CN113154431A - Powder preparation system and method for high-proportion mixed-burning bituminous coal of steel ball coal mill - Google Patents
Powder preparation system and method for high-proportion mixed-burning bituminous coal of steel ball coal mill Download PDFInfo
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- CN113154431A CN113154431A CN202110389182.6A CN202110389182A CN113154431A CN 113154431 A CN113154431 A CN 113154431A CN 202110389182 A CN202110389182 A CN 202110389182A CN 113154431 A CN113154431 A CN 113154431A
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- 239000003245 coal Substances 0.000 title claims abstract description 424
- 239000000843 powder Substances 0.000 title claims abstract description 193
- 239000002802 bituminous coal Substances 0.000 title claims abstract description 67
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 43
- 239000010959 steel Substances 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 174
- 238000000227 grinding Methods 0.000 claims abstract description 106
- 239000000463 material Substances 0.000 claims abstract description 35
- 238000002485 combustion reaction Methods 0.000 claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 43
- 238000010298 pulverizing process Methods 0.000 claims description 21
- 239000002817 coal dust Substances 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 10
- 239000010419 fine particle Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 7
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- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000010344 co-firing Methods 0.000 claims 1
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/32—Collecting of condensation water; Drainage ; Removing solid particles
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D1/00—Devices using naturally cold air or cold water
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/001—Drying-air generating units, e.g. movable, independent of drying enclosure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/10—Pulverizing
- F23K2201/1003—Processes to make pulverulent fuels
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/10—Pulverizing
- F23K2201/1006—Mills adapted for use with furnaces
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/10—Pulverizing
- F23K2201/103—Pulverizing with hot gas supply
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/20—Drying
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/30—Separating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2203/00—Feeding arrangements
- F23K2203/20—Feeding/conveying devices
- F23K2203/201—Feeding/conveying devices using pneumatic means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Abstract
The embodiment of the invention discloses a powder preparation system and a method for a steel ball coal mill for large-proportion mixed-burning bituminous coal, which comprises the following steps: the coal grinding device who connects gradually, separator, buggy collection device still includes: the air supply device is used for obtaining first cooling air; the air preheating device is used for preheating part of the first cooling air to obtain preheated air, and conveying part of the preheated air to the coal grinding device to dry the mixed coal to obtain dry mixed coal; the cooling device is used for cooling part of the preheated air to obtain second cooling air and conveying part of the second cooling air to the coal grinding device to obtain a cooled and crushed material; the system can obviously improve the combustion performance of pulverized coal and improve the combustion efficiency of a boiler.
Description
Technical Field
The embodiment of the invention relates to the technical field of steel environmental protection, in particular to a powder preparation system and a method for a steel ball coal mill to mix and burn bituminous coal in a large proportion.
Background
The power coal is divided into anthracite, lean coal, soft coal and lignite according to the content of dry ash-free base volatile matter. Bituminous coal is coal with a large coalification degree, is gray black to black in appearance, contains tar-like asphalt substances, and has caking property; the carbon content is 75-90%, the heating value is high, and the flame is long and smokes during combustion; the volatile matter is about 10-40%, the relative density is 1.25-1.35, and the heat value is about 27-37 MJ/kg. The lean coal is the coal with the highest coalification degree, has no caking property, and does not generate a colloid body when being heated; the carbon content is up to 90 percent, the heat productivity is high, the ignition temperature is high, the flame is short during combustion, and the combustion duration is long; general volatile matter>10-20% and the hydrogen content is generally 4-4.5%. Researches show that the bituminous coal after being burned, dried and upgraded can improve the boiler efficiency, reduce the power generation coal consumption and reduce CO2、NOxAnd (5) discharging. With the rapid development of the power industry, the electricity and coal market supply is particularly tense, the coal quality in China is unbalanced, the transportation capacity is limited, and the state requires the power station to try to meet the requirementsThe existing power plants are difficult to ensure that single coal is burnt for a long time due to the burning of inferior coal and the like. In order to guarantee the long-term supply of electric coal and control the fuel cost of a power plant, the combustion of various coal types becomes the inevitable choice of the power plant. However, the bituminous coal is relatively poor, has high moisture and is flammable and explosive, and a powder preparation system has hidden dangers of insufficient drying output, low temperature of powder mixture, high boiler smoke exhaust temperature, safe operation and the like, so that the proportion of blended-burning bituminous coal is limited to be further increased. The coal-fired generating set has a plurality of types of powder-making systems, and the current mature and reliable operation has the powder-making modes such as a middle storage type of a steel ball coal mill, a direct-blowing type of a medium-speed coal mill, a direct-blowing type of a double-inlet and double-outlet steel ball coal mill, a direct-blowing type of a fan coal mill and the like, wherein the adopted steel ball coal mill powder-making system accounts for about 60 percent of the powder-making system of the boiler of the power station in China.
Therefore, how to develop a pulverizing system and a method for a steel ball coal mill with high combustion efficiency of a boiler and mixed-burning bituminous coal in a large proportion becomes a technical problem to be solved urgently.
Disclosure of Invention
The embodiment of the invention aims to provide a powder preparation system and a method for a steel ball coal mill to mix and burn bituminous coal in a large proportion, which can obviously improve the combustion performance of pulverized coal and improve the combustion efficiency of a boiler.
In order to achieve the above object, an embodiment of the present invention provides a coal pulverizing system for a steel ball coal mill for large-proportion mixed-burning bituminous coal, including:
the coal grinding device is used for crushing the mixed coal to obtain a crushed material; the coal grinding device is provided with a first inlet and a first outlet;
the separation device is used for separating the crushed materials to obtain fine-grain coal powder; the separating device is provided with a feeding port and a discharging port, and the feeding port of the separating device is communicated with the first outlet of the coal grinding device;
the pulverized coal collecting device is used for collecting the pulverized coal with the fine particle size, and is provided with a fourth inlet and a fourth outlet, and the fourth inlet of the pulverized coal collecting device is communicated with the discharge hole of the separating device;
the air supply device is used for obtaining first cooling air and comprises an air feeder, a first cooling air pipe and a preheating pipe, and the first cooling air pipe and the preheating pipe are respectively communicated with the air feeder; the blower is communicated with the first inlet of the coal grinding device through the first cooling air pipe;
the air preheating device is used for preheating part of the first cooling air to obtain preheated air and conveying the preheated air to the coal grinding device to dry the mixed coal to obtain dry mixed coal, the air preheating device comprises an air preheater and a hot air pipe, the air preheater is provided with an air inlet and an air outlet, the air inlet of the air preheater is communicated with the air supply device through the preheating pipe, and the air outlet of the air preheater is communicated with the first inlet of the coal grinding device through the hot air pipe;
the cooling device is used for cooling part of the preheated air to obtain second cooling air and conveying part of the second cooling air to the coal grinding device to obtain a cooled and crushed material, the cooling device comprises a cooler, a second cooling air pipe and a third cooling air pipe, the cooler is provided with a fifth inlet and a fifth outlet, the fifth inlet of the cooler is communicated with the air outlet of the air preheating device through the hot air pipe, and the fifth outlet of the cooler is communicated with the first outlet of the coal grinding device through the second cooling air pipe;
the boiler is used for burning the fine-grain coal powder;
the powder feeding device is used for conveying the fine-particle-size coal powder to the boiler, part of the second cooling air is conveyed to the powder feeding device to provide positive pressure, the powder feeding device is provided with a sixth inlet and a sixth outlet, and the sixth inlet of the powder feeding device is communicated with the fifth outlet of the cooling device through a third cooling air pipe; and the sixth outlet of the powder feeding device is communicated with the boiler.
