System and method for measuring the amount of nitrogen oxides released by cement raw materials in a preheater

Abstract

The present application belongs to the field of flue gas denitration in cement industry, and particularly relates to a system and method for measuring the amount of nitrogen oxides released by cement raw materials in a preheater, which comprises the following steps: I. taking the raw materials of a cement clinker production line and weighing; II. installing a measuring system; III. recording the curve of the relationship between the nitrogen oxide concentration data of a flue gas analyzer and time; IV. calculating the amount of nitrogen oxides released by unit mass of raw materials according to the curve of the relationship between the nitrogen oxide concentration data of the flue gas analyzer and time, the flue gas flow of the flue gas analyzer and the mass of the raw materials; and V. obtaining the amount of increase in the emission concentration of nitrogen oxides caused by nitrogen in the raw materials by dividing the amount of nitrogen oxides released by unit mass of raw materials by the standard state flue gas amount corresponding to unit mass of the raw materials. The present application provides a basis for enterprises to design the emission concentration of nitrogen oxides in advance and avoid exceeding the standard.

Description

Technical Field

[0001] This invention belongs to the field of flue gas denitrification in the cement industry, specifically relating to a system and method for measuring the amount of nitrogen oxides released by cement raw materials in a preheater. Background Technology

[0002] Nitrogen oxides are harmful pollutants that can easily cause acid rain and other damage. To strengthen environmental protection, it is necessary to strictly control nitrogen oxide emissions.

[0003] Generally, based on the generation mechanism of nitrogen oxides (NOx) in cement calcination systems, NOx is mainly classified into three types: thermodynamic NOx, fuel-based NOx, and rapid NOx. The generation ratio among these three types depends on the nitrogen content in the raw materials and fuels, the combustion temperature, and the type of fuel. Most experts believe that the main sources of NOx in dry-process cement kiln production systems are the rotary kiln and the precalciner, and the nitrogen content in the raw materials has a negligible impact on the total NOx generation during cement production.

[0004] In practice, it has been found that in actual cement plant flue gas emissions, nitrogen from raw materials releases nitrogen oxides (NOx) in the preheater. These raw material NOx emissions have a significant impact on the total NOx production during cement production, increasing NOx emission concentrations by 30-200 mg / m³. 3 In some cases, the concentration can reach 400 mg / m². 3 Especially with the widespread implementation of ultra-low emissions in my country, the nitrogen oxide emission standard has been raised from the original emission concentration of 320 mg / m³. 3 Reduced to 100 mg / m 3 The amount of nitrogen oxides released from nitrogen in the raw materials during the preheater is even more significant. Currently, many cement plants use technologies such as SNCR (Synthetic Non-Cyclic Reduction) and low-NOx combustion to control NOx emissions. A common characteristic of these technologies is that they control NOx emissions in the decomposition furnace, but cannot control NOx released in the preheater. Therefore, when nitrogen in the raw materials releases NOx during the preheating period, they are often at a loss and unable to cope. Furthermore, environmental protection companies, when designing denitrification systems, may fail to analyze nitrogen oxides in the raw materials, leading to SNCR and low-NOx combustion systems failing to meet emission requirements, and the denitrification effect of the SCR system being affected. However, currently, there is no method to measure the amount of NOx released from the raw materials in the preheater and the resulting increase in NOx emission concentration. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems in the prior art, the purpose of this invention is to provide a system and method for measuring the amount of nitrogen oxides released by cement raw materials in the preheater, providing a basis for enterprises to design nitrogen oxide emission concentrations in advance and avoid exceeding the standards.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A system for measuring the amount of nitrogen oxides released by cement raw materials in a preheater includes a heating furnace; a reaction tube is connected to the inlet and outlet of the heating furnace via flanges, wherein the reaction tube at the inlet of the heating furnace is in communication with the atmosphere, and the other reaction tube is connected to a flue gas analyzer after natural cooling via a hose; an open container is placed inside the heating furnace for holding the raw materials; in addition, a temperature sensing element is provided inside the heating furnace and connected to a temperature controller outside the furnace.

