CN114558685A - Method for determining maximum allowable temperature of outlet of coal mill - Google Patents
Method for determining maximum allowable temperature of outlet of coal mill Download PDFInfo
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- CN114558685A CN114558685A CN202210193009.3A CN202210193009A CN114558685A CN 114558685 A CN114558685 A CN 114558685A CN 202210193009 A CN202210193009 A CN 202210193009A CN 114558685 A CN114558685 A CN 114558685A
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- coal
- maximum allowable
- coal mill
- outlet
- temperature
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
- B02C23/04—Safety devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C25/00—Control arrangements specially adapted for crushing or disintegrating
-
- 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
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
Abstract
The invention discloses a method for determining the maximum allowable temperature of an outlet of a coal mill, which comprises the following steps: 1) obtaining the total moisture, the received basic ash content, the dried ash-free basic volatile matter and the received basic volatile matter of the coal sample; 2) calculating the theoretical maximum allowable temperature of the coal mill outlet of the coal type through the coal quality parameters; 3) and obtaining the final recommended maximum allowable temperature of the outlet of the coal mill according to the calculation result and the relevant conditions. The influence of key coal quality indexes such as coal types, coal moisture, ash content, volatile matters and the like on the explosion performance of the pulverized coal is comprehensively considered, and the determination of the maximum allowable temperature of the outlet of the coal mill from the explosion characteristic of the coal is more scientific and reasonable. The invention can improve the operation safety of the pulverizing system, reduce the power consumption of the pulverizing system and improve the combustion economy of the boiler. The invention can be realized by adjusting the system operation mode, and has the advantages of small investment and high profit.
Description
Technical Field
The invention relates to the technical field of boiler operation optimization, in particular to a method for determining the highest allowable temperature of an outlet of a coal mill, which is suitable for a direct-blowing medium-speed grinding system and does not contain the start-stop working condition of the coal mill under the normal operation working condition of the grinding system.
Background
The coal pulverizing system is one of main auxiliary machines of a coal-fired power plant, the operation stability of the coal pulverizing system directly influences the combustion working condition of a boiler, wherein the explosion of the direct-blowing coal pulverizing system can not only cause the damage of a coal mill and accessories thereof, but also threaten the safety of the boiler, so that the explosion prevention of the coal pulverizing system is one of main prevention and control targets of the operation of the coal mill. Explosion protection of the coal pulverizing system is mainly used for reducing the outlet temperature of a coal mill. The maximum allowable temperature T of the coal mill outlet of different coal pulverizing systems is definitely specified in the standard DL/T466-2004 power station coal mill and coal pulverizing system model selection guide ruleM2(DEG C) selection principle, wherein t of medium-speed mill direct-blowing pulverizing systemM2The selection principle of the (DEG C) is as follows:
when V isdafWhen the content is less than 40 percent,
when V isdafWhen t is more than or equal to 40 percentM2＜70
Meanwhile, the requirement that the highest temperature of an outlet of the coal mill is 2 ℃ higher than the dew point temperature is met. As can be seen from the guideline, the method primarily takes into account VdafThe influence on the safe operation of the coal pulverizing system does not consider the factors of increasing the coal powder porosity due to water analysis, reducing the coal powder explosion tendency due to increasing ash content and the likeThe impact, especially on high ash bituminous coals with low propensity to explode, can result in low control of the mill exit temperature and even impact combustion stability and safety. In addition, the selection method can also cause that the outlet temperature of the coal mill of part of coal types is selected too low, so that the overall operation economy of the boiler is reduced.
The outlet temperature of the coal mill is increased, so that considerable economic benefits can be brought, but the danger of explosion can be brought to a coal pulverizing system, and a clear principle for determining the index is not provided at present.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a method for determining the maximum allowable temperature of an outlet of a coal mill, which is suitable for a direct-fired medium-speed coal pulverizing system.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method of determining a maximum allowable coal mill outlet temperature, comprising the steps of:
1) obtaining the total moisture, the received basic ash content, the dried ash-free basic volatile matter and the received basic volatile matter of the coal sample;
2) calculating the theoretical maximum allowable temperature of the coal mill outlet of the coal type through the coal quality parameters;
3) and obtaining the final recommended maximum allowable temperature of the outlet of the coal mill according to the calculation result and the relevant conditions.
