A system and process for strengthening lignite dehydration by coupling steam explosion with chemical reforming

Abstract

The present invention relates to a system and process for strengthening lignite dehydration by coupling steam explosion with chemical modification, which belongs to the technical field of lignite or low-rank coal quality improvement, and solves the problems of high energy consumption and low efficiency of lignite drying and dehydration technology in the prior art, and the products are prone to spontaneous combustion. The present invention includes a chemical modification unit and a steam explosion dehydration unit, wherein the chemical modification unit pre-crushes, chemically modifies and mechanically dehydrates the lignite; the steam explosion dehydration unit performs steam explosion on the lignite product pretreated by the chemical modification unit to obtain a dehydrated product. The present invention chemically modifies lignite with the help of non-polar hydrocarbon oil, regulates the hydrophobicity of the lignite surface, reduces the coal-water interaction, thereby reducing the difficulty of removing water from the coal, and reducing the energy consumption of dehydration and drying; the capillary water in the lignite is effectively removed by steam explosion dehydration, and the production of lignite products with low moisture content is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of lignite or low-rank coal upgrading, and in particular to a system and process for enhancing lignite dehydration by coupling steam flash explosion with chemical modification. Background Art

[0002] With the development of my country's national economy and the upgrading of its industrial structure, the demand for coal resources in social production has increased day by day. With the consumption of high-quality coal deposits, my country's coal resources have become low-quality overall, and the proportion of low-rank coal in total coal resources has also increased day by day. Improving the quality of low-rank coal has become an urgent need in the industry. Lignite is an important type of low-rank coal. Its total global resources are about 4.35 trillion tons, accounting for 21% of the total global coal resources, and lignite in my country also accounts for about 13% of the total coal resources. Lignite is not only an important source of thermal coal for thermal power plants, but also an important chemical raw material, catalyst carrier, adsorbent, etc. However, the moisture content of lignite is usually as high as 30% to 60%. The extremely high moisture content seriously limits the extensiveness and economy of its quality improvement and utilization. The pre-drying and dehydration of lignite has become an important prerequisite and key link for its efficient and clean utilization.

[0003] The extremely high water content of lignite is due to the combined effect of its surface morphology and surface physical and chemical properties. On the one hand, the surface of lignite is rich in polar oxygen-containing functional groups, such as carboxyl and hydroxyl groups, which makes the surface of lignite extremely hydrophilic and easily bridges with water molecules through hydrogen bonds to form a dense hydration film, making it difficult to remove water. On the other hand, lignite has a rich pore structure. Under the action of pore capillary action and surface hydrophilic effect, a large amount of capillary water is easily stored in the pore structure of lignite. The combined effect of pore structure and hydrophilic surface leads to extremely high water content in lignite and difficulty in removing water.

[0004] Traditional mechanical extrusion or thermal drying has significant problems in dehydrating lignite, such as low efficiency and high energy consumption. For lignite with hydrophilic surface and well-developed internal pores, traditional mechanical extrusion dehydration methods and equipment are difficult to effectively remove moisture from lignite, while thermal drying dehydration technology requires heating the moisture in the coal from liquid to gas to remove it from the coal. This phase change process consumes a lot of energy, and the dried product has problems such as too high temperature, easy to be over-crushed under the thermal shock of the system, and easy to spontaneously combust. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a system and process for enhancing lignite dehydration by coupling steam flash explosion with chemical modification, so as to solve the problems of high energy consumption and low efficiency of existing lignite drying and dehydration technology, and easy spontaneous combustion of products.

[0006] On the one hand, the present invention provides a steam flash explosion coupled chemical modification enhanced lignite dehydration system, comprising a chemical modification unit and a steam flash explosion dehydration unit, wherein the chemical modification unit pre-crushes, chemically modifies and mechanically dehydrates the lignite; the steam flash explosion dehydration unit performs steam flash explosion on the lignite product pretreated by the chemical modification unit to obtain a dehydrated product.