[0008] This invention also discloses a method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the above-mentioned measuring system, comprising the following steps:

[0009] Step 1: Take the raw materials from the cement clinker production line and weigh them;

[0010] Step 2: Load the raw materials into the reaction tubes and install the reaction tubes. One reaction tube is connected to the atmosphere, and the other is connected to the flue gas analyzer after being cooled naturally through a hose.

[0011] Step 3: Record the relationship curve between the nitrogen oxide concentration data of the flue gas analyzer and time;

[0012] Step 4: Calculate the amount of nitrogen oxides released per unit mass of raw material by using the relationship curve between nitrogen oxide concentration data and time from the flue gas analyzer, the flue gas flow rate from the flue gas analyzer, and the mass of the raw material.

[0013] Step 5: Divide the amount of nitrogen oxides released per unit mass of raw material by the standard state flue gas volume corresponding to that unit mass of raw material to obtain the increase in nitrogen oxide emission concentration caused by nitrogen in the raw material.

[0014] As a preferred technical solution, in step one, if a single component of the cement raw meal is used, the component must be crushed and ground to the same fineness as the cement raw meal powder entering the kiln.

[0015] As a preferred technical solution, in step two, the reaction temperature of the reaction tube is 600-770℃.

[0016] As a preferred technical solution, in step three, the values ​​of NO and NO2 measured by the flue gas analyzer per minute are summed to obtain ΣNOx, and recorded until ΣNOx reaches a constant value, namely ΣNOxmax, while simultaneously recording the time T (in minutes).

[0017] As a preferred technical solution, in step four, the process of obtaining the amount of nitrogen oxides released per unit mass of raw material is as follows:

[0018] 1) Calculate the average NOx concentration of the flue gas entering the flue gas analyzer. mean NOx mean =ΣNOxmax / T;

[0019] 2) Calculate the total NOx release volume from the raw materials. volume NOx volume =NOx mean *T*V flue gas analyzer / 1000000; where V flue gas analyzer The flow rate of the flue gas analyzer;

[0020] 3) Calculate the total amount of NOx released from the raw materials. mol NOx mol =NOx volume / 22.4;

[0021] 4) Calculate the total NOx release from the raw materials by mass. quality NOx quality =NOx mol *46;

[0022] 5) Calculate the amount of nitrogen oxides (NOx) released per unit mass of raw material. raw NOx raw =NOx quality / m*10^9; where m is the mass of the raw material.

[0023] As a preferred technical solution, in step five, the increase in nitrogen oxide emission concentration caused by nitrogen in the raw materials, ΔNOx = NOx raw / V flue gas *X, V flue gas X represents the standard state flue gas volume corresponding to one ton of clinker, and X is the mass ratio of the raw material to the clinker.

[0024] As a preferred technical solution, the predicted nitrogen oxide emission concentration of cement plants without SCR denitrification technology = the minimum nitrogen oxide emission concentration after SNCR + the increase in nitrogen oxide emission concentration caused by nitrogen in raw materials;

[0025] The nitrogen oxide emission concentration of a cement plant using SCR denitrification technology = (nitrogen oxide emission concentration after SNCR + increase in nitrogen oxide emission concentration caused by nitrogen in raw materials) * (1 - denitrification efficiency of SCR method).

[0026] The advantages and positive effects of this invention are:

[0027] 1. By analyzing the raw materials, the increase in nitrogen oxide emission concentration caused by nitrogen in the raw materials can be determined;

[0028] 2. It can determine the nitrogen oxide emission concentration after a cement production line adopts staged combustion technology and SNCR technology;

[0029] 3. It can determine whether cement production lines using staged combustion technology, SNCR technology, SCR technology, or other denitrification technologies can meet ultra-low emission requirements;

[0030] 4. When cement companies cannot meet ultra-low emission requirements by using staged combustion technology or SNCR technology, it can help cement companies select suitable raw materials. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the measurement system of the present invention.

