A device for preparing methyl nitrite based on fuming nitric acid
The apparatus for preparing methyl nitrite using fuming nitric acid solves the problem of complex and expensive nitrogen source replenishment in the syngas-to-ethylene glycol process, simplifies operation, reduces costs, and can handle circulating gas under shutdown conditions, achieving efficient replenishment of methyl nitrite and preparation of fuming nitric acid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SICHUAN ZHENGDAKAI NEW MATERIAL CO LTD
- Filing Date
- 2025-06-06
- Publication Date
- 2026-06-12
AI Technical Summary
The existing nitrogen source replenishment methods in the syngas-to-ethylene glycol process are complex, expensive, and risky, resulting in nitrogen loss and high replenishment costs.
An apparatus for preparing methyl nitrite based on fuming nitric acid is adopted. By combining a booster, a NOx generator/absorption tower and a nitric acid reduction reaction tower, methyl nitrite is generated from fuming nitric acid, which simplifies the operation process and reduces operational risks and costs.
It simplifies nitrogen source replenishment operations, reduces costs, improves the economics of nitrogen source replenishment, and can process circulating gas to produce fuming nitric acid under shutdown conditions, making it suitable for syngas-to-ethylene glycol production systems.
Smart Images
Figure CN224345863U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of syngas-to-ethylene glycol process technology, specifically relating to an apparatus for preparing methyl nitrite based on fuming nitric acid. Background Technology
[0002] In existing industrial technologies, the syngas-to-ethylene glycol process commonly uses nitric oxide, oxygen, and methanol to produce methyl nitrite, which then reacts with carbon monoxide to produce the intermediate dimethyl oxalate, followed by hydrogenation to obtain ethylene glycol. In the actual production process of syngas-to-ethylene glycol, the esterification reaction consumes nitric oxide to produce nitric acid (4NO + 3O₂ + 2H₂O = 4HNO₃), the carbonylation reaction consumes nitric oxide to produce nitrogen gas (2NO + 2CO = 2CO₂ + N₂), and the purge gas contains a small amount of methyl nitrite. All of these factors lead to the loss of nitrogen (nitric oxide and methyl nitrite), necessitating the replenishment of nitrogen sources. Furthermore, nitrogen replenishment is also required during the start-up of the dimethyl oxalate synthesis unit. Currently, commonly used methods for nitrogen replenishment include: 1) the reaction of sodium nitrite with nitric acid, and 2) N₂O₄. The sodium nitrite-nitric acid reaction unit has a long start-up preparation time, is relatively complex to operate, and carries a high operational risk. Meanwhile, N₂O₄ is a highly hazardous and expensive material, resulting in high nitrogen replenishment costs. Therefore, we aim to develop a new nitrogen source replenishment method to improve the economics of nitrogen replenishment and reduce operational risks. Utility Model Content
[0003] The present invention aims to provide an apparatus for preparing methyl nitrite based on fuming nitric acid, so as to solve the problems of complex operation and high cost of traditional nitrogen source replenishment methods in the production of diethanol from syngas.
[0004] To achieve the above objectives, the present invention provides an apparatus for preparing methyl nitrite based on fuming nitric acid, comprising a booster compressor and a NO... x Oxidation / absorption tower and nitric acid reduction reaction tower, NO x The generator / absorption tower is equipped with a top gas phase outlet and a bottom liquid phase outlet, and the nitric acid reduction reaction tower is equipped with a top liquid phase inlet, a top gas phase outlet, a bottom gas phase inlet, and a bottom liquid phase outlet.
[0005] The outlet of the booster compressor and NO x The bottom gas inlet of the generator / absorber is connected via pipeline, NO x The top of the generator / absorption tower is connected to a nitric acid feed pipe, NO x The middle section of the generator / absorption tower is connected to a demineralized water feed pipe, the top liquid inlet of the nitric acid reduction reaction tower is connected to the bottom liquid pipeline of the esterification tower, and the NO... xThe bottom liquid phase outlet of the generator / absorption tower is connected via pipeline, and the bottom gas phase inlet of the nitric acid reduction reaction tower is connected to the NO... x The top gaseous outlet of the generator / absorption tower is connected by a pipeline, and the top gaseous outlet of the nitric acid reduction reaction tower is connected by a gaseous discharge pipe.
