Coal pyrolysis high-temperature coal gas oil-dust separation equipment and method

Abstract

The invention provides oil-dust separation equipment and method for coal pyrolysis high-temperature coal gas. A high-temperature oil-gas separation system, a dust centralized storage system and a nitrogen recovery system which are sequentially connected with a coal pyrolysis kiln are adopted for carrying out oil-gas and dust separation on the coal pyrolysis high-temperature coal gas generated by the coal pyrolysis kiln. According to the invention, a high-temperature constant-temperature environment required by efficient separation of oil gas and dust is ensured, and the quality and the yield of recovered tar are improved; meanwhile, in a high-temperature environment, the dust collected by the high-temperature oil-gas separation system is timely conveyed to the purified coke powder concentration bin for storage through the pneumatic conveying device, so that the dust containing a small amount of tar gas is prevented from being condensed and coked in an ash hopper and a conveying pipeline, and the problems of failure of a filtering system and blockage of equipment pipelines are solved; and the high-temperature nitrogen in the pneumatic conveying device can be pressurized and recycled through the nitrogen recycling system, so that the energy consumption for heating the nitrogen and the operation cost of the nitrogen generation station are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of precast track slab base construction, and particularly to a coal pyrolysis high-temperature coal gas oil dust separation device and method. Background Art

[0002] Among China's coal resources, the output of low-rank coal has exceeded 50%, and the proportion is increasing year by year. Low-rank coal has a short coal formation time, many side chains, and high volatile matter. These characteristics determine that high-value-added oil and gas can be extracted from low-rank coal through atmospheric pressure, medium and low-temperature pyrolysis technology, and the high-value-added and clean conversion of low-rank coal can be achieved efficiently and economically under mild conditions.

[0003] In the low-rank coal pyrolysis process, it is necessary to timely remove coke powder in high-temperature oil and gas in the high-temperature section after the pyrolysis furnace and before tar condensation. If the coke powder in high-temperature oil and gas cannot be filtered efficiently and in a timely manner, it will cause pipeline blockage, wear of key equipment, and deterioration of the recovered tar quality in the subsequent tar recovery process.

[0004] Traditional low-rank coal medium and low-temperature pyrolysis furnace types are mainly vertical furnaces, and the coal raw materials used are lump coal with a particle size of 30 - 80 mm, which cannot process low-rank crushed coal and fine coal (less than 10 mm) with small particle sizes. The new low-rank coal pyrolysis technology usually uses pulverized coal and crushed coal with large output, small particle sizes, and low prices as raw materials for atmospheric pressure medium and low-temperature pyrolysis. This technology couples raw coal preheating, high-temperature oil and gas dust removal, efficient tar recovery, dry coke quenching and other links, and has many advantages such as large single furnace scale, low investment, small pollution, low emissions, and high energy efficiency. However, in the process of engineering this technology, there are relatively large problems with high-temperature dusty oil and gas dust removal technology, which restricts its large-scale popularization and use.

[0005] The dusty oil and gas generated during low-rank coal pyrolysis has a high temperature and is prone to phase change. When the temperature changes and tar cools and precipitates, it will entrain a large amount of dust, which not only affects the quality of tar products, but also makes the fluidity of tar worse, resulting in blockage of equipment and pipelines and inability to achieve long-term operation. Dusty oil and gas dust removal from pulverized coal pyrolysis has become a key link restricting the development of low-rank coal medium and low-temperature pyrolysis technology.

[0006] Existing pulverized coal pyrolysis high-temperature oil and gas dust removal technologies have the following bottlenecks but are not limited to: (1) The dust collector needs to have good heating and heat preservation effects to avoid condensation of pyrolysis gas in the dust collector due to temperature changes; (2) The pyrolysis gas contains large molecular aromatic substances that are easy to condense and adhere, which easily causes blockage of the dust collector; (3) The residence time of pyrolysis gas in the dust collector should be short and the dust removal speed should be fast to avoid secondary pyrolysis of pyrolysis gas in the dust collector and reduce oil production; (4) The coke dust collected by the dust collector should be transported in a timely manner to prevent the appearance of dusty tar due to condensation of high-temperature oil and gas, which adheres to the conveying pipeline. Summary of the Invention

[0007] The object of the present invention is to provide a coal pyrolysis high-temperature coal gas oil-dust separation device and method to solve the deficiencies of the above-mentioned prior art.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A coal pyrolysis high-temperature coal gas oil-dust separation device, comprising:

