A dehydration method of N-formylmorpholine with cyclic spacer hydrocarbon

Abstract

A dehydration method for N-formylmorpholine plus circulating interval hydrocarbon comprises a fractionating tower for rectifying water-containing N-formylmorpholine; a vacuum pumping device for controlling the pressure in a dehydration system; a cooler for preventing water from being carried in the vacuum pumping device; a feed pipeline is connected to one side of the fractionating tower, a steam pipeline is connected to the lower part of the fractionating tower, and the steam pipeline is connected to a low-pressure steam device; a cooler and a water separation and reflux device are connected to the upper part of the fractionating tower, and the cooler and the water separation and reflux device are communicated through a pipeline; the cooler and the water separation and reflux device are both connected to a vacuum pumping pipeline, and the vacuum pumping pipeline is connected to the vacuum pumping device; a reflux regulating valve group is arranged on the pipeline between the water separation and reflux device and the fractionating tower; the method has the advantages of simple operation, low operating cost, low operating temperature, low enterprise energy consumption, and effective fractionation of water-containing N-formylmorpholine.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, in particular to a dehydration method of N-formylmorpholine with a cyclic spacer hydrocarbon. Background Art

[0002] N-Formylmorpholine (NFM) is an excellent extraction solvent in industry. It has high selectivity and solubility, is non-corrosive, has low toxicity, low viscosity, moderate boiling point and freezing point, good chemical stability and thermal stability, and is easy to operate stably. It is widely used in processes such as aromatic extraction, butene and butane separation (i.e. butene concentration technology) and natural gas desulfurization. As a major producer and consumer of aromatics, my country has dozens of industrial units that use aromatic extraction technology using NFM as solvent. At present, the domestic process for synthesizing NFM is mainly based on the acylation method, among which the acylation reaction of formic acid and morpholine to synthesize NFM is the most economical and feasible. The process requires the use of a reaction distillation tower with 100 theoretical plates, and the feed is fed between the 30th and 40th theoretical plates for reaction; the water produced by the reaction is evaporated from the top of the tower, and the product NFM is taken out from the bottom of the tower, and then further distilled and purified. The process is complicated and difficult to operate. It is difficult to operate the system smoothly when the load is low, and due to the electronic induction effect between NFM and water molecules, the two are miscible and difficult to separate. For N-formylmorpholine manufacturers, they need to stop production to deal with N-formylmorpholine returned by customers. The amount returned is small and discontinuous, which is a waste of the production capacity of the device. Summary of the invention

[0003] In order to solve the above problems and overcome the shortcomings of the prior art, the present invention provides a dehydration method of N-formylmorpholine plus circulating spacer hydrocarbon which is simple to operate, has low operating cost, low operating temperature, low enterprise energy consumption, and can effectively fractionate water-containing N-formylmorpholine.

[0004] To achieve the above object, the present invention provides a dehydration system for N-formylmorpholine plus circulating spacer hydrocarbon, comprising a fractionation tower for rectifying water-containing N-formylmorpholine;

[0005] A vacuum device for controlling the pressure in the dehydration system;

[0006] A cooler to prevent water from entering the vacuum device;

[0007] A feed pipeline is connected to one side of the fractionation tower, a steam pipeline is connected to the lower part of the fractionation tower, and the steam pipeline is connected to a low-pressure steam device; a cooler and a water separation and reflux device are connected to the upper part of the fractionation tower, and the cooler and the water separation and reflux device are connected through a pipeline; the cooler and the water separation and reflux device are both connected to a vacuum pipeline, and the vacuum pipeline is connected to a vacuum device;

[0008] A reflux regulating valve group is arranged on the pipeline between the water separation reflux device and the distillation tower.

[0009] Furthermore, the fractionation tower is filled with a mixture of aqueous N-formylmorpholine and pure benzene.

[0010] Furthermore, a material pipe is connected to the lower part of the distillation tower, and the other end of the material pipe is connected to a storage tank.

[0011] Furthermore, the lower part of the distillation tower is connected to a condensate water pipe network.

[0012] Furthermore, the cooler is connected with a return pipe for returning hot water and a supply pipe for supplying cold water.

