CN114353059B - Extremely narrow screening particle diameter pulverized coal circulating fluidized bed combustion system - Google Patents
Extremely narrow screening particle diameter pulverized coal circulating fluidized bed combustion system Download PDFInfo
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- CN114353059B CN114353059B CN202210074427.0A CN202210074427A CN114353059B CN 114353059 B CN114353059 B CN 114353059B CN 202210074427 A CN202210074427 A CN 202210074427A CN 114353059 B CN114353059 B CN 114353059B
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- 239000003245 coal Substances 0.000 title claims abstract description 278
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 38
- 239000002245 particle Substances 0.000 title claims abstract description 27
- 238000012216 screening Methods 0.000 title claims abstract description 14
- 239000000446 fuel Substances 0.000 claims abstract description 42
- 238000002360 preparation method Methods 0.000 claims abstract description 11
- 238000000926 separation method Methods 0.000 claims description 19
- 238000000227 grinding Methods 0.000 claims description 14
- 230000001276 controlling effect Effects 0.000 claims description 9
- 238000004891 communication Methods 0.000 claims description 6
- 230000005484 gravity Effects 0.000 claims description 6
- 238000009423 ventilation Methods 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 239000003344 environmental pollutant Substances 0.000 abstract description 3
- 231100000719 pollutant Toxicity 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 10
- 235000019738 Limestone Nutrition 0.000 description 7
- 230000033228 biological regulation Effects 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000006028 limestone Substances 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- 239000010881 fly ash Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 239000002956 ash Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 235000002918 Fraxinus excelsior Nutrition 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 239000002802 bituminous coal Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003203 everyday effect Effects 0.000 description 1
- 238000005243 fluidization Methods 0.000 description 1
- 239000003077 lignite Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- 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
Landscapes
- Fluidized-Bed Combustion And Resonant Combustion (AREA)
Abstract
The invention provides a pulverized coal circulating fluidized bed combustion system with extremely narrow screening particle size, which comprises a circulating fluidized bed boiler subsystem and a fuel preparation subsystem; the circulating fluidized bed boiler subsystem comprises a hearth, wherein a primary air inlet, a secondary air inlet and a tertiary air inlet are respectively arranged on the wall of the hearth; the fuel preparation subsystem comprises a raw coal bin, a coal mill, a pulverized coal separator and a coal feeder; the raw coal inlet of the coal mill is communicated with the raw coal bin, and the pulverized coal outlet of the coal mill is communicated with the inlet of the pulverized coal separator; the concentrated pulverized coal outlet of the pulverized coal separator is communicated with the first inlet of the coal feeder, and the conveying airflow outlet of the pulverized coal separator is communicated with the tertiary air inlet of the hearth; and the outlet of the coal feeder is communicated with the fuel inlet of the hearth. The technical scheme of the invention can effectively solve the reliability problem, the pollutant control problem and the overall economy problem of the circulating fluidized bed boiler.
Description
Technical Field
The invention relates to a circulating fluidized bed combustion system, in particular to a fuel preparation subsystem and a circulating fluidized bed boiler subsystem which can prepare and burn pulverized coal with extremely narrow screening particle size.
Background
Under the guidance of carbon peaks and carbon neutralization targets, china is actively transforming into energy production and consumption structures mainly comprising renewable energy sources. The intermittent and unpredictable nature of renewable energy sources makes the output fluctuation big, which presents a great challenge for the power grid regulation capability, and the traditional coal-fired power generator set is required to be converted to a basic guarantee and system regulation power supply. The circulating fluidized bed boiler has the excellent characteristics of low cost desulfurization, low emission of nitrogen oxides, large-scale load regulation, stable low-load operation and the like, and is the main force of participating in deep peak regulation of a power grid in the future. However, the design and the operation mode of the traditional circulating fluidized bed boiler restrict the exertion of the characteristics of the traditional circulating fluidized bed boiler, so that a large number of circulating fluidized bed boilers have low load adjustment rate, high fan power consumption and high plant power consumption. Therefore, the existing circulating fluidized bed boiler design and operation control mode are necessarily improved, the problems existing in the prior art are solved, the support energy is clean, low-carbon and green, and a novel power system is constructed.
