阅读说明：本技术 Cfb锅炉物料循环倍率及分离器的分离效率的获取方法 (Method for acquiring circulating multiplying power of CFB boiler material and separation efficiency of separator ) 是由 时勇 李瑞波 王如超 聂志钢 刘化才 李海泉 于长深 商桂新 赵凤涛 黄秀平 王 于 2020-08-03 设计创作，主要内容包括：本发明公开了一种CFB锅炉物料循环倍率的获取方法,获取所述第一高度处的炉膛压力,获取所述第二高度处的炉膛压力,第一高度和第二高度相距H,其中,所述CFB锅炉的炉膛的设计流化风速值为V,H＝V×1s；计算得出所述第一高度处和所述第二高度处炉膛压力之间的差值ΔP；获取所述炉膛中的实际流化风速值V<Sub>1</Sub>,并通过公式K＝V<Sub>1</Sub>/V得到修正系数K；获取单位时间入炉煤量G<Sub>s</Sub>,根据公式G<Sub>c</Sub>＝K×F×ΔP/g,计算得出单位时间的物料循环量G<Sub>c</Sub>；由物料循环倍率公式R＝G<Sub>c</Sub>/G<Sub>s</Sub>计算得出物料循环倍率R。本发明能够更加准确的计算出锅炉物料循环倍率；本发明还公开了一种CFB锅炉分离器的分离效率的获取方法。(The invention discloses a method for acquiring material circulation multiplying power of a CFB (circulating fluid bed) boiler, which comprises the steps of acquiring the hearth pressure at a first height, acquiring the hearth pressure at a second height, and enabling the first height and the second height to be separated by a distance H, wherein the designed fluidizing air speed value of the hearth of the CFB boiler is V, and H is V multiplied by 1 s; calculating the difference value delta P between the furnace pressure at the first height and the furnace pressure at the second height; obtaining an actual fluidization wind speed value V in the hearth 1 And by the formula K ═ V 1 V, obtaining a correction coefficient K; obtaining the amount G of coal fed into the furnace in unit time s According to formula G c Calculating to obtain the material circulation amount G in unit time c (ii) a From materialsFormula of cyclic multiplying power R ═ G c /G s And calculating to obtain the material circulation ratio R. The method can more accurately calculate the material circulation rate of the boiler; the invention also discloses a method for acquiring the separation efficiency of the CFB boiler separator.)

1. A method for acquiring material circulation multiplying power of a CFB boiler is characterized by comprising the following steps:

acquiring the furnace pressure at a first height and the furnace pressure at a second height, wherein the height of the center of a furnace outlet is the first height; the height which is lower than the center of the hearth outlet and is at a vertical distance H from the center of the hearth outlet is a second height, the designed fluidizing air speed value of the hearth of the CFB boiler is V, and H is V multiplied by 1 s;

calculating the difference value delta P between the furnace pressure at the first height and the furnace pressure at the second height;

obtaining an actual fluidization wind speed value V between a first height and a second height in the hearth₁And by the formula K ═ V₁V, obtaining a correction coefficient K;

obtaining the amount G of coal fed into the furnace in unit time_sAccording to formula G_cCalculating to obtain the material circulation amount G in unit time_cWherein F is the cross-sectional area of the hearth, and g is the gravity acceleration; the formula of material circulation multiplying power R is G_c/G_sAnd calculating to obtain the material circulation ratio R.

2. The method for acquiring the material circulation rate of the CFB boiler according to claim 1, wherein the designed fluidization wind speed value V is 4.5-6 m/s.

3. The method for acquiring the material circulation rate of the CFB boiler according to claim 2, wherein the design fluidization wind speed value V is 5 m/s.

4. The method for acquiring material circulation rate of CFB boiler in accordance with claim 1,

more than two first pressure testing devices are arranged at the first height, and the average value of the pressures detected by all the first pressure testing devices is the furnace pressure at the first height;

and more than two second pressure testing devices are arranged on the second height, and the average value of the pressures detected by all the second pressure testing devices is the furnace pressure at the second height.

5. The method for acquiring material circulation rate of a CFB boiler according to claim 4, wherein if the furnace outlet is located on a front wall and/or a rear wall of the CFB boiler, the first pressure testing device and the second pressure testing device are arranged on a left wall and/or a right wall of the CFB boiler; the first pressure testing device and the second pressure testing device are arranged on a front wall and/or a rear wall of the CFB boiler if the furnace outlet is located on the left wall and/or the right wall of the CFB boiler.