[0006] The working principle and beneficial effects of this scheme are as follows: In this scheme, the circulating gas from the carbonyl coupling system is pressurized by a booster before entering the NO3-NO3 system. x The fuming nitric acid, moving upwards from the bottom of the generation / absorption tower, enters the NO3-generating / absorbing tower through the nitric acid feed pipe. x NO2 dissolved in fuming nitric acid precipitates from the top of the generation / absorption tower and falls inside the tower, reacting with NO2. x The deionized water entering from the middle of the generation / absorption tower contacts and reacts to produce nitric acid and nitrous acid. Nitric acid is unstable and decomposes into water and N2O3. N2O3 is easily decomposed into NO2 and NO upon heating, and NO2 then reacts with water. Thus, NO... x NO, NO2, and N2O3, etc., generated in the reaction within the absorption tower x The gas enters the bottom of the nitric acid reduction reaction tower along with the circulating gas, while NO... x The bottom liquid (containing dilute nitric acid) from the generator / absorber is mixed with the methanol-containing bottom liquid from the esterification tower, which is then transported from the esterification tower bottom liquid pipeline. This mixture then reacts with NO in the circulating gas within the nitric acid reduction reaction tower. x The reaction produces methyl nitrite and water. The methyl nitrite is discharged through the gas phase outlet pipe and, after cooling and separation, can be sent to the esterification tower section for use, thus supplementing the nitrogen source (methyl nitrite) for the syngas-to-ethylene glycol production system. Furthermore, compared with traditional nitrogen supplementation methods, this scheme simplifies the operation process, reduces operational risks, and lowers nitrogen supplementation costs, showing great promise for industrial application.
[0007] Optionally, the NO x Both the generator / absorption tower and the nitric acid reduction reaction tower are equipped with top reflux feed inlets. x Pump I and heat exchanger I are installed on the pipeline between the bottom liquid phase outlet of the generator / absorption tower and the top liquid phase inlet of the nitric acid reduction reaction tower. The pipeline between heat exchanger I and the top liquid phase inlet of the nitric acid reduction reaction tower is connected to the NO... x The top reflux inlet of the generator / absorption tower is connected by a pipeline; the bottom liquid outlet of the nitric acid reduction reaction tower is connected to a liquid outlet pipe, and a pump II is installed on the liquid outlet pipe. The liquid outlet pipe is connected to the top reflux inlet of the nitric acid reduction reaction tower by a pipeline, and a heat exchanger II is installed on the pipeline between the liquid outlet pipe and the top reflux inlet of the nitric acid reduction reaction tower.
[0008] In this plan, NO xThe bottom liquid of the generator / absorber is a 10-15 wt% nitric acid solution. After being pumped by pump I and cooled to 50-55°C by heat exchanger I, a portion is then transferred to the NO3-O4 generator. x The top reflux from the generation / absorption tower continues to participate in the reaction, while another portion is sent to the top of the nitric acid reduction tower, i.e., part of the dilute nitric acid solution is refluxed to the NO₂ reaction tower. x In the generation / absorption tower, the amount of demineralized water used is reduced. In addition, the bottom liquid of the nitric acid reduction reaction tower is partially transported to heat exchanger II by pump II to be heated to 80°C and then refluxed through the top of the nitric acid reduction reaction tower to continue participating in the reaction, while the other part is transported to the methanol recovery section for methanol recovery.
[0009] Optionally, the gas phase discharge pipe is equipped with a heat exchanger III, and the end of the gas phase discharge pipe away from the nitric acid reduction reaction tower is connected to a reflux tank. The reflux tank has a top gas phase discharge port and a bottom liquid phase discharge port. The nitric acid reduction reaction tower has a middle reflux inlet. The top gas phase discharge port of the reflux tank is connected to the esterification tower via a pipeline, and the bottom liquid phase discharge port of the reflux tank is connected to the middle reflux inlet of the nitric acid reduction reaction tower via a pipeline.