Disclosure of Invention
The invention provides an extremely narrow screening particle size pulverized coal circulating fluidized bed combustion system, which aims to solve the problems of low load regulation rate, high fan power consumption and high station service power consumption of the existing circulating fluidized bed boiler.
The technical scheme of the invention is as follows:
a combustion system of a circulating fluidized bed of pulverized coal with extremely narrow screening particle size comprises a circulating fluidized bed boiler subsystem and a fuel preparation subsystem; the circulating fluidized bed boiler subsystem comprises a hearth, wherein a primary air inlet, a secondary air inlet and a tertiary air inlet are respectively arranged on the wall of the hearth;
the fuel preparation subsystem comprises a raw coal bin, a coal mill, a pulverized coal separator and a coal feeder; the raw coal inlet of the coal mill is communicated with the raw coal bin, and the pulverized coal outlet of the coal mill is communicated with the inlet of the pulverized coal separator; the concentrated pulverized coal outlet of the pulverized coal separator is communicated with the first inlet of the coal feeder, and the conveying airflow outlet of the pulverized coal separator is communicated with the tertiary air inlet of the hearth; and the outlet of the coal feeder is communicated with the fuel inlet of the hearth.
Optionally, the pulverized coal separator comprises a cyclone gas-solid distributor.
Optionally, the combustion system of the pulverized coal circulating fluidized bed with the ultra-narrow screening particle size comprises a preheater and a blower; the air feeder is respectively communicated with the preheating air channel and the cold air channel; the preheating air channel is communicated with the inlet of the preheater, and the outlet of the preheater is respectively communicated with the primary air channel, the secondary air channel and the coal grinding air channel; the primary air channel is communicated with the primary air inlet of the hearth; the secondary air channel is communicated with the secondary air inlet of the hearth; the coal grinding air channel is communicated with a conveying air inlet of the coal mill; the cold air channel is communicated with the coal grinding air channel.
Optionally, a cold air control valve is arranged on the cold air channel.
Optionally, the separation efficiency of the pulverized coal separator is controlled by controlling the opening degree of the cold air control valve.
Optionally, the ventilation volume passing through the tertiary air inlet accounts for 5% -10% of the air supply volume of the blower.
Optionally, the ventilation quantity of the primary air inlet accounts for 30% -40% of the air quantity of the blower; the ventilation quantity of the secondary air inlet accounts for 50% -65% of the air quantity of the air feeder.
Optionally, the tertiary air inlet is at a greater height on the wall of the furnace than the secondary air inlet; the height of the secondary air inlet on the wall of the hearth is larger than that of the primary air inlet on the wall of the hearth.
Optionally, the number of fuel inlets is greater than 1.
Optionally, at least part of the fuel inlets are arranged at different heights on the wall of the furnace.
Optionally, at least some of the fuel inlets are at different distances from a centerline of a front wall of the furnace; the center line of the front wall is parallel to a gravity direction line.
Optionally, a pulverized coal channel valve is arranged on a communication channel between the outlet of the coal feeder and the fuel inlet.
Optionally, a raw coal flow regulating device is arranged on a channel of the raw coal inlet communicated with the raw coal bin; and controlling the separation efficiency of the pulverized coal separator by controlling the raw coal flow regulating equipment.
Optionally, the coal feeder further comprises a coal feeder second inlet; the second inlet of the coal feeder is communicated with the raw coal bin; and a second inlet valve is arranged on a channel for communicating the second inlet of the coal feeder with the raw coal bin.
Optionally, the pulverized coal discharged from the pulverized coal outlet of the coal pulverizer has a particle size ranging from 0 mm to 1mm.
Optionally, the pressure drop of the bed is 2-5kPa when the combustion system of the pulverized coal circulating fluidized bed with the ultra-narrow screening particle size operates, and the differential pressure of a hearth is maintained at 2-8kPa.
