Deodorization control system and deodorization control method

Abstract

To provide a deodorization control system that enables safe treatment even when combustible odor gas is contained and that can discharge gas at safe temperature.SOLUTION: A deodorization control system includes: a dilution section that includes a dilution damper for taking in dilution gas for diluting exhaust gas containing odor gas and allows the exhaust gas to pass therethrough while diluting it by the dilution gas; a first temperature sensor that detects a temperature of the exhaust gas passing through the dilution section; an oxidation treatment section that performs high-temperature oxidation treatment of the odor gas by heating the exhaust gas with a burner; an air exhaust section that guides the exhaust gas to outside; a second temperature sensor that detects a temperature of the exhaust gas; a heat exchanger that recovers heat from the exhaust gas in the air exhaust section; and a control section. The control section controls the dilution damper on the basis of an odor gas concentration in the exhaust gas and a temperature of the exhaust gas detected by the first temperature sensor so that the odor gas concentration is less than an explosion lower limit, and performs control on the basis of the temperature of the exhaust gas detected by the second temperature sensor so that the exhaust gas maintains a predetermined temperature range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a deodorization control system and a deodorization control method. [Background technology]

[0002] Conventional deodorization control systems for deodorizing exhaust gases include a deodorizing furnace (see Patent Document 1), which introduces and heats the dried exhaust gas and dry distillation gas generated in a dryer and a carbonization furnace that constitute a combustible waste treatment system into a combustion chamber to pyrolyze the malodorous components in these gases. In this deodorizing furnace, an inlet for the dried exhaust gas and / or dilution air from the dryer, an inlet for dry distillation gas, and an auxiliary burner are installed in this order from the bottom of the combustion chamber upward, at different heights. When the dried exhaust gas flows in through an inlet opening near the bottom of the combustion chamber, dilution air is injected, and the temperature inside the combustion chamber is continuously measured using a thermocouple or similar device. The temperature inside the combustion chamber is controlled by increasing or decreasing the amount of dilution air injected so that the temperature inside the combustion chamber reaches approximately 800°C, the temperature required to pyrolyze the malodorous components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-300350 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the deodorizing furnace of Patent Document 1, dilution gas is injected from the outside air to control the temperature, but the gas components and concentration are not controlled, which makes it difficult to continue to safely treat flammable gases such as benzene and toluene.

[0005] The present invention has been made in view of the problems inherent in the prior art, and an object of the present invention is to provide a deodorization control system that deodorizes exhaust gases containing odorous gases discharged from industrial furnaces, which can safely treat even flammable odorous gases and can exhaust the gas at a safe temperature. Another object of the present invention is to provide a deodorization control method for deodorizing exhaust gas containing odorous gases discharged from industrial furnaces, which can safely treat the exhaust gas even if it contains flammable odorous gases, and can exhaust the exhaust gas at a safe temperature. [Means for solving the problem]

[0006] A deodorization control system according to one aspect of the present invention comprises a dilution section having a dilution damper that takes in dilution gas for diluting exhaust gas containing odorous gases discharged from an industrial furnace, and passing the exhaust gas while diluting it with the dilution gas taken in from the dilution damper; a first temperature sensor that detects the temperature of the exhaust gas passing through the dilution section; an oxidation treatment section that heats the exhaust gas containing odorous gases with a burner to subject the odorous gas to high-temperature oxidation treatment; an exhaust section that directs the exhaust gas flowing out from the oxidation treatment section to the outside; a second temperature sensor that detects the temperature of the exhaust gas in the exhaust section; a heat exchanger in the exhaust section that recovers heat from the exhaust gas; and a control section that controls at least the dilution section, the dilution damper, the first temperature sensor, and the second temperature sensor, and the control section controls the dilution damper so that the odorous gas concentration is below the lower explosion limit based on the odorous gas concentration in the exhaust gas and the temperature of the exhaust gas detected by the first temperature sensor, and controls the exhaust gas to maintain a predetermined temperature range based on the temperature of the exhaust gas detected by the second temperature sensor.

[0007] A deodorization control method according to an embodiment of the present invention includes the steps of detecting the odorous gas concentration and exhaust gas temperature of exhaust gas containing odorous gas discharged from an industrial furnace, diluting the exhaust gas with a dilution gas based on the detected odorous gas concentration and exhaust gas temperature so that the odorous gas concentration is below the lower explosion limit, subjecting the diluted exhaust gas to high-temperature oxidation treatment, detecting the temperature of the exhaust gas after the high-temperature oxidation treatment, and adjusting the exhaust gas to a predetermined temperature range based on the detected temperature of the exhaust gas after the high-temperature oxidation treatment and discharging it to the outside. [Effects of the Invention]