Further, the cooling device further includes:
a steam turbine, a condensed water inlet pipe and a condensed water outlet pipe; the steam turbine is provided with a seventh inlet and a seventh outlet;
the cooler is provided with a condensed water inlet and a condensed water outlet;
the seventh inlet of the steam turbine is communicated with the condensed water outlet of the cooler through the condensed water inlet pipe; and the seventh outlet of the steam turbine is communicated with the condensed water inlet of the cooler through the condensed water outlet pipe.
Further, the powder feeding device includes:
the fourth outlet of the pulverized coal collecting device is communicated with the pulverized coal pipe;
and the powder feeder is provided with a sixth inlet and a sixth outlet, and the sixth outlet of the powder feeder is communicated with the boiler through the pulverized coal pipe.
Further, the separation device includes:
the coarse powder separator is used for separating the crushed materials to obtain coarse-grain-size coal powder; the coarse powder separator is provided with a second inlet and a second outlet, and the second inlet of the coarse powder separator is communicated with the first outlet of the coal mill;
the fine powder separator is used for separating the coarse-particle-size coal powder to obtain fine-particle-size coal powder, and is provided with a third inlet, a third outlet and an exhaust gas outlet, and the third inlet of the fine powder separator is communicated with the second outlet of the coarse powder separator; and the exhaust gas outlet of the fine powder separator is communicated with the coal powder pipe through an exhaust gas pipeline.
Further, the powder preparation system for the steel ball coal mill for the large-proportion mixed-burning bituminous coal further comprises:
the coal feeding device comprises a coal feeder and a raw coal conveying chain, and the coal feeder is communicated with the first inlet of the coal grinding device through the raw coal conveying chain.
The embodiment of the invention provides a powder preparation system method for a steel ball coal mill for large-proportion mixed-burning bituminous coal, which comprises the following steps:
crushing the mixed coal by using the coal grinding device to obtain a crushed material;
separating the crushed materials by using the separation device to obtain fine-particle-size coal powder;
collecting the fine-grain coal dust by using the coal dust collecting device to obtain fine-grain coal dust;
obtaining first cooling air by adopting the air supply device;
preheating the first cooling air by adopting an air preheating device to obtain preheated air, conveying part of the preheated air to the coal grinding device, and drying the mixed coal to obtain dried mixed coal;
cooling part of the preheated air by using a cooling device to obtain second cooling air, and conveying part of the second cooling air to the coal grinding device to cool the crushed materials to obtain cooled crushed materials;
the powder feeding device conveys the fine-grain coal powder to a boiler for combustion, wherein part of the cooling air is conveyed to the powder feeding device to provide positive pressure for the fine-grain coal powder.
Further, the mixed coal comprises the following components in percentage by mass: 50-70% of bituminous coal and 30-50% of lean coal.
Further, the temperature of the first cooling air is 0-40 ℃.
Further, the temperature of the pre-heating air is 380-400 ℃.
Further, the temperature of the second cooling air is 40-50 ℃; the temperature of the cooled crushed material is less than or equal to 80 ℃.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the embodiment of the invention provides a pulverizing system and a pulverizing method for a large-proportion blended bituminous coal of a steel ball coal mill, which comprises the following steps: the coal grinding device is used for crushing the mixed coal to obtain a crushed material; the coal mill is provided with a first inlet and a first outlet; the separation device is used for separating the crushed materials to obtain fine-grain coal powder; the separating device is provided with a feeding port and a discharging port, and the feeding port of the separating device is communicated with the first outlet of the coal grinding device; the pulverized coal collecting device is used for collecting the pulverized coal with the fine particle size, and is provided with a fourth inlet and a fourth outlet, and the fourth inlet of the pulverized coal bin is communicated with the discharge hole of the separating device; the air supply device is used for obtaining first cooling air and comprises an air feeder, a first cooling air pipe and a preheating pipe, and the first cooling air pipe and the preheating pipe are respectively communicated with the air feeder; the blower is communicated with the first inlet of the coal grinding device through the first cooling air pipe; the air preheating device is used for preheating part of the first cooling air to obtain preheated air and conveying the preheated air to the coal grinding device to dry the mixed coal to obtain dry mixed coal, the air preheating device comprises an air preheater and a hot air pipe, the air preheater is provided with an air inlet and an air outlet, the air inlet of the air preheater is communicated with the air supply device through the preheating pipe, and the air outlet of the air preheater is communicated with the first inlet of the coal grinding device through the hot air pipe; the cooling device is used for cooling part of the preheated air to obtain second cooling air and conveying part of the second cooling air to the coal grinding device to obtain a cooled and crushed material, the cooling device comprises a cooler, a second cooling air pipe and a third cooling air pipe, the cooler is provided with a fifth inlet and a fifth outlet, the fifth inlet of the cooler is communicated with the air outlet of the air preheating device through the hot air pipe, and the fifth outlet of the cooler is communicated with the first outlet of the coal grinding device through the second cooling air pipe; the boiler is used for burning the fine-grain coal powder; the powder feeding device is used for conveying the fine-particle-size coal powder to the boiler and conveying part of the second cooling air to the powder feeding device to provide positive pressure, the powder feeding device is provided with a sixth inlet and a sixth outlet, and the sixth inlet of the powder feeding device is communicated with the fifth outlet of the cooling device through a third cooling air pipe; and the sixth outlet of the powder feeding device is communicated with the boiler. The system is additionally provided with a cooling device, and the hot air is cooled and then sent to an outlet of a steel ball coal mill to cool the temperature of the pulverized coal so that the temperature of the crushed material is reduced to be below 80 ℃; the cold air pipeline from the air supply device to the inlet of the coal grinding device is closed, and the hot air quantity is adjusted to dry the raw coal, so that the moisture contained in the bituminous coal is removed in the drying process, the moisture of the raw coal in the coal grinding device is reduced, the deflagration of the pulverized coal can be effectively avoided, and the safety of a coal pulverizing system is remarkably improved; meanwhile, the water content of the bituminous coal does not enter the hearth of the boiler, so that the combustion performance of the pulverized coal can be obviously improved, and the combustion efficiency of the boiler is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a block diagram of a coal pulverizing system for a steel ball coal mill with high-proportion bituminous coal being mixed according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for a coal pulverizing system for a steel ball coal mill with high-proportion bituminous coal being blended according to an embodiment of the present invention;
