Low-order pulverized coal electric heating upgrading process and system

Abstract

The invention relates to the technical field of low-rank coal upgrading, in particular to a low-rank pulverized coal electric heating upgrading process and system. The low-order pulverized coal electric heating upgrading system comprises a feeding unit, a low-order pulverized coal electric heating upgrading device, a coal and coke mixing heat exchange screening unit and a coal gas power generation unit. The low-order pulverized coal dry distillation upgrading process is achieved in an electric heating mode, and compared with a low-order pulverized coal dry distillation furnace adopting traditional chemical fuel, the device is simpler in structure and more accurate in temperature regulation and control; a regional green power grid is preferentially adopted for power supply, and a public power grid is used as supplement, so that heating energy is cleaner; after the dry-distilled semicoke is mixed with the small-particle coal for heat exchange, small-particle upgraded coal can also be obtained; and the process system is efficient, economical and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of low-rank coal upgrading, and particularly to a low-rank pulverized coal electro-heating upgrading process and system. Background Art

[0002] The reserves of low-rank coal in China are nearly 500 billion tons, accounting for about 42% of the total proven coal reserves. Among them, low-rank pulverized coal (low-rank coal with a particle size <6 mm) accounts for 20% - 30% of the total reserves of low-rank coal. The low-rank coal deposits in China are mainly distributed in western regions such as Shaanxi, Inner Mongolia, and Xinjiang, accounting for about 57.38% of the total predicted reserves of national coal resources. Low-rank coal upgrading refers to improving the quality of low-rank coal (such as lignite and sub-bituminous coal) through physical, chemical, or biological methods to increase its calorific value, combustion efficiency, and applicability. Low-rank coal upgrading is of great significance for improving energy efficiency, reducing pollution, expanding applications, enhancing economic benefits, making full use of resources, and promoting technological progress, and is the key to realizing the efficient and clean utilization of coal resources.

[0003] The current low-rank coal upgrading processes include the integrated comprehensive upgrading technology of low-rank coal (CHT upgrading technology), the low-rank coal pyrolysis process in the United States (LFC process), the Lurgi Ruhr pyrolysis process in Germany (L-R process), the Toscoal pyrolysis process in the United States (Toscoal process), the Garrett pyrolysis process in the United States (Garrett process), the gas pyrolysis process in the United States (CODE process), the gas pyrolysis process in Japan (ECOPRO process), etc. The above processes are applicable to large-sized coal and small-sized coal, and gas and air are used for heating during the process. During the gas-solid heat transfer and flow process, due to the existence of powdered pulverized coal, dust is easily formed inside the process system, resulting in poor air permeability and low heat transfer efficiency, and ultimately leading to unsatisfactory industrialization effects.

[0004] At present, green electricity is widely used in commercial, industrial, and other fields. The application of green electricity helps to reduce greenhouse gas emissions and atmospheric pollutant emissions, and slow down the processes of global climate change and air pollution. In addition, green electricity has many sources, including wind energy, solar energy, hydropower, geothermal energy, and ocean energy, and has sustainability and environmental friendliness. However, the disadvantages of green electricity are unstable power generation, high operating costs, insufficient energy storage technology, and depreciation problems, resulting in it being difficult for green electricity to achieve continuous industrial applications. Although the combined application of green electricity and the power grid can obtain a lasting and stable power supply, after the large-scale application of green electricity, its compatibility with the power grid is not high, and the compatibility and security issues between the green energy power generation system and the traditional power system have not been fully resolved.

[0005] In view of the above problems, a multi-mode linkage low-rank pulverized coal electrothermal upgrading process and device are developed, which effectively apply the linkage of green power and the power grid, and a new process for continuously and stably supplying power to the low-rank pulverized coal upgrading device in balance within the industrial area. The low-rank pulverized coal is upgraded by using the linkage power supply heating of the power grid and green power, abandoning the disadvantages of other low-rank coal pyrolysis devices. According to the electrothermal mechanism, a new device for supplying low-rank pulverized coal by the linkage of the power grid and green power is developed. The structure is reconstructed, and the heating energy is electrothermal, which is pollution-free, energy-saving, and reduces the construction cost. Summary of the Invention

[0006] The present invention provides a low-rank pulverized coal electrothermal upgrading process and system, which realizes the dry distillation upgrading process of low-rank pulverized coal by electrothermal heating. Compared with the low-rank pulverized coal dry distillation furnace using traditional chemical fuels, the device structure is simpler and the temperature control is more accurate; and the regional green power grid is preferentially used for power supply, and the public power grid is used as a supplement, making the heating energy cleaner; after the dry distillation, the semi-coke and small-grained coal are mixed and heat-exchanged to obtain small-grained upgraded coal; the process system is efficient, economical, and environmentally friendly.

