An integrated RTO device and process for treating VOCs and coordinating denitrification

Abstract

The present invention discloses an integrated RTO device and process for treating VOCs and coordinating denitration. The device includes a connected combustion chamber and a plurality of heat storage chambers. The combustion chamber is located at the upper part of the heat storage chamber. A burner is arranged in the combustion chamber. Each heat storage chamber is provided with a first-stage heat storage body, a second-stage heat storage body loaded with an SCR catalyst, a third-stage heat storage body and a fourth-stage heat storage body from top to bottom. A first-stage reducing agent dispersion device is arranged above the second-stage heat storage body. Each heat storage chamber is independently provided with an inlet valve connected to an organic waste gas pipeline at the input end, an outlet valve connected to a purge air pipeline at the input end, and a purge valve. The process includes the steps: S1 exhaust gas enters the heat storage chamber in the intake working condition through the inlet valve, enters the combustion chamber after being heated by the heat storage chamber, and an oxidation reaction occurs to remove VOCs; S2 exhaust gas then enters the heat storage chamber in the outlet working condition, and is discharged through the outlet valve after denitration; S3 reciprocates to adjust each heat storage chamber to the corresponding required working condition to achieve the treatment and denitration of VOCs.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste gas treatment, and in particular to an integrated RTO device and process for treating VOCs and coordinating denitration. Background Art

[0002] Volatile organic pollutants (VOCs) are widely produced in petrochemical, chemical, industrial coating, packaging and printing, oil storage and transportation, etc. They have multiple environmental effects and are the main sources of ozone (O 3 ) and fine particulate matter (PM 2.5 ) pollution, which has caused great harm to the environment and human health. At present, the commonly used VOCs treatment methods mainly include adsorption, solvent absorption, photocatalysis, low-temperature plasma, catalytic oxidation, incineration and biological treatment. Among them, the regenerator incineration method (RTO) is widely used in the field of VOCs waste gas treatment with large air volume, low concentration and no recovery value due to its high purification efficiency, wide applicability, low operating cost, high degree of automation, simple operation, safe and reliable operation.

[0003] However, RTO may produce NO in actual operation. x , there are certain technical shortcomings. x The generation of NOx: On the one hand, the waste gas itself contains nitrogen, which generates fuel-type NOx in the furnace. x On the other hand, thermal NO is generated in the burner part. x , although this part NO x The amount of NO produced can be reduced to a certain extent by using low-nitrogen burners, but it cannot be completely eliminated. x The generation of NOx is a technical problem that must be overcome in practical applications. There are currently two main solutions to this problem: one is to use a denitration process for post-treatment; the other is to integrate a denitration device into the RTO device.

[0004] The patent specification with publication number CN 209108945 U discloses an ultra-low emission device for flue gas in the non-electrical field, including a main tower with built-in guide plates, filtering and dust removal components, a front RCO / RTO device, a rear RCO / RTO device and an SCR device with an SCR catalyst. The main tower is connected to the front RCO / RTO device and the rear RCO / RTO device respectively through an inlet three-way valve. The RCO / RTO device is connected to the SCR device through a pipeline and an outlet pipeline. The inlet pipeline is provided with a reducing agent dispersion device to achieve the functions of denitrification and removal of VOCs gas.

[0005] The patent specification with the publication number CN 210206450 U discloses a flue gas RTO and SCR denitrification synergistic treatment device with comprehensive utilization of heat energy, including an RTO device and an SCR reactor. The RTO device includes a combustion chamber and at least two heat storage and heat exchange chambers. The high-temperature flue gas outlet of the combustion chamber is divided into two routes. One route enters the SCR reactor through an electromagnetic control valve after heat storage and heat exchange in one of the heat storage and heat exchange chambers. The flue gas purified by the SCR reactor is connected to the flue gas heat exchanger through the flue duct and discharged after heat exchange in the flue gas heat exchanger. The utility model can jointly remove VOCs and NO in the flue gas. x And other harmful gas components.

