CN114558685B - 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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- CN114558685B CN114558685B CN202210193009.3A CN202210193009A CN114558685B CN 114558685 B CN114558685 B CN 114558685B CN 202210193009 A CN202210193009 A CN 202210193009A CN 114558685 B CN114558685 B CN 114558685B
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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
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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
- 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-fired medium-speed coal milling system, and is suitable for the normal operation condition of the coal milling system and the start-stop condition of the coal mill.
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 coal mill outlets of different coal pulverizing systems is specified in the standard DL/T466-2004 power station coal mill and coal pulverizing system model selection guide rule in the power industry M2 (DEG C) selection principle, wherein t of medium-speed mill direct-blowing pulverizing system M2 The selection principle of the temperature is as follows:
when V is daf When the content is less than 40 percent,
when V is daf When t is more than or equal to 40 percent M2 ＜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 V daf The influence on the safe operation of a pulverizing system does not consider the influence of multiple factors such as increased explosion tendency caused by increased porosity of coal powder and reduced explosion tendency of ash content increased coal powder due to water analysis, and particularly the influence on combustion stability and safety caused by too low control of the outlet temperature of a coal mill can be caused for high-ash bituminous coal with lower explosion tendency. 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, and 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 of 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 base ash content, the dried ash-free base volatile matter and the received base 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.
A further improvement of the invention is that in step 1), the expressions total moisture, as-received ash, dry ashless based volatiles and as-received volatiles of the coal sample are respectively M t 、A ar 、V daf And V ar The 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 tt M2j In units of ℃.
A further development of the invention is that, in step 2), if V ar Less than or equal to 18, then
tt M2j ＝-0.5856M t +0.6971A ar -0.9151V daf +137.72 (formula 1).
A further development of the invention is that, in step 2), if V ar Greater than 18, then
tt M2j ＝-0.4505M t +0.5362A ar -0.7039V daf +105.84 (formula 2).
A further development of the invention is that in step 3), if tt M2j >55, obtaining the powder manufacturing system design and calculation technical specification of DL/T5145-2012 thermal power plant at tt M2j Ground coalMachine outlet dew point temperature t dp In units of ℃.
A further development of the invention is that if tt M2j ≥t dp +2, then tt M2 ＝tt M2j Otherwise tt M2j <t dp +2, then tt M2 ＝t dp +2。
A further development of the invention is that in step 3), if tt M2j Less than or equal to 55, and obtaining the dew point temperature T of 55 ℃ at the outlet temperature of the coal mill according to design calculation technical regulation of powder making system of DL/T5145-2012 thermal power plant dp55 In units of ℃.
A further development of the invention is that if t is dp55 Tt is determined when the ratio is less than or equal to 53 M2 =55, if t dp55 >53, then tt M2 ＝t dp55 +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 coal M2 More 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 mill can be properly increased when the coal mill normally operates, the power consumption of the coal pulverizing system can be reduced, the smoke exhaust temperature of the 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 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 lignite M2 Is determined
The first step is as follows: obtaining the total moisture M of the coal sample according to the related data t (%), and the base ash A ar (%), dry ashless based volatile V daf (%), recovery of the base volatile V ar (％)。
M of this brown coal t =34.8%, basic ash content a was received ar =3.14%, dry ash-free base volatile component V daf =51.74% received radical volatiles V ar ＝32.11％。
The second step: calculating theoretical maximum allowable temperature tt of coal mill outlet of coal type M2j (. Degree. C.), in particular, see formula (1) or (2)
If V ar Less than or equal to 18, then
tt M2j ＝-0.5856M t +0.6971A ar -0.9151V daf +137.72 (formula 1)
Otherwise
tt M2j ＝-0.4505M t +0.5362A ar -0.7039V daf +105.84 (type 2)
This time of the volatile component V of the receiving group of the lignite ar ＝32.11>18, then tt M2j The calculation adopts formula (2), specifically as follows:
tt M2j ＝-0.4505×34.8+0.5362×3.14-0.7039×51.74+105.94＝55.53
the third step: determining the maximum allowable coal mill outlet temperature tt M2 The specific principle is as follows:
(1) If tt M2j >55, obtaining the powder manufacturing system design and calculation technical specification of DL/T5145-2012 thermal power plant at tt M2j Outlet dew point temperature t of lower coal mill dp (℃)
(1) If tt M2j ≥t dp +2, then tt M2 ＝tt M2j
(2) Otherwise tt M2j <t dp +2, then tt M2 ＝t dp +2
