CN108955095B - A kind of microwave drying process of lignite - Google Patents
A kind of microwave drying process of lignite Download PDFInfo
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- 238000001035 drying Methods 0.000 title claims abstract description 200
- 239000003077 lignite Substances 0.000 title claims abstract description 162
- 239000002245 particle Substances 0.000 claims abstract description 98
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 47
- 230000005855 radiation Effects 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 11
- 238000005507 spraying Methods 0.000 claims description 5
- 238000001704 evaporation Methods 0.000 claims 1
- 230000008020 evaporation Effects 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 9
- 238000009825 accumulation Methods 0.000 description 6
- 238000001514 detection method Methods 0.000 description 6
- 239000003245 coal Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 4
- 239000012458 free base Substances 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000779 smoke Substances 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000002036 drum drying Methods 0.000 description 2
- 238000002309 gasification Methods 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
- F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
- F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B1/00—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B1/00—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids
- F26B1/005—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids by means of disintegrating, e.g. crushing, shredding, milling the materials to be dried
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
- F26B25/001—Handling, e.g. loading or unloading arrangements
- F26B25/002—Handling, e.g. loading or unloading arrangements for bulk goods
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- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Physics & Mathematics (AREA)
- Biomedical Technology (AREA)
- Biotechnology (AREA)
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- Health & Medical Sciences (AREA)
- Electromagnetism (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Drying Of Solid Materials (AREA)
Abstract
本发明涉及一种褐煤微波干燥工艺，是将褐煤颗粒含水量调控在40wt%～60wt%，先送入初段微波干燥室，以入射角60°～80°的微波进行初段微波干燥，使含水量降至20wt%～30wt%，再送入二段微波干燥室，以入射角40°～60°的微波干燥，使含水量降至10wt%以下。本发明采用微波场中分级脱除水分的方式，在对褐煤进行有效干燥的同时，能够有效抑制褐煤中挥发分的释放，极大降低了微波干燥褐煤时发生火灾的隐患。The invention relates to a microwave drying process for lignite, which is to control the moisture content of lignite particles at 40wt% to 60wt%, first send them into an initial stage microwave drying chamber, and carry out initial stage microwave drying with microwaves with an incident angle of 60° to 80°, so that the moisture content is reduced. It is reduced to 20wt% to 30wt%, and then sent to the second-stage microwave drying chamber, and dried by microwaves with an incident angle of 40° to 60° to reduce the water content to below 10wt%. The invention adopts the method of grading water removal in the microwave field, which can effectively inhibit the release of volatile matter in the lignite while effectively drying the lignite, and greatly reduce the hidden danger of fire during microwave drying of the lignite.
Description
Technical Field
The invention belongs to the technical field of coal drying, relates to a drying method for lignite, and particularly relates to a method for drying lignite by using a microwave process.
Background
With the large consumption of high-quality coal resources in China, the utilization of low-rank coal is more and more emphasized. The lignite resources in China are abundant, but because the lignite has high water content and low combustion or gasification efficiency, the large-scale application of the lignite is limited.
At present, when lignite is industrially utilized for liquefaction, dry distillation or gasification, drying and upgrading pretreatment are needed to reduce the moisture in the lignite to be below 10%.
The drying mode of the lignite mainly comprises drum drying, fluidized bed drying, microwave drying, hydrothermal dehydration and the like. The drum drying technology is relatively mature and widely applied, but the maintenance cost is higher and the drying efficiency is lower. Fluidized bed drying has high thermal efficiency, but high pressure drop and severe equipment wear. The hydrothermal dehydration requires large pressure, the operation cost is high, the wastewater is difficult to treat, and the continuous production is not easy to realize.
As a new drying mode, the microwave drying has the advantages of high drying speed, good selectivity, quick start and stop and little environmental pollution. In the microwave drying process, the temperature gradient of the material is reduced from inside to outside in sequence, and the heat transfer and water migration directions are from inside to outside. The drying method is different from the traditional drying method in that the heat transfer is from outside to inside and the moisture migration is from inside to outside, and is beneficial to the diffusion of the moisture and the improvement of the drying efficiency.