1-a coal feeding device; 11-a coal feeder; 12-raw coal conveying chain;
2-a coal grinding device; a-a first inlet; b-a first outlet;
3-a separation device; 31-a meal separator; 32-fines separator; c-second inlet (C-feed inlet); d-a second outlet; e-a third inlet; f-a third outlet (F-discharge port), G-a waste gas outlet; 33-a waste gas pipeline;
4-a pulverized coal collecting device; h-a fourth inlet; i-a fourth outlet;
5-an air supply device; 51-a blower; 52-first cooling air duct; 53-a preheating pipe;
6-air preheating device; 61-an air preheater; 62-hot air pipes; j-air inlet; k-air outlet;
7-a cooling device; 71-a cooling machine; 72-a second cooling air duct; 73-a third cooling air duct; l-a fifth inlet; m-a fifth outlet; a P-condensed water inlet; a Q-condensed water outlet; 74-a steam turbine; 75-a condensed water inlet pipe; 76-a condensed water outlet pipe; r-a seventh inlet; s-a seventh outlet;
8-a powder feeding device; 81-powder feeder; 82-pulverized coal pipe; n-a sixth inlet; o-a sixth outlet;
9-boiler.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the embodiments of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that the present embodiments and examples are illustrative of the present invention and are not to be construed as limiting the present invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the invention belong. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, devices and the like used in the examples of the present invention are commercially available or can be prepared by an existing method.
The discovery process of the technical problem of the embodiment of the invention comprises the following steps:
the 220MW coal-fired power generating unit is designed to be used for burning coal which is lean coal in the south of the east, the bituminous coal is mixed and burned in a large proportion in order to meet the requirement of reducing the production cost in operation, and the proportion of the lean coal to the bituminous coal is 1: 2, the steel ball coal mill adopts hot air generated by an air preheater as a drying agent.
Problems in operation:
a large amount of bituminous coal is subjected to a blending combustion test, and the drying requirement of bituminous coal with high moisture can be met by adopting hot air at 350-450 ℃, but the outlet temperature of a coal mill cannot meet the requirement that the air-powder temperature for milling the bituminous coal is controlled below 80 ℃;
if the temperature of hot air can be reduced to 130 ℃ by doping cold air at the inlet of the coal mill, the temperature of air and powder can reach about 80 ℃, so that the effective removal of moisture in the bituminous coal cannot be ensured, the drying output of a powder preparation system is insufficient, the pulverized coal is not easy to ignite, and the combustion is insufficient;
in addition, when a large amount of cold air is mixed into the powder preparation system and the powder feeding system, the consumption of hot air is reduced, the exhaust gas temperature of the boiler is further increased to be more than 180 ℃ in summer, the safe operation of the electric dust remover is seriously influenced, and the mixed cold air is further increased to control the outlet temperature of the coal mill.
Therefore, the existing powder preparation system is not suitable for large-proportion mixed combustion of bituminous coal, and under the condition that the mixed coal contains 50-70% of bituminous coal by mass, the problems of overhigh air-powder temperature, low pulverized coal combustion performance, low boiler combustion efficiency, low safety and the like exist.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
according to an exemplary embodiment of the present invention, there is provided a coal pulverizing system for a steel ball coal mill for high-proportion co-fired bituminous coal, as shown in fig. 1, including:
the coal grinding device 2 is used for crushing the mixed coal to obtain a crushed material; the coal grinding device 2 is provided with a first inlet A and a first outlet B;
the separation device 3 is used for separating the crushed materials to obtain fine-grain coal powder; the separating device 3 is provided with a feeding port and a discharging port, and the feeding port of the separating device 3 is communicated with the first outlet B of the coal grinding device 2;
the pulverized coal collecting device 4 is used for collecting the pulverized coal with the fine particle size, the pulverized coal collecting device 4 is provided with a fourth inlet H and a fourth outlet I, and the fourth inlet H of the pulverized coal collecting device 4 is communicated with the discharge hole of the separating device 3;
the air supply device 5 is used for obtaining first cooling air, the air supply device 5 comprises an air supply device 51, a first cooling air pipe 52 and a preheating pipe 53, and the first cooling air pipe 52 and the preheating pipe 53 are respectively communicated with the air supply device 51; the blower 51 is communicated with the first inlet A of the coal grinding device 2 through the first cooling air pipe 52;
the air preheating device 6 is used for preheating part of the first cooling air to obtain preheated air, and conveying part of the preheated air to the coal grinding device 2 to dry the mixed coal, the air preheating device 6 comprises an air preheater 61 and a hot air pipe 62, the air preheater 61 is provided with an air inlet J and an air outlet K, the air inlet J of the air preheater 61 is communicated with the air supply device 5 through the preheating pipe 53, and the air outlet K of the air preheater 61 is communicated with the first inlet A of the coal grinding device 2 through the hot air pipe 62;
the cooling device 7 is configured to cool a part of the preheated air to obtain second cooling air, and deliver the part of the second cooling air to the coal grinding device 2 to obtain a cooled and crushed material, where the cooling device 7 includes a cooling machine 71, a second cooling air duct 72, and a third cooling air duct 73, the cooling machine 71 is provided with a fifth inlet L and a fifth outlet M, the fifth inlet L of the cooling machine 71 is communicated with the air outlet K of the air preheating device 6 through the hot air duct 62, and the fifth outlet M of the cooling machine 71 is communicated with the first outlet B of the coal grinding device 2 through the second cooling air duct 72;
a boiler 9 for burning the fine particle size pulverized coal;
the powder feeding device 8 is used for conveying the fine-particle-size pulverized coal to the boiler 9 and conveying part of the second cooling air to the powder feeding device 8 to provide positive pressure, the powder feeding device 8 is provided with a sixth inlet N and a sixth outlet O, and the sixth inlet N of the powder feeding device 8 is communicated with a fifth outlet L of the cooling device 7 through the third cooling air pipe 73; the sixth outlet O of the powder feeding device 8 is communicated with the boiler 9.