[0013] Furthermore, the water diversion and reflux device includes a level gauge for detecting the liquid level.

[0014] Furthermore, a drain pipe is connected to the lower part of the water diversion and reflux device.

[0015] Furthermore, the feed pipeline includes an N-formylmorpholine feed pipe and a pure benzene feed pipe.

[0016] The present invention also provides a dehydration method, which comprises the following steps:

[0017] Step 1: injecting aqueous N-formylmorpholine into the fractionation tower through an N-formylmorpholine feed pipe;

[0018] Step 2: injecting pure benzene into the fractionation tower through a pure benzene feed pipe;

[0019] Step 3: Lead 1.0MPa steam to the fractionation tower through the steam pipeline and the low-pressure steam device, and slowly heat up the system at a rate of less than or equal to 25°C / h;

[0020] Step 4: When the pressure at the top of the distillation tower rises, start the vacuum device according to the operating procedures, and slowly pump the negative pressure of the system to 30KPa and keep it stable;

[0021] Step 5: When the temperature at the top of the fractionation tower rises, circulating water is introduced to the cooler through the upper water pipe to control the cooler outlet temperature to be less than or equal to 45°C;

[0022] Step 6: When the liquid level of the water diversion reflux device rises to 50%, start the reflux regulating valve group to reflux to the top of the tower by self-pressure, and control the top temperature of the tower to be between 95℃ and 100℃;

[0023] Step 7: Control the steam flow rate at the bottom of the fractionation tower and control the bottom temperature at 150°C-160°C;

[0024] Step 8: Observe the dehydration situation through the on-site interface of the water diversion and reflux device, and keep the interface meter less than or equal to 30%;

[0025] Step 9: When the level of the water diversion reflux device stops rising, the system dehydration is basically completed, and samples are taken from the bottom of the fractionation tower to analyze the water content in N-formylmorpholine;

[0026] Step 10: After the test is qualified, the steam flow rate at the bottom of the tower is slowly reduced, the system temperature is lowered to 60°C, and the N-formylmorpholine dehydrated in the distillation tower is transferred to the storage tank through the material pipe.

[0027] Further, in step 2, the proportion of pure benzene in the mixture is 23%;

[0028] In step 4, the vacuum pump is configured as a liquid ring vacuum pump;

[0029] In step nine, samples are taken and analyzed for structure twice in succession, and the sample is qualified if the water content is less than or equal to 0.5%.

[0030] The beneficial effects of the present invention are:

[0031] The dehydration method of N-formylmorpholine plus circulating spacer hydrocarbon provided by the invention has the advantages of simple operation, low operating cost, low operating temperature, low enterprise energy consumption, and effective fractionation of water-containing N-formylmorpholine. The enterprise can regenerate N-formylmorpholine by using its own device, and does not need to return it to the manufacturer for processing and payment of regeneration costs including transportation, etc., and adopts a reduced pressure operation to reduce the operating temperature to 160 DEG C, so as to protect N-formylmorpholine from decomposition at high temperature; at the same time, the boiling point of water is reduced, so that it is easier to boil and volatilize, which is conducive to separation; the equipment and facilities are less modified, the investment is small, and the process route and the operation mode are mainly adjusted. The operation is simple, the operating cost is low, the enterprise can transform and implement it by itself, the temperature is low, and the enterprise energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Attached Figure 1 It is a schematic diagram of the structure of the present invention;

[0033] Attached Figure 2 It is a schematic diagram of the structure of an embodiment of the present invention;

[0034] In the attached figure: 1. distillation tower, 2. cooler, 3. water diversion reflux device, 4. reboiler, 5. feed pipeline, 6. reflux regulating valve group, 7. drain pipe, 8. vacuum pipeline, 9. material pipe, 11. steam pipeline, 12. condensate water network, 21. return pipe, 22. water supply pipe, 31. level meter. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention more clear, the following will be combined with the appended claims of the present invention. Figure 1 and attached Figure 2 , the present invention is described in more detail.