However, microwave drying mainly adopts a single radiation mode and a special heat transfer mode thereof, so that the temperature of heated lignite is gathered at the center of a coal sample, lignite reacts violently in the drying process, volatile components in the coal sample are released in a large quantity, and fire hazard is caused.
Therefore, the reasonable microwave drying process is designed, so that the drying efficiency of the lignite is ensured, the release of volatile matters in the lignite is effectively inhibited, the fire hazard is reduced, and the method has important significance for the industrial application of the lignite.
Disclosure of Invention
The invention aims to provide a lignite microwave drying process, which can effectively dry lignite, inhibit the release of volatile matters in the lignite and prevent fire from being caused in the drying process.
The following provides specific operation steps of the lignite microwave drying process.
1) The lignite is crushed into lignite particles of not more than 10 mm.
2) Controlling the water content of the lignite particles to be 40-60 wt%, and carrying out spraying humidification treatment on the lignite particles with insufficient water content to regulate the water content to be 40-60 wt%.
3) Respectively installing microwave generating devices on two side walls of the primary microwave drying chamber, setting the microwave incidence angle of the microwave generating devices to be 60-80 degrees, and sending the lignite particles meeting the water content requirement into the primary microwave drying chamber for primary microwave drying to reduce the water content of the lignite particles to 20-30 wt%.
4) Microwave generating devices are respectively arranged on two side walls of the second-stage microwave drying chamber, the microwave incidence angle of the microwave generating devices is 40-60 degrees, and the lignite particles subjected to primary microwave drying are sent into the second-stage microwave drying chamber for secondary microwave drying, so that the water content of the lignite particles is reduced to below 10 wt%.
The microwave incidence angle is an included angle between the axis of the transmitting opening of the microwave generating device and the horizontal plane.
And (3) sending the lignite particles treated by the drying process out of a two-section microwave drying chamber, and cooling to room temperature to obtain the dried lignite meeting the requirements.
In the lignite microwave drying process, the microwave radiation frequency of the primary microwave drying is preferably set to be 2.45GHz, and the microwave power is 600-1000W; the microwave radiation frequency of the two-stage microwave drying is 2.45GHz, and the microwave power is 500-800W.
Furthermore, the lignite particles are conveyed by a screw feeder and respectively enter a primary section microwave drying chamber and a secondary section microwave drying chamber.
Wherein the material stacking thickness of the lignite particles fed into the primary section and the secondary section microwave drying chamber is preferably 20-70 mm.
Furthermore, after the lignite particles with insufficient water content are subjected to spray humidification treatment, the spray humidified lignite particles are preferably kept still for not less than 2 hours and then are sent into a primary microwave drying chamber for drying.
The water in the lignite particles can be evaporated in the microwave drying process in the primary section and the secondary section microwave drying chambers to generate water vapor. The invention can also collect the generated water vapor and then enter the primary microwave drying chamber again, on one hand, the water vapor can preheat the lignite particles entering the primary microwave drying chamber, and on the other hand, the water vapor is used for maintaining a certain humidity in the primary microwave drying chamber, so that the water in the lignite particles is prevented from being evaporated too fast or excessively in the primary microwave drying chamber.
More specifically, in the primary microwave drying process, the temperature in the primary microwave drying chamber is preferably controlled to be 150-200 ℃.
And further, controlling the drying time of the lignite particles in the primary microwave drying chamber to be 3-8 min.
More specifically, in the two-stage microwave drying process, the temperature in the two-stage microwave drying chamber is preferably controlled to be 100-150 ℃.
And further, controlling the drying time of the lignite particles in the two-stage microwave drying chamber to be 10-20 min.