[0008] According to the present invention, a deodorization control system can be provided that deodorizes exhaust gas containing odorous gases discharged from industrial furnaces, and can safely treat the gas even if it contains flammable odorous gases, and can exhaust the gas at a safe temperature. Furthermore, according to the present invention, a deodorization control method can be provided for deodorizing exhaust gas containing odorous gases discharged from industrial furnaces, which can safely treat the exhaust gas even if it contains flammable odorous gases, and can exhaust the exhaust gas at a safe temperature. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing a control system of the deodorization control system of the present embodiment. [Figure 2] 1 is a side view schematically showing a deodorizing device to which the deodorizing control system of the present embodiment can be applied. [Figure 3] FIG. 2 is a diagram showing a flow chart of the deodorization control system of the present embodiment. [Figure 4] 10 is a flowchart of a process from detecting the concentration of odorous gas in exhaust gas to controlling a dilution damper in a dilution unit. [Figure 5] 4 is a flowchart of a process from detecting the temperature of exhaust gas to controlling a heat exchanger in an exhaust unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] The deodorizing control system and deodorizing control method according to this embodiment will be described in detail below with reference to the drawings. This embodiment is not limited to the following description. In addition, some or all of the components in this embodiment can be combined as appropriate. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0011] <Deodorization control system> The deodorization control system of this embodiment has a dilution damper that takes in dilution gas for diluting odorous gas-containing exhaust gas discharged from an industrial furnace, and a dilution section that passes the exhaust gas while diluting it with the dilution gas taken in through the dilution damper. It also has a first temperature sensor that detects the temperature of the exhaust gas passing through the dilution section. It also has an oxidation treatment section that heats the odorous gas-containing exhaust gas with a burner to subject the odorous gas to high-temperature oxidation treatment. It also has an exhaust section that directs the exhaust gas flowing out from the oxidation treatment section to the outside. It also has a second temperature sensor that detects the temperature of the exhaust gas in the exhaust section. It also has a control section that controls at least the dilution section, the dilution damper, the first temperature sensor, and the second temperature sensor. The control section controls the dilution damper based on the odorous gas concentration in the exhaust gas and the exhaust gas temperature detected by the first temperature sensor so that the odorous gas concentration is below the lower explosion limit, and controls the exhaust gas to maintain a predetermined temperature range based on the exhaust gas temperature detected by the second temperature sensor.

[0012] FIG. 1 shows a block diagram of a deodorization control system according to this embodiment. The deodorizing device 10 shown in FIG. 1 includes a dilution unit 12, an oxidation treatment unit 18, an exhaust unit 20, and a control unit 30 electrically connected thereto. The dilution unit 12 includes a concentration sensor 14, a temperature sensor (first temperature sensor) 15, and a dilution damper 16, all of which are electrically connected to the control unit 30. The control unit 30 can acquire information about the concentration of odorous gases in the exhaust gas detected by the concentration sensor 14 and control the dilution damper 16 based on the concentration information. The control unit 30 can also acquire information about the temperature of the exhaust gas (i.e., the odorous gas temperature) detected by the temperature sensor 15. The control unit 30 uses Le Chatelier's law to determine whether the odorous gas concentration is equal to or greater than the lower explosion limit. The odorous gas temperature must also be taken into consideration when estimating the odorous gas concentration at the lower explosion limit based on Le Chatelier's law. Therefore, temperature detection is required in the dilution unit 12. The concentration sensor 14 detects the odorous gas concentration in the exhaust gas, the temperature sensor 15 detects the odorous gas temperature, and if the odorous gas concentration detected while taking the odorous gas temperature into consideration is equal to or higher than the lower explosion limit, the control unit 30 controls the dilution gas flowing in from the dilution damper 16 to make it below the lower explosion limit. It is also possible to measure the flow rate and temperature of the exhaust gas and control the dilution damper 16 to obtain a desired exhaust gas amount. The oxidation treatment unit 18 heats the exhaust gas with a burner and performs high-temperature oxidation treatment of odorous gases in the exhaust gas to deodorize it. The control unit 30 controls the heating temperature by controlling the burner air-fuel ratio of the oxidation treatment unit 18. Furthermore, the exhaust unit 20 has a temperature sensor 22 and a heat exchanger 24, each electrically connected to the control unit 30. The control unit 30 can acquire temperature information of the exhaust gas detected by the temperature sensor 22 and control the heat exchanger 24 based on the temperature information. When the temperature sensor 22 detects the temperature of the exhaust gas and the temperature of the exhaust gas is equal to or higher than a predetermined temperature, the control unit 30 controls the heat exchanger 24 to maintain the temperature below the predetermined temperature and equal to or higher than the acid dew point temperature. For safety reasons, it is preferable to provide a temperature sensor for warning in addition to the control temperature sensor 22. As a result of the above control, the exhaust gas discharged from the industrial furnace flows into the dilution section 12 and is diluted with dilution gas. The diluted exhaust gas is heated by a burner in the oxidation treatment section 18, and odorous gases in the exhaust gas are oxidized and deodorized. The exhaust gas then flows into the exhaust section 20, where it is adjusted by the heat exchanger 24 to be within a predetermined temperature range and then exhausted to the outside. The control section 30 controls the oxidation treatment section 18 to a predetermined heating temperature and heating time to treat the odorous gases in the exhaust gas. With the above configuration, by controlling the deodorization of exhaust gas containing odorous gases discharged from industrial furnaces, even if the exhaust gas contains flammable odorous gases, it can be safely treated and exhausted at a safe temperature. Hereinafter, each component of the deodorizing control system of this embodiment will be described.

