Furfural reduced pressure vaporization device and method in furan production

Abstract

The invention discloses a furfural reduced pressure vaporization device in furan production, which comprises a vaporization tower, a hydrogen storage tank and a buffer unit, the top of the vaporization tower is provided with a furfural raw material inlet and a vaporized furfural gas and hydrogen mixed gas outlet; the buffer unit comprises a front buffer tank and a rear buffer tank, a mixed gas outlet of the vaporizing tower is connected with the front buffer tank through a pipeline, mixed gas is buffered by the front buffer tank and then is connected to a vacuum pump through a pipeline, and an outlet of the vacuum pump is connected to the rear buffer tank; the middle part of the vaporizing tower is connected with a hydrogen storage tank through a pipeline; and a regulating valve and a flow meter are arranged on the pipeline. According to the method, the pressure reduction mode is adopted, the furfural can be heated and vaporized without reaching the boiling point of the furfural, polymerization of the furfural is greatly reduced, the forced circulation heater is adopted, the retention time of the furfural in the tube nest of the heat exchanger can be shortened, and the furfural is prevented from coking on the inner wall of the tube nest to block the heat exchanger.

Description

Technical Field

[0001] The invention relates to the technical field of furan production, and in particular to a device and method for reducing the pressure and vaporizing furfural in furan production. Background Art

[0002] As one of the important intermediates in organic chemical production, furan is in increasing demand in the market, and the deep processing and preparation of furfural needs to be solved urgently. There are two methods for furan preparation by decarbonylation of furfural: gas phase method and liquid phase method. The gas phase method is well received by Guangzhou and Shenzhen because it can realize industrial continuous production, the catalyst is easy to regenerate, and high boiling point solvent is not required. However, due to the high boiling point of furfural itself and the characteristics of coking and polymerization at high temperature, a large amount of furfural is wasted in the industrial production process.

[0003] In the industrial production process of furfural decarbonylation to furan, reducing the coking and polymerization of furfural during the vaporization process has a great impact on reducing the production cost. At present, the main method of furfural vaporization in China is to vaporize furfural directly in a general tube or jacket vaporizer. This method consumes a lot of steam and if it is not well controlled, it is easy to cause furfural to coke and polymerize in the vaporizer, resulting in steam waste and increasing production costs. Moreover, after furfural cokes, it is very easy to cause the vaporizer and pipeline to be blocked, which brings inconvenience to production and causes system fluctuations.

[0004] This device uses a decompression method to reduce the boiling point of furfural, so that furfural can be vaporized without heating to an excessively high temperature, saving steam while reducing the coking and polymerization of furfural. At the same time, hydrogen is introduced into the middle of the vaporization tower to reduce the partial pressure of furfural in the gas phase and the vaporization temperature of furfural. In addition, this device uses a forced circulation reboiler to reduce the time furfural stays in the reboiler and prevent furfural from clogging the heat exchanger after coking. The vaporization tower bottom liquid is controlled by a regulating valve and continuously discharged to prevent the heavy components in the tower bottom from enriching and causing furfural coking. Summary of the invention

[0005] In order to solve the problems mentioned in the above background technology, the present invention provides a furfural reduced pressure vaporization device and method in furan production.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A furfural decompression vaporization device in furan production comprises a vaporization tower, a hydrogen storage tank and a buffer unit, wherein the top of the vaporization tower is provided with a furfural raw material inlet and an outlet for a mixed gas of vaporized furfural gas and hydrogen;

[0008] The buffer unit includes a front buffer tank and a rear buffer tank. The mixed gas outlet of the vaporization tower is connected to the front buffer tank through a pipeline. After the mixed gas is buffered in the front buffer tank, it is connected to the vacuum pump through a pipeline, and the vacuum pump outlet is connected to the rear buffer tank. The middle part of the vaporization tower is connected to the hydrogen storage tank through a pipeline, and a regulating valve and a flow meter are provided on the pipeline.

[0009] Preferably, the front buffer tank and the rear buffer tank are connected via a reflux pipe, and a regulating valve is provided for adjusting the vacuum degree of the front vaporization tower.

[0010] Preferably, the bottom discharge port of the vaporization tower is connected to a circulation pump, and the outlet of the circulation pump is connected to a shell-and-tube heat exchanger, which is heated by medium-pressure steam and is provided with a regulating valve and a flow meter for adjusting the evaporation amount of furfural.