The invention has the following technical effects:
the circulating fluidized bed combustion system adopts the novel fuel preparation subsystem, and the pulverized coal with extremely narrow screening particle size is prepared by the fuel preparation subsystem for combustion by the circulating fluidized bed boiler subsystem. The technical scheme of the invention utilizes the existing characteristics of the circulating fluidized bed boiler, combines the advantages of large specific surface area, strong reaction capability and high combustion efficiency of pulverized coal, can realize sufficiently high circulating flow rate and load fluctuation rate under the condition of lower bed pressure drop, not only greatly reduces the carbon content of fly ash, but also can reduce the power consumption of a fan and the power consumption of plants, and ensures that the circulating fluidized bed boiler has the capability of fast load lifting while realizing energy-saving and consumption-reducing operation. Meanwhile, the invention can effectively reduce NO by controlling the combustion temperature X The abrasion of the heating surface in the hearth of the circulating fluidized bed boiler can be reduced after the granularity of the fuel is reduced, so that the reliability problem, the pollutant control problem and the overall economy problem of the circulating fluidized bed boiler are solved.
Further effects of the above alternatives will be described below in connection with the embodiments.
Drawings
FIG. 1 is a schematic diagram of an embodiment of a combustion system for a circulating fluidized bed of pulverized coal with very narrow sieving characteristics according to the present invention.
Fig. 2 is a schematic view of the coal pulverizer in the embodiment of fig. 1.
The identification in the figures is as follows:
101. a furnace; 102. a circulating fluidized bed separator; 103. a tail flue; 104. a preheater; 105. a blower; 106. a cold air channel; 107. a cold air control valve; 108. a primary air inlet; 109. a secondary air inlet; 110. a coal grinding air channel; 111. a coal mill; 112. a coal feeder; 113. raw coal bin; 114. a pulverized coal separator; 115. a limestone powder bin; 116. a tertiary air inlet; 117. feeding into a coal grinding feeder;
201. a coal dropping pipe; 202. a pulverized coal outlet; 203. grinding roller; 204. a turntable; 205. a transmission mechanism; 206. a motor; 207. a delivery wind inlet; 208. and (5) pressing the frame.
Detailed Description
The technical scheme of the present invention will be described in detail with reference to the embodiments shown in the drawings.
FIG. 1 shows an example of the very narrow screened particle size pulverized coal circulating fluidized bed combustion system of the present invention. The circulating fluidized bed combustion system comprises a circulating fluidized bed boiler subsystem and a fuel preparation subsystem.
The circulating fluidized bed boiler subsystem comprises a furnace 101, a circulating fluidized bed separator 102 and a tail flue 103. The hearth 101 and the circulating fluidized bed separator 102 communicated with the hearth form a material circulating system, and the tail flue 103 is used for treating waste gas separated by the circulating fluidized bed separator 102, so that the purposes of energy and material recovery and smoke purification are achieved. The walls of the furnace 101 are provided with a primary air inlet 108, a secondary air inlet 109 and a tertiary air inlet 116, respectively.
The fuel preparation subsystem includes raw coal bunker 113, coal pulverizer 111, pulverized coal separator 114, and coal feeder 112. The raw coal inlet of the coal mill 111 communicates with the raw coal bin 113. The raw coal bunker 113 is used for storing raw coal. Examples of raw coal are raw coal such as bituminous coal, anthracite coal, lean coal, lignite coal or a mixture of several of them. Raw coal in raw coal silo 113 enters coal mill 111 through raw coal inlets (coal drop tubes 201 in fig. 2) of coal inlet mill 117 and coal mill 111. The raw coal bin 113 is also in communication with one inlet (second inlet) of the coal feeder 112. A second inlet valve (not shown) is provided in the passageway of the raw coal silo 113 communicating with the coal feeder 112. The pulverized coal ground by the coal mill 111 enters the pulverized coal separator 114 through a communication path between a pulverized coal outlet of the coal mill 111 and an inlet of the pulverized coal separator 114. The concentrated pulverized coal outlet of the pulverized coal separator 114 communicates with a first inlet of the coal feeder 112, and the conveying air outlet of the pulverized coal separator 114 communicates with a tertiary air inlet 116 on the furnace 101. The coal feeder 112 is a screw feeder that can adjust the coal feeding speed. The outlet of the coal feeder 112 communicates with the fuel inlet of the furnace 101. In the present embodiment, the pulverized coal separator 114 is a cyclone type gas-solid distributor (also referred to as a cyclone separator), that is, a cyclone separation principle is used to split the gas-solid of the pulverized coal and distribute the concentrated pulverized coal and the conveying gas flow.
