WO2016037379A1 - Method and apparatus for drying lignite and improving quality of lignite - Google Patents

Abstract

An apparatus for drying lignite and improving the quality of the lignite comprises an apparatus for generating a low-pressure superheated gas or steam, an air intake combined pipe (4), and a cylindrical heater (5). The cylindrical heater (5) is provided with a first material pusher (7), a feeding pipe (10), a discharging pipe (11), and more than one exhaust valve (6A, 6B, 6C). Wind closing apparatuses (9A, 9B) are disposed on the feeding pipe (10) and the discharging pipe (11). The discharging pipe (11) can be connected to a lignite rod shaping machine (12). The method for drying lignite and improving the quality of the lignite implemented by using the apparatus comprises the steps of: increasing, by means of a gas booster (1), the pressure of a gas in a gas storage tank (2) to above 0.1 MPa, and then heating to 105ºC to 400ºC by means of a heat exchanger (3); spraying a heated hot gas by sections into the cylindrical heater (5) to heat the lignite, and keeping the pressure in the cylindrical heater (5) above 0.1 MPa; opening the exhaust valves (6A, 6B, 6C) when the pressure in the cylindrical heater (5) is higher than that of the gas in the gas storage tank (2); and discharging the heated lignite from the discharging pipe (11). The mechanical hardness and thermal stability of the lignite dried by using the method and the apparatus are increased. The drying process is environmentally friendly, the water consumption is low and the device cost is low, so that the lignite is easily produced on a large scale.

Description

 Method and device for drying and upgrading brown coal Technical field

The invention relates to the field of processing and utilization of lignite, in particular to a device and a method for drying and processing lignite.

Background technique

As we all know, lignite is very large on the earth, but it has high water content, low unit heat value, easy self-ignition, easy powdering, low mechanical strength and thermal stability, which is not conducive to direct transportation and utilization. Over the years, countries around the world have done a lot of research on reducing lignite moisture, thereby increasing unit heat value and improving coal quality. However, there are still no mature technical processes and many drawbacks. Mainly: 1. High energy consumption, relying on a large amount of coal to evaporate a large amount of water in raw coal; 2. Environmentally friendly carbon emissions are large and polluting; 3. Finished powder is severe, mechanical strength and thermal stability are lower than that of raw coal. It is not conducive to transportation; 4, the equipment is complex, the cost is high, the production cost is high, and it is difficult to use in large-scale industrialization.

Summary of the invention

In view of the problems existing in the prior art, the present invention provides a method and apparatus for drying and upgrading lignite. The brown coal moisture after drying by the method and the device is significantly reduced, the unit heat value is increased, the particle volume is reduced, the water absorption is less, the mechanical hardness and thermal stability are increased, and the powdering and weathering are greatly reduced. Most of the vaporization heat of the water in the drying process is recycled, the energy consumption is low, the equipment cost is low, the production cost is low, the environmental protection is easy to control, and it is easy to mass-produce.

To achieve the above object, the technical solution of the present invention is:

A device for dry upgrading of lignite comprising: means for generating low pressure superheated steam or generating low pressure superheated gas, and a cylindrical heater connected to the apparatus; said means for generating low pressure superheated steam comprising a boiler, said generating low pressure The device for superheating gas comprises a gas booster, a gas storage tank and a heat exchanger connected in sequence, and the cylindrical heater is connected to the boiler or the heat exchanger through a set of intake air combination tubes; a first material pusher is disposed, and the cylindrical heater is provided with a feed pipe, a discharge pipe and one or more exhaust valves, and a wind shutoff device is arranged on the feed pipe and the drop pipe; The air intake combined tube includes a plurality of spaced apart branch pipes connected to the body of the cylindrical heater.

A lignite drying and upgrading device as described above, further comprising a coal bar forming machine having a feeding end connecting the blanking tube on the cylindrical heater, and a taper a discharge end, the narrow mouth of the tapered discharge end is a discharge port; A second material pusher is disposed in the coal rod forming machine.

The apparatus for drying and upgrading lignite as described above, wherein the intake manifold further comprises a manifold connecting a plurality of branch pipes, wherein the manifold is connected to the heat exchanger through an intermediate pipe, and the distance between the adjacent branches is 10 cm. -30cm .

a device for drying and upgrading lignite as described above, wherein the exhaust valve is disposed on a body of the cylindrical heater, It is also placed on the blanking tube of the cylindrical heater.