[0007] Furthermore, the chemical modification unit comprises a high pressure roller mill, a relaxation screen and a pulp mixer.

[0008] Furthermore, the output end of the high-pressure roller mill is connected to the input end of the flap screen, and the output end on the screen of the flap screen is connected to the input end of the high-pressure roller mill.

[0009] Furthermore, the under-screen output end of the relaxation screen is connected to the input end of the pulp mixer.

[0010] Furthermore, the chemical modification unit also includes a plate and frame filter press, the output end of the pulping machine is connected to the input end of the plate and frame filter press, and the dehydrated product of the plate and frame filter press is used as a raw material for the steam flash explosion dehydration operation.

[0011] Furthermore, the steam explosion dehydration unit comprises a steam explosion dehydrator, and the output end of the plate and frame filter press is connected to the steam explosion dehydrator.

[0012] Furthermore, the steam flash explosion dehydration unit further comprises a steam generator and a steam heater, and the air outlet of the steam generator is communicated with the air inlet of the steam heater.

[0013] Furthermore, the steam flash explosion dehydrator is provided with an air inlet, and the air outlet of the steam heater is connected to the air inlet.

[0014] Furthermore, the steam flash explosion dehydration unit further includes a first air flow valve, which is arranged between the steam generator and the steam heater.

[0015] On the other hand, the present invention provides a process for strengthening lignite dehydration by coupling steam explosion with chemical modification, using the above-mentioned system for strengthening lignite dehydration by coupling steam explosion with chemical modification, the steps include:

[0016] Step S1: chemical modification;

[0017] Step S2: steam flash explosion dehydration.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] (1) The present invention firstly chemically modifies lignite with the aid of non-polar hydrocarbon oil, regulates the surface hydrophobicity of lignite, reduces the coal-water interaction, thereby reducing the difficulty of removing water from the coal and reducing the energy consumption of dehydration and drying; then, the capillary water in the lignite is effectively removed through steam flash dehydration technology, thereby realizing the production of lignite products with low moisture content.

[0020] (2) In the process of removing capillary water from lignite by steam flash explosion dehydration technology, the water in the coal is removed in liquid form at a high speed, and no phase change occurs during the removal process. The dehydration process has low energy consumption and high energy utilization rate.

[0021] (3) The lignite crushing of the present invention adopts a high-pressure roller mill-relaxation screen system, which replaces the traditional multi-stage crushing-grinding-screening operation, greatly simplifying the system process; the quasi-static pressure crushing characteristics of the high-pressure roller mill reduce the energy consumption of the crushing operation, and its characteristics of crushing the material layer also significantly reduce wear, greatly reducing the energy consumption of the crushing operation; the relaxation screen effectively reduces the energy consumption of the grading operation while improving the efficiency of the crushing product grading operation.

[0022] (4) The present invention uses a mixture of superheated steam and high-temperature nitrogen as the heating medium in the high-pressure bin of the steam flash explosion dehydrator, thereby creating a high-temperature and high-pressure environment required for the lignite stacking process in the high-pressure bin, reducing the amount of steam used, reducing the working intensity of the steam generator and reducing production costs.

[0023] (5) The present invention uses steam flash explosion (i.e., gas explosion technology) to dehydrate lignite through the dehydration process of a steam flash explosion dehydrator. The extremely high-speed pressure relief of the high-pressure chamber realizes the high-speed expulsion and removal of moisture (especially capillary water) in the lignite. The steam explosion is completed almost instantly (within 0.1 s). The explosion process is violent and efficient, and is an adiabatic expansion process, with small heat loss in the system.

[0024] (6) The final dried material temperature of the present invention is about 50°C, the product only takes away a small amount of sensible heat, the heat energy loss is small, and the overall energy utilization rate of the system is high; the surface of the lignite has been chemically modified during the compression process, and the temperature of the final dried product is low, and it is not easy to spontaneously combust.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 It is a structural schematic diagram of a steam flash explosion coupled chemical reforming enhanced lignite dehydration system according to a specific embodiment;

[0028] Figure 2 It is a structural schematic diagram of a steam flash explosion dehydrator of a specific embodiment;

[0029] Figure 3 The present invention is a flow chart of a process for enhancing lignite dehydration by coupling steam flash explosion with chemical reforming according to a specific embodiment.

