A method and system for treating pharmaceutical waste salt smelt organic flue gas by using a near-oxygen cracking device

Abstract

The application discloses a method and system for treating medical waste salt smelting organic flue gas by using a near-oxygen cracking device. The system comprises a high-temperature molten salt tank, a quench tower, a fan, a graphite heat exchanger, a near-oxygen cracking reactor, a heat exchanger, a dust collector, a desulfurization tower, a denitration reactor and a tail gas circulation pipeline. The method comprises the following steps: preheating the catalyst in the reactor to 200-230 DEG C by hot air; mixing the molten flue gas after quenching with air, and mixing the preheating backflow with the tail gas according to the total gas volume ratio of 0.3-0.6, so that the temperature reaches the initial combustion temperature of the organic pollutants, and then the mixture enters the near-oxygen cracking reactor to perform a cracking-oxidation coupling reaction under the conditions of 0.1-0.3 MPa and 280-380 DEG C; and the obtained tail gas is partially recycled, and the remaining tail gas is discharged after being sequentially cooled by the heat exchanger, dust removal, desulfurization and denitration treatment.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment, specifically relating to a method and system for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-based pyrolysis device. Background Technology

[0002] Given the high content of organic pollutants and the complex types of waste salt in pharmaceutical waste, the removal of organic impurities needs to be a key focus. Currently, there are two main types of waste salt treatment and utilization technologies both domestically and internationally: harmlessness and resource recovery.

[0003] High-temperature melting treatment removes organic matter from molten industrial waste salt at temperatures of 800-1200 °C, achieving good removal efficiency. However, this method generally faces problems such as high energy consumption, equipment corrosion, and the generation of incineration flue gas containing harmful substances such as dioxins, leading to secondary pollution. This is especially true for pharmaceutical waste salt containing complex organic components, where flue gas treatment is more difficult and costly. Although some technologies, such as patent application CN109579025A, disclose "an efficient melting and incineration device for industrial waste salt," attempting to optimize incineration efficiency, incineration is essentially an end-of-pipe disposal technology that cannot achieve resource utilization of waste salt and is difficult to completely avoid secondary pollution. Taking flue gas treatment as an example, even after primary incineration, the emitted flue gas may still contain a large amount of recalcitrant macromolecular organic matter, such as halogenated hydrocarbons, benzene compounds, and polycyclic aromatic hydrocarbons. To effectively remove these organic matter, a large amount of auxiliary fuel is usually consumed for secondary combustion in the secondary combustion chamber unit. This process not only further increases energy consumption, but the exhaust gas after secondary combustion may still contain dioxins, further exacerbating secondary pollution. Therefore, the industry urgently needs to develop a new method that can replace the traditional two-combustion chamber and achieve low-temperature and efficient degradation of macromolecular organic compounds. Summary of the Invention

[0004] This invention provides a method and system for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-induced pyrolysis device. This method replaces the traditional high-temperature incineration process with oxygen-induced catalytic pyrolysis-oxidation coupling technology. Through medium- and low-temperature reaction conditions, it achieves efficient degradation and complete removal of macromolecular organic matter in the incineration flue gas. Combined with a tail gas recycling and waste heat utilization process, it significantly reduces the overall energy consumption of the system while effectively inhibiting the formation of harmful byproducts such as dioxins. It has significant advantages in terms of high energy efficiency, stable operation, and environmental friendliness.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A system for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-induced pyrolysis device includes: a high-temperature molten salt tank, a quench tower, a fan, a graphite heat exchanger, an oxygen-induced pyrolysis reactor, a heat exchanger, a dust collector, a desulfurization tower, a denitrification reactor, a flue gas feed pipe, an air feed pipe, and a tail gas circulation pipe.

[0007] Pharmaceutical waste salt is melted in a high-temperature molten salt tank. The high-temperature organic flue gas generated during the melting process is fed into a quench tower for rapid cooling. The cooled flue gas is introduced by a fan and mixed with air introduced through an air feed pipe to obtain initial mixed flue gas. The initial mixed flue gas is mixed and preheated with part of the high-temperature tail gas discharged from the oxygen-induced cracking reactor, and then heated and regulated by a graphite heat exchanger so that the temperature of the mixed flue gas to be reacted entering the oxygen-induced cracking reactor reaches the initial combustion temperature of organic pollutants. The mixed flue gas to be reacted is then fed into the oxygen-induced cracking reactor filled with catalyst to carry out a cracking-oxidation coupling reaction to obtain high-temperature tail gas.

[0008] Except for a portion that is returned through the exhaust gas circulation pipeline, the remaining portion of the high-temperature exhaust gas is cooled in a heat exchanger and then sequentially enters a dust collector, a desulfurization tower, and a denitrification reactor for purification. The purified exhaust gas is then discharged through a chimney.

