CN111812057B - Biomass co-combustion ratio on-line monitoring system based on stable carbon isotope and analysis method - Google Patents

Abstract

An online biomass co-combustion ratio monitoring system and an analysis method based on stable carbon isotopes are characterized in that flue gas is taken from a flue of a coal and biomass co-combustion boiler to be cooled and dedusted, and stable carbon isotope ratio delta of the mixed flue gas is measured by adopting infrared laser detection equipment in stable carbon isotopes ¹³ C, the testing error of the equipment is only +/-0.025 thousandths, the equipment is not influenced by water content, and the equipment cost is far lower than that of the equipment ¹⁴ And C, an online analysis device, which has economic competitiveness. Establishing linear regression equation fitting goodness of fit R obtained by correcting carbon content or calorific value by using online analysis method ² >And 0.99, judging that the error of the biomass co-combustion ratio is controlled within 2.0 percent, and monitoring the change of the biomass co-combustion ratio in real time. The invention can accurately monitor the biomass blending combustion ratio in real time, provides technical support for the formulation and implementation of a policy of subsidy of biomass usage amount, and can also be used for carbon emission monitoring and carbon trading markets.

Description

On-line monitoring system and analysis method of biomass blending ratio based on stable carbon isotope

technical field

The invention relates to the establishment of a real-time on-line detection method for establishing a real-time on-line detection method for using a stable carbon isotope mid-infrared laser device to monitor the δ ¹³ C value in the co-combustion flue gas of coal and biomass to determine the biomass blending ratio, and belongs to the field of isotope detection and boiler combustion technology detection .

Background technique

Biomass energy is a clean and renewable energy. In recent years, biomass power generation has gradually emerged. Using biomass to replace fossil fuels for power generation can effectively reduce CO ₂ and SO ₂ emissions. Biomass and coal mixed combustion power generation has been included in the national industrial plan, and electricity price subsidies should be provided for the biomass power generation part, which involves the measurement of biomass electricity, but the scientific and fair online detection of biomass is still coal-fired biomass coupled power generation The biggest problem facing existing technology. The detection of the proportion of biomass fuel can be divided into front-end detection and back-end detection according to the different collection and detection positions. Co-combustion power generation has achieved great development in the EU, but the current methods mostly use front-end detection, and there are many tests, Disadvantages such as many calculations, many reports, and labor consumption. Currently more advanced back-end detection methods mainly include SO ₂ concentration detection method and ¹⁴ C content detection method. Because biomass contains some alkali metals, which will react with S, affecting the monitoring results of SO ₂ concentration; the natural abundance of ¹⁴ C is too low, which requires extremely high equipment precision, so the accuracy and reliability of the ¹⁴ C content detection method is still At the exploratory stage, at the same time, ^14C technology mostly uses flue gas side sampling for laboratory analysis, and the analytical equipment used is mostly expensive nuclear magnetic, mass spectrometry and other precision instruments, which limits the popularization and application of biomass application amount back-end detection technology . The public master thesis (Biomass co-combustion power generation co-combustion ratio detection and fine particle removal technology research, Mei Kaiyuan, Tsinghua University, 2015) reported that the laboratory accelerated mass spectrometer (AMS) can judge the biomass by off-line test of ¹⁴ C concentration. The error of blending ratio is 10~16%. Therefore, the research and development of rapid and accurate detection equipment suitable for the application of biomass in the industry can provide technical support for the implementation of government subsidy policies.

At present, the back-end detection of biomass application needs to solve the problems of real-time detection and expensive equipment. Mid-infrared laser isotope detection technology can realize fast and real-time detection of stable carbon isotope ratio δ ¹³ C ( ¹³ CO ₂ / ¹² CO ₂ ). The δ ¹³ C values of biomass and coal are significantly different, and the blending ratio of coal and biomass can be detected based on the difference in δ ¹³ C values. At the same time, the cost of mid-infrared laser isotope detection equipment is relatively low, and it has been successfully used in oil and gas field exploration. The existing carbon isotope mid-infrared laser detection equipment is based on the continuous maturity and development of quantum cascade laser design and development of a set of multi-channel optical detection core devices. It greatly reduces the difficulty of installation and maintenance of mid- and far-infrared laser detection instruments, and can quickly replace laser detectors to meet the needs of instruments with different wavelengths, and realize the replacement of expensive equipment such as mass spectrometry, but the corresponding evaluation methods are still blank at home and abroad . Therefore, it is very important to establish a real-time online detection and analysis method based on stable carbon isotope mid-infrared laser detection equipment to monitor the biomass blending ratio, which can provide technical support for the implementation of government subsidy policies. At the same time, this method can be used in carbon emissions and carbon trading markets. Promote the healthy and orderly development of clean energy.

Contents of the invention

The present invention proposes a system and analysis method for online monitoring of biomass blending ratio based on stable carbon isotopes, so as to realize real-time online detection of biomass blending ratio, and the error is controlled within 2.0%.

