the burst rate is relatively high. In the traditional one-way convection production process, through one-sided air supply, through convection is formed, but there are problems of local overheating of the end face and obvious disturbance of the box pressure, and it is difficult to control ΔT under different material diameters, which easily leads to "core focus" or insufficient whitening. In the traditional process related to only burning non-condensed gas NCG for heating, there are problems of large fluctuation of heating value and insufficient temperature climbing speed, which further easily causes the whitening peak to be unable to be stably maintained, etc., affecting the consistency of product quality. In addition, the traditional process generally lacks accurate determination of the "core heat" state of wood, often relying on experience to enter the whitening stage, leading to insufficient or excessive carbonization of the core, affecting the formation of the chrysanthemum pattern and the uniformity of whiteness of the final product.

[0029] Therefore, the present application inventors expect to develop a chrysanthemum carbon production method capable of accurately controlling the carbonization and whitening process, improving the chrysanthemum pattern quality and whiteness stability, reducing the burst rate, and at the same time shortening the production cycle and reducing energy consumption.

[0030] Firstly, some key technical terms are introduced.

[0031] Chrysanthemum pattern: refers to the radial or ring-shaped light and dark texture of the wood end face after whitening, which is the visual result of the coupling of radial thermal stress and surface densification, and is used to evaluate the end face aesthetics and consistency.

[0032] Metallic acoustic peak: refers to the high-frequency crisp acoustic response of the end face when the whitening is completed or close to completion, and the frequency domain peak is relatively shifted upward compared with the carbonization and non-whitening state; it can be used as one of the online or sampling criteria.

[0033] End face equivalent diameter (Deq): refers to the diameter of the equivalent circle of the end face projection area, or the diameter of the circumscribed circle of the end face, which is used to determine the size of the ring-shaped fairing.

[0034] ΔT(core-surface): refers to the difference between the core temperature and the surface temperature of the loaded wood; it is obtained by multi-point temperature measurement and model estimation, and is used as the release criterion for entering the whitening stage.

[0035] The scheme of the present application is specifically introduced as follows.

[0036] A method for producing chrysanthemum carbon, which can include: Loading step: uniformly loading the end face of the wood into a sectional box; Deep carbonization step: deep carbonization treatment is performed on the wood in the sectional box, and the temperature difference ΔT between the core and the surface of the wood is monitored by multi-point temperature measurement and model estimation; Core heat determination step: when ΔT≤25℃, it is determined that the core heat is completed, and the whitening stage is unlocked. End face orientation whitening step: whitening treatment is performed in an end face annular flow guiding and radiation heat exchange coupling mode; Ash covering step: an ash layer with a thickness of 1-3 mm is covered within 0-180 seconds after whitening is completed; Inert cooling step: inert cooling to 450℃ or below under the condition of oxygen concentration ≤3%; Safety interlocking step: four interlocking protections of oxygen concentration, box pressure, flame detection and temperature are set, and the door area antechamber is inerted.

[0037] Optionally, when whitening treatment is performed in an end face annular flow guiding and radiation heat exchange coupling mode, the specific control parameters are as follows: Temperature rising rate: 10-18℃ / min, the temperature in the box is raised from 520±20℃ to 850-1000℃; Oxygen concentration: 5-9 vol%; Box pressure: -20 to -80 Pa; End face through-flow wind speed: 2.0-4.0 m / s.

[0038] Optionally, when ΔT(core-surface) ≤25℃ enters whitening, O2=5–9 vol%, box pressure−20~−80Pa, end face through-flow 2.0–4.0 m / s, temperature rising rate 10–18 ℃ / min, 0–180 s ash covering 1–3 mm after whitening is completed, and O2≤3% inert cooling to 450℃ or below.

[0039] Optionally, the inner diameter of the annular flow guide cover is 1.3-1.6 times the equivalent diameter of the end face. Optionally, the gap between the radiation member and the end face is 80-140 mm.

[0040] Optionally, the ΔT threshold is adaptively adjusted by 10-30 ℃ according to the material diameter. Optionally, the inert cooling stage time from 900 to 450℃ is ≤120 min.

[0041] The temperature rising rate is preferably 12-16℃ / min.

[0042] Optionally, the oxygen concentration is preferably controlled at 6-8 vol%.

[0043] Optionally, the box pressure is preferably controlled at -35 to -60 Pa.

[0044] Optionally, the end face through-flow wind speed is preferably 2.5-3.5 m / s.

[0045] Optionally, the inner diameter of the annular flow guide cover is preferably 1.35-1.55 times the equivalent diameter of the end face.

[0046] Referring to Figure 1 , Figure 1 The white section end face annular flow guide and radiation coupling device provided by the embodiment of the application can include an outer ring flow guide cover 1, an inner side radiation component 4, and a plurality of adjustable flow guide vanes 3.

[0047] It can also include an annular flow guide channel 2, a temperature probe interface 5, and a flange 6 for connecting a seal.

[0048] 7 is a blank end face, and 8 is a kiln wall / air supply port.