6. The method for acquiring the material circulation rate of the CFB boiler according to claim 4, wherein the first pressure testing device and the second pressure testing device are arranged in a one-to-one correspondence manner in a vertical direction.

7. The method for acquiring the material circulation rate of the CFB boiler according to claim 6, wherein if the CFB boiler capacity is not more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 4-6; and if the capacity of the CFB boiler is more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 6-8.

8. The method for acquiring the material circulation rate of the CFB boiler according to claim 1, further comprising: from the formula c_pThe concentration c of the recycled material is obtained from K.DELTA.P/Hg_p。

9. The method for acquiring the material circulation rate of the CFB boiler according to any one of claims 1 to 8, wherein an actual value V of the fluidization wind speed between a first height and a second height in the hearth₁Measured by a wind speed sensor, or according to formula V₁＝VD_sjCalculated as/D, wherein D_sjThe actual load of the boiler and the rated load of the boiler are D.

10. A method for obtaining the separation efficiency of a CFB boiler separator is characterized by comprising the following steps:

the method for acquiring the material circulation multiplying power R of the CFB boiler according to any one of claims 1-9 is adopted to acquire the material circulation multiplying power R;

obtaining the part a of fly ash_fhObtaining the carbon content C of the fly ash_fhObtaining the received basal ash A_ar；

According to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) ) the separation efficiency η is calculated.

Technical Field

The invention relates to the technical field of boiler design and production, in particular to a method for acquiring material circulation multiplying power of a CFB boiler and separation efficiency of a separator.

Background

The CFB boiler is called a circulating fluidized bed boiler in English, and is called a circulating fluidized bed boiler in Chinese, and the circulating fluidized bed boiler has the advantages of wide coal variety adaptation, cleanness, environmental protection and the like, so the circulating fluidized bed boiler combustion technology becomes a clean coal combustion technology with good application prospect in the world.

The material circulation rate is an important parameter for the design and operation of the circulating fluidized bed, and has direct influence on the flow characteristic, combustion characteristic, heat transfer characteristic, variable working condition characteristic and the like of the material in the boiler, when the circulating fluidized bed boiler operates normally, the material entering the boiler and the material circulating in the boiler reach dynamic balance, the boiler has the material entering amount and the material circulating amount corresponding to the material entering amount and the material circulating amount at each working condition point, in order to express the material circulation rate quantitatively, the concept of circulation rate is introduced during the design of the boiler, and in the circulating fluidized bed boiler, the material circulation rate is the ratio of the material circulation rate to the coal entering amount in unit time.

The material circulation rate is an important technical index for the design and operation of the circulating fluidized bed boiler, and has important guiding significance for the selection and calculation of key parameters (such as combustion efficiency, separator separation efficiency, desulfurization efficiency, denitrification efficiency, fluidized air speed, bed temperature and the like) of the boiler. When the material circulation rate is increased, the heat transfer quantity of fine particles in the circulating material to a heating surface and the heat taken away from the dense-phase region are increased, so that the heat balance of the dense-phase region is facilitated, the bed temperature is effectively inhibited, and meanwhile, the low-nitrogen combustion atmosphere is created; when the material circulation rate is too small, the concentration of suspended fine particles on the upper part of the hearth is too small, the material quantity in the dense-phase region is increased, and the released heat is too much, so that the dense-phase region is over-heated and the load of the boiler is difficult to increase.

The problem that the measurement and calculation of the circulation multiplying power of the existing circulating fluidized bed boiler are not accurate enough is solved, and the selection and calculation of key parameters of the boiler are seriously influenced, so that how to accurately obtain the circulation multiplying power of the boiler material is a technical problem which needs to be solved urgently by technical personnel in the field at present.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for acquiring a material circulation ratio of a CFB boiler, so as to accurately measure the material circulation ratio of the circulating fluidized bed boiler during actual operation, and provide reference and guidance data for efficient and stable operation of the circulating fluidized bed boiler.

Another object of the present invention is to provide a method for obtaining separation efficiency of a separator of a CFB boiler.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for acquiring material circulation rate of a CFB boiler comprises the following steps:

acquiring the furnace pressure at a first height and the furnace pressure at a second height, wherein the height of the center of a furnace outlet is the first height; the height which is lower than the center of the hearth outlet and has a vertical distance H from the center of the hearth outlet is a second height, the designed fluidizing air speed value of the hearth of the CFB boiler is V, and H is V multiplied by 1 m;

calculating the difference value delta P between the furnace pressure at the first height and the furnace pressure at the second height;

obtaining an actual fluidization wind speed value V between a first height and a second height in the hearth₁And by the formula K ═ V₁V, obtaining a correction coefficient K;

obtaining the amount G of coal fed into the furnace in unit time_sAccording to formula G_cCalculating to obtain the material circulation amount G in unit time_cWherein F is the cross-sectional area of the hearth, and g is the gravity acceleration; the formula of material circulation multiplying power R is G_c/G_sAnd calculating to obtain the material circulation ratio R.

