Pilot-scale test system for preparing methyl formate through CO esterification, container type pilot-scale test device and production method

Abstract

The invention discloses a pilot plant test system for preparing methyl formate through CO esterification, a container type pilot plant test device and a production method, and belongs to the field of ester chemicals prepared through CO esterification. The container-type pilot plant adopts a container-type skid-mounted design, is small in occupied area, easy to move and rapid, simple and convenient to mount on site, and can meet the temporary requirements of more occasions on the pilot plant. The production method comprises the steps of mixing, pressurization, esterification, reaction, separation, rectification, product storage, public engineering, three-waste treatment, detection and DCS control, and factors in all process units, among all process units, environmental protection, by-product analysis, detection and control and the like can be investigated and verified. The small-scale continuous production of methyl formate can be realized; based on a pilot test result, amplification and even industrialization of the technology can be promoted.

Description

Technical Field

[0001] The present application relates to a pilot system for preparing methyl formate by CO esterification, a containerized pilot plant and a production method, and belongs to the field of preparing ester chemicals by carbon monoxide esterification. Background Art

[0002] Methyl formate is an important C1 chemical product and an important organic synthesis intermediate with a wide range of uses. In the chemical industry, it is an important intermediate for formic acid, amides and other products. It can be used to make formic acid, formamide, dimethylformamide, methyl methacrylate, high-purity CO, formate, etc. It is also a synthetic raw material for drugs such as sulfonyl methylpyrimidine, sulfonyl methoxypyrimidine, and antitussive dextromethorphan in the pharmaceutical industry. It can also be used as a fumigant and fungicide for treating tobacco, dried fruits, grains, etc.

[0003] The main methods for producing methyl formate include: methanol formate esterification, liquid-phase methanol carbonylation, methanol dehydrogenation, methanol oxidative dehydrogenation, formaldehyde dimerization, and direct synthesis of synthesis gas. At present, the main production technology of methyl formate in industry at home and abroad is the liquid-phase methanol carbonylation process. The liquid-phase methanol carbonylation process is a process in which methanol and carbon monoxide react to produce methyl formate under the action of sodium methoxide catalyst, that is, carbon monoxide and methanol are mixed with sodium methoxide catalyst to undergo carbonylation reaction under a certain pressure and temperature to produce methyl formate. This process has certain technical limitations: 1) The catalyst sodium methoxide is sensitive to water, so the water content in the raw material methanol must be below the ppm level; 2) The catalyst sodium methoxide is a strong base and corrodes the equipment, so the investment cost of the reactor is relatively high; and solid waste will be generated accordingly, which is not only easy to block the valve, but also brings difficulties to the actual operation; 3) The reaction is a homogeneous reaction, and the catalyst and the product need to be further separated, which is more troublesome; 4) This method cannot achieve continuous production of methyl formate.

[0004] In view of the problems existing in the existing liquid phase process and with the increase in demand for methyl formate and its downstream, many units at home and abroad are developing gas-phase CO direct esterification technology for methyl formate. However, on the one hand, most of the currently developed CO esterification production technologies for methyl formate and the corresponding catalysts are in the laboratory research stage, and there are still no reports on pilot studies and industrial tests of this technology. Generally speaking, pilot verification for at least thousands of hours is one of the necessary processes for the industrialization of technology. On the other hand, currently pilot evaluation devices are usually installed in fixed locations, but in fact many places are not suitable for the construction of permanent fixed buildings, and the demand for temporary use of pilot evaluation devices is increasing. Summary of the invention

[0005] The object of the present invention is to provide a container-type full-process process pilot device for preparing methyl formate by CO esterification.

[0006] According to a first aspect of the present application, a pilot system for preparing methyl formate by CO esterification is provided.

[0007] A CO esterification pilot system for preparing methyl formate, the CO esterification pilot system comprising a methyl nitrite gas pipeline, a nitrogen gas pipeline, a carbon monoxide gas pipeline, a hydrogen gas pipeline, an oxygen gas pipeline, a methanol pipeline, a circulating gas booster unit (1), an esterification tower (2), a preheating tower (3), a reactor (4), a dehydrogenation reactor (5), an elution tower (6), a first distillation tower (7), a dimethyl oxalate storage tank (8), a second distillation tower (9), a third distillation tower (10), a methyl formate storage tank (11), a methylal storage tank (12), a methanol storage tank (13), a purge unit (14), and a tail gas absorption tank (15);

[0008] The methyl nitrite gas pipeline, the nitrogen gas pipeline, the carbon monoxide gas pipeline, the hydrogen gas pipeline and the circulating gas pipeline are connected to the inlet of the circulating gas boosting unit (1), the outlet of the circulating gas boosting unit (1) and the oxygen gas pipeline are connected to the inlet of the middle and lower ends of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower (2) via a liquid pump;