The working flow of the powder preparation system for the large-proportion blended bituminous coal of the steel ball coal mill provided by the embodiment of the invention is as follows:
1) the mixed coal is sent to a coal grinding device 2, is crushed by the coal grinding device 2, and then enters a separating device 3 from a first outlet B to be separated into coal powder;
2) unqualified coal dust separated by the separating device 3 returns to the coal grinding device 2 for reprocessing, and qualified coal dust separated by the separating device 3 is sent to a coal dust collecting device 4;
3) the outlet cold air of the air supply device 5 is divided into two paths, wherein about 0-70% of the air volume of one path is connected with the inlet of the coal grinding device 2, and about 30-100% of the air volume of the other path is heated to 380-400 ℃ by the air preheating device 6;
4) the hot air heated by the air preheating device 6 is divided into two paths, one path of the hot air with the air volume of 40-60% is connected with the first inlet A of the coal grinding device 2, and the other path of the hot air with the air volume of 40-60% is cooled by the cooling device 7;
5) the cold air cooled by the cooling device 7 is divided into two parts, wherein 50-70% of cooling air is injected into the coal grinding device 2 to cool the coal dust at the first outlet B to below 80 ℃, and 30-50% of cooling air is injected into the coal dust pipe 82 behind the coal dust collecting device 4 to ensure that the coal dust is conveyed to a burner of the boiler 9 to be combusted under positive pressure;
when the device is used, the air supply device 5 is closed to the first cooling air pipe 52 connected with the first inlet A of the coal grinding device 2, and the hot air quantity (connected with the first inlet A of the coal grinding device 2) is adjusted to dry the raw coal, so that the moisture contained in the bituminous coal is removed in the drying process. The reduction of raw coal moisture in the steel ball coal mill can effectively avoid coal dust deflagration, and the safety of a pulverizing system is obviously improved; meanwhile, the water content of the bituminous coal does not enter the hearth of the boiler, so that the combustion performance of the pulverized coal can be obviously improved, and the combustion efficiency of the boiler is improved.
As an alternative embodiment, the cooling device 7 further comprises:
a steam turbine 74, a condensate inlet pipe 75, and a condensate outlet pipe 76; the steam turbine 74 is provided with a seventh inlet R and a seventh outlet S;
the cooler 74 is provided with a condensed water inlet P and a condensed water outlet Q;
the seventh inlet R of the steam turbine 74 is communicated with the condensed water outlet Q of the cooler 71 through the condensed water inlet pipe 75; the seventh outlet S of the steam turbine 74 is communicated with the condensed water inlet P of the cooler 71 through the condensed water outlet pipe 76.
Because the heated condensed water in the cooling machine 71 returns to the regenerative system of the steam turbine 74, partial extraction of the regenerative system of the steam turbine 74 is reduced, the reduced steam returns to the steam turbine 74 to do work, and the heat released by the hot air is recycled through the way. This embodiment can reduce the steam usage of the turbine by 0.4 ton/hour.
As an alternative embodiment, the powder feeding device 8 includes:
the fourth outlet I of the pulverized coal collecting device 4 is communicated with the pulverized coal pipe 82;
and the powder feeder 81 is provided with the sixth inlet N and the sixth outlet O, and the sixth outlet O of the powder feeder 81 is communicated with the boiler 9 through the coal powder pipe 82.
The powder feeder is a new type dilute phase continuous micro-positive pressure pneumatic conveying equipment, its whole course is closed, and it has no dust raising, and can also be indirectly conveyed. The pulverized coal collecting device 4 collects the pulverized coal with the fine particle size, the pulverized coal enters the pulverized coal pipe 82 through the fourth outlet I, and under the positive pressure action of the powder feeder 81, the pulverized coal with the fine particle size in the pulverized coal pipe 82 enters the boiler 9 for combustion.
As an alternative embodiment, the separation device 3 comprises:
a coarse powder separator 31 for separating the crushed material to obtain coarse-particle-size coal powder; the coarse powder separator 31 is provided with a second inlet C and a second outlet D, and the second inlet of the coarse powder separator is communicated with the first outlet of the coal mill;
the fine powder separator 32 is configured to separate the coarse-particle-size coal powder to obtain fine-particle-size coal powder, the fine powder separator 32 is provided with a third inlet E, a third outlet F and a waste gas outlet G, and the third inlet E of the fine powder separator 32 is communicated with the second outlet D of the coarse powder separator 31; the exhaust gas outlet G of the fine powder separator 32 is communicated with the coal powder pipe 82 through an exhaust gas pipeline 33.
In the embodiment, the crushed materials enter the coarse powder separator 31 and the fine powder separator 32 in sequence to obtain qualified coal powder with the size of more than or equal to 0.89mm, and the size of less than or equal to 0.074 mm;
wherein, the unqualified coal powder separated by the fine powder separator 32 returns to the coal grinding device 2 for reprocessing, the qualified coal powder separated by the fine powder separator 32 is sent to the coal powder collecting device 4, and the size of the qualified coal powder (the probability that the coal powder passes through a sieve with the aperture of 90 μm) is controlled to be 78-82%; the unqualified pulverized coal size (the probability that the pulverized coal does not pass through a sieve with the aperture of 90 mu m) is controlled to be 18-22 percent;
as an alternative embodiment, the pulverizing system for high-proportion blended bituminous coal of a steel ball coal mill further comprises:
the coal feeding device 1 comprises a coal feeder 11 and a raw coal conveying chain 12, wherein the coal feeder 11 is communicated with the first inlet of the coal grinding device 2 through the raw coal conveying chain 12.
