A method for accurately determining the combustion ratio of biomass to coal in coupled combustion

Abstract

This invention discloses a method for accurately determining the ratio of biomass to coal combustion in coupled combustion. The method includes the following steps: first, simultaneously collecting boiler flue gas samples and combustion-supporting atmospheric samples; purifying the flue gas and atmospheric samples to obtain CO2 gas; and then experimentally determining the content of CO2 gas... 14 C and 13 The level of C is obtained by consulting database data or through experiments to obtain biomass fuel. 14 C and 13 The endmember values ​​of C are calculated using a Bayesian mixture model to accurately distinguish the contribution ratios of different carbon-containing components in biomass, coal, and the atmosphere. The method provided by this invention, compared to traditional methods... 14 C analysis method, using 13 The contribution of atmospheric CO2 to flue gas was quantified to optimize gas sample collection methods and establish a model for different types of biomass samples. 14 C and 13 The C database greatly improves the accuracy of biomass co-combustion ratio analysis and provides technical support for carbon emission reduction assessment methods for power plants in my country.

Description

Technical Field

[0001] This invention belongs to the field of biomass co-firing power generation technology, specifically relating to a method for determining the ratio of biomass to coal combustion in co-firing. Background Technology

[0002] High-precision monitoring technology for biomass coupling ratios is a crucial guarantee for the rational and orderly development of biomass power plants. Radiocarbon isotopes. 14 C has a half-life of 5730 years, which is significant during the long formation process of fossil fuels. 14 Carbon has almost completely decayed, while the carbon fixed by biomass through photosynthesis is close to the current atmospheric level. 14 C content, therefore radioactive carbon ( 14 C) Tracer methods can accurately distinguish the contributions of coal and biomass and are less affected by human factors, thus possessing objectivity. Currently, there are relevant research reports in this field abroad, and there is a consensus that... 14 C-technology has significant advantages in terms of detection accuracy and reliability. Although my country's biomass power generation started relatively late, with the support of relevant policies, several biomass gasification coupled with pulverized coal boiler projects are already in operation or planned. 14 The C-detection method has good application demand and development prospects. However, since biomass fuel in my country is mainly derived from agricultural waste, its utilization... 14 Accurately quantifying the proportion of biomass co-combustion in my country's coal-fired power units still faces some challenges, and there is a lack of suitable methods for biomass power plants in my country. 14 C-detection technology and methodology system.

[0003] In the existing 14 In the C model, atmospheric carbon is often ignored or estimated, increasing the uncertainty in detecting biomass co-combustion ratios. Stable carbon isotopes from atmospheric CO2 in power plant flue gas. 13 C with coal and biomass 13 There are significant differences in carbon content (C). When different fuels are completely burned in a power plant boiler with the atmosphere, according to the principle of carbon isotope conservation, the CO2 in the produced flue gas will differ. 14 C and 13 C is the weighted value of carbon isotopes in different fuel components (coal, biomass, and atmosphere). 14 Based on C, combined with 13 The C-carbon dual-carbon isotope mixing model can correct for interference from atmospheric carbon, further improving the accuracy of biomass co-combustion ratio analysis. Summary of the Invention

[0004] The purpose of this invention is to provide a method for accurately determining the ratio of biomass to coal combustion in coupled combustion.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for determining the ratio of biomass to coal combustion in coupled combustion, characterized in that the method comprises the following steps:

[0007] The flue gas collection system simultaneously collects flue gas samples emitted from the boiler under stable combustion and atmospheric samples entering the combustion environment. The collected flue gas and atmospheric samples are then slowly released into a vacuum purification system. The samples are purified using a cryogenic liquid nitrogen cold trap (-196℃) and a liquid nitrogen + alcohol cold trap (-90℃) before CO2 gas is collected.

[0008] Biomass and coal samples were collected and rinsed with distilled water. They were dried at 60-70℃ for 48 hours and ground into powder. Appropriate amounts of the samples were weighed into different quartz tubes, and CuO powder was added. After vacuuming, the samples were reacted at 800℃ to generate CO2, which was then purified by liquid nitrogen freezing.