[0032] 1. Reaction tube, 2. Heating furnace, 3. Open container, 4. Temperature controller, 7. Temperature sensing element, 6. Hoses, 7. Flue gas analyzer, 8. Raw materials. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below; obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, the present invention discloses a system for measuring the amount of nitrogen oxides released by cement raw materials in a preheater, including a reaction tube 1, a horizontal heating furnace 2, an open container 3, a temperature controller 4, a temperature sensing element 7, a hose 6, and a flue gas analyzer 7.

[0035] The furnace 2 has a reaction tube 1 connected to its inlet and outlet via flanges. The reaction tube at the inlet of the furnace 2 is open to the atmosphere, and the other reaction tube is connected to the flue gas analyzer after being cooled naturally by a hose. An open container 3, such as a crucible, is placed inside the furnace to hold the raw materials 8. In addition, the furnace 2 is equipped with a temperature sensing element 7, such as a thermocouple, which is connected to a temperature controller 4 outside the furnace.

[0036] The present invention also discloses a method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the above-described system, comprising the following steps:

[0037] Step 1: Take the raw materials from the cement clinker production line and weigh them;

[0038] Step 2: Load the raw materials into the reaction tubes and install the reaction tubes. One reaction tube is connected to the atmosphere, and the other is connected to the flue gas analyzer after being cooled naturally through a hose.

[0039] Step 3: Record the relationship curve between the nitrogen oxide concentration data of the flue gas analyzer and time;

[0040] Step 4: Calculate the amount of nitrogen oxides released per unit mass of raw material by using the relationship curve between nitrogen oxide concentration data and time from the flue gas analyzer, the flue gas flow rate from the flue gas analyzer, and the mass of the raw material.

[0041] Step 5: Divide the amount of nitrogen oxides released per unit mass of raw material by the standard state flue gas volume corresponding to that unit mass of raw material to obtain the increase in nitrogen oxide emission concentration caused by nitrogen in the raw material.

[0042] Furthermore, in step one, if a single component of the cement raw meal is used, such as limestone, iron ore, sandstone, shale, etc., the component must be crushed and ground to the same fineness as the cement raw meal powder entering the kiln.

[0043] Furthermore, in step one, if the raw meal powder used is for kiln use, it can be directly sampled from the raw meal storage.

[0044] Furthermore, in step two, the reaction tube is a horizontally placed tubular reactor made of stainless steel or quartz, and the reaction temperature is 600-770℃.

[0045] Furthermore, in step three, the values ​​of NO and NO2 per minute (in ppm) measured by the flue gas analyzer are summed to obtain ΣNOx (in ppm), and recorded until ΣNOx reaches a constant value, namely ΣNOxmax, while simultaneously recording the time T (in min).

[0046] Furthermore, in step four, the process of obtaining the amount of nitrogen oxides released per unit mass of raw material is as follows:

[0047] 1) Calculate the average NOx concentration of the flue gas entering the flue gas analyzer. mean NOx mean =ΣNOxmax / T;

[0048] 2) Calculate the total NOx release volume from the raw materials. volume (unit: L), NOx volume =NOx mean *T*V flue gas analyzer / 1000000; where V flue gas analyzerFlue gas analyzer flow rate, unit: L / min;

[0049] 3) Calculate the total amount of NOx released from the raw materials. mol (unit: mol), NOx mol =NOx volume / 22.4;

[0050] 4) Calculate the total NOx release from the raw materials by mass. quality (unit: g), NOx quality =NOx mol *46;

[0051] 5) Calculate the amount of nitrogen oxides (NOx) released per unit mass of raw material. raw (unit: mg / t), NOx raw =NOx quality / m*10^9; where m is the mass of the raw material, in g;

[0052] Furthermore, in step five, the increase in nitrogen oxide emission concentration caused by nitrogen in the raw materials, ΔNOx = NOx raw / V flue gas *X (ratio of raw material to clinker by mass), V flue gas The standard state flue gas volume corresponding to one ton of clinker, in m³. 3 / t.cl).