[0006] Placing the denitrification process after RTO can effectively remove NO that may be generated by RTO. x However, the exhaust gas temperature at the RTO outlet is relatively low (<100°C) and cannot reach the SCR reaction temperature (generally 200-400°C). Therefore, additional heating equipment is required to heat the exhaust gas, which increases the energy consumption of the entire system and increases operating costs.

[0007] The patent specification with publication number CN 110605019 A discloses a treatment device and process integrating VOCs purification and denitrification, including an RTO reactor, wherein the RTO reactor includes a connected combustion chamber and several heat storage chambers, wherein the combustion chamber is located at the upper part of the heat storage chamber; any heat storage chamber includes an upper heat storage body, a lower heat storage body and an intermediate SCR catalyst bed; and the bottom of any heat storage chamber is provided with an air intake valve, an exhaust valve and a purge valve; the input end of the air intake valve is connected to a buffer tank, and the buffer tank is connected to a VOCs waste gas pipeline and an ammonia pipeline; the input end of the purge valve is connected to a purge gas supply pipeline; a burner is also provided on the top of the combustion chamber, and the input end of the burner is connected to a fuel gas pipeline. Realize VOCs and NO x Ultra-clean emissions.

[0008] This patent integrates SCR and RTO into an integrated device, making full use of the high temperature environment in RTO, and can meet the reaction conditions of SNCR and SCR without secondary heating, thus achieving VOCs and NO x However, in order to ensure the denitrification efficiency, excessive reducing agent needs to be added to the front buffer tank, resulting in a waste of reducing agent; the reducing agent may react with the complex organic gas into the combustion chamber with the exhaust gas to produce a large number of by-products. Compared with VOCs, NO x The concentration is relatively low, and the actual denitrification efficiency is not high; and when the gas composition and content fluctuate, the denitrification effect is unstable. Summary of the invention

[0009] In view of the shortcomings in the art, the present invention provides an integrated RTO device and process for treating VOCs and coordinating denitrification. While making reasonable use of the high temperature environment of RTO, the amount of reducing agent is accurately controlled through detection equipment and control system to ensure stable operation of the system and achieve NO x While co-processing VOCs, it reduces operating costs.

[0010] An integrated RTO process for treating VOCs and synergistically denitrifying is used, and an integrated RTO device for treating VOCs and synergistically denitrifying is used. The integrated RTO device includes a connected combustion chamber and a plurality of heat storage chambers, wherein the combustion chamber is located at the upper part of the heat storage chamber, and a burner is arranged in the combustion chamber. Each of the heat storage chambers is provided with a first-stage heat storage body, a second-stage heat storage body loaded with an SCR catalyst, a third-stage heat storage body, and a fourth-stage heat storage body from top to bottom in sequence, and a first-stage reducing agent dispersion device is arranged above the second-stage heat storage body. Each of the heat storage chambers is independently provided with an air intake valve, an air outlet valve, and a purge valve, and the input end of the air intake valve is connected to an organic waste gas pipeline, and the input end of the purge valve is connected to a purge air pipeline;

[0011] Each of the heat storage chambers has an air intake condition, an air outlet condition and a purge condition; under the air intake condition, the air intake valve of the heat storage chamber is opened, the air outlet valve and the purge valve are closed, and the first-stage reducing agent dispersion device is closed; under the air outlet condition, the air outlet valve of the heat storage chamber is opened, the air intake valve and the purge valve are closed, and the first-stage reducing agent dispersion device is opened, and the reducing agent is sprayed into the heat storage chamber for denitration; under the purge condition, the purge valve of the heat storage chamber is opened, the air intake valve and the air outlet valve are closed, and the first-stage reducing agent dispersion device is closed;

[0012] The integrated RTO process comprises the steps of:

[0013] S1: The exhaust gas enters the regenerator in the intake condition through the intake valve, and then enters the combustion chamber after being heated by the regenerator, where an oxidation reaction occurs to treat VOCs;

[0014] S2: After VOCs treatment, the exhaust gas enters the regenerator in the outlet condition for denitrification, and the denitrified exhaust gas is discharged through the outlet valve;

[0015] S3: Reciprocatingly adjust each heat storage chamber to the corresponding required working condition to achieve VOCs treatment and denitrification.