Preferably, the designed fluidization wind speed value V is 4.5 m/s-6 m/s.

Preferably, the design fluidization wind velocity value V is 5 m/s.

Preferably, more than two first pressure testing devices are arranged on the first height, and the average value of the pressures detected by all the first pressure testing devices is the furnace pressure at the first height;

and more than two second pressure testing devices are arranged on the second height, and the average value of the pressures detected by all the second pressure testing devices is the furnace pressure at the second height.

Preferably, the first pressure testing device and the second pressure testing device are arranged on a left wall and/or a right wall of the CFB boiler if the furnace outlet is located on a front wall and/or a rear wall of the CFB boiler; the first pressure testing device and the second pressure testing device are arranged on a front wall and/or a rear wall of the CFB boiler if the furnace outlet is located on the left wall and/or the right wall of the CFB boiler.

Preferably, the first pressure testing device and the second pressure testing device are arranged in a one-to-one correspondence in the vertical direction.

Preferably, if the capacity of the CFB boiler is not more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 4-6; and if the capacity of the CFB boiler is more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 6-8.

Preferably, from the formula c_pThe concentration c of the recycled material is obtained from K.DELTA.P/Hg_p。

Preferably, the actual value of the fluidization wind speed V between the first height and the second height in the furnace₁Measured by a wind speed sensor, or according to formula V₁＝VD_sjCalculated as/D, wherein D_sjThe actual load of the boiler and the rated load of the boiler are D.

The invention discloses a method for acquiring the separation efficiency of a CFB boiler separator, which comprises the following steps:

acquiring a material circulation multiplying power R by adopting any one of the CFB boiler material circulation multiplying power acquisition methods;

obtaining the part a of fly ash_fhObtaining the carbon content C of the fly ash_fhObtaining the received basal ash A_ar；

According to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) ) the separation efficiency η is calculated.

In the method for acquiring the material circulation multiplying power of the CFB boiler, the hearth pressures at a first height and a second height are measured, then the difference value of the hearth pressures at the first height and the second height is calculated, the actual fluidization wind speed value between the first height and the second height is acquired, the ratio of the actual fluidization wind speed value to the designed fluidization wind speed value is a correction coefficient, and the material circulation multiplying power is calculated by combining a formula with the correction coefficient;

the method for acquiring the material circulation multiplying power only needs to measure the furnace pressure values at the first height and the second height and the actual fluidization air speed values at the first height and the second height, the required measurement amount is small, the position of the first height is actually close to the center of the inlet of the separator, the measured pressure at the position can reflect the flue gas concentration value of the outlet of the furnace, and the material circulation multiplying power calculated by adopting the pressure value at the position is closer to the actual value, so the measurement precision of the actual circulation multiplying power of the circulating fluidized bed boiler is easy to guarantee; and the distance between the first height and the second height is the distance of flue gas running at the designed fluidization wind speed value in unit time under the rated working condition, the distance is about 5m generally, and compared with the measurement of the hearth pressure difference in the prior art, the measurement distance is greatly reduced, so that the accuracy of the pressure difference is improved, the calculated material circulation rate is closer to the true value, and the actual circulation rate of the circulating fluidized bed boiler can be reflected more truly.

The method for obtaining the separation efficiency adopts the material circulation multiplying power obtained by the method, and then the separation efficiency is obtained by calculation according to a formula.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic flow chart illustrating a method for obtaining material circulation rate of a CFB boiler disclosed in an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a CFB boiler disclosed in an embodiment of the present invention.

The drawings are numbered as follows:

1 is a hearth, 2 is a cyclone separator, 3 is a tail flue, 4 is a first height, and 5 is a second height.

Detailed Description

One of the cores of the invention is to provide a method for acquiring the material circulation rate of the CFB boiler, so that the material circulation rate of the circulating fluidized bed boiler in actual operation can be accurately measured, and reference and guidance data are provided for the efficient and stable operation of the circulating fluidized bed boiler.