[0011] Preferably, another outlet of the circulation pump is connected to a temporary storage tank for furfural waste liquid through a pipeline, and is provided with a regulating valve for controlling the removal of heavy components at the bottom of the vaporization tower.

[0012] Preferably, the vacuum pump includes a base, and a piston cylinder and a mounting bracket are respectively fixed to the top of the base, and a horizontal reciprocating drive mechanism is installed on the mounting bracket. The output end of the horizontal reciprocating drive mechanism extends into the piston cylinder and is fixed to the piston inside the piston cylinder. A vacuum port and an air outlet are respectively provided on the side of the piston cylinder away from the mounting bracket, and a one-way valve is installed on both the vacuum port and the air outlet, and the air outlet is connected to the rear buffer tank.

[0013] Preferably, the vacuum pump is also equipped with a filter, and the filter is provided with an air inlet end and an air outlet end, the air inlet end is connected to the front buffer tank, and the air outlet end is connected to the air suction port of the piston cylinder.

[0014] Preferably, the horizontal reciprocating drive mechanism includes a turntable and a connecting rod, a toggle rod is fixed on the turntable, the connecting rod is rotatably mounted on the mounting bracket, and a rectangular opening is opened on the connecting rod, the toggle rod passes through the connecting rod through the rectangular opening, and an arc-shaped rack is fixed at the bottom end of the connecting rod.

[0015] Preferably, a horizontal moving rod is movably mounted on the bracket, a top end of the horizontal moving rod is provided with meshing teeth corresponding to the arc-shaped rack, and one end of the horizontal moving rod is fixed to the piston.

[0016] A method for reducing pressure and vaporizing furfural in furan production comprises the following steps:

[0017] Step S1: Furfural is pumped into a vaporizer through a pump and fed from the top of the vaporizer. The low-temperature furfural is used to absorb the heavy components in the gas phase, and finally the liquid level of the vaporizer is controlled at % to %.

[0018] Step S2: Turn on the reciprocating vacuum pump and control the pressure at the top of the vaporization tower to a certain value through the regulating valve;

[0019] Step S3: The liquid in the bottom of the vaporization tower is pumped into the shell-and-tube heat exchanger through a circulation pump. The material enters from the bottom of the shell-and-tube heat exchanger, passes through the tubes, and exits from the top of the shell-and-tube heat exchanger to enter the vaporization tower. The shell of the shell-and-tube heat exchanger is heated by medium-pressure steam to vaporize the furfural and generate steam. The steam returns to the tower and goes up with the hydrogen to escape from the top of the vaporization tower after the low-temperature furfural absorbs the heavy components. The liquid returns to the bottom of the tower and continues to circulate.

[0020] Step S4: As evaporation proceeds, the furfural content at the bottom of the tower gradually decreases, and the heavy components are enriched at the bottom of the tower and need to be removed regularly.

[0021] The industrial production of furan from furfural decarbonylation in gas phase belongs to continuous production. The stability of furfural vaporization has a great influence on the stability of the system. If the furfural vaporization fluctuates too much, it may cause system fluctuations, affect production, and even cause catalyst deactivation. In the present invention, a steam regulating valve and a precision flowmeter are installed for monitoring to achieve smooth furfural vaporization and prevent the fluctuation of furfural vaporization flow caused by steam fluctuations; the inlet and outlet of the vacuum pump of the present invention are both provided with buffer tanks, and the buffer tanks are controlled by regulating valves to achieve the stability of the pressure of the vaporization tower and the outlet flow; the present invention adopts a forced circulation reboiler to reduce the residence time of furfural in the reboiler while heating, and prevent furfural from coking in the reboiler and causing pipeline blockage; the present invention adopts a continuous external discharge method for the vaporization tower bottom liquid to control the furfural content in the tower bottom to be not less than 90%, which will not cause excessive furfural consumption, and can prevent the heavy components from being enriched in the tower bottom, and prevent the phenomenon of furfural coking and polymerization, thereby ensuring the stability of production.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Because furfural is a heat-sensitive material, it is easy to polymerize under high temperature conditions, resulting in raw material loss and increased production costs. Moreover, furfural is very easy to coke and carbonize under high temperature, resulting in blockage of pipelines and circulating pumps, malfunctions, and affecting the stability of the system. In the present invention, a decompression method is adopted so that furfural can be heated and vaporized without reaching the boiling point of furfural, which greatly reduces the polymerization of furfural. In addition, a forced circulation heater is adopted in the present invention, which can reduce the time furfural stays in the heat exchanger tubes and prevent furfural from coking on the inner wall of the tubes and clogging the heat exchanger.

