Cyclic adsorption and desorption treatment system for low-concentration organic waste gas

Abstract

The utility model discloses a kind of for low concentration organic waste gas's cyclic adsorption and desorption management system, including adsorption concentration device, hot desorption module, gas shunting module and thermal oxidation module.The adsorption concentration device is equipped with the adsorption zone and desorption zone of alternate operation, for continuous adsorption and desorption organic pollutant;Hot desorption module is connected to desorption zone, and desorption is carried out to desorption zone by heating device;Gas shunting module is connected in hot desorption module export end, and the first pipeline and second pipeline of adjustable outlet gas proportion are configured, first pipeline mixes back part of desorption waste gas to adsorption zone entrance to improve inlet concentration, and second pipeline sends remaining waste gas to thermal oxidation module and carries out oxidation treatment.The system is by dynamic adjustment mixing back proportion and desorption temperature, maintains thermal oxidation module self-heat operation, without external heat source supplement, realizes the efficient management of low concentration organic waste gas and energy-saving operation.

Description

Technical Field

[0001] This utility model relates to the field of waste gas treatment technology, and more specifically, to a circulating adsorption-desorption treatment system for low-concentration organic waste gas. Background Technology

[0002] For large volumes of low-concentration organic waste gas, zeolite rotors are currently widely used as the mainstream process. However, they are mainly limited by the low concentration ratio of the rotor (generally ≤20 times). After concentration, the VOCs enter the downstream thermal oxidation treatment equipment such as CO / RTO / RCO. In actual operation, the heat released by the concentrated VOCs cannot meet the system's self-heating operation, and the entire system still consumes a lot of energy, resulting in high annual operating costs.

[0003] The system's energy consumption is mainly divided into electrical consumption and heat consumption. Electrical consumption primarily refers to the work done by the fan in transporting large volumes of exhaust gas. Under normal operating conditions, the air volume is essentially constant, therefore, electrical energy consumption is relatively stable. Heat consumption is mainly used for deheating the rotor and supplementing the oxidation process, thereby obtaining the oxidation initiation temperature required for the oxidation reaction.

[0004] Therefore, how to provide a circulating adsorption-desorption treatment system for low-concentration organic waste gas that can reduce heat consumption has become a technical problem that urgently needs to be solved in this field. Utility Model Content

[0005] The purpose of this invention is to provide a circulating adsorption-desorption treatment system for low-concentration organic waste gas that can reduce heat consumption.

[0006] This utility model provides a circulating adsorption-desorption treatment system for low-concentration organic waste gas, comprising:

[0007] An adsorption concentration unit, comprising alternating adsorption and desorption zones, is used for the continuous adsorption and desorption of organic pollutants;

[0008] A thermal desorption module is connected to the desorption zone and is equipped with a heating device to desorb the particles in the desorption zone.

[0009] The gas diversion module is connected to the outlet of the thermal desorption module and is equipped with a first pipeline and a second pipeline with adjustable gas output ratio. The first pipeline will return part of the desorbed waste gas to the inlet of the adsorption zone.

[0010] The thermal oxidation module is connected to the outlet end of the second pipeline and is used for thermal oxidation desorption of waste gas.

[0011] Optionally, the circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a heat exchanger;

[0012] The thermal desorption module also includes desorption ducts for supplying air to the desorption zone;

[0013] The thermal oxidation module also includes a heat exhaust duct;

[0014] The desorption duct and the exhaust duct are connected to the heat exchanger and exchange heat inside the heat exchanger.

[0015] Optionally, the circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a preheater, which is installed on the second pipeline to heat the high-concentration waste gas entering the thermal oxidation module from the second pipeline.

[0016] Optionally, the heat exchanger provides a heat source to the preheater.

[0017] Optionally, the adsorption concentration device is a zeolite rotor with a concentration ratio of 20 to 50 times.

[0018] Optionally, the circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a multi-stage filter, which is installed at the air inlet of the adsorption zone.

[0019] Optionally, the circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a safety control unit; the safety control unit includes:

[0020] An online concentration detector is installed in the desorption outlet pipeline to monitor VOCs concentration in real time.

[0021] The temperature and pressure monitoring unit monitors the inlet temperature of the adsorption zone, the temperature of the desorption zone, and the furnace temperature of the thermal oxidation module.

[0022] Optionally, the safety control unit also includes an interlock controller, which automatically cuts off the return air duct and initiates emergency venting when the desorption outlet concentration exceeds a first preset value or the oxidation furnace temperature exceeds a second preset value.

[0023] Optionally, the desorption temperature of the thermal desorption module is 190-210℃, and the heating gas flow rate is 5%-15% of the gas flow rate in the adsorption zone.