A method for drying and upgrading brown coal, which comprises the steps of: injecting an incoming low-pressure superheated gas or low-pressure superheated steam into a cylindrical heater to heat the lignite injected into the cylindrical heater, the entering The pressure of the low-pressure superheated gas or the low-pressure superheated steam is between 0.1 MPa and above, and the temperature is between 105 ° C and 400 ° C; the pressure in the cylindrical heater is maintained at 0.1 MPa or more, and the cylindrical heater is provided with The exhaust valve is opened when the pressure in the cylindrical heater is greater than the pressure of the incoming low pressure superheated gas or low pressure superheated steam; the heated lignite is discharged from the cylindrical heater. The lignite discharged from the cylindrical heater is used to accelerate the evaporation of water to obtain a finished product; or the lignite discharged from the cylindrical heater enters a coal rod forming machine and is tapped by a coal rod forming machine The end is extruded to form a coal rod to produce a finished product.

The above technical solutions are beneficial in that:

First, energy saving. The invention adopts a cylindrical heater with a propeller, and pressurizes the cylindrical heater through a boiler, or a gas storage tank and a heat exchanger, so that lignite naturally evaporates most of the water after processing, and the processing cost is consumed. The energy can be low and the unit heat value of lignite is increased.

Second, improve the scope of application. The lignite raw coal has poor strength and is easily weathered and powdered. Other normal or negative pressure dry lignite powder has a very high powdering rate, basically no mechanical strength and thermal stability, and the product can only be used as a low-grade fuel. However, the present invention controls the pressure and temperature in the cylindrical heater through the exhaust valve and the air closing device, and the mechanical strength and thermal stability of the lignite can reach more than 70%. In addition to the fuel, it can be used as a steam, coal chemical industry. Raw coal in other fields.

Third, the invention has the advantages of simple process, safe production, low equipment cost, low production cost, and easy large-scale industrial production and promotion.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

Figure 1 is a schematic view of the structure of the lignite drying and upgrading apparatus of the present invention (providing low pressure superheated gas);

2 is a schematic structural view 2 of the apparatus for drying and upgrading brown coal according to the present invention (providing low-pressure superheated steam).

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in order to make the present invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

A lignite dry upgrading device as shown in FIG. 1 includes a device for generating low pressure superheated steam or generating low pressure superheated gas, a set of intake manifold 4 and a cylindrical heater 5, and may further include a coal rod Forming machine 12.

The apparatus for generating low-pressure superheated gas includes a gas booster 1, a gas storage tank 2, and a heat exchanger 3 which are sequentially connected, and the cylindrical heater 5 is connected to the heat exchanger 3 through the intake manifold 4. The gas booster 1 can be generally referred to as an air compressor or a gas booster pump, and the heat exchanger 3 can be a device that can heat the gas and has a certain pressure resistance performance, such as coal burning, steam combustion, and electric heating.

As shown in Fig. 2, the apparatus for generating low-pressure superheated steam includes a boiler 17, and the cylindrical heater 5 is connected to the boiler 17 through an intake manifold.

As shown in FIGS. 1 and 2, the cylindrical heater 5 is a cylindrical container having a certain withstand voltage. A first material propeller 7 driven by the first motor 8 is disposed therein, and the first material propeller 7 may be a auger type auger or a vane type auger. The cylindrical heater 5 is provided with a feed pipe 10, a discharge pipe 11, and one or more exhaust valves, and the exhaust valve may be disposed only on the body of the cylindrical heater 5, or It is disposed on the drop tube 11 of the cylindrical heater 5. In the present embodiment, the body of the cylindrical heater 5 is provided with two exhaust valves 6A, 6B. The discharge pipe 11 of the cylindrical heater 5 is simultaneously provided with an exhaust valve 6C for setting the pressure value in the cylindrical heater 5 as needed, and automatically opening the exhaust gas under an overpressure condition. The feeding tube 10 and the blanking tube 11 of the cylindrical heater 5 are respectively provided with first and second closing devices 9A, 9B, and the first and second closing devices 9A, 9B can be closed. The device can prevent the airflow from escaping when the material passes, thereby ensuring a positive pressure environment inside the cylinder heater 5.

The intake air combination pipe 4 includes a plurality of spaced apart branch pipes 4A for connecting the body of the cylindrical heater 5 and a main pipe 4B, and the main pipe 4B is connected to heat exchange through an intermediate pipe 4C. Device 3. The branch pipe 4A, the main pipe 4B, and the intermediate pipe 4C are all pipes having a certain pressure resistance. The distance between adjacent branch pipes 4A of the present invention is set to be 10 cm to 30 cm to balance and save the amount of gas or steam injected.