[0010] In this scheme, the gas phase discharge temperature in the gas phase discharge pipe is relatively high. Before being sent to the esterification tower, the temperature of the gas phase discharge is reduced by heat exchanger III, and the methanol, nitric acid and trace water carried in the gas phase discharge are condensed into the reflux tank. The methanol, nitric acid and trace water in the reflux tank are then returned to the middle of the nitric acid reduction reaction tower to continue to participate in the reaction.
[0011] Optionally, it also includes a gas mixer and a nitric acid storage tank, the gas mixer being installed at the outlet of the booster compressor and the NO... x The pipeline between the bottom gas inlet of the generator / absorber tower, and the gas mixer is connected to an air inlet pipe; the bottom gas inlet of the nitric acid reduction reaction tower is connected to the NO... x The pipeline between the top gaseous outlet of the generator / absorber is connected to a tail gas delivery pipe. The pipeline between heat exchanger I and the top liquid inlet of the nitric acid reduction reaction tower is connected to the nitric acid storage tank via a pipeline. Furthermore, the pipelines between heat exchanger I and the top liquid inlet of the nitric acid reduction reaction tower, between heat exchanger I and the nitric acid storage tank, and between the bottom gaseous inlet of the nitric acid reduction reaction tower and the NO... x Valves are installed on the pipeline between the top gas phase outlet of the generator / absorption tower, the tail gas conveying pipe, the demineralized water feed pipe, and the air inlet pipe.
[0012] In this solution, if the esterification and carbonylation system is shut down, the medium route is changed via valves. The circulating gas is pressurized by a booster and mixed with outside air in a gas mixer, then passed through NO... x The gaseous feed enters the bottom of the generator / absorber and reacts to generate NO2 in the lower part of the tower. The nitric acid feed pipe then directs the NO2 into the gas.x The generator / absorption tower delivers a 68% nitric acid solution. The 68% nitric acid solution sprayed from the top of the tower comes into countercurrent contact with the rising gas from the bottom, dissolving NO2 into the nitric acid solution to form fuming nitric acid, thus removing NO. x The circulating gas is sent to the incinerator for treatment via the tail gas delivery pipe, while the fuming nitric acid in the tower bottom, after being cooled to 40°C by heat exchanger I under the delivery of pump I, is partially delivered to the NO3-NO ... x The top reflux from the generator / absorber continues to absorb nitrogen oxides, while another portion is sent to a nitric acid storage tank for storage. Thus, this method can supplement the methyl nitrite production system from syngas to ethylene glycol under both start-up and normal operating conditions, and can also receive and process recirculated gas to produce fuming nitric acid during shutdown conditions.
[0013] Optionally, the bottom of the nitric acid storage tank is connected to a nitric acid delivery pipe, and the end of the nitric acid delivery pipe away from the nitric acid storage tank is connected to a nitric acid feed pipe. A pump Ⅲ is installed on the nitric acid delivery pipe, and valves are provided on both the nitric acid delivery pipe and the nitric acid feed pipe 7.
[0014] In this scheme, under the delivery of pump III, the fuming nitric acid in the nitric acid storage tank can be delivered to the nitric acid feed pipe. In this way, the fuming nitric acid generated under shutdown conditions can be used under start-up conditions and normal operating conditions.
[0015] Optionally, the exhaust gas delivery pipe is connected to the air inlet of the booster via a pipeline, and a valve is provided on the pipeline between the exhaust gas delivery pipe and the air inlet of the booster.
[0016] In this solution, under shutdown conditions, the NO gas in the exhaust gas delivery pipe... x If the standard is not met, return to the booster compressor to continue NO production. x Remove.
[0017] Optionally, the nitric acid feed pipe includes a regular nitric acid feed pipe and a fuming nitric acid feed pipe, and both the regular nitric acid feed pipe and the fuming nitric acid feed pipe are equipped with valves.