A preheater 104 is provided in the tail flue 103, and the preheater 104 is a heat exchanger, and is capable of transferring heat between at least two different substances without mixing, in this embodiment, heat exchange is performed between the tail flue gas and the wind input from the blower 105. The blower 105 is, for example, a device that generates wind having a certain flow direction and a certain flow rate by a blower. The air outlets of the blower 105 are respectively communicated with the preheating air passage and the cold air passage 106. The preheat wind passage communicates with an inlet of the preheater 104. The outlets of the preheaters 104 are respectively communicated with a primary air inlet 108 through a primary air passage, a secondary air inlet 109 through a secondary air passage, and a conveying air inlet 207 (see fig. 2) of a coal mill 111 through a coal grinding air passage 110. The blower 105 communicates with the ground coal air passage 110 through the cool air passage 106. A cool air control valve 107 is provided in the cool air passage 106.
With the bottom of the furnace 101 shown in fig. 1 as a reference, the distance above the reference is the height on the wall of the furnace 101, and then the height of the tertiary air inlet 116 on the wall of the furnace 101 is greater than the height of the secondary air inlet 109 on the wall of the furnace 101, and the height of the secondary air inlet 109 on the wall of the furnace 101 is greater than the height of the primary air inlet 108 on the wall of the furnace 101. The coal feeder 112 is connected to the fuel inlets of the furnace 101, three of which are each different in height on the wall of the furnace 101. Pulverized coal channel valves (not shown) are respectively arranged on three channels of the outlet of the coal feeder 112 communicated with the fuel inlet.
The limestone powder bin 115 communicates with the feeder and delivers limestone powder to the firebox 101 through the feeder. The powder outlet of the powder feeder is connected to the secondary air inlet 109.
The working process of the embodiment shown in fig. 1 is described below to further clarify the technical scheme of the present invention.
The working process of the pulverized coal circulating fluidized bed combustion system with the extremely-narrow screening particle size is as follows.
Referring to fig. 2, raw coal in raw coal silo 113 enters through raw coal inlet (coal drop tube 201) of coal feed 117 and coal pulverizer 111 onto turntable 204 in coal pulverizer 111. Turntable 204 is driven to rotate by motor 206 through transmission 205. The grinding roller 203 can roll. Under the pressure applied to the turntable 204 by the hydraulic equipment through the press frame 208 and the gravity of the grinding roll 203, the raw coal is crushed and ground with the rotation of the turntable 204, and finally ground into pulverized coal. The pulverized coal moves toward the edge of the disk of the turntable 204 under the pushing action of centrifugal force and the input raw coal, and is finally thrown out in the tangential direction of the turntable 204. After being mixed with the pulverized coal, the conveying air entering through the conveying air inlet 207 conveys the pulverized coal to an upper area inside the coal mill 111, and the pulverized coal particles with larger particle sizes fall down to the rotary disc 204 due to gravity and continue to be re-ground; the smaller size pulverized coal particles are carried by the conveying wind through the pulverized coal outlet 202 out of the coal pulverizer 111. In this embodiment, the size of the pulverized coal discharged from the coal pulverizer 111 through the pulverized coal outlet 202 is in the range of 0 to 1mm.
The wind carrying the pulverized coal exits the coal pulverizer 111 and enters the pulverized coal separator 114 through a tangential inlet of the pulverized coal separator 114. In the pulverized coal separator 114, the wind of the mixed pulverized coal is separated by the combined action of gravity and centrifugal force, and the separated pulverized coal enters the first inlet of the coal feeder 112 through the concentrated pulverized coal outlet, and is further fed into the furnace 101 by the coal feeder 112. The separated gas enters the furnace 101 through the tertiary air inlet 116 of the furnace 101 through the conveying air outlet of the pulverized coal separator 114. By arranging the tertiary air inlet 116, the air transmitted by the coal mill 111 can be used as the ashes of the hearth 101, the combustion efficiency of the pulverized coal in the hearth 101 is improved, the carbon content of fly ash and the carbon content of bottom slag are reduced, the lifting load can be supplemented to the coal feeding port during peak regulation operation of the circulating fluidized bed system, and the lifting load can be rapidly realized by adjusting the mass flow rate of the pulverized coal fed in the position.