In a further development of the invention, in step 1), the coal sample has a total moisture content, an as-received ash content, a dry ashless-based volatile matter content and an as-received volatile matter content each expressed as Mt、Aar、VdafAnd VarThe units are%.
The invention further improves that in the step 2), the theoretical maximum allowable temperature of the coal mill outlet of the coal type is expressed as ttM2jIn units of ℃.
A further development of the invention is that, in step 2), if VarLess than or equal to 18, then
ttM2j＝-0.5856Mt+0.6971Aar-0.9151Vdaf+137.72 (formula 1).
A further development of the invention is that, in step 2), if VarGreater than 18, then
ttM2j＝-0.4505Mt+0.5362Aar-0.7039Vdaf+105.84 (formula 2).
A further development of the invention is that in step 3), if ttM2j>55, obtaining the coal pulverizing system in tt according to DL/T5145 and 2012 Standard of design and calculation technology of coal pulverizing System of thermal power plantM2jOutlet dew point temperature t of lower coal milldpIn units of ℃.
A further development of the invention is that if ttM2j≥tdp+2, then ttM2＝ttM2jOtherwise ttM2j<tdp+2, then ttM2＝tdp+2。
A further development of the invention is that in step 3), if ttM2jLess than or equal to 55, and obtaining the dew point temperature T of the outlet temperature of the coal mill at 55 ℃ according to design calculation technical regulation of powder making system of DL/T5145 and 2012 thermal power plantdp55In units of ℃.
A further development of the invention is that if t isdp55Tt is determined when the ratio is less than or equal to 53M2If t is 55, if tdp55>53, then ttM2＝tdp55+2。
Compared with the prior art, the invention has at least the following beneficial technical effects:
1) the influence of key coal quality indexes such as coal types, moisture, ash content and volatile matters of the coal and the like on the explosion performance of the pulverized coal is comprehensively considered, and then the maximum allowable temperature t of the outlet of the coal mill is determined according to the explosion characteristic of the coalM2More scientific and reasonable.
2) According to the invention, on the basis of ensuring the safe operation of the coal pulverizing system, the outlet temperature of the coal pulverizer can be properly increased when the coal pulverizer normally operates, so that the power consumption of the coal pulverizing system can be reduced, the smoke exhaust temperature of a boiler can be reduced, and the combustion economy of the boiler can be improved.
3) For the lignite unit, the primary air rate can be reduced, the generation concentration of NOx is reduced, and the combustion economy is improved.
4) The invention can be realized by adjusting the system operation mode, and has the advantages of low investment and high yield.
