A device and method for measuring the concentration of ammonia gas in boiler exhaust gas using the DTW algorithm and pH meter

Abstract

The present invention relates to an apparatus and method for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter capable of determining the presence or absence of ammonia leakage and the increase or decrease in concentration, comprising: an enclosure having an exhaust gas inlet formed on one side and an exhaust gas outlet formed on the other side; a water spray nozzle installed on one side of the upper portion of the enclosure to spray water onto the exhaust gas passing through the interior of the enclosure to generate an aqueous solution; and a measuring sensor installed on one side of the lower portion of the enclosure to measure the pH of the generated aqueous solution collected at the bottom of the enclosure, and further comprising the steps of: acquiring SOx time series data, NOx time series data, and pH time series data from the measuring sensor (130) that measures the pH of the aqueous solution generated by mixing exhaust gas and water; acquiring each time series data at 5-second intervals and calculating the average value of the time series data; and normalizing the minimum-maximum of the unit for each time series data. The method includes a step of calculating the DTW distance between SOx time series data and pH time series data, and between NOx time series data and pH time series data after the normalization process; and a step of determining the concentration by summing the distances calculated in the step of calculating the DTW distance and comparing the pH time series data value with the SOx time series data value and the NOx time series data value.

Description

Technology Field

[0001] The present invention relates to an apparatus and method for measuring ammonia gas concentration in boiler flue gas using a Dynamic Time Warping (DTW) algorithm and a pH meter, and more specifically, to an apparatus and method for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter that can determine the presence or absence of ammonia leakage and the increase or decrease in concentration. Background Technology

[0002] Generally, ammonia is composed of nitrogen and hydrogen, making it an eco-friendly fuel that does not emit carbon dioxide during combustion. To reduce the emission of carbon dioxide, a greenhouse gas, existing coal-fired power plants intend to use ammonia as fuel instead of coal.

[0003] Domestic research projects have been underway since 2021 with the goal of 20% ammonia co-firing in 500MW class coal-fired power plants by 2025. Since 500MW coal-fired power plants consume 2,000 to 3,000 tons of coal, the amount of ammonia used is expected to increase significantly in the future, and the importance of developing ammonia-related technologies is growing.

[0004] Because ammonia is a toxic and corrosive gas, complete combustion must occur within the boilers of coal-fired power plants, and if ammonia is not completely combusted and is released into the atmosphere, it can threaten the safety of workers in nearby areas.

[0005] In addition, if complete combustion does not occur, ammonia can cause corrosion of the heat exchange tubes inside the boiler, and if the fuel does not burn, thermal efficiency will also decrease.

[0006] If ammonia concentration is measured in real time, immediate action can be taken in the event of a leak, and the aforementioned safety, boiler corrosion, and economic issues can be prevented.

[0007] Real-time ammonia measurement technologies are broadly classified into five categories as follows.

[0008] First, the electrochemical method measures the concentration of a gas by measuring the current generated when ammonia reacts with an electrode.

[0009] Second, the metal oxide operates by detecting changes in the electrical conductivity of the metal oxide film when in contact with ammonia, and the metal oxide sensor is very sensitive and can detect ammonia concentrations as low as one part in billions.

[0010] Third, photoionization is a method of calculating concentration by measuring the ionization of ammonia gas molecules when exposed to ultraviolet light; when ammonia molecules are ionized, they generate a measurable electrical signal, which is used to determine the concentration of ammonia in the atmosphere.

[0011] Fourth, the infrared method is a method of measuring the absorption of infrared radiation by ammonia molecules.

[0012] Fifth, the catalytic method is a method that calculates the concentration by measuring the catalytic oxidation of ammonia over a heated catalyst.

[0013] The ammonia concentration measurement methods described above have four major disadvantages.

[0014] First, the price ranges from 50 to 80 million won per device, and in the case of FT-IR (infrared method), it is very high, ranging from 200 to 300 million won.

[0015] Second, it requires high repair costs and time.

[0016] Third, since moisture and ash remaining from burnt coal entering the measuring device can cause malfunctions, gas pretreatment using moisture traps and dust removal filters is required before measurement.