If the raw coal to be processed is mainly pulverized coal having a particle diameter of less than 6 mm, a coal bar forming machine 12 having a feed pipe 11 connected to the cylindrical heater 5 may be added. The material end, and a tapered discharge end 13, the narrow mouth portion of the tapered discharge end 13 which is reduced in diameter from the inside to the outside is the discharge port 14. The coal bar forming machine 12 is provided with a second material pusher 16 driven by a second motor 15, which is a auger type auger.

 The method for drying and upgrading the lignite of the present invention by using the above-mentioned lignite drying and upgrading device is as follows:

In the first step, the gas (air, carbon dioxide, or the like which can be used as a non-fuel gas for heat conduction) in the gas storage tank 2 is pressurized by the gas booster 1 to 0.1 MPa or more, preferably 0.3 MPa to 0.5 MPa. When the gas pressure is higher, the thermal stability of the lignite processed by the subsequent process is better, but the process requirements and cost of the equipment are higher.

In the second step, the pressurized gas is heated by the heat exchanger 3 to 105 ° C to 400 ° C, preferably 150 ° C to 250 ° C to generate a low pressure superheated gas. Because lignite is heated by hot air above 105 °C, a series of chemical reactions begin to occur. The reaction between 150 °C and 250 °C is relatively fast and complete. When it exceeds 250 °C, a small amount of volatiles will escape the polluted tail gas, and when it exceeds 400 °C. Some lignites are too long in the heating chamber, and may be ignited due to the loss of most of the water, and the safety is lowered.

The low-pressure superheated gas generated in the above steps 1 and 2 can also be replaced by low-pressure superheated steam, which can be generated by the pressure heating of the boiler 17, and the generated low-pressure superheated steam should be pressurized to 0.1 MPa or more, preferably 0.3. Between MPa and 0.5 MPa, the temperature is raised to between 105 ° C and 400 ° C, preferably between 150 ° C and 250 ° C.

Step 3, the hot air heated by the heat exchanger 3 or the low-pressure superheated steam generated by the boiler 17 is sprayed into the body of the cylindrical heater 5 through a plurality of branch pipes 4A to heat the input into the cylindrical heater 5 Lignite inside. The raw coal enters the cylindrical heater 5 from the feed pipe 10, and the pressure of the cylindrical heater 5 is maintained at 0.1 MPa or more, preferably 0.3-0.5 MPa, and is advanced by the first material pusher 7 while being subjected to Heating of the hot air and hot steam entering the intake manifold 4. The heated lignite directly evaporates part of the water from the surface and the inside, and simultaneously produces a series of changes in the nature of the positive pressure environment, resulting in tight molecular structure, reduced volume, increased mechanical strength and thermal stability, hydrophilicity, The oxophilicity is reduced and a portion of the heat and carbon dioxide are released, which indirectly evaporates a portion of the moisture in the lignite. Lignite starts to react at 105 ° C, and the pressure is stronger than 0.1 MPa. The higher the temperature in the range of 105 ° C - 250 ° C, the faster the reaction, and the excess of 250 ° C will cause the volatiles to escape and convert to dry distillation. The greater the pressure applied to the reaction, the more complete the reaction, the better the effect, but the higher the requirements for the cylindrical heater 5, the first material pusher and the first and second door closers 9A, 9B, the higher the cost. . Due to the certain positive pressure maintained in the cylindrical heater 5, the direct evaporation and indirect evaporation of the lignite mostly condense, and the heat of vaporization is released on the surface of the coal particles to increase the temperature of the lignite itself and the cylinder heater 5 cylinders. The temperature in the body.

The pressure set in the cylindrical heater 5 should be maintained at 0.1 MPa or more, preferably between 0.3 MPa and 0.5 MPa. However, due to the intake of the intake manifold 4 and a portion of the steam and carbon dioxide generated by the lignite, the pressure in the cylindrical heater 5 is increased, and when the pressure set in the cylindrical heater 5 is exceeded, three The exhaust valves 6A, 6B, and 6C disposed on the cylindrical heater 5 are automatically opened for exhausting, and the exhausted gas is a low-temperature gas, and the temperature is lower than 100 ° C, and a large amount of condensation is carried out, and is atomized by a positive pressure. Moisture, and then discharge the gas to the next step of environmental protection.

