A method for rapidly predicting VOC emission characteristics based on benzene series compound content

Abstract

This invention belongs to the field of environmental monitoring technology for coke oven gas recovery operations in the coking industry, and particularly relates to a method for rapidly predicting VOCs emission characteristics through the content of benzene series compounds. The method is characterized by utilizing the concentration ratio of benzene to toluene to quickly predict the VOCs emission characteristics of the coking process. Specifically, it includes determining sampling points, detecting the concentrations of benzene and toluene, and then performing trend analysis with the benzene-toluene ratio, the sum of benzene series compound concentrations, and the total VOCs concentration as the ordinates to predict and judge the VOCs emission situation at each sampling point in the chemical recovery section of the coking process. Compared with existing technologies, the advantages of this invention are: utilizing the concentration of benzene series compounds, especially the concentration ratio of benzene to toluene, it can quickly predict the VOCs emission characteristics of the coking process and predict and judge the VOCs emission situation at each process in the chemical recovery section of the coking process; it has the advantages of simple operation and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring technology for coke oven gas recovery operation areas in the coking industry, and particularly relates to a method for rapidly predicting VOCs emission characteristics by the content of benzene series compounds. Background Technology

[0002] VOCs (volatile organic compounds) refer to organic compounds that participate in atmospheric photochemical reactions. VOCs are not only important precursors to O3 and PM2.5, but also significant pollutants affecting human health. The coking industry is a major industrial source of VOC emissions. Due to the unique nature of its processes, coking industry VOC emissions are characterized by high concentrations, multiple emission sources, diverse emission types, and difficulties in treatment. Currently, VOC detection methods generally follow the 35 organic compounds specified in standard HJ 644-201 "Determination of Volatile Organic Compounds in Ambient Air - Adsorption Tube Sampling-Thermal Desorption / Gas Chromatography-Mass Spectrometry" or the 24 organic compounds specified in standard HJ 734-2014 "Determination of Volatile Organic Compounds in Stationary Source Exhaust Gas - Solid Phase Adsorption-Thermal Desorption / Gas Chromatography-Mass Spectrometry". In 2017, the Ministry of Environmental Protection issued the "2018 Monitoring Plan for Volatile Organic Compounds in Key Areas of Ambient Air," which formally stipulated the VOCs that need to be detected due to their strong photochemical reactivity or potential impact on human health. These include 117 types of VOCs such as alkanes, alkenes, aromatic hydrocarbons, oxygenated volatile organic compounds (OVOCs), and halogenated hydrocarbons. Among them are 57 types of volatile organic compounds (formerly PAMS substances), 13 types of aldehydes and ketones (OVOCs), and 47 types of other volatile organic compounds (some TO15 substances).

[0003] Aromatic hydrocarbons, as an important component of PAMS gases, have long been a focus of research. The generation and coexistence mechanisms of substances such as benzene, toluene, xylene, and ethylbenzene reveal the formation patterns of VOCs. The benzene / toluene / ethylbenzene / xylene ratio (B / T / E / X) is often used to determine the source of benzene series compounds. BTEX has complex sources, with fossil fuels, vehicle exhaust, and certain industrial processes being the main sources. The B / T value of benzene to toluene is considered an important indicator for identifying the contribution of vehicle exhaust to atmospheric hydrocarbons. The ratio of m-xylene to ethylbenzene can also be used to estimate the lifetime of atmospheric hydrocarbons. Pilar et al. (1973) first proposed using the toluene / benzene concentration ratio to analyze the source of benzene series compounds in the air. The m-xylene / o-xylene ratio can also be used to distinguish the emission characteristics of benzene series compounds from various pollution sources. The B / T ratio in benzene series emissions from motor vehicles is around 0.5 (Perry and Gee, 1995; Brocco et al., 1997). The emissions from the combustion of coal, biomass, and charcoal in power plants range from 1 to 2. He Qiusheng (2006) measured some coke flue gas emissions at around 6.