[0036] The dehydration system of N-formylmorpholine plus circulating interval hydrocarbon provided by the present invention comprises a fractionation tower 1 for rectifying water-containing N-formylmorpholine; a vacuum pumping device for controlling the pressure in the dehydration system; a cooler 2 for preventing water from being carried in the vacuum pumping device; a feed pipeline 5 is connected to one side of the fractionation tower 1, a steam pipeline 11 is connected to the lower part of the fractionation tower 1, and the steam pipeline 11 is connected to a low-pressure steam device; a cooler 2 and a water separation and reflux device 3 are connected to the upper part of the fractionation tower 1, and the cooler 2 and the water separation and reflux device 3 are connected through a pipeline; the cooler 2 and the water separation and reflux device 3 are both connected to a vacuum pumping pipeline 8, and the vacuum pumping pipeline 8 is connected to A vacuum pump is connected; a reflux regulating valve group 6 is arranged on the pipeline between the water-dividing and reflux device 3 and the fractionating tower 1; the fractionating tower 1 is filled with a mixture of water-containing N-formylmorpholine and pure benzene; a material pipe 9 is connected to the lower part of the fractionating tower 1, and the other end of the material pipe 9 is connected to a storage tank; a condensate water pipe network 12 is connected to the lower part of the fractionating tower 1; a return pipe 21 for returning hot water and a water supply pipe 22 for feeding cold water are connected to the cooler 2; the water-dividing and reflux device 3 includes a level gauge 31 for detecting the liquid level height; a drain pipe 7 is connected to the lower part of the water-dividing and reflux device 3; and a feed pipeline 5 includes an N-formylmorpholine feed pipe and a pure benzene feed pipe.

[0037] The present invention also provides a dehydration method, which comprises the following steps:

[0038] Step 1: injecting aqueous N-formylmorpholine into the fractionation tower 1 through the N-formylmorpholine feed pipe;

[0039] Step 2: injecting pure benzene into the fractionation tower 1 through the pure benzene feed pipe;

[0040] Step 3: 1.0 MPa steam is introduced to the fractionation tower 1 through the steam pipeline 11 and the low-pressure steam device, and the system is slowly heated up, and the heating rate is less than or equal to 25°C / h;

[0041] Step 4: When the pressure at the top of the distillation tower 1 rises, start the vacuum device according to the operating procedures, and slowly pump the negative pressure of the system to 30KPa and keep it stable;

[0042] Step 5: When the temperature at the top of the fractionation tower 1 rises, circulating water is introduced to the cooler 2 through the upper water pipe 22, and the outlet temperature of the cooler 2 is controlled to be less than or equal to 45° C.;

[0043] Step 6: When the liquid level of the water diversion reflux device 3 rises to 50%, the reflux regulating valve group 6 is started to reflux to the top of the tower by self-pressure, and the temperature of the top of the tower is controlled at 95°C-100°C;

[0044] Step 7: Control the steam flow rate at the bottom of the fractionation tower 1 and control the bottom temperature at 150°C-160°C;

[0045] Step 8: Observe the dehydration situation through the on-site interface of the water diversion and reflux device 3, and keep the interface meter 31 less than or equal to 30%;

[0046] Step 9: When the level of the water diversion reflux device 3 stops rising, the system dehydration is basically completed, and a sample is taken from the bottom of the fractionation tower 1 to analyze the water content in N-formylmorpholine;

[0047] Step 10: After the test is qualified, the steam flow rate at the bottom of the tower is slowly reduced, the system temperature is lowered to 60° C., and the N-formylmorpholine dehydrated in the fractionation tower 1 is transferred to the storage tank through the material pipe 9.

[0048] In step 2, the proportion of pure benzene in the mixture is 23%;

[0049] In step 4, the vacuum pump is configured as a liquid ring vacuum pump;

[0050] In step nine, samples are taken and analyzed for structure twice in succession, and the sample is qualified if the water content is less than or equal to 0.5%.