According to another exemplary embodiment of the present invention, there is provided a method for pulverizing a large-proportion bituminous coal mixed in a steel ball coal mill, which uses the system, as shown in fig. 2, and includes:
s1, crushing the mixed coal by adopting the coal grinding device 2 to obtain a crushed material;
in step S1, the mixed coal includes, in terms of mass fraction: 50-70% of bituminous coal and 30-50% of lean coal. If the mass fraction of the bituminous coal is less than 50%, the adverse effects of high unit price of lean coal, difficult purchase, high operating cost of a power plant and the like exist; if the mass fraction of the bituminous coal is more than 70 percent, the short combustion flame, poor stability, coking and NO are easily causedxAdverse effects such as high emission concentration;
s2, separating the crushed materials by using the separating device 3 to obtain fine-grain coal powder;
in the step S2, the size range of the fine-grain coal powder is 0.074 mm-0.89 mm, and when the grain size is too small, the coal powder flies upward and overflows, so that the effective volume of a coal powder collecting device is reduced, the combustion time is short and other adverse effects are caused; the oversize grain diameter has the adverse effects of increased pressure of a coal powder conveying pipeline, increased power consumption of a powder feeder, difficult combustion of coal powder and the like;
s3, collecting the fine-grain coal powder by the coal powder collecting device 4 to obtain the fine-grain coal powder;
s4, obtaining first cooling air by using the air supply device 5;
in step S4, the temperature of the first cooling air at the outlet of the air supply device 5 is 0 to 40 ℃, which is the cold air temperature range of the conventional air supply device 5;
when the coal mill is used, the air supply device 5 is closed to the first cooling air pipe 52 connected with the first inlet A of the coal grinding device 2, and the first cooling air is directly conveyed to the inlet of the coal grinding device 2, so that the requirement that the temperature of coal dust at the outlet of the coal mill is reduced to be below 80 ℃ is not met, and meanwhile, the supply amount of hot air is reduced.
The first cooling air at the outlet of the air supply device 5 is divided into two paths, wherein about 0-70% of the first cooling air is connected with the inlet of the coal grinding device 2 (the pipeline can be closed when in use), and about 30-100% of the first cooling air is heated to 380-400 ℃ by the air preheating device 6 to obtain preheating air; the air quantity entering the coal grinding device 2 is 0-28 ten thousand cubic meters per hour; the air quantity entering the air preheating device 6 is 12-40 ten thousand cubic meters per hour;
the reason why about 30% to 100% of the first cooling air is delivered to the air preheating device 6 is: when the adding amount of the bituminous coal is less than 60%, the mixed coal can be cooled to be below 80 ℃ by the first cooling air with the maximum temperature of 70%; when the adding amount of the bituminous coal is more than 60%, 100% of the first cooling air is sent to the coal mill, the mixed coal cannot be cooled to be below 80 ℃, so when the coal pulverizer is used, the first cooling air duct is closed, and 100% of the mixed coal is conveyed to the air preheating device 6.
S5, preheating part of the first cooling air by using an air preheating device 6 to obtain preheated air, conveying part of the preheated air to the coal grinding device 2, and drying the mixed coal to obtain dried mixed coal;
in this embodiment, a part of the preheated air obtained by preheating a part of the first cooling air is sent to the coal grinding device 2, and the mixed coal may be dried; if the temperature of the preheating air is less than 380 ℃, the requirement for removing higher moisture in the bituminous coal cannot be met after the bituminous coal is blended and burned in a large proportion, and if the temperature of the preheating air is more than 400 ℃, the mixed coal cannot be cooled to be below 80 ℃ completely by the first cooling air;
the preheating air heated by the air preheating device 6 is divided into two paths, wherein 40% -60% of the air volume of one path is connected with the inlet of the coal grinding device 2, and 40% -60% of the air volume of the other path is cooled by the cooling device 7; the air volume entering the coal grinding device 2 is 12-24 ten thousand cubic meters per hour; the air quantity entering the cooling device 7 is 16-24 ten thousand cubic meters per hour;
when the preheating air is divided into two paths, the air quantity ratio is (4-6): the reasons for (4-6) are: when the mixing burning proportion of the bituminous coal is 60%, 40% of hot air is provided for the mixed coal, so that the drying requirement of the fire coal can be met; when the blending combustion proportion of the bituminous coal is 70%, 60% of hot air is supplied to the mixed coal to meet the drying requirement of the fire coal, so that the hot air amount supplied to the mixed coal is 40% -60%, and the air amount supplied to a cooler is 40% -60%; if the air quantity of the pre-hot air conveyed to the coal grinding device 2 is less than 40%, when the bituminous coal is mixed with the combustion ratio of 60%, the drying degree of the fire coal cannot meet the requirement of a coal grinding machine; if the coal drying degree is higher than 60%, the working pressure of the coal mill is increased, the power consumption and the hot air capacity consumption of the coal mill are improved, and the like;
s6, cooling part of the preheated air by using a cooling device 7 to obtain second cooling air, and conveying part of the second cooling air to the coal grinding device 2 to cool the crushed material to obtain a cooled crushed material;
in step S6, the temperature of the second cooling air cooled by the cooler 71 is 40-50 ℃; if the temperature of the second cooling air is lower than 40 ℃, the adverse effect of increasing the consumption of condensed water is caused; if the temperature of the second cooling air is higher than 50 ℃, the outlet temperature of the coal mill is easily higher than 80 ℃;
the second cooling air cooled by the cooling device 7 is divided into two parts, wherein 50-70% of the cooling air is injected into the coal grinding device 2 to cool the coal dust at the outlet of the coal grinding device to below 80 ℃, and 30-50% of the cooling air is injected into a coal dust pipe 82 behind the coal dust collecting device to ensure that the coal dust is conveyed to a burner of the boiler 9 under positive pressure; the air quantity injected into the coal mill is 12-40 ten thousand cubic meters per hour; the air quantity injected into the pulverized coal bin is 5-12 ten thousand cubic meters per hour;
when the second cooling air is divided into two paths, the air volume ratio is (5-7): the reasons for (3-5) are: when the mixing burning proportion of the bituminous coal is 60%, 50% cold air is provided for the coal mill, so that the requirement that the outlet temperature of the coal mill is lower than 80 ℃ can be met; when the bituminous coal is blended with 70%, 70% of cold air is provided for the coal mill to meet the requirement that the outlet temperature of the coal mill is lower than 80 ℃, so that the cold air quantity supplied to the coal mill is 50% -70%, the air quantity supplied to the coal powder pipe is 30% -50%, and if the air quantity for conveying the pre-hot air to the first outlet B of the coal grinding device 2 is less than 50%, the outlet temperature of the coal mill is higher than 80 ℃ to be adversely affected; if the water content is more than 70 percent, the adverse effect of increasing the consumption of condensed water is caused;
s7, the powder feeding device 8 conveys the fine-particle-size coal powder to a boiler for combustion, wherein part of the cooling air is conveyed to the powder feeding device 2 to provide positive pressure for the fine-particle-size coal powder.