[0009] The inlet of the preheater (3) is connected to the outlet of the top of the esterification tower (2), the inlet of the reactor (4) is connected to the outlet of the preheater (3), the inlet of the dehydrogenation reactor (5) is connected to the outlet of the reactor (4), the lower inlet of the elution tower (6) is connected to the outlet of the dehydrogenation reactor (5), the top of the elution tower (6) is directly connected to the inlet of the booster unit (1) and connected to the tail gas absorption tank (15) through the release unit (14);

[0010] The material inlet of the first distillation tower (7) is connected to the bottom of the elution tower (6) through a feed pump, the bottom outlet of the first distillation tower (7) is connected to the dimethyl oxalate storage tank (8), the material inlet of the second distillation tower (9) is connected to the top outlet of the first distillation tower (7) through a feed pump, the methanol storage tank (13) is connected to the bottom outlet of the second distillation tower (9) through a feed pump, the material inlet of the third distillation tower (10) is connected to the top outlet (9) of the second distillation unit through a feed pump, the top outlet of the third distillation tower (10) is connected to the methyl formate storage tank (11), and the bottom outlet of the third distillation tower (10) is connected to the methyl acetal storage tank (12).

[0011] Optionally, the reactor (4) is a tubular reactor with a multi-stage structure design;

[0012] A plurality of temperature control points are arranged at different axial heights in the reactor (4) to monitor the temperature of each catalyst bed in the reactor (4);

[0013] The radial distribution position of the temperature sensor in the tube of the reactor (4) is adjustable so as to simultaneously monitor the radial temperature distribution in the catalyst bed;

[0014] The reactor (4) is connected to the heat transfer oil system by means of a quick-opening flange.

[0015] Multiple temperature control points are set at different axial heights in the reactor to monitor the temperature of each catalyst bed in the reactor; and the radial distribution position of the temperature sensor in the tube is adjustable, so the radial temperature distribution in the catalyst bed can be monitored simultaneously; the reactor is connected to the heat transfer oil system through a quick-opening flange, which is easy to disassemble and suitable for the study of catalyst loading schemes; at the same time, the connecting flange between the heat transfer oil and the reactor shell reserves sufficient space, so that reactors of different sizes can be replaced.

[0016] Reactor (4) adopts a fixed bed tubular reactor with a multi-stage structure, which can not only perform conventional catalyst performance evaluation, but also study and verify the influence of factors such as catalyst particle size, filling scheme, heat transfer, and reactor structure.

[0017] Optionally, the circulating gas pressurizing unit (1) comprises a mixer, a buffer tank group and a compressor group;

[0018] The esterification tower (2) comprises an esterification reaction tower and a matching condensation device and a storage tank group.

[0019] Optionally, the release unit (14) comprises a pneumatic flow control valve, a flow meter, and a pressure gauge.

[0020] Optionally, the distillation tower includes a distillation tower body and its matching preheater, condenser and reflux tank.

[0021] According to the second aspect of the present application, a containerized pilot plant for preparing methyl formate by CO esterification is provided. The containerized skid-mounted design is adopted, the equipment occupies a small area, is easy to move, and has fast, simple and convenient on-site installation, which can meet the temporary needs of the pilot plant in more occasions.

[0022] A containerized pilot plant for preparing methyl formate by CO esterification, the pilot plant comprising a container, a pilot system for preparing methyl formate by CO esterification, a utility unit, an automatic control unit, and an analysis unit;

[0023] The CO esterification system for preparing methyl formate, the utility unit, the automation control unit, and the analysis unit are all arranged in a container;

[0024] The pilot plant system for preparing methyl formate by CO esterification is selected from the pilot plant system described above.

[0025] Optionally, the utility unit includes a heating circulation system, a cooling water circulation system, a chilled water circulation system, a vacuum pump, and an air compressor;

[0026] The heating circulation system is connected to the preheater (3), the reactor (4), the first distillation tower (7), the second distillation tower (9), and the third distillation tower (10) through pipelines; the cooling water circulation system is connected to the compressor unit and the heat transfer oil system; the refrigerated water circulation system is connected to the esterification tower (2), the elution tower, and the methyl formate storage tank (11); and the vacuum pump is connected to the esterification tower (2), the reactor (4), and the elution tower (6).

[0027] Optionally, the heating circulation system uses heat transfer oil or water vapor, and the temperature range is 0 to 300°C.

[0028] Optionally, the chilled water circulation system uses an ethylene glycol aqueous solution with a temperature range of -60 to 20°C.

[0029] Optionally, the automation control unit includes a detection unit, a control unit, and an execution unit;

[0030] Among them, the detection unit includes a remote pressure sensor, a remote liquid level sensor and a remote temperature sensor; the control unit adopts a distributed control system; the execution unit includes pneumatic, electric switching valves, and electric heating.

[0031] Optionally, the control unit includes a power distribution cabinet and a DCS-based control system.