[0013] [Dilution part] The dilution unit has a dilution damper that takes in dilution gas to dilute the odorous gas-containing exhaust gas discharged from the industrial furnace, a sensor that detects the concentration of the odorous gas in the exhaust gas, and a temperature sensor (first temperature sensor) that detects the temperature of the exhaust gas passing through the dilution unit.The exhaust gas is diluted with the dilution gas taken in from the dilution damper as it passes through the dilution unit.At this time, the concentration of the odorous gas is detected by the concentration sensor and the temperature is detected by the temperature sensor, and the amount of dilution gas flowing in from the dilution damper is controlled so that the odorous gas concentration is below the lower explosion limit, taking into account the odorous gas temperature.The lower explosion limit varies depending on the odorous gas contained in the exhaust gas, so it is set according to the exhaust gas to be deodorized. The shape of the dilution section may be a pipe or a drum (a square pipe, a rectangular pipe, a flat elliptical pipe, an elliptical pipe, a semicircular pipe, a round pipe, a convex pipe, a trapezoidal pipe, a double trapezoidal pipe, a diamond pipe, a pentagonal pipe, a hexagonal pipe, an octagonal pipe, a polygonal pipe, etc.), and a pipe or drum shape is preferred.

[0014] (concentration sensor) The concentration sensor detects the concentration of odorous gas in the exhaust gas passing through the dilution section. A sensor capable of electrically detecting odorous gases with a concentration of 0 to 60,000 ppm is used as the concentration sensor. To effectively perform its function, the concentration sensor is preferably provided downstream of the dilution damper, on the oxidation treatment section side of the dilution section. Note that the concentration of odorous gas does not necessarily have to be detected by the concentration sensor; if applicable, the concentration may be determined by actual measurement using exhaust gas samples, experiments, simulations, calculations, or the like, and the dilution damper may be controlled based on the concentration.

[0015] Examples of odorous gases include ammonia, methyl mercaptan, hydrogen sulfide, methyl sulfide, methyl disulfide, trimethylamine, acetaldehyde, propionaldehyde, normal butyraldehyde, isobutyraldehyde, normal valeraldehyde, isovaleraldehyde, isobutanol, ethyl acetate, methyl isobutyl ketone, toluene, styrene, xylene, propionic acid, normal butyric acid, normal valeric acid, and isovaleric acid.

[0016] (Temperature sensor (first temperature sensor)) The temperature sensor detects the temperature of the exhaust gas in the dilution section. The temperature sensor is installed, for example, at the inlet of the dilution section, and the detected temperature is used to estimate the odorous gas concentration at the lower explosion limit based on Le Chatelier's law. The temperature sensor may be any sensor that converts the temperature into a physical quantity such as voltage or resistance value and outputs it as an electrical signal.

[0017] (Dilution damper) The dilution damper has the function of introducing dilution gas for diluting the exhaust gas. More specifically, the opening of the dilution damper is adjustable, and the amount of dilution gas that flows in is adjusted according to the opening. The dilution damper is electrically connected to a control unit, and the amount of dilution gas introduced through the dilution damper is controlled by the control unit adjusting the opening of the dilution damper. Examples of dilution gases include air and inert gases (nitrogen, argon, carbon dioxide, etc.). In order to sufficiently dilute the exhaust gas with the dilution gas, the dilution damper is preferably provided on the exhaust gas inlet side of the dilution unit.

[0018] [Oxidation processing section] The oxidation treatment section has a burner, and heats the exhaust gas with the burner to subject odorous gases in the exhaust gas to high-temperature oxidation treatment. The odorous gases in the exhaust gas are deodorized by decomposition through high-temperature oxidation treatment. Because the conditions for the high-temperature oxidation treatment vary depending on the odorous gas, they are determined in advance by analyzing the components of the exhaust gas discharged from the industrial furnace and determining the conditions according to the odorous gases contained therein. That is, the heating temperature and heating time using the burner are determined in advance so that the odorous gases are sufficiently decomposed in the oxidation treatment section. The heating time can also be referred to as the residence time of the exhaust gas in the oxidation treatment section. The heating temperature and heating time in the oxidation treatment section can be determined taking into consideration the following factors: Like the dilution section, the oxidation treatment section can have a pipe or drum shape (square rectangular pipe, rectangular rectangular pipe, flattened elliptical pipe, elliptical pipe, semicircular pipe, round-top pipe, convex-top pipe, trapezoidal pipe, double-trapezoidal pipe, diamond-shaped pipe, pentagonal pipe, hexagonal pipe, octagonal pipe, polygonal pipe, etc.), and a pipe or drum shape is preferred.