[0024] 2. The present invention reduces the partial pressure of furfural vapor in the mixed gas by introducing hydrogen into the vaporization tower, which can also reduce the temperature required for furfural vaporization and reduce the polymerization of furfural under high temperature conditions, thereby achieving the purpose of cost saving.

[0025] 3. As the temperature rises, furfural is continuously vaporized, and the heavy components in the vaporization tower bottom are continuously enriched, which are easily carbonized and coked, causing pipeline blockage. The present invention adopts a method of continuous external discharge and control of the furfural content in the bottom to prevent furfural from carbonizing and coking, thereby ensuring the stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 is a flow chart of the present invention;

[0028] Figure 2 It is a front view of the vacuum pump of the present invention;

[0029] Figure 3 A three-dimensional diagram of the filter of the present invention;

[0030] Figure 4 A first-view stereoscopic view of the vacuum pump of the present invention;

[0031] Figure 5 for Figure 4 Schematic diagram of the cutaway of the piston cylinder;

[0032] Figure 6 A second perspective view of the vacuum pump of the present invention;

[0033] In the figure: 1 vaporization tower, 2 hydrogen storage tank, 3 heat exchanger, 4 front buffer tank, 5 furfural waste liquid temporary storage tank, 6 vacuum pump, 601 base, 602 base, 603 turntable, 6031 toggle rod, 604 connecting rod, 6041 rectangular opening, 6042 arc rack, 605 horizontal moving rod, 6051 meshing teeth, 606 piston cylinder, 6061 piston, 6062 air outlet, 6063 air suction port, 607 motor, 6071 motor reducer, 7 filter, 701 air inlet end, 702 air outlet end, 8 circulation pump, 9 rear buffer tank. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] Reference Figure 1-6 , a furfural decompression vaporization device in furan production, comprising a vaporization tower 1, a hydrogen storage tank 2 and a buffer unit, wherein the top of the vaporization tower 1 is provided with a furfural raw material inlet and an outlet for a mixed gas of vaporized furfural gas and hydrogen;

[0037] The buffer unit includes a front buffer tank 4 and a rear buffer tank 9. The mixed gas outlet of the vaporizer 1 is connected to the front buffer tank 4 through a pipeline. After the mixed gas is buffered by the front buffer tank 4, it is connected to the vacuum pump 6 through a pipeline. The outlet of the vacuum pump 6 is connected to the rear buffer tank 9. The middle part of the vaporizer 1 is connected to the hydrogen storage tank 2 through a pipeline, and a regulating valve and a flow meter are provided on the pipeline.

[0038] The front buffer tank 4 and the rear buffer tank 9 are connected via a reflux pipe, and a regulating valve is provided for adjusting the vacuum degree of the front vaporization tower.

[0039] The bottom outlet of the vaporization tower 1 is connected to a circulation pump 8, and the outlet of the circulation pump 8 is connected to a shell-and-tube heat exchanger 3. The heat exchanger 3 is heated by medium-pressure steam and is provided with a regulating valve and a flow meter for adjusting the evaporation amount of furfural.

[0040] Among them, another outlet of the circulation pump 8 is connected to the furfural waste liquid temporary storage tank 5 through a pipeline, and is provided with a regulating valve control for removing the heavy components at the bottom of the vaporization tower 1.

[0041] Example 2

[0042] Reference Figure 1-6 The difference between this embodiment and embodiment 1 is that the vacuum pump 6 includes a base 601, a piston cylinder 606 and a mounting bracket 602 are respectively fixed to the top of the base 601, a horizontal reciprocating drive mechanism is installed on the mounting bracket 602, the output end of the horizontal reciprocating drive mechanism extends into the piston cylinder 606 and is fixed to the piston 6061 inside the piston cylinder 606, and a suction port 6063 and a gas outlet 6062 are respectively provided on the side of the piston cylinder 606 away from the mounting bracket 602, and a one-way valve is installed on the suction port 6063 and the gas outlet 6062, and the gas outlet 6062 is communicated with the rear buffer tank 9;

[0043] When the horizontal reciprocating mechanism drives the piston 6061 to move horizontally back and forth, due to the existence of the one-way valve, when the piston 6061 moves toward the vacuum port 6063 and one end of the gas outlet 6062, the one-way valve at the gas outlet 6062 allows the gas to pass through, and the one-way valve at the vacuum port 6063 is closed. At this time, the gas inside the piston cylinder 606 is discharged, and the reverse movement draws the gas into the piston cylinder 606 through the vacuum port 6063. This cycle can achieve the purpose of continuous one-way gas extraction, thereby adjusting the gas pressure in the vaporization tower 1.