[0009] A portion of the CO2 sample was sent to a stable carbon isotope laboratory for stable carbon isotope analysis using a MAT253 plus mass spectrometer, yielding the results of stable carbon isotope analysis in the sample. 13 The level of C is

[0010] in( 13 C / 12 C) OX For the sample, ( 13 C / 12 C) PDB As the standard.

[0011] Another portion of the CO2 sample was reduced to graphite using the Zn-Fe or H2-Fe method, then pressed onto a target and sent to the laboratory for further processing. 14 C was determined, and the obtained δ was analyzed using AMS. 13 C performs Δ 14 Fractional correction of C yields the sample. 14 The level of C is:

[0012]

[0013] in( 14 C / 12 C) SN After isotopic mass fractionation correction 14 The radioactivity ratio of C, ( 14 C / 12 C) abs For the absolute international (modern carbon) standard of 1950, corrected for isotopic mass fractionation and decay. 14 The radioactivity ratio of C.

[0014] Considering the spatiotemporal differences in carbon isotope composition in the environment, it is necessary to obtain the Δt of common biomass fuels in different regions of my country through literature or field measurements. 14 C and δ 13 Spatiotemporal distribution data of C were used to establish various types of biomass. 14 C and 13 The C-end value database leverages the regional and stable characteristics of biomass fuel transportation and consumption in my country to provide parameters for biomass co-firing power plants.

[0015] By analyzing the experimental data 14 C-analysis distinguishes the combustion ratio of biomass and coal, and combines it with 13 C-analysis quantifies the contribution of atmospheric CO2 to flue gas, and a Bayesian mixture model is used to calculate the blending ratio of biomass and coal co-combustion using multiple sources, resulting in an accurate and high-precision result.

[0016] Dual-carbon desorption mass balance model:

[0017] Δ 14 C 生物 *f 生物 +Δ 14 C 煤 *f 煤 +Δ 14 C 大气 *f 大气 =Δ 14 C 烟气

[0018] δ 13 C 生物 *f 生物 +δ 13 C 煤 *f 煤 +δ 13 C 大气 f 大气 =δ 13 C 烟气

[0019] f 生物 +f 煤 +f 大气 =1

[0020] Δ 14 C 生物 Δ 14 C 煤 Δ 14 C 大气 Δ 14 C 烟气 These are biomass fuel, coal, air, and flue gas. 14 C concentration;

[0021] δ13 C 生物 δ 13 C 煤 δ 13 C 大气 δ 13 C 烟气 These are biomass fuel, coal, air, and flue gas. 13 C concentration;

[0022] f 生物 f 煤 f 大气 This represents the proportion of different sources in the flue gas.

[0023] Compared with traditional 14 C-analysis quantified atmospheric concentrations. 13 The addition of carbon content further improves the accuracy of the results, providing technical support for my country's power plant carbon emission reduction assessment methods. Attached Figure Description

[0024] Figure 1 This is a flowchart of the invention method;

[0025] Figure 2 This is a schematic diagram of the flue gas collection system. Detailed Implementation

[0026] The following examples illustrate specific implementations of the present invention. However, these examples are merely for illustrative purposes and do not limit the scope of the invention in any way.

[0027] A method for determining the ratio of biomass to coal combustion in coupled combustion, comprising the following steps:

[0028] (1) Insert the sampling probe into the flue after the preheater, first turn on the flue gas analyzer path, monitor the changes in the concentration of gases such as CO2, CO, and O2 in the flue gas. If the concentration fluctuation is small, confirm that the combustion boiler is in a stable operating state, then turn on the flue gas collection path to start collecting flue gas and the atmosphere blown into the boiler.

[0029] (2) Evacuate the 5L aluminum foil composite film gas bag to 0.1mbar, install it on the flue gas collection device, open the flue gas collection channel, set the sampling flow rate to 200ml / min, and the sampling time to 25min. After collection, immediately send it to the laboratory for CO2 (including...) determination. 12 CO2 and 13 Concentrations of gases such as CO2 and CO.