[0024] Optionally, the backmixing ratio of the return air duct is 30%-70%, and an electric proportional valve is configured to adjust the opening degree according to the inlet exhaust gas concentration.

[0025] Based on the technical content disclosed in this utility model, the following beneficial effects are achieved:

[0026] The circulating adsorption-desorption treatment system for low-concentration organic waste gas provided by this utility model employs an adsorption concentration device comprising alternating adsorption and desorption zones. A gas diversion module is installed at the outlet of the thermal desorption module, and a first pipeline and a second pipeline with adjustable gas output ratio are configured. The first pipeline returns part of the desorbed waste gas to the inlet of the adsorption zone. It can be seen that this utility model increases the concentration of the high-concentration waste gas at the desorption outlet by mixing it into the inlet of the rotor at a certain ratio. After being fully mixed with the original waste gas, it is adsorbed again by the rotor, thereby increasing the inlet concentration of the rotor. The gas is then adsorbed and desorbed again by the rotor, thus increasing the overall concentration after concentration. This, in turn, increases the inlet concentration of the thermal oxidation module, thereby increasing the calorific value generated by the thermal oxidation module and reducing the energy required for oxidation heating.

[0027] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present invention and, together with their description, serve to explain the principles of the present invention.

[0029] Figure 1 This is a structural diagram of the circulating adsorption-desorption treatment system of this utility model.

[0030] Explanation of reference numerals in the attached diagram: 1. Multistage filter; 2. Zeolite rotor; 3. Adsorption fan; 4. Heat exchanger; 5. Desorption fan; 6. Electric proportional valve; 7. Preheater; 8. Thermal oxidizer; 9. Combustion fan. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0032] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0034] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0036] At 100,000m 3 / h, 200mg / m 3 Taking exhaust gas conditions as an example, if a zeolite rotor + thermal oxidation (rotor + CO) process is adopted, the estimated annual operating cost is as follows:

[0037]

[0038]

[0039] Based on the above, this utility model optimizes and upgrades traditional processes and equipment to address the problem of high system heat consumption. It consists of the following three parts:

[0040] The process route was optimized by designing a rotary circulation adsorption-desorption system. High-concentration waste gas from the desorption outlet was mixed into the rotary inlet in a certain proportion to increase the concentration at the rotary inlet, and then it was adsorbed and desorbed again by the rotary wheel, thereby improving the overall concentration after concentration.

[0041] Upgrade the zeolite rotor to significantly increase the rotor concentration ratio. Under conditions where air volume, composition, and concentration permit, the rotor concentration ratio can be increased to 20-50 times, fundamentally solving the problems of low concentration and insufficient VOCs heat release after concentration.

[0042] Upgrade the heat exchangers within the system to improve heat exchange efficiency. Commonly used plate heat exchangers on the market have low efficiency, mostly around 60%, which wastes heat resources within the system to some extent. The current method increases heat exchange efficiency to 70% or higher, significantly improving energy utilization.

[0043] See Figure 1 This utility model discloses a circulating adsorption-desorption treatment system for low-concentration organic waste gas, including: an adsorption concentration device, a thermal desorption module, a gas diversion module, a thermal oxidation module, a preheater 7, a heat exchanger 4, and a multi-stage filter 1.

[0044] The adsorption concentration device is a zeolite rotor 2 with a concentration ratio of 20 to 50 times; it includes an adsorption zone and a desorption zone that operate alternately for continuous adsorption and desorption of organic pollutants; the inlet of the adsorption zone is equipped with a multi-stage filter 1 to filter the incoming air of the adsorption zone, and the outlet pipe of the adsorption zone is connected to an adsorption fan 3. The adsorption fan provides adsorption airflow to the adsorption zone of the zeolite rotor 2. The mixed organic waste gas enters the adsorption zone of the rotor for adsorption concentration after pretreatment by the multi-stage filter 1.

[0045] The thermal desorption module includes a desorption fan 5, which is connected to the outlet end of the desorption zone to provide desorption airflow to the desorption zone. A heating device is configured at the inlet of the desorption zone to desorb the desorption zone.

[0046] The gas diversion module is connected to the outlet end of the thermal desorption module. It is equipped with a first pipeline and a second pipeline with adjustable gas output ratio. The first pipeline and the second pipeline are connected in parallel at the outlet end of the desorption fan 5. Each of the first pipeline and the second pipeline is equipped with an electric proportional valve 6. The first pipeline back mixes part of the desorbed waste gas to the inlet of the adsorption zone to adjust and increase the inlet concentration of the waste gas in the adsorption zone, thereby increasing the desorption concentration and ensuring that the concentration of the waste gas entering the thermal oxidation module through the second pipeline meets the standard, thus reducing the heat consumption of the thermal oxidation module.