Detailed Description
Exemplary embodiments of the present disclosure are described in more detail below. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
Case 1 is a maximum allowable coal mill outlet temperature tt of ligniteM2Is determined
The first step is as follows: obtaining the total moisture M of the coal sample according to the related datat(%), received basal Ash Aar(%), dry ashless base volatile Vdaf(%), volatile component V of the resulting residuear(％)。
M of this brown coalt34.8% of basic ash Aar3.14% dry ash-free base volatile component Vdaf51.74% of the volatile matter Var＝32.11％。
The second step is that: calculating theoretical maximum allowable temperature tt of coal mill outlet of coal typeM2j(. degree. C.), in particular, see formula (1) or (2)
If VarLess than or equal to 18, then
ttM2j＝-0.5856Mt+0.6971Aar-0.9151Vdaf+137.72 (formula 1)
Otherwise
ttM2j＝-0.4505Mt+0.5362Aar-0.7039Vdaf+105.84 (type 2)
This time of the volatile component V of the receiving group of the lignitear＝32.11>18, then ttM2jThe calculation adopts formula (2), specifically as follows:
ttM2j＝-0.4505×34.8+0.5362×3.14-0.7039×51.74+105.94＝55.53
the third step: determining the maximum allowable temperature tt of the coal mill outletM2The specific principle is as follows:
(1) if ttM2j>55, obtaining the powder manufacturing system design and calculation technical specification of the coal-fired power plant at tt according to DL/T5145 and 2012M2jOutlet dew point temperature t of lower coal milldp(℃)
(if tt)M2j≥tdp+2, then ttM2＝ttM2j
② otherwise ttM2j<tdp+2, then ttM2＝tdp+2
(2) If ttM2jLess than or equal to 55, and obtaining the dew point temperature T of the outlet temperature of the coal mill at 55 ℃ according to design calculation technical regulation of powder making system of DL/T5145 and 2012 thermal power plantdp55(℃)。
①tdp55Tt is determined when the ratio is less than or equal to 53M2＝55
②tdp55>53, then ttM2＝tdp55+2
This time ttM2j＝55.53>55, obtaining the powder manufacturing system design and calculation technical specification of the coal-fired power plant at tt according to DL/T5145 and 2012M2jOutlet dew point temperature t of lower coal milldp52, ttM2j＝55.53≥tdpThe + 2+ 54 is the first case of the (1) th case, therefore, the maximum allowable temperature tt of the coal mill outlet is obtainedM2＝ttM2j55.53 ℃. According to the regulations of DL/T466-2004 power station coal mill and pulverizing system model selection guide, the maximum allowable temperature of the coal mill outlet is 60-70 ℃, and the maximum allowable temperature of the coal mill outlet theory recommended in the current time is lower than the guide recommendation, mainly considering that the coal is extremely high in explosiveness, and in addition, the lower coal mill outlet temperature can reduce the primary air rate and effectively reduce the NOx generation concentration of the boiler.
Case 2 is the pulverizer outlet maximum allowable temperature tt for high ash bituminous coalsM2Is determined
The first step is as follows: obtaining the total moisture M of the coal sample according to the related datat(%), received basal Ash Aar(%), dry ashless base volatile Vdaf(%), volatile component V of the resulting residuear(％)。
M of this brown coalt14.7% of basic ash Aar45.61% dry ash-free base volatile component Vdaf51.05% by weight, the volatile fraction V was obtainedar＝20.26％
The second step is that: calculating theoretical maximum allowable temperature tt of coal mill outlet of coal typeM2j(. degree. C.), in particular, see formula (1) or (2)
If VarLess than or equal to 18, then
ttM2j＝-0.5856Mt+0.6971Aar-0.9151Vdaf+137.72 (formula 1)
Otherwise
ttM2j＝-0.4505Mt+0.5362Aar-0.7039Vdaf+105.84 (type 2)
This time, the volatile matter V of the receiving base of the high ash bituminous coalar＝20.26>18, then ttM2jThe calculation adopts formula (2), specifically as follows:
ttM2j＝-0.4505×14.7+0.5362×45.61-0.7039×51.05+105.94＝87.84
the third step: determining the maximum allowable coal mill outlet temperature ttM2The specific principle is as follows:
(1) if ttM2j>55, obtaining the powder manufacturing system design and calculation technical specification of the coal-fired power plant at tt according to DL/T5145 and 2012M2jOutlet dew point temperature t of lower coal milldp(℃)
(if tt)M2j≥tdp+2, then ttM2＝ttM2j
② otherwise ttM2j<tdp+2, then ttM2＝tdp+2
(2) If ttM2jLess than or equal to 55, and obtaining the dew point temperature T of the outlet temperature of the coal mill at 55 ℃ according to design calculation technical regulation of powder making system of DL/T5145 and 2012 thermal power plantdp55(℃)。