[0016] In the present invention, the gas outlet valve of the same heat storage chamber is linked with the reducing agent dispersion device. When the gas outlet valve is opened or closed, the reducing agent dispersion device in the corresponding heat storage chamber is opened or closed accordingly. On the one hand, it prevents the reducing agent from entering the combustion chamber and reacting with organic matter to produce by-products, thereby preventing the VOCs removal effect and the subsequent denitrification effect from being affected. On the other hand, it avoids the consumption of excess reducing agent and saves costs.

[0017] In the process of the present invention, the amount of reducing agent added by the first-stage reducing agent dispersing device is determined by design calculation. Preferably, the amount of reducing agent added by the first-stage reducing agent dispersing device is calculated according to the concentration of nitrogen-containing organic matter in the exhaust gas, and the actual amount added is 0-10% excess.

[0018] The heat storage chamber may have two chambers, three chambers or more chambers.

[0019] Preferably, the heat storage body in the heat storage chamber is selected from at least one of a honeycomb ceramic heat storage body, a multilayer plate heat storage body, and a horseshoe cloth air ring.

[0020] Preferably, in step S1, the temperature of the exhaust gas after passing through the heat storage chamber rises to 50-100°C lower than the temperature of the combustion chamber, and the temperature of the combustion chamber is 750-850°C.

[0021] Preferably, the temperature range of the second stage heat storage body is 300-400°C, and the load V 2 O 5 -WO 3 / TiO 2 、V 2 O 5 -MoO 3 / TiO 2 At least one SCR catalyst in the.

[0022] Preferably, the reducing agent is aqueous ammonia and / or urea.

[0023] Preferably, the purge time under the purge condition is 10 to 50 seconds.

[0024] Preferably, the temperature range of the four-stage heat storage body is 120-200°C, at least one SCR catalyst selected from a manganese oxide-based catalyst and a cerium oxide-based catalyst is loaded on the four-stage heat storage body, and a second-stage reducing agent dispersion device and a NO x Detection device;

[0025] Under the air intake condition, the first-stage reducing agent dispersion device and the second-stage reducing agent dispersion device in the heat storage chamber are both closed;

[0026] Under the above-mentioned gas outlet condition, the first-stage reducing agent dispersion device in the heat storage chamber is turned on to spray reducing agent into the heat storage chamber for denitration, and the second-stage reducing agent dispersion device is turned on according to the NO above it. x The detection device detects NO in real time x Data adjusts the amount of reducing agent added;

[0027] Under the purge condition, the first-stage reducing agent dispersion device and the second-stage reducing agent dispersion device in the heat storage chamber are both closed.

[0028] Specifically, when the test result is lower than the emission standard value, the second-stage reducing agent dispersion device is closed; when the test result is higher than the emission standard value, the second-stage reducing agent dispersion device is opened to spray reducing agent in front of the four-stage heat storage body. Furthermore, after the second-stage reducing agent dispersion device is opened, the amount of reducing agent added is determined according to NO x The difference between the real-time concentration and the standard value is calculated. After the second-stage reducing agent dispersion device is turned on, a low-temperature SCR reaction occurs on the four-stage heat storage body.

[0029] Preferably, the NO x The detection device is a temperature-resistant detector, suitable for detecting NO at 200°C. x concentration.

[0030] The integrated RTO process for VOCs treatment and coordinated denitrification of the present invention preferably has three regenerators;

[0031] In a VOCs treatment and coordinated denitrification stage, the three heat storage chambers are respectively in an air intake condition, an air outlet condition and a purge condition;

[0032] The integrated RTO process comprises the steps of:

[0033] S1: The exhaust gas enters the regenerator in the intake condition through the intake valve, and then enters the combustion chamber after being heated by the regenerator, where an oxidation reaction occurs to treat VOCs;

[0034] S2: After VOCs treatment, the exhaust gas enters the regenerator in the outlet condition for denitrification, and the denitrified exhaust gas is discharged through the outlet valve;

[0035] S3: Entering the next VOCs treatment and coordinated denitration stage, the regenerator in the previous stage which was in the air intake condition is adjusted to the purge condition, the regenerator in the air outlet condition is adjusted to the air intake condition, and the regenerator in the purge condition is adjusted to the air outlet condition, to carry out VOCs treatment and denitration;

[0036] S4: Repeat step S3 until the treatment and denitrification of exhaust gas VOCs are completed.