The preheated air preheated by the blower 105 through the preheater 104 is injected into the furnace 101 and the coal mill 111, respectively. Wherein, the preheated air injected into the hearth 101 is respectively used as primary air and secondary air to enter the hearth 101; part of the preheated air also enters the coal mill 111 as an integral part of the conveying air injected into the coal mill 111. Specifically, the primary air entering through the primary air inlet 108 is injected through an air distribution device (not shown in the figure) at the bottom of the furnace 101, the secondary air entering through the secondary air inlet 109 is injected from the middle of the furnace 101, and enters into the coal mill 111 through the coal grinding air channel 110 (entering through the conveying air inlet 207 of the coal mill 111). The blower 105 also has a part of the air that enters the mill air duct 110 through the cool air duct 106, mixes with the preheated air therein, and enters the coal mill 111 as the air-feeding air. The air quantity entering the hearth 101 through the primary air inlet 108 accounts for 30% -40% of the air quantity of the blower 105; the air quantity entering the hearth 101 through the secondary air inlet 109 accounts for 50% -65% of the air quantity of the blower 105; the volume of air entering the furnace 101 through the tertiary air inlet 116 is 5% -10% of the volume of air supplied by the blower 105.
Limestone is fed from limestone powder bin 115 through a feeder into furnace 101 and mixed with fuel to effect in-furnace desulfurization.
The cyclic combustion process inside the furnace 101 is as follows: the pulverized coal particles with the granularity of 0-1mm enter a dense-phase region at the bottom of the hearth 101 through a fuel inlet of the hearth 101 to be heated, and are mixed with circulating ash entering the bottom of the hearth 101 through a return pipe to form a material, and the material is conveyed to a transition section region in the hearth 101 under the action of the fluidization wind of the wind distribution device. The material continues to be fed to the upper dilute phase zone of the furnace 101 as a result of the primary and secondary air. Subsequently, particles with a particle size of more than 300 μm are reflowed to the inner wall of the hearth 101 to form an internal circulation material, after fine materials with a particle size of less than 300 μm enter the circulating fluidized bed separator 102, 99.9% of the materials are captured to form an external circulation material, and the rest of the superfine materials are carried into the tail flue 103 in the form of fly ash by flue gas. A superheater (reheater), an economizer and a preheater 104 are arranged in sequence in the tail flue 103. And finally, the tail flue gas is treated by a flue gas treatment device until reaching the emission standard and is then emitted.
The combustion system of the pulverized coal circulating fluidized bed with the extremely-narrow screening particle size has the characteristics of high reliability and flexible adjustment load. Embodied in the following aspects.
Since the raw coal bin 113 is also in communication with the second inlet of the coal feeder 112, a second inlet valve is provided on the passageway of the raw coal bin 113 in communication with the coal feeder 112. The second inlet valve is in a closed state every day, and raw coal in the raw coal bin 113 is conveyed to the coal mill 111 for grinding and then is injected into the hearth 101. When the coal mill 111 or a path communicated with the coal mill and leading to the coal feeder 112 fails and coal cannot be supplied to the hearth 101, the second inlet valve can be opened, so that raw coal in the raw coal bin 113 can directly enter the coal feeder 112 and then be injected into the hearth 101, the operation of the circulating fluidized bed system is maintained, and large loss is avoided.
The separation efficiency of the pulverized coal separator 114 can be adjusted according to the operating load of the extremely narrow screened particle size pulverized coal circulating fluidized bed combustion system. When the circulating fluidized bed combustion system needs to lift load, the separation efficiency of the pulverized coal separator 114 is reduced, so that more pulverized coal enters a dilute phase zone with good combustion conditions through a tertiary air inlet 116 of the boiler, combustion is realized rapidly, and heat is released; when the circulating fluidized bed combustion system needs load reduction, the separation efficiency of the pulverized coal separator 114 is improved, and the pulverized coal mainly enters a dense phase zone at the bottom of the hearth 101 through a fuel inlet. The separation efficiency of the pulverized coal separator referred to in the present invention means a ratio of the mass of pulverized coal discharged from the concentrated pulverized coal outlet of the pulverized coal separator 114 to the mass of pulverized coal entered from the inlet of the pulverized coal separator 114. The pressure drop of the bed is 2-5kPa when the combustion system of the pulverized coal circulating fluidized bed with the extremely-narrow sieving particle size operates, and the differential pressure of a hearth is maintained at 2-8kPa. Bed pressure drop refers to the pressure drop across the furnace, i.e., the pressure differential from the bottom of the furnace to the top of the furnace; the furnace differential pressure refers to the pressure drop in the upper dilute phase zone of the furnace.
