System for indirectly drying lignite through low-pressure steam

Abstract

The utility model belongs to the technical field of electric power chemical equipment, and particularly relates to a low-pressure steam indirect lignite drying system which comprises a crusher, a raw coal bunker, a coal feeder, a dryer, a screw conveyer, a first rotary discharge valve, a first embedded scraper conveyer, a condensation tank, a dust remover and an induced draft fan. The crusher is connected with a raw coal bunker, the raw coal bunker is connected with a coal feeder, and the coal feeder is connected with a particle bin of the dryer; a particle outlet of the drying machine is connected with a spiral conveyer, the spiral conveyer is connected with a first embedded scraper conveyer through a pipeline, and a first rotary discharge valve is mounted on the pipeline; a steam inlet pipe of the dryer is externally connected with low-pressure steam, a steam outlet pipe of the dryer is connected with the condensation tank, a gas dust outlet of the dryer is connected with the dust remover, and the dust remover is connected with the induced draft fan. According to the utility model, the spiral conveyer is arranged, so that the conveying of the lignite can be realized, the lignite can be accommodated, and the undried lignite or the undried lignite is prevented from entering the next process.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric power chemical equipment, and specifically relates to a low-pressure steam indirect drying system for lignite. Background Art

[0002] After drying, dehydration and quality improvement, most of the water in lignite can be removed, and the calorific value is significantly increased, which is conducive to the comprehensive utilization of lignite. Compared with other types of coal, lignite has a low ignition point. It can explode when the oxygen content in the environment reaches 12% to 18% and the coal powder temperature reaches 210℃ to 350℃. At present, the commonly used drum drying technology or fluidized bed drying technology generally reduces the moisture content in coal by less than 20%, which is not suitable for deep drying and large-scale utilization of lignite; moreover, in the above two drying technologies, the drying medium and lignite are in direct contact for heat exchange, and the drying medium temperature of the drum dryer is as high as 500℃ to 700℃, which is prone to explosion risks.

[0003] In view of the above-mentioned deficiencies of the prior art, a utility model patent with application number 201420452646.9, application date August 12, 2014, and invention titled "A system device for indirect drying of lignite with low-temperature steam" is provided, wherein a system device for indirect drying of lignite with low-temperature steam is provided. The raw coal bunker is connected to the coal feeder, the coal feeder is connected to the dryer, the dry coal outlet of the dryer is connected to the rotary seal feeding valve, the exhaust gas outlet of the dryer is connected to the dust collector, the condensate outlet of the dryer is connected to the condensate tank through a steam trap, the condensate tank is connected to the condensate pump, the outlet of the rotary seal feeding valve is connected to the buried scraper conveyor, the powder drop port of the dust collector is connected to the buried scraper conveyor, and the air outlet of the dust collector is connected to the fan.

[0004] Although the above technical solution can solve the shortcomings of the above existing technologies, after several years of operation, some areas that need to be optimized have also been found. For example, when the dryer is shut down, the lignite that is not dried properly will enter the next process, and the drying effect is not ideal; the coal powder in the dust collector is directly connected to the buried scraper conveyor through a vertical pipeline for discharge, and the coal powder is easy to scatter when falling, and the safety performance is poor; the operating temperature of the dryer and dust collector is not properly controlled, etc. Utility Model Content

[0005] In order to at least partially solve the above problems, the utility model provides a low-pressure steam indirect drying system for lignite, and its technical solution is as follows:

[0006] A low-pressure steam indirect drying system for lignite comprises a crusher, a raw coal bin, a coal feeder, a dryer, a screw conveyor, a first rotary discharge valve, a first buried scraper conveyor, a condenser, a dust collector and an induced draft fan; the crusher is connected to the raw coal bin, the raw coal bin is connected to the coal feeder, the coal feeder is connected to the particle bin of the dryer; the particle outlet of the dryer is connected to the screw conveyor, the screw conveyor is connected to the first buried scraper conveyor through a pipeline, and the first rotary discharge valve is installed on the pipeline; the steam inlet pipe of the dryer is externally connected to low-pressure steam, the steam outlet pipe of the dryer is connected to the condenser, the gas dust outlet of the dryer is connected to the dust collector, and the dust collector is connected to the induced draft fan.