[0017] Fourth, in the case of the electrochemical method, prolonged exposure to ammonia damages the sensor, and since re-measurement is required after a few minutes of measurement, long-term measurement is difficult. Prior art literature

[0018] Japanese Registered Patent Publication No. 6025504 (October 21, 2016) The problem to be solved

[0019] The objective of the present invention is to provide an apparatus and method for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, which is devised in consideration of existing problems and allows for easy verification of whether power plant equipment is operating normally by identifying the presence or absence of ammonia leakage and the increase or decrease in concentration, while also enabling low measurement costs, easy maintenance, and the prevention of environmental pollution by blocking ammonia emissions from the power plant. means of solving the problem

[0020] A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter according to an embodiment of the present invention for solving the above technical problem comprises: an enclosure having an exhaust gas inlet formed on one side and an exhaust gas outlet formed on the other side; a water spray nozzle installed on one side of the upper portion of the enclosure to spray water into the exhaust gas passing through the interior of the enclosure to generate an aqueous solution; and a measuring sensor installed on one side of the lower portion of the enclosure to measure the pH of the generated aqueous solution collected at the bottom of the enclosure.

[0021] The exhaust gas inlet is characterized by being formed to open horizontally at the top of one side of the enclosure.

[0022] The exhaust gas outlet is characterized by being formed to open vertically on the upper surface of the other side of the outer casing at a certain distance from the exhaust gas inlet.

[0023] The above-mentioned enclosure is characterized by having a partition installed on one side of the interior to ensure a residence time when the exhaust gas flowing into the enclosure through the exhaust gas inlet and the water sprayed from the water spray nozzle are mixed.

[0024] The above bulkhead is characterized by having an up-and-down zigzag shape installed between the exhaust gas inlet and the center of the enclosure within the enclosure.

[0025] It is characterized in that a water spray nozzle is installed on the upper part of the outer casing at each of the upper and lower zigzag-shaped partitions.

[0026] It is characterized by having a water discharge port formed at the bottom of the outer casing between each of the upper and lower zigzag-shaped partitions.

[0027] The above enclosure is characterized by having a water pipe for spraying water for cleaning inside the enclosure installed on the upper central side of the enclosure.

[0028] The lower part of the above-mentioned outer casing is characterized by having a funnel-shaped inclined surface that narrows toward the center of the lower portion to collect the generated aqueous solution flowing down from the spray water pipe or the water outlet.

[0029] The above-mentioned measuring sensor is installed within the inclined surface to measure the pH from the generated aqueous solution collected in the inclined surface, and the measuring sensor is electrically connected to a measuring signal line penetrating one side of the enclosure.

[0030] It is characterized by the installation of an overflow water pipe at a certain height on one side of the inclined surface to discharge the generated aqueous solution collected on the inclined surface.

[0031] Meanwhile, a method for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter according to an embodiment of the present invention comprises: a step of acquiring SOx time series data, NOx time series data, and pH time series data from a measuring sensor (130) that measures the pH of an aqueous solution generated by mixing flue gas and water; a step of acquiring each time series data at 5-second intervals and calculating the average value of the time series data; a step of normalizing the minimum-maximum unit of each time series data; a step of calculating the DTW distance between the SOx time series data and the pH time series data, and between the NOx time series data and the pH time series data after the normalization process; and a step of determining the concentration by summing the distances calculated in the step of calculating the DTW distance and comparing the pH time series data value with the SOx time series data value and the NOx time series data value.

[0032] The above DTW distance is a dimensionless number and is characterized by calculating the increase in ammonia concentration based on 30%, 20%, and 10%.

[0033] Correlation between the pH time series data value, the SOx time series data value, and the NOx time series data value for calculating the DTW distance ( ) is a mathematical expression

[0034] It is characterized by being defined as (where di,j is the previous distance, and the 3 components within the min function are components in the positive direction). Effects of the invention

[0035] The apparatus and method for measuring ammonia gas concentration in boiler flue gas using the DTW algorithm and pH meter of the present invention have the following effects.

[0036] First, while existing ammonia measuring devices are expensive and difficult to maintain, the pH measuring device of the present invention is inexpensive.

