CN117314706A - Method for calculating carbon dioxide emission amount of coal-fired unit - Google Patents

Abstract

The invention discloses a method for calculating carbon dioxide emission of a coal-fired unit, which is used for obtaining corresponding measurement parameters and test data based on the existing measurement instrument and sampling test daily statement of the current thermal power plant and obtaining the daily, monthly and yearly carbon dioxide emission of the coal-fired unit according to the conservation law of carbon elements. According to the invention, the technical parameters which cannot be accurately obtained in the existing coal-fired unit are avoided, the influence of the unit state, the operation parameters and the coal quality change on the calculation of the carbon dioxide emission of the coal-fired unit every day is fully considered according to the field actual condition of the thermal power plant, and the carbon dioxide emission of the coal-fired unit is accurately obtained through the calculation of an empirical formula. The calculation result of the invention is closer to the true value, and can provide reliable basis for carbon emission transaction.

Description

A method for calculating carbon dioxide emissions from coal-fired units

Technical field

The invention relates to the technical field of carbon dioxide flow measurement in flue gas emissions from coal-fired units in thermal power plants, and more specifically to a method for calculating carbon dioxide emissions from coal-fired units.

Background technique

Carbon dioxide emissions from the power industry account for about 42% of the total carbon dioxide emissions from the energy industry. In the power industry, coal-fired units account for about 90% of carbon dioxide emissions. Coal-fired units are the main source of carbon dioxide emissions in the power industry. First, it is necessary to accurately measure the carbon dioxide emissions of coal-fired units, understand the carbon dioxide emission characteristics of coal-fired units, and then formulate corresponding emission reduction plans or incorporate them into the carbon emissions trading market for market-oriented operations.

At present, there are national greenhouse gas emission inventory guidelines given by the United Nations Intergovernmental Panel on Climate Change (IPCC). In 2015, my country issued the national standard GB/T 32151.1-2015 "Greenhouse Gas Emission Accounting Methods and Reporting Requirements Part 1: Power Generation Enterprises", relevant management departments have issued standards and guidelines such as the "Guidelines for Accounting Methods and Reporting of Greenhouse Gas Emissions by China's Power Generation Enterprises (Trial)", but the relevant methods in these guidelines and standards mainly consider the design and theory of a wide range of conceptual frameworks from the industry level In terms of calculation construction, the actual production situation of coal-fired units is not well understood, and there is a lack of research on the sampling analysis and operating parameter statistics of coal-fired units as well as the accuracy of the data. Therefore, some accounting methods are not fully applicable or the accounting results deviate greatly from the actual results.

Contents of the invention

In order to avoid the shortcomings of the above-mentioned existing technologies, the present invention provides a method for calculating carbon dioxide emissions of coal-fired units. Based on existing measuring instruments in thermal power plants, accurate measurement parameters of coal-fired units are obtained, and then the calculated coal-fired units are calculated. Accurate value of unit carbon dioxide emissions.

In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

The characteristics of the method for calculating the carbon dioxide emissions of the coal-fired unit of the present invention are: using the existing measuring instruments of the thermal power plant to measure and obtain the basic parameters of the coal-fired unit, and for the basic parameters, calculating and obtaining the carbon dioxide of the coal-fired unit according to the law of conservation of carbon elements. Emissions; the basic parameters include:

The low calorific value Q _{net,ar of} the coal fed into the furnace of the coal-fired unit every day; the high calorific value Q _{gr,ar of} the coal fed into the furnace of the coal-fired unit every day;

The total amount of water M _t of the coal fed into the furnace of the coal-fired unit every day; the basic ash content A _ar of the coal fed into the furnace of the coal-fired unit every day;

The sulfur element mass fraction S _ar of the coal fed into the furnace of the coal-fired unit every day; the carbon content of the fly ash of the coal-fired unit C _fh every day;

The daily carbon content of the slag of the coal-fired unit C _lz ; the mass fraction of fly ash in the total ash in the furnace coal a _fh ;