[0007] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: the feed port of the screw conveyor is located below the particle outlet, and the discharge port of the screw conveyor is located above the first buried scraper conveyor; when the screw shaft of the screw conveyor rotates forward, the dried lignite is conveyed from the feed port to the discharge port; when the screw shaft of the screw conveyor rotates reversely, the dried lignite is conveyed from the discharge port to the feed port.

[0008] The low-pressure steam indirect drying system for lignite as described above is further preferably further provided with: a second buried scraper conveyor and a second rotary unloading valve; the dust collector is connected to the second buried scraper conveyor via a pipeline, and is used for unloading the filtered coal powder onto the second buried scraper conveyor; the second rotary unloading valve is installed on the pipeline, and is used for controlling the opening degree when unloading the coal powder.

[0009] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: the dust collector is provided with an ash hopper, which is in the shape of an inverted cone and is used for temporarily storing filtered coal powder.

[0010] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: a radio frequency admittance switch is installed on the ash hopper, and the radio frequency admittance switch is used to detect the material level in the ash hopper.

[0011] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: an armored thermal resistor is installed on the ash hopper, and the armored thermal resistor is used to detect the temperature of the coal powder in the ash hopper.

[0012] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: a carbon monoxide analyzer and an oxygen analyzer are installed at the air outlet of the dust collector; the carbon monoxide analyzer is used to detect the concentration of carbon monoxide, and the oxygen analyzer is used to detect the concentration of oxygen.

[0013] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: a double platinum thermal resistor is installed at the particle outlet, and the double platinum thermal resistor is used to detect the temperature at the particle outlet.

[0014] The low-pressure steam indirect drying system for lignite as described above is further preferably further provided with: a compressed gas tank connected to the dust collector for filling nitrogen into the dust collector when the temperature detected by the armored thermal resistor exceeds 90°C.

[0015] The low-pressure steam indirect drying system for lignite as described above is further preferably configured such that: the coal feeder is an electronic weighing coal feeder.

[0016] It can be seen from the analysis that compared with the prior art, the advantages and beneficial effects of the utility model are:

[0017] The utility model arranges a screw conveyor between the dryer and the first rotary discharge valve. During the operation of the system, the screw conveyor can realize the transportation of lignite; it can also play the role of accommodating lignite, providing a temporary accommodation space for the lignite dried by the dryer. Therefore, it can provide a response to the normal shutdown or fault shutdown of the dryer during the operation of the system, avoid the lignite that has not been dried or is not dried properly from entering the next process, and improve the drying effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The connection diagram of the low-pressure steam indirect drying system for lignite of the utility model is shown in FIG. Figure 1 ;

[0019] Figure 2 The connection diagram of the low-pressure steam indirect drying system for lignite of the utility model is shown in FIG. Figure 2 .

[0020] In the figure: 1-crusher; 2-raw coal bin; 3-coal feeder; 4-dryer; 5-screw conveyor; 6-first rotary discharge valve; 7-dust collector; 8-induced draft fan; 9-second rotary discharge valve; 10-first buried scraper conveyor; 11-second buried scraper conveyor; 12-compressed gas tank; 13-condensate tank. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "connected" and "connection" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0023] like Figure 1 As shown, in one embodiment of the utility model, a low-pressure steam indirect drying system for lignite is provided. Specifically, the low-pressure steam indirect drying system for lignite includes a crusher 1, a raw coal bin 2, a coal feeder 3, a dryer 4, a screw conveyor 5, a first rotary discharge valve 6, a first buried scraper conveyor 10, a condenser 13, a dust collector 7 and an induced draft fan 8. Among them, the crusher 1 is connected to the raw coal bin 2, the raw coal bin 2 is connected to the coal feeder 3, and the coal feeder 3 is connected to the particle bin of the dryer 4. The particle outlet of the dryer 4 is connected to the screw conveyor 5, the screw conveyor 5 is connected to the first buried scraper conveyor 10 through a pipeline, and the first rotary discharge valve 6 is installed on the pipeline. The steam inlet pipe of the dryer 4 is externally connected to low-pressure steam, the steam outlet pipe of the dryer 4 is connected to the condenser 13, the gas dust outlet of the dryer 4 is connected to the dust collector 7, and the dust collector 7 is connected to the induced draft fan 8.