[0037] Second, although the present invention has the disadvantage of being difficult to determine the exact numerical value of ammonia concentration, it is sufficient for blocking ammonia emissions in power plants, etc., as it is possible to determine the presence or absence of ammonia leakage and the increase or decrease in concentration.

[0038] Third, since power plant exhaust gas contains moisture and ash remaining from burning coal, pretreatment facilities such as moisture removal devices and ash removal filters are essential for using conventional gas analyzers; however, the pH meter of the present invention operates normally even in contaminated environments and has a low failure rate.

[0039] Fourth, since the pH meter of the present invention is used not only for experimental purposes but also for general purposes, purchasing and replacing the product is easy, and maintenance is easy in the event of a malfunction. Brief explanation of the drawing

[0040] FIG. 1 is an exploded example diagram illustrating an ammonia gas concentration measuring device in boiler flue gas utilizing a DTW algorithm and a pH meter according to the present invention. FIG. 2 is a side interior example view illustrating an ammonia gas concentration measuring device in boiler flue gas utilizing a DTW algorithm and a pH meter according to the present invention. Figure 3 is a correlation diagram between the DTW algorithm according to the present invention and NOx, SOx, and ammonia concentrations. Figure 4 is a comparison diagram of correlation analysis results with and without the application of the DTW algorithm according to the present invention. FIG. 5 is an example diagram of a DTW algorithm distance calculation according to the present invention. FIG. 6 is a flowchart for measuring ammonia concentration using the DTW algorithm according to the present invention. Specific details for implementing the invention

[0041] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, FIGS. 1 to 6, in order to fully understand the present invention. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described in detail below. It should be noted that in each drawing, identical components may be illustrated with the same reference numerals. Detailed descriptions of known functions and components that are deemed to unnecessarily obscure the essence of the present invention are omitted.

[0042] Referring to FIGS. 1 and 2, a device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter according to an embodiment of the present invention comprises an exhaust gas inlet (110), an exhaust gas outlet (120), a measuring sensor (130), a water pipe for spraying (140), a water pipe for overflow (150), a partition wall (160), a water spray nozzle (170), and a water discharge port (180) installed in an enclosure (100).

[0043] That is, the lower part of the above-mentioned outer casing (100) is formed with a funnel-shaped inclined surface (102) that becomes narrower towards the center of the lower part so that the generated aqueous solution flowing down from the spray water pipe (140) or water outlet (180) is collected.

[0044] The exhaust gas inlet (110) is formed to be horizontally opened at the top of one side of the outer casing (100).

[0045] The exhaust gas outlet (120) is formed to open vertically on the upper surface of the other side of the outer casing (100) at a certain distance from the exhaust gas inlet (110).

[0046] The above-mentioned measuring sensor (130) is installed at the lower center of the inclined surface (102) to measure the pH of the generated aqueous solution collected on the inclined surface (102) with respect to one side of the lower part of the enclosure (100), and one side of the measuring sensor (130) is electrically connected to a measuring signal line (132) that penetrates one side of the enclosure (100).

[0047] The above spray water pipe (140) is installed to penetrate the upper center of the outer casing (100) and face the inside of the outer casing (100), and serves to clean the inside of the outer casing (100).

[0048] The above-mentioned overflow water pipe (150) is installed at a certain height on one side of the inclined surface (102) and serves to discharge the generated aqueous solution collected on the inclined surface (102).

[0049] The above partition (160) is installed on one side inside the outer casing (100) and serves to secure a residence time when the exhaust gas flowing into the outer casing (100) through the exhaust gas inlet (110) and the water sprayed from the water spray nozzle (170) are mixed.

[0050] At this time, it is preferable that the above bulkhead (160) be configured in an up-and-down zigzag shape installed between the exhaust gas inlet (110) and the center of the outer casing (100) within the outer casing (100).

[0051] The above water spray nozzle (170) is installed on the upper part of the outer casing (100) at each interval between the upper and lower zigzag-shaped partitions (160) and serves to evenly spray water onto the exhaust gas passing through the zigzag-shaped passages of the partitions (160).

[0052] The above water discharge port (180) is formed at the bottom of the outer casing (100) at each of the upper and lower zigzag-shaped partitions (160) and serves to discharge the aqueous solution generated by the mixing of water and exhaust gas flowing down the zigzag-shaped passage of the partition (160) to the inclined surface (102).