[0007] In order to achieve the above object, the present invention is realized by adopting the following technical solutions:

[0008] A low-rank pulverized coal electrothermal upgrading process includes the following steps:

[0009] 1) The low-rank pulverized coal raw material with a particle size < 6 mm transported by the coal preparation unit enters the coal storage bin, is controlled by the coal storage bin feed valve to enter the buffer bin, and then is controlled by the coal storage bin feed valve to enter the auxiliary coal bin;

[0010] 2) The auxiliary coal bin uses multi-channel feeding. The low-rank pulverized coal electrothermal upgrading device consists of a plurality of upgrading chambers and electrothermal chambers arranged at intervals. The electrothermal chamber is provided with an electrothermal device, and the electrothermal device is jointly powered by the regional green power grid and the public power grid; the low-rank pulverized coal raw material is evenly loaded into each upgrading chamber through a plurality of feeding channels, and then moves downward from top to bottom;

[0011] 3) The upgrading chamber is successively provided with a preheating section, a dry distillation section, and a coke discharging section from top to bottom. The low-rank pulverized coal is in countercurrent contact with the raw gas generated in the preheating section and the dry distillation section, and is heated to 320 - 380 °C; the low-rank pulverized coal continues to move downward into the dry distillation section, is heated to 650 - 780 °C and becomes high-temperature semi-coke, and the high-temperature semi-coke is discharged through the coke discharging bin;

[0012] 4) The high-temperature semi-coke discharged from the coke discharging bin falls onto the coal-coke mixing conveyor, is mixed with the small-grained pulverized coal with a particle size < 1 mm transported by the small-grained coal conveyor, and then enters the coal-coke heat exchange bin; after heat exchange and screening, small-grained upgraded coal with a temperature above 200 °C and semi-coke with a temperature below 300 °C are obtained;

[0013] 5) The upgraded coal gas generated during the low-rank pulverized coal dry distillation process is collected by the gas collecting umbrella and enters the outlet gas pipeline through the upgraded coal gas outlet. In the outlet gas pipeline, the upgraded coal gas is cooled to 70-80 °C by spraying circulating ammonia water. The cooled upgraded coal gas and the condensed ammonia water-coal tar mixture enter the gas purification device together;

[0014] 6) After the upgraded coal gas enters the gas purification device for treatment, part of it is used for industrial production, and the other part generates green electricity through self-generation. The green electricity is supplied to the low-rank pulverized coal electro-heating upgrading device through the regional green electricity grid, realizing the recycling of energy.

[0015] A low-rank pulverized coal electro-heating upgrading system includes a feeding unit, a low-rank pulverized coal electro-heating upgrading device, a coal-coke mixed heat exchange and screening unit, and a gas power generation unit; the low-rank pulverized coal electro-heating upgrading device consists of a device body and multiple upgrading chambers and electric heating chambers arranged alternately inside the device body. Multiple electric heating devices are arranged inside the electric heating chambers; a coal material inlet is arranged at the top of the upgrading chamber, and a semi-coke outlet is arranged at the bottom; the feeding unit is arranged above the low-rank pulverized coal electro-heating upgrading device, adopts a multi-stage closed feeding structure, and is connected to the coal material inlet of the upgrading chamber through multiple discharge ports; a coke discharging bin is arranged at the bottom of the upgrading chamber; the coal-coke mixed heat exchange and screening unit consists of a coal-coke mixed conveyor, a small-grained coal conveyor, a coal-coke heat exchange bin, and a screening device; the coal-coke mixed conveyor is arranged along the arrangement direction of the coke discharging bin. The feeding end of the coal-coke mixed conveyor is connected to the small-grained coal conveyor, and the discharging end of the coal-coke mixed conveyor is connected to the coal-coke heat exchange bin; a screening device is arranged at the discharging port of the coal-coke heat exchange bin; a upgraded coal gas outlet is arranged at the top of the upgrading chamber, and the upgraded coal gas outlet is connected to the gas purification device. One branch of the purified gas outlet of the gas purification device is connected to the gas power generation unit, and the gas power generation unit is connected to the regional green electricity grid; the electric heating device is connected to the power grid through a power line. The power grid includes a regional green electricity grid and a public power grid connected in parallel, and power control valves are respectively arranged at the corresponding input ends of the regional green electricity grid and the public power grid.