The technical scheme of the present invention is as follows: a system and analysis method for real-time monitoring of biomass blending ratio based on stable carbon isotope, characterized in that: the system includes flue gas online sampling channel, condenser, filter, back pressure valve, carbon isotope Mid-infrared laser detection equipment.

The carbon isotope mid-infrared laser detector mainly includes a quantum cascade laser, a hollow waveguide and a mid-infrared laser detector. The hollow waveguide contains a multi-channel optical path, a laser inlet, and a gas inlet/outlet. The mixed flue gas enters the multi-channel optical system in the hollow waveguide through the air inlet. In the spectrum, the quantum cascade laser emits mid-infrared laser, and the mid-infrared laser interacts with the carbon dioxide gas molecules in the hollow waveguide, according to Lambert-Beer's law The infrared laser is absorbed by the carbon dioxide gas molecules, and the absorption spectrum receives the signal through the detector to measure the absorption value of the carbon isotope. The carbon isotope mid-infrared laser detector can measure multiple spectral absorption peaks by measuring the absorption spectrum, of which the two main absorption peaks are ^{the 13} CO ₂ absorption peak on the left and ^{the 12} CO ₂ absorption peak on the right. The contained isotope ratio δ ¹³ C ( ¹³ C/ ¹² C), can give its isotope value in real time. The carbon isotope mid-infrared laser detection device is an analyzer for accurately measuring the carbon element content and stable isotope value ( ¹² C/ ¹³ C) in various carbon-containing components. The carbon isotope analyzer creatively uses a number of advanced optical measurement technologies - mid-infrared quantum cascade laser (QCL) and hollow waveguide (HWG), to achieve high-precision laser carbon isotope measurement. QCL is a unipolar semiconductor laser based on electronic transitions between semiconductor-coupled quantum well subbands. Its working principle is completely different from conventional semiconductor lasers. It breaks the electron-hole recombination stimulated emission mechanism of traditional pn junction semiconductor lasers. The particle population inversion generated between the separated electronic states caused by the quantum confinement effect in the semiconductor heterojunction thin layer realizes single electron injection and multi-photon output. QCL has the advantages of small size, simple operation, low price, and low sensitivity to the environment.

The present invention is also characterized by: a back pressure valve is installed before the carbon isotope mid-infrared laser detection equipment, which can realize continuous sampling; the carbon isotope mid-infrared laser detection device can simultaneously detect ¹² CO ₂ , ¹³ CO ₂ stable carbon isotope values .

The present invention provides a system and analysis method based on stable carbon isotopes for on-line monitoring of biomass co-combustion ratio, which is characterized in that: the flue gas taken online from boilers co-combusting coal and biomass is a mixture containing ¹² CO ₂ and ¹³ CO ₂ The gas is passed into a carbon isotope mid-infrared laser detection device for stable carbon isotope analysis. The stable carbon isotope mid-infrared laser detection device can directly measure the carbon isotope ratio δ ¹³ C ( ¹³ C/ ¹² C) of the mixed flue gas.

The carbon isotope ratio δ ¹³ C ( ¹³ C/ ¹² C) detected by the carbon isotope mid-infrared laser detection equipment is defined according to the following formula:

δ ¹³ C = [(Rp/Rs-1)]×1000

In the formula, Rp is the ratio of heavy to light isotope abundance of carbon in the sample ( ¹³ Cp/ ¹² Cp ), and Rs is the ratio of heavy to light isotope abundance of the international common standard ( ¹³ Cs/ ¹² Cs).

The stable carbon isotope mid-infrared laser detection equipment can directly test the carbon isotope ratio δ ¹³ C of the mixed flue gas. There are significant differences between the δ ¹³ C values of different coal samples and different biomasses. According to the δ ¹³ C difference The linear regression equation can be obtained after correcting the carbon content of coal and biomass, which is used to calculate the blending ratio of biomass in co-combustion materials:

In the formula (1), y is the δ ¹³ C value displayed by the carbon isotope laser detection equipment, x is the biomass blending ratio after the carbon content correction, and the interference factors such as moisture, ash, and volatile matter can be excluded after the carbon content correction , a is the slope of the linear regression equation obtained by co-combustion of different coal types and different biomass, b is the δ ¹³ C value of the coal sample; in the formula (2), r is the biomass without carbon content correction Material blending ratio, C _C is the carbon content of the coal sample, and C _B is the carbon content of the biomass.

The stable carbon isotope mid-infrared laser detection equipment can directly test the carbon isotope ratio δ ¹³ C of the mixed flue gas, and there are significant differences between the δ ¹³ C values of different coal samples and different biomass, and the coal and biomass can be used After the heat is corrected, a linear regression equation is obtained, which is used to judge the blending ratio of biomass:

In formula (3), y is the δ ¹³ C value displayed by the carbon isotope laser detection equipment, x ₁ is the biomass blending ratio corrected by calorific value, and a ₁ is the co-combustion ratio of different coal types and different biomass The slope of the obtained linear regression equation, b is the δ ¹³ C value of the coal sample, which can eliminate the influence of moisture, ash, volatiles and other interfering factors after calorific value correction; in formula (4), r ₁ is the value without calorific value correction The biomass blending ratio, Q _C is the calorific value of the coal sample, and Q _B is the calorific value of the biomass.