[0030] (3) Install the alkali absorption bottle containing 3 mol / L NaOH in 100 ml onto the flue gas collection device, turn on the flue gas collection path, the sampling flow rate is 200 ml / min, the single sampling time is 1 h, the flow rate is adjusted by the speed regulating pump, the instantaneous flow rate and sampling volume are recorded by the electronic flow meter, collect 5 times continuously, with an interval of 30 min between each time, and after the collection is completed, transfer it to the laboratory for refrigeration.

[0031] (4) The collected flue gas is slowly released into the vacuum purification system. The CO2 gas is collected after the sample is purified by the low temperature liquid nitrogen cold trap (-196℃) and liquid nitrogen + alcohol cold trap (-90℃).

[0032] (5) Collect biomass samples and rinse them with distilled water. Dry them at 60-70℃ for 48 hours, grind them into powder, weigh an appropriate amount of sample into a quartz tube, add CuO powder, and react at 800℃ under vacuum to generate CO2. Then purify the sample by freezing with liquid nitrogen.

[0033] (6) A portion of the CO2 sample was sent to a stable carbon isotope laboratory for stable carbon isotope analysis using a MAT253 Plus mass spectrometer. The sample contained... 13 The level of C is

[0034] in( 13 C / 12 C) ox For the sample, ( 13 C / 12 C) PDB As the standard.

[0035] Another portion of the CO2 sample was reduced to graphite using the Zn-Fe or H2-Fe method, then pressed onto a target and sent to the laboratory for further processing. 14 C was determined, and δ was obtained using AMS. 13 C performs Δ 14 Fractional correction for C. In the sample 14 The level of C is usually expressed by Δ 14 C represents, and is defined as:

[0036]

[0037] in( 14 C / 12 C) SN After isotopic mass fractionation correction 14 The radioactivity ratio of C, ( 14 C / 12 C) abs For the absolute international (modern carbon) standard of 1950, corrected for isotopic mass fractionation and decay.14 The radioactivity ratio of C (Stuiver and Polach, 1977).

[0038] (7) Obtain the Δ values ​​of common biomass fuels in agriculture, forestry, animal husbandry, etc. in different regions of my country through literature or field measurements. 14 C and δ 13 The spatiotemporal distribution data of C was used to establish a database, which was then applied to the co-firing of biomass fuels primarily used in agriculture, forestry, and animal husbandry. This was achieved by analyzing the actual fuel composition... 14 C and 13 C data acquisition endpoint values ​​are applied to situations involving the co-incineration of municipal solid waste, industrial waste, and domestic sludge.

[0039] (8) By analyzing the experimental data 14 C-analysis distinguishes the combustion ratio of biomass and coal, and combines it with 13 C-analysis quantifies the contribution of atmospheric CO2 to flue gas, and a Bayesian mixture model is used to calculate the blending ratio of biomass and coal co-combustion using multiple sources, resulting in an accurate and high-precision result.

[0040] Dual-carbon desorption mass balance model:

[0041] Δ 14 C 生物 *f 生物 +Δ 14 C 煤 *f 煤 +Δ 14 C 大气 *f 大气 =Δ 14 C 烟气

[0042] δ 13 C 生物 *f 生物 +δ 13 C 煤 *f 煤 +δ 13 C 大气 f 大气 =δ 13 C 烟气

[0043] f 生物 +f 煤 +f 大气 =1

[0044] Δ 14 C 生物 Δ 14 C 煤 Δ 14 C 大气 Δ 14 C烟气 These are biomass fuel, coal, air, and flue gas. 14 C concentration;

[0045] δ 13 C 生物 δ 13 C 煤 δ 13 C 大气 δ 13 C 烟气 These are biomass fuel, coal, air, and flue gas. 13 C concentration;

[0046] This method can accurately determine the ratio of biomass to coal in coupled combustion, providing technical support for my country's power plant carbon emission reduction assessment methods.