[0010] A high-temperature oil-gas separation system, which includes a pre-processor for pre-separating oil-gas and dust from the coal pyrolysis high-temperature coal gas and a fine filter for further filtering and removing dust from the pre-separated oil-gas. Dust collection devices are provided for both the pre-processor and the fine filter;

[0011] A dust centralized storage system, which includes a purified coke powder centralized bin and a pneumatic conveying device that uses high-pressure nitrogen positive pressure dense phase method to convey the dust in the dust collection device to the purified coke powder centralized bin;

[0012] And a nitrogen recovery system, which includes a nitrogen recovery filter provided at the top of the purified coke powder centralized bin, and a dirty nitrogen gas storage tank, an induced draft fan, a nitrogen filter, a clean nitrogen gas storage tank, a nitrogen compressor, and a clean nitrogen gas storage tank connected to the nitrogen recovery filter in sequence;

[0013] The high-temperature oil-gas separation system and the dust centralized storage system are always in a constant temperature or continuously rising temperature state during operation.

[0014] Further, the pre-processor includes a pre-separation bin, a coarse filter provided in the pre-separation bin, and a conical ash hopper I as a dust collection device connected to the lower end of the pre-separation bin;

[0015] The fine filter includes a fine filtration bin, a metal filter element filter provided in the fine filtration bin, and a conical ash hopper II as a dust collection device connected to the lower end of the fine filtration bin;

[0016] An air outlet is provided at the top of the coarse filter, an air inlet is provided at the bottom end of the fine filtration bin and is communicated with the air outlet through a first pipeline, and an exhaust port for clean high-temperature oil-gas is provided at the upper end of the fine filtration bin;

[0017] The coarse filter can have a filtration efficiency of 80% for dust with a particle size above 10μm, and the dust content in the purified gas after fine filtration by the metal filter element filter is ≤5mg / m 3 ;

[0018] The nitrogen pressure conveyed by the pneumatic conveying device is 0.5MPa;

[0019] The bottoms of the conical ash hoppers I and II are provided with ash outlets and are connected to the pneumatic conveying device through a high-temperature sealed scraper conveyor and a second pipeline. The pneumatic conveying device is connected to the purified coke powder centralized bin through a third pipeline.

[0020] Furthermore, heat-insulating jackets are provided on the outer surfaces of the pre-processor, fine filter, pneumatic conveying device, purified coke powder centralized bin, as well as on the first pipeline, second pipeline, and third pipeline.

[0021] The heat-insulating jacket includes a hollow layer connected to a hot blast stove and a heat-insulating layer covering the outer surface of the hollow layer.

[0022] Furthermore, the purified coke powder centralized bin includes a shell and a conical ash hopper III connected to the lower end of the shell. An opening communicating with the high-temperature pneumatic conveying device is provided at the upper end of the shell.

[0023] A method for separating oil and dust from high-temperature coal gas during coal pyrolysis is realized based on the above-mentioned equipment for separating oil and dust from high-temperature coal gas during coal pyrolysis, and includes the following steps:

[0024] S1. Continuously convey hot air to all the heat-insulating interlayers through a hot blast stove to keep the devices and pipelines where the heat-insulating interlayers are located at a constant temperature or in a heating state.

[0025] S2. In the pre-processor, preliminarily separate the oil and gas and dust in the high-temperature coal gas generated by the coal pyrolysis kiln through a coarse filter. The coarsely filtered dust is collected into the conical ash hopper I, and the oil and gas containing fine particulate dust are conveyed to the metal filter element filter.

[0026] S3. In the metal filter element filter, further filter the oil and gas containing fine particulate dust through a fine filter. The finely filtered dust is collected into the conical ash hopper II, and the clean high-temperature oil and gas are discharged from the top of the metal filter element filter.

[0027] S4. In real time, collect the dust in the conical ash hopper I and conical ash hopper II into the pneumatic conveying device through a high-temperature sealed scraper conveyor, and convey it to the purified coke powder centralized bin in a positive-pressure dense-phase manner using high-pressure nitrogen. The high-temperature nitrogen fed into the purified coke powder centralized bin enters the dirty nitrogen storage tank after being preliminarily filtered by a nitrogen recovery filter.

[0028] S5. Convey the dirty nitrogen in the dirty nitrogen storage tank to a nitrogen filter through a induced draft fan for fine filtration to obtain clean nitrogen and store it in a clean nitrogen storage tank.

[0029] S6. Pressurize the clean nitrogen in the clean nitrogen storage tank to 0.5 MPa through a nitrogen compressor and recycle it to the clean nitrogen storage tank for reuse.