The above-described adjustment of the separation efficiency of the pulverized coal separator 114 may be achieved by:
(1) The number of fuel inlets to the furnace 101 to which the coal feeder 112 is connected is plural, and the height of each of the fuel inlets is different, which means that the back pressure at the different fuel inlets (i.e. the pressure in the furnace 101 reacting against the pressure at the fuel inlets) is different, and the higher the height, the smaller the back pressure. If the back pressure at the outlet increases, which corresponds to an increase in the pressure in the concentrated coal outlet of the pulverized coal separator 114, the separation efficiency of the pulverized coal separator 114 may decrease; if the back pressure at the outlet is reduced, the separation efficiency of the pulverized coal separator 114 may be increased. Thus, the above-described adjustment of the separation efficiency of the pulverized coal separator 114 can be achieved by opening or closing pulverized coal channel valves on different channels in which the outlet of the coal feeder 112 communicates with the fuel inlet.
In addition, the fuel inlets are provided on the front wall of the furnace 101, and the back pressure at the fuel inlets is different if the fuel inlets are located at different distances from the center line of the front wall of the furnace 101. The center line of the front wall is parallel to the gravity direction line, i.e. the center line of the front wall is perpendicular to the horizontal plane. The law of the back pressure distribution is: the closer the distance from the center line of the front wall of the furnace 101, the smaller the back pressure. Thus, in other embodiments, different back pressures at different fuel inlets can be provided by providing different distances of the different fuel inlets from the centerline of the front wall of the furnace 101. The separation efficiency of the pulverized coal separator 114 may be further adjusted by opening or closing pulverized coal channel valves on different channels through which the outlet of the coal feeder 112 communicates with the fuel inlet.
(2) The wind speed at the inlet of the pulverized coal separator 114 increases, and the separation efficiency of the pulverized coal separator 114 increases; the wind speed at the inlet of the pulverized coal separator 114 decreases, and the separation efficiency of the pulverized coal separator 114 decreases. The source of wind at the inlet of pulverized coal separator 114 is the feed wind of coal pulverizer 111, and the feed wind constitutes the wind from the preheating wind and the cooling wind tunnel 106. The preheated air, which constitutes the supply air, is associated with primary and secondary air, and the total amount of primary and secondary air is generally stable with little variation, so that the wind speed at the inlet of the separator 114 can be controlled by adjusting the amount of air in the cold air duct 106. I.e. the regulation of the wind speed at the inlet of the separator 114 is achieved by means of a cold air control valve 107.
(3) The coal inlet mill 117 that conveys raw coal to the coal mill 111 may also be used as a raw coal flow rate adjustment device, i.e., by adjusting the amount of raw coal that is input to the coal mill 111 by the coal inlet mill 117. The separation efficiency of the pulverized coal separator 114 can be improved when the amount of raw coal input to the coal pulverizer 111 is reduced; the separation efficiency of the pulverized coal separator 114 may be reduced when the amount of raw coal input to the coal pulverizer 111 is increased. Of course, the premise of adjusting the amount of raw coal input to the coal pulverizer 111 is that the requirements of the circulating fluidized bed boiler subsystem should be satisfied.
According to the combustion system of the pulverized coal circulating fluidized bed with the extremely-narrow screening particle size, as the pulverized coal particle size is low, the contact area of limestone and pulverized coal particles is increased, the mixing is more sufficient, the desulfurization efficiency is improved, the using amount of the limestone is reduced, and the cost is saved. In addition, the technical scheme of the invention utilizes the existing characteristics of the circulating fluidized bed boiler, combines the advantages of large specific surface area, strong reaction capability and high combustion efficiency of pulverized coal, can realize sufficiently high circulating flow rate and load fluctuation rate under the condition of lower bed pressure drop, not only greatly reduces the carbon content of fly ash, but also reduces the power consumption and station service power consumption of a fan, and ensures that the circulating fluidized bed boiler has the capability of fast load lifting while realizing energy-saving and consumption-reducing operation. Meanwhile, the invention can effectively reduce NO by controlling the combustion temperature X The abrasion of the heating surface in the hearth of the circulating fluidized bed boiler can be reduced after the granularity of the fuel is reduced, so that the reliability problem, the pollutant control problem and the overall economy problem of the circulating fluidized bed boiler are solved.