[0032] Optionally, the analysis unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer.

[0033] Optionally, the inlet and outlet of the esterification tower (2), the inlet and outlet of the reactor (4), and the top of the elution tower (6) are all connected to an analysis unit for real-time online analysis.

[0034] Optionally, artificial sampling ports are provided at the top and the bottom of the first distillation tower (7) and the second distillation tower (9).

[0035] Optionally, the CO esterification system for preparing methyl formate, the utility unit, the automation control unit, the analysis unit and the equipment in the container are fixedly connected by welding, bolting or clamping.

[0036] According to a third aspect of the present application, a method for producing methyl formate by CO esterification is provided.

[0037] A production method for preparing methyl formate by CO esterification, the production method adopts the pilot system described above;

[0038] The following steps are involved:

[0039] The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas booster unit (1) and are boosted, and the boosted mixed gas and oxygen enter the middle and lower ends of the esterification tower (2), and then the methanol pipeline enters the upper end of the esterification tower (2) through a fluid pump, and undergoes an esterification reaction with the mixed gas in the esterification tower (2) to generate methyl nitrite;

[0040] The gas effluent from the upper end of the esterification tower (2) enters the preheating tower (3) for preheating, and the preheated gas enters the reactor (4) to contact with the catalyst for reaction; the effluent from the lower end of the reactor (4) enters the dehydrogenation reactor (5) for dehydrogenation, and then enters the elution tower (6) for separation, and is absorbed by cold methanol. The liquid product enters the first distillation tower (7) through a liquid pump for gas-liquid separation, the top product of the first distillation tower (7) enters the second distillation tower (9), the bottom product of the first distillation tower (7) enters the dimethyl oxalate storage tank (8), the top product of the second distillation tower (9) enters the third distillation tower (10), the bottom product of the second distillation tower (9) enters the methanol storage tank (13), the top product of the third distillation tower (10) enters the methyl formate storage tank (11), and the bottom product of the third distillation tower enters the methyl acetal storage tank (12).

[0041] Optionally, the operating parameters of the circulating gas booster unit (1) are as follows: methyl nitrite flow rate 0-16 SLPM, carbon monoxide flow rate 0-25 SLPM; nitrogen flow rate 0-30 SLPM; hydrogen flow rate 0-8 SLPM, and the design pressure is 1 MPa;

[0042] The operating parameters of the esterification tower (2) are as follows: methanol flow rate 0-1.68Kg / h, circulating gas flow rate 0-80SLPM, oxygen flow rate 0-4SLPM, designed operating temperature 0-200°C, and operating pressure 0-1Mpa;

[0043] The operating parameters of the reactor (4) are as follows: the operating space velocity is 0 to 5000 h -1 , the maximum design temperature is 200℃;

[0044] The operating parameters of the first distillation tower (7), the second distillation tower (9) and the third distillation tower (10) are as follows: height-to-diameter ratio of 26 to 65:1, operating temperature of 0 to 200°C, and design pressure of 0.4 MPa.

[0045] Optionally, the length of the reactor (4) is 0.5 to 10 m, the inner diameter of a single tube is 10 to 50 mm, the material is 304, 304L, 316, 316L, and the pressure resistance range is 0 to 5 MPa.

[0046] In this application, the reaction principle of direct esterification of CO to produce methyl formate is as follows:

[0047] 2CO+2CH3ONO+H2=2HCOOCH3+2NO (1)

[0048] 2CH3ONO+CH3OH→CH3OCH2OCH3+H2O+2NO (2)

[0049] 2CO+CH3ONO=(CH3OCO)2+2NO (3)

[0050] 2CH3ONO+H2=2CH3OH+2NO (4)

[0051] 2NO+2CH3OH+0.5O2=2CH3ONO+H2O (5)

[0052] Reaction (1) is the main reaction of CO esterification to produce methyl formate, which is carried out on the catalyst surface in the reactor, and the catalyst is a precious metal catalyst; reactions (2) and (3) are carried out on the catalyst surface in the reactor, and are side reactions in the process of producing methyl formate; reaction (4) is the main reaction in the dehydrogenation reactor, which is carried out on the catalyst surface; reaction (5) is the reaction of regenerating tail gas nitric oxide into methyl nitrite, which is carried out in the esterification tower.

[0053] According to the fourth aspect of the present application, a full-process production method for preparing methyl formate by CO esterification is provided. The full-process process includes mixing, pressurization, esterification, reaction, separation, distillation, product storage, public works, three wastes treatment, detection and DCS control, and can inspect and verify factors such as within each process unit, between each process unit, and environmental protection, by-products, analysis, detection and control.

