A system and method for treating tail gas from an isophthalonitrile process

Abstract

The invention provides an isophthalonitrile process tail gas treatment system and treatment method. The treatment system comprises a process tail gas collection unit, a process tail gas mixing unit, an emergency treatment unit, an RTO unit, a tail gas denitrification unit, a tail gas cooling unit and a tail gas emission unit; the process tail gas collection unit, the process tail gas mixing unit, the RTO unit, the tail gas denitrification unit, the tail gas cooling unit and the tail gas emission unit are connected in sequence; the process tail gas collection unit is also directly connected to the tail gas emission unit through the emergency treatment unit; the treatment system has high safety performance, high treatment efficiency, low nitrogen oxide generation, and effectively utilizes waste heat in the tail gas, can effectively reduce enterprise treatment costs, optimize on-site working environment, has a high pollutant removal rate, and has a positive effect on environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of pollutant treatment, and relates to a system and method for treating ammonia-containing tail gas, and in particular to a system and method for treating tail gas from an isophthalonitrile process. Background Art

[0002] The raw materials for synthesizing isophthalonitrile are meta-xylene, ammonia, and air, which undergo an ammoxidation reaction in a fluidized bed. This reaction requires an ammonia excess of approximately 50%. The process's tail gas contains approximately 4% ammonia by volume, while other VOCs account for approximately 1%. Existing methods for treating isophthalonitrile tail gas primarily include absorption, condensation, adsorption, and incineration.

[0003] The absorption method mainly uses water or acidic solution (hydrochloric acid or sulfuric acid) to fully contact the treated waste gas to convert it into ammonia water, ammonium chloride or ammonium sulfate. Due to the limitations of ammonia water usage, most companies use dilute sulfuric acid solution absorption method and separate ammonium sulfate crystals through evaporation concentration and cooling crystallization as raw materials for compound fertilizer production, so as to achieve comprehensive utilization.

[0004] The condensation method is to use a heat exchanger to condense and cool the tail gas containing organic waste gas in the production process, so that the organic vapor condenses into liquid to achieve the purpose of gas separation. Then, the ammonia in the waste gas is condensed into liquid ammonia through compression and condensation. The liquid ammonia is separated through a gas-liquid separator. The ammonia recovery rate of this method is over 90%. Since the process of ammoxidation of meta-xylene to isophthalonitrile uses air as the oxygen source, the general air consumption is 10 to 14 times the ammonia consumption. After the reaction, the excess ammonia is discharged with a large amount of nitrogen, carbon dioxide and other gases. Obviously, the high energy consumption of using the condensation method to recover ammonia is undoubtedly unacceptable.

[0005] The adsorption method is a process in which various pollutants in the exhaust gas are adsorbed on its surface by an adsorbent in order to separate them from the main body. However, the adsorption method currently faces the problem of adsorbent recovery and further treatment. Therefore, the application of the adsorption method to the treatment of isophthalonitrile exhaust gas needs to be studied and developed.

[0006] The regenerator incineration method is a high-temperature pyrolysis treatment technology. The organic waste to be treated undergoes an oxidative combustion reaction in the regenerator. The harmful substances in the exhaust gas are oxidized and pyrolyzed at a high temperature of 760-1100°C and destroyed. The heat of the high-temperature gas is stored in the regenerator, and the next exhaust gas is preheated before entering the combustion chamber for oxidative pyrolysis. It is a treatment technology that can save fuel while achieving harmlessness of waste. The process has high heat exchange efficiency, low operating costs and a high degree of automation. However, the ammonia content in the exhaust gas of the isophthalonitrile process is high and the exhaust gas has a high calorific value. If not controlled, it is easy to make the temperature difficult to control. The nitrogen oxides produced by the combustion of ammonia are high, and even cause great safety risks.

[0007] CN101491747A1 discloses a method for treating waste gas from the production of isophthalonitrile, comprising the following steps: (1) waste gas from the isophthalonitrile production line first enters a pre-treatment unit to remove impurities therein; (2) enters a heat exchanger; (3) enters a catalytic combustion furnace for low-temperature catalytic combustion, where hydrogen cyanide is selectively oxidized by the catalyst into non-toxic nitrogen, carbon dioxide, and water, while ammonia is retained; (4) the decyanated waste gas enters a heat exchanger to preheat the waste gas to be treated and is cooled; (5) enters a water cooler to cool to room temperature, and the cooled decyanated ammonia-containing waste gas is introduced into an ammonia absorption tower, where ammonia is absorbed by sulfuric acid solution sprayed from the top and is recovered as ammonium sulfate, thereby completing the treatment of waste gas from the production of isophthalonitrile. This method mainly uses an absorption method to treat tail gas containing ammonia, which has low treatment efficiency and high cost.

[0008] Therefore, providing an isophthalonitrile process tail gas treatment system and treatment method with high safety performance, high treatment efficiency, low nitrogen oxide generation, and good nitrogen oxide removal effect is of great significance for improving the isophthalonitrile process waste gas treatment effect, reducing the enterprise's treatment costs, optimizing the on-site working environment, and improving the enterprise's economic benefits. Summary of the Invention

[0009] In response to the problems existing in the prior art, the present invention aims to provide an isophthalonitrile process tail gas treatment system and treatment method. The treatment system can collect and premix waste gases from multiple production processes and then centrally treat them. In addition, an emergency treatment unit is designed to ensure safety during operation. The treatment system has low energy consumption, a high pollutant removal rate, and a positive effect on environmental protection.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides an isophthalonitrile process tail gas treatment system, the treatment system comprising a process tail gas collection unit, a process tail gas mixing unit, an emergency treatment unit, an RTO unit, a tail gas denitrification unit, a tail gas cooling unit, and a tail gas discharge unit;

[0012] The process tail gas collection unit, the process tail gas mixing unit, the RTO unit, the tail gas denitrification unit, the tail gas cooling unit and the tail gas emission unit are connected in sequence;

[0013] The process tail gas collection unit is also directly connected to the tail gas emission unit through the emergency treatment unit.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] As a preferred technical solution of the present invention, the process tail gas collection unit includes a scrubber, a premixer and a flame arrester connected in sequence.