[0051] One embodiment of the present invention is as follows:

[0052] The fractionation tower 1 is set as a regeneration tower E511, and the regeneration tower E511 is connected with an N-formylmorpholine feed pipe and a pure benzene feed pipe for inputting N-formylmorpholine and pure benzene; the lower part of the regeneration tower E511 is connected with a steam pipeline 11, and a low-pressure steam device is connected through the steam pipeline 11, and steam is transported to the bottom of the regeneration tower E511 by the low-pressure steam device to control the temperature of the bottom of the regeneration tower E511; at the same time, it is connected with a condensate pipe network 12; the bottom of the regeneration tower E511 is also connected with a material pipe 9, and a storage tank is connected through the material pipe 9 for storing dehydrated N-formylmorpholine. A reboiler 4 can also be set at the bottom of the regeneration tower E511, and heat exchange is performed through the reboiler 4, and the vaporized two phases after heat exchange re-enter the regeneration tower E511.

[0053] The top of the regeneration tower is connected to a cooler 2 and a water-dividing reflux device 3 through two pipelines. The cooler 2 is connected to a water supply pipe 22 for cold water and a water return pipe 21 for hot water reflux, and is cooled by heat exchange of circulating water. The water-dividing reflux device 3 is set as a reflux buffer tank, and a level gauge 31 is set on the reflux buffer tank for observing the liquid level in the reflux buffer tank; the lower part of the reflux buffer tank is connected to a drain pipe 7 for discharging sewage; the upper part of the reflux buffer tank is connected to the vacuum device through a vacuum line 8, and the cooler 2 is also connected to the vacuum device through a vacuum line 8; the vacuum device is set as a liquid ring vacuum pump.

[0054] According to the above structure, the specific dehydration operation steps are as follows:

[0055] Step 1: Inject water-containing N-formylmorpholine into the regeneration tower E511 through the N-formylmorpholine feed pipe until the liquid level rises to 1.0m, with a volume of about 3.87m³;

[0056] Step 2: Inject pure benzene into the regeneration tower E511 through the pure benzene feed pipe until the liquid level rises to 1.4m, with a volume of about 1.16m³, accounting for about 23% of N-formylmorpholine;

[0057] Step 3: 1.0MPa steam is introduced to the regeneration tower E511 through the steam pipeline 11 and the low-pressure steam device, and the system is slowly heated up, with a heating rate of less than or equal to 25°C / h;

[0058] Step 4: When the pressure at the top of the regeneration tower E511 rises, start the liquid ring vacuum pump according to the operating procedures, and slowly pump the negative pressure of the system to 30KPa and keep it stable;

[0059] Step 5: When the temperature at the top of the regeneration tower E511 rises, circulating water is introduced to the cooler 2 through the upper water pipe 22, and the outlet temperature of the cooler 2 is controlled to be less than or equal to 45°C to prevent the vacuum system from carrying liquid;

[0060] Step 6: When the liquid level in the reflux buffer tank rises to 50%, the reflux regulating valve group 6 is started to reflux to the top of the tower by self-pressure, and the temperature of the top of the tower is controlled at 95°C-100°C;

[0061] Step 7: Control the steam flow rate at the bottom of the regeneration tower E511 and control the bottom temperature at 150°C-160°C;

[0062] Step 8: Observe the dehydration situation through the on-site interface of the reflux buffer tank, and keep the interface meter 31 less than or equal to 30% to prevent the removed water from flowing back into the system again;

[0063] Step 9: When the level of the reflux buffer tank stops rising, it means that the system dehydration is basically completed. Samples are taken from the bottom of the regeneration tower E511 to analyze the water content in N-formylmorpholine. If the water content is less than or equal to 0.5% after two consecutive sampling analyses, it is qualified;

[0064] Step 10: After the test is qualified, the steam flow rate at the bottom of the tower is slowly reduced, the system temperature is lowered to 60° C., and the N-formylmorpholine dehydrated in the regeneration tower E511 is transferred to the storage tank through the material pipe 9;

[0065] In the initial stage of use, pay attention to the N content of the intermediate product of the crude benzene hydrogenation unit to prevent excessive content from affecting product quality.

[0066] The moisture content test results before and after dehydration are as follows:

[0067] N-Formylmorpholine water content test data before dehydration:

[0068]

[0069] N-Formylmorpholine water content test data after dehydration:

[0070]

[0071] After dehydration, N-formylmorpholine was put into the aromatics extraction process, and the test results on the impact on product quality were as follows:

[0072]

[0073] The test results show that the dehydration method provided by the present invention can effectively complete the dehydration operation of N-formylmorpholine, and after the dehydrated N-formylmorpholine is put into the aromatics extraction process, the aromatics extraction process can be effectively completed.