[0054] A full-process production method for preparing methyl formate by CO esterification, wherein the full-process production method adopts the pilot plant described above;

[0055] The following steps are involved:

[0056] S1. Check all settings on all hardware devices and control software;

[0057] S2. Start the utility unit, prepare the gas and liquid raw materials, ensure the pressure and liquid level of each storage tank are normal, and load the catalyst;

[0058] S3. Turn on the analysis unit and power on all instruments, pumps, heaters, heating cables and other equipment; supply cooling water, chilled water, heat transfer oil and instrument gas required for the common project; and set all manual and automatic valves to initial values;

[0059] S4. Check air tightness and start vacuum replacement;

[0060] S5, first introduce nitrogen, and start the circulating gas booster unit (1) and the elution tower (6);

[0061] S6, after the circulating gas booster unit (1) is stably operating, carbon monoxide, methyl nitrite and hydrogen are introduced, and the temperature is raised to the reaction temperature, while monitoring the temperature, pressure, liquid level, flow rate, composition and other process parameters of each process unit in the system until the reactor (4) operates normally;

[0062] S7. After the reactor (4) operates normally, the esterification tower (2) is opened to allow the nitric oxide in the circulating gas to be regenerated into the raw material gas methyl nitrite;

[0063] S8. When the elution tower (6) reaches a preset liquid level, the first distillation tower (7), the second distillation tower (9) and the third distillation tower (10) can be started, and the heating and feeding of the corresponding towers can be started to ensure stable operation of the distillation towers.

[0064] S9. When the pilot plant reaches steady-state operation, on the one hand, the methyl formate product is gradually collected, and on the other hand, the process parameters of each process unit in the pilot plant are gradually collected and optimized.

[0065] When the pilot plant reaches steady-state operation, on the one hand, methyl formate product can be gradually collected, and on the other hand, the process parameters of each process unit in the pilot plant can be gradually optimized and explored; the loading scheme of the catalyst in the reactor, the radial temperature distribution in each bed layer, the temperature distribution on different axial beds, and the catalyst performance (selectivity, conversion rate, space-time yield) are analyzed and studied.

[0066] The beneficial effects of this application include:

[0067] 1) The containerized pilot plant for preparing methyl formate by CO esterification provided in this application adopts a containerized skid-mounted structure, with a small footprint, and fast, simple and convenient transportation and on-site installation, which can meet the temporary needs of pilot plants in more occasions. A fixed-bed tubular reactor and a multi-stage structure are adopted, which can not only perform conventional catalyst performance evaluation, but also study and verify the influence of factors such as catalyst particle size, filling scheme, heat transfer, and reactor structure. The use of an automated DCS control system can greatly reduce labor costs, which is beneficial to the long-term operation of the device, and is suitable for research institutes, enterprises, schools and other units to conduct scale-up process tests and catalyst performance inspections of CO esterification technology.

[0068] 2) The full-process production method of methyl formate produced by CO esterification provided in this application includes pressurization, esterification, mixing, reaction, separation, distillation, product storage, public works, three wastes treatment, detection and DCS control, and can investigate and verify factors such as each process unit (esterification tower, reactor, elution tower, distillation tower), between each process unit, and environmental protection, by-products, analysis and detection, DCS control, etc. Not only can small-scale continuous production of methyl formate be achieved; based on the results of the pilot test, the technology can also be scaled up and even industrialized. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 Schematic diagram of the process flow for producing methyl formate by CO esterification.

[0070] Figure 2 This is a schematic diagram of the exterior design of a containerized pilot plant for producing methyl formate by CO esterification.

[0071] Figure 3 This is an on-site photo of the containerized pilot plant for producing methyl formate by CO esterification.

[0072] Figure 4 This is the design diagram of the fixed bed tubular reactor.

[0073] List of parts and reference numerals:

[0074] 1. Circulating gas booster unit 2. Esterification tower 3. Preheating tower

[0075] 4. Reactor 5. Dehydrogenation reactor 6. Elution tower

[0076] 7. First distillation tower 8. Dimethyl oxalate storage tank 9. Second distillation tower

[0077] 10. The third distillation tower 11. Methyl formate storage tank 12. Methylal storage tank

[0078] 13. Methanol storage tank 14. Release unit 15. Tail gas absorption tank DETAILED DESCRIPTION

[0079] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0080] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0081] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0082] Example 1

[0083] like Figure 1The figure shows a schematic diagram of the process flow of preparing methyl formate by CO esterification. It includes a methyl nitrite gas pipeline, a nitrogen gas pipeline, a carbon monoxide gas pipeline, a hydrogen gas pipeline, an oxygen gas pipeline, a methanol pipeline, a circulating gas booster unit (1), an esterification tower (2), a preheating tower (3), a reactor (4), a dehydrogenation reactor (5), an elution tower (6), a first distillation tower (7), a dimethyl oxalate storage tank (8), a second distillation tower (9), a third distillation tower (10), a methyl formate storage tank (11), a methylal storage tank (12), a methanol storage tank (13), a release unit (14), and a tail gas absorption tank (15);