The mass fraction of slag in the total ash in the coal is a _lz ; the average daily coal consumption rate of coal-fired units for power generation B _fd ;

Coal-fired units generate electricity M every day;

The conversion rate k of SO ₂ in the flue gas generated by the reaction of sulfur element in the coal entering the coal-fired unit;

SO ₂ concentration in flue gas before desulfurization SO ₂ concentration in flue gas after desulfurization/>

The characteristic of the method for calculating carbon dioxide emissions from coal-fired units according to the present invention is that it proceeds as follows:

Step 1. Calculate according to formula (1) to obtain the carbon element mass fraction C _ar of the coal fed into the furnace of the coal-fired unit every day:

C _ar ＝0.2187M _t +0.006289Q _net,ar -0.003622Q _gr,ar (1)

Step 2. Calculate according to formula (2) to obtain the mass fraction C _wr of unburned carbon element in the coal fed into the furnace of the coal-fired unit every day:

Step 3. Calculate the carbon dioxide emissions E ₁ produced by the coal-fired unit burning coal into the furnace every day according to formula (3):

Step 4. Calculate the carbon dioxide emissions E ₂ produced during the daily desulfurization process of the coal-fired unit according to formula (4):

Step 5. Calculate the daily carbon dioxide emissions E _d of the coal-fired unit according to equation (5):

E _d =E ₁ +E ₂ (5)

This completes the calculation of daily carbon dioxide emissions from coal-fired units.

The characteristics of the carbon dioxide emission calculation method of coal-fired units of the present invention are also:

According to the daily carbon dioxide emissions E _d of coal-fired units, the monthly carbon dioxide emissions of coal-fired units are obtained through accumulation, and the annual carbon dioxide emissions of coal-fired units are obtained through accumulation.

The characteristics of the carbon dioxide emission calculation method of coal-fired units of the present invention are also:

The values of the basic parameters Q _net,ar , M _t , Q _gr,ar , S _ar and A _ar are obtained by sampling and testing the coal entering the furnace every day;

The value of the basic parameter C _fh is obtained by sampling and testing fly ash every day;

The value of the basic parameter C _lz is obtained by sampling and testing the slag every day;

The value of the basic parameter B _fd is obtained through statistics and calculation of the positive and negative balance method;

The value of the basic parameter M is obtained through electric energy measurement;

Basic parameters and/> The value is obtained through the thermal measuring points of the discrete control system of the coal-fired unit;

For pulverized coal boilers, the value of its basic parameter a _fh is taken as 90%, the value of its basic parameter a _lz is taken as 10%, and the value of its basic parameter k is taken as 0.9;

For the circulating fluidized bed boiler, the value of its basic parameter a _fh is taken as 60%, the value of its basic parameter a _lz is taken as 40%, and the value of its basic parameter k is taken as 0.9.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention uses the data of coal sampling and analysis of the coal entering the furnace every day from the power plant to calculate and obtain the carbon content of the coal entering the furnace every day through fitting empirical formulas, avoiding the need for the power plant to entrust a third-party testing agency to detect and analyze the carbon content of the coal entering the furnace for daily sampling. , reducing the cost of accounting for carbon dioxide emissions for power plants;

2. The present invention uses relatively accurate data such as coal consumption and power generation generated by the power plant every day to avoid data on flue gas flow and carbon dioxide concentration in the flue gas that cannot be accurately measured, thereby improving the accuracy of calculating carbon dioxide emissions from coal-fired units;

3. The present invention calculates the carbon dioxide emissions produced by desulfurization of the coal-fired unit from the change of sulfur dioxide concentration in the reactant flue gas according to the chemical equivalent method, and avoids the problem of inaccurate limestone flow measurement and limestone laboratory analysis.

4. The present invention fully considers the impact of daily unit status, operating parameters and coal quality changes on the calculation of carbon dioxide emissions from coal-fired units, and its calculation results are closer to the true value.