[0004] Current detection methods require extensive experimental and analytical work, resulting in low timeliness of gas analysis and an inability to quickly respond to VOC emissions from various processes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for rapidly predicting VOC emission characteristics based on the content of benzene series compounds, overcoming the shortcomings of existing technologies. This method utilizes the concentration of benzene series compounds, particularly the benzene-toluene concentration ratio, to quickly predict the VOC emission characteristics of the coking process and forecast and determine the VOC emissions of each step in the chemical recovery section of the coking process. Alternatively, by comparing a trend chart of the benzene-toluene ratio with trend charts of total benzene series compounds and total VOCs, a rapid analysis of the VOC emission characteristics of the chemical recovery section can be achieved.

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

[0007] A method for rapidly predicting VOC emission characteristics based on benzene series compound content is characterized by using the concentration ratio of benzene to toluene to rapidly predict the VOC emission characteristics of the coking process. Specifically, this includes determining sampling points, detecting the concentrations of benzene and toluene, and then performing trend analysis with the benzene to toluene ratio, the sum of benzene series compound concentrations, and the total VOC concentration as the vertical axis to predict and judge the VOC emission situation of each sampling point in the chemical recovery section of the coking process.

[0008] The sampling points are any one or any combination of two or more of the following: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process.

[0009] The detection methods employed are the standards "Determination of Volatile Organic Compounds in Ambient Air - Gas Chromatography-Mass Spectrometry by Canister Sampling" (HJ 759-2015) and "Determination of Aldehydes and Ketones in Ambient Air - High Performance Liquid Chromatography" (HJ683-2014). The standards specify 117 types of VOCs that may affect human health, as outlined in the "2018 Monitoring Plan for Volatile Organic Compounds in Ambient Air in Key Areas" issued by the Ministry of Environmental Protection. These include 57 volatile organic compounds (formerly PAMS substances), 13 aldehydes and ketones (OVOCs), and 47 other volatile organic compounds (some TO15 substances).

[0010] The trend analysis includes calculation and plotting of point trend charts. Trend charts are plotted with each sampling point number as the x-axis and the benzene to toluene ratio, the sum of benzene series compound concentrations, and the total VOCs concentration as the y-axis. The three sets of images are compared and analyzed to obtain the VOCs emission status of each process sampling point. Specifically:

[0011] (1) The formula for the ratio of benzene to toluene is:

[0012]

[0013] In formula (1): R0—the ratio of benzene concentration to toluene concentration, C PhH —The detected benzene concentration, C PhMe —The detected concentration of toluene;

[0014] (2) The formula for the sum of the concentrations of benzene series compounds is:

[0015] ΣPh=C1+C2+C3+···+C n (Formula 2)

[0016] C1, C2, C3 — Concentrations of each benzene series compound, μg / m³ 3 (Formula 3)

[0017] (3) The formula for the total concentration of VOCs is:

[0018] ΣVOCs=C PAMS +C OVOCs +C TO15 (Formula 4)

[0019] In equations (2) and (3): C PAMS —Concentrations of 57 PAMS gases, μg / m³ 3 C OVOCs —Concentrations of 13 aldehydes and ketones, μg / m³ 3 C TO15 —Concentrations of 47 other volatile organic compounds, μg / m³ 3 .

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) By utilizing the concentration of benzene series compounds, especially the concentration ratio of benzene to toluene, the VOC emission characteristics of the coking process can be quickly predicted, and the VOC emission of each process in the chemical recovery section of the coking process can be predicted and judged.

[0022] 2) This invention utilizes a gas analysis and detection instrument to determine the VOC emissions of a process simply by measuring the concentrations of benzene and toluene, which has the advantages of simple operation and high efficiency.