[0019] (1) Identification of the properties of the volatile organic gases (odor gases) to be treated The composition of the exhaust gas is analyzed to determine the volatile organic gases (odor gases) to be treated. For example, the molecular composition of the exhaust gas is analyzed online or offline using a highly sensitive, molecularly selective, and responsive electronic trace substance sensor, such as a graphene gas sensor, or a gas chromatograph, and the calorific value corresponding to the concentration of each molecule (concentration of sulfur content) is calculated. (2) Setting the amount of dilution based on the lower explosion limit The amount of dilution is determined based on the lower explosion limit (Le Chatelier's law) and the amount of exhaust gas to be treated is determined based on the temperature of the treated gas. At that time, the temperature dependency is taken into account when estimating the concentration based on Le Chatelier's law. (3) Setting the heating temperature and heating time (retention time) The heating temperature is determined according to the volatile organic gas to be treated, and the heating time (residence time) is also determined. (4) High-temperature combustion method and fuel type setting To achieve the above heating temperature, the burner fuel is determined as follows: heavy oil (A heavy oil / recycled heavy oil), city gas (13A / 6A), and sulfur content. Domestically available heavy oils include A heavy oil, B heavy oil, C heavy oil, recycled heavy oil, and biofuel. Gases include city gas 13A / 12A / 6A / L1 (6B, 6C, 7C) / L2 (5A, 5B, 5AN) / L3 (4A, 4B, 4C) and liquefied petroleum gas (LPG). Other fuels include hydrogen, carbon monoxide, ammonia, dimethyl ether, and others. (5) Determining the amount of combustion exhaust gas required for high-temperature oxidation treatment The volatile organic gas to be treated and the amount of exhaust gas generated when the fuel is burned are set. (6) Setting the required treatment volume for each stage of the chimney effect deodorization system and the required average temperature for the entire system When the flow of exhaust gas from the dilution section through the oxidation treatment section to the exhaust section is caused by the stack effect, the flow rate of the gas to be treated on the dilution side and the flow rate of the combustion exhaust gas side are set. The stack effect will be described later. (7) Setting of the flow control system for the gas to be treated (FIC (Flow Identify Control)) Based on the determined dilution amount of the gas to be treated, the treatment flow rate opening is set from the CV value (Valve Flow Coefficient) of the flow rate adjustment valve so that it is equal to or greater than the dilution side flow rate of the gas to be treated. (8) Determine the overall system heat balance The required dilution amount, required processing temperature, required processing time, and average temperature of the entire system are confirmed from the heat balance of the entire system. (9) Check the temperature at the tip of the exhaust Confirm the acid dew point temperature and heat recovery economics.

[0020] Taking the above factors into consideration, it is preferable to heat the exhaust gas in the temperature range of 650 to 800° C. with a burner in the oxidation treatment section while allowing the exhaust gas to remain there for 0.3 to 1.0 seconds.

[0021] [Exhaust section] The exhaust section plays a role in directing the exhaust gas that has completed oxidation treatment in the oxidation treatment section to the outside. The exhaust section is also equipped with a heat exchanger and a temperature sensor. The temperature sensor detects the temperature of the exhaust gas passing through the exhaust section, and the heat exchanger is controlled based on the detected exhaust gas temperature so that the exhaust gas maintains a predetermined temperature range. More specifically, if the temperature of the exhaust gas exceeds a predetermined temperature, the heat exchanger recovers heat from the exhaust gas to lower the temperature before exhausting it to the outside. The predetermined temperature range is an economical temperature for exhausting to the outside, for example, a temperature that will keep the temperature of the exhaust section inner wall above the dew point temperature, which varies depending on the gas components to be treated, the fuel type, and the combustion conditions. The dew point temperature is the temperature at which the SO2 remaining in the exhaust gas is released. X , NO X , CO2, HO, etc. For example, in an environment where the exhaust gas components are SO3:3 ppm and HO:30%, the sulfuric acid condensation temperature is 136 ° C., and in an environment where HCl:300 ppm and HO:30%, the hydrochloric acid condensation temperature is 72 ° C., and it can be set to 72 to 136 ° C. or 136 ° C. or higher from the dew point temperature in an exhaust gas environment due to a common fuel type or combustion. In addition, like the dilution section and oxidation treatment section, the shape of the exhaust section can be a pipe shape, a drum shape (square rectangular pipe, rectangular rectangular pipe, flattened elliptical pipe, elliptical pipe, semicircular pipe, round pipe, convex pipe, one-trapezoidal pipe, double-trapezoidal pipe, diamond pipe, pentagonal pipe, hexagonal pipe, octagonal pipe, polygonal pipe, etc.), and a pipe shape or drum shape is preferable.

[0022] (Temperature sensor (second temperature sensor)) The temperature sensor detects the temperature of the exhaust gas in the exhaust section. The temperature sensor is installed upstream of the heat exchanger, and if the detected temperature is outside a predetermined temperature range, the heat exchanger is controlled to adjust the exhaust gas temperature to within the predetermined range. The temperature sensor may be any device that converts temperature into a physical quantity such as voltage or resistance value and outputs it as an electrical signal.