In the above method of the present invention, it is characterized in that: the error of the stable carbon isotope online detection equipment is only ±0.025‰, the goodness-of-fit of the linear regression equation y=ax+b R ² >0.99, and the test biomass blending ratio (such as 20%) the error range is controlled within 2.0%.

The present invention has the following advantages and outstanding effects: (1) The test error of the stable carbon isotope mid-infrared laser detection equipment is only ±0.025‰, and the obtained carbon isotope ratio δ ¹³ C is not disturbed by water content, ash content, volatile matter, etc., and the equipment The cost is much lower than ¹⁴ C online analysis equipment, simple, practical, portable, and economically competitive; (2) The establishment of an online analysis method can monitor the biomass mixing ratio in real time, and the linear regression obtained by fitting after carbon content correction or calorific value correction The equation y= ax+b or y=a ₁ x ₁ +b has a goodness of fit R ² >0.99, and the error range of judging the biomass blending ratio (such as 20%) is controlled within 2.0%, and the accuracy is good; (3 ) The online analysis method of the present invention is suitable for the co-combustion detection of various coals and biomass, and is less limited by the type of raw materials; at the same time, the analysis method obtained by correcting the carbon content can be used for carbon emission monitoring and carbon trading market; (4) after calorific value correction The obtained linear regression equation y=a ₁ x ₁ +b can provide important reference data for the power generation obtained by burning biomass in power plants; If there is a difference, it can be inferred that there is more water content in the biomass or there is adulteration.

Description of drawings

Fig. 1 is a schematic diagram of the connection of the sampling test system according to the embodiment of the present invention. Figure 2 is the multi-pass to coupling optical system of the mid-infrared laser. Fig. 3 is a measurement schematic diagram of the carbon isotope measuring instrument used in the present invention. Fig. 4 is a fitting linear relationship obtained after carbon content correction in Example 3 of the present invention. Fig. 5 is a fitting linear relationship obtained after calorific value correction in Example 3 of the present invention. Fig. 6 is a fitting linear relationship obtained after carbon content correction in Example 5 of the present invention. Fig. 7 is a fitting linear relational expression obtained after calorific value correction in Example 5 of the present invention. Fig. 8 is a fitting linear relationship obtained after carbon content correction in Example 7 of the present invention. Fig. 9 is a fitting linear relational expression obtained after calorific value correction in Example 7 of the present invention.

Fig. 10 is a fitting linear relationship obtained after carbon content correction in Example 8 of the present invention. Fig. 11 is a fitting linear relationship obtained after calorific value correction in Example 8 of the present invention. Fig. 12 is the linear relationship obtained in Example 9 of the present invention. Fig. 13 is a fitting linear relationship obtained after carbon content correction in Example 12 of the present invention. Fig. 14 is a fitting linear relational expression obtained after calorific value correction in Example 12 of the present invention. Fig. 15 is a fitting linear relationship obtained after carbon content correction in Example 13 of the present invention. Fig. 16 is a fitting linear relationship obtained after calorific value correction in Example 13 of the present invention.

In the figure: 1-boiler; 2-flue gas channel; 3-sampling channel; 4-condenser; 5-filter; 6-back pressure valve; 7-carbon isotope mid-infrared laser detection equipment.

Detailed ways

In order to make the monitoring system, real-time online analysis method and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The invention discloses a system and analysis method based on stable carbon isotopes for real-time monitoring of biomass co-fuel ratio. Sampling channel 3, condenser 4, filter 5, back pressure valve 6, carbon isotope mid-infrared laser detector 7. Among them, the carbon isotope mid-infrared laser detector 7 is the flue gas produced by the mixed combustion of coal and biomass in the boiler, which passes through the flue sampling channel in sequence, and then enters the carbon isotope laser detection equipment to obtain δ ¹³ C The value ( ¹³ CO ₂ / ¹² CO ₂ ) is brought into the calculation formula (1) and (3) to obtain the biomass mixed combustion ratio.

The carbon isotope mid-infrared laser detector mainly includes a quantum cascade laser (AdTech, USA), a hollow waveguide and a mid-infrared laser detector (THORLABS, DET10A/M). /export, as shown in Figure 2.