[0053] Referring to FIGS. 3 to 6, a method for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter according to an embodiment of the present invention comprises: a step of acquiring SOx time series data, NOx time series data, and pH time series data from a measuring sensor (130) that measures the pH of an aqueous solution generated by mixing exhaust gas and water in a boiler flue gas ammonia gas concentration measuring device; a step of acquiring each time series data at 5-second intervals and calculating the average value of the time series data; a step of normalizing the minimum-maximum unit of each time series data; a step of calculating the DTW distance between the SOx time series data and the pH time series data, and between the NOx time series data and the pH time series data after the normalization process; and a step of determining the concentration by summing the distances calculated in the step of calculating the DTW distance and comparing the pH time series data value with the SOx time series data value and the NOx time series data value.

[0054] At this time, when the pH of the above-mentioned aqueous solution is measured, it shows an acidic value as shown in the reaction equation below due to NO2 (nitrogen oxides) and SO3 (sulfur oxides) in the exhaust gas.

[0055] In other words, while nitrogen oxides and sulfur oxides in exhaust gas are environmentally regulated substances and are measured in real-time at power plants, in the absence of ammonia in the exhaust gas, nitrogen oxides and sulfur oxides become the primary factors determining pH.

[0056]

[0057] Here, when there is no ammonia in the exhaust gas, as shown in Figure 3, the pH value is only affected by nitrogen oxides and sulfur oxides, and the concentrations of nitrogen oxides and sulfur oxides have a high correlation with the pH value, so the result of the DTW algorithm is calculated to be low.

[0058] In addition, when ammonia is present in the gas, as shown in Figure 3, the influence of nitrogen oxides and sulfur oxides on the pH value decreases and the influence of ammonia increases, so the result of the DTW algorithm is higher.

[0059] In other words, if the correlation between variables is high, the result of the DTW algorithm decreases, and if the correlation between variables decreases, the result of the DTW algorithm increases.

[0060] As such, since the correlation values ​​between SOx, NOx, and pH vary depending on the ammonia concentration in the flue gas, the ammonia concentration can be indirectly determined through this.

[0061] Also, DTW (Dynamic Time Warping) is an algorithm for comparing similarity between time series data. DTW can measure similarity by taking into account differences in length or speed between time series data, and DTW can be used for all sequence data in the form of time series.

[0062] That is, as shown in Figure 4, when the DTW algorithm is not applied, the similarity is high, but for data with a time difference, the correlation is calculated to be low.

[0063] However, when applying the DTW algorithm, a high correlation can be calculated for similar data even if there is a time difference.

[0064] The above DTW distance is a dimensionless number, and the increase in ammonia concentration is calculated based on 30%, 20%, and 10%.

[0065] At this time, the distance function of DTW is based on the following criteria.

[0066] First, boundary condition: the first and last of the distances must be connected.

[0067] Second, Continuity: Distance paths must be restricted to adjacent cells that include diagonal elements.

[0068] Third, monotonicity: The distance path must not move in the negative direction.

[0069] Correlation between the pH time series data value, the SOx time series data value, and the NOx time series data value for calculating the DTW distance ( ) is a mathematical expression

[0070]

[0071] Here, di,j is the previous distance, and the 3 components within the min function are components in the positive direction.

[0072] Figure 5 is an example diagram of DTW calculated using X-axis and Y-axis data,

[0073] First, move from the top right (start point) to 1, as the smallest component in the diagonal downward direction (3 components) is 1.

[0074] Second, select diagonal component 1 from the diagonal downward direction (1,1,3) in the next component (select diagonal component if sizes are the same).

[0075] Fifth, likewise, select the 1st component of the diagonal among the 1,1,3 components.

[0076] Fourth, repeat the path selection until the bottom left (end point).

[0077] Fifth, the DTW distance is calculated as 6 (1+1+1+1+1+1).