[0024] In this embodiment, the lignite with a moisture content of 30% to 50% is crushed to a particle size of ≤20mm by the crusher 1, and then enters the dryer 4 from the raw coal bin 2 through the coal feeder 3 and the particle silo. The lignite exchanges heat with low-pressure steam in the dryer 4 to evaporate the moisture. The low-pressure steam has a pressure of 0.4MpaG to 0.6MpaG and a temperature of 140℃ to 175℃, and enters the dryer 4 through the steam inlet pipe. After heat exchange, the low-pressure steam becomes condensate and enters the condensation tank 13; the dried coal comes out from the particle outlet, passes through the screw conveyor 5 and the first rotary discharge valve 6 in sequence, and enters the first buried scraper conveyor 11; the moisture in the lignite is filtered by the dust collector 7 under the suction of the induced draft fan 8 and then discharged into the atmosphere; the coal powder in the moisture is filtered by the dust collector 7. In this embodiment, a screw conveyor 5 is arranged between the dryer 4 and the first rotary discharge valve 6. During the operation of the system, the screw conveyor 5 can realize the transportation of lignite; it can also play the role of accommodating lignite, providing a temporary accommodation space for the lignite dried by the dryer 4. Therefore, it can provide a response to the normal shutdown or fault shutdown of the dryer 4 during the operation of the system, prevent the undried lignite or the lignite that is not dried properly from entering the next process, and improve the lignite drying effect.

[0025] Furthermore, in this embodiment, the feed port of the screw conveyor 5 is located below the particle outlet, so as to receive the lignite discharged from the dryer 4. The discharge port of the screw conveyor 5 is located above the first buried scraper conveyor 10, so as to convey the lignite to the first buried scraper conveyor 10. Preferably, the screw conveyor 5 is provided with a forward and reverse rotation function. Specifically, when the screw shaft of the screw conveyor 5 rotates forward, the dried lignite is conveyed from the feed port to the discharge port, so as to realize the normal conveyance of the lignite; when the screw shaft of the screw conveyor 5 is reversed, the dried lignite is conveyed from the discharge port to the feed port. When the dryer 4 stops due to a fault, the screw shaft of the screw conveyor 5 can be reversed to discharge the coal with a shallow drying depth (not reaching the predetermined drying parameters) to prevent it from entering the next process.

[0026] like Figure 2 As shown, in one embodiment of the utility model, a second buried scraper conveyor 11 and a second rotary discharge valve 9 are also included, which can cooperate with the dust collector 7 to transport the filtered coal powder. Specifically, the dust collector 7 is connected to the second buried scraper conveyor 11 through a pipeline, and can unload the filtered coal powder onto the second buried scraper conveyor 11; the second rotary discharge valve 9 is installed on the pipeline, and can control the opening degree when the coal powder is unloaded. In this embodiment, the filtered coal powder is transported by the second buried scraper conveyor 11 instead of the first buried scraper conveyor 10, so that the dried lignite and coal powder can be distinguished and sent to different processes for use. The second rotary discharge valve 9 plays a role of continuous feeding and locking by controlling the opening degree when the coal powder is unloaded, which can prevent the coal powder from scattering during the falling process, improve safety, and avoid environmental pollution.

[0027] like Figure 2 As shown, in one embodiment of the utility model, the dust collector 7 is provided with an ash hopper, and the coal powder filtered by the dust collector 7 can be temporarily stored in the ash hopper. The ash hopper is in an inverted cone shape, which is convenient for the coal powder to be collected and discharged. In order to facilitate the detection of the material level in the ash hopper, a radio frequency admittance switch is installed on the ash hopper. The radio frequency admittance switch can detect the material level in the ash hopper for reference when regulating the operating status of the system. When the radio frequency admittance switch issues a high material level alarm, the system stops running.