[0016] Preferably, an exhaust gas concentration detector is further provided on the connecting pipeline between the premixer and the fire-retardant equipment.

[0017] Preferably, the fire arresting device comprises a water seal box or a wire mesh flame arrester;

[0018] In the present invention, the provision of the flame arrester equipment can more thoroughly remove impurities such as solid particles in the process tail gas, ensure that the tail gas ends of multiple production units have the same negative pressure, enable smooth production of each isophthalonitrile unit, and at the same time ensure that the process tail gas is evenly mixed, so that the process tail gas detection value is true and valid.

[0019] Preferably, there are no less than one scrubbing tower, such as 1, 2, 3, 4, 5 or 6, etc., but it is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable and are arranged in parallel.

[0020] In the present invention, the treatment system can simultaneously treat isophthalonitrile process tail gas generated by multiple sets of production equipment, and each process tail gas can be subsequently treated by passing through a scrubbing tower.

[0021] Preferably, a spraying device is provided in the scrubbing tower.

[0022] In the present invention, the scrubber is a gas-liquid co-current scrubber from top to bottom. The spraying equipment inside the scrubber is evenly distributed with atomizing nozzles. The evenly distributed atomizing nozzles are dual-fluid nozzles, which can fully remove impurities such as solid particles in the tail gas. The process tail gases generated by multiple sets of production equipment are respectively scrubbed and then enter the premixer from the same direction and angle, and are discharged from the side and bottom; the bottom of the premixer is designed in a funnel shape to collect condensate or solid particles.

[0023] Preferably, the fire-blocking device of the process tail gas collection unit is connected to the process tail gas mixing unit and the emergency treatment unit respectively through a three-way valve.

[0024] As a preferred technical solution of the present invention, the process tail gas mixing unit includes an inlet mixing box.

[0025] Preferably, a tail gas concentration detector is provided on the pipeline between the process tail gas mixing unit and the RTO unit.

[0026] In the present invention, in order to ensure the safe operation of the RTO unit, the treatment system is equipped with an exhaust gas concentration detector on the pipeline between the process exhaust gas mixing unit and the RTO unit. When the exhaust gas concentration is abnormally high, which may have a safety impact on the operation of the RTO unit (such as safety risks such as temperature runaway and explosion), the process exhaust three-way valve is switched to the emergency treatment unit, and the process exhaust is directly treated by activated carbon adsorption and water spray tower in two stages, and then sent to the chimney by the induced draft fan for high-altitude discharge.

[0027] As a preferred technical solution of the present invention, the RTO unit includes a system fan, an RTO furnace and an outlet mixing box connected in sequence.

[0028] Preferably, the inlet mixing box of the process tail gas mixing unit is connected to the system fan of the RTO unit.

[0029] Preferably, the RTO furnace includes a bottom cavity, an air exchange valve, a heat storage chamber, a combustion chamber, a combustion string and a combustion-supporting fan.

[0030] In the present invention, the structure of the RTO furnace is an existing structure and will not be described in detail here.

[0031] Preferably, the system fan and the outlet mixing box are independently connected to the RTO furnace through the bottom cavity.

[0032] Preferably, the air exchange valve of the bottom cavity is a lift valve.

[0033] Preferably, the RTO furnace has no less than 3 regenerators, such as 3, 4, 5 or 6, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, each of the heat storage chambers is independently filled with a heat storage body.

[0035] Preferably, the filling height of the heat storage body is 500-1200 mm, for example, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm or 1200 mm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, saddle ring layers are independently provided at the top and bottom of the heat storage body, and the height of the top saddle ring layer is 100 to 800 mm, for example, 100 mm, 300 mm, 500 mm or 800 mm; the height of the bottom saddle ring layer is 100 to 500 mm, for example, 100 mm, 300 mm, 400 mm or 500 mm. The selection of the above numerical values ​​is not limited to the listed values, and other unlisted values ​​within the respective numerical ranges are also applicable.

[0037] In the present invention, the saddle ring layer is designed so that the tail gas is evenly distributed, and an explosion relief door is provided on the top of the combustion chamber.

[0038] Preferably, adjacent heat storage chambers are connected by arches, and the top of the arch of each heat storage chamber is higher than the heat storage body.

[0039] In the present invention, the regenerators are connected by arches to avoid short-flow of some flue gas, which may result in insufficient residence time. This design allows the exhaust gas to be fully preheated in the regenerator and then fully oxidized and decomposed in the combustion chamber of the RTO furnace, thus avoiding incomplete oxidation due to insufficient residence time of the exhaust gas.

[0040] In the present invention, a back-blowing valve or a back-extraction valve for back-extracting the exhaust gas to the inlet of the system fan is provided at the bottom of each heat storage chamber.

[0041] Preferably, the combustion chamber of the RTO furnace is also independently connected to the tail gas mixing unit and the outlet mixing box through bypass pipelines.

[0042] In the present invention, a distributor is arranged inside the outlet mixing box, the distributor is a basket-type structure, and the distribution holes are evenly arranged.

[0043] As a preferred technical solution of the present invention, the tail gas denitration unit includes an ammonia injection device, a static mixer and a denitration reactor connected in sequence.

[0044] In the present invention, the ammonia in the ammonia spraying equipment comes from the ammonia evaporator in the isophthalonitrile production workshop, or from the gaseous ammonia on the top of the liquid ammonia storage tank in the tank area.

[0045] Preferably, the outlet mixing box of the RTO unit is connected to the static mixer of the tail gas denitrification unit.

[0046] Preferably, the denitration reactor comprises a vertical reactor.

[0047] Preferably, a denitration catalyst is provided in the denitration reactor.

[0048] Preferably, the number of layers of the denitration catalyst is not less than 2, such as 2 layers, 3 layers, 4 layers, 5 layers or 6 layers, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] Preferably, an acoustic pulse dust removal device is provided in each layer of denitration catalyst.

[0050] Preferably, the denitration catalyst is of medium-high temperature type.