The system and method for pulverizing a high-proportion bituminous coal for a steel ball coal mill according to the present application will be described in detail below with reference to examples, comparative examples and experimental data.
Example 1
1. As shown in fig. 1, a powder making system for a steel ball coal mill for high-proportion blended bituminous coal provided by an embodiment of the present invention includes:
the coal feeding device is used for collecting mixed coal;
the coal grinding device 2 is used for crushing the mixed coal to obtain a crushed material; the coal grinding device 2 is provided with a first inlet A and a first outlet B;
a coarse powder separator 31 for separating the crushed material to obtain coarse-particle-size coal powder; the coarse powder separator is provided with a second inlet and a second outlet, and the second inlet of the coarse powder separator is communicated with the first outlet of the coal mill;
the fine powder separator 32 is used for separating the coarse-particle-size coal powder to obtain fine-particle-size coal powder, and is provided with a third inlet, a third outlet and a waste gas outlet, and the third inlet of the fine powder separator is communicated with the second outlet of the coarse powder separator;
the pulverized coal collecting device 4 is used for collecting the pulverized coal with the fine particle size, the pulverized coal collecting device 4 is provided with a fourth inlet H and a fourth outlet I, and the fourth inlet H of the pulverized coal collecting device 4 is communicated with the discharge hole of the separating device 3;
the air supply device 5 is used for obtaining first cooling air and conveying part of the first cooling air to the coal grinding device 2, the air supply device 5 comprises an air supply blower 51, a first cooling air pipe 52 and a preheating pipe 53, and the first cooling air pipe 52 and the preheating pipe 53 are respectively communicated with the air supply blower 51; the blower 51 is communicated with the first inlet A of the coal grinding device 2 through the first cooling air pipe 52;
the air preheating device 6 is used for preheating part of the first cooling air to obtain preheated air, and conveying part of the preheated air to the coal grinding device 2 to dry the mixed coal, the air preheating device 6 comprises an air preheater 61 and a hot air pipe 62, the air preheater 61 is provided with an air inlet J and an air outlet K, the air inlet J of the air preheater 61 is communicated with the air supply device 5 through the preheating pipe 53, and the air outlet K of the air preheater 61 is communicated with the first inlet A of the coal grinding device 2 through the hot air pipe 62;
the cooling device 7 is configured to cool a part of the preheated air to obtain second cooling air, and deliver the part of the second cooling air to the coal grinding device 2 to obtain a cooled crushed material, where the cooling device 7 includes a cooling machine 71, a second cooling air duct 72, a third cooling air duct 73, a steam turbine 74, a condensed water inlet duct 75, and a condensed water outlet duct 76, the cooling machine 71 is provided with a fifth inlet L, a fifth outlet M, a condensed water inlet P, and a condensed water outlet Q, the fifth inlet L of the cooling machine 71 is communicated with the air outlet K of the air preheating device 6 through the hot air duct 62, and the fifth outlet M of the cooling machine 71 is communicated with the first outlet B of the coal grinding device 2 through the second cooling air duct 72; the seventh inlet R of the steam turbine 74 is communicated with the condensed water outlet Q of the cooler 71 through the condensed water inlet pipe 75; the seventh outlet S of the steam turbine 74 is communicated with the condensed water inlet P of the cooler 71 through the condensed water outlet pipe 76;
a boiler 9 for burning the fine particle size pulverized coal;
the powder feeding device 8 is used for conveying the fine-particle-size pulverized coal to the boiler 9 and conveying part of the second cooling air to the powder feeding device 8 to provide positive pressure, the powder feeding device 8 is provided with a sixth inlet N and a sixth outlet O, and the sixth inlet N of the powder feeding device 8 is communicated with a fifth outlet L of the cooling device 7 through the third cooling air pipe 73; the sixth outlet O of the powder feeding device 8 is communicated with the boiler 9.
2. The proportion of bituminous coal in the mixed coal replacing lean coal is 50%, the requirement that the temperature of an outlet of a coal mill is below 80 ℃ can be met by a method for directly mixing cold air at an outlet of a blower into an inlet of the coal mill, and the method for directly mixing the cold air at the outlet of the blower into an inlet of a coal grinding device 2 comprises the following steps:
1) the mixed coal is conveyed from the coal feeding device 1 to the coal grinding device 2 through the raw coal conveying chain 12, is crushed for 17 minutes by the coal grinding device 2, and is then sequentially connected with the coarse powder separator 31 and the fine powder separator 32 through the coal powder pipeline from the first outlet B to separate the coal powder;
2) returning 8-10 tons/hour of unqualified coal powder to the coal grinding device 2 for reprocessing, and sending 35-37 tons/hour of qualified coal powder to the coal powder collecting device 4 and merging the qualified coal powder with exhaust gas from the top of the fine powder separator 32 into a coal powder pipe 82;
3) 25% of the first cooling air obtained by the blower is heated by the air preheater 61 and is sent to the first inlet A of the coal grinding device 2 through the hot air pipe 62;
4) the remaining 75% of the first cooling air obtained by the blower is directly sent to the first inlet A of the coal grinding device 2 through the first cooling air pipe 52.
5) The pulverized coal temperature of the first outlet B of the coal grinding device 2 is 77-80 ℃, the boiler exhaust gas temperature is 212 ℃, and the boiler energy consumption heat loss is 3.1%.
Example 2
The embodiment of the invention provides a powder preparation system for a large-proportion blended bituminous coal of a steel ball coal mill, which is similar to the embodiment 1, wherein the bituminous coal in mixed coal replaces lean coal and has a proportion of 60%, a method for directly mixing cold air at an outlet of a blower into an inlet of the coal mill cannot meet the requirement that the temperature of the outlet of the coal mill is below 80 ℃, and a method for closing a cold air pipe and cooling hot air is adopted, wherein the method comprises the following steps:
1) the mixed coal is conveyed from the coal feeding device 1 to the coal grinding device 2 through the raw coal conveying chain 12, is crushed for 16 minutes by the coal grinding device 2, and is then sequentially connected with the coarse powder separator 31 and the fine powder separator 32 through the coal powder pipeline from the first outlet B to separate the coal powder;
2) returning 8-10 tons/hour of unqualified coal powder to the coal grinding device 2 for reprocessing, and sending 35-37 tons/hour of qualified coal powder to the coal powder collecting device 4 and collecting exhaust gas from the top of the fine powder separator 32 into a coal powder pipe 82;
3) 100% of the first cooling air obtained by the blower is heated by an air preheater 61 to obtain preheated air;
4) 40% of the air volume of the pre-heated air is sent to the first inlet A of the coal grinding device 2 through the hot air pipe 62, and the rest 60% of the air volume of the blower is cooled through the cooler 71 to obtain second cooling air.