[0009] A method for treating molten waste gas from pharmaceutical waste salt using an oxygen-based pyrolysis device includes the following specific steps:

[0010] (1) Preheating: Hot air is used to preheat the catalyst in the oxygen cracking reactor to bring it to the catalytic activity temperature;

[0011] (2) Waste gas pretreatment and catalytic reaction: In this invention, the high-temperature organic flue gas generated during the melting process of pharmaceutical waste salt is introduced into a quench tower for rapid cooling to a temperature range suitable for subsequent treatment. The cooled flue gas is mixed with air in a certain proportion to form an initial mixed flue gas. This initial mixed flue gas is mixed and preheated with a portion of the high-temperature tail gas from the outlet of the oxygen-containing pyrolysis reactor. The heat carried by the high-temperature tail gas is used to heat it to above the initial combustion temperature of organic pollutants, resulting in a mixed flue gas with a suitable temperature for reaction. Then, the preheated mixed flue gas is passed into the oxygen-containing pyrolysis reactor with a preheated catalyst. Under the action of the catalyst, a pyrolysis-oxidation coupling reaction is carried out, which degrades large molecular organic matter into small molecular substances and further oxidizes them. After the reaction is completed, high-temperature tail gas is obtained.

[0012] (3) High-temperature exhaust gas recovery and purification: The high-temperature exhaust gas is divided into two paths. One part is returned to the system as reflux high-temperature exhaust gas to preheat the initial mixed flue gas, realizing the internal circulation utilization of the reaction waste heat; the remaining part enters the heat exchanger for cooling to obtain low-temperature purified gas. Finally, the low-temperature purified gas is passed through a dust removal device, a desulfurization system, and a selective catalytic reduction denitrification reactor for staged deep purification to ensure that all pollutants meet the emission standards before being discharged through the chimney.

[0013] Furthermore, in step (1), the temperature of the hot air used to preheat the catalyst is 350~500 ℃; the catalyst required for the oxygen cracking reaction is preheated to 200~230 ℃.

[0014] Furthermore, in step (1), the catalyst uses one or two of TiO2, Al2O3, ZSM-5 molecular sieve, MCM-41 molecular sieve, and MCM-42 molecular sieve as a support, and one or more of transition metal oxides such as titanium oxide, chromium oxide, vanadium oxide, cerium oxide, manganese oxide, and / or noble metal Pt as active components. The loading of the active components is 0.5% to 20%, and the catalyst particle size is 2 to 4 mm.

[0015] Furthermore, in step (2), the concentration of organic matter in the molten organic flue gas from the pharmaceutical waste salt is 7000~11500 mg / Nm³. 3 The organic compounds in the molten organic flue gas from the pharmaceutical waste salt are selected from one or more of halogenated hydrocarbons such as chlorobenzene, dichloromethane, and trichloroethylene, as well as benzene series compounds.

[0016] The initial mixed flue gas formed by mixing the organic flue gas with air is measured according to the total space velocity in the oxygen-containing pyrolysis reactor, wherein the feed rate of the organic flue gas is 10~200 m. 3 / (kg cat •h), the air feed rate is 1~50 m 3 / (kg cat ·h).

[0017] Furthermore, in step (2), the absolute pressure of the oxygen pyrolysis reaction is 0.1~0.3 MPa, and the reaction temperature is 280~380 ℃. The high-temperature exhaust gas discharged after the reaction has a temperature of 250~450 ℃ and an organic matter content of 20~50 mg / Nm³. 3 .

[0018] Furthermore, in step (2), the volume ratio of the high-temperature tail gas reflux flow rate at the outlet of the oxygen-induced cracking reactor to the total gas volume at the outlet of the oxygen-induced cracking reactor is 0.3~0.6. After the high-temperature tail gas is refluxed to the blower inlet and mixed with the subsequently introduced initial mixed flue gas, the concentration of organic matter in the obtained mixed flue gas to be reacted is diluted and adjusted to a range suitable for catalytic reaction. The temperature of the mixed flue gas to be reacted obtained by mixing the high-temperature tail gas with the subsequently introduced initial mixed flue gas is 200~225 ℃.

[0019] Furthermore, in step (3), the temperature of the low-temperature purified gas obtained after heat exchange cooling is 180~250 ℃, and then it enters the subsequent system for processing.

[0020] The second objective of this invention is to provide a system for treating molten organic fumes from pharmaceutical waste salt using an oxygen-induced pyrolysis device. The system includes: a high-temperature molten salt tank, a quench tower, a fan, a graphite heat exchanger, an oxygen-induced pyrolysis reactor, a heat exchanger, and a dust collector. The graphite heat exchanger includes a shell side and a tube side. The fan has a mixed gas inlet on one side and a mixed gas outlet on the other side.