[0051] In the present invention, the operating temperature of the high-temperature denitration catalyst is 240-370°C, for example, 240°C, 280°C, 300°C, 320°C, 350°C or 370°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0052] As a preferred technical solution of the present invention, the exhaust gas cooling unit includes an exhaust gas heat exchanger and a water spray cooling tower connected in sequence.

[0053] Preferably, the denitration reactor of the tail gas denitration unit is connected to the tail gas heat exchanger of the tail gas cooling unit.

[0054] Preferably, the tail gas discharge unit includes an induced draft fan and a chimney connected in sequence.

[0055] Preferably, the water spray cooling tower of the tail gas cooling unit is connected to the induced draft fan of the tail gas discharge unit.

[0056] Preferably, the emergency treatment unit includes an adsorption tower and a water spray tower connected in sequence.

[0057] Preferably, the adsorption tower comprises an activated carbon adsorption tower.

[0058] In the present invention, the two-stage arrangement of the activated carbon adsorption tower and the water spray tower can fully adsorb VOCs in the tail gas and absorb ammonia in the tail gas, thereby meeting the environmental protection treatment requirements.

[0059] Preferably, the water spray tower of the emergency treatment unit is connected to the induced draft fan of the tail gas emission unit.

[0060] As a preferred technical solution of the present invention, the treatment system also includes an unorganized exhaust gas collection unit.

[0061] Preferably, the fugitive exhaust gas collection unit includes a fugitive exhaust gas main pipe and a fugitive exhaust gas collection branch pipe directly connected to the fugitive exhaust gas main pipe.

[0062] Preferably, there is at least one branch pipe for collecting unorganized exhaust gas.

[0063] Preferably, the fugitive exhaust gas main pipe of the fugitive exhaust gas collection unit is connected to the inlet mixing box of the process exhaust gas mixing unit through the exhaust gas heat exchanger of the exhaust gas cooling unit.

[0064] In the present invention, the treatment system makes full use of the waste heat of the RTO unit (note: the heat of the entire process system is generated by the RTO unit), uses the tail gas heat exchanger to heat the unorganized exhaust gas, and increases the inlet temperature and bottom temperature of the RTO furnace. After the inlet temperature and bottom temperature of the RTO furnace are increased, the sublimation rate of the residual isophthalonitrile in the tail gas can be increased, ensuring that there is no precipitation and polymerization of isophthalonitrile in the inlet mixing box, the system fan, the bottom cavity and the pipeline of the RTO furnace, and ensuring that the inlet pipeline and the bottom of the RTO furnace are not blocked.

[0065] In a second aspect, the present invention provides a method for treating isophthalonitrile process tail gas, the treatment method being carried out using the treatment system as described in the first aspect, the treatment method comprising the following steps:

[0066] Collect the isophthalonitrile process tail gas, and then carry out combustion, denitrification and cooling in sequence before discharging;

[0067] When abnormal exhaust gas concentration is detected, the collected isophthalonitrile process exhaust gas will be switched to the emergency treatment unit and discharged after emergency treatment.

[0068] As a preferred technical solution of the present invention, the processing method more specifically operates as follows:

[0069] (1) The isophthalonitrile process tail gas is premixed after scrubbing, and the pressure in the main pipe after premixing is controlled to be negative pressure, and then enters the inlet mixing box through the fire-retardant facility and the three-way valve in sequence;

[0070] Collect unorganized exhaust gas, control the pressure in the main pipe to be negative, and then enter the inlet mixing box after heat exchange in the exhaust heat exchanger;

[0071] (2) The two types of exhaust gas in step (1) are mixed and transported to the RTO furnace through the system fan, and then pass through the bottom cavity and the first regenerator from bottom to top to enter the combustion chamber for combustion. The exhaust gas after combustion is divided into three parts, the first part is directly discharged to the outlet mixing box, the second part returns to the inlet mixing box, and the third part passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and then is discharged to the outlet mixing box;

[0072] (3) The tail gas in the outlet mixing box of step (2) and the ammonia in the ammonia spraying equipment enter into a static mixed gas for mixing, and denitrification is performed after mixing;

[0073] (4) The denitrified tail gas is heat exchanged with the unorganized exhaust gas in step (1), and then discharged after being cooled by water spraying;

[0074] When abnormality is detected in the tail gas in the inlet mixing box, the three-way valve is switched to the emergency treatment unit, so that the process tail gas in step (1) is discharged after passing through the adsorption tank and the water spray tower in sequence.

[0075] In the present invention, the treatment method first collects and premixes the process exhaust gases generated by multiple sets of production equipment, and then leads them to the inlet mixing box through a pipeline; at the same time, the unorganized exhaust emissions from various locations on site are transported to the unorganized exhaust emission main pipe through various branch pipes, preheated using the waste heat of the exhaust denitrification unit, and then transported to the inlet mixing box. The fully mixed exhaust gases are sent to the RTO furnace through the system fan for full incineration. The two high-temperature bypasses on the RTO furnace combustion chamber can increase the temperature of the mixed exhaust gas at the RTO furnace inlet on one side, and increase the temperature of the RTO unit outlet mixing box on the other side to ensure the stable operation of the denitrification unit. The denitrified exhaust is cooled by the exhaust heat exchanger and the water spray tower, and then sent to the chimney through the induced draft fan for high-altitude discharge.

[0076] In the present invention, the inlet mixing box is a vertical cylindrical box, the process tail gas enters horizontally from the upper side, and the unorganized exhaust gas enters vertically from the top after preheating; the high-temperature flue gas generated by combustion in the RTO furnace enters vertically from the top.

[0077] In the present invention, the denitration reaction is an SCR denitration reaction.

