Gas on-line detection device based on formaldehyde reaction system

Abstract

The utility model relates to a gas on -line detection technical field is a kind of gas on -line detection device based on formaldehyde reaction system, it includes gas mixer, booster device, methanol vaporizer, formaldehyde reactor, water tank, gas analyzer, there is mixed gas pipeline communication between gas mixer and methanol vaporizer, there is methanol vaporization gas pipeline communication between methanol vaporizer and formaldehyde reactor, there is first formaldehyde gas pipeline communication between formaldehyde reactor and methanol vaporizer, there is first bypass pipeline communication between mixed gas pipeline and water tank, there is gas return pipeline communication between water tank and mixed gas pipeline, gas analyzer is installed on gas return pipeline.The utility model structure is reasonable and compact, convenient to use, it adopts closed cycle gas on -line detection mode, guarantees the continuity and accuracy of detection data, also avoid the environmental pollution problem caused by gas loss, provide safe and reliable technical support for formaldehyde production process.

Description

Technical Field

[0001] This utility model relates to the field of online gas detection technology, and is an online gas detection device based on a formaldehyde reaction system. Background Technology

[0002] Formaldehyde is an important chemical raw material used in the production of phenolic resins, urea-formaldehyde resins, dyes, and pharmaceuticals. Industrially, formaldehyde is produced on a large scale through catalytic oxidation.

[0003] The core of the methanol-to-formaldehyde conversion is a catalytic oxidation reaction. Industrial production relies on specific catalysts and equipment. Methanol (CH3OH) reacts with oxygen (O2) in the presence of a catalyst to oxidize and remove hydrogen atoms to produce formaldehyde (HCHO). The reaction equation is as follows: CH3OH + ½O2 = HCHO + H2O This reaction is exothermic and requires specific temperature and catalyst conditions to improve reaction efficiency.

[0004] Currently, a chemical company faces the following risk factors during formaldehyde production: 1. Oxygen-to-methanol ratio (the ratio of oxygen to methanol): In the iron-molybdenum catalytic system, excess oxygen (high oxygen-to-methanol ratio) can ensure that methanol reacts fully, but it must be controlled outside the explosion limit (the explosion limit of methanol vapor is about 6.7% to 36%). II. Toxicity Risks: Both methanol and formaldehyde are toxic. The lethal dose of methanol via oral inhalation is approximately 10 mL to 30 mL, while formaldehyde inhalation can irritate the respiratory tract and long-term exposure is carcinogenic. III. Explosion Risk: Methanol vapor mixed with air can easily form an explosive mixture. Before the formaldehyde reaction, the gas concentration must be strictly controlled, and open flames or static electricity should be avoided.

[0005] The chemical company's measures to address the above risks are as follows: Sample gas is collected from the reaction gas input pipeline at the front end of the formaldehyde reaction equipment, and then taken to the laboratory for oxygen concentration analysis. Based on the oxygen content of the reaction gas, necessary adjustments are made to the formaldehyde reaction process parameters. However, before oxygen analysis in the laboratory, the sample gas needs to be pretreated. Pretreatment methods include removing moisture and impurities from the sample gas. This pretreatment process consumes a significant amount of time, ultimately leading to a lag (discontinuity) in the oxygen detection data. This deviation in gas detection data cannot meet the demands of industrial production for real-time and accurate monitoring of gas composition. Furthermore, the manual collection method used by personnel at the production site also presents problems such as gas loss interfering with the production process, as well as resource waste and environmental pollution.

[0006] In summary, gas detection methods based on formaldehyde reaction systems suffer from problems such as large deviations in detection data, serious interference with production processes, and environmental pollution caused by gas leakage. These issues have become urgent technical challenges for enterprises to address. Summary of the Invention

[0007] This invention provides an online gas detection device based on a formaldehyde reaction system, which overcomes the shortcomings of the prior art. It can effectively solve the problems of large deviation in detection data, serious interference of the detection method with the production process, and pollution caused by gas loss in the existing formaldehyde reaction system gas detection methods.