Claims

1. A method for accurately determining the ratio of biomass to coal combustion in coupled combustion, characterized in that, The method includes the following steps: (1) Use a flue gas collection system to collect the flue gas emitted by the boiler under stable combustion, slowly release the collected flue gas into a vacuum purification system for purification, and collect CO2 gas; (2) At the same time, atmospheric samples are collected from the boiler, and the collected atmospheric samples are slowly released into the vacuum purification system for purification, and CO2 gas is collected. (3) Collect biomass and coal samples and wash them with distilled water. After drying, grind them into powder, react to generate CO2, and then purify them by freezing with liquid nitrogen. (4) A portion of the CO2 sample was analyzed for stable carbon isotopes using a MAT253 plus mass spectrometer to obtain the δ¹⁸O values ​​in the sample. 13 The level of C is: in( 13 C / 12 C) OX For the sample, ( 13 C / 12 C) PDB As a standard; (5) Another portion of the CO2 sample was analyzed and sent to the laboratory for further processing. 14 C was determined, and the obtained δ was analyzed using AMS. 13 C performs Δ 14 Fractional correction of C yields the sample. 14 The level of C is: in( 14 C / 12 C) SN After isotopic mass fractionation correction 14 The radioactivity ratio of C, ( 14 C / 12 C) abs For the absolute international standard of 1950, after isotopic mass fractionation correction and decay correction. 14 The radioactivity ratio of C; (6) Obtain the Δ values ​​of common biomass fuels in agriculture, forestry, and animal husbandry in different regions of my country through literature review or field measurements. 14 C and δ 13 Spatiotemporal distribution data of C were used to establish various types of biomass. 14 C and 13 The C-end meta-value database is applied to situations where biomass fuels are mainly used in agriculture, forestry and animal husbandry, replacing the actual measurement and analysis under each fuel change during the production process. (7) By analyzing the experimental data 14 C-analysis distinguishes the combustion ratio of biomass and coal, and combines it with 13 C-analysis quantifies the contribution of atmospheric CO2 to flue gas. A Bayesian mixture model is used to calculate the blending ratio of biomass and coal in the co-combustion process, yielding the following: D 14 C 生物 *f 生物 +D 14 C 煤 *f 煤 +D 14 C 大气 *f 大气 =D 14 C 烟气 d 13 C 生物 *f 生物 +d 13 C 煤 *f 煤 +d 13 C 大气 f 大气 =d 13 C 烟气 f 生物 +f 煤 +f 大气 =1 Δ 14 C 生物 Δ 14 C 煤 Δ 14 C 大气 Δ 14 C 烟气 These are biomass fuel, coal, air, and flue gas. 14 C concentration; δ 13 C 生物 δ 13 C 煤 δ 13 C 大气 δ 13 C 烟气 These are biomass fuel, coal, air, and flue gas. 13 C concentration; f 生物 f 煤 f 大气 This represents the proportion of different sources in the flue gas.

2. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: The flue gas collection system includes a flue gas cooling device, a flue gas purification device, a flow controller, a vacuum pump, a flue gas CO2 capture device, and a flue gas analyzer.

3. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: In step (1), during the sample purification stage, CO2 gas is collected after the sample is purified using a low-temperature liquid nitrogen cold trap and a liquid nitrogen + alcohol cold trap.

4. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: In step (3), during the biomass sample drying stage, the drying temperature is 50-80℃ and the drying time is 45-50 hours.

5. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: In step (3), during the sample conversion stage, after the sample is evacuated, it reacts with CuO powder under high temperature conditions to generate CO2.

6. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: In step (5), during the sample analysis stage, the CO2 sample is reduced to graphite using the Zn-Fe method or the H2-Fe method. 14 C was determined to obtain the sample content. 14 Level C.

7. The method for accurately determining the ratio of biomass to coal combustion in coupled combustion according to claim 1, characterized in that: In step (6), when agricultural, forestry, and livestock products are used as biomass fuel, data is directly queried from the database. When municipal solid waste, industrial and domestic sludge are mixed and burned, the data is analyzed based on the actual fuel composition. 14 C and 13 C data acquisition endpoint values.

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