[0016] The feeding unit consists of multiple coal storage bins, multiple buffer coal bins, and multiple auxiliary coal bins. The coal storage bins, buffer coal bins, and auxiliary coal bins are all arranged in one-to-one correspondence with the upgrading chambers; a coal loading port is arranged at the top of the coal storage bin, and a coal storage bin feeding valve is arranged at the bottom outlet of the coal storage bin; the buffer coal bin has a closed bin body. The feeding port at the top of the buffer coal bin is connected to the bottom outlet of the corresponding coal storage bin, and a buffer coal bin feeding valve is arranged at the bottom outlet of the buffer coal bin; the auxiliary coal bin is a multi-channel structure. The feeding port at the top of the auxiliary coal bin is connected to the bottom outlet of the corresponding buffer coal bin, and multiple discharging ports of the auxiliary coal bin are connected to the coal material inlets of the corresponding upgrading chambers, and the multiple discharging ports are evenly distributed along the circumferential direction of the upgrading chamber.

[0017] The quality improvement chamber is of a vertical cylindrical structure, and a shunt tower is arranged in the middle of the quality improvement chamber. The quality improvement chamber is successively divided into a preheating section, a dry distillation section and a coke discharging section from top to bottom. A quality-improved gas outlet is arranged at the top of the quality improvement chamber, and a coke discharging bin is arranged at the bottom of the quality improvement chamber.

[0018] A plurality of heating channels are uniformly arranged in the electric heating chamber along the direction parallel to the quality improvement chamber, and openings are arranged at the tops of the heating channels. Electric heating devices are correspondingly arranged in the heating channels. A refractory material layer is arranged on the side of the electric heating chamber close to the quality improvement chamber. A heat insulation layer is arranged on the side of the electric heating chamber located on the periphery of the low-rank pulverized coal electrothermal quality improvement device close to the device body. The device body is composed of an inner wall and an outer steel structure shell.

[0019] The electric heating device is an electric heating device with segmented heating and segmented control. Temperature detection devices are respectively arranged in the preheating section, the dry distillation section and the coke discharging section of the quality improvement chamber. The signal output ends of the temperature detection devices are connected to the control ends of the electric heating devices through a control system.

[0020] A gas collecting umbrella is arranged at the upper part of the quality improvement chamber. The quality-improved gas outlet is connected to a gas purification device through an outlet gas pipeline. An ammonia water spraying device is arranged in the outlet gas pipeline, and a gas temperature detection device is arranged on the outlet gas pipeline downstream of the ammonia water spraying device. An ammonia water flow regulating valve and an ammonia water flow detection device are arranged on the ammonia water conveying pipeline of the ammonia water spraying device. The signal output ends of the gas temperature detection device and the ammonia water flow detection device are respectively connected to the control system, and the control system is additionally connected to the control end of the ammonia water flow regulating valve.

[0021] An exhaust port is arranged at the top of the coal coke heat exchange bin and is connected to the gas purification device through a pipeline.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) By adopting the mode of linking the regional green power grid with the public power grid, the purpose of stable power output is achieved through the complementary regulation of the public power grid on the regional green power grid, that is, when the green power can be stably and continuously output, the regional green power grid supplies power to the low-rank pulverized coal electrothermal quality improvement device, and when the green power is unstable, the public power grid supplements the electric energy to achieve the power balance in the system, so as to provide lasting and stable electric energy for the low-rank pulverized coal electrothermal quality improvement process;

[0024] (2) The low-rank pulverized coal electrothermal quality improvement device comprises a plurality of quality improvement chambers, electric heating devices are evenly distributed on both sides of each quality improvement chamber, the electric heating devices are connected to the external power grid, and through the interlocking of the temperature measuring devices in each functional section of the quality improvement chamber and the electric heating devices that can be heated and controlled in segments, the precise control of the temperature in the low-rank pulverized coal quality improvement process is realized;

[0025] (3) A set of feeding unit and a set of coke discharging unit are shared by multiple upgrading chambers, which is beneficial to reducing equipment costs. The feeding unit adopts a double-bin and double-valve structure, and there is no external exhaust gas during the dry distillation process, achieving the environmental protection goal.

[0026] (4) The low-rank pulverized coal electro-heating upgrading device, as the core equipment of the system described in the present invention, is composed of multiple upgrading chambers and multiple electro-heating chambers arranged alternately. Multiple groups of electro-heating devices are arranged in the electro-heating chambers as heat sources to ensure uniform heating during the dry distillation of low-rank pulverized coal.

[0027] (5) The semi-coke after dry distillation is mixed with small-particle pulverized coal and then transported to the coal-coke heat exchange bin for heat exchange, and then two materials, namely small-particle upgraded coal and semi-coke, are obtained after screening.

[0028] (6) A refractory material layer is provided on the side of the electro-heating chamber close to the upgrading chamber, and a heat insulation layer is provided on the side close to the wall. The outermost layer of the low-rank pulverized coal electro-heating upgrading device is a steel structure shell. The electro-heating material has little plastic change at high temperatures and is embedded in the corresponding heating channels of the electro-heating chamber. The electro-heating elements are not easily deformed, which is beneficial to extending the service life and is easy to achieve group temperature control and precise temperature control.