The process of detecting the carbon isotope ratio of the flue gas by the carbon isotope measuring instrument is as follows: the mixed flue gas enters the multi-channel optical system in the hollow waveguide through the air inlet, and the quantum cascade laser emits the mid-infrared laser in the spectrum, and the mid-infrared laser passes through the hollow waveguide and the Among them, the carbon dioxide gas molecules interact, and the infrared laser is absorbed by the carbon dioxide gas molecules according to Lambert-Beer's law, and the absorption spectrum receives the signal through the detector to measure the absorption value of the carbon isotope. The measurement diagram of the carbon isotope measuring instrument is shown in Figure 3. By measuring the absorption spectrum, multiple spectral absorption peaks can be measured, and the two main absorption peaks are ^{the 13} CO ₂ absorption peak on the left and ^{the 12} CO ₂ absorption peak on the right as shown in Figure 3 For the absorption peak, the isotope ratio δ ¹³ C ( ¹³ C/ ¹² C) contained in the carbon dioxide gas can be obtained from the area of the absorption peak, and the isotope value can be given in real time.

The industrial analysis, element analysis and calorific value determination of seven samples of Shanxi coal, Inner Mongolia coal, Guizhou coal, corn straw, cotton straw, wood chips and rice husk are shown in Table 1. The real-time online analysis method of the present invention will be further described below by co-combusting different coal samples (Shanxi coal, Inner Mongolia coal, Guizhou coal) and different biomass types (corn stalks, cotton stalks, wood chips, rice husks), but the present invention is not subject to limitations of these examples.

Embodiment 1: The method for online detection of coal sample δ ¹³ C value by a carbon isotope mid-infrared laser detector, which includes the following steps: adding pure Shanxi coal into a boiler for full combustion, which can be obtained from the sampling pipeline of the flue in real time during the combustion process The flue gas passes through the condenser, the filter _, the back ^pressure valve, and finally the carbon isotope mid-infrared laser detection equipment to measure the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas. The isotope peak area difference of ¹² CO ₂ was used to obtain the carbon isotope δ ¹³ C value of Shanxi coal. After correcting the standard CO ₂ carbon isotope δ ¹³ C value, the δ ¹³ C value of Shanxi coal was -20.61.

Embodiment 2: The method for online detection of biomass δ ¹³ C value by carbon isotope mid-infrared laser detector, which includes the following steps: carbon isotope mid-infrared laser detector on-line detection of δ ¹³ C value of coal sample, adding pure corn stalks to the boiler Carry out full combustion. During the combustion process, the flue gas can be obtained from the sampling pipe of the flue in real time, passing through the condenser, filter and back pressure valve in sequence, and finally measured by the carbon isotope mid-infrared laser detection equipment to obtain ^{the 13} CO ₂ , The spectral absorption peak area of ¹² CO ₂ is compared with the isotope peak area difference of ¹³ CO ₂ and ¹² CO ₂ to obtain the carbon isotope δ ¹³ C value of corn straw. After correcting the standard CO ₂ carbon isotope δ ¹³ C value, the corn straw is obtained δ ¹³ C value of -11.91.

Embodiment 3: The method for on-line monitoring of the biomass blending ratio by a carbon isotope mid-infrared laser detector, which includes the following steps: adding Shanxi coal and corn stalks with different blending ratios to the boiler for full combustion, wherein the blending of corn stalks The ratio is 2.5%, 5%, 7.5%, 10%, 15%, 20%, 25% and 30%. During the combustion process, the flue gas can be obtained from the sampling pipe of the flue in real time, and then pass through the condenser, filter and back pressure valve, and finally the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas were measured by the carbon isotope mid-infrared laser detection equipment, and compared with the isotope peak area differences of ¹³ CO ₂ and ¹² CO ₂ , the Shanxi coal and The carbon isotope δ ¹³ C value of corn straw is corrected by the standard CO ₂ carbon isotope δ ¹³ C value, and the δ ¹³ C values of different corn straw blending ratios are: -21.4, -21.224, -21.09, -20.91 , -20.68, -20.32, -19.95, -19.56. The biomass blending ratio after carbon content correction is: 1.41%, 2.86%, 4.33%, 5.84%, 8.97%, 12.25%, 15.69%, 19.31%, take this as the abscissa to obtain the corresponding δ ¹³ C value Draw a graph for the ordinate, and get a linear equation after linear fitting, as shown in Figure 4, the fitting linear relationship formula for the blending of Shanxi coal and corn stalks in different proportions is y= 0.1x-21.55 (wherein x is raw The blending ratio of the substance after carbon content correction, y is the carbon isotope δ ¹³ C value), and the goodness of fit R ² =0.997, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of coal and corn stalk combustion ratio in Shanxi, when the corn stalk burning ratio is 20%, the error range is 2.0%.

In addition, the biomass blending ratio can also be judged by heat correction. The biomass blending ratio is corrected by calorific value: 1.44%, 2.91%, 4.41%, 5.95%, 9.13%, 12.46%, 15.95%, 19.61 %, take this as the abscissa to obtain the corresponding δ ¹³ C value and draw the ordinate, and get the linear equation after linear fitting, as shown in Figure 5, the simulated mixture of Shanxi coal and corn stalks in different proportions is obtained. The linear relationship is y= 0.1x-21.55 (where x is the blending ratio of biomass corrected by calorific value, and y is the carbon isotope δ ¹³ C value), and the goodness of fit R ² =0.9973, which shows that the relationship The linear relationship is better. Using this relational formula to analyze the error degree of coal and corn stalk combustion ratio in Shanxi, when the corn stalk burning ratio is 20%, the error range is 1.9%.