[0084] The methyl nitrite gas pipeline, the nitrogen gas pipeline, the carbon monoxide gas pipeline, the hydrogen gas pipeline and the circulating gas pipeline are connected to the inlet of the circulating gas boosting unit (1), the outlet of the circulating gas boosting unit (1) and the oxygen gas pipeline are connected to the inlet of the middle and lower ends of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower (2) via a liquid pump;

[0085] The inlet of the preheater (3) is connected to the outlet of the top of the esterification tower (2), the inlet of the reactor (4) is connected to the outlet of the preheater (3), the inlet of the dehydrogenation reactor (5) is connected to the outlet of the reactor (4), the lower inlet of the elution tower (6) is connected to the outlet of the dehydrogenation reactor (5), the top of the elution tower (6) is directly connected to the inlet of the booster unit (1) and connected to the tail gas absorption tank (15) through the release unit (14);

[0086] The material inlet of the first distillation tower (7) is connected to the bottom of the elution tower (6) through a feed pump, the bottom outlet of the first distillation tower (7) is connected to the dimethyl oxalate storage tank (8), the material inlet of the second distillation tower (9) is connected to the top outlet of the first distillation tower (7) through a feed pump, the methanol storage tank (13) is connected to the bottom outlet of the second distillation tower (9) through a feed pump, the material inlet of the third distillation tower (10) is connected to the top outlet (9) of the second distillation unit through a feed pump, the top outlet of the third distillation tower (10) is connected to the methyl formate storage tank (11), and the bottom outlet of the third distillation tower (10) is connected to the methyl acetal storage tank (12).

[0087] The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas booster unit (1) and are boosted, and the boosted mixed gas and oxygen enter the middle and lower ends of the esterification tower (2), and then the methanol pipeline enters the upper end of the esterification tower (2) through a fluid pump, and undergoes an esterification reaction with the mixed gas in the esterification tower (2) to generate methyl nitrite;

[0088] The gas effluent from the upper end of the esterification tower (2) enters the preheating tower (3) for preheating, and the preheated gas enters the reactor (4) to contact with the catalyst for reaction; the effluent from the lower end of the reactor (4) enters the dehydrogenation reactor (5) for dehydrogenation, and then enters the elution tower (6) for separation, and is absorbed by cold methanol. The liquid product enters the first distillation tower (7) through a liquid pump for gas-liquid separation, the top product of the first distillation tower (7) enters the second distillation tower (9), the bottom product of the first distillation tower (7) enters the dimethyl oxalate storage tank (8), the top product of the second distillation tower (9) enters the third distillation tower (10), the bottom product of the second distillation tower (9) enters the methanol storage tank (13), the top product of the third distillation tower (10) enters the methyl formate storage tank (11), and the bottom product of the third distillation tower enters the methyl acetal storage tank (12).

[0089] Figure 2 This is a schematic diagram of the exterior design of a containerized pilot plant for producing methyl formate by CO esterification. Figure 3 This is a site photo of the containerized pilot plant for methyl formate production by CO esterification. The pilot plant includes a container, a pilot system for methyl formate production by CO esterification, a utility unit, an automatic control unit, and an analysis unit; the methyl formate production by CO esterification system, the utility unit, the automatic control unit, and the analysis unit are all arranged in the container; the equipment in the methyl formate production by CO esterification system, the utility unit, the automatic control unit, and the analysis unit are fixedly connected to the container by welding, bolting, or clamping.

[0090] The utility unit comprises a heating circulation system, a cooling water circulation system, a refrigerating water circulation system, a vacuum pump and an air compressor; wherein the heating circulation system is connected to the preheater (3), the reactor (4), the first distillation tower (7), the second distillation tower (9) and the third distillation tower (10) through pipelines; the cooling water circulation system is connected to the compressor unit and the heat transfer oil system; the refrigerating water circulation system is connected to the esterification tower (2), the elution tower and the methyl formate storage tank (11); and the vacuum pump is connected to the esterification tower (2), the reactor (4) and the elution tower (6).

[0091] The automation control unit includes a detection unit, a control unit, and an execution unit; the detection unit includes a remote pressure sensor, a remote liquid level sensor, and a remote temperature sensor; the control unit adopts a distributed control system; the execution unit includes pneumatic and electric switch valves, and electric heating. The control unit includes a power distribution cabinet and a control system based on DCS.

[0092] The analysis unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer. The inlet and outlet of the esterification tower (2), the inlet and outlet of the reactor (4), and the top of the elution tower (6) are all connected to the analysis unit for real-time online analysis. Artificial sampling ports are provided at the top and bottom of the first distillation tower (7) and the second distillation tower (9).

[0093] The release unit (14) comprises a pneumatic flow regulating valve, a flow meter and a pressure gauge.