[0029] (6) A gas collecting umbrella is provided inside the low-rank pulverized coal electro-heating upgrading device, which is beneficial to the smooth discharge of the gas generated in the upgrading chamber. An ammonia water spraying device is arranged in the outlet gas pipeline, and the ammonia water flow is controlled by interlocking with the upgrading gas temperature detection device to achieve the effect of effectively cooling and purifying the gas. Description of the Drawings

[0030] Figure 1 is the flow chart of the low-rank pulverized coal electro-heating upgrading process described in the present invention.

[0031] Figure 2 is the structural schematic diagram of the low-rank pulverized coal electro-heating upgrading system described in the present invention.

[0032] Figure 3 is the horizontal sectional view of the low-rank pulverized coal electro-heating upgrading device described in the present invention.

[0033] In the figure: 1. Coal storage bin; 2. Coal storage bin feeding valve; 3. Buffer coal bin; 4. Buffer coal bin feeding valve; 5. Auxiliary coal bin; 6. Electro-heating device; 7. Shunt tower; 8. Low-rank pulverized coal electro-heating upgrading device; 8.1. Upgrading chamber; 8.2. Electro-heating chamber; 8.3. Heat insulation layer; 8.4. Wall; 8.5. Steel structure shell; 8.6. Refractory material layer; 9. Coke discharging bin; 10. Coal-coke mixing conveyor; 11. Small-particle coal conveyor; 12. Coal-coke heat exchange bin; 13. Screening device; 14. Exhaust port; 15. Upgrading gas outlet; 16. Gas purification device. Detailed Embodiments

[0034] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings:

[0035] As Figure 1 shown, a low-rank pulverized coal electrothermal upgrading process of the present invention includes the following steps:

[0036] 1) Low-rank pulverized coal raw materials with a particle size < 6 mm conveyed by the coal preparation unit enter the coal storage bin 1, are controlled by the coal storage bin feed valve 2 to enter the buffer bin 3, and then are controlled by the coal storage bin feed valve 4 to enter the auxiliary coal bin 5;

[0037] 2) The auxiliary coal bin 5 uses multi-channel feeding. The low-rank pulverized coal electrothermal upgrading device 8 is composed of a plurality of upgrading chambers 8.1 and electrothermal chambers 8.2 arranged at intervals. An electrothermal device 6 is arranged in the electrothermal chamber 8.2, and the electrothermal device 6 is jointly powered by the regional green power grid and the public power grid; the low-rank pulverized coal raw materials are evenly loaded into each upgrading chamber 8.1 through a plurality of feeding channels and then move downward from top to bottom;

[0038] 3) The upgrading chamber 8.1 is successively provided with a preheating section, a dry distillation section, and a coke discharging section from top to bottom. The low-rank pulverized coal is in countercurrent contact with the raw gas generated in the preheating section and the dry distillation section and is heated to 320 - 380 °C; the low-rank pulverized coal continues to move downward into the dry distillation section, is heated to 650 - 780 °C and then becomes high-temperature semicoke, and the high-temperature semicoke is discharged through the coke discharging bin 9;

[0039] 4) The high-temperature semicoke discharged from the coke discharging bin 9 falls onto the coal-coke mixing conveyor 10, is mixed with small-particle pulverized coal with a particle size < 1 mm conveyed by the small-particle coal conveyor 11 and then enters the coal-coke heat exchange bin 12; after heat exchange and screening, small-particle upgraded coal with a temperature above 200 °C and semicoke with a temperature below 300 °C are obtained;

[0040] 5) The upgraded gas generated during the dry distillation of low-rank pulverized coal is collected by the gas collecting umbrella, enters the outlet gas pipeline through the upgraded gas outlet 15, and is cooled to 70 - 80 °C by spraying circulating ammonia water in the outlet gas pipeline. The cooled upgraded gas and the ammonia water coal tar mixture condensed together enter the gas purification device 16;

[0041] 6) After the upgraded gas enters the gas purification device 16 for treatment, a part of it is used for industrial production, and the other part generates green power through self-generation and supplies power to the low-rank pulverized coal electrothermal upgrading device 8 through the regional green power grid, realizing the recycling of energy.