[0023] (heat exchanger) A heat exchanger is a device that is installed as needed to recover heat from exhaust gas in the exhaust section. The heat exchanger recovers heat from the exhaust gas and prevents high-temperature gas from being discharged into the outside air. The heat recovered by the heat exchanger can be used in a recuperator, regenerative burner, etc., allowing for effective use of the exhaust heat from the exhaust gas. Examples of heat exchangers include shell-and-tube heat exchangers, plate heat exchangers, fin-and-tube heat exchangers, and double-tube heat exchangers.

[0024] In the deodorization control system of this embodiment, the control unit preferably controls the heat exchanger so that the temperature of the exhaust gas in the exhaust unit is equal to or higher than the dew point. In this way, for example, by setting the temperature of the odorous gas immediately after discharge to 72 to 136°C or 136°C or higher, the temperature exceeds the acid dew point, and therefore corrosion of equipment in the exhaust unit can be suppressed.

[0025] In the deodorizing control system of this embodiment, the dilution section, oxidation treatment section, and exhaust section are arranged so that the exhaust gas discharged from the industrial furnace passes through the dilution section, oxidation treatment section, and exhaust section in that order, and are preferably arranged so that the dilution section, oxidation treatment section, and exhaust section are located vertically above each other, or the exhaust section is located vertically above the dilution section, and the oxidation treatment section is located horizontally between the dilution section and the exhaust section. A device such as a blower can be provided to raise the exhaust gas so that the exhaust gas passes through the dilution section, oxidation treatment section, and exhaust section in that order. On the other hand, by positioning the exhaust section at least vertically above the dilution section, a chimney effect is created, and the exhaust gas can be made to rise through the dilution section, oxidation treatment section, and exhaust section without the need to install equipment such as a blower to raise the exhaust gas.

[0026] [Control Unit] The control unit controls at least the dilution damper, concentration sensor, and temperature sensor of the dilution unit, the oxidation treatment unit, and the heat exchanger and temperature sensor of the exhaust unit.The control unit controls the dilution damper based on the odorous gas concentration in the exhaust gas (e.g., the odorous gas concentration detected by the concentration sensor) and the exhaust gas temperature detected by the temperature sensor so that the odorous gas concentration is below the lower explosion limit.In addition, based on the exhaust gas temperature detected by the temperature sensor, the control unit controls, for example, the heat exchanger so that the exhaust gas maintains a predetermined temperature range. In other words, safety can be ensured by controlling the dilution damper so that the odorous gas concentration is below the lower explosion limit. Also, by recovering the heat of the exhaust gas using a heat exchanger, the exhaust gas can be discharged at a safe temperature. In addition, the recovered heat can be used effectively.

[0027] The control unit may, for example, include a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a storage device. The RAM is used as a working area for the CPU. The CPU executes a program stored in the storage device on the RAM, thereby performing the above control.

[0028] Next, an example of a deodorizing apparatus to which the deodorizing control system of this embodiment is applied is shown in FIG. 2. The deodorizing apparatus 40 shown in FIG. 2 includes a dilution section 42, an oxidation treatment section 46, and an exhaust section 50. The dilution section 42, the oxidation treatment section 46, and the exhaust section 50 are all pipe-shaped. An industrial furnace (not shown) is located below the dilution section 42, and exhaust gas discharged from the industrial furnace is drawn into the dilution section 42. The dilution section 42 has a dilution damper 44 that takes in dilution gas and serves to pass the exhaust gas while diluting it with the dilution gas. The oxidation treatment section 46 also has a burner 48 that heats its interior and serves to pass the exhaust gas while heating it with the burner 48. Furthermore, the exhaust section 50 serves to pass the exhaust gas heated by the burner 48 inside the oxidation treatment section 46 and exhaust it to the outside. In addition, the exhaust section 50 has a heat exchanger 52 that recovers heat from the exhaust gas. The dilution section 42, the oxidation treatment section 46, and the exhaust section 50 are connected so that the exhaust gas discharged from the industrial furnace passes upward (in the X direction in FIG. 2) through the dilution section 42, the oxidation treatment section 46, and the exhaust section 50 in that order. Therefore, the exhaust gas that flows into the dilution section 42 rises due to the stack effect, and is finally exhausted from the outlet of the exhaust section 50. The deodorizing device shown in Figure 2 above is applied with the deodorizing control system of this embodiment, so at least the dilution section 42 and the exhaust section 50 are controlled as described above, and the odorous gas concentration in the exhaust gas is adjusted, as well as the temperature of the exhaust gas discharged to the outside.