[0008] The technical solution of this utility model is achieved through the following measures: an online gas detection device based on a formaldehyde reaction system, comprising a gas mixer, a pressurizing device, a methanol vaporizer, a formaldehyde reactor, a water tank, and a gas analyzer. A first inlet of the gas mixer is fixedly connected to an exhaust gas pipeline. A pressurized air pipeline is fixedly connected between the outlet of the pressurizing device and the second inlet of the gas mixer. A mixed gas pipeline is fixedly connected between the outlet of the gas mixer and the top inlet of the methanol vaporizer. A first circulating fan and a second circulating fan are sequentially fixedly installed along the medium flow direction on the mixed gas pipeline. The upper inlet of the methanol vaporizer is fixedly... A methanol liquid pipeline is connected to the methanol vaporizer. A methanol vaporized gas pipeline is fixedly connected between the bottom outlet of the methanol vaporizer and the top inlet of the formaldehyde reactor. A first formaldehyde gas pipeline is fixedly connected between the bottom outlet of the formaldehyde reactor and the lower inlet of the methanol vaporizer. A second formaldehyde gas pipeline is fixedly connected between the lower outlet of the methanol vaporizer. A first bypass pipeline is fixedly connected between the mixed gas pipeline between the second circulating fan and the top inlet of the methanol vaporizer and the upper inlet of the water tank. A gas return pipeline is fixedly connected between the top outlet of the water tank and the mixed gas pipeline at the inlet of the first circulating fan. A gas analyzer is fixedly installed on the gas return pipeline.

[0009] The following are further optimizations and / or improvements to the above-mentioned utility model technical solution: A second bypass pipeline is fixedly connected between the first bypass pipeline and the gas return pipeline between the top outlet of the water tank and the inlet of the gas analyzer.

[0010] The bottom outlet of the aforementioned water tank is fixedly connected to a drainage pipe.

[0011] The aforementioned pressurization device includes one or more pressurization fans. Each pressurization fan has an air intake port that is fixedly connected to an atmospheric intake pipeline, and each pressurization fan has an air outlet that is fixedly connected to the pressurized air pipeline and a pressurization branch pipeline.

[0012] A spray device is fixedly installed in the upper part of the methanol vaporizer, and the inlet of the spray device is fixedly connected to a methanol liquid pipeline.

[0013] A heat exchange device is fixedly installed inside the methanol vaporizer at the bottom of the above-mentioned spraying device. A first formaldehyde gas pipeline is fixedly connected between the bottom outlet of the formaldehyde reactor and the lower inlet of the heat exchange device, and a second formaldehyde gas pipeline is fixedly connected to the upper outlet of the heat exchange device.

[0014] The formaldehyde reactor described above is equipped with a fixed catalyst bed. The lower inlet of the fixed catalyst bed is fixedly connected to a heat supply pipeline, the middle inlet of the fixed catalyst bed is fixedly connected to a cold medium input pipeline, and the upper outlet of the fixed catalyst bed is fixedly connected to a cold medium return pipeline.

[0015] A regulating valve is fixedly installed on the aforementioned methanol pipeline.

[0016] An inlet shut-off valve is fixedly installed on the first bypass pipeline between the second bypass pipeline and the upper inlet of the water tank. An outlet shut-off valve is fixedly installed on the gas return pipeline between the top outlet of the water tank and the second bypass pipeline. A bypass valve is fixedly installed on the second bypass pipeline. A drain valve is fixedly installed on the drain pipeline.

[0017] A pressure reducing valve is fixedly installed on the gas return line between the second bypass line and the gas analyzer inlet.

[0018] This utility model has a reasonable and compact structure and is easy to use. It adopts a closed-loop online gas detection method, which ensures the continuity and accuracy of detection data and avoids environmental pollution caused by gas loss, providing safe and reliable technical support for formaldehyde production processes. Attached Figure Description

[0019] Appendix Figure 1 This is a schematic diagram of the process flow of this utility model.