[0042] The low-rank pulverized coal electrothermal upgrading system described in the present invention includes a feeding unit, a low-rank pulverized coal electrothermal upgrading device 8, a coal-coke mixed heat exchange and screening unit, and a gas power generation unit; the low-rank pulverized coal electrothermal upgrading device 8 consists of a device body and a plurality of upgrading chambers 8.1 and electroheating chambers 8.2 arranged alternately in the device body, and a plurality of electroheating devices 6 are arranged in the electroheating chamber 8.2; a coal material inlet is arranged at the top of the upgrading chamber 8.1, and a semi-coke outlet is arranged at the bottom; the feeding unit is arranged above the low-rank pulverized coal electrothermal upgrading device 8, adopts a multi-stage closed feeding structure and is connected to the coal material inlet of the upgrading chamber 8.1 through a plurality of discharge ports; a coke bin 9 is arranged at the bottom of the upgrading chamber 8.1; the coal-coke mixed heat exchange and screening unit consists of a coal-coke mixed conveyor 10, a small-particle coal conveyor 11, a coal-coke heat exchange bin 12, and a screening device 13; the coal-coke mixed conveyor 10 is arranged along the arrangement direction of the coke bin 9, the feeding end of the coal-coke mixed conveyor 10 is connected to the small-particle coal conveyor 11, and the discharging end of the coal-coke mixed conveyor 10 is connected to the coal-coke heat exchange bin 12; a screening device 13 is arranged at the discharge port of the coal-coke heat exchange bin 12; a upgrading gas outlet 15 is arranged at the top of the upgrading chamber 8.1, the upgrading gas outlet 15 is connected to a gas purification device 16, a purified gas outlet of the gas purification device 16 branches out a path to connect to the gas power generation unit, and the gas power generation unit is connected to the regional green power grid; the electroheating device 6 is connected to the power grid through a power line, the power grid includes a regional green power grid and a public power grid connected in parallel, and power control valves are respectively arranged at the corresponding input ends of the regional green power grid and the public power grid.

[0043] The feeding unit consists of a plurality of coal storage bins 1, a plurality of buffer coal bins 3, and a plurality of auxiliary coal bins 5. The coal storage bins 1, buffer coal bins 3, and auxiliary coal bins 5 are all arranged in one-to-one correspondence with the upgrading chamber 8.1; a coal loading port is arranged at the top of the coal storage bin 1, and a coal storage bin feeding valve 2 is arranged at the bottom outlet of the coal storage bin 1; the buffer coal bin 3 has a closed bin body, the feeding port at the top of the buffer coal bin 3 is connected to the bottom outlet of the corresponding coal storage bin 1, and a buffer coal bin feeding valve 4 is arranged at the bottom outlet of the buffer coal bin 3; the auxiliary coal bin 5 is a multi-channel structure, the feeding port at the top of the auxiliary coal bin 5 is connected to the bottom outlet of the corresponding buffer coal bin 3, and a plurality of discharging ports of the auxiliary coal bin 5 are connected to the coal material inlet of the corresponding upgrading chamber 8.1, and the plurality of discharging ports are evenly distributed along the circumferential direction of the upgrading chamber 8.1.

[0044] The upgrading chamber 8.1 is of a vertical cylindrical structure, and a flow dividing tower 7 is arranged in the middle of the upgrading chamber 8.1; the upgrading chamber 8.1 is successively a preheating section, a dry distillation section, and a coke discharging section from top to bottom. A upgrading gas outlet 15 is arranged at the top of the upgrading chamber 8.1, and a coke bin 9 is arranged at the bottom of the upgrading chamber 8.1.

[0045] A plurality of heating channels are uniformly arranged in the electric heating chamber 8.2 along a direction parallel to the upgrading chamber 8.1, and openings are provided at the tops of the heating channels; electric heating devices 6 are correspondingly arranged in the heating channels one by one; a refractory material layer 8.6 is provided on the side of the electric heating chamber 8.2 close to the upgrading chamber 8.1; a heat insulation layer 8.3 is provided on the side of the electric heating chamber 8.2 located outside the low-rank pulverized coal electric heating upgrading device 8 close to the device body; the device body is composed of an inner wall 8.4 and an outer steel structure shell 8.5.

[0046] The electric heating device 6 is an electric heating device with segmented heating and segmented control. Temperature detection devices are respectively arranged in the preheating section, coking section and coke discharging section of the upgrading chamber 8.1, and the signal output ends of the temperature detection devices are connected to the control ends of the electric heating devices through a control system.

[0047] A gas collecting umbrella is provided at the upper part of the upgrading chamber 8.1; the upgraded gas outlet 15 is connected to a gas purification device 16 through an outlet gas pipeline; an ammonia water spraying device is arranged in the outlet gas pipeline, and a gas temperature detection device is arranged on the outlet gas pipeline downstream of the ammonia water spraying device; an ammonia water flow regulating valve and an ammonia water flow detection device are arranged on the ammonia water conveying pipeline of the ammonia water spraying device; the signal output ends of the gas temperature detection device and the ammonia water flow detection device are respectively connected to the control system, and the control system is additionally connected to the control end of the ammonia water flow regulating valve.