[0018] In this plan, under both start-up and normal operating conditions, the valve on the ordinary nitric acid feed pipe is closed, while the valve on the fuming nitric acid feed pipe is open, allowing the fuming nitric acid to enter the NO3-NO ... x In the generator / absorber tower, under shutdown conditions, the valve on the feed pipe of ordinary nitric acid is open, while the valve on the feed pipe of fuming nitric acid is closed, allowing 68% nitric acid solution to enter the NO₂ production / absorption tower. x Generation / Absorption Tower. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the apparatus for preparing methyl nitrite based on fuming nitric acid in Embodiment 1 of this utility model;
[0020] Figure 2This is a schematic diagram of the apparatus for preparing methyl nitrite based on fuming nitric acid in Embodiment 2 of this utility model;
[0021] Figure 3 This is a schematic diagram of an apparatus for preparing methyl nitrite based on fuming nitric acid in Embodiment 3 of this utility model. Detailed Implementation
[0022] The following detailed description illustrates the specific implementation method:
[0023] The markings in the accompanying drawings of the instruction manual include: 1. Booster compressor; 2. Absorption tower; 3. Nitric acid reduction reaction tower; 4. Gas mixer; 5. Nitric acid storage tank; 6. Air inlet pipe; 7. Nitric acid feed pipe; 701. Ordinary nitric acid feed pipe; 702. Fuming nitric acid feed pipe; 8. Demineralized water feed pipe; 9. Pump I; 10. Heat exchanger I; 11. Pump II; 12. Heat exchanger II; 13. Heat exchanger III; 14. Reflux tank; 15. Tail gas delivery pipe; 16. Nitric acid delivery pipe; 17. Pump III; 18. Valve.
[0024] Example 1
[0025] This embodiment is basically as follows: Figure 1 As shown: An apparatus for preparing methyl nitrite based on fuming nitric acid, comprising a booster compressor 1, NO... x The system includes a generator / absorption tower 2, a nitric acid reduction reaction tower 3, a gas mixer 4, and a nitric acid storage tank 5, which stores fuming nitric acid. The booster compressor 1 has an inlet and an outlet for NO. x Oxidation / absorption tower 2 is a bubble tower, NO x The generator / absorption tower 2 is equipped with a top gas phase outlet, a bottom liquid phase outlet and a top liquid phase reflux outlet, and the nitric acid reduction reaction tower 3 is equipped with a top liquid phase inlet, a top gas phase outlet, a bottom gas phase inlet, a bottom liquid phase outlet, a top liquid phase reflux outlet and a middle liquid phase reflux outlet.
[0026] The air inlet of booster compressor 1 is connected to the circulating air pipeline via a pipeline, and the air outlet of booster compressor 1 is connected to the NO... x The bottom gas inlet of the generator / absorber tower 2 is connected via a pipeline, and the gas mixer 4 is installed at the outlet of the booster compressor 1 and the NO... x On the pipeline between the bottom gas phase inlet of the generator / absorption tower 2, the gas mixer 4 is connected to the air inlet pipe 6.
[0027] NO x The top of the generator / absorption tower 2 is connected to the nitric acid feed pipe 7, NO x The middle section of the generation / absorption tower 2 is connected to the demineralized water feed pipe 8, the top liquid inlet of the nitric acid reduction reaction tower 3, and the bottom liquid pipeline of the esterification tower, as well as the NO... xThe bottom liquid phase outlet of the generator / absorption tower 2 is connected via pipeline, and the bottom gas phase inlet of the nitric acid reduction reaction tower 3 is connected to the NO... x The top gaseous discharge port of generator / absorber 2 is connected via pipeline. x Pump I9 and heat exchanger I10 are installed on the pipeline between the bottom liquid phase outlet of the generator / absorption tower 2 and the top liquid phase inlet of the nitric acid reduction reaction tower 3. The pipeline between heat exchanger I10 and the top liquid phase inlet of the nitric acid reduction reaction tower 3 is connected to the NO... x The top reflux feed inlet of the generator / absorber tower 2 is connected via a pipeline.