[0020] Appendix Figure 1 The codes in the diagram are as follows: 1 for gas mixer, 2 for methanol vaporizer, 3 for formaldehyde reactor, 4 for water tank, 5 for gas analyzer, 6 for exhaust gas pipeline, 7 for pressurized air pipeline, 8 for mixed gas pipeline, 9 for first circulating fan, 10 for second circulating fan, 11 for methanol liquid pipeline, 12 for methanol vaporized gas pipeline, 13 for first formaldehyde gas pipeline, 14 for second formaldehyde gas pipeline, 15 for first bypass pipeline, and 16 for gas. 17 is the return pipeline, 18 is the second bypass pipeline, 19 is the drain pipeline, 20 is the booster fan, 21 is the atmospheric intake pipeline, 22 is the booster branch pipeline, 23 is the spray device, 24 is the heat exchange device, 25 is the catalyst fixed bed, 26 is the heat medium replenishment pipeline, 27 is the refrigerant input pipeline, 28 is the refrigerant return pipeline, 29 is the regulating valve, 30 is the inlet shut-off valve, 31 is the outlet shut-off valve, 32 is the bypass valve, and 33 is the drain valve. Detailed Implementation

[0021] This utility model is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this utility model and the actual situation.

[0022] Unless otherwise specified, all equipment and devices used in this invention are existing, publicly known, and commonly used equipment and devices in the field.

[0023] In this utility model, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1: As shown in the attached document Figure 1 As shown, the online gas detection device based on the formaldehyde reaction system includes a gas mixer 1, a pressurizing device, a methanol vaporizer 2, a formaldehyde reactor 3, a water tank 4, and a gas analyzer 5. A waste gas pipeline 6 is fixedly connected to the first inlet of the gas mixer 1. A pressurized air pipeline 7 is fixedly connected between the outlet of the pressurizing device and the second inlet of the gas mixer 1. A mixed gas pipeline 8 is fixedly connected between the outlet of the gas mixer 1 and the top inlet of the methanol vaporizer 2. A first circulating fan 9 and a second circulating fan 10 are sequentially fixedly installed along the medium flow direction on the mixed gas pipeline 8. A methanol liquid pipeline 11 is fixedly connected to the upper inlet of the methanol vaporizer 2. A methanol vaporization gas pipeline 12 is fixedly connected between the bottom outlet of formaldehyde reactor 2 and the top inlet of formaldehyde reactor 3. A first formaldehyde gas pipeline 13 is fixedly connected between the bottom outlet of formaldehyde reactor 3 and the lower inlet of methanol vaporizer 2. A second formaldehyde gas pipeline 14 is fixedly connected between the lower outlet of methanol vaporizer 2. A first bypass pipeline 15 is fixedly connected between the mixed gas pipeline 8 between the second circulating fan 10 and the top inlet of methanol vaporizer 2 and the upper inlet of water tank 4. A gas return pipeline 16 is fixedly connected between the top outlet of water tank 4 and the mixed gas pipeline 8 at the inlet of the first circulating fan 9. A gas analyzer 5 is fixedly installed on the gas return pipeline 16.

[0025] The exhaust gas (mainly containing formaldehyde and oxygen) discharged from the top of the formaldehyde absorption tower in the upstream process system enters the gas mixer 1. The pressurization device blows atmospheric air into the gas mixer 1, where the exhaust gas is diluted and pressurized. Then, it is blown into the methanol vaporizer 2 by the first circulating fan 9 and the second circulating fan 10. The formaldehyde reactor 3 provides the heat required for methanol vaporization to the methanol vaporizer 2. The methanol vaporized gas in the formaldehyde reactor 3 reacts with oxygen under the action of a catalyst to generate high-temperature formaldehyde gas.

[0026] As needed, the water tank 4 has a gas buffering function. During the gas buffering process in the water tank 4, the moisture and impurities in the gas can settle to the bottom of the water tank 4. The gas in the upper part of the water tank 4 enters the gas return pipeline 16 and the oxygen content is detected by the gas analyzer 5.