[0053] The present invention provides a method and system for determining the amount of nitrogen oxides released by cement raw materials in a preheater. The predicted nitrogen oxide emission concentration of a cement plant without using SCR denitrification technology is: minimum nitrogen oxide emission concentration after SNCR + increase in nitrogen oxide emission concentration caused by nitrogen in the raw meal.

[0054] The nitrogen oxide emission concentration of a cement plant using SCR denitrification technology = (nitrogen oxide emission concentration after SNCR + increase in nitrogen oxide emission concentration caused by nitrogen in raw materials) * (1 - denitrification efficiency of SCR method)

[0055] Example 1

[0056] An analysis of nitrogen oxide emissions from a factory in Zhejiang Province revealed that the emissions exceeded the standard (more than 100 mg / m³). 3 The reason is...

[0057] Step 1:

[0058] Take 10.0g of raw meal powder entering the kiln from the cement clinker production line.

[0059] Step Two:

[0060] The raw materials are loaded into the reaction tube, which has two outlets. One outlet is connected to the atmosphere, and the other outlet is connected to the flue gas analyzer after being cooled naturally through a hose. The reaction temperature is 600℃.

[0061] Step 3:

[0062] The relationship curve between the nitrogen oxide concentration data of the flue gas analyzer and time is shown in the table below.

[0063] The average values ​​of NO and NO2 per minute (in ppm) measured by the flue gas analyzer are summed to obtain ΣNOx (in ppm), and recorded until ΣNOx reaches a constant value, namely ΣNOxmax, while the time T (in min) is recorded.

[0064]

[0065]

[0066]

[0067] ΣNOxmax=396ppm, T=60min

[0068] Step Four:

[0069] 1) Average NOx concentration of the flue gas entering the flue gas analyzer mean NOx mean =ΣNOxmax / T=396 / 60=6.6;

[0070] 2) Given V flue gas analyzer (Flue gas analyzer flow rate, L / min) = 2;

[0071] The total NOx release from the raw materials is calculated by volumetric NOx. volume NOx volume =6.6*60*2 / 1000000=0.000792L;

[0072] 3) Total NOx release from raw materials (molar amount of NOx) mol NOx mol =NOx volume / 22.4=0.000792 / 22.4=3.73771*10^(-7)mol;

[0073] 4) The total NOx release from the raw materials by mass. quality NOx quality =NOx mol *46=3.73771*

[0074] 10^(-7)*46=0.001626g;

[0075] 5) The amount of nitrogen oxides (NOx) released per unit mass of raw material raw NOx raw =NOx quality / m*10^9=0.001626 / 10.0*10^9=162600mg / t.

[0076] Step 5:

[0077] The standard state flue gas volume V corresponding to one ton of clinker flue gas Take 2000m 3 / t.cl; Raw meal to clinker mass ratio X = 1.6; Increase in nitrogen oxide emission concentration caused by nitrogen in raw meal ΔNOx = NOx raw / V flue gas *X=162600 / 2000*1.6=130.11mg / m 3 The result is rounded to the nearest integer, 130 mg / m³. 3 .

[0078] Nitrogen oxide emission concentration at a cement plant = nitrogen oxide emission concentration after SNCR + increase in nitrogen oxide emission concentration caused by nitrogen in raw materials;

[0079] The minimum emission concentration of nitrogen oxides after SNCR is taken as 40 mg / m³. 3 The nitrogen oxide emission concentration of the cement plant = 40 + 130 = 170 mg / m³ 3 Exceeding 100 mg / m 3 This does not meet environmental protection requirements. Actual test values ​​show the plant's nitrogen oxide emission concentration is 160 mg / m³. 3 Around [a certain value], there is a problem of exceeding the standard. That is, the concentration of nitrogen oxides emitted from the raw materials is too high, resulting in exceeding the standard.

[0080] Further analysis is needed to determine which raw materials caused the excessive increase in nitrogen oxide emissions due to nitrogen in the raw materials.