[0030] Further, the temperature in the constant temperature state is 500°C - 550°C, and the minimum temperature in the temperature rising state is not less than 500°C.

[0031] As can be seen from the above technical solutions, the present invention ensures the high-temperature constant temperature environment required for efficient separation of oil gas and dust, improves the quality and output of the recovered tar; at the same time, in the high-temperature environment, the dust collected by the high-temperature oil gas separation system is timely transported to the purified coke powder centralized storage bin through the pneumatic conveying device, avoiding condensation and coking of the dust containing a small amount of coke oil gas in the ash hopper and the conveying pipeline, and solving the problems of filter system failure and equipment pipeline blockage; and through the nitrogen recovery system, the high-temperature nitrogen in the pneumatic conveying device can be pressurized and recycled, greatly reducing the energy consumption for heating nitrogen and the operating cost of the nitrogen production station. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the overall structural schematic diagram of the high-temperature coal pyrolysis gas oil and dust separation equipment of the present invention;

[0033] In the figure: 1. Pretreatment device; 2. Fine filter; 3. Dust collection device; 4. Purified coke powder centralized storage bin; 5. Pneumatic conveying device; 6. Nitrogen recovery filter; 7. Waste nitrogen gas storage tank; 8. Induced draft fan; 9. Nitrogen filter; 10. Clean nitrogen gas storage tank; 11. Nitrogen compressor; 12. Clean nitrogen gas storage tank; 13. High-temperature sealed scraper conveyor; 14. Heat preservation jacket. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] As Figure 1 shown, the high-temperature coal pyrolysis gas oil and dust separation equipment includes a high-temperature oil gas separation system, a dust centralized storage system, and a nitrogen recovery system that are sequentially connected to the coal pyrolysis kiln. Specifically, the high-temperature oil gas separation system includes a pretreatment device 1 for pre-separating oil gas and dust from the high-temperature coal pyrolysis gas and a fine filter 2 for further filtering and removing dust from the pre-separated oil gas. The pretreatment device 1 and the fine filter 2 are both provided with a dust collection device 3; the dust centralized storage system includes a purified coke powder centralized storage bin 4 and a pneumatic conveying device 5 that transports the dust in the dust collection device 3 to the purified coke powder centralized storage bin 4 in a positive pressure dense phase manner using high-pressure nitrogen; the nitrogen recovery system includes a nitrogen recovery filter 6 provided at the top of the purified coke powder centralized storage bin 4 and a waste nitrogen gas storage tank 7, an induced draft fan 8, a nitrogen filter 9, a clean nitrogen gas storage tank 10, a nitrogen compressor 11, and a clean nitrogen gas storage tank 12 that are sequentially connected to the nitrogen recovery filter 6; the high-temperature oil gas separation system and the dust centralized storage system are always in a constant temperature or continuously rising temperature state during operation to improve the quality and output of the recovered tar.

[0036] The pre-processor 1 in this preferred embodiment includes a pre-separation bin, a coarse filter (such as a cyclone dust collector) disposed in the pre-separation bin, and a conical ash hopper 1 serving as a dust collection device 3 connected to the lower end of the pre-separation bin; the fine filter 2 includes a fine filtration bin, a metal filter element filter disposed in the fine filtration bin, and a conical ash hopper 2 serving as a dust collection device 3 connected to the lower end of the fine filtration bin; the coarse filter can have a filtration efficiency of 80% for dust with a particle size above 10 μm, and the dust content in the purified gas after fine filtration by the metal filter element filter is ≤5 mg / m 3 ; an air outlet is provided at the top of the coarse filter, an air inlet is provided at the bottom end of the fine filtration bin and is communicated with the air outlet through a first pipeline, and an exhaust port for clean high-temperature oil and gas is provided at the upper end of the fine filtration bin; ash outlets are provided at the bottom ends of the conical ash hopper 1 and the conical ash hopper 2 and are communicated with a pneumatic conveying device 5 through a high-temperature sealed scraper conveyor 13 and a second pipeline, the pneumatic conveying device is communicated with a purified coke powder centralized bin through a third pipeline, and the pneumatic conveying device 5 is communicated with a purified coke powder centralized bin 4 through a third pipeline.

[0037] The pneumatic conveying device 5 in this preferred embodiment adopts a dense-phase positive-pressure pneumatic conveying system, and the nitrogen pressure for pneumatic conveying is 0.5 MPa; further, the purified coke powder centralized bin 4 includes a housing and a conical ash hopper 3 connected to the lower end of the housing, and an opening communicated with the pneumatic conveying device 5 is provided at the upper end of the housing.