[0028] Furthermore, in this embodiment, an armored thermal resistor is installed on the ash hopper, which can detect the temperature of the coal powder in the ash hopper in real time, provide data reference, and prevent the occurrence of safety accidents. At the same time, a double platinum thermal resistor is installed at the particle outlet of the dryer 4, which can detect the temperature at the particle outlet in real time.

[0029] Furthermore, in this embodiment, a carbon monoxide analyzer and an oxygen analyzer are installed at the air outlet of the dust collector 7. The carbon monoxide analyzer can detect the concentration of carbon monoxide; the oxygen analyzer can detect the concentration of oxygen, thereby providing data reference for the safe operation of the system, so that the operator can take control measures when the carbon monoxide concentration and / or oxygen concentration exceeds the standard.

[0030] like Figure 2 As shown, in one embodiment of the utility model, a compressed gas tank 12 is also included. Nitrogen is stored in the compressed gas tank 12, and nitrogen can be ejected outward when the valve is opened to provide gas protection. Specifically, the compressed gas tank 12 is connected to the dust collector 7. When the temperature detected by the armored thermal resistor exceeds 90°C, the valve of the compressed gas tank 12 is opened, and nitrogen can be filled into the dust collector 7, thereby reducing the temperature in the dust collector 7 and avoiding explosion in the dust collector 7; when the carbon monoxide concentration and / or oxygen concentration exceed the standard, the valve of the compressed gas tank 12 is opened, and nitrogen can be filled into the dust collector 7 to avoid explosion in the dust collector 7.

[0031] Optionally, in one embodiment of the utility model, the compressed gas tank 12 can also be selected to be connected to the air inlet of the dryer 4. When the temperature detected by the double platinum thermal resistor exceeds 90°C, the valve of the compressed gas tank 12 opens, and nitrogen can be filled into the dryer 4. One function is to lower the temperature and have a cooling effect. Second, it can also increase the content of inert gas (nitrogen) in the dryer 4 to avoid explosion in the dryer 4.

[0032] In one embodiment of the present invention, the coal feeder 3 is an electronic weighing coal feeder, which can measure the weight of the coal when feeding coal.

[0033] like Figure 2 As shown, the working process of the utility model is described in detail below:

[0034] Lignite with a moisture content of 30% to 50% is crushed to a particle size of ≤20mm by a crusher 1 and then enters a dryer 4 from a raw coal bin 2 through an electronic weighing coal feeder. In the dryer 4, the lignite exchanges heat with low-pressure steam to evaporate moisture; the low-pressure steam is converted into condensate after heat exchange and enters a condensate tank 13, and finally enters a condensate process network, which can be fully recovered and recycled; the dried coal comes out of the particle outlet and enters the first buried scraper conveyor 10 through a screw conveyor 5 and a first rotary discharge valve 6 in sequence; the moisture in the coal is filtered by a dust collector 7 under the suction of an induced draft fan 8 and then discharged into the atmosphere; the coal powder filtered by the dust collector 7 enters the second buried scraper conveyor 11 through a second rotary discharge valve 9. An armored thermal resistor is installed on the ash hopper of the dust collector 7 to detect the temperature in real time; a carbon monoxide analyzer and an oxygen analyzer are installed at the air outlet of the dust collector 7 to analyze the carbon monoxide content and oxygen content in real time; a radio frequency admittance switch is installed on the ash hopper of the dust collector 7 to detect the material level of the coal powder in the ash hopper in real time; a double platinum thermal resistor is installed at the particle outlet of the dryer 4 to detect the temperature in real time.

[0035] When the double platinum thermal resistor detects that the dry coal temperature exceeds 90°C, the compressed gas tank 12 fills nitrogen into the dryer; when the armored thermal resistor detects that the coal powder temperature exceeds 90°C, the compressed gas tank 12 fills nitrogen into the dust collector 7; when the carbon monoxide concentration detected by the carbon monoxide analyzer exceeds 90ppm, the compressed gas tank 12 fills nitrogen into the dust collector 7; when the oxygen analyzer detects that the oxygen volume content exceeds 12%, the compressed gas tank 12 fills nitrogen into the dust collector 7. When the radio frequency admittance switch detects that the coal powder level in the ash hopper exceeds the predetermined height, an alarm is issued and the system stops running.