Detailed ways

In this embodiment, the method for calculating the carbon dioxide emissions of the coal-fired unit is to use the existing measuring instruments of the thermal power plant to measure and obtain the basic parameters of the coal-fired unit. For the basic parameters, the carbon dioxide emissions of the coal-fired unit are calculated according to the law of conservation of carbon elements; basically Parameters include:

The low calorific value Q _net,ar of the coal fed into the furnace of the coal-fired unit every day, the measurement unit is kJ/kg;

The high calorific value Q _gr,ar of the coal fed into the furnace of the coal-fired unit every day, the measurement unit is kJ/kg;

The total water M _t of the coal fed into the furnace of the coal-fired unit every day, measured as a percentage;

The base ash content A _ar received by coal-fired units into the furnace every day is calculated as a percentage;

The sulfur element mass fraction S _ar of the coal fed into the furnace of the coal-fired unit every day, measured in percentage;

The daily carbon content of fly ash from coal-fired units, C _fh , is measured in percentage;

The daily carbon content of the slag of the coal-fired unit C _lz , measured in percentage;

The mass fraction a _fh of fly ash in the total ash in the coal entering the furnace, expressed as a percentage;

The mass fraction a _lz of slag in the total ash in the coal entering the furnace, measured as a percentage;

The average daily coal consumption rate for power generation of coal-fired units is B _fd , and the measurement unit is g/kwh;

Coal-fired units generate electricity M per day, and the unit of measurement is Mwh;

The conversion rate k of SO ₂ in the flue gas generated by the reaction of sulfur element in the coal entering the coal-fired unit;

SO ₂ concentration in flue gas before desulfurization The measurement unit is mg/m ³ ;

SO ₂ concentration in flue gas after desulfurization The measurement unit is mg/m ³ .

In this embodiment, the calculation method of carbon dioxide emissions from coal-fired units is carried out as follows:

Step 1. Calculate according to formula (1) to obtain the carbon element mass fraction Car of the coal fed into the furnace of _the coal-fired unit every day, in percentage:

C _ar ＝0.2187M _t +0.006289Q _net,ar -0.003622Q _gr,ar (1)

Step 2. Calculate according to formula (2) to obtain the mass fraction C _wr of unburned carbon elements in the coal fed into the furnace of the coal-fired unit every day, in percentage:

Step 3. Calculate according to formula (3) to obtain the carbon dioxide emissions E ₁ produced by the coal-fired unit burning coal into the furnace every day, and the measurement unit is t/d;

Step 4. Calculate the carbon dioxide emissions E ₂ produced during the daily desulfurization process of the coal-fired unit according to formula (4). The measurement unit is t/d:

Step 5. Calculate the daily carbon dioxide emission E _d of the coal-fired unit according to formula (5), and the measurement unit is t/d:

E _d =E ₁ +E ₂ (5)

This completes the calculation of daily carbon dioxide emissions from coal-fired units.

In the specific implementation, based on the daily carbon dioxide emissions E _d of coal-fired units, the monthly carbon dioxide emissions of coal-fired units are obtained through accumulation, and the annual carbon dioxide emissions of coal-fired units are obtained through accumulation.

Among the basic parameters, the low calorific value Q _net,ar of the coal fed into the furnace of the coal-fired unit every day, the total water M _t of the coal fed into the furnace of the coal-fired unit every day, and the high calorific value Q _{gr,ar of} the coal fed into the furnace of the coal-fired unit every day The values of the sulfur element mass fraction S _ar of the coal fed into the furnace of the coal-fired unit every day and the basic ash content A _ar of the coal fed into the furnace of the coal-fired unit every day are obtained by sampling and testing the coal fed into the furnace every day.