[0047] The thermal oxidation module is used to process the exhaust gas after thermal oxidation desorption, including the thermal oxidizer 8. The thermal oxidizer 8 is connected to natural gas and a combustion fan 9 to increase the thermal oxidation temperature. The outlet end of the second pipeline is connected to one inlet of the thermal oxidizer 8, and a preheater 7 is installed on the second pipeline to increase the temperature of the exhaust gas entering the thermal oxidizer 8 and improve the thermal oxidation efficiency.

[0048] The thermal desorption module also includes a desorption duct, which is used to supply air to the desorption zone; the thermal oxidation module also includes a heat exhaust duct; the desorption duct and the heat exhaust duct are respectively connected to the heat exchanger 4 and exchange heat in the heat exchanger 4. After heat exchange, the heat in the heat exhaust duct is transferred to the desorption duct. After the airflow temperature in the desorption duct rises, it enters the desorption zone for desorption operation.

[0049] Furthermore, the heat exchanger 4 provides a heat source to the preheater 7, which is installed on the second pipeline to heat the high-concentration waste gas entering the thermal oxidizer 8 through the second pipeline, thereby increasing the inlet temperature of the thermal oxidizer 8 and improving the thermal oxidation efficiency.

[0050] Furthermore, the circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a safety control unit; the safety control unit includes: an online concentration detector, a temperature and pressure detector group, and an interlock controller. The online concentration detector is installed on the desorption outlet pipeline to monitor the VOCs concentration in real time; the temperature and pressure detector group monitors the inlet temperature of the adsorption zone, the temperature of the desorption zone, and the temperature of the oxidation furnace in the thermal oxidation module. The interlock controller is used to automatically cut off the return air pipeline and initiate emergency venting when the desorption outlet concentration exceeds a first preset value or the oxidation furnace temperature exceeds a second preset value.

[0051] Optionally, the desorption temperature of the thermal desorption module is 190℃-210℃, preferably 200℃; the backmixing ratio of the first pipeline is 20%-70%, and an electric proportional valve 6 is configured to adjust the opening degree of the electric proportional valve 6 according to the inlet exhaust gas concentration.

[0052] This utility model also provides an organic waste gas treatment process, which adopts the circulating adsorption-desorption treatment system for low-concentration organic waste gas of the first aspect of this utility model, and includes the following steps:

[0053] Waste gas containing organic pollutants is passed into the adsorption zone for adsorption and purification.

[0054] Hot air at a certain temperature is used to desorb in the desorption zone, generating high-concentration waste gas;

[0055] The desorbed waste gas in a preset ratio is back-mixed to the inlet of the adsorption zone, so that the inlet gas concentration of the adsorption zone is increased to the preset concentration.

[0056] The back-mixing ratio and desorption temperature are dynamically adjusted according to the heat consumption of the thermal oxidation module to maintain the thermal balance of the system, so that the thermal oxidation module does not require external heat source supplementation.

[0057] Furthermore, the process also includes safety interlock control steps:

[0058] When the desorption outlet concentration is greater than 20% LEL, an early warning is triggered and the return air ratio of the first pipeline is reduced.

[0059] When the desorption outlet concentration exceeds 25% LEL or the oxidation furnace temperature exceeds 600℃, the first pipeline should be shut off and emergency venting initiated. The design and operation of the circulation unit must be strictly controlled to ensure that the desorption outlet concentration is below 25% LEL and that the post-oxidation temperature does not exceed the design range, typically below 600℃, to avoid high-temperature deactivation of the oxidant.

[0060] Optionally, when the inlet VOCs concentration is <100 mg / m³ 3 At that time, the return air ratio should be set to 50%-70%;

[0061] When the inlet VOCs concentration is ≥100mg / m³ 3 At that time, the return air ratio should be set to 30%-50%.

[0062] Specifically, such as Figure 1 As shown, the mixed organic waste gas, after pretreatment by a multi-stage filtration unit, enters the adsorption zone of the zeolite rotor 2. The purified exhaust gas is directly discharged. The VOCs adsorbed by the rotor are effectively desorbed by hot air at approximately 200°C after being heated by heat exchanger 4. The desorbed high-concentration waste gas then passes through a gas diversion device, with a portion of the waste gas being transported to the waste gas inlet in a certain proportion. After being fully mixed with the original waste gas, it is adsorbed again by the rotor. Thus, this portion of the waste gas completes a dynamic cycle of adsorption and desorption. The other portion of the waste gas, after passing through the diversion device, enters the thermal oxidation unit to complete the subsequent thermal oxidation reaction, and the purified exhaust gas is discharged in compliance with standards.