[0094] The heating circulation system uses heat transfer oil with a temperature range of 0 to 300°C. The chilled water circulation system uses ethylene glycol aqueous solution with a temperature range of -60 to 20°C.

[0095] The equipment parameters of the circulating gas booster unit are as follows: methyl nitrite flow rate 0-16SLPM, carbon monoxide flow rate 0-25SLPM; nitrogen flow rate 0-30SLPM; hydrogen flow rate 0-8SLPM; the pipeline mixer adopts SV type, and the design pressure is 1MPa; the design height of the buffer tank is 0.5 meters, the height-to-diameter ratio is 5:1, the material is 304L, and the operating pressure of the buffer tank is 0-1MPa. During operation, the methyl nitrite flow rate, carbon monoxide flow rate, nitrogen flow rate, and hydrogen flow rate values ​​are gradually adjusted according to the operating stage of the pilot plant (start-up, stable operation or emergency stop). During normal operation, they are not 0 at the same time, but the flow rate of a certain flow meter can be set to 0. In the event of an emergency, 0 will be given at the same time.

[0096] The equipment parameters of the esterification unit are as follows: methanol flow rate 0-1.68Kg / h, circulating gas flow rate 0-80SLPM, oxygen flow rate 0-4SLPM, the material of the esterification tower is 304L, the working temperature is 0-200℃, the working pressure is 0-1MPa, and the total NO content is reduced to below 8% through the esterification reaction. During the operation, the methanol flow rate, circulating gas flow rate, and oxygen flow rate are gradually adjusted according to the operating stage of the pilot plant (start-up, stable operation or emergency shutdown). In normal operation, they are not 0 at the same time, but the flow rate of a certain flow meter can be set to 0. In the event of an emergency, 0 will be given at the same time.

[0097] The reactor equipment parameters are as follows: the heat exchange area of ​​the heat exchanger is 0.6m 3 The design maximum temperature is 200℃, the loading volume of methyl formate reactor is 1L, and the operating space velocity is 0~5000h -1 , the hydrogen is reduced to below 100 ppm after passing through the dehydrogenation reactor.

[0098] The parameters of the esterification tower equipment are as follows: The heat exchange area of ​​the heat exchanger is 0.36m 2 , the design pressure of the elution tower is 0.1MPa, and the design temperature is 80℃;

[0099] The parameters of the distillation tower equipment are as follows: the heat exchange area of ​​the preheater is 0.85m 2 The design pressure is 0.4MPa. The first and second distillation towers use 316L, with a height-to-diameter ratio of 50:1, an operating temperature of 0-200℃, a packing volume of 50L, and a heat exchange area of ​​0.36m for the preheater, condenser and cooler. 2 .

[0100] The reactor adopts a tubular reactor, the length of the reactor is 2 meters, the inner diameter of a single tube is 26mm, the material is 316, and the pressure range is 0-5MPa. Its design diagram is as follows Figure 4 shown.

[0101] Example 2

[0102] Using the pilot plant of Example 1, the production method of methyl formate by low-load CO esterification is as follows:

[0103] 1. Check all settings on all hardware devices and control software;

[0104] 2. Open the utility unit and prepare the gas and liquid raw materials (methanol, nitrogen, hydrogen, oxygen, argon, carbon monoxide, methyl nitrite), ensure that the pressure and liquid level are normal, and load 0.5 kg of molded Pd-Cu / (SiC+Al2O3) catalyst into the reactor;

[0105] 3. Turn on the analysis unit and energize all instruments, equipment, heaters, and heating cables; supply cooling water, chilled water, and instrument gas required for the common project; and set all manual and automatic valves to their initial values;

[0106] 4. Check air tightness and start vacuum replacement;

[0107] 5. First introduce nitrogen and turn on the booster unit and elution unit;

[0108] 6. After the booster unit is running stably, introduce carbon monoxide, methyl nitrite and hydrogen and raise the temperature to the reaction temperature. At the same time, closely monitor the temperature, pressure, liquid level, flow rate, composition and other parameters during the reaction until the reactor temperature stabilizes at a certain value; control the methyl nitrite flow rate to 1.0SLPM, the carbon monoxide flow rate to 1.8SLPM; the nitrogen flow rate to 0.2SLPM; and the hydrogen flow rate to 0.8SLPM.

[0109] 7. After the reactor is operating normally, start the esterification unit, introduce methanol and oxygen so that the NO gas in the circulating gas can be regenerated into raw material gas methyl nitrite, and adjust the oxygen and methanol flow rates through the detection of the analysis unit to reduce the NO content at the outlet of the esterification unit to below 8%; control the methanol flow rate of the esterification tower to 0.2Kg / h, the circulating gas flow rate to 45SLPM, the oxygen flow rate to 0.5SLPM, the operating temperature to 50℃, and the working pressure to 0.2Mpa. Control the operating space velocity of the reactor to 2500h -1 , operating temperature is 145℃.