5) And 50% of the second cooling air is injected into the outlet of the coal grinding device 2 through a second cooling air pipe 72, and the rest 50% of the cooling air is conveyed to the combustor of the boiler 9 through a powder feeder 81 under positive pressure to be combusted.
6) The temperature of the pulverized coal at the first outlet B of the coal grinding device 2 is 70 ℃, the temperature of the boiler exhaust gas is 170 ℃, and 3% of the energy consumption of the boiler is utilized by a steam turbine.
Example 3
The embodiment of the invention provides a pulverizing system for a steel ball coal mill to mix and burn bituminous coal in a large proportion, which is similar to the embodiment 1, wherein the bituminous coal in the mixed coal replaces lean coal and the proportion is 70%, and a method for closing a cold air pipe and cooling hot air is adopted, and the method comprises the following steps:
1) the mixed coal is conveyed from the coal feeding device 1 to the coal grinding device 2 through the raw coal conveying chain 12, is crushed for 16 minutes by the coal grinding device 2, and is then sequentially connected with the coarse powder separator 31 and the fine powder separator 32 through the coal powder pipeline from the first outlet B to separate the coal powder;
2) returning 8-10 tons/hour of unqualified coal powder to the coal grinding device 2 for reprocessing, and sending 35-37 tons/hour of qualified coal powder to the coal powder collecting device 4 and merging the qualified coal powder with exhaust gas from the top of the fine powder separator 32 into a coal powder pipe 82;
3) 100% of the first cooling air obtained by the blower is heated by an air preheater 61 to obtain preheated air;
4) 60% of the pre-heated air is delivered to the first inlet A of the coal grinding device 2 through the hot air pipe 62, and the remaining 40% of the air of the blower is cooled through the cooler 71 to obtain second cooling air.
5) 70% of the air quantity of the second cooling air is injected into the outlet of the coal grinding device 2 through the second cooling air pipe 72, and the rest 30% of the air quantity of the second cooling air is conveyed to the combustor of the boiler 9 for combustion through the powder feeder 81 under positive pressure.
6) The temperature of the pulverized coal at the outlet of the coal grinding device 2 is 70 ℃, the temperature of the boiler exhaust gas is 170 ℃, and 3% of the energy consumption of the boiler is utilized by a steam turbine.
Comparative example 1
The method for directly mixing the bituminous coal in the mixed coal instead of the lean coal by using cold air at the outlet of the blower at a ratio of 51% into the inlet of the coal grinding device 2 comprises the following steps:
1) the mixed coal is conveyed from the coal feeding device 1 to the coal grinding device 2 through the raw coal conveying chain 12, is crushed for 17 minutes by the coal grinding device 2, and is then sequentially connected with the coarse powder separator 31 and the fine powder separator 32 through the coal powder pipeline from the first outlet B to separate the coal powder;
2) returning 8-10 tons/hour of unqualified coal powder to the coal grinding device 2 for reprocessing, and sending 35-37 tons/hour of qualified coal powder to the coal powder collecting device 4 and merging the qualified coal powder with exhaust gas from the top of the fine powder separator 32 into a coal powder pipe 82;
3) 30% of the first cooling air obtained by the blower is heated by the air preheater 61 and sent to the first inlet A of the coal grinding device 2 through the hot air pipe 62;
4) the remaining 70% of the first cooling air obtained by the blower is directly sent to the first inlet A of the coal grinding device 2 through the first cooling air pipe 52.
5) The pulverized coal temperature of the first outlet B of the coal grinding device 2 is 80-85 ℃, the boiler exhaust gas temperature is 210 ℃, and the boiler energy consumption heat loss is 3%.
Experimental example 1
The water quality comparison before and after the treatment of the above examples 1 to 3 was calculated as shown in Table 1 below.
TABLE 1
From the data in table 1, it can be seen that:
in the comparative example 1, cold air at the outlet of the air feeder is directly mixed into the inlet of the coal grinding device, so that the temperature of hot air at the inlet of the coal grinding device is reduced due to excessive cold air, and the effective removal of moisture in the bituminous coal cannot be guaranteed; meanwhile, the consumption of hot air is reduced, so that the exhaust gas temperature of the boiler is further increased;
in the embodiments 1 to 3, the process requirements of effectively removing moisture of the blended bituminous coal at the inlet of the steel ball coal mill and controlling the outlet temperature to be below 80 ℃ are met, the heat energy efficiency of hot air can be improved by 3%, the exhaust gas temperature of a boiler is reduced by more than 20 ℃, the system operation safety is ensured, and good social benefits and economic benefits are achieved.
Therefore, compared with the traditional powder making system, the powder making system for the large-proportion mixed-burning bituminous coal of the steel ball coal mill provided by the embodiment of the invention has the following beneficial effects:
1. according to the embodiment of the invention, the bituminous coal with high water content is completely dried at the inlet of the steel ball coal mill by using hot air, so that the hot air use efficiency is obviously improved.
2. The embodiment of the invention aims at the condition that the capacities of the original blower and the original air preheater are set, the cold air pipeline (the first cooling air pipe 51) at the inlet of the steel ball coal mill is closed, the generation amount of hot air can be increased, the smoke exhaust temperature of the boiler can be reduced, and the thermal efficiency of the boiler can be improved.
3. According to the embodiment of the invention, the cooler 71 is additionally arranged on the main pipe of the hot air pipe 62, the hot air is cooled and then is sent to the outlet of the steel ball coal mill to cool the temperature of the coal powder, the heated condensed water returns to the heat regenerative system of the steam turbine, so that partial steam extraction of the heat regenerative system is reduced, the reduced steam returns to the steam turbine to do work, and the heat released by the hot air is recycled through the way.
4. The embodiment of the invention has simple process, small transformation investment and short construction period.
5. The embodiment of the invention overcomes the technical problems in the prior art, meets the process requirements of effectively removing the moisture of the bituminous coal blended and burned at the inlet of the steel ball coal mill and controlling the outlet temperature below 80 ℃, can also improve the heat energy efficiency of hot air by 3 percent, reduces the exhaust temperature of a boiler by more than 20 ℃, ensures the safe operation of a system, and has good social benefit and economic benefit.