[0044] The vacuum pump 6 is also equipped with a filter 7, which is provided with an air inlet end 701 and an air outlet end 702, wherein the air inlet end 701 is connected to the front buffer tank 4, and the air outlet end 702 is connected to the air extraction port 6063 of the piston cylinder 606;

[0045] The solid impurities in the gas can be filtered out by the filter 7, thereby ensuring the purity of the gas and preventing the solid impurities from entering the front buffer tank (4) and the rear buffer tank (9).

[0046] The horizontal reciprocating drive mechanism includes a rotating disk 603 and a connecting rod 604. A toggle rod 6031 is fixed on the rotating disk 603. The connecting rod 604 is rotatably mounted on the mounting bracket 602. A rectangular opening 6041 is provided on the connecting rod 604. The toggle rod 6031 passes through the connecting rod 604 through the rectangular opening 6041. An arc-shaped rack 6042 is fixed to the bottom end of the connecting rod 604. A horizontal moving rod 605 is also movably mounted on the bracket 602. A meshing tooth 6051 corresponding to the arc-shaped rack 6042 is provided at the top end of the horizontal moving rod 605. One end of the horizontal moving rod 605 is fixed to the piston 6061. The rotating disk 603 is driven by a motor 607. The motor 607 is equipped with a motor reducer 6071.

[0047] When the turntable 603 is driven to rotate by the motor 607, the toggle rod 6031 will slide in the rectangular opening 6041 and push the connecting rod 604 to swing back and forth, and then the interaction between the arc-shaped rack 6042 and the top meshing tooth 6051 of the horizontal moving rod 605 will drive the horizontal moving rod 605 to move back and forth horizontally, thereby driving the vacuum pump 6 to work. The structure is simple, the transmission is efficient, and it is easy to inspect and maintain.

[0048] Example 3

[0049] A method for reducing pressure and vaporizing furfural in furan production comprises the following steps:

[0050] Step S1: Furfural is pumped into the vaporization tower 1, fed from the top of the vaporization tower 1, and the low-temperature furfural is used to absorb the heavy components in the gas phase, and finally the liquid level of the vaporization tower 1 is controlled at 40-50%;

[0051] Step S2: Turn on the reciprocating vacuum pump 6 and control the pressure at the top of the vaporization tower 1 to a certain value through the regulating valve;

[0052] Step S3: The kettle liquid of the vaporizer 1 is pumped into the shell-and-tube heat exchanger 3 through the circulation pump 8. The material enters from the bottom of the shell-and-tube heat exchanger 3, passes through the tubes, and comes out from the top of the shell-and-tube heat exchanger 3 to enter the vaporizer 1. The shell of the shell-and-tube heat exchanger 3 is heated by medium-pressure steam to gasify the furfural and generate steam. The steam returns to the tower and goes up together with the hydrogen to escape from the top of the vaporizer 1 after absorbing the heavy components through the low-temperature furfural. The liquid returns to the bottom of the tower and continues to circulate.

[0053] Step S4: As evaporation proceeds, the furfural content at the bottom of the tower gradually decreases, and the heavy components are enriched at the bottom of the tower and need to be removed regularly.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] The control method of the present invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by technicians in this field. The provision of power is also common knowledge in this field. The present invention is mainly used to protect mechanical devices, so the present invention will no longer explain the control method and circuit connection in detail.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A furfural vacuum vaporization device in furan production, characterized in that: The invention comprises a vaporization tower (1), a hydrogen storage tank (2) and a buffer unit, wherein the top of the vaporization tower (1) is provided with a furfural raw material inlet and an outlet for a mixed gas of vaporized furfural gas and hydrogen; The buffer unit comprises a front buffer tank (4) and a rear buffer tank (9); the mixed gas outlet of the vaporizer (1) is connected to the front buffer tank (4) via a pipeline; after the mixed gas is buffered in the front buffer tank (4), it is connected to a vacuum pump (6) via a pipeline; the outlet of the vacuum pump (6) is connected to the rear buffer tank (9); the middle part of the vaporizer (1) is connected to a hydrogen storage tank (2) via a pipeline, and a regulating valve and a flow meter are provided on the pipeline.