[0030] Reference numerals:

[0031] 100-chemical modification unit; 101-high pressure roller mill; 102-relaxation screen; 103-slurry mixer; 104-plate and frame filter press;

[0032] 200-steam flash explosion dehydration unit; 201-steam flash explosion dehydration machine; 202-high pressure chamber; 203-gas explosion chamber; 204-first discharge port; 205-feed port; 206-protective housing; 207-shock absorber; 208-second discharge port; 209-steam generator; 210-steam heater; 211-air inlet; 212-first air flow valve; 213-nitrogen heater; 214-second air flow valve. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0034] Example 1

[0035] A specific embodiment of the present invention, as Figure 1 As shown, a steam flash explosion coupled chemical modification enhanced lignite dehydration system is disclosed, including a chemical modification unit 100 and a steam flash explosion dehydration unit 200. The chemical modification unit 100 is used for pre-crushing, chemical modification and mechanical dehydration of lignite, and pre-treating the lignite as is; the steam flash explosion dehydration unit 200 is used for steam flash explosion dehydration of the fine-grained lignite product after chemical modification to obtain a final dehydrated product.

[0036] Compared with the prior art, the steam flash explosion coupled chemical modification enhanced lignite dehydration system provided in this embodiment uses non-polar hydrocarbon oil to chemically modify lignite, regulates the hydrophobicity of the lignite surface, reduces coal-water interaction, thereby reducing the difficulty of removing water from the coal and reducing the energy consumption of dehydration and drying; the steam flash explosion dehydration technology is used to effectively remove capillary water in the lignite, and the production of lignite products with low moisture content is achieved. The steam explosion is completed almost instantly (within 0.1s), the explosion process is violent and efficient, and it is an adiabatic expansion process, and the system heat loss is small.

[0037] The chemical modification unit 100 includes a high-pressure roller mill 101, a relaxation screen 102, and a pulp mixer 103. The output end of the high-pressure roller mill 101 is connected to the input end of the relaxation screen 102, the upper screen output end of the relaxation screen 102 is connected to the input end of the high-pressure roller mill 101, and the lower screen output end of the relaxation screen 102 is connected to the input end of the pulp mixer 103.

[0038] The raw coal enters the high pressure roller mill 101 for ultra-fine crushing, and the ultra-fine crushed products of the high pressure roller mill 101 are fed into the relaxation screen 102 for classification. The finely crushed materials under the relaxation screen 102 are transported to the pulping machine 103 for pulping treatment to achieve chemical modification, and the coarse-grained materials on the relaxation screen 102 are returned to the high pressure roller mill 101 for further crushing.

[0039] The lignite crushing of this embodiment adopts high-pressure roller mill 101 for crushing and relaxation screen 102 for screening, which replaces the traditional multi-stage crushing and then screening operation, greatly simplifying the system process; the quasi-static pressure crushing characteristics of the high-pressure roller mill 101 reduce the energy consumption of the crushing operation, and its characteristic of crushing the material layer also significantly reduces wear and tear, greatly reducing the energy consumption of the crushing operation; the relaxation screen 102 effectively reduces the energy consumption of the grading operation while improving the efficiency of the crushing product grading operation.

[0040] Considering that the raw coal is output as a lignite slurry product after chemical modification by the pulping machine 103, and further mixed with water, which needs to be discharged, the chemical modification unit 100 also includes a plate-frame filter press 104. The output end of the pulping machine 103 is connected to the input end of the plate-frame filter press 104, and the lignite slurry product after chemical modification by the pulping machine 103 is sent to the plate-frame filter press 104 for filtration and dehydration. The dehydrated product of the plate-frame filter press 104 is used as the raw material for the steam flash explosion dehydration operation, and the filtrate of the plate-frame filter press 104 is fed back to the pulping machine 103.