The value of the carbon content C _fh of the daily fly ash of the coal-fired unit is obtained by sampling and testing the fly ash every day;

The value of the daily carbon content C _lz of the slag of the coal-fired unit is obtained by sampling and testing the slag every day;

The value of the average daily power generation coal consumption rate B _fd of coal-fired units is obtained through statistics and calculations of the forward and reverse balance methods;

The value of the daily power generation M of the coal-fired unit is obtained through electric energy measurement;

SO ₂ concentration in flue gas before desulfurization and SO ₂ concentration in the flue gas after desulfurization/> The value is obtained through the thermal measuring points of the discrete control system of the coal-fired unit;

For pulverized coal boilers, the mass fraction a _fh of fly ash in the total ash in the coal entering the furnace is taken to be 90%, and the mass fraction a _lz of the slag in the total ash in the coal entering the furnace is taken to be 10%. The conversion rate k of the sulfur element in the coal entering the furnace of the coal unit to generate SO ₂ in the flue gas is 0.9;

For circulating fluidized bed boilers, the mass fraction a _fh of fly ash in the total ash in the coal entering the furnace is taken to be 60%, and the mass fraction a _lz of the slag in the total ash in the coal entering the furnace is taken to be 40%. The value k of the conversion rate k of SO ₂ in the flue gas generated by the reaction of sulfur in the coal entering the coal-fired unit is 0.9.

Applications:

The carbon dioxide emissions of a certain coal-fired unit in a power plant on a certain day are calculated as follows:

The first step is to obtain the laboratory analysis data of coal quality, fly ash and slag carbon content of a certain unit on a certain day from the daily report of furnace coal, fly ash and slag data, as shown in Table 1.

Table 1

Related parameters unit numerical value Q _net,ar kJ/kg 18280 Q _gr,ar kJ/kg 19101 M _t % 5.16 A % 35.56 S % 0.56 _f % 0.97 _zz % 1.00

In the second step, the operating parameters of a certain unit on a certain day are obtained from the daily production indicator report, as shown in Table 2.

Table 2

The third step is to calculate the above data according to the corresponding formulas from steps 1 to 5 to calculate the carbon dioxide emissions of a certain unit on a certain day. The calculation results are shown in Table 3.

table 3

Calculation results unit numerical value C % 46.91 C % 0.35 E ₁ t/d 6227.635 E ₂ t/d 24.988 E _d t/d 6252.623

The data in Table 1 are obtained from the daily laboratory report of the coal and ash entering the furnace of the thermal power plant. The low calorific value Q _net,ar , high calorific value Q _gr,ar , total water M _t , ash content A _ar , The sulfur content _Sar , the carbon content of fly ash C _fh , and the carbon content of slag C _lz ; from the daily report of thermal power plant production indicators, the data in Table 2 are obtained, the power generation capacity M of the unit, and the coal consumption rate B _fd , the concentration of SO ₂ in the flue gas before desulfurization Concentration of SO ₂ in flue gas after desulfurization/> Calculate the mass fraction of carbon element C _ar in the coal entering the furnace according to the fitted empirical formula; calculate the mass fraction C _wr of unburned carbon element in the coal entering the furnace through the relevant formula; finally calculate the carbon dioxide generated by the combustion of coal entering the furnace in the coal-fired unit The sum of the amount E ₁ and the amount of carbon dioxide generated by desulfurization E ₂ is equal to the carbon dioxide emissions E _d of the coal-fired unit that day. The calculation method disclosed in the present invention can simply and accurately calculate the carbon dioxide emissions of coal-fired units based on the existing data of thermal power plants.

The key to the accuracy of the calculation method disclosed in the present invention lies in the accuracy of the fitting empirical formula for calculating the carbon mass fraction of the coal entering the furnace. The fitting empirical formula uses 139 sets of laboratory test data on the coal quality of coal-fired units in a certain area in the past two years to perform multiple linear regression. The residual error is within the range of ±1.6%, that is, the carbon dioxide emission error is calculated using the calculation method of the present invention. Within ±1.6%.

Research shows that when thermal power plants take coal samples and entrust a coal quality testing agency to directly analyze the carbon element mass fraction of coal entering the furnace, the uncertainty is about ±1.25%; while directly measuring the concentration of CO ₂ and flue gas flow in the flue gas The measurement error of the _CO2 emission online monitoring system is around ±10%. The calculation method disclosed in the present invention can relatively accurately and timely calculate the carbon dioxide emissions of coal-fired units without increasing the additional cost of the power plant.