2. A furfural reduced pressure vaporization device in furan production according to claim 1, characterized in that: The front buffer tank (4) and the rear buffer tank (9) are connected via a reflux pipeline and are provided with a regulating valve for adjusting the vacuum degree of the front vaporization tower.

3. A furfural reduced pressure vaporization device in furan production according to claim 1, characterized in that: The bottom discharge port of the vaporization tower (1) is connected to a circulation pump (8), and the outlet of the circulation pump (8) is connected to a shell-and-tube heat exchanger (3). The heat exchanger (3) is heated by medium-pressure steam and is provided with a regulating valve and a flow meter for adjusting the evaporation amount of furfural.

4. A furfural reduced pressure vaporization device in furan production according to claim 3, characterized in that: Another outlet of the circulation pump (8) is connected to the furfural waste liquid temporary storage tank (5) through a pipeline and is provided with a regulating valve for controlling the removal of heavy components at the bottom of the vaporization tower (1).

5. The furfural reduced pressure vaporization device in furan production according to claim 1, characterized in that: The vacuum pump (6) comprises a base (601), the top of which is respectively fixed with a piston cylinder (606) and a mounting bracket (602), the mounting bracket (602) being mounted with a horizontal reciprocating drive mechanism, the output end of which extends into the piston cylinder (606) and is fixed to a piston (6061) inside the piston cylinder (606), a suction port (6063) and an air outlet (6062) are respectively provided on the side of the piston cylinder (606) away from the mounting bracket (602), both the suction port (6063) and the air outlet (6062) being mounted with a one-way valve, and the air outlet (6062) is connected to a rear buffer tank (9).

6. A furfural reduced pressure vaporization device in furan production according to claim 5, characterized in that: The vacuum pump (6) is also equipped with a filter (7), and the filter (7) is provided with an air inlet end (701) and an air outlet end (702), the air inlet end (701) is connected to the front buffer tank (4), and the air outlet end (702) is connected to the air suction port (6063) of the piston cylinder (606).

7. The furfural reduced pressure vaporization device in furan production according to claim 5, characterized in that: The horizontal reciprocating drive mechanism comprises a rotating disk (603) and a connecting rod (604), wherein a toggle rod (6031) is fixed on the rotating disk (603), the connecting rod (604) is rotatably mounted on the mounting bracket (602), and a rectangular opening (6041) is provided on the connecting rod (604), the toggle rod (6031) passes through the connecting rod (604) through the rectangular opening (6041), and an arc-shaped rack (6042) is fixed at the bottom end of the connecting rod (604).

8. The furfural reduced pressure vaporization device in furan production according to claim 7, characterized in that: A horizontal moving rod (605) is also movably mounted on the bracket (602), and a meshing tooth (6051) corresponding to the arc-shaped rack (6042) is provided at the top of the horizontal moving rod (605), and one end of the horizontal moving rod (605) is fixed to the piston (6061).

9. A method for reducing furfural pressure and vaporizing in furan production, which is implemented by a device for reducing furfural pressure and vaporizing in furan production as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1: Furfural is pumped into a vaporizer (1) from the top of the vaporizer (1), and the low-temperature furfural is used to absorb the heavy components in the gas phase, and finally the liquid level of the vaporizer (1) is controlled at 40-50%; Step S2: turning on the reciprocating vacuum pump (6) and controlling the pressure at the top of the vaporization tower (1) to a certain value through the regulating valve; Step S3: The kettle liquid of the vaporization tower (1) is pumped into the shell-and-tube heat exchanger (3) through the circulation pump (8), and the material enters from the bottom of the shell-and-tube heat exchanger (3), passes through the tubes, and comes out from the top of the shell-and-tube heat exchanger (3) to enter the vaporization tower (1). The shell of the shell-and-tube heat exchanger (3) is heated by medium-pressure steam to vaporize the furfural and generate steam. The steam returns to the tower and goes up together with the hydrogen to escape from the top of the vaporization tower (1) after the low-temperature furfural absorbs the heavy components. The liquid returns to the bottom of the tower and continues to circulate. Step S4: As evaporation proceeds, the furfural content at the bottom of the tower gradually decreases, and the heavy components are enriched at the bottom of the tower and need to be removed regularly.

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