[0023] 3) Alternatively, the trend chart of the benzene to toluene ratio can be compared with the trend charts of the total benzene series compounds and the total VOCs to quickly determine the VOCs emission characteristics of the chemical recovery section. Attached Figure Description

[0024] Figure 1Synchronous trend graphs of the benzene to toluene ratio R0 curve, the total concentration of benzene series compounds ΣPh curve, and the total concentration of VOCs ΣVO curve in Example 1 of this invention;

[0025] Figure 2 Synchronous trend graphs of the benzene to toluene ratio R0 curve, the total concentration of benzene series compounds ΣPh curve, and the total concentration of VOCs ΣVO curve in Example 2 of this invention;

[0026] Figure 3 Synchronous trend graphs of the benzene to toluene ratio R0 curve, the total concentration of benzene series compounds ΣPh curve, and the total concentration of VOCs ΣVO curve in Example 3 of this invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those skilled in the art, other specific embodiments can be obtained based on these specific embodiments without creative effort.

[0029] The components of the embodiments of the invention described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0030] In the following examples, six processes were used as sampling points: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process. The VOCs concentration detection method adopted was the method specified in the standards "Determination of Volatile Organic Compounds in Ambient Air - Gas Chromatography-Mass Spectrometry by Canister Sampling" (HJ 759-2015) and "Determination of Aldehydes and Ketones in Ambient Air - High Performance Liquid Chromatography" (HJ683-2014). The types of organic compounds detected were 117 types of VOCs that may affect human health, as specified in the "2018 Key Area Ambient Air Volatile Organic Compounds Monitoring Plan" issued by the Ministry of Environmental Protection. These included 57 types of volatile organic compounds (formerly PAMS substances), 13 types of aldehydes and ketones (OVOCs), and 47 types of other volatile organic compounds (some TO15 substances).

[0031] Example 1:

[0032] Sampling points were located at six processes in the chemical recovery workshop of a coking plant during windy winter weather: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process. Measurement methods followed national standards. The test data for Example 1 are shown in Table 1, unit μg / m³. 3 .

[0033] Table 1

[0034] name benzene storage tank benzene removal process Desulfurization process Tar tank top ammonium sulfate process Cold drum process benzene concentration 104.46 1180.66 2039.35 128.06 251.41 1598.74 Toluene concentration 311.67 317.73 793.61 308.40 377.98 555.26 <![CDATA[Ratio R0]]> 0.33 3.72 2.57 0.42 0.66 2.88 Total value of benzene series compounds 488.80 1570.09 2914.35 493.44 696.981 2279.79 Total VOCs 10903.24 20666.12 40165.08 8800.83 21335.14 32203.66

[0035] See trend chart Figure 1 The trends in the benzene-to-toluene ratio, total benzene concentration, and total VOCs concentration are largely consistent. Due to the unique nature of the benzene removal process, at other sampling points, when the R0 value is greater than 1 (i.e., the benzene concentration is higher than the toluene concentration), the concentrations of both benzene series compounds and total VOCs are relatively high; when the R0 value is less than 1 (i.e., the benzene concentration is lower than the toluene concentration), the concentrations of both benzene series compounds and total VOCs are relatively normal. Therefore, based on the R0 value trend chart, the emission characteristics and total concentrations of each process can be basically determined.

[0036] Example 2:

[0037] Sampling points were located at six processes in the chemical recovery workshop of a coking plant under clear autumn weather conditions: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process. Measurement methods followed national standards. The test data for Example 2 are shown in Table 2, with units of μg / m³. 3 .

[0038] Table 2

[0039] name benzene storage tank Desulfurization process Tar tank top ammonium sulfate process Cold drum process benzene concentration 32.82 677.78 40.68 81.80 530.91 Toluene concentration 108.89 269.53 107.80 130.99 190.08 Ratio R0 0.30 2.51 0.37 0.62 2.79 Total value of benzene series compounds 162.93 971.45 164.48 232.32 759.93 Total VOCs 12390.05 45642.13 10000.94 21971.76 36595.07

[0040] See trend chart Figure 2 Almost identical to Example 1, although the light wind conditions in Example 1 reduced the total VOCs concentration, the trend represented by the R0 value is almost the same. The emission characteristics and total concentration characteristics of each process can still be determined based on the trend graph of the R0 value.

[0041] Example 3:

[0042] Sampling points were located at six processes in the chemical recovery workshop of a coking plant during windy winter weather: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process. Measurement methods followed national standards. The test data for Example 3 are shown in Table 3, with units of μg / m³.