[0049] The outer ring flow guide cover is in communication with the air supply port of the kiln body to form a closed annular flow guide channel, the inner diameter of the outer ring flow guide cover is 1.3-1.6 times the equivalent diameter of the blank, and the annular gap width is 80-140 mm; the outer ring flow guide cover is integrally formed from stainless steel or high-silicon oxide ceramic material, and the inner wall is provided with a 0.5-1.5 mm thick anti-dust coating.

[0050] The inner side radiation component is coaxially arranged on the inner side of the outer ring flow guide cover and is arranged opposite the blank end face, and the center distance between the two is 120-200 mm; the radiation component is made of high-temperature-resistant alloy or silicon carbide ceramic, and the surface is coated with a high-emissivity oxide layer. The plurality of adjustable flow guide vanes are uniformly distributed in the annular flow guide channel, the vanes are installed in a hinged manner and are provided with a wear-resistant coating on the edge, and the angle is adjusted in real time through an external adjusting mechanism within a range of 10-35°.

[0051] Figure 2 The E section end face annular flow guide and radiation layout is shown, and the relative positional relationship between the annular flow guide cover, the radiation component, and the wood end face is shown.

[0052] Figure 3 It is a whole temperature control curve schematic diagram. The temperature change curve of each stage (B→C→D→E→F) from loading, preheating, carbonization, whitening to cooling is shown.

[0053] Figure 4 It is an E section safety interlocking timing schematic diagram, and an optional logical relationship and triggering condition of four interlocks of oxygen, tank pressure, flame detection, and temperature are shown.

[0054] It is found through experiments that the technical solution of the application can significantly improve the chrysanthemum pattern quality. Through the end face directional flow field and uniform radiation heat exchange, the formation rate of the chrysanthemum pattern is increased by more than 30%, and the texture clarity and consistency are obviously improved.

[0055] The whiteness stability of the technical solution of the application is greatly improved: the end face whiteness uniformity is improved, and the whiteness variation coefficient is reduced by more than 40%.

[0056] The technical solution of the present application can significantly reduce the blasting rate: through the core heat criterion and accurate heating rate control, the blasting rate is reduced by more than 60%.

[0057] The technical solution of the present application can improve production efficiency: the whitening time is shortened by 15-25%, and the overall production rhythm is accelerated.

[0058] The technical solution of the present application can reduce energy consumption: the optimized heat exchange mode and rapid cooling strategy can reduce the energy consumption per unit product by more than 20%.

[0059] The technical solution of the present application can ensure good product consistency: through multi-parameter collaborative control and safety interlocking, the quality stability between product batches is significantly improved.

[0060] The technical solution of the present application can ensure high safety: four interlocks and inert protection ensure the safety and reliability of the production process.

[0061] Experiments have found that the technical solution of the present application is based on the soft measurement technology of ΔT (core-surface), which ensures that the wood reaches the "core heat" state before entering the whitening stage through multi-point temperature measurement and model estimation, avoiding quality problems caused by insufficient carbonization of the core.

[0062] End face annular flow guide and radiation coupled heat exchange: in the whitening section, the end face is organized to flow orthogonally through the annular flow guide cover, and radiation members (radiation pipes or radiation plates) are arranged on the inner side. The total heat transfer coefficient at the end face can be expressed as: htotal = hconv + hrad Where hconv is determined by the end face flow speed and the flow guide blade angle, and hrad is related to the radiation member temperature and the view angle coefficient.

[0063] The technical solution of the present application is precise multi-parameter collaborative control: by controlling the end face flow speed to be 2.0-4.0 m / s, the convective heat transfer coefficient hconv is maintained in a stable interval; at the same time, the radiation member provides uniform radiation flux, reduces the end face temperature difference, and suppresses local hot spots and uneven vitrification.

[0064] The technical solution of the present application is a phased fine control strategy: Whitening heating rate: 10-18 ℃ / min Oxygen content control: 5-9 vol%, used to control the surface oxidation rate and vitrification process Box pressure maintenance: -20 to -80 Pa, to prevent external air from being sucked in Rapid ashing: 1-3 mm of ashing within 0-180 seconds after whitening Inert cooling: complete 900→450℃ rapid cooling within ≤120 minutes under the condition of O2≤3% The technical solution of the application has a four-safety interlocking mechanism: setting O2 / box pressure / fire detection / temperature four interlocking and door area front chamber inerting to ensure production safety.

[0065] Several specific parameter configuration scenarios are introduced below.

[0066] Example 1 (reference process): The following process parameters are used in this example: Loading stage: 1.15 t / pallet, wood porosity 40%, end face uniform orientation; Deep carbonization stage (D section): monitor ΔT by multi-point temperature measurement, when ΔT decreases from 38℃ to 22℃ and maintains for 15 minutes, it is determined that the full heart heat is completed, and the white stage is entered; White stage (E section): Ramp-up rate: 14℃ / min Oxygen concentration: 6.5-7.5 vol% Box pressure: -45 Pa End face through-flow wind speed: 2.8 m / s Peak temperature: 905℃ Soaking time: 45 minutes Ash covering 1.8 mm; Inert cooling 900→450 ℃ for 98 min.