[0048] An exhaust port is provided at the top of the coal coke heat exchange bin 12 and is connected to the gas purification device 16 through a pipeline.

[0049] The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. The methods used in the following embodiments are all conventional methods unless otherwise specified.

[0050]

Embodiment

[0051] In this embodiment, the flow chart of the low-rank pulverized coal electric heating upgrading process is as Figure 1 shown. The regional green power grid and the public power grid cooperate to continuously and stably supply power to the low-rank pulverized coal electric heating upgrading device. When the regional green power grid can stably and continuously output electric energy, green power is preferentially used to supply power to the low-rank pulverized coal electric heating upgrading device; when the electric energy of the regional green power grid is unstable, the public power grid is used to supplement and adjust the green power electric energy to ensure that the system internally balances and continuously and stably supplies power to the low-rank pulverized coal electric heating upgrading device.

[0052] Raw coal (low-rank pulverized coal with a particle size < 6 mm) is pyrolyzed by the low-rank pulverized coal electrothermal upgrading device 8 to produce semicoke and upgraded coal gas. After the upgraded coal gas is processed by the gas purification device 16, a part of it enters industrial production, and the other part generates green electricity through the gas power generation unit and supplies power to the low-rank pulverized coal electrothermal upgrading device through the regional green electricity grid, realizing the recycling of energy.

[0053] As Figure 2 shown, it is a schematic structural diagram of the low-rank pulverized coal electrothermal upgrading system in the embodiment. The low-rank pulverized coal electrothermal upgrading system includes: a feeding unit, a low-rank pulverized coal electrothermal upgrading device 8, a coal-coke mixed heat exchange and screening unit, and a gas power generation unit (not shown in the figure).

[0054] In this embodiment, the low-rank pulverized coal electrothermal upgrading device 8 includes a plurality of upgrading chambers 8.1. The upgrading chamber 8.1 adopts a vertical cylindrical structure. On both sides of the upgrading chamber 8.1 are electric heating chambers 8.2, and a plurality of electric heating devices 6 are evenly distributed in the electric heating chamber 8.2. The electric heating device 6 is connected to an external power supply. The external power supply includes regionally generated green electricity (self-generated electricity) and electricity from the public power grid input in parallel. The regionally generated green electricity and the electricity from the public power grid are switched or shared through corresponding power control valves.

[0055] At the top of the upgrading chamber 8.1 are provided a coal feed inlet and an upgraded coal gas outlet 15. The upgraded coal gas generated after the low-rank pulverized coal is pyrolyzed enters the subsequent gas purification device 16 through the gas outlet pipeline. At the top of the coal feed inlet, a coal storage bin 1, a buffer coal bin 3, and an auxiliary coal bin 5 are arranged from top to bottom in sequence. The three are connected by a coal storage bin feed valve 2 and a buffer coal bin feed valve 4, forming a double-bin and double-valve structure. The buffer coal bin 3 with a closed structure is used to isolate the inside from the external gas phase when loading materials into the upgrading chamber 8.1. A set of feeding units and a set of coke discharging units are adopted for multiple upgrading chambers 8.1.

[0056] At the bottom of the upgrading chamber 8.1 is provided a coke discharging bin 9. The semicoke discharged from the coke discharging bin 9 is mixed with the pulverized coal with a particle size < 1 mm conveyed by the small-particle coal conveyor 11, and then sent to the coal-coke heat exchange bin 12 through the coal-coke mixed conveyor 10. After sufficient heat exchange, it is screened by the screening device 13 to obtain two materials: small-particle upgraded coal and semicoke. The small-particle upgraded coal is used for power generation.

[0057] As Figure 3 shown, it is a cross-sectional schematic diagram of the low-rank pulverized coal electrothermal upgrading device 8 in this embodiment. Electric heating chambers 8.2 are provided on both sides of each upgrading chamber 8.1, and a plurality of electric heating devices 6 are evenly distributed in the electric heating chamber 8.2. The electric heating device 6 is installed in a circular groove-shaped heating channel. Each electric heating device 6 is composed of multiple sections of wound electric heating wires, and each section of electric heating wire is correspondingly provided with a set of temperature control devices, having the function of grouped and segmented temperature control, thereby realizing the automatic and precise temperature control process of the low-rank pulverized coal electrothermal upgrading device 8.