[0021] The system for melting organic fumes from pharmaceutical waste salts also includes a flue gas inlet pipe and an air inlet pipe. A mixed gas inlet on the blower connects to both the flue gas inlet pipe and the air inlet pipe. The flue gas and air are mixed by the blower. The mixed gas outlet on the blower is connected to the shell-side inlet of a graphite heat exchanger. The tube side of the graphite heat exchanger has a steam inlet and a steam outlet, through which steam is introduced to heat the mixed gas. The shell-side outlet of the graphite heat exchanger is connected to the inlet of an oxygen-fired pyrolysis reactor, and the outlet of the oxygen-fired pyrolysis reactor is connected to the heat exchanger... The heat exchanger is connected to the hot-side inlet, the hot-side outlet is connected to the dust collector inlet, the dust collector outlet is connected to the desulfurization tower inlet, the desulfurization tower outlet is connected to the denitrification reactor inlet, and the denitrification reactor outlet is connected to the chimney. A tail gas circulation pipeline is also provided, with one end connected to the high-temperature tail gas pipeline between the outlet of the oxygen-induced cracking reactor and the hot-side inlet of the heat exchanger, and the other end connected to the pipeline between the outlet of the quench tower and the mixed gas inlet of the blower. Preferably, a first control valve is installed on the flue gas feed pipeline, a second control valve is installed on the air feed pipeline, and a third control valve is installed on the tail gas circulation pipeline.

[0022] The beneficial effects of this invention are:

[0023] This invention replaces the traditional secondary combustion chamber with an oxygen-based pyrolysis device, significantly reducing the degradation temperature of organic matter in the combustion flue gas from 800~1200 ℃ in the traditional incineration process to a medium-low temperature range of 280~380 ℃. While achieving efficient removal of large molecular organic matter, it significantly reduces the system's heating energy consumption and operating costs.

[0024] This invention targets typical recalcitrant organic compounds such as chlorobenzene, dichloromethane, trichloroethylene, and benzene series compounds in the molten organic flue gas from pharmaceutical waste salt, with a treatment concentration of 7000~11500 mg / Nm³. 3 When dealing with high-concentration waste gas, the system can achieve stable and efficient purification. Verification through examples shows that the system exhibits superior adaptability to both single and mixed pollutants, with organic matter removal rates exceeding 99.5%.

[0025] This invention maintains the stability of the reaction system when there are fluctuations in waste gas concentration or composition by adjusting key parameters such as recirculated gas volume, inlet space velocity, and reaction temperature. In particular, through catalyst optimization, this process can achieve efficient degradation in a lower temperature range, further highlighting its energy-saving potential and operational flexibility.

[0026] This invention achieves effective utilization of waste heat during the reaction process through internal recirculation of exhaust gas. While improving energy utilization, the system operates under medium and low temperature conditions, effectively inhibiting the formation of highly toxic byproducts such as dioxins and reducing the risk of secondary pollution.

[0027] The flue gas treated by this invention undergoes further purification through multiple stages, including dust removal, desulfurization, and denitrification. The final emission gas contains all pollutants that meet the requirements of the "Integrated Emission Standard of Air Pollutants" (GB16297-1996) and relevant local emission standards, allowing for direct emission compliance and demonstrating significant environmental friendliness. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the system of the present invention that uses an oxygen-based pyrolysis device to treat the molten organic flue gas from pharmaceutical waste salt;

[0029] Figure 1 In the diagram, 1 is a high-temperature molten salt tank, 2 is a quench tower, 3 is a fan, 4 is a graphite heat exchanger, 5 is an oxygen cracking reactor, 6 is a heat exchanger, 7 is a dust collector, 8 is a desulfurization tower, and 9 is a denitrification reactor. Detailed Implementation

[0030] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0031] Example 1

[0032] like Figure 1As shown, a system for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-induced pyrolysis device includes: a high-temperature molten salt tank 1, a quench tower 2, a fan 3, a graphite heat exchanger 4, an oxygen-induced pyrolysis reactor 5, a heat exchanger 6, a dust collector 7, a desulfurization tower 8, a denitrification reactor 9, a flue gas feed pipe, an air feed pipe and a tail gas circulation pipe, a first control valve, a second control valve, and a third control valve; the high-temperature organic flue gas outlet of the high-temperature molten salt tank 1 is connected to the air inlet of the quench tower 2, the mixed gas inlet of the fan 3 is connected to both the flue gas feed pipe and the air feed pipe, and the air inlet of the flue gas feed pipe is connected to the air outlet of the quench tower 2; the graphite heat exchanger 4 includes a shell... The mixed gas outlet of the blower 3 is connected to the shell-side inlet of the graphite heat exchanger 4. The tube-side of the graphite heat exchanger 4 is equipped with a steam inlet and a steam outlet. The shell-side outlet of the graphite heat exchanger 4 is connected to the inlet of the oxygen-induced cracking reactor 5. The outlet of the oxygen-induced cracking reactor 5 is connected to the hot-side inlet of the heat exchanger 6 via a high-temperature tail gas pipeline and to the mixed gas inlet of the blower 3 via a tail gas circulation pipeline. The hot-side outlet of the heat exchanger 6 is connected to the inlet of the dust collector 7. The outlet of the dust collector 7 is connected to the inlet of the desulfurization tower 8. The outlet of the desulfurization tower 8 is connected to the inlet of the denitrification reactor 9. The outlet of the denitrification reactor 9 is connected to the chimney.