Finally, it should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention without departing from the spirit or scope of the embodiments of the invention. Thus, if such modifications and variations of the embodiments of the present invention fall within the scope of the claims of the embodiments of the present invention and their equivalents, the embodiments of the present invention are also intended to encompass such modifications and variations.
Claims (10)
1. A powder process system for a steel ball coal mill to mix and burn bituminous coal in a large proportion is characterized by comprising the following steps:
the coal grinding device is used for crushing the mixed coal to obtain a crushed material; the coal grinding device is provided with a first inlet and a first outlet;
the separation device is used for separating the crushed materials to obtain fine-grain coal powder; the separating device is provided with a feeding port and a discharging port, and the feeding port of the separating device is communicated with the first outlet of the coal grinding device;
the pulverized coal collecting device is used for collecting the pulverized coal with the fine particle size, and is provided with a fourth inlet and a fourth outlet, and the fourth inlet of the pulverized coal collecting device is communicated with the discharge hole of the separating device;
the air supply device is used for obtaining first cooling air and comprises an air feeder, a first cooling air pipe and a preheating pipe, and the first cooling air pipe and the preheating pipe are respectively communicated with the air feeder; the blower is communicated with the first inlet of the coal grinding device through the first cooling air pipe;
the air preheating device is used for preheating part of the first cooling air to obtain preheated air and conveying the part of the preheated air to the coal grinding device to dry the mixed coal, the air preheating device comprises an air preheater and a hot air pipe, the air preheater is provided with an air inlet and an air outlet, the air inlet of the air preheater is communicated with the air supply device through the preheating pipe, and the air outlet of the air preheater is communicated with the first inlet of the coal grinding device through the hot air pipe;
the cooling device is used for cooling part of the preheated air to obtain second cooling air and conveying part of the second cooling air to the coal grinding device to obtain a cooled and crushed material, the cooling device comprises a cooler, a second cooling air pipe and a third cooling air pipe, the cooler is provided with a fifth inlet and a fifth outlet, the fifth inlet of the cooler is communicated with the air outlet of the air preheating device through the hot air pipe, and the fifth outlet of the cooler is communicated with the first outlet of the coal grinding device through the second cooling air pipe;
the boiler is used for burning the fine-grain coal powder;
the powder feeding device is used for conveying the fine-particle-size coal powder to the boiler and conveying part of the second cooling air to the powder feeding device to provide positive pressure, the powder feeding device is provided with a sixth inlet and a sixth outlet, and the sixth inlet of the powder feeding device is communicated with the fifth outlet of the cooling device through a third cooling air pipe; and the sixth outlet of the powder feeding device is communicated with the boiler.
2. The coal pulverizing system for steel ball coal mill high proportion co-fired bituminous coal as claimed in claim 1, wherein said cooling means further comprises:
a steam turbine, a condensed water inlet pipe and a condensed water outlet pipe; the steam turbine is provided with a seventh inlet and a seventh outlet;
the cooler is provided with a condensed water inlet and a condensed water outlet;
the seventh inlet of the steam turbine is communicated with the condensed water outlet of the cooler through the condensed water inlet pipe; and the seventh outlet of the steam turbine is communicated with the condensed water inlet of the cooler through the condensed water outlet pipe.
3. The coal pulverizing system for the steel ball coal mill for the large-proportion co-fired bituminous coal as claimed in claim 1, wherein the powder feeding device comprises:
the fourth outlet of the pulverized coal collecting device is communicated with the pulverized coal pipe;
and the powder feeder is provided with a sixth inlet and a sixth outlet, and the sixth outlet of the powder feeder is communicated with the boiler through the pulverized coal pipe.
4. A coal pulverizing system for high-proportion co-fired bituminous coal for steel ball coal mills as claimed in claim 3, wherein said separation means comprises:
the coarse powder separator is used for separating the crushed materials to obtain coarse-grain-size coal powder; the coarse powder separator is provided with a second inlet and a second outlet, and the second inlet of the coarse powder separator is communicated with the first outlet of the coal mill;
the fine powder separator is used for separating the coarse-particle-size coal powder to obtain fine-particle-size coal powder, and is provided with a third inlet, a third outlet and an exhaust gas outlet, and the third inlet of the fine powder separator is communicated with the second outlet of the coarse powder separator; and the exhaust gas outlet of the fine powder separator is communicated with the coal powder pipe through an exhaust gas pipeline.
5. The coal pulverizing system for steel ball coal mill high proportion blended coal as claimed in claim 1, further comprising:
the coal feeding device comprises a coal feeder and a raw coal conveying chain, and the coal feeder is communicated with the first inlet of the coal grinding device through the raw coal conveying chain.
6. A method for pulverizing a high-rank, coal-blended coal for a steel ball coal mill using the system of any one of claims 1 to 5, the method comprising:
crushing the mixed coal by using the coal grinding device to obtain a crushed material;
separating the crushed materials by using the separation device to obtain fine-particle-size coal powder;
collecting the fine-grain coal dust by using the coal dust collecting device to obtain fine-grain coal dust;
obtaining first cooling air by adopting the air supply device;
preheating the first cooling air by using the air preheating device to obtain preheated air, conveying part of the preheated air to the coal grinding device, and drying the mixed coal;
cooling part of the preheated air by using the cooling device to obtain second cooling air, and conveying part of the second cooling air to the coal grinding device to cool the crushed materials to obtain cooled crushed materials;
and conveying the fine-grain coal powder to a boiler for combustion by adopting the powder feeding device, wherein part of the cooling air is conveyed to the powder feeding device to provide positive pressure for the fine-grain coal powder.
7. The method for manufacturing a coal pulverizing system for a steel ball coal mill with high-proportion bituminous coal as claimed in claim 5, wherein the mixed coal comprises, by mass fraction: 50-70% of bituminous coal and 30-50% of lean coal.
8. The method for manufacturing a coal pulverizing system for a steel ball coal mill with high-proportion bituminous coal being mixed according to claim 5, wherein the temperature of the first cooling air is 0-40 ℃.
9. The method for preparing powder by using high-proportion co-fired bituminous coal for the steel ball coal mill as claimed in claim 5, wherein the temperature of the pre-heating air is 380-400 ℃.
10. The method for preparing a coal pulverizing system by using a steel ball coal mill and high-proportion co-firing bituminous coal as claimed in claim 5, wherein the temperature of the secondary cooling air is 40-50 ℃; the temperature of the cooled crushed material is less than or equal to 80 ℃.
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