Another core of the invention is to provide a method for obtaining the separation efficiency of the CFB boiler separator.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Please refer to fig. 1 and fig. 2, the method for obtaining the material circulation rate of the CFB boiler disclosed in the present embodiment includes:

acquiring furnace pressure at a first height and a second height, wherein in the embodiment, the height of a furnace outlet center is a first height, the height which is lower than the furnace outlet center and is vertically away from the furnace outlet center by H (in m) is a second height, if a design fluidizing air speed value of a furnace of the CFB boiler is V (in m/s), H is V × 1s, and H represents the distance that flue gas in the furnace flows according to the design fluidizing air speed in (1s) per unit time under a rated load working condition;

calculating the difference value delta P (in Pa) between the furnace pressure at the first height and the furnace pressure at the second height;

obtaining an actual fluidization wind speed value V between a first height and a second height in a hearth₁(in m/s) and is represented by the formula K ═ V₁V, obtaining a correction coefficient K;

obtaining the amount G of coal fed into the furnace in unit time_s(in kg/s) according to formula G_cCalculating to obtain the material circulation amount G in unit time_c(in kg/s), wherein F is the cross-sectional area of the furnace (in m)²) G is the acceleration of gravity; the formula of material circulation multiplying power R is G_c/G_sAnd calculating to obtain the material circulation ratio R.

According to the embodiment, in the method for acquiring the material circulation multiplying power of the CFB boiler, the hearth pressure at the first height and the hearth pressure at the second height are measured firstly, then the difference value of the hearth pressure at the first height and the hearth pressure at the second height is calculated, the actual fluidization wind speed value between the first height and the second height is acquired, the ratio of the actual fluidization wind speed value to the designed fluidization wind speed value is the correction coefficient, and the material circulation multiplying power is calculated by combining the formula with the correction coefficient;

the method for acquiring the material circulation multiplying power only needs to measure the furnace pressure values at the first height and the second height and the actual fluidization air speed values at the first height and the second height, the required measurement amount is small, the position of the first height is actually close to the center of the inlet of the separator, the measured pressure at the position can reflect the flue gas concentration value of the outlet of the furnace, and the material circulation multiplying power calculated by adopting the pressure value at the position is closer to the actual value, so the measurement precision of the actual circulation multiplying power of the circulating fluidized bed boiler is easy to guarantee; and the distance between the first height and the second height is the distance of flue gas running at the designed fluidization wind speed value in unit time under the rated working condition, the distance is about 5m generally, and compared with the measurement of the hearth pressure difference in the prior art, the measurement distance is greatly reduced, so that the accuracy of the pressure difference is improved, the calculated material circulation rate is closer to the true value, and the actual circulation rate of the circulating fluidized bed boiler can be reflected more truly.

It will be appreciated by those skilled in the art that the design fluidization wind velocity values for CFB boilers will vary depending on the capacity, and typically the design fluidization wind velocity value V will be in the range of 4.5m/s to 6m/s, preferably 5m/s (i.e. the average fluidization wind velocity at the upper part of the furnace at rated load), where H is 5 m.

In consideration of the accuracy of pressure value measurement, when a furnace outlet (flue gas outlet) is positioned on a front wall and/or a rear wall of the CFB boiler, the first pressure testing device and the second pressure testing device are arranged on a left wall and/or a right wall of the CFB boiler; the first pressure testing device and the second pressure testing device are arranged on the front wall and/or the rear wall of the CFB boiler if the furnace outlet is located on the left wall and/or the right wall of the CFB boiler.

The number of the first pressure testing devices and the second pressure testing devices is not limited, but it should be understood by those skilled in the art that if a plurality of first pressure testing devices and a plurality of second pressure testing devices are arranged and then the average value is taken, the average value is more accurate, so in this embodiment, the first pressure testing devices and the second pressure testing devices are arranged in one-to-one correspondence in the vertical direction, more than two first pressure testing devices are arranged at the first height, and the average value of data of all the first pressure testing devices is taken as the furnace pressure at the first height; and more than two second pressure testing devices are arranged on the second height, and the average value of the pressures detected by all the second pressure testing devices is the furnace pressure at the second height.

The cross-sectional areas of boilers with different capacities are different, so that the number of first pressure testing devices and the number of second pressure testing devices which need to be arranged are different, in the method for acquiring the material circulation multiplying power of the CFB boiler disclosed by the embodiment of the invention, if the capacity of the CFB boiler is not more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 4-6; and if the capacity of the CFB boiler is more than 240t/h, the number of the first pressure testing devices and the number of the second pressure testing devices are both 6-8.