[0033] A first control valve is installed on the connecting pipe between the high-temperature organic flue gas outlet and the quench tower, a second control valve is installed on the air feed pipe, and a third control valve is installed on the tail gas circulation pipe.

[0034] The heat exchanger 6 is a water-cooled heat exchanger.

[0035] Based on the system of this embodiment that uses an oxygen-based pyrolysis device to treat the organic flue gas from the melting of pharmaceutical waste salt, chlorobenzene was selected as a representative pollutant of typical halogenated aromatic hydrocarbons in the organic flue gas from the melting of pharmaceutical waste salt. The initial concentration of chlorobenzene in the organic flue gas was 8500 mg / Nm³. 3 The temperature is approximately 850℃.

[0036] In this embodiment, the oxygen-containing cracking reactor is loaded with a supported transition metal oxide catalyst. The catalyst is prepared using TiO2 as a support via an excess impregnation method: the TiO2 support is impregnated in a mixed aqueous solution containing ammonium metavanadate and chromium nitrate, with a total concentration of 15% for the active component precursors (ammonium metavanadate and chromium nitrate), and a mass ratio of V2O5 to Cr2O3 of 7:3 based on the final oxides; after impregnation for 12 hours, it is dried at 120°C for 4 hours, and then calcined at 500°C for 4 hours in air atmosphere to obtain a catalyst with a V2O5 loading of 7% and a Cr2O3 loading of 3%, and a catalyst particle size of 2-4 mm.

[0037] Tests showed that the oxygen volume content in the mixed flue gas at the reactor inlet was 5.2%, which met the oxidation atmosphere required for oxygen cracking, ensuring deep oxidation of organic matter while avoiding heat loss caused by excessive air.

[0038] The specific implementation steps are as follows:

[0039] (1) The high-temperature organic flue gas (with an initial chlorobenzene concentration of 8500 mg / Nm³) generated by melting in a high-temperature molten salt tank 3 The flue gas (at a temperature of 850℃) is drawn from the flue gas and fed into the quench tower through a flue gas duct. In the quench tower, softened water is used as the cooling medium. It is atomized through high-pressure atomizing nozzles and then comes into direct contact with the high-temperature organic flue gas for rapid cooling. The softened water flow rate is controlled at 120 kg / h, calculated based on the flue gas inlet temperature (850℃) and the required cooling range (to 180℃), ensuring that the flue gas residence time in the quench tower is less than 1 second, quickly passing through the dioxin resynthesis temperature window. After quenching, the flue gas temperature drops to 180℃ and enters the subsequent treatment unit.

[0040] (2) The rapidly cooled flue gas is mixed with air using a fan, and the total flow rate of the mixed gas is controlled to be 1200 m³ / s. 3 / h, where the air flow rate is 200 m³ / h. 3 / h, to obtain the initial mixed flue gas.

[0041] (3) The above initial mixed flue gas is mixed and preheated with a portion of the high-temperature circulating gas from the outlet of the oxygen-containing cracking reactor, and then introduced into the shell side of the graphite heat exchanger. Saturated steam at 0.6 MPa (gauge pressure) and 165°C is introduced into the tube side of the graphite heat exchanger as a heat source to heat the mixed gas to 215°C, thus obtaining the mixed flue gas to be reacted.

[0042] (4) The mixed flue gas to be reacted is introduced into the oxygen-containing cracking reactor, and the feed rate of chlorobenzene is controlled at 50 m. 3 / (kg cat The air feed rate is 10 m / h. 3 / (kg cat The catalyst loading was 20.0 kg, the absolute reaction pressure was 0.1 MPa, and the temperature of the catalytic bed in the reactor was maintained at 380 °C. Chlorobenzene underwent a cracking-oxidation coupled reaction under the action of the catalyst.

[0043] (5) A portion of the high-temperature flue gas (temperature 395℃, chlorobenzene concentration below 20 mg / Nm³, removal rate above 99.7%) from the outlet of the oxygen-induced cracking reactor is recycled as circulating gas and mixed with the initial mixed flue gas for preheating. By controlling the third control valve, the volume ratio of the circulating gas to the total gas volume at the outlet of the oxygen-induced cracking reactor is 0.5. The remaining high-temperature flue gas is discharged as purified gas. This purified gas is passed into heat exchanger 6 for heat recovery and cooling to 190℃.