It should be noted that the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the invention, and the present invention can be replaced by equivalent technology. It is intended that all equivalent variations in the description and illustrations of the invention, or the direct or indirect application to other relevant art, be included within the scope of the invention.
Claims (9)
1. An extremely narrow screening particle diameter fine coal circulating fluidized bed combustion system which is characterized in that: comprises a circulating fluidized bed boiler subsystem and a fuel preparation subsystem; the circulating fluidized bed boiler subsystem comprises a hearth, wherein a primary air inlet, a secondary air inlet and a tertiary air inlet are respectively arranged on the wall of the hearth;
the fuel preparation subsystem comprises a raw coal bin, a coal mill, a pulverized coal separator and a coal feeder; the raw coal inlet of the coal mill is communicated with the raw coal bin, and the pulverized coal outlet of the coal mill is communicated with the inlet of the pulverized coal separator; the concentrated pulverized coal outlet of the pulverized coal separator is communicated with the first inlet of the coal feeder, and the conveying airflow outlet of the pulverized coal separator is communicated with the tertiary air inlet of the hearth; the outlet of the coal feeder is communicated with the fuel inlet of the hearth;
the pulverized coal separator comprises a cyclone type gas-solid distributor;
comprises a preheater and a blower; the air feeder is respectively communicated with the preheating air channel and the cold air channel; the preheating air channel is communicated with the inlet of the preheater, and the outlet of the preheater is respectively communicated with the primary air channel, the secondary air channel and the coal grinding air channel; the primary air channel is communicated with the primary air inlet of the hearth; the secondary air channel is communicated with the secondary air inlet of the hearth; the coal grinding air channel is communicated with a conveying air inlet of the coal mill; the cold air channel is communicated with the coal grinding air channel;
a cold air control valve is arranged on the cold air channel;
controlling the separation efficiency of the pulverized coal separator by controlling the opening degree of the cold air control valve;
the number of fuel inlets is greater than 1;
at least part of the fuel inlets are arranged at different heights on the wall of the furnace chamber;
at least some of the fuel inlets are at different distances from a centerline of a front wall of the furnace; the center line of the front wall is parallel to the gravity direction line;
the separation efficiency of the pulverized coal separator is adjusted by opening or closing different fuel inlets.
2. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: the ventilation quantity of the tertiary air inlet accounts for 5% -10% of the air quantity of the blower.
3. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 2, wherein: the ventilation quantity of the primary air inlet accounts for 30% -40% of the air quantity of the air feeder; the ventilation quantity of the secondary air inlet accounts for 50% -65% of the air quantity of the air feeder.
4. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: the height of the tertiary air inlet on the wall of the hearth is larger than that of the secondary air inlet on the wall of the hearth; the height of the secondary air inlet on the wall of the hearth is larger than that of the primary air inlet on the wall of the hearth.
5. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: and a pulverized coal channel valve is arranged on a communication channel between the outlet of the coal feeder and the fuel inlet.
6. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: a raw coal flow regulating device is arranged on a channel of the raw coal inlet communicated with the raw coal bin; and controlling the separation efficiency of the pulverized coal separator by controlling the raw coal flow regulating equipment.
7. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: the coal feeder further comprises a coal feeder second inlet; the second inlet of the coal feeder is communicated with the raw coal bin; and a second inlet valve is arranged on a channel for communicating the second inlet of the coal feeder with the raw coal bin.
8. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: the granularity range of the pulverized coal discharged from the pulverized coal outlet of the coal mill is 0-1mm.
9. The ultra-narrow screen size pulverized coal circulating fluidized bed combustion system as set forth in claim 1, wherein: when the combustion system of the circulating fluidized bed with the pulverized coal with extremely-narrow screening particle size operates, the pressure drop of the bed is 2-5kPa, and the differential pressure of a hearth is maintained at 2-8kPa.
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