[0078] As a preferred technical solution of the present invention, the ammonia content in the isophthalonitrile process tail gas in step (1) is 1000-40000 mg / m 3 , for example 1000mg / m 3 , 5000mg / m 3 , 10000mg / m 3 , 15000mg / m 3 , 20000mg / m 3 , 25000mg / m 3 , 30000mg / m 3 , 35000mg / m 3 or 40,000 mg / m 3 etc., but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0079] Preferably, the temperature of the isophthalonitrile process tail gas in step (1) is 30 to 90° C., for example, 30° C., 40° C., 50° C., 60° C., 70° C., 80° C. or 90° C., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0080] Preferably, the air volume of the isophthalonitrile process tail gas in step (1) is 8000 to 50000 Nm 3 / h, for example 8000Nm 3 / h、10000Nm 3 / h、15000Nm 3 / h、20000Nm 3 / h、25000Nm 3 / h、 30000Nm 3 / h、40000Nm 3 / h, 45000Nm3 / h or 50000Nm 3 / h, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0081] Preferably, the ammonia content in the unorganized exhaust gas in step (1) is 0 to 5000 mg / m 3 , for example 0mg / m 3 , 1000mg / m 3 , 2000mg / m 3 3000mg / m 3 4000mg / m 3 or 5000 mg / m 3 etc., but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0082] Preferably, the air volume ratio of the unorganized exhaust gas emitted in step (1) to the isophthalonitrile process exhaust gas is 0 to 10, for example, 0, 3, 5, 7, 9 or 10, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0083] Preferably, the temperature of the process tail gas after scrubbing in step (1) is 20-95°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 85°C or 95°C, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0084] Preferably, in step (1), the pressure in the main pipe after premixing is controlled to be -100 to -2500 Pa, for example, -100 Pa, -300 Pa, -500 Pa, -800 Pa, -1000 Pa, -1300 Pa, -1500 Pa, -1700 Pa, -2000 Pa, -2200 Pa or -2500 Pa, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0085] Preferably, in step (1), the pressure in the collected unorganized exhaust gas main pipe is controlled to be -100 to -2500 Pa, -100 Pa, -300 Pa, -500 Pa, -800 Pa, -1000 Pa, -1300 Pa, for example, -1500 Pa, -1700 Pa, -2000 Pa, -2200 Pa or -2500 Pa, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0086] Preferably, the temperature of the unorganized exhaust gas after heat exchange in step (1) is 150-250°C, for example, 150°C, 170°C, 200°C, 230°C or 250°C, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0087] Preferably, the temperature of the two types of exhaust gases after mixing in step (2) is 130-180°C, for example, 120°C, 150°C, 160°C, 170°C or 180°C, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0088] Preferably, the combustion temperature in step (2) is 780-950°C, such as 780°C, 800°C, 850°C, 900°C or 950°C, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0089] Preferably, during the combustion process in step (2), the residence time of the tail gas is 1 to 3 seconds, such as 1 second, 2 seconds or 3 seconds, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0090] Preferably, the temperature in the outlet mixing box in step (2) is 250-350°C, such as 250°C, 280°C, 300°C, 330°C or 350°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0091] Preferably, the temperature of the denitrified tail gas in step (3) is 250-350°C, such as 250°C, 280°C, 300°C, 330°C or 350°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0092] Preferably, the temperature of the denitrified tail gas after heat exchange in step (4) is 150-250°C, for example, 150°C, 180°C, 200°C, 230°C or 250°C, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0093] Preferably, the temperature of the exhaust gas after water spray cooling in step (4) is 120-180°C, for example, 120°C, 130°C, 150°C, 170°C or 180°C, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0094] Preferably, the tower outlet pressure for water spray cooling in step (4) is -1000 to -3000 Pa, for example, -1000 Pa, -1500 Pa, -2000 Pa, -2500 Pa or -3000 Pa, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] (1) The treatment system of the present invention can simultaneously collect the tail gas of the isophthalonitrile process and other unorganized exhaust gases on site, and then sequentially process them through RTO incineration and SCR denitrification, and effectively utilize the waste heat in the tail gas, which can effectively reduce the energy consumption of the system and thus reduce the treatment cost of the enterprise;

[0097] (2) The treatment system of the present invention has high treatment efficiency, produces less nitrogen oxides, and the pollutant removal rate can reach more than 99.5%. x The removal rate is over 91%;

[0098] (3) The treatment system of the present invention also effectively ensures the safe operation of the RTO unit by setting up an emergency treatment unit, avoiding the dangers of temperature runaway and explosion when the exhaust gas concentration is abnormal, which is beneficial to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 This is a system flow chart of a method for treating tail gas from an isophthalonitrile process provided in Example 1 of the present invention.

[0100] The direction of the arrow represents the direction of the material. DETAILED DESCRIPTION

[0101] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0102] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0103] It should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0104] In a specific embodiment, the present invention provides an isophthalonitrile process tail gas treatment system, the treatment system comprising a process tail gas collection unit, a process tail gas mixing unit, an emergency treatment unit, an RTO unit, a tail gas denitrification unit, a tail gas cooling unit, and a tail gas discharge unit;

[0105] The process tail gas collection unit, the process tail gas mixing unit, the RTO unit, the tail gas denitrification unit, the tail gas cooling unit and the tail gas emission unit are connected in sequence;

[0106] The process tail gas collection unit is also directly connected to the tail gas emission unit through the emergency treatment unit.

[0107] Furthermore, the process tail gas collection unit includes a scrubbing tower, a premixer and a fire-retardant device connected in sequence; there is no less than one scrubbing tower, and they are arranged in parallel; a spraying device is provided in the scrubbing tower; the fire-retardant device of the process tail gas collection unit is connected to the process tail gas mixing unit and the emergency treatment unit respectively through a three-way valve.

[0108] Furthermore, the process tail gas mixing unit includes an inlet mixing box; and a tail gas concentration detector is provided on the pipeline between the process tail gas mixing unit and the RTO unit.

[0109] Furthermore, the RTO unit includes a system fan, an RTO furnace, and an outlet mixing box connected in sequence; the inlet mixing box of the process tail gas mixing unit is connected to the system fan of the RTO unit;

[0110] Furthermore, the RTO furnace includes a bottom cavity, an air exchange valve, a heat storage chamber, a combustion chamber, a combustion string and a combustion-supporting fan; the system fan and the outlet mixing box are independently connected to the RTO furnace through the bottom cavity; the RTO furnace has no less than 3 heat storage chambers, and each of the heat storage chambers is independently filled with a heat storage body; the filling height of the heat storage body is 500 to 1200 mm; the top and bottom of the heat storage body are independently provided with saddle ring layers; adjacent heat storage chambers are connected by arches, and the top of the arch of each heat storage chamber is higher than the heat storage body; the combustion chamber of the RTO furnace is also independently connected to the exhaust gas mixing unit and the outlet mixing box through a bypass pipeline.