[0036] In order to meet the requirements of drying quality, the steam volume, the coal feeding volume of the coal feeder 3, and the rotation speed of the dryer 4 are adapted. The screw conveyor 5 has a forward and reverse function. When the system fails and stops, the screw conveyor 5 can be turned over to discharge the coal with a shallow drying depth to avoid entering the next process. The oxygen analyzer and the carbon monoxide analyzer cooperate with the compressed gas tank 12 during detection. The oxygen volume content is controlled below 12Vol% when the dryer 4 is operating normally, and is controlled below 8Vol% when the dryer 4 is stopped or restarted. The carbon monoxide concentration is always controlled below 90ppm. The low-pressure steam indirect drying lignite system of the utility model has good drying effect, good safety performance, and easy temperature control, and is more suitable for large-scale industrial application of lignite.

[0037] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the embodiments disclosed above are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A low-pressure steam indirect drying system for lignite, characterized in that: include: Crusher, raw coal bunker, coal feeder, dryer, screw conveyor, first rotary discharge valve, first buried scraper conveyor, condensate tank, dust collector and induced draft fan; The crusher is connected to the raw coal bunker, the raw coal bunker is connected to the coal feeder, and the coal feeder is connected to the particle bunker of the dryer; The particle outlet of the dryer is connected to the screw conveyor, the screw conveyor is connected to the first buried scraper conveyor through a pipeline, and the first rotary discharge valve is installed on the pipeline; The steam inlet pipe of the dryer is externally connected to low-pressure steam, the steam outlet pipe of the dryer is connected to the condenser, the gas dust outlet of the dryer is connected to the dust collector, and the dust collector is connected to the induced draft fan.

2. The low-pressure steam indirect drying system for lignite according to claim 1, characterized in that: The feed port of the screw conveyor is located below the particle outlet, and the discharge port of the screw conveyor is located above the first buried scraper conveyor; When the screw shaft of the screw conveyor rotates forward, the dried lignite is conveyed from the feed port to the discharge port; When the screw shaft of the screw conveyor is reversed, the dried lignite is transported from the discharge port to the feed port.

3. The low-pressure steam indirect drying system for lignite according to claim 1, characterized in that: Also included is a second buried scraper conveyor and a second rotary discharge valve; The dust collector is connected to the second buried scraper conveyor through a pipeline, and is used to unload the filtered coal powder onto the second buried scraper conveyor; The second rotary discharge valve is installed on the pipeline and is used to control the opening degree during coal powder discharge.

4. The low-pressure steam indirect drying system for lignite according to claim 1, characterized in that: The dust collector is provided with an ash hopper which is in an inverted cone shape and is used for temporarily storing filtered coal powder.

5. The low-pressure steam indirect drying system for lignite according to claim 4, characterized in that: The ash hopper is provided with a radio frequency admittance switch, and the radio frequency admittance switch is used to detect the material level in the ash hopper.

6. The low-pressure steam indirect drying system for lignite according to claim 4, characterized in that: An armored thermal resistor is installed on the ash hopper, and the armored thermal resistor is used to detect the temperature of the coal powder in the ash hopper.

7. The low-pressure steam indirect drying system for lignite according to claim 1, characterized in that: The air outlet of the dust collector is equipped with a carbon monoxide analyzer and an oxygen analyzer; The carbon monoxide analyzer is used to detect the concentration of carbon monoxide, and the oxygen analyzer is used to detect the concentration of oxygen.

8. The low-pressure steam indirect drying system for lignite according to claim 5, characterized in that: A double platinum thermal resistor is installed at the particle outlet, and the double platinum thermal resistor is used to detect the temperature at the particle outlet.

9. The low-pressure steam indirect drying system for lignite according to claim 6, characterized in that: It also includes a compressed gas tank, which is connected to the dust collector and is used to fill nitrogen into the dust collector when the temperature detected by the armored thermal resistor exceeds 90°C.

10. The low-pressure steam indirect drying system for lignite according to claim 1, characterized in that: The coal feeder is an electronic weighing coal feeder.

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