[0037] Compared with the prior art, the present invention has the following main advantages:

[0038] (1) The present invention converts NO x The VOCs treatment is integrated into the integrated RTO device, eliminating the need to add a new denitrification device after the RTO, saving floor space and construction costs.

[0039] (2) The present invention makes full use of the heat of RTO and places the denitration catalyst in a suitable temperature range in the heat storage chamber. On the one hand, there is no need to reheat the exhaust gas, saving energy and operating costs; on the other hand, it ensures that the denitration catalyst reacts at the optimal temperature, thereby improving the catalytic efficiency.

[0040] (3) The present invention links the reducing agent dispersion device with the gas outlet valve, which, on the one hand, prevents the reducing agent from entering the combustion chamber and reacting with organic matter to produce by-products, thereby preventing the VOCs removal effect and subsequent denitrification effect from being affected; on the other hand, it avoids the consumption of excess reducing agent and saves costs.

[0041] (4) The present invention provides a two-stage reducing agent dispersion device to ensure stable NO even when the organic matter concentration fluctuates. x Treatment effect, by NO x The detection device and control system reasonably control the amount of reducing agent added, reducing costs while ensuring high denitrification efficiency.

[0042] In summary, the present invention combines VOCs thermal storage combustion treatment with SCR denitrification, applies the heat of the RTO device to the SCR reaction, and the outlet valve of the same thermal storage chamber is linked with the reducing agent dispersion device to remove NO generated by combustion. x , effectively reducing energy consumption and achieving VOCs and NO x Collaborative removal, through the detection instrument and control system to adjust the amount of reducing agent added, increase the utilization efficiency of the reducing agent in the SCR, at the same time, ensure the outlet NO x And VOCs stably meet the standards, reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the structure of an integrated three-chamber RTO device for VOCs treatment and coordinated denitrification according to the present invention;

[0044] In the figure: 1-combustion chamber; 11-low nitrogen burner; 2-first heat storage chamber; 21-first stage heat storage body; 22-second stage heat storage body; 23-third stage heat storage body; 24-fourth stage heat storage body; 25-first stage reducing agent dispersion device; 26-second stage reducing agent dispersion device; 27-NO x Detection device; 3-second heat storage chamber; 4-third heat storage chamber; 51-first chamber air inlet valve; 52-second chamber air inlet valve; 53-third chamber air inlet valve; 61-first chamber air outlet valve; 62-second chamber air outlet valve; 63-third chamber air inlet valve; 71-first chamber purge valve; 72-second chamber purge valve; 73-third chamber purge valve. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0046] The structure of the integrated three-chamber RTO device for VOCs treatment and coordinated denitrification in this embodiment is as follows Figure 1 As shown, it includes a connected combustion chamber 1 and three heat storage chambers, and the three heat storage chambers are respectively a first heat storage chamber 2, a second heat storage chamber 3 and a third heat storage chamber 4.

[0047] The combustion chamber 1 is located at the upper part of the three regenerators. A low-nitrogen burner 11 is arranged in the combustion chamber 1. The temperature in the combustion chamber 1 is 750-850°C.

[0048] Each heat storage chamber is provided with a first-stage heat storage body 21, a second-stage heat storage body 22, a third-stage heat storage body 23 and a fourth-stage heat storage body 24 from top to bottom. Each stage of the heat storage body is installed on the grid plate from top to bottom. The material of the heat storage body is a ceramic honeycomb body.