[0067] Experimental results: chrysanthemum pattern is clear and complete, accounting for more than 85% of the end face; whiteness is uniform, L value is 78±3; burst rate <2%; single batch energy consumption is reduced by 22% compared with traditional process.

[0068] Example 2 (low peak / high soaking process): This example is suitable for large diameter or high loading conditions.

[0069] White stage (E section): Peak temperature: 870℃ Soaking time: 60 minutes Oxygen concentration: 5-6 vol% End face through-flow wind speed: 2.2-2.8 m / s Ash covering: thickness 1.0-1.5 mm; Inert cooling: 110-120 minutes from 900℃ to 450℃.

[0070] Experimental results: suitable for large diameter wood with diameter >150mm, chrysanthemum pattern formation rate 82%, burst rate <3%, whiteness L value 76±4.

[0071] Example 3 (high peak / short soaking process): This example is suitable for rapid beat production of small and medium diameter materials: White stage (E section): Peak temperature: 960°C Soaking time: 25-35 minutes Oxygen concentration: 7-8.5 vol% End face through-flow air speed: 3.0-3.6 m / s Dust covering: thickness 2-3 mm Inert cooling: 85-95 minutes from 900°C to 450°C.

[0072] Experimental results: production rhythm shortened by 30%, chrysanthemum pattern formation rate 88%, whiteness L value 80±2, burst rate <1.5%.

[0073] Example 4 (boundary ΔT process): Deep carbonization stage: ΔT threshold set to 30°C, limited speed temperature rise extended to 6.5-7 hours, observation window increased to 20-25 minutes before release; Whitening stage: temperature rise rate reduced to 10-12°C / min, reduce thermal stress, reduce burst risk.

[0074] Experimental results: for ultra-large material diameter >180mm, burst rate controlled within 2%, chrysanthemum pattern formation rate 80%.

[0075] Example 5 (inert cooling enhancement process): this example is aimed at optimization of the inert cooling stage: Trigger alarm when O2 concentration >1.5%, inert gas flow automatically increased by 30-50%, O2 concentration controlled at ≤1%; Fast cooling: reduced to ≤90 minutes from 900°C to 450°C.

[0076] Experimental results: rekindling risk reduced to near zero, product surface oxidation layer thickness reduced by 40%, whiteness further improved.

[0077] The following is a comparison table of example ranges of relevant parameters:

[0078] The above is only some specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for end face oriented whitening control for producing chrysanthemum charcoal, characterized by, Comprise: Loading step: loading the wood into the section box with the end faces uniformly oriented; Deep carbonization step: deep carbonization treatment is performed on the wood in the section box, and the temperature difference ΔT between the core and the surface of the wood is monitored by multi-point temperature measurement and model estimation; Heart-penetration heat determination step: when ΔT≤25 ℃, it is determined that the heart-penetration heat is completed, and the white stage is unlocked; End face orientation whitening step: whitening treatment is performed by using end face annular flow guiding and radiation heat coupling mode; Ash covering step: after whitening, a 1-3 mm thick ash layer is covered within 0-180 seconds; Inert cooling step: under the condition that the oxygen concentration is ≤3%, inert cooling is performed to below 450 ℃; Safety interlocking step: four interlocking protections of oxygen concentration, box pressure, flame detection and temperature are set, and the door area antechamber is inerted.

2. The method of claim 1, wherein, When the end face annular flow guiding and radiation heat coupling mode is used for whitening treatment, the specific control parameters are as follows: Rising rate: 10-18 ℃ / min, the temperature in the box is raised from 520±20 ℃ to 850-1000 ℃; Oxygen concentration: 5-9 vol%; Box pressure: -20 to -80 Pa; End face through-flow wind speed: 2.0-4.0 m / s.

3. The method of claim 1, wherein, When ΔT(core-surface)≤25 ℃, whitening is entered, O2=5–9 vol%, box pressure−20~−80 Pa, end face through-flow 2.0–4.0 m / s, rising rate 10–18 ℃ / min, ash covering 1–3 mm within 0–180 s after whitening, and O2≤3% inert cooling to below 450 ℃.

4. The method according to any one of claims 1 to 3, characterized in that, The inner diameter of the annular flow guiding cover is 1.3-1.6 times the equivalent diameter of the end face.

5. The method according to any one of claims 1 to 3, characterized in that, The gap between the radiation member and the end face is 80-140 mm.

6. The method according to any one of claims 1 to 3, characterized in that, The ΔT threshold is adaptively adjusted by 10-30 ℃ according to the diameter.

7. The method according to any one of claims 1 to 3, characterized in that, The time of the inert cooling stage 900→450 ℃ is ≤120 min.

8. The method according to any one of claims 1 to 3, characterized in that, The rising rate is preferably 12-16 ℃ / min.

9. The method according to any one of claims 1 to 3, characterized in that, The oxygen concentration is preferably controlled at 6-8 vol%.

10. The method according to any one of claims 1 to 3, characterized in that, The box pressure is preferably controlled at -35 to -60 Pa.

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