After spraying and humidifying, the surface moisture of the lignite particles is increased, the clearance of the lignite particles is increased, the stacking density is reduced, the internal temperature of the lignite particles is not easy to accumulate, and the drying process is smooth. The two-stage microwave drying is adopted, wherein the microwave radiation angle in the primary microwave drying chamber is larger, the absorption efficiency of lignite particles on microwaves is highest, the temperature rise is faster, and the moisture on the surfaces of the lignite particles and in macropores can be quickly removed; the microwave radiation angle in the second-stage microwave drying chamber is small, the absorption efficiency of the lignite particles to microwaves is low, the temperature rise is mild, and at the moment, the multi-layer adsorbed water and the single-layer adsorbed water combined with the oxygen-containing groups in the lignite particles are removed. The method for removing the water in the lignite particles in a grading manner in the microwave field effectively inhibits the release of volatile matters and greatly reduces the fire hazard when the lignite is dried by microwave.
According to the invention, the lignite is firstly sprayed and humidified to a certain degree to adjust the water content, and then a sectional type microwave drying mode is adopted, so that the good lignite drying efficiency is ensured, the release of volatile components in the lignite in the drying process is effectively inhibited, and the fire caused by overhigh local temperature of the lignite in the drying process is prevented through a reasonable and simple process. The process also effectively reduces the energy consumption of microwave drying, and achieves the purposes of energy conservation and emission reduction.
Detailed Description
The following examples are only preferred embodiments of the present invention and are not intended to limit the present invention in any way. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Example 1.
The embodiment selects the typical lignite in China, the water content of the typical lignite is about 30 percent, and the dry ash-free base volatile content of the typical lignite is about 45 percent. Crushing the lignite into lignite particles smaller than 10mm, spraying and humidifying, and adjusting the water content of the lignite to 41.50%.
And standing the humidified lignite particles for 2.5 hours, feeding the humidified lignite particles into a primary microwave drying chamber through a screw feeder, and slowly passing through the primary microwave drying chamber by using the material accumulation thickness of 40-50 mm, wherein the passing time, namely the drying time, is controlled to be 7 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to 70 degrees, setting the microwave radiation frequency of the microwave generating devices to 2.45GHz and the microwave power of 700W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. After primary microwave drying, the water content in the lignite particles is reduced to 25.69%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on two side walls of the secondary microwave drying chamber is adjusted to be 60 degrees, the microwave radiation frequency of the microwave generating device is set to be 2.45GHz, the microwave power is 500W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the lignite particles stay in the secondary microwave drying chamber for drying for 20min, and the final water content of the lignite particles is reduced to 9.81 percent after the lignite particles are dried by microwave radiation.
And (4) allowing the dried lignite particles to enter a discharging chamber and cooling to room temperature to obtain the dried lignite.
The water vapor generated in the drying process returns to the primary microwave drying chamber, and the humidifying effect is achieved on the basis of preheating the lignite particles.
The detection shows that the dried ash-free base volatile content of the lignite is 41.93 percent.
Comparative example 1.
Lignite particles smaller than 10mm in example 1 are fed into a primary microwave drying chamber through a screw feeder, and slowly pass through the primary microwave drying chamber with the material accumulation thickness of 40-50 mm, wherein the passing time, namely the drying time, is controlled to be 7 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to 70 degrees, setting the microwave radiation frequency of the microwave generating devices to 2.45GHz and the microwave power of 700W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. The water content in the lignite granules after primary microwave drying is reduced to 16.08%.
Under the condition, in the process of removing the moisture in the lignite, along with the release of volatile components, the local temperature of the lignite particles is detected to be rapidly increased to be more than 300 ℃, and meanwhile, more obvious blue smoke is emitted. Finally, the dried ashless-based volatile content of the lignite after drying is detected to be 19.21%, and more than 25% of volatile components are released.
Example 2.
The lignite of the embodiment has a moisture content of about 18% and a dry ash-free volatile content of about 45%. Crushing the lignite into lignite particles with the particle size of 10mm or less, spraying and humidifying the lignite particles, and adjusting the water content of the lignite to be 42.68%.