[0063] The proportion of desorption recirculation air in the first pipeline is limited by various factors. This system is equipped with concentration detectors and temperature and pressure detectors to monitor and control the system in real time. While ensuring emissions meet standards, the system strives to achieve zero heat consumption. The desorption outlet concentration should be strictly controlled within 25% LEL, and the post-oxidation temperature should remain within the design range to ensure the safety and stability of each unit's operation. Specific implementation examples:

[0065] At 100,000m 3 / h, 200mg / m 3 Taking the exhaust gas condition as an example, the theoretical calculation of heat energy consumption for different energy-saving measures using the rotary turbine + CO process is shown in the table below.

[0066]

[0067]

[0068]

[0069] As can be seen from the table above, the energy-saving effect is significant after adopting the high-efficiency zeolite rotor + circulating adsorption-desorption process, which can theoretically save 11.9 Nm³. 3 / h. Based on 10 hours / day, 350 days / year, the unit price is 3.3 yuan / Nm. 3 Statistics show that it can save 137,400 yuan per year, accounting for about 30-40%, and the energy-saving effect is significant.

[0070] It is evident that existing technologies such as rotary wheel + CO / RTO / RCO adsorption concentration + thermal oxidation treatment generally suffer from high energy consumption. While these technologies achieve environmental compliance and create social value, they do not generate economic value for enterprises and instead become a burden, hindering their development. This invention employs a high-efficiency zeolite rotary wheel combined with a rotary wheel circulating adsorption-desorption process, operating in a near-zero heat consumption mode, thereby achieving energy conservation and reducing operating costs.

[0071] In summary, the circulating adsorption-desorption treatment system for low-concentration organic waste gas provided by this utility model adopts a high-efficiency zeolite rotor, overcoming the limitation of traditional rotors having a low concentration ratio (generally ≤20). This fundamentally solves the problem that the concentration of VOCs after concentration is not high enough to sustain the self-heating operation of thermal oxidation equipment such as CO furnaces. Simultaneously, a circulation unit is set up to adapt to different waste gas concentrations, adjusting in real time according to parameters such as concentration and temperature, ensuring safe and stable operation while achieving energy saving and consumption reduction, thus lowering operating costs. The high-efficiency zeolite rotor and high-efficiency heat exchanger are the basic conditions enabling this technology.

[0072] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A circulating adsorption-desorption treatment system for low-concentration organic waste gas, characterized in that, include: An adsorption concentration unit, comprising alternating adsorption and desorption zones, is used for the continuous adsorption and desorption of organic pollutants; A thermal desorption module is connected to the desorption zone and is equipped with a heating device to desorb the desorption zone; A gas diversion module is connected to the outlet end of the thermal desorption module and is configured with a first pipeline and a second pipeline with an adjustable gas output ratio. The first pipeline will partially remix the desorbed waste gas to the inlet of the adsorption zone. The thermal oxidation module is connected to the outlet end of the second pipeline and is used for thermal oxidation desorption of waste gas.

2. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in claim 1, characterized in that: The circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a heat exchanger; The thermal desorption module also includes a desorption duct for supplying air to the desorption zone; The thermal oxidation module also includes a heat exhaust duct; The desorption duct and the exhaust duct are respectively connected to the heat exchanger and exchange heat within the heat exchanger.

3. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in claim 2, characterized in that: The circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a preheater, which is installed on the second pipeline and is used to heat the high-concentration waste gas entering the thermal oxidation module from the second pipeline.

4. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in claim 3, characterized in that: The heat exchanger provides a heat source to the preheater.

5. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in any one of claims 1 to 4, characterized in that: The adsorption and concentration device is a zeolite rotor with a concentration ratio of 20 to 50 times.

6. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in any one of claims 1 to 4, characterized in that: The circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a multi-stage filter, which is installed at the air inlet of the adsorption zone.

7. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in any one of claims 1 to 4, characterized in that: The circulating adsorption-desorption treatment system for low-concentration organic waste gas also includes a safety control unit; the safety control unit includes: An online concentration detector is installed in the desorption outlet pipeline to monitor VOCs concentration in real time. The temperature and pressure monitoring unit monitors the inlet temperature of the adsorption zone, the temperature of the desorption zone, and the furnace temperature of the thermal oxidation module.

8. The circulating adsorption-desorption treatment system for low-concentration organic waste gas as described in claim 7, characterized in that: The safety control unit also includes an interlock controller, which automatically cuts off the return air pipeline and initiates emergency venting when the desorption outlet concentration is greater than a first preset value or the oxidation furnace temperature is greater than a second preset value.

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