Step 4: If the raw coal to be processed is mainly lump coal having a large particle size, after the heated lignite is discharged from the blanking pipe 11 of the cylindrical heater 5, most of the water condensed on the surface of the lignite particles will naturally evaporate. And use the fan to blow air, strengthen the air flow on the surface of lignite, can accelerate the evaporation of water, until the coal temperature is reduced, it is the finished product.

If the raw coal to be processed is mainly pulverized coal having a particle diameter of less than 6 mm, the heated lignite is discharged from the blanking pipe 11 of the cylindrical heater 5, and then enters the coal bar forming machine 12, and is advanced by the second pusher 16. To the tapered discharge end 13, the diameter of the discharge port 14 of the discharge end 13 is reduced, and the pulverized coal is extruded to form a coal rod which is discharged through the discharge port 14. The condensed water on the surface of the pulverized coal is used as a lubricant for extrusion molding. The change in the yield and strength can be adjusted by changing the length and compression ratio of the discharge end 13, and the prepared coal rod will naturally evaporate most of the water after being cooled. At the same time, the strength is increased and the powder is substantially eliminated.

The above description shows and describes a preferred embodiment of the present invention. As described above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be construed as being Combinations, modifications, and environments are possible, and can be modified by the teachings of the above teachings or related art within the scope of the inventive concept described herein. All changes and modifications made by those skilled in the art are intended to be within the scope of the appended claims.

Claims (10)

A device for dry upgrading of lignite, characterized by comprising: a device for generating low-pressure superheated steam or generating low-pressure superheated gas, and a cylindrical heater connected to the device; the device for generating low-pressure superheated steam includes a boiler, The device for generating low-pressure superheated gas comprises a gas booster, a gas storage tank and a heat exchanger connected in sequence, and the cylindrical heater is connected to the boiler or the heat exchanger through a set of intake air combination tubes; the cylinder a first material pusher is arranged in the heater, and the cylindrical heater is provided with a feed pipe, a discharge pipe and one or more exhaust valves, and is arranged on the feed pipe and the drop pipe The air intake assembly includes a plurality of spaced apart branch pipes connected to the body of the cylindrical heater. A lignite drying and upgrading apparatus according to claim 1, further comprising a coal bar forming machine having a feeding end for connecting a blanking tube on the cylindrical heater. And a tapered discharge end, the narrow mouth of the tapered discharge end is a discharge port; A second material pusher is disposed in the coal rod forming machine. The apparatus for drying and upgrading lignite according to claim 1 or 2, wherein the intake manifold further comprises a manifold connecting a plurality of branch pipes, wherein the manifold is connected to the heat exchanger through an intermediate pipe, and The distance between adjacent branches is 10cm-30cm . The apparatus for dry-cleaning lignite according to claim 1 or 2, wherein the exhaust valve is disposed on the body of the cylindrical heater, It is also placed on the blanking tube of the cylindrical heater. A method for dry upgrading of lignite, characterized in that: the step of spraying into the cylindrical heater is to inject the incoming low-pressure superheated gas or low-pressure superheated steam to heat the brown coal into the cylindrical heater. The pressure of the incoming low-pressure superheated gas or low-pressure superheated steam is above 0.1 MPa, and the temperature is between 105 ° C and 400 ° C; the pressure in the cylindrical heater is maintained above 0.1 MPa, and the cylindrical heater The exhaust valve provided is opened when the pressure in the cylindrical heater is greater than the pressure of the incoming low-pressure superheated gas or the low-pressure superheated steam; the heated lignite is discharged from the cylindrical heater. A method for dry upgrading of lignite according to claim 5, characterized in that the lignite discharged from the cylindrical heater is cooled by a fan to accelerate the evaporation of the water to obtain a finished product. A method for dry upgrading of lignite according to claim 5, characterized in that the lignite discharged from the cylindrical heater enters a coal bar forming machine and is extruded through a tapered discharge end of the coal bar forming machine. Coal rods, finished products. A method for dry upgrading of lignite according to claim 5, 6 or 7, characterized in that said incoming low pressure superheated gas or low pressure superheated steam is pressurized to 0.3MPa-0.5MPa, and heated to 150 ° C -250 ° C. A method of dry upgrading of lignite according to claim 5, 6 or 7, wherein the pressure in said cylindrical heater is maintained at 0.3-0.5 MPa. A method of dry upgrading of lignite according to claim 8, characterized in that the pressure in the cylindrical heater is maintained at 0.3-0.5 MPa.