[0111] Furthermore, the exhaust gas denitrification unit includes an ammonia injection device, a static mixer and a denitrification reactor connected in sequence; the outlet mixing box of the RTO unit is connected to the static mixer of the exhaust gas denitrification unit; the denitrification reactor includes a vertical reactor; a denitrification catalyst is arranged in the denitrification reactor; the number of layers of the denitrification catalyst is not less than 2 layers; each layer of the denitrification catalyst is provided with an acoustic pulse dust removal device; the type of the denitrification catalyst is a medium and high temperature type.

[0112] Furthermore, the tail gas cooling unit includes a tail gas heat exchanger and a water spray cooling tower connected in sequence; the denitration reactor of the tail gas denitration unit is connected to the tail gas heat exchanger of the tail gas cooling unit.

[0113] Furthermore, the tail gas discharge unit includes an induced draft fan and a chimney connected in sequence; the water spray cooling tower of the tail gas cooling unit is connected to the induced draft fan of the tail gas discharge unit.

[0114] Furthermore, the emergency treatment unit includes an adsorption tower and a water spray tower connected in sequence; the adsorption tower is an activated carbon adsorption tower; the water spray tower of the emergency treatment unit is connected to the induced draft fan of the tail gas emission unit.

[0115] Furthermore, the treatment system also includes an unorganized emission tail gas collection unit; the unorganized emission tail gas collection unit includes an unorganized emission tail gas main pipe and an unorganized emission tail gas collection branch pipe directly connected to the unorganized emission tail gas main pipe; the number of the unorganized emission tail gas collection branch pipe is at least 1; the unorganized emission tail gas main pipe of the unorganized emission tail gas collection unit is connected to the inlet mixing box of the process tail gas mixing unit through the tail gas heat exchanger of the tail gas cooling unit.

[0116] The following are typical but non-limiting examples of the present invention:

[0117] Example 1:

[0118] This embodiment provides an isophthalonitrile process tail gas treatment system and treatment method, based on the treatment system provided in the specific embodiment:

[0119] Wherein, there is one scrubbing tower;

[0120] The RTO furnace has three regenerators, and the filling height of the regenerator is 500 mm;

[0121] The number of layers of the denitration catalyst is 2;

[0122] There are three branch pipes for collecting the unorganized exhaust gas.

[0123] The processing method includes the following steps. The system flow chart of the processing method is as follows: Figure 1 As shown;

[0124] The isophthalonitrile process tail gas in this embodiment is the process tail gas produced by the amination process, with a total of 1 set of production equipment;

[0125] (1) The temperature of the above process tail gas after scrubbing is 35℃, and then it enters the pre-mixer for mixing. After mixing, the negative pressure of the process tail gas main pipe is controlled to be -1000Pa, among which the ammonia content is 15000mg / m 3 , the process tail gas is sequentially transported to the inlet mixing box after passing through tail gas detection, fire arresting equipment and three-way valve;

[0126] The room-temperature unorganized exhaust gas passes through various branches and converges into the unorganized exhaust gas main pipe. The negative pressure of the unorganized exhaust gas main pipe is controlled at -800Pa. The unorganized exhaust gas is transported to the exhaust heat exchanger to exchange heat with the exhaust gas after denitration. The inlet temperature of the hot side of the exhaust heat exchanger is 300℃, and the outlet temperature of the hot side is 190℃. The temperature of the unorganized exhaust gas after heat exchange is 200℃ and is transported to the inlet mixing box.

[0127] Among them, the ratio of process exhaust air volume to fugitive exhaust air volume is 1:1.5;

[0128] (2) The two types of exhaust gas are fully mixed in the inlet mixing box, and the outlet temperature of the inlet mixing box is controlled to 150°C by the high-temperature discharge valve. Then, the exhaust gas is sent to the RTO furnace through the system fan for combustion treatment. The residence time of the two types of exhaust gas in the combustion chamber of the RTO furnace is 1.2 seconds, and the temperature of the combustion chamber of the RTO furnace is controlled at 800°C. The exhaust gas after combustion is divided into three parts. The first part is directly discharged to the outlet mixing box, the second part returns to the inlet mixing box, and the third part passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and is then discharged to the outlet mixing box. The temperature of the outlet mixing box is controlled to be 300°C.

[0129] (3) The tail gas in the outlet mixing box and the ammonia in the ammonia injection equipment enter the static mixed gas for mixing, and denitrification is performed after mixing;

[0130] (4) After denitrification, the exhaust gas passes through the exhaust heat exchanger and exchanges heat with the unorganized exhaust gas, and the temperature drops to 190℃. It then passes through the water spray cooling tower to reduce the temperature to 150℃, and then is sent to the chimney for discharge through the induced draft fan. The induced draft fan controls the pressure at the outlet of the water spray cooling tower to -1500Pa to ensure smooth air flow of the system.

[0131] Example 2:

[0132] This embodiment provides an isophthalonitrile process tail gas treatment system and treatment method, based on the treatment system provided in the specific embodiment:

[0133] Wherein, there are 2 scrubbing towers;

[0134] The RTO furnace has five regenerators, and the filling height of the regenerator is 1200 mm.

[0135] The number of layers of the denitration catalyst is 4;

[0136] There are three branch pipes for collecting the unorganized exhaust gas.