Concentration of circulating material c_pActually, the method is also an important parameter that needs to be monitored during the operation of the boiler, and in this embodiment, the method for obtaining the material circulation rate further includes the following steps:

from the formula c_pThe concentration c of the recycled material is obtained from K.DELTA.P/Hg_p。

In an embodiment of the invention, the actual value of the fluidization wind speed V between the first level and the second level₁May be measured by a wind speed sensor arranged between the first level and the second level, and may also be according to formula V₁＝VD_sjCalculated as/D, wherein D_sjThe actual load of the boiler and the rated load of the boiler are D.

In addition, the invention also discloses a method for acquiring the separation efficiency of the CFB boiler separator, which comprises the following steps:

the method for acquiring the circulating multiplying power of the CFB boiler material disclosed in any one of the embodiments is adopted to acquire the circulating multiplying power R of the material, and the base ash A can be acquired through the analysis data of the coal as fired and the ash residue_ar(in percent), carbon content of fly ash C_fh(in percent) and the fly ash fraction a_fh(in percent) and then R/(R + a) according to the formula η ═ R_fh×A_ar/100(100-C_fh) ) the separation efficiency η is calculated.

According to the method for obtaining the separation efficiency, the method disclosed in the embodiment is adopted to obtain the material circulation multiplying power R, so that the separation efficiency of the separator obtained by calculating the material circulation multiplying power is more accurate and reliable.

The invention is further explained in detail by two practical operation examples:

practical working example 1

The CFB boiler with the capacity of 75t/h has the furnace sectional area F of 20m²The fly ash share a can be obtained according to the weighing of ash slag in the running process of the boiler_fh50 percent, the fly ash carbon content C can be obtained from ash sampling and testing data_fhThe content was 10%.

Table 1 actual operation example 1 part of the parameters

The boiler operates under the load working condition of 75t/h, the difference value delta P of the furnace pressure at the first height and the second height is 90Pa, and the actual fluidization wind speed value V₁Setting the fluidizing wind speed value V as 5m/s in rated load condition, and calculating the fluidizing wind speed value V according to the formula G_cThe material circulation amount G per unit time can be obtained by K × F × Δ P/G_c183.67kg/s, and is formed by a cyclic multiplying power formula R ═ G_c/G_sCalculating to obtain the material circulation multiplying power R of 48.34；

According to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) Calculating to obtain the separation efficiency of the separator to be 99.44%;

changing the operation condition, reducing the load of the boiler to 72t/h, setting the difference value delta P of the furnace pressure at the first height and the second height to 70Pa, and setting the actual fluidizing air speed value V₁4.8m/s, according to formula G_cThe material circulation amount G per unit time can be obtained by K × F × Δ P/G_c137.14kg/s, and is formed by a cyclic multiplying power formula R ═ G_c/G_sCalculating to obtain a material circulation multiplying power R of 36.09;

according to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) Calculated to give a separation efficiency of 99.25% for the separator.

Practical operation example 2

The CFB boiler with the capacity of 240t/h has the furnace sectional area F of 54m²The fly ash share a can be obtained according to the weighing of ash slag in the running process of the boiler_fh70 percent, the fly ash carbon content C can be obtained from ash sampling and testing data_fhThe content was 5%.

Table 2 actual operation example 2 part of the parameters

The boiler operates under the load working condition of 240t/h, the difference value delta P of the furnace pressure at the first height and the second height is 95Pa, and the actual fluidization wind speed value V₁5m/s, and the fluidizing wind speed value V is 5m/s according to the formula G under the designed rated load working condition_cThe material circulation amount G per unit time can be obtained by K × F × Δ P/G_c523.47kg/s, and is formed by a cyclic multiplying power formula R ═ G_c/G_sCalculating to obtain a material circulation multiplying power R of 36.53;

according to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) Calculating to obtain the separation efficiency of the separator to be 99.45%;

changing the operation condition, reducing the boiler load to 230t/h, ensuring that the difference value delta P of the furnace pressure at the first height and the second height is 80Pa, and actually fluidizingValue of wind velocity V₁4.8m/s, according to formula G_cThe material circulation amount G per unit time can be obtained by K × F × Δ P/G_c422.45kg/s, and is formed by a cyclic multiplying power formula R ═ G_c/G_sCalculating to obtain a material circulation ratio R of 29.48;

according to the formula eta ═ R/(R + a)_fh×A_ar/100(100-C_fh) Calculated to give a separation efficiency of the separator of 99.30%.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.