[0043] Table 3

[0044] name benzene storage tank benzene removal process Desulfurization process Tar tank top ammonium sulfate process Cold drum process benzene concentration 29.02 244.63 566.49 35.57 69.83 444.10 Toluene concentration 61.11 62.30 155.61 60.47 74.11 108.88 <![CDATA[Ratio R0]]> 0.47 3.93 3.64 0.59 0.94 4.08 Total value of benzene series compounds 116.38 436.14 693.89 117.49 165.95 21642.25 Total VOCs 7327.45 13888.52 26992.66 5914.54 14338.14 633.28

[0045] See trend chart Figure 3The results show that the consistency requirements are basically met, but the R0 value is higher due to the unique nature of the benzene removal process. Because it was windy winter weather, the overall VOC emissions were low, but still largely in line with the predicted trend of the R0 value.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for rapidly predicting VOCs emission characteristics based on benzene series compound content, characterized in that, By using the concentration ratio of benzene to toluene, the VOC emission characteristics of the coking process can be quickly predicted. Specifically, this includes determining the sampling points, detecting the concentrations of benzene and toluene, and then performing trend analysis with the benzene to toluene ratio, the sum of benzene series concentrations, and the total VOC concentration as the vertical axis to predict and judge the VOC emission of each sampling point in the chemical recovery section of the coking process. The sampling points are any one or any combination of two or more of the following: benzene storage tank, benzene removal process, desulfurization process, tar tank top, ammonium sulfate process, and cold drum process; The trend analysis includes calculation and plotting of point trend charts. Trend charts are plotted with each sampling point number as the x-axis and the benzene to toluene ratio, the sum of benzene series compound concentrations, and the total VOCs concentration as the y-axis. The three sets of images are compared and analyzed to obtain the VOCs emission status of each process sampling point. Specifically: (1) The formula for the benzene to toluene ratio is: (Official 1) In formula (1): R0 -- the ratio of benzene concentration to toluene concentration, C PhH --Detected benzene concentration, C PhMe --Detected toluene concentration; (2) The formula for the sum of the concentrations of benzene series compounds is: (Official 2) C1, C2, C3 -- Concentrations of each benzene series compound, μg / m³ 3 (Formula 3) (3) The formula for the total concentration of VOCs is: (Official 4) In equations (2) and (3): C PAMS --Concentrations of 57 PAMS gases, μg / m³ 3， C OVOCs --Concentration of 13 aldehydes and ketones, μg / m³ 3， C TO15 --Concentrations of 47 other volatile organic compounds, μg / m³ 3 ; Excluding the benzene removal process due to its unique characteristics, at other points, when the R0 value is >1, that is, when the benzene concentration is higher than the toluene concentration, the concentrations of benzene series compounds and the total VOCs are both high; when the R0 value is <1, that is, when the benzene concentration is lower than the toluene concentration, the concentrations of benzene series compounds and the total VOCs are relatively normal. Therefore, based on the trend chart of the R0 value, the emission characteristics of VOCs in each process can be determined.

2. The method for rapidly predicting VOCs emission characteristics based on benzene series compound content according to claim 1, characterized in that, The detection method used is the method specified in the standard "Determination of Volatile Organic Compounds in Ambient Air by Gas Chromatography-Mass Spectrometry (HJ759-2015)" and the standard "Determination of Aldehydes and Ketones in Ambient Air by High Performance Liquid Chromatography (HJ683-2014)".

3. The method for rapidly predicting VOCs emission characteristics based on benzene series compound content according to claim 1, characterized in that, The standard used for the test includes 117 types of volatile organic compounds that may affect human health, as specified in the "2018 Monitoring Plan for Volatile Organic Compounds in Ambient Air of Key Areas" issued by the Ministry of Environmental Protection. These include 57 volatile organic compounds (formerly PAMS substances), 13 aldehydes and ketones (OVOCs), and 47 other volatile organic compounds (some TO15 substances).

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