[0137] The processing method comprises the following steps:

[0138] The isophthalonitrile process tail gas in this embodiment is the process tail gas produced by the amination process, with a total of 2 sets of production equipment;

[0139] (1) The temperature of the above process tail gas after scrubbing is 55℃, and then it enters the pre-mixer for mixing. After mixing, the negative pressure of the process tail gas main pipe is controlled to be -800Pa, among which the ammonia content is 12000mg / m 3 , the process tail gas is sequentially transported to the inlet mixing box after passing through tail gas detection, fire arresting equipment and three-way valve;

[0140] The room-temperature unorganized exhaust gas is merged into the unorganized exhaust gas main pipe through various branches. The negative pressure of the unorganized exhaust gas main pipe is controlled to -800Pa. The unorganized exhaust gas is transported to the exhaust heat exchanger to exchange heat with the exhaust gas after denitration. The inlet temperature of the hot side of the exhaust heat exchanger is 320℃, and the outlet temperature of the hot side is 190℃. After heat exchange, the temperature of the unorganized exhaust gas is 190℃ and it is transported to the inlet mixing box.

[0141] Among them, the ratio of process exhaust air volume to fugitive exhaust air volume is 1:2;

[0142] (2) The two types of exhaust gas are fully mixed in the inlet mixing box, and the outlet temperature of the inlet mixing box is controlled to 160°C by the high-temperature discharge valve. Then, the exhaust gas is sent to the RTO furnace through the system fan for combustion treatment. The residence time of the two types of exhaust gas in the combustion chamber of the RTO furnace is 1.5 seconds, and the temperature of the combustion chamber of the RTO furnace is controlled at 850°C. The exhaust gas after combustion is divided into three parts. The first part is directly discharged to the outlet mixing box, the second part returns to the inlet mixing box, and the third part passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and is then discharged to the outlet mixing box. The temperature of the outlet mixing box is controlled to be 320°C.

[0143] (3) The tail gas in the outlet mixing box and the ammonia in the ammonia injection equipment enter the static mixed gas for mixing, and denitrification is performed after mixing;

[0144] (4) After denitrification, the exhaust gas passes through the exhaust heat exchanger and exchanges heat with the unorganized exhaust gas, and the temperature drops to 190℃. It then passes through the water spray cooling tower to reduce the temperature to 165℃, and then is sent to the chimney for discharge through the induced draft fan. The induced draft fan controls the pressure at the outlet of the water spray cooling tower to -1200Pa to ensure smooth air flow of the system.

[0145] Example 3:

[0146] This embodiment provides an isophthalonitrile process tail gas treatment system and treatment method, based on the treatment system provided in the specific embodiment:

[0147] Wherein, there are 3 scrubbing towers;

[0148] The RTO furnace has three regenerators, and the filling height of the regenerator is 1000 mm;

[0149] The number of layers of the denitration catalyst is 5;

[0150] There are two branch pipes for collecting the unorganized exhaust gas.

[0151] The processing method comprises the following steps:

[0152] The isophthalonitrile process tail gas in this embodiment is the process tail gas produced by the amination process, a total of 3 sets of production equipment

[0153] (1) The temperature of the above process tail gas after scrubbing is 60℃, and then it enters the pre-mixer for mixing. After mixing, the negative pressure of the process tail gas main pipe is controlled to be -1000Pa, among which the ammonia content is 20000mg / m 3 , the process tail gas is sequentially transported to the inlet mixing box after passing through tail gas detection, fire arresting equipment and three-way valve;

[0154] The room-temperature unorganized exhaust gas passes through various branches and converges into the unorganized exhaust gas main pipe. The negative pressure of the unorganized exhaust gas main pipe is controlled at -600Pa. The unorganized exhaust gas is transported to the exhaust heat exchanger to exchange heat with the exhaust gas after denitration. The inlet temperature of the hot side of the exhaust heat exchanger is 360℃, and the outlet temperature of the hot side is 185℃. The temperature of the unorganized exhaust gas after heat exchange is 200℃ and is transported to the inlet mixing box.

[0155] Among them, the ratio of process exhaust air volume to fugitive exhaust air volume is 1:3;

[0156] (2) The two types of exhaust gas are fully mixed in the inlet mixing box, and the outlet temperature of the inlet mixing box is controlled to 155°C by the high-temperature discharge valve. Then, the exhaust gas is sent to the RTO furnace through the system fan for combustion treatment. The residence time of the two types of exhaust gas in the combustion chamber of the RTO furnace is 2 seconds, and the temperature of the combustion chamber of the RTO furnace is controlled at 830°C. The exhaust gas after combustion is divided into three parts. The first part is directly discharged to the outlet mixing box, the second part returns to the inlet mixing box, and the third part passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and is then discharged to the outlet mixing box. The temperature of the outlet mixing box is controlled to be 350°C.

[0157] (3) The tail gas in the outlet mixing box and the ammonia in the ammonia injection equipment enter the static mixed gas for mixing, and denitrification is performed after mixing;

[0158] (4) After denitrification, the exhaust gas passes through the exhaust heat exchanger and exchanges heat with the unorganized exhaust gas, and the temperature drops to 185℃. It then passes through the water spray cooling tower to reduce the temperature to 155℃, and then is sent to the chimney for discharge through the induced draft fan. The induced draft fan controls the pressure at the outlet of the water spray cooling tower to -1000Pa to ensure smooth air flow of the system.

[0159] Comparative Example 1:

[0160] This comparative example provides an isophthalonitrile process tail gas treatment system and treatment method. The system device refers to the system device in Example 1, with the following differences:

[0161] 1) The combustion chamber of the RTO furnace is not provided with a bypass pipeline to the inlet mixing box and the outlet mixing box;

[0162] 2) To ensure the denitration reaction proceeds, the type of denitration catalyst used is a low-temperature type;

[0163] 3) The exhaust gas cooling unit only includes an exhaust gas heat exchanger, and no water spray cooling tower is required;

[0164] The processing method comprises the following steps:

[0165] The isophthalonitrile process tail gas in this comparative example is the process tail gas produced by the amination process, which is the same as that in Example 1.