[0028] The bottom liquid outlet of the nitric acid reduction reaction tower 3 is connected to a liquid discharge pipe, which is equipped with a pump II 11. The liquid discharge pipe is connected to the top reflux inlet of the nitric acid reduction reaction tower 3 via a pipeline, and a heat exchanger II 12 is installed on the pipeline between the liquid discharge pipe and the top reflux inlet of the nitric acid reduction reaction tower 3. The top gaseous outlet of the nitric acid reduction reaction tower 3 is connected to a gaseous discharge pipe, which is equipped with a heat exchanger III 13. The end of the gaseous discharge pipe away from the nitric acid reduction reaction tower 3 is connected to a reflux tank 14. The reflux tank 14 has a top gaseous outlet and a bottom liquid outlet. The nitric acid reduction reaction tower 3 has a middle reflux inlet. The top gaseous outlet of the reflux tank 14 is connected to the esterification tower via a pipeline, and the bottom liquid outlet of the reflux tank 14 is connected to the middle reflux inlet of the nitric acid reduction reaction tower 3 via a pipeline.
[0029] The bottom gas inlet of nitric acid reduction reaction tower 3 is in contact with NO. x A tail gas delivery pipe 15 is connected to the pipeline between the top gaseous outlet of the generator / absorption tower 2 and the tail gas delivery pipe 15, which is connected to the inlet of the booster compressor 1 via a pipeline. A pipeline between the heat exchanger I 10 and the top liquid inlet of the nitric acid reduction reaction tower 3 is connected to the nitric acid storage tank 5 via a pipeline. A nitric acid delivery pipe 16 is connected to the bottom of the nitric acid storage tank 5. The end of the nitric acid delivery pipe 16 furthest from the nitric acid storage tank 5 is connected to the nitric acid feed pipe 7. A pump III 17 is installed on the nitric acid delivery pipe 16. The pipelines between the heat exchanger I 10 and the top liquid inlet of the nitric acid reduction reaction tower 3, between the heat exchanger I 10 and the nitric acid storage tank 5, and between the bottom gaseous inlet of the nitric acid reduction reaction tower 3 and the NO... x Valves 18 are installed on the pipeline between the top gas outlet of the generator / absorption tower 2, the pipeline between the tail gas conveying pipe 15 and the air inlet of the booster 1, the tail gas conveying pipe 15, the nitric acid conveying pipe 16, the nitric acid feed pipe 7, the demineralized water feed pipe 8, and the air inlet pipe 6.
[0030] Under operating conditions or normal operating conditions (under operating conditions, the recirculated gas composition includes 25% CO and 75% N2; under normal operating conditions, the recirculated gas composition includes 25% CO, 13% methyl nitrite, 8% NO, and 54% N2), the recirculated gas from the carbonyl coupling system is pressurized by the booster compressor 1 and then enters the NO2 mixing chamber via the gas mixer 4 (valve 18 on the air intake pipe 6 is closed). x The fuming nitric acid is drawn from the bottom of the generation / absorption tower 2 and moves upwards within the tower. Simultaneously, under the action of pump Ⅲ17, the fuming nitric acid in the nitric acid storage tank 5 enters the NO3-NO ... x At the top of the generator / absorber tower 2, NO2 dissolved in fuming nitric acid precipitates out and reacts with NO2 entering through the demineralized water feed pipe 8. x In the middle of the generation / absorption tower 2, the demineralized water comes into contact with and reacts to produce nitric acid and nitrous acid. Nitric acid is unstable and decomposes into water and N2O3. N2O3 is easily decomposed into NO2 and NO upon heating, and NO2 then reacts with water. Thus, NO... x NO, NO2, and N2O3, etc., generated in the reaction within absorption tower 2 x The gas enters the bottom of the nitric acid reduction reaction tower 3 along with the circulating gas (valve 18 on the tail gas delivery pipe 15 and valve 18 on the pipeline between the tail gas delivery pipe 15 and the inlet of the booster 1 are closed), while NO... x The bottom liquid (10-15 wt% dilute nitric acid solution) of the generator / absorber 2 is cooled to 50-55°C by heat exchanger I10 under the action of pump I9, and a portion of it is then transported to the NO3-O4 generator. x The top reflux from generation / absorption tower 2 continues to participate in the reaction, while another portion is sent to the top of nitric acid reduction tower 3 (valve 18 on the pipeline between heat exchanger I10 and nitric acid storage tank 5 is closed). In NO... x The reaction equations inside the generator / absorption tower 2 are: (1) 2NO2+H2O=HNO3+HNO2; (2) 2HNO2=H2O+N2O3; (3) N2O3=NO+NO2 (reversible); the overall reaction is 3NO2+H2O=2HNO3+NO.