[0029] 2 shows a configuration in which the oxidation treatment unit 46 is inclined at an inclination angle α with respect to the horizontal direction. By inclining the oxidation treatment unit 46 at the inclination angle α with respect to the horizontal direction, the vertically upward component of the buoyancy force acting on the exhaust gas due to the chimney effect is reduced, and the upward rising speed of the exhaust gas is slower compared to the exhaust gas rising vertically upward. As a result, the residence time of the exhaust gas in the oxidation treatment unit 46 is longer. The inclination angle α is preferably 0 to 90° with respect to the horizontal direction. When the inclination angle is 0°, the exhaust unit 50 is located vertically above the dilution unit 42, and the oxidation treatment unit 46 is installed horizontally between the dilution unit 42 and the exhaust unit 50.

[0030] Next, an example of a flow sheet of the deodorization control system of this embodiment will be described with reference to Fig. 3. Fig. 3 shows the flow of exhaust gas in the deodorizing device 40 shown in Fig. 2, and on the right side of the deodorizing device 40, a graph is shown of the temperature and flow rate of the exhaust gas corresponding to each position in the deodorizing device 40. As the deodorizing device 40 has been described above in the explanation of Fig. 2, the same components are assigned the same reference numerals and explanations thereof will be omitted. In Figure 3, GA (Gas Analyzer) indicates a gas analyzer concentration meter, TI (Temperature Indication) indicates a temperature display unit, TIC (Temperature Indication Control) indicates a temperature display control unit, FI (Flow Indication) indicates a flow rate display unit, FIC (Flow Identify Control) indicates a flow rate adjustment unit, PI (Pressure Indication) indicates a pressure display unit, and VC (Valve Control) indicates a valve control unit.

[0031] The flow of treating exhaust gas in Fig. 3 will be described. First, for exhaust gas containing odorous gas discharged from an industrial furnace, the dilution amount is calculated based on the odorous gas concentration in the exhaust gas detected by a concentration sensor and the exhaust gas temperature detected by a temperature sensor so that the odorous gas concentration will be below the lower explosion limit. Then, in dilution unit 42, the VC of the dilution damper is controlled so that the dilution amount is achieved.

[0032] In the oxidation treatment unit 46, the combustion output of the VC and burner 48 is controlled so that, for example, the oxidation treatment temperature is 750°C and the residence time is 1 second. More specifically, the control motor 62 controls the fuel in the fuel tank 64 and the air supplied from the air supplier 63, thereby controlling the combustion output.

[0033] In the exhaust unit 50, the coolant is circulated in the heat exchanger 52 to recover exhaust heat so that the outlet temperature is, for example, 72 to 136°C or 136°C or higher.

[0034] The graphs on the right side of the deodorizing device 40 in Fig. 3 will be explained. In the graphs in Fig. 3, the graphs marked with "◇" indicate changes in exhaust gas temperature, and the graphs marked with "◯" indicate changes in exhaust gas flow rate. In addition, in the graphs in Fig. 3, the horizontal axis (the axis extending from the front of the page to the back) indicates the height of each position in the deodorizing device 40 when the overall height is 100%, and the vertical axis indicates the exhaust gas temperature for the graphs marked with "◇" and the exhaust gas flow rate for the graphs marked with "◯". Here, the temperature is shown relative to the maximum temperature when it is 100%. Similarly, the smoke volume is shown relative to the flow rate when the maximum flow rate is 100%. As shown in the graph of Figure 3, the exhaust gas passes through the dilution section 42 at a temperature that is 10% of the maximum temperature (above atmospheric temperature and above the dew point temperature of the exhaust gas). Next, the exhaust gas is heated by the burner 48 near the inlet of the oxidation treatment section 46 to the maximum temperature (100%), and as it proceeds through the oxidation treatment section 46, its temperature decreases and it flows into the exhaust section 50. Thereafter, its temperature decreases slightly in the exhaust section 50, and it further decreases as it passes through the heat exchanger 52 before being exhausted to the outside. Meanwhile, the flow rate of the exhaust gas passes through the dilution section 42 at a constant flow rate, but in the oxidation treatment section 46, the flow rate increases near the inlet due to the combustion exhaust gas from the burner 48, and then it passes through the exhaust section 50 at a constant flow rate and is exhausted to the outside. The deodorization control system of this embodiment is controlled according to the above flow, but this embodiment is not limited to the above flow.

[0035] <Deodorization control method> The deodorization control method of this embodiment includes a step (hereinafter also referred to as "step A") of detecting the odor gas concentration of odorous gas-containing exhaust gas discharged from an industrial furnace and detecting the exhaust gas temperature. It also includes a step (hereinafter also referred to as "step B") of diluting the exhaust gas with a dilution gas based on the detected odor gas concentration and the detected exhaust gas temperature so that the odor gas concentration is below the lower explosion limit. It further includes a step (hereinafter also referred to as "step C") of subjecting the diluted exhaust gas to high-temperature oxidation treatment. It also includes a step (hereinafter also referred to as "step D") of detecting the temperature of the exhaust gas after the high-temperature oxidation treatment. It also includes a step (hereinafter also referred to as "step E") of adjusting the exhaust gas to a predetermined temperature range based on the detected temperature of the exhaust gas after the high-temperature oxidation treatment and discharging it to the outside.