Comparing the linear equations obtained after correction of carbon content and calorific value, it can be seen that the two correction methods can obtain the true functional relationship between the biomass blending ratio and the carbon isotope ratio, and the error analysis is similar.

Embodiment 4: The method for on-line monitoring of the biomass blending ratio by a carbon isotope mid-infrared laser detector, which includes the following steps: adding pure cotton stalks to the boiler for full combustion, which can be obtained from the sampling pipe of the flue in real time during the combustion process The flue gas passes through the condenser, filter and back pressure valve in sequence, and finally the carbon isotope mid-infrared laser detection equipment measures the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas, comparing ^{the 13} CO ₂ and ¹² CO ₂ , the carbon isotope δ ¹³ C value of cotton straw was obtained. After correcting the standard CO ₂ carbon isotope δ ¹³ C value, the δ ¹³ C value of cotton straw was -26.09.

Embodiment 5: The method for on-line monitoring of biomass blending ratio by carbon isotope mid-infrared laser detector, which includes the following steps: adding Shanxi coal and cotton stalks with different blending ratios to the boiler for full combustion, wherein the blending of cotton stalks The ratios are 5%, 10%, 20% and 30%, and the similarities with Example 3 will not be repeated. The difference is that the δ ¹³ C values of different cotton straw blending ratios are -21.88, -22.14, -21.88, -22.14, - 22.60, -23.25, the blending ratio is 3.09%, 6.31%, 13.16%, 20.62% after correcting the carbon content, take this as the abscissa to obtain the corresponding δ ¹³ C value for the ordinate to plot, and linearly simulate After the combination, the linear equation is obtained, as shown in Figure 6, the fitted linear relational expression of the blending of Shanxi coal and cotton straw in different proportions is y = -0.0781x-21.62, and the goodness of fit R ² =0.996, indicating that the relational expression The linear relationship is better. Using this relational formula to analyze the error degree of coal and cotton straw combustion ratio in Shanxi, when the mixed combustion ratio of cotton straw is 20%, the error range is 1.0%. At the same time, the blending ratios corrected by calorific value are 3.12%, 6.36%, 13.26%, and 20.76%, and the linear fitting equation obtained by plotting is y =-0.0777x-21.61, as shown in Figure 7, the goodness of fit R ² =0.996, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of Shanxi coal and cotton straw combustion ratio, when the cotton straw burning ratio is 20%, the error range is 0.8%. The linear equation obtained after correction of carbon content and calorific value is similar, the true functional relationship between biomass blending ratio and carbon isotope ratio, and the error analysis is similar.

Embodiment 6: The method for online detection of biomass δ ¹³ C value by a carbon isotope mid-infrared laser detector, which includes the following steps: adding pure wood chips to the boiler for full combustion, and can obtain smoke from the sampling pipe of the flue in real time during the combustion process. The gas passes through the condenser, filter and back pressure valve in turn, and finally the carbon isotope mid-infrared laser detection equipment measures the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas, comparing ^{the 13} CO ₂ and ¹² CO ₂ The carbon isotope δ ¹³ C value ^of wood ^chips was obtained by the difference of _isotope peak area of .

Embodiment 7: the carbon isotope mid-infrared laser detector on-line monitors the method for biomass blending ratio, it comprises the following steps: adding Shanxi coal and wood chips of different blending ratios to the boiler for full combustion, wherein the blending ratio of wood chips is 5%, 10%, 20% and 30%, the same as Example 3 will not be repeated, the difference is: the δ ¹³ C values of different sawdust blending ratios are -21.84, -22.16, -22.60, - 23.20, the blending ratio is 3.14%, 6.40%, 13.34%, and 20.88% after carbon content correction, which is used as the abscissa to obtain the corresponding δ ¹³ C value and plotted on the ordinate, and obtained after linear fitting The linear equation, as shown in Figure 8, shows that the fitting linear relational expression of Shanxi coal mixed with different proportions of sawdust is y = -0.077x-21.62, and the goodness of fit R ² =0.995, indicating that the linear relational expression of this relational expression is relatively good. Using this relational formula to analyze the error degree of Shanxi coal and wood chip combustion ratio, when the wood chip combustion ratio is 20%, the error range is 1.0%. At the same time, the blending ratios corrected by calorific value are 3.20%, 6.52%, 13.57%, and 21.21%, and the linear fitting equation obtained by plotting is y = -0.0762x-21.62, as shown in Figure 9, the goodness of fit R ² =0.995, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of Shanxi coal and wood chip combustion ratio, when the wood chip combustion ratio is 20%, the error range is 1.0%. The comparison shows that the linear equation obtained after correction of carbon content and calorific value is similar, the true functional relationship between the biomass blending ratio and the carbon isotope ratio, and the error analysis is similar.