[0044] (6) The cooled exhaust gas enters the subsequent purification unit for treatment. The baghouse dust collector uses pulse-jet cleaning, with PTFE-coated filter bags and a filtration velocity controlled at 0.8 m / min to ensure the outlet dust concentration is below 10 mg / Nm³. The gas after dust removal enters the alkaline spray desulfurization tower, employing a double-layer spray structure with 5 wt% NaOH solution as the absorbent and a liquid-to-gas ratio controlled at 3 L / m³ to ensure the outlet acid gas (HCl) concentration is below 2 mg / Nm³. The desulfurized gas then enters the denitrification reactor, where a selective catalytic reduction process is used, filled with a honeycomb vanadium-titanium catalyst. The reaction temperature is controlled at 180–220℃, matching the heat exchanger outlet gas temperature (190℃), with an ammonia-to-nitrogen molar ratio of 1:1 to ensure the outlet NOx concentration is below 50 mg / Nm³. The purified gas is finally discharged through the chimney in compliance with standards. Testing showed that the final emission gas concentration of chlorobenzene was below 20 mg / Nm³, with a removal rate exceeding 99.7%. The detection process is as follows: During stable system operation, sampling points were set up at the chimney emission outlet, and the concentration of chlorobenzene in the emission gas was periodically detected using gas chromatography-mass spectrometry (GC-MS, equipped with a flame ionization detector FID). Sampling frequency was three times daily, with each sample volume being 10 L. The detection method followed the "Determination of Chlorobenzene Compounds in Exhaust Gas from Stationary Sources by Gas Chromatography" (HJ / T 66-2001). Hydrogen chloride concentration was determined using ion chromatography, following the "Determination of Hydrogen Chloride in Exhaust Gas from Stationary Sources by Ion Chromatography" (HJ 549-2016). This embodiment demonstrates the highly efficient removal capability of the described process from typical macromolecular organic compounds in the molten waste gas of pharmaceutical waste salt at significantly lower temperatures, and the effective utilization of reaction heat is achieved through tail gas internal recirculation. To verify the long-term operational stability of the system, it was operated continuously for six months under the aforementioned process conditions. During this period, the operating parameters remained constant, including a total gas throughput of 1200 m³ / h, an air flow rate of 200 m³ / h, a recirculation ratio of 0.5, a reactor inlet temperature of 215℃, a reaction temperature of 380℃, a reaction pressure of 0.1 MPa, and a catalyst loading of 20.0 kg. The concentration of chlorobenzene in the exhaust gas was sampled and tested monthly. After six months of continuous operation, the chlorobenzene removal rate consistently remained above 99.68%, the system operated stably, no significant decrease in catalyst activity was observed, and no abnormal phenomena such as corrosion or blockage were observed in the equipment. This verifies the long-term operational reliability and industrial application potential of the process described in this invention.

[0045] Example 2

[0046] This embodiment adopts Figure 1The process flow shown selects dichloromethane as a representative pollutant of typical halogenated aliphatic hydrocarbons in the organic flue gas from pharmaceutical waste salt melting, to verify the treatment effect of this invention on chlorinated aliphatic hydrocarbons. In this embodiment, the representative organic pollutant in the treated organic flue gas is dichloromethane, with an initial concentration of 11500 mg / Nm³. 3 .

[0047] In this embodiment, the catalyst loaded in the oxygen pyrolysis reactor is supported by Al2O3 and the active component is Cr2O3. It is prepared by impregnation method (preparation conditions are the same as in Example 1), with a Cr2O3 loading of 8% and a catalyst particle size of 2-4 mm.

[0048] Tests showed that the oxygen volume content in the mixed flue gas at the reactor inlet was 4.8%, which meets the oxidizing atmosphere required for oxygen cracking.

[0049] The specific implementation steps are as follows: (1) Same as step (1) in Example 1, the high-temperature organic flue gas is passed into the quench tower for rapid cooling to below 180°C. (2) The low-temperature flue gas after rapid cooling is mixed with air by a fan, and the total gas volume is 1050 m³. 3 / h, of which the air flow rate is 95 m³ / h 3 / h, to obtain initial mixed flue gas. (3) Mix and preheat the initial mixed flue gas with a portion of the high-temperature circulating gas from the outlet of the oxygen-containing cracking reactor, and control the circulation ratio (the volume ratio of circulating gas to the total gas volume at the reactor outlet) to be 0.5. The mixed gas is then introduced into a graphite heat exchanger, and 0.6 MPa (gauge pressure) saturated steam is introduced into the tube side to heat it to 205°C before it enters the oxygen-containing cracking reactor. (4) The preheated mixed flue gas to be reacted is introduced into the oxygen-containing cracking reactor, and the cracking-oxidation coupling reaction is carried out under the action of a catalyst. The dichloromethane feed rate is controlled to be 59 m 3 / (kg cat •h), the air feed rate is 5.9 m 3 / (kg cat (5) After the reaction is completed, the high-temperature purified gas is discharged. A portion of it is recycled as circulating gas according to step (3), and the remaining high-temperature purified gas is discharged at a temperature of 365°C. The gas is then passed through a heat exchanger to cool to 185°C. (6) After cooling, the gas is processed sequentially through a bag filter, an alkaline spray desulfurization tower, and a denitrification reactor according to the purification process described in step (6) of Example 1 before being discharged in compliance with emission standards.

[0050] Tests showed that the concentration of dichloromethane in the final emitted gas was below 50 mg / Nm³. 3The removal rate was higher than 99.5%. The detection method was the same as in Example 1. To verify the long-term operational stability of the system, it was continuously operated for six months under the above process conditions. During the operation, the operating parameters were kept constant, and the dichloromethane removal rate remained above 99.45%. The system operated stably, and the catalyst activity did not show a significant decrease, thus verifying the long-term and efficient treatment capability of the process of this invention for chlorinated aliphatic hydrocarbons.