[0166] (1) The temperature of the above process tail gas after scrubbing is 35℃, and then it enters the pre-mixer for mixing. After mixing, the negative pressure of the process tail gas main pipe is controlled to be -1000Pa, among which the ammonia content is 15000mg / m 3 , the process tail gas is sequentially transported to the inlet mixing box after passing through tail gas detection, fire arresting equipment and three-way valve;

[0167] The room-temperature unorganized exhaust gas passes through various branches and converges into the unorganized exhaust gas main pipe. The negative pressure of the unorganized exhaust gas main pipe is controlled at -800Pa. The unorganized exhaust gas is transported to the exhaust heat exchanger to exchange heat with the exhaust gas after denitration. The inlet temperature of the hot side of the exhaust heat exchanger is 100℃, and the outlet temperature of the hot side is 60℃. After heat exchange, the temperature of the unorganized exhaust gas is 90℃ and is transported to the inlet mixing box.

[0168] Among them, the ratio of process exhaust air volume to fugitive exhaust air volume is 1:1.5;

[0169] (2) The two types of exhaust gas are fully mixed in the inlet mixing box, and the temperature after mixing is 65℃. Then, they are sent to the RTO furnace for combustion through the system fan. The residence time of the two types of exhaust gas in the RTO furnace combustion chamber is 1.2 seconds, and the temperature of the RTO furnace combustion chamber is controlled at 800℃. The exhaust gas after combustion passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and is then discharged to the outlet mixing box. At this time, the temperature of the outlet mixing box is only 100℃.

[0170] (3) The tail gas in the outlet mixing box and the ammonia in the ammonia injection equipment enter the static mixed gas for mixing, and denitrification is performed after mixing;

[0171] (4) After denitrification, the exhaust gas passes through the exhaust heat exchanger and exchanges heat with the unorganized exhaust gas, and the temperature drops to 60°C. Then it is directly sent to the chimney for discharge through the induced draft fan. The induced draft fan controls the pressure at the outlet of the exhaust heat exchanger to -1500Pa to ensure smooth air flow of the system.

[0172] The pollutant removal rates of the treatment methods described in Examples 1-3 and Comparative Example 1 were measured, and the results are shown in Table 1.

[0173] Table 1

[0174]

[0175]

[0176] As can be seen in Table 1, in Comparative Example 1, the RTO furnace combustion chamber lacks a high-temperature bypass, making it impossible to maintain the temperatures of the inlet and outlet mixing boxes. The RTO unit's inlet and exhaust temperatures are both relatively low, and pollutants in the exhaust gas easily crystallize and polymerize at these temperatures, leading to blockage of the RTO furnace inlet piping, fan impeller, RTO bottom chamber, and lower heat storage body. The low outlet mixing box temperature also affects the selection of denitration catalysts. Low-temperature catalysts are much more expensive than medium- and high-temperature catalysts, and their denitration performance is suboptimal, with a NOx removal rate of only 30%. The low exhaust temperature after denitration affects the heat transfer efficiency of the low-temperature heat exchanger, preventing adequate preheating of the fugitive exhaust gas. This results in poor overall RTO system performance.

[0177] From the above embodiments and comparative examples, it can be seen that the treatment system of the present invention can simultaneously collect the tail gas of the isophthalonitrile process and other unorganized exhaust gases on site, and then sequentially carry out RTO incineration and SCR denitrification treatment, and effectively utilize the waste heat in the tail gas, which can effectively reduce the energy consumption of the system and thus reduce the treatment cost of the enterprise; the treatment system of the present invention has high treatment efficiency, produces less nitrogen oxides, and the pollutant removal rate can reach more than 99.5%, NO x The removal rate is over 91%. The treatment system also effectively ensures the safe operation of the RTO unit by setting up an emergency treatment unit, avoiding the dangers of temperature runaway and explosion when the exhaust gas concentration is abnormal, which is conducive to industrial production.

[0178] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed methods of the present invention. However, the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the operations of the present invention, additions of auxiliary operations, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. An isophthalonitrile process tail gas treatment system, characterized in that, The treatment system includes a process tail gas collection unit, a process tail gas mixing unit, an emergency treatment unit, an RTO unit, a tail gas denitrification unit, a tail gas cooling unit and a tail gas emission unit; The process tail gas collection unit, the process tail gas mixing unit, the RTO unit, the tail gas denitrification unit, the tail gas cooling unit and the tail gas emission unit are connected in sequence; An exhaust gas concentration detector is provided on the pipeline between the process exhaust gas mixing unit and the RTO unit; The RTO unit includes a system fan, an RTO furnace and an outlet mixing box connected in sequence; the inlet mixing box of the process tail gas mixing unit is connected to the system fan of the RTO unit; The RTO furnace includes a bottom cavity, an air exchange valve, a regenerator, a combustion chamber, a combustion train, and a combustion-supporting blower; the system blower and the outlet mixing box are independently connected to the RTO furnace through the bottom cavity; adjacent regenerators are connected by arches, and the top of the arch of each regenerator is higher than the regenerator; the combustion chamber of the RTO furnace is also independently connected to the exhaust gas mixing unit and the outlet mixing box through a bypass pipeline; The fire-blocking device of the process tail gas collection unit is connected to the process tail gas mixing unit and the emergency treatment unit respectively through a three-way valve; The emergency treatment unit includes an adsorption tower and a water spray tower connected in sequence; the water spray tower of the emergency treatment unit is connected to the induced draft fan of the tail gas emission unit.

2. The processing system according to claim 1, wherein: The process tail gas collection unit includes a scrubber, a premixer and a fire arrester which are connected in sequence.

3. The processing system according to claim 2, characterized in that There is no less than one scrubbing tower, and they are arranged in parallel.

4. The processing system according to claim 2, characterized in that A spraying device is provided in the scrubbing tower.

5. The processing system according to claim 1, wherein: The RTO furnace has no less than 3 regenerators.

6. The processing system according to claim 1, wherein: Each of the heat storage chambers is independently filled with a heat storage body.

7. The processing system according to claim 6, characterized in that The filling height of the heat storage body is 500-1200 mm.

8. The processing system according to claim 1, wherein: The top and bottom of the heat storage body are independently provided with saddle ring layers.

9. The processing system according to claim 1, wherein: The tail gas denitration unit includes an ammonia injection device, a static mixer and a denitration reactor which are connected in sequence.

10. The processing system according to claim 1, wherein: The outlet mixing box of the RTO unit is connected to the static mixer of the tail gas denitration unit.