Embodiment 8: The method for on-line monitoring of the biomass blending ratio by a carbon isotope mid-infrared laser detector, which includes the following steps: adding Shanxi coal, cotton stalks and wood chips to the boiler for full combustion, wherein the joint blending of cotton stalks and wood chips The mixing ratio is 5%, 10%, 20% and 30% (the two are equally divided according to the mixing ratio), and the same part as embodiment 3 is not repeated, and the difference is: obtain the δ ¹³ of different sawdust mixing ratios C values are -21.85, -22.08, -22.6, -23.15, and the blending ratios are 3.11%, 6.36%, 13.25%, 20.75% after carbon content correction. Take this as the abscissa to obtain the corresponding δ ¹³ C values As shown in Figure 10, the fitting linear relationship between Shanxi coal and biomass (cotton straw, wood chips) with different blending ratios is y = -0.0744x-21.61, and the goodness of fit is R ² =0.998, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of Shanxi coal and sawdust combustion ratio, when the biomass blending ratio is 20%, the error range is 2.0%. At the same time, the blending ratios corrected by calorific value are 3.16%, 6.44%, 13.41%, and 20.99%, and the linear fitting equation obtained by plotting is y = -0.07365x-21.6, as shown in Figure 11, the goodness of fit R ² =0.999, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of coal and sawdust combustion ratio in Shanxi, when the biomass blending ratio is 20%, the error range is 1.9%. The comparison shows that the linear equation obtained after correction of carbon content and calorific value is similar, the true functional relationship between the biomass blending ratio and the carbon isotope ratio, and the error analysis is similar.

Embodiment 9: The method for on-line monitoring of biomass blending ratio by carbon isotope mid-infrared laser detector, which comprises the following steps: adding Shanxi coal and 20% blending ratio of cotton stalks and sawdust to the boiler for full combustion, wherein cotton The mixing ratio of straw and wood chips is 0% wood chips + 20% cotton straw, 5% wood chips + 15% cotton straw, 10% wood chips + 10% cotton straw, 15% wood chips + 5% cotton straw, 20% wood chips + 0% Cotton stalks, the same as Example 3 will not be repeated, the difference is: the δ ¹³ C values of different sawdust blending ratios are -22.5, -22.6, -22.6, -22.6, with the blending ratio as the abscissa, Obtaining the corresponding δ ¹³ C values and drawing on the ordinate, as shown in Figure 12, the fitting linear relationship between Shanxi coal and cotton straw and sawdust with different blending ratios is almost a straight line, indicating that coal can be mixed with various Biomass is co-combusted, and the carbon isotope δ ¹³ C value of the resulting mixture has nothing to do with the ratio of various biomasses. The error degree analysis shows that when the biomass mixed combustion ratio is 20%, the error range is 1.8%. Further analysis shows that the carbon isotope monitoring system and analysis method of the present invention are suitable for the co-combustion of coal samples and different proportions of biomass, and the total blending ratio of the obtained biomass is hardly affected by the change of the blending ratio of the two biomasses. .

Embodiment 10: A method for on-line detection of coal sample δ ¹³ C value by a carbon isotope mid-infrared laser detector, which includes the following steps: adding pure Guizhou coal into a boiler for full combustion, which can be obtained from the sampling pipe of the flue in real time during the combustion process The flue gas passes through the condenser, the filter _, the back ^pressure valve, and finally the carbon isotope mid-infrared laser detection equipment to measure the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas. The isotope peak area difference of ¹² CO ₂ was used to obtain the carbon isotope δ ¹³ C value of Guizhou coal. After correcting the standard CO ₂ carbon isotope δ ¹³ C value, the δ ¹³ C value of Guizhou coal was -21.01.

Embodiment 11: A method for on-line detection of coal sample δ ¹³ C value by a carbon isotope mid-infrared laser detector, which includes the following steps: adding pure Inner Mongolia coal to the boiler for full combustion, which can be obtained from the sampling pipe of the flue in real time during the combustion process The flue gas passes through the condenser, the filter _, the back ^pressure valve, and finally the carbon isotope mid-infrared laser detection equipment to measure the spectral absorption peak areas of ¹³ CO ₂ and ¹² CO ₂ contained in the mixed gas. The isotope peak area difference of ¹² CO ₂ was used to obtain the carbon isotope δ ¹³ C value of Inner Mongolia coal. After correcting the standard CO ₂ carbon isotope δ ¹³ C value, the δ ¹³ C value of Inner Mongolia coal was -21.91.