[0041] Combination Figure 1 and Figure 2As shown, the steam explosion dehydration unit 200 includes a steam explosion dehydrator 201, and the steam explosion dehydrator 201 includes a high-pressure bin 202 and a gas explosion bin 203, the high-pressure bin 202 is arranged at the upper part of the gas explosion bin 203, and the lower part of the high-pressure bin 202 is located in the gas explosion bin 203, and the lower end of the high-pressure bin 202 is provided with a first discharge port 204, and the first discharge port 204 is located in the gas explosion bin 203, and the material discharged from the high-pressure bin 202 directly falls into the gas explosion bin 203 through the first discharge port 204. Preferably, the high-pressure bin 202 and the gas explosion bin 203 are arranged concentrically.

[0042] Considering that the dehydrated product of the plate and frame filter press 104 needs to be fed into the steam flash explosion dehydrator 201 for steam flash explosion dehydration, a feed port 205 is provided on the top of the high-pressure chamber 202 , and the output end of the plate and frame filter press 104 is connected to the feed port 205 .

[0043] Due to the instantaneous pressure difference in the steam flash explosion process, the single-layer shell structure has poor impact resistance, so a protective shell 206 is provided outside the high-pressure chamber 202. In order to reduce the heat, pressure and steam loss of the system, a gap is provided between the protective shell 206 and the high-pressure chamber 202, and the gap is filled with insulation material.

[0044] In this embodiment, a protective shell 206 is provided on the outside of the high-pressure chamber 202 to increase the stability of the structure. At the same time, filling insulation material between the protective shell 206 and the high-pressure chamber 202 can effectively reduce the heat and pressure loss of the system.

[0045] Taking into account the vibrations generated during the instantaneous depressurization process of steam explosion, in order to mitigate the adverse effects of the vibrations on the equipment and maintain long-term stable operation of the equipment, the steam explosion dehydration unit 200 also includes a shock absorber 207, which is arranged on a bracket below the high-pressure chamber 202.

[0046] In this embodiment, by arranging the shock absorber 207 on the bracket below the high-pressure chamber 202, the adverse effect of the vibration shock generated by the steam flash explosion overshoot on the equipment can be effectively mitigated.

[0047] In order to facilitate the discharge of the dehydrated product, the bottom of the gas explosion bin 203 is an inverted cone structure, and a second discharge port 208 is provided at the bottom of the inverted cone structure.

[0048] The steam flash explosion dehydration unit 200 further includes a steam generator 209 and a steam heater 210 . The gas outlet of the steam generator 209 is connected to the gas inlet of the steam heater 210 , and the gas outlet of the steam heater 210 is connected to the high-pressure chamber 202 .

[0049] It can be understood that in order to input saturated steam into the steam flash explosion dehydrator 201, an air inlet 211 is provided on the steam flash explosion dehydrator 201, one end of the air inlet 211 is connected to the air outlet of the steam heater 210, and the other end of the air inlet 211 passes through the protective shell 206 and the outer wall of the high-pressure chamber 202 to enter the interior of the high-pressure chamber 202.

[0050] In order to facilitate the control of the delivery of saturated steam, the steam flash explosion dehydration unit 200 further includes a first air flow valve 212 , which is disposed between the steam generator 209 and the steam heater 210 .

[0051] In order to reduce the working intensity of the steam generator 209 and reduce the production cost, the steam flash explosion dehydration unit 200 also includes a nitrogen heater 213, nitrogen is introduced into the air inlet of the nitrogen heater 213, and the air outlet of the nitrogen heater 213 is connected to the air inlet 211 of the steam flash explosion dehydration machine 201.

[0052] In this embodiment, a mixture of superheated steam and high-temperature nitrogen is used as the heating medium in the high-pressure bin of the steam flash explosion dehydrator, thereby creating a high-temperature and high-pressure environment required for the lignite stacking process in the high-pressure bin, reducing steam consumption, reducing the working intensity of the steam generator and reducing production costs.