Claims (4)

1. A method for calculating the carbon dioxide emission amount of a coal-fired unit is characterized by comprising the following steps: measuring and obtaining basic parameters of the coal-fired unit by using the existing measuring instrument of the thermal power plant, and calculating and obtaining the carbon dioxide emission of the coal-fired unit according to the conservation law of carbon aiming at the basic parameters; the basic parameters include:

low-position heat value Q of coal fired unit for daily feeding of coal _net,ar ；

High-position heat value Q of coal fired unit daily feeding coal _gr,ar ；

Whole water M for coal fired unit to feed coal every day _t ；

Received base ash content A of coal fired unit coal fed into furnace every day _ar ；

Sulfur element mass fraction S of coal fired unit daily _ar ；

Carbon content C of fly ash of coal-fired unit every day _fh ；

Carbon content C of furnace slag of coal-fired unit every day _lz ；

The fly ash accounts for the mass fraction a of the total ash in the coal charged into the furnace _fh ；

Mass fraction a of slag to total ash in coal charged into furnace _lz ；

Average daily power generation coal consumption rate B of coal-fired unit _fd ；

Generating energy M of the coal-fired unit every day;

sulfur element in coal fired unit furnace coal reacts to generate SO in flue gas ₂ Conversion k of (2);

SO in flue gas in flue before desulfurization ₂ Concentration of

SO in flue gas in flue after desulfurization ₂ Concentration of

2. The method for calculating the carbon dioxide emission amount of the coal-fired unit according to claim 1, characterized by comprising the steps of:

step 1, calculating according to the formula (1) to obtain the mass fraction C of carbon elements of coal fired in the coal-fired unit every day _ar ：

C _ar ＝0.2187M _t +0.006289Q _net,ar -0.003622Q _gr,ar (1)

Step 2, calculating according to the step 2 to obtain the mass fraction C of unburned carbon element in coal fed into the furnace every day of the coal-fired unit _wr ：

Step 3, calculating according to the step 3 to obtain the carbon dioxide emission E generated by burning coal into the furnace every day of the coal-fired unit ₁ ：

Step 4, calculating and obtaining carbon dioxide emission E generated in the daily desulfurization process of the coal-fired unit according to the step 4 ₂ ：

Step 5, calculating according to the step 5 to obtain the daily carbon dioxide emission E of the coal-fired unit _d ：

E _d ＝E ₁ +E ₂ (5)

Thus, the daily carbon dioxide emission of the coal-fired unit is calculated.

3. The method for calculating the carbon dioxide emission amount of the coal-fired unit according to claim 2, characterized in that:

according to the daily carbon dioxide emission E of the coal-fired unit _d The monthly carbon dioxide emission of the coal-fired unit is obtained through accumulation, and the annual carbon dioxide emission of the coal-fired unit is obtained through accumulation.

4. The method for calculating the carbon dioxide emission amount of the coal-fired unit according to claim 1 or 2, characterized in that:

basic parameter Q _net,ar 、M _t 、Q _gr,ar 、S _ar And A _ar The value of (2) is obtained by sampling and testing the coal fed into the furnace every day;

basic parameter C _fh The value of (2) is obtained by sampling and assaying fly ash every day;

basic parameter C _lz The value of (2) is obtained by sampling and assaying the slag every dayObtaining the product;

basic parameters B _fd The value of (2) is obtained by statistics and calculation through a positive and negative balance method;

the value of the basic parameter M is obtained through electric energy metering;

basic parametersAnd->The value of (2) is obtained through a thermal measuring point of a discrete control system of the coal-fired unit;

for pulverized coal boiler, basic parameter a thereof _fh Takes the value of 90%, the basic parameter a _lz The value of (2) is 10%, and the value of the basic parameter k is 0.9;

for a circulating fluidized bed boiler, the basic parameter a thereof _fh The value of (a) is taken to be 60%, and the basic parameter a is _lz The value of (2) is 40% and the value of the basic parameter k is 0.9.