[0081] The components of the raw materials fed into the kiln were tested sequentially using the methods described above, and the test results are shown in the table below:

[0082]

[0083] The discrepancy between the sum of the results from the individual tests and the results from the raw meal fed into the kiln is due to sampling factors. The test results show that shale, which accounts for only 10% of the raw meal by mass, contributes as much as 77.2% to the increase in nitrogen oxide emission concentration. Therefore, shale is the main cause of nitrogen oxide emissions exceeding the standard (over 100 mg / m³). 3 The main reason is that after replacing the shale from the new source, the amount of nitrogen oxides released per unit mass of feedstock (NOxraw, mg / t) is less than 100,000. The increase in nitrogen oxide emission concentration caused by nitrogen in the feedstock is approximately 40 mg / m³. 3 The plant's nitrogen oxide emissions concentration has been reduced to below 100 mg / m³. 3 The goal.

[0084] The plant later considered adding a medium-temperature SCR system to reduce nitrogen oxide emissions, aiming to control the nitrogen oxide emission concentration to below 70 mg / m³. 3 The denitrification efficiency of the medium-temperature SCR system is considered to be 80%. We would like to inquire whether the aforementioned shale can be used.

[0085] The nitrogen oxide emission concentration of a cement plant using SCR denitrification technology = (nitrogen oxide emission concentration after SCR + increase in nitrogen oxide emission concentration caused by nitrogen in raw materials) * (1 - denitrification efficiency of SCR) = (40 + 130) * (1 - 80%) = 34 mg / m³ 3 To meet the requirement of controlling to 70mg / m³ 3 Therefore, it is determined that the aforementioned shale can be used after adopting SCR denitrification technology.

[0086] Example 2

[0087] A factory in Zhejiang Province plans to reduce ammonia consumption and lower nitrogen oxide emission concentrations below 100 mg / m³ by retrofitting its non-linear catalytic cracking (SNCR) system. 3 The raw feed powder fed into the kiln was analyzed. Following the analytical process described in Example 1, the increase in nitrogen oxide emission concentration caused by nitrogen in the raw material was found to be 30.1 mg / m³. 3 The minimum emission concentration of nitrogen oxides after SNCR is set at 40 mg / m³. 3 The nitrogen oxide emission concentration from the cement plant is 40 + 30.1 = 70.1 mg / m³. 3 Below or above 100 mg / m 3 The plant meets environmental protection requirements and can be upgraded. After the upgrade, the measured nitrogen oxide emission concentration at the cement plant is 60-80 m³ / m³. 3 This meets environmental protection requirements.

[0088] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A system for measuring the amount of nitrogen oxides released from cement raw materials in a preheater, characterized in that: The system includes a heating furnace; each of the furnace's inlet and outlet is connected to a reaction tube via a flange, with the inlet reaction tube open to the atmosphere and the other reaction tube connected to a flue gas analyzer after natural cooling via a flexible hose; an open container is placed inside the furnace for holding raw materials; furthermore, the furnace is equipped with a temperature sensing element connected to an external temperature controller. The use of this system includes the following steps: Step 1: Take the raw materials from the cement clinker production line and weigh them; Step 2: Load the raw materials into the reaction tubes and install the reaction tubes. One reaction tube is connected to the atmosphere, and the other is connected to the flue gas analyzer after being cooled naturally through a hose. Step 3: Record the relationship curve between the nitrogen oxide concentration data of the flue gas analyzer and time. In step 3, the values ​​of NO and NO2 measured by the flue gas analyzer per minute are summed to obtain ΣNOx. This is recorded until ΣNOx reaches a constant value, i.e., ΣNOxmax. At the same time, the time T is recorded in minutes. Step four: Using the relationship curve of nitrogen oxide concentration data versus time from the flue gas analyzer, the flue gas flow rate from the flue gas analyzer, and the mass of the raw material, calculate the amount of nitrogen oxides released per unit mass of raw material; the process of obtaining the amount of nitrogen oxides released per unit mass of raw material is as follows: 1) Calculate the average NOx concentration of the flue gas entering the flue gas analyzer. mean NOx mean = ΣNOxmax / T; 2) Calculate the total NOx release volume from the raw materials. volume NOx volume = NOx mean * T *V flue gas analyzer / 1000000; where V flue gas analyzer The flow rate of the flue gas analyzer; 3) Calculate the total amount of NOx released from the raw materials. mol NOx mol = NOx volume / 22.4; 4) Calculate the total NOx release from the raw materials by mass. quality NOx quality = NOx mol *46; 5) Calculate the amount of nitrogen oxides (NOx) released per unit mass of raw material. raw NOx raw = NOx quality / m * 10^9; where m is the mass of the raw material; Step 5: Divide the amount of nitrogen oxides released per unit mass of raw material by the standard state flue gas volume corresponding to that unit mass of raw material to obtain the increase in nitrogen oxide emission concentration caused by nitrogen in the raw material. Further analysis is needed to determine which raw material caused the excessive increase in nitrogen oxide emission concentration. The increase in nitrogen oxide emission concentration caused by nitrogen in the raw material, ΔNOx = NOx raw / V flue gas * X, V flue gas X represents the standard state flue gas volume corresponding to one ton of clinker, and X is the mass ratio of the raw material to the clinker.