[0051] Example 3

[0052] This embodiment adopts Figure 1 The process flow shown selects trichloroethylene as a representative unsaturated chlorinated hydrocarbon pollutant in the organic flue gas from pharmaceutical waste salt melting to verify the degradation effect of this invention on unsaturated chlorinated hydrocarbons. In this embodiment, the representative organic pollutant in the treated organic flue gas is trichloroethylene, with an initial concentration of 9800 mg / Nm³. 3 .

[0053] In this embodiment, the catalyst packed in the oxygen pyrolysis reactor is supported by ZSM-5 molecular sieve, with CeO2 as the active component. It is prepared by impregnation method (preparation conditions are the same as in Example 1), with a CeO2 loading of 10% and a catalyst particle size of 2-4 mm.

[0054] Tests showed that the oxygen volume content in the mixed flue gas at the reactor inlet was 5.6%, which meets the oxidizing atmosphere required for oxygen cracking.

[0055] The specific implementation steps are as follows: (1) Same as step (1) in Example 1, the high-temperature organic flue gas is passed into the quench tower for rapid cooling to below 180°C. (2) The low-temperature flue gas after rapid cooling is mixed with air by a fan, and the total gas volume is 1150 m³. 3 / h, of which the airflow rate is 172.5 m³ / h. 3 / h, to obtain initial mixed flue gas. (3) Mix and preheat the initial mixed flue gas with part of the high-temperature circulating gas from the outlet of the oxygen-induced cracking reactor, and control the circulation ratio to 0.5. After mixing, the gas is introduced into a graphite heat exchanger, and 0.6 MPa (gauge pressure) saturated steam is introduced into the tube side to heat it to 225°C before entering the oxygen-induced cracking reactor. (4) The preheated mixed flue gas to be reacted is introduced into the oxygen-induced cracking reactor, and the cracking-oxidation coupling reaction is carried out under the action of the catalyst. The trichloroethylene feed rate is controlled to be 70 m 3 / (kg cat •h), the air feed rate is 12.3 m 3 / (kg cat(h), the catalyst loading is 14.0 kg, the absolute reaction pressure is 0.1 MPa, and the temperature inside the reactor is maintained at 320℃. (5) After the reaction is completed, the high-temperature purified gas is discharged, part of which is recycled as circulating gas according to step (3), and the remaining high-temperature purified gas is discharged at a temperature of 340℃. The gas is passed into a heat exchanger and cooled to 195℃. (6) After cooling, the gas is treated according to the purification process described in step (6) of Example 1 and discharged in compliance with standards.

[0056] Tests showed that the concentration of trichloroethylene in the final emitted gas was below 25 mg / Nm³. 3 The removal rate was higher than 99.7%. The detection method was the same as in Example 1. To verify the long-term operational stability of the system, it was continuously operated for six months under the above process conditions. During the operation, the operating parameters were kept constant, and the trichloroethylene removal rate remained above 99.65%. The system operated stably, and the catalyst activity did not show a significant decrease. This verified the excellent treatment effect of the process of the present invention on unsaturated chlorinated hydrocarbons and the applicability of the molecular sieve supported catalyst.

[0057] Example 4:

[0058] This embodiment adopts Figure 1 The process flow shown is used to verify the comprehensive treatment capability of this invention for high-concentration, multi-component complex waste gases. The organic flue gas treated in this embodiment also contains chlorobenzene (6000 mg / Nm³). 3 ) and dichloromethane (5000 mg / Nm 3 The total organic matter concentration was 11000 mg / Nm³. 3 .

[0059] In this embodiment, the catalyst packed in the oxygen pyrolysis reactor uses TiO2 as a support and Cr2O3 and MnO2 as composite active components. It is prepared by co-impregnation method (preparation conditions are the same as in Example 1). The loading of Cr2O3 is 5%, the loading of MnO2 is 5%, and the catalyst particle size is 2-4 mm.

[0060] Tests showed that the oxygen volume content in the mixed flue gas at the reactor inlet was 6.0%, which meets the oxidizing atmosphere required for oxygen cracking.

[0061] The specific implementation steps are as follows: (1) Same as step (1) in Example 1, the high-temperature organic flue gas is passed into the quench tower for rapid cooling to below 180°C. (2) The low-temperature flue gas after rapid cooling is mixed with air by a fan, and the total gas volume is 1250 m³. 3 / h, where the air flow rate is 225 m³ / h. 3 / h, to obtain initial mixed flue gas. (3) Mix and preheat the initial mixed flue gas with a portion of the high-temperature circulating gas from the outlet of the oxygen-induced cracking reactor, and control the circulation ratio to 0.5. After mixing, the gas is introduced into a graphite heat exchanger, and 0.6 MPa (gauge pressure) saturated steam is introduced into the tube side to heat it to 218°C before entering the oxygen-induced cracking reactor. (4) The preheated mixed flue gas to be reacted is introduced into the oxygen-induced cracking reactor, and the cracking-oxidation coupling reaction is carried out under the action of the catalyst. The total organic matter feed rate is controlled to be 77 m 3 / (kg cat ·h), air feed rate is 17 m 3 / (kg cat (5) After the reaction is completed, the high-temperature purified gas is discharged. A portion of it is recycled as circulating gas according to step (3), and the remaining high-temperature purified gas is discharged at a temperature of 385°C. The gas is then passed through a heat exchanger to cool to 195°C. (6) After cooling, the gas is treated according to the purification process described in step (6) of Example 1 and discharged in compliance with standards.