[0053] It can be understood that in order to control the input amount of nitrogen, a second air flow valve 214 is provided upstream of the nitrogen heater 213 .

[0054] Furthermore, a high-pressure gas storage tank (not shown in the figure) can be added downstream of the steam heater 210. Under this structure, the gas outlets of the nitrogen heater 213 and the steam heater 210 are both connected to the high-pressure gas storage tank, and the gas outlet of the high-pressure gas storage tank is connected to the gas inlet 211.

[0055] Example 2

[0056] Another specific embodiment of the present invention, as Figure 3 As shown, a steam flash explosion coupled with chemical modification to enhance lignite dehydration process is disclosed, using the steam flash explosion coupled with chemical modification to enhance lignite dehydration system of Example 1, the steps include:

[0057] Step S1: Chemical modification.

[0058] Step S1.1: Add water and surfactant into the slurry mixer 103 and stir for 2 minutes.

[0059] Specifically, the water is tap water, the surfactant is non-polar hydrocarbon oil, and the dosage is 1 kg / t 干煤泥 .

[0060] Step S1.2: The raw coal is crushed and added into the slurry mixer 103 and stirred for 5 minutes.

[0061] Specifically, the high pressure roller mill 101 performs ultra-fine crushing on the lignite raw coal, and the ultra-fine crushed products of the high pressure roller mill 101 are fed into the fluff screen 102 for classification, and the fine-grained materials under the fluff screen 102 are transported to the pulp mixer 103 for pulping treatment to achieve chemical modification, and the coarse-grained materials on the fluff screen 102 are returned to the high pressure roller mill 101 for re-crushing. Preferably, the mesh diameter of the fluff screen 102 is 2 mm.

[0062] Step S1.3: the coal-water mixture discharged from the pulping machine 103 enters the plate-frame filter press 104 for filtration, and the dehydrated product of the plate-frame filter press 104 is fed into the high-pressure chamber 202 .

[0063] Specifically, the lignite slurry product after chemical modification by the slurry mixer 103 is sent to the plate and frame filter press 104 for filtration and dehydration. The dehydrated product of the plate and frame filter press 104 is the raw material for steam flash explosion dehydration operation, and the filtrate of the plate and frame filter press 104 is fed back to the slurry mixer 103.

[0064] The working pressure of the plate and frame filter press 104 is about 0.8 MPa, and the filtration time is about 2 minutes. After filtration, the moisture content of the lignite is reduced from about 50% to about 25%.

[0065] Step S2: steam flash explosion dehydration.

[0066] Step S2.1: feeding the heated saturated steam and nitrogen into the high pressure chamber 202.

[0067] Specifically, the steam generator 209 generates saturated steam, which is fed into the steam heater 210 through the first air flow valve 212 and the air flow rate is adjusted. The superheated saturated steam heated by the steam heater 210 is fed into the high-pressure chamber 202 of the steam flash explosion dehydrator 201. Nitrogen is fed into the nitrogen heater 213 through the second air flow valve 214 and the air flow rate is adjusted. After being heated by the nitrogen heater 213, it is fed into the high-pressure chamber 202 of the steam flash explosion dehydrator 201.

[0068] The steam generator 209 produces saturated steam with a flow rate of about 18m 3 / h, the superheated steam temperature heated by steam heater 210 is about 280℃, and the flow rate is 50m 3 / h; the temperature of high-temperature nitrogen after heating by nitrogen heater 213 is about 280℃, and the flow rate is 30m 3 / h or so.

[0069] Step S2.2: Maintain the pressure in the high pressure chamber 202 for 10 minutes.

[0070] Specifically, the lignite is pressurized in the high-pressure chamber 202 for 10 minutes, and the gas pressure in the high-pressure chamber 202 is maintained at about 3 MPa, and the pressure is provided by saturated steam and nitrogen.