①tdp55Tt is determined when the number is less than or equal to 53M2＝55
②tdp55>53, then ttM2＝tdp55+2
This time ttM2j＝87.84>55, obtaining the powder manufacturing system design and calculation technical specification of the coal-fired power plant at tt according to DL/T5145 and 2012M2jOutlet dew point temperature t of lower coal milldpAt 48 deg.C, i.e. ttM2j＝87.84≥tdp+ 2-48 + 2-50, which is the case of the first case (1), and therefore the maximum allowable coal mill outlet temperature ttM2＝ttM2j87.84 ℃. According to the regulations of DL/T466-2004 power station coal mill and powder process system model selection guide, the maximum allowable temperature of the coal mill outlet is 60-70 ℃, the maximum allowable temperature of the coal mill outlet recommended in the present time is 18-28 ℃ higher than the recommended guide value, and the coal is mainly considered to have higher ash content and greatly reduced explosion tendency of coal powder although the volatile component of the coal is higher, so that the temperature of the coal mill outlet can be increased, the combustion stability can be enhanced, the cold air is reduced, and the boiler efficiency can be improved.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (9)
1. A method of determining a maximum allowable coal mill outlet temperature, comprising the steps of:
1) obtaining the total moisture, the received basic ash content, the dried ash-free basic volatile matter and the received basic volatile matter of the coal sample;
2) calculating the theoretical maximum allowable temperature of the coal mill outlet of the coal type through the coal quality parameters;
3) and obtaining the final recommended maximum allowable temperature of the outlet of the coal mill according to the calculation result and the relevant conditions.
2. The method for determining the maximum allowable coal mill outlet temperature of claim 1, wherein in step 1), the total moisture, the received base ash, the dried ash-free base volatiles and the received base volatiles of the coal sampleExpressed as M respectivelyt、Aar、VdafAnd VarThe units are%.
3. The method for determining the maximum allowable coal mill outlet temperature as claimed in claim 2, wherein in step 2), the theoretical maximum allowable coal mill outlet temperature for the coal type is represented by ttM2jIn units of ℃.
4. The method for determining the maximum allowable coal mill outlet temperature as claimed in claim 3, wherein in step 2), if V is greater than VarLess than or equal to 18, then
ttM2j＝-0.5856Mt+0.6971Aar-0.9151Vdaf+137.72 (formula 1).
5. The method for determining the maximum allowable coal mill outlet temperature as claimed in claim 4, wherein in step 2), if V is greater than VarGreater than 18, then
ttM2j＝-0.4505Mt+0.5362Aar-0.7039Vdaf+105.84 (formula 2).
6. The method for determining the maximum allowable coal mill outlet temperature as set forth in claim 5, wherein in step 3), if ttM2j>55, obtaining the powder manufacturing system design and calculation technical specification of the coal-fired power plant at tt according to DL/T5145 and 2012M2jOutlet dew point temperature t of lower coal milldpIn units of ℃.
7. The method of determining the maximum allowable coal pulverizer outlet temperature of claim 6, wherein tt isM2j≥tdp+2, then ttM2＝ttM2jOtherwise ttM2j<tdp+2, then ttM2＝tdp+2。
8. A determination according to claim 6Method for the maximum permissible temperature of the coal mill outlet, characterized in that in step 3), if ttM2jLess than or equal to 55, and obtaining the dew point temperature T of the outlet temperature of the coal mill at 55 ℃ according to design calculation technical regulation of powder making system of DL/T5145 and 2012 thermal power plantdp55In units of ℃.
9. The method of determining the maximum allowable coal mill outlet temperature of claim 8, wherein if t is greater than a predetermined thresholddp55Tt is determined when the ratio is less than or equal to 53M2If t is 55, if tdp55>53, then ttM2＝tdp55+2。
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Cited By (1)
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| CN116060200A (en) * | 2023-03-06 | 2023-05-05 | 北京博数智源人工智能科技有限公司 | Deflagration early warning method and system for coal mill of thermal power station |
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| CN116060200A (en) * | 2023-03-06 | 2023-05-05 | 北京博数智源人工智能科技有限公司 | Deflagration early warning method and system for coal mill of thermal power station |
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