[0062] Tests showed that the concentration of chlorobenzene in the final emitted gas was below 15 mg / Nm³. 3 Dichloromethane concentration below 40 mg / Nm 3 The total removal rate was higher than 99.6%. The detection method was the same as in Example 1. To verify the long-term operational stability of the system, it was continuously operated for six months under the above process conditions. During the operation, the operating parameters were kept constant, and the total removal rate remained above 99.55%. The system operated stably, and the catalyst activity did not show a significant decrease. This verified the comprehensive purification performance of the process of this invention for complex mixed waste gas and the synergistic effect of the composite active components.

[0063] Example 5:

[0064] This embodiment adopts Figure 1 The process flow shown demonstrates the potential of this invention to achieve high efficiency at lower reaction temperatures by optimizing the catalyst, further highlighting its energy-saving advantages. In this embodiment, the representative organic pollutant in the treated flue gas is chlorobenzene, with an initial concentration of 7000 mg / Nm³. 3 .

[0065] In this embodiment, the catalyst packed in the oxygen pyrolysis reactor is supported by TiO2 and loaded with highly dispersed Pt as the active component. It is prepared by impregnation method (the preparation conditions are the same as in Example 1, but the calcination temperature is adjusted to 450℃). The Pt loading is 0.5%, and the catalyst particle size is 2-4 mm.

[0066] Tests showed that the oxygen volume content in the mixed flue gas at the reactor inlet was 5.7%, which meets the oxidizing atmosphere required for oxygen cracking.

[0067] The specific implementation steps are as follows: (1) Same as step (1) in Example 1, the high-temperature organic flue gas is passed into the quench tower for rapid cooling to below 180°C. (2) The low-temperature flue gas after rapid cooling is mixed with air by a fan, and the total gas volume is 1150 m³. 3 / h, of which the air flow rate is 196 m³ / h. 3 / h, to obtain initial mixed flue gas. (3) Mix and preheat the initial mixed flue gas with part of the high-temperature circulating gas from the outlet of the oxygen-containing cracking reactor, and control the circulation ratio to 0.5. After mixing, the gas is introduced into a graphite heat exchanger, and 0.6 MPa (gauge pressure) saturated steam is introduced into the tube side to heat it to 200°C before entering the oxygen-containing cracking reactor. (4) The preheated mixed flue gas to be reacted is introduced into the oxygen-containing cracking reactor, and the cracking-oxidation coupling reaction is carried out under the action of the catalyst. The chlorobenzene feed rate is controlled to be 54.5 m 3 / (kg cat •h), the air feed rate is 11.2 m 3 / (kg cat (h), the catalyst loading is 17.5 kg, the absolute reaction pressure is 0.1 MPa, and the temperature inside the reactor is maintained at 280℃. (5) After the reaction is completed, the high-temperature purified gas is discharged, part of which is recycled as circulating gas according to step (3), and the remaining high-temperature purified gas is discharged at a temperature of 295℃. The gas is passed into a heat exchanger and cooled to 185℃. (6) After cooling, the gas is treated according to the purification process described in step (6) of Example 1 and discharged in compliance with standards.

[0068] Tests showed that the concentration of chlorobenzene in the final emitted gas was below 20 mg / Nm³. 3 The removal rate was higher than 99.5%. The detection method was the same as in Example 1. To verify the long-term operational stability of the system, it was continuously operated for six months under the above process conditions. During the operation, the operating parameters were kept constant, and the chlorobenzene removal rate remained above 99.45%. The system operated stably, and no significant decrease in catalyst activity was observed. This example shows that, through catalyst optimization, the process of the present invention can achieve efficient operation in a low-temperature range of 280℃, with a reaction temperature 100℃ lower than that of Example 1, demonstrating significant energy-saving potential and good operational stability.