[0049] A first-stage reducing agent dispersion device 25 is provided above the second-stage heat storage body 22, and a second-stage reducing agent dispersion device 26 and NO are provided above the fourth-stage heat storage body 24. x The temperature range of the second stage heat storage body 22 is 300-400°C, and the load V on the second stage heat storage body 22 is 2 O 5 -WO 3 / TiO 2 The temperature range of the four-stage heat storage body 24 is 120-200°C, and the four-stage heat storage body 24 is loaded with Ce-Mn oxide SCR catalyst. The reducing agent used in this embodiment is ammonia water, and the two-stage reducing agent dispersion device is connected to the external storage tank by a pipeline. After receiving the central control spray command, the pump sprays the ammonia water into the corresponding heat storage chamber. NO x The detection device 27 is a temperature-resistant remote transmission function detector that transmits real-time data to the central control.

[0050] Each heat storage chamber has an air inlet pipe, an air outlet pipe and a purge pipe, each pipe is controlled by a valve, and all valves are start valves. Taking the first heat storage chamber 2 as an example, when it is in the air intake condition, the first chamber air inlet valve 51 is opened, and the exhaust gas enters the first heat storage chamber 2 through the air intake pipe. At this time, the first chamber air outlet valve 61 and the first chamber purge valve 71 are closed, and the exhaust gas is heated to about 700°C through 4 sections of heat storage bodies, enters the combustion chamber 1, and an oxidation reaction occurs; when it is in the purge condition, the first chamber purge valve 71 is opened, the first chamber air inlet valve 51 and the first chamber air outlet valve 61 are closed, and the purge wind enters the first heat storage chamber 2 through the pipe for purge, and the purge time is the same as the air intake time; when it is in the air outlet condition, the first chamber air outlet valve 61 is opened, the first chamber air inlet valve 51 and the first chamber purge valve 71 are closed, and the treated clean gas is discharged from the exhaust pipe.

[0051] All of the above valves are equipped with remote transmission function, and their opening and closing can be controlled in the central control system.

[0052] Each heat storage chamber has an air intake condition, an air outlet condition and a purge condition; under the air intake condition, the air intake valve of the heat storage chamber is opened, the air outlet valve and the purge valve are closed, and the first-stage reducing agent dispersion device is closed; under the air outlet condition, the air outlet valve of the heat storage chamber is opened, the air intake valve and the purge valve are closed, and the first-stage reducing agent dispersion device is opened, and the reducing agent is sprayed into the heat storage chamber for denitration; under the purge condition, the purge valve of the heat storage chamber is opened, the air intake valve and the air outlet valve are closed, and the first-stage reducing agent dispersion device is closed.

[0053] The integrated three-chamber RTO device for VOCs treatment and coordinated denitration of this embodiment is used to carry out the integrated RTO process for VOCs treatment and coordinated denitration. In a VOCs treatment and coordinated denitration stage, the three regenerators are respectively in the air intake condition, the air outlet condition and the purge condition, which specifically includes the following steps:

[0054] S1: The exhaust gas enters the regenerator in the intake condition through the intake valve, and then enters the combustion chamber after being heated by the regenerator, where an oxidation reaction occurs to treat VOCs;

[0055] S2: After VOCs treatment, the exhaust gas enters the regenerator in the outlet condition for denitrification, and the denitrified exhaust gas is discharged through the outlet valve;

[0056] S3: Entering the next VOCs treatment and coordinated denitration stage, the regenerator in the previous stage which was in the air intake condition is adjusted to the purge condition, the regenerator in the air outlet condition is adjusted to the air intake condition, and the regenerator in the purge condition is adjusted to the air outlet condition, to carry out VOCs treatment and denitration;

[0057] S4: Repeat step S3 until the treatment and denitrification of exhaust gas VOCs are completed.

[0058] The specific process of the integrated RTO process of this embodiment is shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] In actual operation, the above three processes are carried out in a cycle.