[0071] Step S2.3: Open the first discharge port 204 of the high-pressure chamber 202 to perform steam flash explosion to obtain a dehydrated product.

[0072] Specifically, the first discharge port 204 of the high-pressure chamber 202 is opened, and the material (lignite) in the high-pressure chamber 202 is ejected into the gas explosion chamber 203 under high pressure for steam explosion dehydration, and the final dehydrated product is discharged through the second discharge port 208. The pressure relief time is within 0.1s, and the temperature of the discharged material is about 50°C.

[0073] Example 3

[0074] like Figure 1-Figure 3 As shown, this embodiment discloses a steam flash explosion coupled chemical modification enhanced lignite dehydration process, using the system of Example 1, and selecting Inner Mongolia Shengli lignite as the dehydration raw material with a moisture content of 28.18%.

[0075] The lignite is crushed to a particle size of less than 2 mm using a high pressure roller mill 101 and a relaxation screen 102 system.

[0076] The crushed lignite is slurried by a slurry mixer 103. During the slurry mixing process, the coal-water mass ratio is 1:10. The chemical modification uses non-polar hydrocarbon oil as a modifier, and the dosage is 1kg / t. 干煤泥 The slurry preparation time is 5 minutes. The coal slurry after chemical modification is fed into the plate and frame filter press 104 for mechanical extrusion and dehydration.

[0077] The working pressure of the plate and frame filter press 104 is 0.8 MPa, and the working time is 2 minutes. After filtration and dehydration, the moisture content of the lignite is reduced from about 50% to about 25%. The coal slime after filtration is added into the high-pressure chamber 202 through the feed port 205 of the steam flash explosion dehydrator 201.

[0078] Steam generator 209 produces a flow rate of 18m 3 / h of saturated steam, heated to 280°C by steam heater 210, with a flow rate of 50m 3 / h; nitrogen is heated to 280°C by nitrogen heater 213, with a flow rate of 30m 3 / h; high-temperature gas (nitrogen and steam) is introduced into the high-pressure chamber 202 from the air inlet 211 until the pressure of the high-pressure chamber 202 rises to 3MPa, then the introduction of high-temperature gas is stopped and the valves (the first air flow valve 212 and the second air flow valve 214) are closed; the pressure maintenance operation is carried out in the high-pressure chamber 202 for 10 minutes; after the pressure maintenance is completed, the explosion cylinder is automatically started (i.e., the first discharge port 204 is opened), and the material is ejected into the gas explosion chamber 203, and the ejection pressure relief time is controlled within 0.1s. At the moment of pressure relief, the high-pressure steam adiabatically expands and does work to high-speed drive and dehydrate the moisture in the lignite.

[0079] After steam flash explosion dehydration, the dry material is discharged from the second discharge port 208. The moisture content of the final dry product is about 4% (mass percentage) and the temperature is 50°C.

[0080] Example 4

[0081] like Figure 1-Figure 3 As shown, this embodiment discloses a steam flash explosion coupled chemical modification enhanced lignite dehydration process, using the system of Example 1, and selecting Inner Mongolia Baorixile lignite as the dehydration raw material with a moisture content of 27.35%.

[0082] The lignite is crushed to a particle size of less than 2 mm using a high pressure roller mill 101 and a relaxation screen 102.

[0083] The crushed lignite is slurried by a slurry mixer 103. During the slurry mixing process, the coal-water mass ratio is 1:10. The chemical modification uses non-polar hydrocarbon oil as a modifier, and the dosage is 1kg / t. 干煤泥 The slurry preparation time is 5 minutes. The coal slurry after chemical modification is fed into the plate and frame filter press 104 for mechanical extrusion and dehydration.

[0084] The working pressure of the plate and frame filter press 104 is 0.8 MPa, and the working time is 2 minutes. After filtration and dehydration, the moisture content of the lignite is reduced from about 50% to about 25%. After filtration, the coal slime is added into the high-pressure chamber 202 through the feed port 205 of the steam flash explosion dehydrator 201.