[0027] As required, the gas analyzer 5 is an ABB EL3020. The gas analyzer 5 can detect the oxygen content in the gas entering the methanol vaporizer 2 at the top inlet online, providing reliable and accurate data support for adjusting the process parameters of the formaldehyde reactor 3.

[0028] This invention adopts a closed-loop online gas detection method, which ensures the continuity and accuracy of gas detection data, and avoids environmental pollution caused by gas loss, providing safe and reliable technical support for formaldehyde production processes.

[0029] The above-mentioned online gas detection device based on the formaldehyde reaction system can be further optimized and / or improved according to actual needs: Example 2: Its difference from Example 1 is as follows: (See attached) Figure 1 As shown, a second bypass line 17 is fixedly connected between the first bypass line 15 and the gas return line 16 between the top outlet of the water tank 4 and the inlet of the gas analyzer 5.

[0030] Example 3: Its difference from Examples 1 to 2 is as follows: (See attached) Figure 1 As shown, the bottom outlet of the water tank 4 is fixedly connected to a drainage pipe 18.

[0031] As needed, water and impurities accumulated at the bottom of the water tank 4 can be discharged through the drain line 18. When the water tank 4 needs to be drained, the water tank 4 stops the air intake and exhaust operations, and the medium in the first bypass line 15 enters the gas return line 16 through the second bypass line 17.

[0032] Example 4: Its difference from Examples 1 to 3 is as follows: (See attached) Figure 1 As shown, the booster device includes one or more booster fans 19. Each booster fan 19 has an air intake pipe 20 fixedly connected to its air inlet, and each booster fan 19 has a booster branch pipe 21 fixedly connected to its air outlet and the booster air pipe 7.

[0033] Depending on the needs and to meet the pressurization process requirements of this utility model, one or more pressurizing fans 19 can operate individually for pressurization, or multiple pressurizing fans 19 can operate simultaneously for pressurization.

[0034] Example 5: It differs from Examples 1 to 4 in that, as shown in the appendix... Figure 1As shown, a spray device 22 is fixedly installed in the upper part of the methanol vaporizer 2, and the inlet of the spray device 22 is fixedly connected to the methanol liquid pipeline 11.

[0035] As needed, methanol liquid enters the methanol vaporizer 2 and is sprayed by the spray device 22, which can improve the methanol liquid vaporization rate.

[0036] Example 6: Its difference from Examples 1 to 5 is as follows: (See attached) Figure 1 As shown, a heat exchange device 23 is fixedly installed inside the methanol vaporizer 2 at the bottom of the spray device 22. A first formaldehyde gas pipeline 13 is fixedly connected between the bottom outlet of the formaldehyde reactor 3 and the lower inlet of the heat exchange device 23. A second formaldehyde gas pipeline 14 is fixedly connected to the upper outlet of the heat exchange device 23.

[0037] As required, the heat exchange device 23 is a vertical shell-and-tube heat exchanger. The top inlets and bottom outlets of several tubes are fixed to the methanol vaporizer 2 by the upper tube sheet holder and the lower tube sheet holder, respectively. The heat exchange device 23 includes a tube side and a shell side. After being sprayed by the spray device 22, the methanol liquid flows down into the upper tube sheet holder and then enters the tube side of the heat exchange device 23 through the inlets of several tubes on the upper tube sheet holder. The methanol liquid in the tube side is heated and vaporized by the high-temperature methanol gas in the shell side.

[0038] Example 7: Its difference from Examples 1 to 6 is as follows: (See attached) Figure 1 As shown, a catalyst fixed bed 24 is fixedly installed inside the formaldehyde reactor 3. A heat medium replenishment pipeline 25 is fixedly connected to the lower inlet of the catalyst fixed bed 24, a cold medium input pipeline 26 is fixedly connected to the middle inlet of the catalyst fixed bed 24, and a cold medium return pipeline 27 is fixedly connected to the upper outlet of the catalyst fixed bed 24.