2. A method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system described in claim 1, characterized in that: Includes the following steps: Step 1: Take the raw materials from the cement clinker production line and weigh them; Step 2: Load the raw materials into the reaction tubes and install the reaction tubes. One reaction tube is connected to the atmosphere, and the other is connected to the flue gas analyzer after being cooled naturally through a hose. Step 3: Record the relationship curve between the nitrogen oxide concentration data of the flue gas analyzer and time; Step 4: Calculate the amount of nitrogen oxides released per unit mass of raw material by using the relationship curve between nitrogen oxide concentration data and time from the flue gas analyzer, the flue gas flow rate from the flue gas analyzer, and the mass of the raw material. Step 5: Divide the amount of nitrogen oxides released per unit mass of raw material by the standard state flue gas volume corresponding to that unit mass of raw material to obtain the increase in nitrogen oxide emission concentration caused by nitrogen in the raw material.

3. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: In step one, if a single component of the cement raw meal is used, the component must be crushed and ground to the same fineness as the cement raw meal powder entering the kiln.

4. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: In step two, the reaction temperature in the reaction tube is 600-770℃.

5. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: In step three, the NO and NO2 values ​​measured by the flue gas analyzer per minute are summed to obtain ΣNOx. This summation continues until ΣNOx reaches a constant value, namely ΣNOxmax. At the same time, the time T is recorded in minutes.

6. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: In step four, the process of obtaining the amount of nitrogen oxides released per unit mass of raw material is as follows: 1) Calculate the average NOx concentration of the flue gas entering the flue gas analyzer. mean NOx mean = ΣNOxmax / T; 2) Calculate the total NOx release volume from the raw materials. volume NOx volume = NOx mean * T *V flue gas analyzer / 1000000; where V flue gas analyzer The flow rate of the flue gas analyzer; 3) Calculate the total amount of NOx released from the raw materials. mol NOx mol = NOx volume / 22.4; 4) Calculate the total NOx release from the raw materials by mass. quality NOx quality = NOx mol *46; 5) Calculate the amount of nitrogen oxides (NOx) released per unit mass of raw material. raw NOx raw = NOx quality / m * 10^9; where m is the mass of the raw material.

7. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: In step five, the increase in nitrogen oxide emission concentration caused by nitrogen in the raw materials, ΔNOx = NOx raw / V flue gas * X, V flue gas X represents the standard state flue gas volume corresponding to one ton of clinker, and X is the mass ratio of the raw material to the clinker.

8. The method for determining the amount of nitrogen oxides released from cement raw materials in a preheater using the measuring system as described in claim 2, characterized in that: The predicted nitrogen oxide emission concentration of a cement plant without SCR denitrification technology = the minimum nitrogen oxide emission concentration after SNCR + the increase in nitrogen oxide emission concentration caused by nitrogen in raw materials; The nitrogen oxide emission concentration of a cement plant using SCR denitrification technology = (nitrogen oxide emission concentration after SNCR + increase in nitrogen oxide emission concentration caused by nitrogen in raw materials) * (1 - denitrification efficiency of SCR method).

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