Embodiment 12: A method for online monitoring of the biomass blending ratio by a carbon isotope mid-infrared laser detector, which includes the following steps: adding Guizhou coal and corn stalks with different blending ratios to the boiler for full combustion, wherein the blending of corn stalks The ratios are 5%, 10%, 20% and 30%, and the similarities with Example 3 will not be repeated, the difference is that the δ ¹³ C values of different corn stalk blending ratios are -20.77, -20.38, -20.77, -20.38, - 19.78, -19.05, the blending ratio is 3.17%, 6.47%, 13.47%, 21.06% after the carbon content is corrected, take this as the abscissa to obtain the corresponding δ ¹³ C value and draw the ordinate, as shown in Figure 13 As shown, the fitting linear relationship between Guizhou coal and different proportions of corn stalks is y = 0.095x-21.0, and the goodness of fit R ² =0.998, indicating that the linear relationship of the relationship is better. The degree of error was analyzed for the combustion ratio of coal and corn stalks in Guizhou based on this relational expression. When the mixed combustion ratio of corn stalks was 20%, the error range was 0.5%. At the same time, the blending ratios corrected by calorific value are 3.19%, 6.50%, 13.52%, and 21.14%, and the linear fitting equation obtained by plotting is y = 0.095x-21.05, as shown in Figure 14, the goodness of fit R ² =0.998, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of coal and corn stalk combustion ratio in Guizhou, when the corn stalk burning ratio is 20%, the error range is 0.7%. The comparison shows that the linear equation obtained after correction of carbon content and calorific value is similar, the true functional relationship between the biomass blending ratio and the carbon isotope ratio, and the error analysis is similar.

Embodiment 13: A method for online monitoring of the biomass blending ratio by a carbon isotope mid-infrared laser detector, which includes the following steps: adding Inner Mongolia coal and corn stalks with different blending ratios to the boiler for full combustion, wherein the blending of corn stalks The ratios are 5%, 10%, 20% and 30%, and the similarities with Example 3 will not be repeated, the difference is that the δ ¹³ C values of different corn stalk blending ratios are -21.65, -21.36, -21.65, -21.36, - 20.81, -20.14, the blending ratio after carbon content correction is 3.17%, 6.47%, 13.47%, 21.06%, take this as the abscissa to obtain the corresponding δ ¹³ C value for the ordinate, as shown in Figure 15 As shown, the fitting linear relational expression of the blending of Inner Mongolia coal and different proportions of corn stalks is y = 0.9048x-21.905, and the goodness of fit R ² =0.999, indicating that the linear relational expression of the relational expression is better. Using this relational formula to analyze the error degree of the combustion ratio of coal and corn stalks in Inner Mongolia, when the mixed combustion ratio of corn stalks is 20%, the error range is 0.5%. At the same time, the blending ratios corrected by calorific value are 2.84%, 5.81%, 12.19%, and 19.23%, and the linear fitting equation obtained by plotting is y = 0.912x-21.904, as shown in Figure 16, and the goodness of fit is R ² =0.999, indicating that the linear relationship of the relationship is better. Using this relational formula to analyze the error degree of the combustion ratio of coal and corn stalks in Inner Mongolia, when the mixed combustion ratio of corn stalks is 20%, the error range is 0.2%. The comparison found that the linear equation obtained after correction of carbon content and calorific value was similar, and the true functional relationship between biomass blending ratio and carbon isotope ratio, and the error of biomass blending ratio after correction of calorific value was lower.

Embodiments 3, 5, and 7 of the present invention relate to the co-combustion of Shanxi coal and a single biomass respectively. The biomass involves three types of corn stalks, cotton stalks and sawdust, and the carbon isotope δ ¹³ C value is obtained through carbon isotope laser detection equipment. Taking the biomass co-combustion ratio (0-30%) as the abscissa, and the carbon isotope δ ¹³ C value of the mixed flue gas as the ordinate, the linear regression was obtained after correction by the carbon content or calorific value of Shanxi coal and different biomass respectively Equation, its goodness of fit R ² >0.99, indicating that the linear relationship between the two is good, when the biomass blending ratio is 20%, the error range of judging the biomass blending ratio is within 2.0%, compared with the current existing technology The accuracy has been greatly improved. Therefore, the real-time on-line detection and analysis method of the stable carbon isotope involved in the present invention has higher accuracy in determining the blending ratio of biomass.

Embodiments 8 and 9 of the present invention involve co-combustion of Shanxi coal with cotton stalks and wood chips at the same time. The carbon isotope δ ¹³ C value (ordinate) of the mixed flue gas was obtained by the carbon isotope laser detection equipment, and the goodness of fit of the linear regression equation was obtained R ² >0.99; the total mixed combustion ratio of cotton straw and wood chips was controlled at 20%, and adjusted The fitting linear relationship obtained by changing the different proportions of the two is almost a ^straight line, and the error analysis is within 2.0%. It is related to the quantity, but not related to the proportion relationship of each biomass blend.

Examples 12 and 13 of the present invention involve the co-combustion of different proportions of corn stalks and different coal samples (Guizhou coal, Inner Mongolia coal), and the obtained linear relationship has a goodness of fit R ² >0.99, which illustrates the real-time online monitoring system and analysis method It is suitable for co-combustion of single biomass and different coal samples. It can be seen from the above examples that the present invention is applicable to the co-combustion detection of various coals and various biomasses, and is less limited by the types of raw materials. Table 1 Coal and biomass physicochemical parameter table.