[0058] In this embodiment, the qualified low-rank pulverized coal raw materials transported by the coal preparation unit first enter the coal storage bin 1, enter the buffer bin 3 through the coal storage bin feeding valve 2, then enter the auxiliary coal bin 5 through the coal storage bin feeding valve 4, and are evenly loaded into the upgrading chamber 8.1 through multiple feeding channels of the auxiliary coal bin 5. The low-rank pulverized coal added to the upgrading chamber 8.1 moves from top to bottom and contacts the raw gas produced in the dry distillation section in a countercurrent manner; in the preheating section at the upper part of the upgrading chamber 8.1, the low-rank pulverized coal is heated to 350 °C; the low-rank pulverized coal continues to move downward into the dry distillation section in the middle of the upgrading chamber 8.1 and is heated to 720 °C, and semi-coke is formed through dry distillation; the high-temperature semi-coke is discharged through the coke discharging bin 9 below, and the coke discharging speed is controlled by controlling the speed of the coal-coke mixing conveyor; after the high-temperature semi-coke is mixed with the small-particle pulverized coal conveyed by the small-particle coal conveyor 11, it is continuously sent to the coal-coke heat exchange bin 12 through the coal-coke mixing conveyor 10, and after sufficient heat exchange, it is screened by the screening device 13 to obtain small-particle upgraded coal at a temperature of 200 °C and semi-coke at a temperature of 200 °C.

[0059] The electric heating chamber 8.2 is arranged at intervals inside the device body, used to provide heat for the upgrading chamber 8.1 and ensure that the low-rank pulverized coal is evenly heated. The electric heating chamber 8.2 is provided with a refractory material layer 8.6 on the side close to the upgrading chamber 8.1, and an insulating layer 8.3 on the side close to the device body. The outside of the insulating layer 8.3 is successively a wall 8.4 and a steel structure shell 8.5.

[0060] In this embodiment, the upgraded gas generated during the dry distillation and upgrading process of the low-rank pulverized coal raw materials is collected by the gas collecting umbrella, enters the gas outlet pipeline through the upgraded gas outlet 15, and is cooled to 70 - 80 °C by spraying circulating ammonia water. The cooled upgraded gas and the condensed ammonia water coal tar mixture enter the gas purification device 16 together. After the upgraded gas enters the gas purification device 16 for treatment, part of it is used for industrial production, and the other part generates green electricity through self-generation of the gas power generation unit, and supplies power to the low-rank pulverized coal electric heating upgrading device 8 through the regional green electricity grid, realizing the recycling of energy.

[0061] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A process for upgrading the quality of low-grade pulverized coal by electric heating, characterized in that: The steps include: 1) The low-grade pulverized coal raw materials with a particle size of less than 6mm delivered by the coal preparation unit enter the coal storage bunker, are controlled by the coal storage bunker feeding valve to enter the buffer bunker, and then are controlled by the coal storage bunker feeding valve to enter the auxiliary coal bunker; 2) The auxiliary coal bunker adopts multi-channel unloading. The low-rank pulverized coal electric heating and upgrading device consists of multiple upgrading chambers and electric heating chambers arranged at intervals. The electric heating chamber is equipped with an electric heating device, which is jointly powered by the regional green power grid and the public power grid. The low-rank pulverized coal raw materials are evenly loaded into each upgrading chamber through multiple unloading channels, and then moved from top to bottom; 3) The quality-improving chamber is provided with a preheating section, a dry distillation section and a coke outlet section from top to bottom. The low-rank pulverized coal is countercurrently contacted with the raw coal gas produced in the dry distillation section in the preheating section and is heated to 320-380°C. The low-rank pulverized coal continues to move downward into the dry distillation section and is heated to 650-780°C to become high-temperature semi-coke, which is discharged through the coke outlet bin. 4) The high-temperature semi-coke discharged from the coke discharge bin falls onto the coal-coke mixing conveyor, is mixed with the small-particle pulverized coal with a particle size of less than 1 mm conveyed by the small-particle coal conveyor, and then enters the coal-coke heat exchange bin; after heat exchange and screening, small-particle upgraded coal with a temperature of more than 200°C and semi-coke with a temperature of less than 300°C are obtained; 5) The upgraded coal gas generated during the dry distillation of low-rank pulverized coal is collected by a gas collecting umbrella and enters the outlet coal gas pipeline from the upgraded coal gas outlet. The upgraded coal gas is cooled to 70-80°C by spraying circulating ammonia water in the outlet coal gas pipeline. The cooled upgraded coal gas and the condensed ammonia water coal tar mixture enter the coal gas purification device together; 6) After the upgraded coal gas enters the coal gas purification device for processing, part of it is used for industrial production, and the other part is used to generate green electricity through self-generation, which is then supplied to the low-grade pulverized coal electric heating and upgrading device through the regional green electricity grid, thus realizing the recycling of energy.