[0036] The deodorization control method of this embodiment is a control method that can be applied to, for example, the deodorization control system of this embodiment as described above. Each step will be explained below. When the deodorization control method of this embodiment is applied to the deodorization control system of this embodiment, the following processing can be executed by the control unit.

[0037] [Step A] In step A, the odorous gas concentration of the exhaust gas containing the odorous gas discharged from the industrial furnace and the exhaust gas temperature are detected. That is, as described in the deodorization control system of this embodiment, the concentration sensor detects the odorous gas concentration in the exhaust gas and the exhaust gas temperature.

[0038] [Step B] In step B, the exhaust gas is diluted with dilution gas based on the detected odorous gas concentration and the detected exhaust gas temperature so that the odorous gas concentration is below the lower explosion limit. That is, if the odorous gas concentration detected in step A is equal to or greater than the lower explosion limit, the dilution damper is controlled to dilute the exhaust gas with dilution gas. Note that if the odorous gas concentration is already below the lower explosion limit, control of the dilution damper is not necessary. Furthermore, excessive dilution of the exhaust gas 1) increases the amount of odorous gas to be treated, 2) lowers the temperature of the odorous gas to be treated, which leads to 3) an increase in the amount of fuel used to reach the high-temperature oxidation treatment control temperature, and 4) an increase in the amount of combustion exhaust gas due to the increased fuel consumption. Therefore, it is preferable to dilute the exhaust gas to the minimum necessary. However, since the concentration sensors and temperature sensors for the gas to be treated may have some measurement errors depending on their characteristics and resolution, a safety factor must be considered.

[0039] [Step C] In step C, the diluted exhaust gas is subjected to high-temperature oxidation treatment. As explained in the deodorization control system of this embodiment, odorous gases in the exhaust gas are heated to a predetermined heating temperature and heating time for oxidation treatment. Then, in step C, the odorous gases are decomposed and deodorized.

[0040] [Step D] In step D, the temperature of the exhaust gas after the high-temperature oxidation treatment is detected. Although the exhaust gas after the high-temperature oxidation treatment in step C is deodorized, the temperature may be too high if left as is. In particular, if the exhaust gas is discharged to the outside at a high temperature, a large amount of thermal energy will be released to the outside, resulting in a large energy loss. Therefore, it is preferable to detect the temperature of the exhaust gas at the exhaust flue outlet after the high-temperature oxidation treatment, and if the temperature is high, to recover heat from the exhaust gas using, for example, a heat exchanger and make effective use of the recovered heat. Therefore, in step D, the temperature of the exhaust gas after the high-temperature oxidation treatment is detected in preparation for the following step E.

[0041] [Step E] In step E, based on the temperature detected in step D, heat is recovered from the exhaust gas using, for example, a heat exchanger, and the exhaust gas is brought to a predetermined temperature range and then discharged to the outside. That is, if the temperature detected in step D is equal to or higher than the predetermined temperature, heat is recovered from the exhaust gas using a heat exchanger or the like to lower the temperature before being discharged to the outside. If the temperature of the exhaust gas is already below the predetermined temperature, there is no need to control the heat exchanger or the like.

[0042] FIG. 4 shows a flowchart of an example of the processing procedure performed in the dilution unit 12. This processing is performed by the control unit 30 and starts when exhaust gas from the industrial furnace flows into the dilution unit 12. First, the concentration sensor 14 of the dilution unit 12 measures the odorous gas concentration in the exhaust gas (step SA1). In addition, the temperature sensor 15 measures the temperature of the exhaust gas (step SA2). Next, it is determined whether the measured odorous gas concentration is equal to or greater than the lower explosion limit, taking into account the measured temperature (step SA3). If the odorous gas concentration is equal to or greater than the lower explosion limit (YES), the dilution damper is controlled so that the odorous gas concentration is below the lower explosion limit (step SA4). Thereafter, it is determined whether the odorous gas concentration is below the lower explosion limit (step SA5). If the odorous gas concentration is below the lower explosion limit (YES), the processing ends. If the odorous gas concentration is not below the lower explosion limit (NO), the processing returns to step SA1, and the dilution damper is controlled so that the odorous gas concentration is below the lower explosion limit. Steps SA1 to SA4 are repeated until the odorous gas concentration becomes below the lower explosion limit. On the other hand, if the odorous gas concentration is less than the lower explosion limit (NO) in step SA3, the process ends.