[0069] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A system for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-based pyrolysis device, characterized in that, include: High-temperature molten salt tank, quench tower, fan, graphite heat exchanger, oxygen-induced cracking reactor, heat exchanger, dust collector, desulfurization tower, denitrification reactor, flue gas feed pipeline, air feed pipeline and tail gas circulation pipeline; The high-temperature organic flue gas outlet of the high-temperature molten salt tank is connected to the air inlet of the quench tower. The mixed gas inlet of the blower is connected to the flue gas feed pipe and the air feed pipe respectively. The air inlet end of the flue gas feed pipe is connected to the air outlet of the quench tower. The graphite heat exchanger includes a shell side and a tube side. The mixed gas outlet of the blower is connected to the shell side inlet of the graphite heat exchanger. The shell side outlet of the graphite heat exchanger is connected to the air inlet of the oxygen-induced cracking reactor. The tube side of the graphite heat exchanger is provided with a steam inlet and a steam outlet. The air outlet of the oxygen-induced cracking reactor is connected to the hot side inlet of the heat exchanger via a high-temperature tail gas pipeline and to the mixed gas inlet of the blower via a tail gas circulation pipeline. The hot side outlet of the heat exchanger is connected to the air inlet of the dust collector. The air outlet of the dust collector is connected to the air inlet of the desulfurization tower. The air outlet of the desulfurization tower is connected to the air inlet of the denitrification reactor. The air outlet of the denitrification reactor is connected to the chimney. A tail gas circulation pipeline is also provided.

2. The system according to claim 1, characterized in that, A first control valve is installed on the connecting pipe between the high-temperature organic flue gas outlet and the quench tower, a second control valve is installed on the air feed pipe, and a third control valve is installed on the tail gas circulation pipe.

3. A method for treating molten organic flue gas from pharmaceutical waste salt using an oxygen-based pyrolysis device, characterized in that, include: Pharmaceutical waste salt is fed into a high-temperature molten salt tank and melted at 800–1200°C. During the melting process, the pharmaceutical waste salt releases high-temperature organic flue gas containing macromolecular organic matter. This high-temperature organic flue gas is drawn out from the high-temperature molten salt tank and fed into a quench tower for rapid cooling. The quenched flue gas is then introduced by a fan and mixed with air introduced through an air feed pipe to obtain initial mixed flue gas. The initial mixed flue gas is mixed and preheated with a portion of the high-temperature tail gas discharged from the oxygen-induced cracking reactor, and then heated and regulated by a graphite heat exchanger so that the temperature of the mixed flue gas to be reacted entering the oxygen-induced cracking reactor reaches the initial combustion temperature of the organic pollutants. The mixed flue gas to be reacted is then fed into the oxygen-induced cracking reactor filled with catalyst to carry out a cracking-oxidation coupled reaction to obtain high-temperature tail gas. Except for a portion that is returned through the exhaust gas circulation pipeline, the remaining portion of the high-temperature exhaust gas is cooled in a heat exchanger and then sequentially enters a dust collector, a desulfurization tower, and a denitrification reactor for purification. The purified exhaust gas is then discharged through a chimney.

4. The method according to claim 3, characterized in that, The catalyst packed in the oxygen pyrolysis reactor is preheated with hot air at a temperature of 350-500°C, and the catalyst is preheated to 200-230°C.

5. The method according to claim 3, characterized in that, The oxygen-containing cracking reactor is filled with a catalyst, which uses one or two of TiO2, Al2O3, ZSM-5 molecular sieve, MCM-41 molecular sieve, and MCM-42 molecular sieve as a support, and one or more of transition metal oxides and / or noble metals as active components; the transition metal oxides are selected from titanium oxide, chromium oxide, vanadium oxide, cerium oxide, and manganese oxide; the noble metal is Pt; the loading of the active component is 0.5% to 20%; and the catalyst particle size is 2 to 4 mm.

6. The method according to claim 3, characterized in that, The concentration of organic matter in the molten organic flue gas from the pharmaceutical waste salt is 7000~11500 mg / Nm³. 3 The initial mixed flue gas formed by mixing the organic flue gas with air is measured according to the total space velocity in the oxygen-containing pyrolysis reactor, wherein the feed rate of the organic flue gas is 10~200 m. 3 / (kg cat The air feed velocity is 1~50 m / h. 3 / (kg cat The amount of catalyst loaded is determined based on the feed rate of the organic pollutants.

7. The method according to claim 3, characterized in that, The absolute pressure of the pyrolysis-oxidation coupling reaction is 0.1~0.3 MPa, and the reaction temperature is 280~380 ℃; the temperature of the high-temperature tail gas discharged after the reaction is 250~450 ℃, and the organic matter content is 20~50 mg / Nm³; the temperature of the low-temperature purified gas obtained after cooling by the heat exchanger is 180~250 ℃.

8. The method according to claim 3, characterized in that, The volume ratio of the high-temperature tail gas recirculation flow rate at the outlet of the oxygen-induced pyrolysis reactor to the total gas volume at the outlet of the oxygen-induced pyrolysis reactor is 0.3 to 0.

6.

9. The method according to claim 8, characterized in that, The high-temperature exhaust gas is returned to the fan inlet and mixed with the initial mixed flue gas to obtain a mixed flue gas with a temperature of 200~225 ℃.

10. The method according to claim 3, characterized in that, The quench tower rapidly cools the high-temperature organic flue gas by directly contacting the atomized cooling medium with the gas, thereby reducing the temperature of the high-temperature organic flue gas to below 180°C.

Images