[0110] 8. After the reactor is in normal operation, the content of organic matter in the circulating gas is controlled to be below 2% by detecting the analytical unit and adjusting the temperature and flow rate of cold methanol;

[0111] 9. When the separation unit reaches the preset liquid level, the heating, cooling and feed valves of the corresponding tower can be opened to start the distillation tower; at the same time, the composition of the bottom, inlet and outlet of each distillation tower is detected, and the quality of each product meets the standard by adjusting the reflux ratio, tower top heater and heating temperature.

[0112] 10. When the pilot plant reaches steady-state operation, on the one hand, the methyl formate product can be gradually collected, and the process parameters of each process unit in the pilot plant can be gradually optimized; at the same time, the radial temperature distribution on the catalyst bed in the reactor and the temperature distribution in different axial directions can be measured, and the catalyst performance (selectivity, conversion rate, life) can be examined.

[0113] 11. Through the analysis of the product, it can be known that the chromaticity is <10, the water content is 0.01%, the evaporation residue is 3.4mg / 100ml, the methyl formate content is 97.01%, and the methanol content is 2.54%. All indicators meet the national standard of superior products. The test data of the product is shown in Table 1 below.

[0114] Table 1

[0115]

[0116] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A pilot system for preparing methyl formate by CO esterification, characterized in that: The CO esterification to methyl formate pilot system comprises a methyl nitrite gas pipeline, a nitrogen gas pipeline, a carbon monoxide gas pipeline, a hydrogen gas pipeline, an oxygen gas pipeline, a methanol pipeline, a circulating gas booster unit (1), an esterification tower (2), a preheating tower (3), a reactor (4), a dehydrogenation reactor (5), an elution tower (6), a first distillation tower (7), a dimethyl oxalate storage tank (8), a second distillation tower (9), a third distillation tower (10), a methyl formate storage tank (11), a methylal storage tank (12), a methanol storage tank (13), a purge unit (14), and a tail gas absorption tank (15); The methyl nitrite gas pipeline, the nitrogen gas pipeline, the carbon monoxide gas pipeline, the hydrogen gas pipeline and the circulating gas pipeline are connected to the inlet of the circulating gas boosting unit (1), the outlet of the circulating gas boosting unit (1) and the oxygen gas pipeline are connected to the inlet of the middle and lower ends of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower (2) via a liquid pump; The inlet of the preheater (3) is connected to the outlet of the top of the esterification tower (2), the inlet of the reactor (4) is connected to the outlet of the preheater (3), the inlet of the dehydrogenation reactor (5) is connected to the outlet of the reactor (4), the lower inlet of the elution tower (6) is connected to the outlet of the dehydrogenation reactor (5), the top of the elution tower (6) is directly connected to the inlet of the booster unit (1) and connected to the tail gas absorption tank (15) through the release unit (14); The material inlet of the first distillation tower (7) is connected to the bottom of the elution tower (6) through a feed pump, the bottom outlet of the first distillation tower (7) is connected to the dimethyl oxalate storage tank (8), the material inlet of the second distillation tower (9) is connected to the top outlet of the first distillation tower (7) through a feed pump, the methanol storage tank (13) is connected to the bottom outlet of the second distillation tower (9) through a feed pump, the material inlet of the third distillation tower (10) is connected to the top outlet (9) of the second distillation unit through a feed pump, the top outlet of the third distillation tower (10) is connected to the methyl formate storage tank (11), and the bottom outlet of the third distillation tower (10) is connected to the methyl acetal storage tank (12).

2. The pilot system according to claim 1, characterized in that: The reactor (4) is a tubular reactor with a multi-stage structure design; A plurality of temperature control points are arranged at different axial heights in the reactor (4) to monitor the temperature of each catalyst bed in the reactor (4); The radial distribution position of the temperature sensor in the tube of the reactor (4) is adjustable so as to simultaneously monitor the radial temperature distribution in the catalyst bed; The reactor (4) is connected to the heat transfer oil system by means of a quick-opening flange.

3. A containerized pilot plant for preparing methyl formate by CO esterification, characterized in that: The pilot plant includes a container, a CO esterification to methyl formate pilot system, a utility unit, an automation control unit, and an analysis unit; The CO esterification system for preparing methyl formate, the utility unit, the automation control unit, and the analysis unit are all arranged in a container; The pilot system for preparing methyl formate by CO esterification is selected from the pilot system described in claim 1 or 2.

4. The pilot plant according to claim 3, characterized in that: The utility unit includes a heating circulation system, a cooling water circulation system, a chilled water circulation system, a vacuum pump, and an air compressor; The heating circulation system is connected to the preheater (3), the reactor (4), the first distillation tower (7), the second distillation tower (9), and the third distillation tower (10) through pipelines; the cooling water circulation system is connected to the compressor unit and the heat transfer oil system; the refrigerated water circulation system is connected to the esterification tower (2), the elution tower, and the methyl formate storage tank (11); and the vacuum pump is connected to the esterification tower (2), the reactor (4), and the elution tower (6).