11. The processing system according to claim 9, wherein: The denitration reactor includes a vertical reactor.

12. The processing system according to claim 9, wherein: A denitration catalyst is arranged in the denitration reactor.

13. The processing system according to claim 12, characterized in that The number of layers of the denitration catalyst is no less than 2.

14. The processing system according to claim 13, characterized in that Each layer of denitrification catalyst is equipped with an acoustic pulse dust removal device.

15. The processing system according to claim 12, wherein: The denitration catalyst is of medium-high temperature type.

16. The processing system according to claim 1, wherein: The tail gas cooling unit includes a tail gas heat exchanger and a water spray cooling tower connected in sequence.

17. The processing system according to claim 1, wherein: The denitration reactor of the tail gas denitration unit is connected to the tail gas heat exchanger of the tail gas cooling unit.

18. The processing system according to claim 1, wherein: The tail gas discharge unit includes an induced draft fan and a chimney connected in sequence.

19. The processing system according to claim 1, wherein: The water spray cooling tower of the tail gas cooling unit is connected to the induced draft fan of the tail gas discharge unit.

20. The processing system according to claim 1, wherein The adsorption tower includes an activated carbon adsorption tower.

21. The processing system according to claim 1, wherein The treatment system also includes a fugitive emission tail gas collection unit.

22. The processing system according to claim 21, characterized in that The fugitive exhaust gas collection unit includes a fugitive exhaust gas main pipe and a fugitive exhaust gas collection branch pipe directly connected to the fugitive exhaust gas main pipe.

23. The processing system according to claim 22, characterized in that There is at least one branch pipe for collecting the unorganized exhaust gas.

24. The processing system according to claim 22, wherein: The unorganized exhaust gas main pipe of the unorganized exhaust gas collection unit is connected to the inlet mixing box of the process exhaust gas mixing unit through the exhaust gas heat exchanger of the exhaust gas cooling unit.

25. A method for treating tail gas from an isophthalonitrile process, characterized in that: The processing method is performed using the processing system according to any one of claims 1 to 24, and the processing method comprises the following steps: Collect the isophthalonitrile process tail gas, and then carry out combustion, denitrification and cooling in sequence before discharging; When abnormal exhaust gas concentration is detected, the collected isophthalonitrile process exhaust gas will be switched to the emergency treatment unit and discharged after emergency treatment.

26. The processing method according to claim 25, characterized in that The processing method is more specifically carried out in the following steps: (1) The isophthalonitrile process tail gas is premixed after scrubbing, and the pressure in the main pipe after premixing is controlled to be negative pressure, and then enters the inlet mixing box through the fire-retardant facility and the three-way valve in sequence; Collect unorganized exhaust gas, control the pressure in the main pipe to be negative, and then enter the inlet mixing box after heat exchange in the exhaust heat exchanger; (2) The two types of exhaust gas in step (1) are mixed and transported to the RTO furnace through the system fan, and then pass through the bottom cavity and the first regenerator from bottom to top to enter the combustion chamber for combustion. The exhaust gas after combustion is divided into three parts, the first part is directly discharged to the outlet mixing box, the second part returns to the inlet mixing box, and the third part passes through the second regenerator and the bottom cavity from top to bottom in the RTO furnace and then is discharged to the outlet mixing box; (3) The tail gas in the outlet mixing box of step (2) and the ammonia in the ammonia spraying equipment enter into a static mixed gas for mixing, and denitrification is performed after mixing; (4) The denitrified tail gas is heat exchanged with the unorganized exhaust gas in step (1), and then discharged after being cooled by water spraying; When abnormality is detected in the tail gas in the inlet mixing box, the three-way valve is switched to the emergency treatment unit, so that the process tail gas in step (1) is discharged after passing through the adsorption tank and the water spray tower in sequence.

27. The processing method according to claim 26, characterized in that The ammonia content in the isophthalonitrile process tail gas of step (1) is 1000~40000mg / m 3 .

28. The processing method according to claim 26, characterized in that The temperature of the isophthalonitrile process tail gas in step (1) is 30-90°C.

29. The processing method according to claim 26, characterized in that The air volume of the isophthalonitrile process tail gas in step (1) is 8000~50000Nm 3 / h.

30. The processing method according to claim 26, characterized in that The ammonia content in the unorganized exhaust gas of step (1) is 0-5000 mg / m 3 .

31. The processing method according to claim 26, characterized in that The air volume ratio of the unorganized exhaust gas emitted in step (1) to the isophthalonitrile process exhaust gas is 0 to 10.

32. The processing method according to claim 26, characterized in that The temperature of the process tail gas after the scrubbing in step (1) is 20-95°C.

33. The processing method according to claim 26, characterized in that Step (1) controls the pressure in the main pipe after premixing to be -100 to -2500 Pa.

34. The processing method according to claim 26, characterized in that Step (1) controls the pressure in the main pipe of the collected unorganized exhaust gas to be -100 to -2500 Pa.

35. The processing method according to claim 26, characterized in that The temperature of the unorganized exhaust gas after heat exchange in step (1) is 150-250°C.

36. The processing method according to claim 26, characterized in that The temperature of the two types of tail gases after mixing in step (2) is 130-180°C.

37. The processing method according to claim 26, characterized in that The combustion temperature in step (2) is 780-950°C.

38. The processing method according to claim 26, characterized in that During the combustion process in step (2), the residence time of the tail gas is 1 to 3 seconds.

39. The processing method according to claim 26, characterized in that The temperature in the outlet mixing box of step (2) is 250-350°C.

40. The processing method according to claim 26, characterized in that The temperature of the tail gas after denitration in step (3) is 250-350°C.

41. The processing method according to claim 26, characterized in that The temperature of the denitrified tail gas after heat exchange in step (4) is 150-250°C.

42. The processing method according to claim 26, characterized in that The temperature of the tail gas after water spray cooling in step (4) is 120-180°C.

43. The processing method according to claim 26, characterized in that The outlet pressure of the tower for water spray cooling in step (4) is -1000 to -3000 Pa.

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