[0063] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An integrated RTO process for treating VOCs and coordinating denitrification, characterized in that: An integrated RTO device for treating VOCs and coordinating denitration is used, the integrated RTO device comprising a connected combustion chamber and a plurality of heat storage chambers, the combustion chamber being located at the upper part of the heat storage chamber, the combustion chamber being provided with a burner, each of the heat storage chambers being provided with a first-stage heat storage body, a second-stage heat storage body loaded with an SCR catalyst, a third-stage heat storage body and a fourth-stage heat storage body from top to bottom, the temperature range of the second-stage heat storage body being 300-400°C, the second-stage heat storage body being loaded with at least one SCR catalyst selected from V2O5-WO3 / TiO2 and V2O5-MoO3 / TiO2, a first-stage reducing agent dispersion device being provided above the second-stage heat storage body, the temperature range of the fourth-stage heat storage body being 120-200°C, the fourth-stage heat storage body being loaded with at least one SCR catalyst selected from manganese oxide-based catalyst and cerium oxide-based catalyst, a second-stage reducing agent dispersion device and NO are provided above the fourth-stage heat storage body x Detection device, each heat storage chamber is independently provided with an air inlet valve, an air outlet valve and a purge valve, the input end of the air inlet valve is connected to the organic waste gas pipeline, and the input end of the purge valve is connected to the purge air pipeline; Each of the heat storage chambers has an intake condition, an exhaust condition and a purge condition; under the intake condition, the intake valve of the heat storage chamber is opened, the exhaust valve and the purge valve are closed, and the first-stage reducing agent dispersion device and the second-stage reducing agent dispersion device are both closed; under the exhaust condition, the exhaust valve of the heat storage chamber is opened, the intake valve and the purge valve are closed, and the first-stage reducing agent dispersion device is opened, and the reducing agent is sprayed into the heat storage chamber for denitration, and the reducing agent addition amount of the first-stage reducing agent dispersion device is calculated according to the concentration of nitrogen-containing organic matter in the exhaust gas, and the actual addition amount is 0-10% excessive, and the second-stage reducing agent dispersion device is calculated according to the NO above it. x The detection device detects NO in real time x The amount of reducing agent added is adjusted by data; under the purge condition, the purge valve of the heat storage chamber is opened, the air inlet valve and the air outlet valve are closed, and the first-stage reducing agent dispersion device and the second-stage reducing agent dispersion device are both closed; The integrated RTO process comprises the steps of: S1: The exhaust gas enters the regenerator in the intake condition through the intake valve, and then enters the combustion chamber after being heated by the regenerator, where an oxidation reaction occurs to treat VOCs; S2: After VOCs treatment, the exhaust gas enters the regenerator in the outlet condition for denitrification, and the denitrified exhaust gas is discharged through the outlet valve; S3: Reciprocatingly adjust each heat storage chamber to the corresponding required working condition to achieve VOCs treatment and denitrification.

2. The integrated RTO process according to claim 1, characterized in that: The heat storage body in the heat storage chamber is selected from at least one of a honeycomb ceramic heat storage body, a multi-layer plate heat storage body, and a horseshoe cloth air ring.

3. The integrated RTO process according to claim 1, characterized in that: In step S1, the temperature of the exhaust gas after passing through the heat storage chamber rises to 50-100°C lower than the temperature of the combustion chamber, and the temperature of the combustion chamber is 750-850°C.

4. The integrated RTO process according to claim 1, characterized in that: The reducing agent is ammonia water and / or urea.

5. The integrated RTO process according to claim 1, characterized in that: The purge time under the purge working condition is 10 to 50 seconds.

6. The integrated RTO process according to claim 1, characterized in that: There are three heat storage chambers; In a VOCs treatment and coordinated denitrification stage, the three heat storage chambers are respectively in an air intake condition, an air outlet condition and a purge condition; The integrated RTO process comprises the steps of: S1: The exhaust gas enters the regenerator in the intake condition through the intake valve, and then enters the combustion chamber after being heated by the regenerator, where an oxidation reaction occurs to treat VOCs; S2: After VOCs treatment, the exhaust gas enters the regenerator in the outlet condition for denitrification, and the denitrified exhaust gas is discharged through the outlet valve; S3: Entering the next VOCs treatment and coordinated denitration stage, the regenerator in the previous stage which was in the air intake condition is adjusted to the purge condition, the regenerator in the air outlet condition is adjusted to the air intake condition, and the regenerator in the purge condition is adjusted to the air outlet condition, to carry out VOCs treatment and denitration; S4: Repeat step S3 until the treatment and denitrification of exhaust gas VOCs are completed.

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