5. The pilot plant according to claim 3, characterized in that: The automation control unit includes a detection unit, a control unit, and an execution unit; Among them, the detection unit includes a remote pressure sensor, a remote liquid level sensor and a remote temperature sensor; the control unit adopts a distributed control system; the execution unit includes pneumatic, electric switching valves, and electric heating.

6. The pilot plant according to claim 3, characterized in that: The analysis unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer; Preferably, the inlet and outlet of the esterification tower (2), the inlet and outlet of the reactor (4), and the top of the elution tower (6) are all connected to an analysis unit for real-time online analysis; Preferably, artificial sampling ports are provided at the top and the bottom of the first distillation tower (7) and the second distillation tower (9).

7. A method for producing methyl formate by CO esterification, characterized in that: The production method adopts the pilot system according to any one of claims 1 or 2; The following steps are involved: The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas booster unit (1) and are boosted, and the boosted mixed gas and oxygen enter the middle and lower ends of the esterification tower (2), and then the methanol pipeline enters the upper end of the esterification tower (2) through a fluid pump, and undergoes an esterification reaction with the mixed gas in the esterification tower (2) to generate methyl nitrite; The gas effluent from the upper end of the esterification tower (2) enters the preheating tower (3) for preheating, and the preheated gas enters the reactor (4) to contact with the catalyst for reaction; the effluent from the lower end of the reactor (4) enters the dehydrogenation reactor (5) for dehydrogenation, and then enters the elution tower (6) for separation, and is absorbed by cold methanol. The liquid product enters the first distillation tower (7) through a liquid pump for gas-liquid separation, the top product of the first distillation tower (7) enters the second distillation tower (9), the bottom product of the first distillation tower (7) enters the dimethyl oxalate storage tank (8), the top product of the second distillation tower (9) enters the third distillation tower (10), the bottom product of the second distillation tower (9) enters the methanol storage tank (13), the top product of the third distillation tower (10) enters the methyl formate storage tank (11), and the bottom product of the third distillation tower enters the methyl acetal storage tank (12).

8. The production method according to claim 8, characterized in that: The operating parameters of the circulating gas booster unit (1) are as follows: methyl nitrite flow rate 0-16 SLPM, carbon monoxide flow rate 0-25 SLPM; nitrogen flow rate 0-30 SLPM; hydrogen flow rate 0-8 SLPM, and the design pressure is 1 MPa; The operating parameters of the esterification tower (2) are as follows: methanol flow rate 0-1.68Kg / h, circulating gas flow rate 0-80SLPM, oxygen flow rate 0-4SLPM, designed operating temperature 0-200°C, and operating pressure 0-1Mpa; The operating parameters of the reactor (4) are as follows: the operating space velocity is 0 to 5000 h -1 , the maximum design temperature is 200℃; The operating parameters of the first distillation tower (7), the second distillation tower (9) and the third distillation tower (10) are as follows: height-to-diameter ratio of 26 to 65:1, operating temperature of 0 to 200°C, and design pressure of 0.4 MPa.

9. A full-process production method for preparing methyl formate by CO esterification, characterized in that: The full-process production method adopts the pilot plant described in any one of claims 3 to 6; The following steps are involved: S1. Check all settings on all hardware devices and control software; S2. Start the utility unit, prepare the gas and liquid raw materials, ensure the pressure and liquid level of each storage tank are normal, and load the catalyst; S3. Turn on the analysis unit and power on all instruments, pumps, heaters, heating cables and other equipment; supply cooling water, chilled water, heat transfer oil and instrument gas required for the common project; and set all manual and automatic valves to initial values; S4. Check air tightness and start vacuum replacement; S5, first introduce nitrogen, and start the circulating gas booster unit (1) and the elution tower (6); S6, after the circulating gas booster unit (1) is stably operating, carbon monoxide, methyl nitrite and hydrogen are introduced, and the temperature is raised to the reaction temperature, while monitoring the temperature, pressure, liquid level, flow rate, composition and other process parameters of each process unit in the system until the reactor (4) operates normally; S7. After the reactor (4) operates normally, the esterification tower (2) is opened to allow the nitric oxide in the circulating gas to be regenerated into the raw material gas methyl nitrite; S8. When the elution tower (6) reaches a preset liquid level, the first distillation tower (7), the second distillation tower (9) and the third distillation tower (10) can be started, and the heating and feeding of the corresponding towers can be started to ensure stable operation of the distillation towers. S9. When the pilot plant reaches steady-state operation, on the one hand, the methyl formate product is gradually collected, and on the other hand, the process parameters of each process unit in the pilot plant are gradually collected and optimized.

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