[0074] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for dehydrating N-formylmorpholine with a circulating spacer hydrocarbon, applied to a dehydration system for N-formylmorpholine with a circulating spacer hydrocarbon, characterized in that: The following steps are involved: Step 1: injecting aqueous N-formylmorpholine into the fractionation tower (1) through the N-formylmorpholine feed pipe; Step 2: injecting pure benzene into the fractionation tower (1) through a pure benzene feed pipe; Step 3: introducing 1.0 MPa steam to the fractionation tower (1) through the steam pipeline (11) and the low-pressure steam device, and slowly heating the system at a heating rate of less than or equal to 25° C. / h; Step 4: When the pressure at the top of the distillation tower (1) rises, start the vacuum pumping device according to the operating procedures, and slowly pump the negative pressure of the system to 30KPa and keep it stable; Step 5: When the temperature at the top of the fractionation tower (1) rises, circulating water is introduced to the cooler (2) through the upper water pipe (22), and the outlet temperature of the cooler (2) is controlled to be less than or equal to 45° C.; Step 6: When the liquid level of the water diversion reflux device (3) rises to 50%, the reflux regulating valve group (6) is started to reflux to the top of the tower by self-pressure, and the temperature of the top of the tower is controlled at 95°C-100°C; Step 7: Control the steam flow rate at the bottom of the fractionation tower (1) to control the bottom temperature at 150°C-160°C; Step 8: Observe the dehydration situation through the on-site interface of the water diversion and reflux device (3), and keep the interface meter (31) less than or equal to 30%; Step 9: When the level of the water separation and reflux device (3) stops rising, the system dehydration is basically completed, and a sample is taken from the bottom of the fractionation tower (1) to analyze the water content in N-formylmorpholine; Step 10: After the test is qualified, the steam flow rate at the bottom of the tower is slowly reduced, the system temperature is lowered to 60° C., and the N-formylmorpholine dehydrated in the fractionation tower (1) is transferred to the storage tank through the material pipe (9); The dehydration system of N-formylmorpholine plus circulating spacer hydrocarbon comprises: A fractionation column (1) for rectifying aqueous N-formylmorpholine; A vacuum device for controlling the pressure in the dehydration system; A cooler (2) for preventing water from entering the vacuum device; A feed pipeline (5) is connected to one side of the fractionation tower (1); a steam pipeline (11) is connected to the lower part of the fractionation tower (1); and the steam pipeline (11) is connected to a low-pressure steam device; a cooler (2) and a water separation and reflux device (3) are connected to the upper part of the fractionation tower (1); and the cooler (2) and the water separation and reflux device (3) are connected via a pipeline; and the cooler (2) and the water separation and reflux device (3) are both connected to a vacuum pipeline (8); and the vacuum pipeline (8) is connected to a vacuum device; A reflux regulating valve group (6) is provided on the pipeline between the water separation reflux device (3) and the fractionation tower (1); The lower part of the fractionation tower (1) is connected to a material pipe (9), and the other end of the material pipe (9) is connected to a storage tank; The water diversion and reflux device (3) comprises a level gauge (31) for detecting the liquid level.

2. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: In step 2, the proportion of pure benzene in the mixture is 23%; In step 4, the vacuum pump is configured as a liquid ring vacuum pump; In step nine, samples are taken and analyzed for structure twice in succession, and the sample is qualified if the water content is less than or equal to 0.5%.

3. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: The fractionation tower (1) is filled with a mixture of aqueous N-formylmorpholine and pure benzene.

4. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: The lower part of the fractionation tower (1) is connected to a condensate pipe network (12).

5. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: The cooler (2) is connected to a water return pipe (21) for returning hot water and a water supply pipe (22) for supplying cold water.

6. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: The lower part of the water diversion and reflux device (3) is connected to a drainage pipe (7).

7. The dehydration method of N-formylmorpholine with a circulating spacer hydrocarbon according to claim 1, characterized in that: The feed pipeline (5) includes an N-formylmorpholine feed pipe and a pure benzene feed pipe.

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