After standing for 3 hours, sending the humidified lignite particles into a primary microwave drying chamber through a screw feeder, slowly passing through the primary microwave drying chamber by the material accumulation thickness of 30-40 mm, and controlling the passing time, namely the drying time to be 7.5 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to 65 degrees, setting the microwave radiation frequency to 2.45GHz and the microwave power to 750W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. After primary microwave drying, the water content in the lignite particles is reduced to 22.52%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on two side walls of the secondary microwave drying chamber is adjusted to be 50 degrees, the microwave radiation frequency of the microwave generating device is set to be 2.45GHz, the microwave power is 700W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the lignite particles stay in the secondary microwave drying chamber for drying for 12min, and the water content is finally reduced to 7.58% after the lignite particles are subjected to microwave radiation drying.
And (4) allowing the dried lignite particles to enter a discharging chamber and cooling to room temperature to obtain the dried lignite.
The water vapor generated in the drying process returns to the primary microwave drying chamber, and the humidifying effect is achieved on the basis of preheating the lignite particles.
Through detection, the dried ash-free base volatile content of the lignite is 40.11%.
Comparative example 2.
The lignite particles of example 2, which were pulverized into particles of 10mm or less, were sprayed and humidified to adjust the water content of the lignite to 42.68%.
After standing for 3 hours, sending the humidified lignite particles into a primary microwave drying chamber through a screw feeder, slowly passing through the primary microwave drying chamber by the material accumulation thickness of 30-40 mm, and controlling the passing time, namely the drying time to be 7.5 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to 90 degrees, setting the microwave radiation frequency to 2.45GHz and the microwave power to 750W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. After primary microwave drying, the water content in the lignite particles is reduced to 19.89%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on two side walls of the secondary microwave drying chamber is adjusted to be 80 degrees, the microwave radiation frequency of the microwave generating device is set to be 2.45GHz, the microwave power is 700W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the lignite particles stay in the secondary microwave drying chamber for drying for 12min, and the water content is finally reduced to 4.91 percent after the lignite particles are subjected to microwave radiation drying.
Under the condition, in the process of removing the moisture in the lignite, along with the release of volatile components, the local temperature of the lignite particles is detected to be rapidly increased to be more than 300 ℃, and meanwhile, more obvious blue smoke is emitted. Finally, the dried ashless-based volatile content of the lignite after drying is detected to be 24.33%, and more than 20% of volatile components are released.
Comparative example 3.
The lignite particles of example 2, which were pulverized into particles of 10mm or less, were sprayed and humidified to adjust the water content of the lignite to 42.68%.
After standing for 3 hours, sending the humidified lignite particles into a primary microwave drying chamber through a screw feeder, slowly passing through the primary microwave drying chamber by the material accumulation thickness of 30-40 mm, and controlling the passing time, namely the drying time to be 7.5 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to be 50 degrees, setting the microwave radiation frequency to be 2.45GHz and the microwave power to be 750W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. The water content in the lignite granules after primary microwave drying is reduced to 27.25%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on two side walls of the secondary microwave drying chamber is adjusted to be 30 degrees, the microwave radiation frequency is set to be 2.45GHz, the microwave power is 700W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the lignite particles stay in the secondary microwave drying chamber for drying for 12min, and the water content is finally reduced to 15.83 percent after the lignite particles are subjected to microwave radiation drying.
The detection shows that the dried ash-free base volatile content of the lignite is 43.59 percent after drying.
Under this condition, the moisture removal from the lignite particles is incomplete.
Example 3.
The lignite of the embodiment has a water content of about 50% and a dry ash-free volatile content of about 60%. The lignite is crushed into lignite particles of 10mm or less without being sprayed and humidified.