[0043] FIG. 5 shows a flowchart of an example of the processing procedure performed in the exhaust unit 20. This processing is performed by the control unit 30 and is initiated when exhaust gas from the industrial furnace flows into the exhaust unit 20. First, the temperature sensor 22 in the exhaust unit 20 detects the temperature of the exhaust gas (step SB1). Next, it is determined whether the detected temperature of the exhaust gas is equal to or higher than a specified temperature (step SB2). If the temperature of the exhaust gas is equal to or higher than the specified temperature (YES), the heat exchanger 24 is controlled so that the temperature is below the specified temperature (step SB3). Then, it is determined whether the temperature of the exhaust gas is below the specified temperature (step SB4). If the temperature of the exhaust gas is below the specified temperature (YES), the processing ends. If the temperature of the exhaust gas is not below the specified temperature (NO), the processing returns to step SB1, and the heat exchanger 24 is controlled so that the temperature is below the specified temperature. Steps SB1 to SB4 are repeated until the temperature of the exhaust gas becomes below the specified temperature. On the other hand, if the temperature of the exhaust gas is below the specified range (NO) in step SB2, the process ends.

[0044] As described above, the deodorization control method of this embodiment can safely treat even flammable odorous gases and can exhaust the gas at an economical temperature. In other words, by controlling the exhaust gas temperature to be at least equal to or higher than the acid dew point, it is possible to protect the equipment from a corrosive environment and to expect a contribution to economic efficiency by recovering heat up to the acid dew point. [Explanation of symbols]

[0045] 10 Deodorizing device 12 42 Dilution section 14 Concentration sensor 15 Temperature sensor (first temperature sensor) 16 44 Dilution damper 18 46 Oxidation treatment section 20 50 Exhaust section 22 Temperature sensor (second temperature sensor) 24 52 Heat exchanger 30 Control Unit 40 Deodorizing device

Claims

1. a dilution section having a dilution damper that takes in dilution gas for diluting exhaust gas containing odorous gas discharged from an industrial furnace, and that passes the exhaust gas while diluting it with the dilution gas taken in from the dilution damper; a first temperature sensor that detects the temperature of the exhaust gas passing through the dilution section; an oxidation treatment unit that heats the exhaust gas containing the odorous gas with a burner to perform high-temperature oxidation treatment on the odorous gas; an exhaust unit that guides the exhaust gas flowing out from the oxidation treatment unit to the outside; a second temperature sensor that detects the temperature of the exhaust gas in the exhaust section; a control unit that controls at least the dilution unit, the dilution damper, the first temperature sensor, and the second temperature sensor, The control unit controls the dilution damper based on the odorous gas concentration in the exhaust gas and the temperature of the exhaust gas detected by the first temperature sensor so that the odorous gas concentration is below the lower explosion limit, and controls the exhaust gas based on the temperature of the exhaust gas detected by the second temperature sensor so that the exhaust gas maintains a predetermined temperature range.

2. The dilution unit further includes a concentration sensor for detecting the concentration of odorous gas in the exhaust gas passing through the dilution unit, The control unit controls the concentration sensor together with the dilution unit, the dilution damper, the first temperature sensor, and the second temperature sensor, and controls the dilution damper based on the odorous gas concentration in the exhaust gas detected by the concentration sensor so that the odorous gas concentration is below the lower explosion limit.

3. The exhaust unit further includes a heat exchanger that recovers heat from the exhaust gas, The control unit controls the heat exchanger together with the dilution unit, the dilution damper, the first temperature sensor, and the second temperature sensor, and controls the dilution damper based on the odorous gas concentration in the exhaust gas so that the odorous gas concentration is below the lower explosion limit.

4. 3. The deodorizing control system according to claim 1, wherein the dilution section, the oxidation treatment section, and the exhaust section are arranged so that exhaust gas discharged from the industrial furnace passes through the dilution section, the oxidation treatment section, and the exhaust section in sequence, and the dilution section, the oxidation treatment section, and the exhaust section are arranged so that they are positioned vertically above each other, or the exhaust section is positioned vertically above the dilution section, and the oxidation treatment section is arranged horizontally between the dilution section and the exhaust section.

5. 3. The deodorization control system according to claim 2, wherein the dilution damper is provided on an inlet side of the dilution section for exhaust gas, and the concentration sensor is provided on an exhaust outlet side of the dilution section.

6. 3. The deodorization control system according to claim 1, wherein the exhaust gas is heated in the oxidation treatment unit by the burner to a temperature range of 650 to 800° C. and allowed to stay there for 0.3 to 1.0 seconds.

7. The deodorization control system according to claim 3 , wherein the control unit controls the heat exchanger so that the temperature of the exhaust gas in the exhaust unit is equal to or higher than a dew point temperature.

8. A step of detecting an odorous gas concentration of exhaust gas containing odorous gas discharged from an industrial furnace and detecting the exhaust gas temperature; diluting the exhaust gas with a dilution gas based on the detected odorous gas concentration and the detected exhaust gas temperature so that the odorous gas concentration is less than the lower explosion limit; a step of subjecting the diluted exhaust gas to high-temperature oxidation treatment; Detecting the temperature of the exhaust gas after the high-temperature oxidation treatment; a step of adjusting the exhaust gas to a predetermined temperature range based on the detected temperature of the exhaust gas after the high-temperature oxidation treatment and discharging the exhaust gas to the outside; A method for controlling deodorization, comprising:

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