Claims (4)

1. A biomass blending combustion ratio on-line monitoring method based on stable carbon isotopes is characterized by comprising the following steps: (1) The flue gas taken from the boiler on-line for co-firing coal and biomass comprises ¹² CO ₂ 、 ¹³ CO ₂ Introducing the mixed gas into a carbon isotope mid-infrared laser detector for stable carbon isotope analysis, wherein the stable carbon isotope mid-infrared laser detector can directly test the carbon isotope ratio delta of the mixed flue gas ¹³ C( ¹³ C/ ¹² C) Delta of different coal samples and different Biomass ¹³ There was a significant difference between the C values; (2) According to said delta ¹³ And C, obtaining a linear regression equation after the carbon content of the coal and the biomass is corrected by using the difference, wherein the linear regression equation is used for calculating the co-combustion proportion of the biomass in the co-combustion substance:

in the formula (1), the first and second groups of the compound,ydelta shown for carbon isotope laser detection apparatus ¹³ The value of C is selected from the group consisting of,xis the biomass blending combustion ratio corrected by the carbon content, can eliminate the influence of interference factors of moisture, ash content and volatile matter after the carbon content correction,athe slope of a linear regression equation is obtained by proportioning different coal types and different biomass mixed combustion,bis delta of coal sample ¹³ C value; in the formula (2), the first and second groups of the compound,ris the biomass blending combustion ratio without carbon content correction,C _C the carbon content of the coal sample is shown as the content,C _B biomass carbon content; the biomass blending combustion ratio on-line monitoring system based on the stable carbon isotope comprises a flue gas on-line sampling channel, a condenser, a filter, a back pressure valve and a carbon isotope mid-infrared laser detector.

2. The method for on-line monitoring of stable carbon isotope-based biomass co-combustion ratio as claimed in claim 1, wherein the stable carbon isotope mid-infrared laser detection equipment can directly test the carbon isotope ratio δ of the mixed flue gas ¹³ C, and delta of different coal samples and different biomasses ¹³ The C value has obvious difference, and a linear regression equation can be obtained after the heat productivity of the coal and the biomass is corrected and is used for judging the blending combustion ratio of the biomass:

in the formula (3), the first and second groups,ydelta shown for carbon isotope laser detection apparatus ¹³ The value of C is selected from the group consisting of,x ₁ is the biomass blending combustion ratio after the calorific value is corrected,a ₁ the slope of a linear regression equation obtained by mixing and burning different coals and different biomasses is obtained,bis delta of coal sample ¹³ The C value can eliminate the influence of interference factors of moisture, ash and volatile after the heat productivity is corrected; in the formula (4), the first and second groups,r ₁ is the biomass blending combustion ratio without heat quantity correction,Q _C is the calorific value of the coal sample,Q _B is the biomass heating value.

3. The biomass co-combustion ratio on-line monitoring method based on the stable carbon isotope as claimed in claim 1, which is characterized in that: the error of the stable carbon isotope on-line detection equipment is only +/-0.025 thousandths, and the goodness of fit R of a linear regression equation ² >0.99, and the error range of the tested biomass fuel mixture ratio is controlled within 2.0 percent.

4. The biomass co-combustion ratio on-line monitoring method based on the stable carbon isotope as claimed in claim 1, which is characterized in that: the carbon isotope intermediate infrared laser detector mainly comprises a quantum cascade laser, a hollow waveguide tube and an intermediate infrared laser detector, wherein the hollow waveguide tube comprises a multi-channel light path, a laser inlet and a gas inlet/outlet;

the mixed flue gas enters a multi-channel light path in the hollow waveguide tube through the air inlet, the quantum cascade laser in the spectrum emits mid-infrared laser, the mid-infrared laser interacts with carbon dioxide gas molecules in the hollow waveguide tube through the hollow waveguide tube, and the infrared laser is irradiated by the carbon dioxide gas according to the Lambert beer lawThe absorption spectrum receives signals through a detector so as to measure the absorption value of the carbon isotope; the carbon isotope mid-infrared laser detector can measure a plurality of spectrum absorption peaks by measuring an absorption spectrum, wherein two main absorption peaks are the left side ¹³ CO ₂ Absorption peak and right side ¹² CO ₂ An absorption peak from which an isotope ratio delta contained in carbon dioxide gas is obtained ¹³ C, the isotope value can be given in real time; the infrared laser detector for carbon isotope is used for accurately measuring the content of carbon element and stable isotope value in various carbon-containing components ¹² C/ ¹³ C) Of simultaneous detection ¹² CO ₂ 、 ¹³ CO ₂ The stable carbon isotope value and the detection error of the carbon isotope mid-infrared laser detector are only +/-0.025 per thousand.

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