[0038] During the actual coke powder collection process, it is inevitable that a very small amount of coke oil gas is mixed. As the temperature of the coke oil gas decreases, it condenses and precipitates. After the precipitated tar is mixed with the coke powder, the viscosity becomes larger, which is not conducive to the pneumatic conveying of the coke powder. Therefore, in order to ensure that the high-temperature oil and gas separation system and the dust centralized storage system are always in a constant temperature or continuously rising temperature state during operation, heat preservation jackets 14 are provided on the outer surfaces of the pre-processor 1, the fine filter 2, the pneumatic conveying device 5, the purified coke powder centralized bin 4, as well as on the first pipeline, the second pipeline, and the third pipeline; the heat preservation jacket 14 includes a hollow layer connected to a hot blast stove and a heat preservation layer covering the outer surface of the hollow layer. The hot air generated by the hot blast stove enters the hollow layer and cooperates with the heat preservation layer to keep the high-temperature oil and gas separation system and the dust centralized storage system in a constant temperature or continuously rising temperature state during operation.

[0039] The oil and gas and dust in the high-temperature constant temperature environment can be efficiently separated, improving the quality and output of the recovered tar; the pneumatic conveying device in the high-temperature environment timely conveys the collected dust to the high-temperature and high-pressure nitrogen purified ash centralized bin 4, avoiding the condensation and coking of the dust containing a small amount of coke oil gas in the dust collector ash hopper and the conveying pipeline, and effectively solving the problems of filter system failure and equipment pipeline blockage.

[0040] A method for separating oil dust from high-temperature coal gas during coal pyrolysis, which is realized based on the above-mentioned equipment for separating oil dust from high-temperature coal gas during coal pyrolysis, and includes the following steps:

[0041] S1. Continuously convey hot air to all heat preservation interlayers through a hot blast stove, so that the devices and pipelines where the heat preservation interlayers are located are kept at a constant temperature or in a heating state;

[0042] In specific operations, the temperature of the constant temperature state is 500°C - 550°C, and the minimum temperature of the heating state is not less than 500°C.

[0043] S2. In the pre-processor, the high-temperature coal gas generated by the coal pyrolysis kiln is preliminarily separated from oil and dust through a coarse filter. The coarse particulate dust filtered out is collected into a conical ash hopper 1, and the oil gas containing fine particulate dust is transported to a metal filter element filter. It can have a filtration efficiency of 80% for dust with a particle size of more than 10μm.

[0044] S3. In the metal filter element filter, the oil gas containing fine particulate dust is further filtered from oil and dust through a fine filter. The fine particulate dust filtered out is collected into a conical ash hopper 2, and the clean high-temperature oil gas is discharged from the top of the metal filter element filter. The dust content in the purified gas after fine filtration by the metal filter element filter is ≤5mg / m 3 .

[0045] S4. In real time, the dust in the conical ash hopper 1 and the conical ash hopper 2 is collected into a pneumatic conveying device through a high-temperature sealed scraper conveyor, and is transported to a purified coke powder centralized bin in a positive pressure dense phase manner using high-pressure nitrogen. The high-temperature nitrogen sent into the purified coke powder centralized bin enters the dirty nitrogen gas storage tank after preliminary filtration by a nitrogen recovery filter;

[0046] S5. The dirty nitrogen in the dirty nitrogen gas storage tank is transported to a nitrogen filter through an induced draft fan for fine filtration, and clean nitrogen is obtained and stored in a clean nitrogen gas storage tank;

[0047] S6. The clean nitrogen in the clean nitrogen gas storage tank is pressurized to 0.5MPa by a nitrogen compressor and recycled to a clean nitrogen gas storage tank for reuse; greatly reducing the energy consumption for heating nitrogen and the operating cost of the nitrogen production station.

[0048] The above-mentioned embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A coal pyrolysis high temperature coal gas oil dust separation device, characterized in that: Including connected in sequence with the coal pyrolysis kiln: A high-temperature oil-gas separation system, the high-temperature oil-gas separation system comprising a pre-processor for pre-separating oil, gas and dust from high-temperature coal gas from coal pyrolysis, and a fine filter for further filtering and removing dust from the pre-separated oil and gas, the pre-processor and the fine filter both being provided with a dust collection device; A dust centralized storage system, the dust centralized storage system comprising a purified coke powder centralized bin and a pneumatic conveying device for conveying dust in the dust collection device to the purified coke powder centralized bin by using a high-pressure nitrogen positive pressure dense phase method; and a nitrogen recovery system, the nitrogen recovery system comprising a nitrogen recovery filter disposed at the top of the purified coke powder concentration bin, and a dirty nitrogen gas storage cabinet, an induced draft fan, a nitrogen filter, a clean nitrogen gas storage cabinet, a nitrogen compressor, and a clean nitrogen gas storage tank sequentially connected to the nitrogen recovery filter; The high-temperature oil-gas separation system and the dust centralized storage system are always in a constant temperature or continuously heated state during operation.