[0039] As needed, methanol vapor enters the formaldehyde reactor 3 and reacts with oxygen in the gas stream under the action of a catalyst to produce formaldehyde gas. This reaction initially requires a high-temperature environment, which can be achieved by introducing a heat transfer medium through the heat transfer medium supply line 25 to increase the ambient temperature of the catalyst bed 24 and improve the formaldehyde conversion rate. However, this reaction is also exothermic. If the ambient temperature of the catalyst bed 24 is too high, it will damage the catalyst activity within the catalyst bed 24. Therefore, a cold transfer medium can be introduced through the cold transfer medium supply line 26 to lower the ambient temperature of the catalyst bed 24.

[0040] Example 8: It differs from Examples 1 to 7 in that: as shown in the appendix Figure 1 As shown, a regulating valve 28 is fixedly installed on the methanol liquid pipeline 11.

[0041] Example 9: It differs from Examples 1 to 8 in that: as shown in the appendix Figure 1As shown, an inlet shut-off valve 29 is fixedly installed on the first bypass pipeline 15 between the second bypass pipeline 17 and the upper inlet of the water tank 4. An outlet shut-off valve 30 is fixedly installed on the gas return pipeline 16 between the top outlet of the water tank 4 and the second bypass pipeline 17. A bypass valve 31 is fixedly installed on the second bypass pipeline 17. A drain valve 32 is fixedly installed on the drain pipeline 18.

[0042] As needed, when draining the bottom of the water tank 4, the inlet shut-off valve 29 and outlet shut-off valve 30 should be closed first, the bypass valve 31 should be opened, and then the drain valve 32 should be opened to drain the water or sludge accumulated at the bottom of the water tank 4.

[0043] Example 10: It differs from Examples 1 to 9 in that, as shown in the appendix... Figure 1 As shown, a pressure reducing valve 33 is fixedly installed on the gas return line 16 between the second bypass line 17 and the inlet of the gas analyzer 5.

[0044] Depending on the needs, the pipelines and equipment of the online gas detection device of the formaldehyde reaction system may also be equipped with conventional valves, thermometers and pressure gauges known in the art, as required by production.

[0045] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0046] The usage process of this utility model embodiment is as follows: First, the exhaust gas discharged from the upstream process system enters the gas mixer 1 through the exhaust gas pipeline 6. At the same time, the pressurization device blows atmospheric air into the gas mixer 1 through the pressurized air pipeline 7 to dilute the exhaust gas and increase the airflow pressure. Next, the mixed gas in the gas mixer 1 is input into the methanol vaporizer 2 through the mixed gas pipeline 8. Methanol liquid is input into the spray device 22 of the methanol vaporizer 2 through the methanol liquid pipeline 11 for spraying. The airflow pressure at the top of the methanol vaporizer 2 disperses the methanol liquid downwards. The methanol liquid enters the heat exchange device 23 and is heated and vaporized to obtain methanol vaporized gas. Then, the methanol vaporized gas enters the formaldehyde reactor 3 through the methanol vaporized gas pipeline 12. The methanol vaporized gas and oxygen undergo an oxidation reaction in the catalyst fixed bed 24 to obtain high-temperature formaldehyde gas. Finally, the high-temperature formaldehyde gas enters the heat exchange device 23 of the methanol vaporizer 2 through the first formaldehyde gas pipeline 13 to provide heat to the heat exchange device 23 and obtain condensed formaldehyde gas. The condensed formaldehyde gas enters the downstream process system through the second formaldehyde gas pipeline 14.

[0047] The usage process of this utility model embodiment also includes: the mixed gas in the mixed gas pipeline 8 at the outlet of the second circulating fan 10 enters the water tank 4 for buffering through the first bypass pipeline 15. During the buffering process, the moisture and impurities in the mixed gas settle to the bottom of the water tank 4. The gas in the upper part of the water tank 4 enters the gas analyzer 5 through the gas return pipeline 16 for gas concentration detection. After detection, the gas flows back to the mixed gas pipeline 8 at the inlet of the first circulating fan 9 through the gas return pipeline 16.