(2) If tt M2j Less 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/T5145-2012 thermal power plant dp55 (℃)。
①t dp55 Tt is determined when the number is less than or equal to 53 M2 ＝55
②t dp55 >53, then tt M2 ＝t dp55 +2
This time tt M2j ＝55.53>55, obtaining the product at tt according to DL/T5145-2012 Standard of computing technology for design of coal pulverizing System of thermal Power plant M2j Outlet dew point temperature t of lower coal mill dp =52, i.e. tt M2j ＝55.53≥t dp +2=52+2=54 belonging to the (1) th case of the (1) th case, and therefore the maximum allowable coal mill outlet temperature tt M2 ＝tt M2j =55.53 ℃. 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 present time is lower than the recommended guide rule, mainly considering that the coal is extremely high in explosiveness, and the lower temperature of the coal mill outlet 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 coals M2 Is determined
The first step is as follows: obtaining the total moisture M of the coal sample according to the related data t (%), and the base ash A ar (%), dry ashless base volatile V daf (%), the volatile fraction V of the recovered base ar (％)。
M of this brown coal t =14.7%, and a base ash content A was obtained ar =45.61%, dry ashless base volatile component V daf =51.05%, volatile component V of the received radical ar ＝20.26％
The second step is that: calculating theoretical maximum allowable temperature tt of coal mill outlet of coal type M2j (. Degree. C.), in particular, see formula (1) or (2)
If V ar Less than or equal to 18, then
tt M2j ＝-0.5856M t +0.6971A ar -0.9151V daf +137.72 (formula 1)
Otherwise
tt M2j ＝-0.4505M t +0.5362A ar -0.7039V daf +105.84 (formula 2)
This time, the volatile matter V of the receiving base of the high ash bituminous coal ar ＝20.26>18, then tt M2j The calculation adopts formula (2), specifically as follows:
tt M2j ＝-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 tt M2 The specific principle is as follows:
(1) If tt M2j >55, obtaining the product at tt according to DL/T5145-2012 Standard of computing technology for design of coal pulverizing System of thermal Power plant M2j Outlet dew point temperature t of lower coal mill dp (℃)
(1) If tt M2j ≥t dp +2, then tt M2 ＝tt M2j
(2) Otherwise tt M2j <t dp +2, then tt M2 ＝t dp +2
(2) If tt M2j Less 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/T5145-2012 thermal power plant dp55 (℃)。
①t dp55 Tt is determined when the number is less than or equal to 53 M2 ＝55
②t dp55 >53, then tt M2 ＝t dp55 +2
This time tt M2j ＝87.84>55, obtaining the powder manufacturing system design and calculation technical specification of DL/T5145-2012 thermal power plant at tt M2j Outlet dew point temperature t of lower coal mill dp =48 ℃ i.e. tt M2j ＝87.84≥t dp +2=48+2=50 for the (1) th case, and therefore the maximum allowable coal mill outlet temperature tt M2 ＝tt M2j =87.84 ℃. According to the regulations of DL/T466-2004 power station coal mill and powder making system model selection guide ruleThe maximum allowable outlet temperature is 60-70 ℃, the recommended value of the maximum allowable outlet temperature of the coal mill recommended in the present time is 18-28 ℃ higher than the recommended value of the export rule, mainly considering that although the volatile components of the coal are higher, the ash content is higher, and the explosion tendency of the coal powder is greatly reduced, so that the temperature of the outlet of the coal mill can be increased, the combustion stability can be enhanced, the cold air can be 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, it is intended that all such modifications and alterations be included within the scope of this invention as defined in the appended claims.
Claims (1)
1. A method of determining a maximum allowable coal mill outlet temperature, comprising the steps of:
1) Obtaining the total moisture, the received base ash content, the dried ash-free base volatile matter and the received base volatile matter of the coal sample; the expressions of total moisture, received base ash content, dry ash-free base volatile matter and received base volatile matter of the coal sample are respectively M t 、A ar 、V daf And V ar The units are all percent;
2) Calculating the theoretical maximum allowable temperature of the coal mill outlet of the coal type through the coal quality parameters; the expression of theoretical maximum allowable temperature of coal mill outlet of coal type is tt M2j In units of;
if V ar Less than or equal to 18, then
tt M2j =-0.5856M t +0.6971A ar -0.9151V daf +137.72 (formula 1)
If V ar Greater than 18, then
tt M2j =-0.4505M t +0.5362A ar -0.7039V daf +105.84 (formula 2)
3) Obtaining the final recommended maximum allowable temperature of the outlet of the coal mill according to the calculation result and the related conditions;
if tt M2j >55Obtaining the powder manufacturing system design and calculation technical specification of DL/T5145-2012 thermal power plant at tt M2j Outlet dew point temperature t of lower coal mill dp In units of;
if tt M2j ≥t dp +2, then tt M2 =tt M2j Otherwise tt M2j <t dp +2, then tt M2 =t dp +2；
If tt M2j Less 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/T5145-2012 thermal power plant dp55 In units of;
if t is dp55 Tt is determined when the number is less than or equal to 53 M2 =55, if t dp55 >53, then tt M2 =t dp55 +2。
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