[0031] From NO x The bottom liquid of the generator / absorber tower 2 and the esterification tower liquid from the esterification tower liquid pipeline (the main components of the esterification tower bottom liquid are methanol, water, and nitric acid, of which the mass fraction of methanol is greater than 50%) are mixed and then reacted with NO in the circulating gas in the nitric acid reduction reaction tower 3. x(Mainly NO) reacts to produce methyl nitrite and water. Methyl nitrite, carried by the circulating gas, enters the gas phase outlet pipe and leaves the nitric acid reduction reaction tower 3. After being cooled by heat exchanger III13, it is sent to the esterification tower section for replenishment of methyl nitrite. During the cooling process, methanol, nitric acid, and trace amounts of water carried in the gas phase outlet are condensed into reflux tank 14. The methanol, nitric acid, and trace amounts of water in reflux tank 14 are then returned to the middle of the nitric acid reduction reaction tower 3 to continue participating in the reaction. Simultaneously, the bottom liquid of the nitric acid reduction reaction tower 3, under the action of pump II11, is partly transported to heat exchanger II12 to be heated to 80°C and then refluxed through the top of the nitric acid reduction reaction tower 3 to continue participating in the reaction; the other part is transported to the methanol recovery section (methanol distillation recovery unit) for methanol recovery.
[0032] Under shutdown conditions of the esterification and carbonylation system (the composition of the recirculated gas includes 25% CO, 23% NO, and 52% N2), the recirculated gas from the coupling carbonylation system is pressurized by the booster 1 and then enters the gas mixer 4. Outside air enters the gas mixer 4 through the air intake pipe 6 (with valve 18 on the air intake pipe 6 open). After the air mixes with the recirculated gas, it enters the NO2 / NO ... x NO2 is generated at the bottom of the generation / absorption tower 2; 68% nitric acid solution enters the NO2 production line through nitric acid feed pipe 7 (valve 18 on nitric acid feed pipe 7 is open, valve 18 on nitric acid delivery pipe 16 is closed). x At the top of the NO2 generation / absorption tower 2, the NO2-containing gas phase comes into countercurrent contact with a 68% nitric acid solution, dissolving the NO2 into the nitric acid solution to form fuming nitric acid. The fuming nitric acid in the tower bottom, under the action of pump I9, is cooled to 40°C by heat exchanger I10, and a portion is then transported to the NO2 generation / absorption tower. x The top reflux of the generation / absorption tower 2 continues to absorb nitrogen oxides, while the other portion is transported to the nitric acid storage tank 5 for storage (valve 18 on the pipeline between heat exchanger I 10 and nitric acid storage tank 5 is open, and valve 18 on the pipeline between heat exchanger I 10 and the bottom gas phase inlet of the nitric acid reduction reaction tower 3 is closed). Meanwhile, NO removal... x NO x (Concentration less than 100 PPM) is sent to the incinerator for treatment via tail gas conveying pipe 15 (valve 18 on tail gas conveying pipe 15 is open, and the bottom gas phase inlet of nitric acid reduction reaction tower 3 is connected to NO x (Valve 18 on the pipeline between the top gas outlet of the generator / absorber 2 is closed), if the NO in the circulating gas in the tail gas conveying pipe 15 is... x If the standard is not met, return to booster 1 to continue NO processing. x Remove (valve 18 on exhaust gas delivery pipe 15 is closed, and valve 18 on the pipeline between exhaust gas delivery pipe 15 and the air inlet of turbocharger 1 is opened).