2. The coal pyrolysis high temperature gas oil dust separation equipment according to claim 1, characterized in that: The pre-processor comprises a pre-separation bin, a coarse filter arranged in the pre-separation bin, and a conical ash hopper connected to the lower end of the pre-separation bin as a dust collection device; The fine filter comprises a fine filter bin, a metal filter element filter arranged in the fine filter bin, and a conical ash hopper 2 connected to the lower end of the fine filter bin as a dust collection device; The top of the coarse filter is provided with an air outlet, the bottom of the fine filter bin is provided with an air inlet and is connected to the air outlet through a first pipeline, and the upper end of the fine filter bin is provided with an exhaust port for clean high-temperature oil and gas; The coarse filter can have a filtration efficiency of 80% for dust with a particle size of 10 μm or more, and the dust content in the purified gas after fine filtration by the metal filter element is ≤5 mg / m 3 ; The nitrogen pressure delivered by the pneumatic conveying device is 0.5MPa; The bottom ends of the conical ash hopper 1 and the conical ash hopper 2 are provided with ash outlets and are connected to the pneumatic conveying device through a high-temperature closed scraper and a second pipeline. The pneumatic conveying device is connected to the purified coke powder concentration bin through a third pipeline.

3. The coal pyrolysis high temperature gas oil dust separation equipment according to claim 2, characterized in that: The outer surfaces of the pre-processor, the fine filter, the pneumatic conveying device, the purified coke powder concentration bin, and the first pipeline, the second pipeline, and the third pipeline are all provided with insulation jackets; The heat-insulating jacket comprises a hollow layer connected to a hot air furnace and a heat-insulating layer covering the outer surface of the hollow layer.

4. The coal pyrolysis high temperature gas oil dust separation equipment according to claim 2, characterized in that: The purified coke powder concentration bin comprises a shell and a conical ash hopper three connected to the lower end of the shell, and an opening connected to the high-temperature pneumatic conveying device is provided at the upper end of the shell.

5. A method for separating oil and dust from high-temperature coal gas from coal pyrolysis, which is realized based on the equipment for separating oil and dust from high-temperature coal gas from coal pyrolysis as described in any one of claims 1 to 4, and is characterized in that: The following steps are involved: S1. Continuously deliver hot air to all insulation interlayers through the hot air furnace to keep the devices and pipelines where the insulation interlayers are located at a constant temperature or a heating state; S2. In the pre-processor, the high-temperature coal gas generated by the coal pyrolysis kiln is passed through a coarse filter to perform preliminary separation of oil, gas and dust. The coarse dust particles filtered out are collected in a conical ash hopper, and the oil and gas containing fine dust particles are transported to a metal filter element filter. S3. In the metal filter element filter, the oil and gas containing fine dust particles are further filtered through the fine filter. The filtered fine dust particles are collected in the conical ash hopper 2, and the clean high-temperature oil and gas are discharged from the top of the metal filter element filter; S4, collecting the dust in the conical ash hopper 1 and the conical ash hopper 2 in real time through a high-temperature closed scraper and entering the pneumatic conveying device, and conveying it to the purified coke powder concentration bin in a positive pressure dense phase manner using high-pressure nitrogen. The high-temperature nitrogen sent to the purified coke powder concentration bin is initially filtered by a nitrogen recovery filter and then enters the dirty nitrogen gas storage cabinet; S5. The dirty nitrogen in the dirty nitrogen gas storage cabinet is transported to the nitrogen filter through the induced draft fan for fine filtration to obtain clean nitrogen and store it in the clean nitrogen gas storage cabinet; S6. Pressurize the clean nitrogen in the clean nitrogen storage cabinet to 0.5MPa through a nitrogen compressor and recover it into a clean nitrogen storage tank for recycling.

6. A method for separating oil dust from high-temperature coal gas from coal pyrolysis according to claim 5, characterized in that: The temperature in the constant temperature state is 500°C-550°C, and the lowest temperature in the heating state is not less than 500°C.

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