2. A low-rank pulverized coal electric heating upgrading system for implementing a low-rank pulverized coal electric heating upgrading process as claimed in claim 1, characterized in that: It includes a feeding unit, a low-rank pulverized coal electric heating and upgrading device, a coal-coke mixed heat exchange and screening unit and a coal gas power generation unit; the low-rank pulverized coal electric heating and upgrading device is composed of a device body and a plurality of upgrading chambers and electric heating chambers arranged alternately in the device body, and a plurality of electric heating devices are arranged in the electric heating chamber; a coal inlet is arranged at the top of the upgrading chamber, and a semi-coke outlet is arranged at the bottom; The feeding unit is arranged above the low-grade pulverized coal electric heating and upgrading device, adopts a multi-stage closed feeding structure and is connected to the coal material inlet of the upgrading chamber through multiple discharge ports; a coke discharge bin is arranged at the bottom of the upgrading chamber; the coal-coke mixed heat exchange and screening unit is composed of a coal-coke mixing conveyor, a small-particle coal conveyor, a coal-coke heat exchange bin and a screening device; the coal-coke mixing conveyor is arranged along the arrangement direction of the coke discharge bin, the feeding end of the coal-coke mixing conveyor is connected to the small-particle coal conveyor, and the discharge end of the coal-coke mixing conveyor is connected to the coal-coke heat exchange bin; a screening device is arranged at the discharge port of the coal-coke heat exchange bin; an upgraded coal gas outlet is arranged on the top of the upgrading chamber, and the upgraded coal gas outlet is connected to a coal gas purification device, and a purified coal gas outlet of the coal gas purification device is branched out to connect to a coal gas power generation unit, and the coal gas power generation unit is connected to a regional green power grid; the electric heating device is connected to the power grid through a power line, and the power grid includes a regional green power grid and a public power grid input in parallel, and the regional green power grid and the public power grid are respectively provided with power control valves at the corresponding input ends.

3. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: The loading unit is composed of multiple coal storage bins, multiple buffer coal bins and multiple auxiliary coal bins, and the coal storage bins, buffer coal bins and auxiliary coal bins are all arranged one by one in correspondence with the quality improvement chamber; a coal loading port is arranged on the top of the coal storage bin, and a coal storage bin feeding valve is arranged at the bottom outlet of the coal storage bin; the buffer coal bin has a closed bin body, the feeding port on the top of the buffer coal bin is connected to the bottom outlet of the corresponding coal storage bin, and a buffer coal bin feeding valve is arranged at the bottom outlet of the buffer coal bin; the auxiliary coal bin is a multi-channel structure, the feeding port on the top of the auxiliary coal bin is connected to the bottom outlet of the corresponding buffer coal bin, and the multiple unloading ports of the auxiliary coal bin are connected to the coal material inlet of the corresponding quality improvement chamber, and the multiple unloading ports are evenly distributed along the circumference of the quality improvement chamber.

4. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: The upgrading chamber is a vertical cylindrical structure, with a diverter tower in the middle of the upgrading chamber; the upgrading chamber is composed of a preheating section, a dry distillation section and a coke outlet section from top to bottom, an upgrading gas outlet is provided at the top of the upgrading chamber, and a coke outlet bin is provided at the bottom of the upgrading chamber.

5. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: The electric heating chamber has multiple heating channels evenly arranged in a direction parallel to the upgrading chamber, and openings are provided at the tops of the heating channels; electric heating devices are arranged in one-to-one correspondence in the heating channels; a refractory material layer is provided on the side of the electric heating chamber close to the upgrading chamber; the electric heating chamber located outside the low-grade pulverized coal electric heating upgrading device has an insulating layer on the side close to the device body; the device body consists of an inner wall and an outer steel structure shell.

6. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: The electric heating device is a segmented heating and segmented controlled electric heating device. The preheating section, the dry distillation section and the coke outlet section of the quality upgrading chamber are respectively provided with temperature detection devices. The signal output end of the temperature detection device is connected to the control end of the electric heating device through the control system.

7. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: A gas collecting umbrella is arranged on the upper part of the upgrading chamber; the upgraded gas outlet is connected to the gas purification device through the outlet gas pipeline; an ammonia water spraying device is arranged in the outlet gas pipeline, and a gas temperature detection device is arranged on the outlet gas pipeline downstream of the ammonia water spraying device; an ammonia water flow regulating valve and an ammonia water flow detection device are arranged on the ammonia water conveying pipeline of the ammonia water spraying device; the signal output ends of the gas temperature detection device and the ammonia water flow detection device are respectively connected to the control system, and the control system is also connected to the control end of the ammonia water flow regulating valve.

8. A low-grade pulverized coal electric heating quality upgrading system according to claim 2, characterized in that: An exhaust port is arranged on the top of the coal-coke heat exchange bin and is connected to a gas purification device through a pipeline.

Images