[0033] In summary, this embodiment uses fuming nitric acid as a raw material to generate NO and nitric acid, which are then reacted with the methyl ester-containing bottom liquid of the esterification tower to generate methyl nitrite for use in the esterification tower. This achieves the replenishment of methyl nitrite, simplifies the nitrogen replenishment operation in the syngas-to-ethylene glycol production system, reduces operational risks, and lowers costs. Furthermore, this embodiment can also receive and process recirculated gas to produce fuming nitric acid under shutdown conditions for use under start-up or normal operating conditions, or to obtain a high-concentration nitric acid solution product.
[0034] Example 2
[0035] The difference between this embodiment and Embodiment 1 is that: Figure 2 As shown, the nitric acid feed pipe 7 in this embodiment includes a regular nitric acid feed pipe 701 and a fuming nitric acid feed pipe 702, and both the regular nitric acid feed pipe 701 and the fuming nitric acid feed pipe 702 are equipped with valves 18. In this embodiment, in addition to the fuming nitric acid supplied by the nitric acid storage tank 5, an additional fuming nitric acid feed pipe 702 is provided as a backup. When the concentration of fuming nitric acid in the nitric acid storage tank 5 is found to be unsatisfactory, NO is no longer supplied through the nitric acid storage tank 5. x Instead of providing fuming nitric acid from the generator / absorber 2, the fuming nitric acid is fed to NO through the nitric acid feed pipe 702. x The generator / absorber 2 provides fuming nitric acid. At this time, valve 18 on the ordinary nitric acid feed pipe 701 and valve 18 on the nitric acid delivery pipe 16 are closed, while valve 18 on the fuming nitric acid feed pipe 702 is open. During shutdown, valve 18 on the ordinary nitric acid feed pipe 701 is open, and valve 18 on the fuming nitric acid feed pipe 702 is closed, allowing 68% nitric acid solution to enter the NO₂ supply. x Generation / Absorption Tower 2.
[0036] Example 3
[0037] The difference between this embodiment and Embodiment 2 is that: Figure 3 As shown, in this embodiment, the nitric acid delivery pipe 16 and pump III are not included. In this embodiment, under start-up and normal operating conditions, valve 18 on the ordinary nitric acid inlet pipe 701 is closed, and valve 18 on the fuming nitric acid inlet pipe 702 is open, allowing fuming nitric acid to enter the NO3-NO ... x In the shutdown condition of the generation / absorption tower 2, valve 18 on the ordinary nitric acid feed pipe 701 is open, and valve 18 on the fuming nitric acid feed pipe 702 is closed, allowing 68% nitric acid solution to enter the NO₂ production / absorption tower. x Generation / Absorption Tower 2; NO xThe bottom liquid of the generator / absorption tower 2 is partially stored in the nitric acid storage tank 5 to obtain a high-concentration nitric acid solution product.
[0038] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness or practicality of this utility model. The specific embodiments described in the specification can be used to interpret the claims.
Claims
1. An apparatus for preparing methyl nitrite based on fuming nitric acid, characterized in that: Including booster compressors, NO x Oxidation / absorption tower and nitric acid reduction reaction tower, NO x The generator / absorption tower is equipped with a top gas phase outlet and a bottom liquid phase outlet, and the nitric acid reduction reaction tower is equipped with a top liquid phase inlet, a top gas phase outlet, a bottom gas phase inlet, and a bottom liquid phase outlet. The outlet of the booster compressor and NO x The bottom gas inlet of the generator / absorber is connected via pipeline, NO x The top of the generator / absorption tower is connected to a nitric acid feed pipe, NO x The middle section of the generator / absorption tower is connected to a demineralized water feed pipe, the top liquid inlet of the nitric acid reduction reaction tower is connected to the bottom liquid pipeline of the esterification tower, and the NO... x The bottom liquid phase outlet of the generator / absorption tower is connected via pipeline, and the bottom gas phase inlet of the nitric acid reduction reaction tower is connected to the NO... x The top gaseous outlet of the generator / absorption tower is connected by a pipeline, and the top gaseous outlet of the nitric acid reduction reaction tower is connected by a gaseous discharge pipe.
2. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 1, characterized in that: The NO x Both the generator / absorption tower and the nitric acid reduction reaction tower are equipped with top reflux feed inlets. x Pump I and heat exchanger I are installed on the pipeline between the bottom liquid phase outlet of the generator / absorption tower and the top liquid phase inlet of the nitric acid reduction reaction tower. The pipeline between heat exchanger I and the top liquid phase inlet of the nitric acid reduction reaction tower is connected to the NO... x The top reflux inlet of the generator / absorption tower is connected by a pipeline; the bottom liquid outlet of the nitric acid reduction reaction tower is connected to a liquid outlet pipe, and a pump II is installed on the liquid outlet pipe. The liquid outlet pipe is connected to the top reflux inlet of the nitric acid reduction reaction tower by a pipeline, and a heat exchanger II is installed on the pipeline between the liquid outlet pipe and the top reflux inlet of the nitric acid reduction reaction tower.
3. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 1 or 2, characterized in that: The gas phase discharge pipe is equipped with a heat exchanger III. The end of the gas phase discharge pipe away from the nitric acid reduction reaction tower is connected to a reflux tank. The reflux tank has a top gas phase discharge port and a bottom liquid phase discharge port. The nitric acid reduction reaction tower has a middle reflux inlet. The top gas phase discharge port of the reflux tank is connected to the esterification tower via a pipeline, and the bottom liquid phase discharge port of the reflux tank is connected to the middle reflux inlet of the nitric acid reduction reaction tower via a pipeline.
4. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 2, characterized in that: It also includes a gas mixer and a nitric acid storage tank. The gas mixer is installed at the outlet of the booster compressor and the NO... x The pipeline between the bottom gas inlet of the generator / absorber tower, and the gas mixer is connected to an air inlet pipe; the bottom gas inlet of the nitric acid reduction reaction tower is connected to the NO... x The pipeline between the top gaseous outlet of the generator / absorber is connected to a tail gas delivery pipe. The pipeline between heat exchanger I and the top liquid inlet of the nitric acid reduction reaction tower is connected to the nitric acid storage tank via a pipeline. Furthermore, the pipelines between heat exchanger I and the top liquid inlet of the nitric acid reduction reaction tower, between heat exchanger I and the nitric acid storage tank, and between the bottom gaseous inlet of the nitric acid reduction reaction tower and the NO... x Valves are installed on the pipeline between the top gas phase outlet of the generator / absorption tower, the tail gas conveying pipe, the demineralized water feed pipe, and the air inlet pipe.
5. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 4, characterized in that: The bottom of the nitric acid storage tank is connected to a nitric acid delivery pipe. The end of the nitric acid delivery pipe away from the nitric acid storage tank is connected to a nitric acid feed pipe. A pump III is installed on the nitric acid delivery pipe, and valves are provided on both the nitric acid delivery pipe and the nitric acid feed pipe.
6. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 4 or 5, characterized in that: The exhaust gas delivery pipe is connected to the air inlet of the turbocharger via a pipeline, and a valve is installed on the pipeline between the exhaust gas delivery pipe and the air inlet of the turbocharger.
7. The apparatus for preparing methyl nitrite based on fuming nitric acid according to claim 4 or 5, characterized in that: The nitric acid feed pipe includes a regular nitric acid feed pipe and a fuming nitric acid feed pipe, and both the regular nitric acid feed pipe and the fuming nitric acid feed pipe are equipped with valves.