And (3) feeding the crushed lignite particles into a primary microwave drying chamber through a spiral feeder, slowly passing through the primary microwave drying chamber by the material accumulation thickness of 30-40 mm, and controlling the passing time, namely the drying time, to be 4 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to be 75 degrees, setting the microwave radiation frequency to be 2.45GHz and the microwave power to be 900W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. After the primary microwave drying, the water content in the lignite particles was reduced to 28.14%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on the two side walls of the secondary microwave drying chamber is adjusted to be 60 degrees, the microwave radiation frequency of the microwave generating device is set to be 2.45GHz, the microwave power is 600W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the residence drying time of the lignite particles in the secondary microwave drying chamber is 15min, and the water content is finally reduced to 8.26 percent after the lignite particles are subjected to microwave radiation drying.
And (4) allowing the dried lignite particles to enter a discharging chamber and cooling to room temperature to obtain the dried lignite.
The water vapor generated in the drying process returns to the primary microwave drying chamber, and the humidifying effect is achieved on the basis of preheating the lignite particles.
Through detection, the dried ashless-based volatile content of the dried lignite is 53.62%.
Comparative example 4.
The lignite particles crushed into particles of 10mm or less in example 3 are fed into a primary microwave drying chamber through a screw feeder, and slowly pass through the primary microwave drying chamber with the material stacking thickness of 30-40 mm, wherein the passing time, namely the drying time, is controlled to be 4 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to be 75 degrees, setting the microwave radiation frequency to be 2.45GHz and the microwave power to be 550W, performing microwave irradiation drying on the lignite particles passing slowly, and controlling the temperature in the primary microwave drying chamber to be 155-165 ℃. After primary microwave drying, the water content in the lignite particles is reduced to 32.59%.
The lignite particles dried by the primary microwave enter a secondary microwave drying chamber, the incident angle of a microwave generating device on two side walls of the secondary microwave drying chamber is adjusted to be 60 degrees, the microwave radiation frequency is set to be 2.45GHz, the microwave power is 400W, the temperature in the secondary microwave drying chamber is controlled to be 120-130 ℃, the lignite particles stay in the secondary microwave drying chamber for drying for 15min, and the water content is finally reduced to 17.63% after the lignite particles are subjected to microwave radiation drying.
Through detection, the dried ashless-based volatile content of the dried lignite is 55.40%.
Under the condition, the moisture in the brown coal is not completely removed.
Comparative example 5.
The lignite particles crushed into particles of 10mm or less in example 3 are fed into a primary microwave drying chamber through a screw feeder, and slowly pass through the primary microwave drying chamber with the material stacking thickness of 30-40 mm, wherein the passing time, namely the drying time, is controlled to be 12 min. And respectively arranging microwave generating devices on two side walls of the primary microwave drying chamber, adjusting the incident angle of the microwave generating devices to 90 degrees, setting the microwave radiation frequency to 2.45GHz and the microwave power to 900W, controlling the temperature in the primary microwave drying chamber to be 155-165 ℃, and performing microwave irradiation drying on the lignite particles passing slowly.
Blue smoke is continuously emitted in the drying process. After drying, the water content of the lignite particles is reduced to 14.15% through detection, and partial water still remains and the drying requirement is not met. Further, it was examined that the dried ashless volatile matter content of the lignite was 42.09%, and about 18% of the volatile matter was released.
Claims (9)
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| US7666235B2 (en) * | 2005-11-30 | 2010-02-23 | Industrial Microwave Systems, L.L.C. | Microwave drying of coal |
| CN101504377A (en) * | 2009-02-28 | 2009-08-12 | 山东科技大学 | Microwave detection method and apparatus for moisture contained in coal on mine conveyer belt |
| CN102102939A (en) * | 2009-12-17 | 2011-06-22 | 金易通科技（北京）有限公司 | Coal microwave drying method |
| CN103788975B (en) * | 2014-01-22 | 2015-10-28 | 中国科学院上海高等研究院 | The method that brown coal microwave-heating utilizes |
| CN105219475B (en) * | 2015-10-28 | 2018-10-19 | 中国矿业大学 | Lignite upgrading system and its method for upgrading |
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