[0078] Meanwhile, the present invention is not limited to the embodiments described above, but can be implemented with modifications and variations within the scope of the essence of the invention, and such technical concepts to which modifications and variations are applied should also be considered to fall within the scope of the following patent claims. Explanation of the symbols

[0079] 100 : Enclosure 102 : Inclined surface 110: Exhaust gas inlet 120: Exhaust gas outlet 130 : Measurement sensor 132 : Meter signal line 140 : Water pipe for spray 150 : Water pipe for overflow 160 : Bulkhead 170 : Water spray nozzle 180 : Water drain

Claims

Claim 1 An outer casing (100) having an exhaust gas inlet (110) formed on one side and an exhaust gas outlet (120) formed on the other side; a water spray nozzle (170) installed on one side of the upper portion of the outer casing (100) to spray water into the exhaust gas passing through the inside of the outer casing (100) to produce an aqueous solution; A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized by calculating an average value from SOx time series data, NOx time series data, and pH time series data from the measurement sensor (130), normalizing the minimum-maximum unit for each time series data, calculating the DTW (Dynamic Time Warping) distance between the SOx time series data and the pH time series data, and between the NOx time series data and the pH time series data, summing the calculated DTW distances, and comparing the pH time series data value with the SOx time series data value and the NOx time series data value to determine the concentration. Claim 2 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 1, the exhaust gas inlet (110) is formed to be horizontally opened at the top of one side of the outer casing (100). Claim 3 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 1, the exhaust gas outlet (120) is formed to be vertically opened on the upper surface of the other side of the outer casing (100) at a certain distance from the exhaust gas inlet (110). Claim 4 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 1, a partition wall (160) is installed on one side inside the outer casing (100) to secure a residence time when the exhaust gas flowing into the outer casing (100) through the exhaust gas inlet (110) and the water sprayed from the water spray nozzle (170) are mixed. Claim 5 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, wherein, in claim 4, the partition wall (160) is in an up-and-down zigzag shape installed between the exhaust gas inlet (110) and the center of the outer casing (100) with respect to the interior of the outer casing (100). Claim 6 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 5, a water spray nozzle (170) is installed on the upper part of the outer casing (100) at each of the upper and lower zigzag partitions (160). Claim 7 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 5, a water discharge port (180) is formed at the bottom of the outer casing (100) at each of the upper and lower zigzag-shaped partitions (160). Claim 8 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 7, a water pipe (140) for spraying for cleaning inside the enclosure (100) is installed on the central upper side of the enclosure (100). Claim 9 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 8, the lower part of the outer casing (100) is formed with a funnel-shaped inclined surface (102) that becomes narrower towards the center of the lower part so that the generated aqueous solution flowing down from the spray water pipe (140) or the water outlet (180) is collected. Claim 10 A device for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 9, the measuring sensor (130) is installed within the inclined surface (102) to measure the pH from the generated aqueous solution collected in the inclined surface (102), and the measuring sensor (130) is electrically connected to a measuring signal line (132) penetrating one side of the outer casing (100). Claim 11 A device for measuring the concentration of ammonia gas in boiler flue gas using a DTW algorithm and a pH meter, characterized in that, in claim 9, an overflow water pipe (150) is installed at a certain height on one side of the inclined surface (102) to discharge the generated aqueous solution collected on the inclined surface (102). Claim 12 A method for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter, comprising: a step of acquiring SOx time series data, NOx time series data, and pH time series data from a measuring sensor (130) that measures the pH of an aqueous solution generated by mixing exhaust gas and water; a step of acquiring each time series data at 5-second intervals and calculating the average value of the time series data; a step of normalizing the minimum-maximum unit of each time series data; a step of calculating the DTW distance between the SOx time series data and the pH time series data, and between the NOx time series data and the pH time series data after the normalization process; a step of summing the distances calculated in the step of calculating the DTW distance; and a step of determining the concentration by comparing the pH time series data value with the SOx time series data value and the NOx time series data value. Claim 13 A method for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter, wherein, in claim 12, the DTW distance is a dimensionless number and the increase in ammonia concentration is calculated based on 30%, 20%, and 10%. Claim 14 In claim 12, the correlation between the pH time series data value, the SOx time series data value, and the NOx time series data value for calculating the DTW distance ( ) is a mathematical expression A method for measuring ammonia gas concentration in boiler flue gas using a DTW algorithm and a pH meter, characterized by being defined as (where di,j is the previous distance, and the three components within the min function are components in the positive direction).

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