Claims

1. An online gas detection device based on a formaldehyde reaction system, characterized in that... The system includes a gas mixer, a pressurizing device, a methanol vaporizer, a formaldehyde reactor, a water tank, and a gas analyzer. The first inlet of the gas mixer is fixedly connected to an exhaust gas pipeline. A pressurized air pipeline is fixedly connected between the outlet of the pressurizing device and the second inlet of the gas mixer. A mixed gas pipeline is fixedly connected between the outlet of the gas mixer and the top inlet of the methanol vaporizer. A first circulating fan and a second circulating fan are fixedly installed sequentially along the flow direction of the medium on the mixed gas pipeline. A methanol liquid pipeline is fixedly connected to the upper inlet of the methanol vaporizer. The bottom outlet of the methanol vaporizer is connected to the formaldehyde... A methanol vaporization gas pipeline is fixedly connected between the top inlet of the reactor and the bottom outlet of the formaldehyde reactor and the lower inlet of the methanol vaporizer. A first formaldehyde gas pipeline is fixedly connected between the bottom outlet of the formaldehyde reactor and the lower inlet of the methanol vaporizer. A second formaldehyde gas pipeline is fixedly connected between the lower outlet of the methanol vaporizer and the mixed gas pipeline between the second circulating fan and the top inlet of the methanol vaporizer. A first bypass pipeline is fixedly connected between the upper inlet of the water tank and the mixed gas pipeline at the top outlet of the water tank and the inlet of the first circulating fan. A gas analyzer is fixedly installed on the gas return pipeline.

2. The online gas detection device based on a formaldehyde reaction system according to claim 1, characterized in that... A second bypass line is fixedly connected between the first bypass line and the gas return line between the top outlet of the water tank and the inlet of the gas analyzer.

3. The online gas detection device based on a formaldehyde reaction system according to claim 1 or 2, characterized in that... The bottom outlet of the water tank is fixedly connected to a drainage pipe.

4. The online gas detection device based on a formaldehyde reaction system according to claim 3, characterized in that... The booster device includes one or more booster fans. Each booster fan has an air intake pipe fixedly connected to its air inlet, and each booster fan has a booster branch pipe fixedly connected to its air outlet and the booster air pipe.

5. The online gas detection device based on a formaldehyde reaction system according to claim 1, 2, or 4, characterized in that... A spray device is fixedly installed in the upper part of the methanol vaporizer, and the inlet of the spray device is fixedly connected to a methanol liquid pipeline.

6. The online gas detection device based on a formaldehyde reaction system according to claim 5, characterized in that... A heat exchange device is fixedly installed inside the methanol vaporizer at the bottom of the spraying device. A first formaldehyde gas pipeline is fixedly connected between the bottom outlet of the formaldehyde reactor and the lower inlet of the heat exchange device, and a second formaldehyde gas pipeline is fixedly connected to the upper outlet of the heat exchange device.

7. The online gas detection device based on a formaldehyde reaction system according to claim 6, characterized in that... A fixed catalyst bed is installed inside the formaldehyde reactor. The lower inlet of the fixed catalyst bed is fixedly connected to a heat supply pipeline, the middle inlet of the fixed catalyst bed is fixedly connected to a cold medium input pipeline, and the upper outlet of the fixed catalyst bed is fixedly connected to a cold medium return pipeline.

8. The online gas detection device based on a formaldehyde reaction system according to claim 6 or 7, characterized in that... A regulating valve is fixedly installed on the methanol liquid pipeline.

9. The online gas detection device based on a formaldehyde reaction system according to claim 8, characterized in that... An inlet shut-off valve is fixedly installed on the first bypass pipeline between the second bypass pipeline and the upper inlet of the water tank. An outlet shut-off valve is fixedly installed on the gas return pipeline between the top outlet of the water tank and the second bypass pipeline. A bypass valve is fixedly installed on the second bypass pipeline. A drain valve is fixedly installed on the drain pipeline.

10. The online gas detection device based on a formaldehyde reaction system according to claim 9, characterized in that... A pressure reducing valve is fixedly installed on the gas return line between the second bypass line and the gas analyzer inlet.

Images