[0085] Steam generator 209 produces a flow rate of 18m 3 / h of saturated steam, heated to 280°C by steam heater 210, with a flow rate of 50m 3 / h; nitrogen is heated to 280°C by gas heater 213, with a flow rate of 30m 3 / h; high-temperature gas (nitrogen and steam) is introduced into the high-pressure chamber 202 from the air inlet 211 until the pressure in the high-pressure chamber 202 rises to 3MPa, then the introduction of high-temperature gas is stopped and the valves (the first air flow valve 212 and the second air flow valve 214) are closed; the pressure maintenance operation is carried out in the high-pressure chamber 202 for 10 minutes; after the pressure maintenance is completed, the explosion cylinder is automatically started (i.e., the first discharge port 204 is opened), and the material is ejected into the gas explosion chamber 203, and the ejection pressure relief time is controlled within 0.1s. At the moment of pressure relief, the high-pressure steam adiabatically expands and does work to high-speed drive and dehydrate the moisture in the lignite.

[0086] After steam flash explosion dehydration, the dry material is discharged from the second discharge port 208. The final lignite moisture content is about 9% (mass percentage) and the temperature is 62°C.

[0087] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A steam explosion coupled chemical reforming enhanced lignite dehydration system, characterized in that: It comprises a chemical modification unit (100) and a steam explosion dehydration unit (200), wherein the chemical modification unit (100) pre-crushes, chemically modifies and mechanically dehydrates the lignite; and the steam explosion dehydration unit (200) performs steam explosion on the lignite product pre-treated by the chemical modification unit (100) to obtain a dehydrated product. The chemical modification unit (100) comprises a high-pressure roller mill (101), a relaxation screen (102), a pulp mixer (103) and a plate-frame filter press (104); the output end of the high-pressure roller mill (101) is connected to the input end of the relaxation screen (102); the upper screen output end of the relaxation screen (102) is connected to the input end of the high-pressure roller mill (101); the lower screen output end of the relaxation screen (102) is connected to the input end of the pulp mixer (103); the output end of the pulp mixer (103) is connected to the input end of the plate-frame filter press (104); the dehydrated product of the plate-frame filter press (104) is used as a raw material for a steam flash explosion dehydration operation; the steam flash explosion dehydration unit (200) comprises a steam flash explosion dehydrator (201); and the output end of the plate-frame filter press (104) is connected to the steam flash explosion dehydrator (201); The steam flash explosion dehydrator (201) comprises a high-pressure chamber (202) and a gas explosion chamber (203), wherein the high-pressure chamber (202) is arranged at the upper part of the gas explosion chamber (203), and the lower part of the high-pressure chamber (202) is located in the gas explosion chamber (203), a protective shell (206) is arranged on the outer side of the high-pressure chamber (202), a gap is arranged between the protective shell (206) and the high-pressure chamber (202), and the gap is filled with a heat-insulating material; The steam explosion dehydration unit (200) further comprises a steam generator (209), a steam heater (210) and a nitrogen heater (213); nitrogen is introduced into an air inlet of the nitrogen heater (213); an air outlet of the nitrogen heater (213) is in communication with an air inlet (211) of the steam explosion dehydration machine (201); an air outlet of the steam generator (209) is in communication with an air inlet of the steam heater (210); and an air outlet of the steam heater (210) is in communication with the air inlet (211).

2. The steam explosion coupled chemical reforming and strengthening lignite dehydration system according to claim 1 is characterized in that: The steam flash explosion dehydration unit (200) further comprises a first air flow valve (212), wherein the first air flow valve (212) is arranged between the steam generator (209) and the steam heater (210).

3. A process for strengthening lignite dehydration by coupling steam explosion with chemical modification, characterized in that: The steam flash explosion coupled chemical reforming enhanced lignite dehydration system according to any one of claims 1 to 2 comprises the following steps: Step S1: chemical modification; Step S2: steam flash explosion dehydration.

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