Device and method for treating non-condensable gas in distillation process of high freezing point system

Abstract

The present application discloses a device for treating non-condensable gas during the distillation process of a high-freezing-point system. The top vapor outlet of the distillation tower is connected to the shell-side gas inlet of the first cooler and the second cooler after passing through the shell side of the first condenser and the second condenser in sequence; the shell-side gas outlets of the first cooler and the second cooler are both connected to the feed inlet of the desublimation trap, and the shell-side gas outlet of the second cooler is connected to the feed inlet of the desublimation trap; the exhaust port at the top of the desublimation trap is connected to the vacuum port of the main vacuum pump via a vacuum buffer tank; the shell-side liquid discharge ports at the bottom of the first condenser and the second condenser are both connected to the reflux tank; the low-level tank is connected to the high-level tank via a solvent pump, and the shell-side liquid inlet of the first cooler and the second cooler of the high-level tank is connected to the shell-side liquid outlet of the first cooler and the second cooler. The present application also discloses a method for treating non-condensable gas during the distillation process of a high-freezing-point system. The present application can recycle high-freezing-point components to avoid damage to the main vacuum pump.

Description

Technical Field

[0001] The invention relates to a device and method for treating non-condensable gas in the distillation process of a high-freezing-point system. Background Art

[0002] Distillation is a unit operation widely used in chemical production to separate liquid mixtures. Depending on the operating pressure of the distillation tower, distillation can be divided into pressure distillation, atmospheric distillation, and vacuum distillation. High vacuum distillation is generally used in industry to separate mixtures with high boiling points and heat-sensitive components. In high vacuum distillation, light components in the mixture and air leaking into the distillation system form non-condensable gases under high vacuum conditions. These gases are then processed in a condenser and cooler before being pumped out of the distillation system by a vacuum pump.

[0003] During the vacuum distillation process of high-freezing-point systems, the high-freezing-point components contained in the non-condensable gas will bring great difficulties to the distillation. The reason is that during the distillation process of high-freezing-point systems, the overhead vapor condenses in the overhead condenser. At high temperatures, the saturated vapor pressure of the high-freezing-point components is relatively high. After passing through the condenser, the non-condensable gas containing a small amount of high-freezing-point components flows along the gas phase pipeline to the vacuum pump. It will condense and precipitate in the low-temperature equipment and pipelines, forming sublimated solids. The sublimated solids condense on the inner walls of the equipment and pipelines. In severe cases, it will cause blockage of the equipment and pipelines. Some of the sublimated solids will enter the vacuum system and damage the vacuum pump, affecting the stable operation of the distillation unit. Summary of the Invention

[0004] To solve the above problems, the present invention first proposes a device for treating non-condensable gas in the distillation process of a high-freezing-point system, which includes a distillation tower, a primary condenser, a secondary condenser, a reflux tank, a first cooler, a second cooler, a low-level tank, a high-level tank, a sublimation collector, a vacuum buffer tank, a main vacuum pump, and a solvent pump. In terms of height, the bottoms of the primary condenser and the secondary condenser are both higher than the top of the reflux tank, the bottoms of the first cooler and the second cooler are both higher than the top of the low-level tank, and the tops of the first cooler and the second cooler are both lower than the bottom of the high-level tank.

[0005] The top vapor outlet of the distillation tower is connected to the shell-side gas phase inlet of the primary condenser via a first pipeline, the shell-side gas phase outlet of the primary condenser is connected to the shell-side gas phase inlet of the secondary condenser via a second pipeline, and the shell-side gas phase outlet of the secondary condenser leads to two branch pipes, which are respectively a first air inlet branch pipe and a second air inlet branch pipe, wherein the first air inlet branch pipe is connected to the shell-side gas phase inlet of the first cooler, and the second air inlet branch pipe is connected to the shell-side gas phase inlet of the second cooler, a first air inlet valve is installed on the first air inlet branch pipe, and a second air inlet valve is installed on the second air inlet branch pipe;

[0006] The shell-side gas phase outlet of the first cooler is connected to the feed inlet at the lower part of the desublimation trap via a first exhaust branch pipe, and the shell-side gas phase outlet of the second cooler is connected to the feed inlet at the lower part of the desublimation trap via a second exhaust branch pipe. A first exhaust valve is installed on the first exhaust branch pipe, and a second exhaust valve is installed on the second exhaust branch pipe.

[0007] The exhaust port on the top of the desublimation trap is connected to the vacuum port of the main vacuum pump through the vacuum buffer tank;

[0008] The shell-side drain ports at the bottom of the primary condenser and the secondary condenser are both connected to the reflux tank;

[0009] The material outlet of the low-level tank is connected to the inlet of the solvent pump, and the outlet of the solvent pump is connected to the material inlet of the high-level tank. The material outlet at the bottom of the high-level tank leads to two liquid inlet branches, which are respectively connected to the shell-side liquid inlet of the first cooler and the second cooler. A liquid inlet valve is installed on each liquid inlet branch;

[0010] The material inlet of the low-level tank leads to two liquid outlet branches, which are respectively connected to the shell-side liquid outlet of the first cooler and the second cooler. A liquid outlet valve is installed on each liquid outlet branch.

[0011] In the present application, the primary condenser, the secondary condenser, the first cooler and the second cooler are preferably horizontal shell and tube heat exchangers.

[0012] Using this application, the condensation causes the top steam of the distillation tower to be condensed first in the shell side of the first condenser and the second condenser, so that most of the high freezing point components in the top steam are liquefied and recovered, and a small amount of high freezing point components enter the first cooler or the second cooler. The first cooler and the second cooler in this application are in a parallel relationship and can be used alternately. The high freezing point components can be condensed into desublimation materials in the first cooler and the second cooler and deposited in the shell side of the first cooler and the second cooler. By alternating the first cooler and the second cooler, the desublimation materials in the first cooler and the second cooler can be dissolved and recovered alternately while ensuring the normal operation of the distillation system. Finally, the desublimation trap is used to adsorb the exhaust gas of the first cooler and the second cooler to completely remove the high freezing point components contained in the top steam, thereby preventing the high freezing point components contained in the top steam from entering the main vacuum pump, causing damage to the main vacuum pump and affecting the normal operation of the distillation device.

[0013] Furthermore, an auxiliary vacuum pump is included. The vacuum port of the auxiliary vacuum pump leads to two vacuum branches, which are respectively connected to the shell-side vacuum ports of the first cooler and the second cooler. Preferably, the shell-side vacuum port and the shell-side liquid inlet of the first cooler are connected to the same interface, and the shell-side vacuum port and the shell-side liquid inlet of the second cooler are connected to the same interface.

[0014] The auxiliary vacuum pump is used to evacuate the first cooler and the second cooler so that the pressure inside the first cooler and the second cooler reaches their own working pressure, thereby reducing the pressure fluctuation of the vacuum device when the coolers are switched.

[0015] Furthermore, an exhaust pipe is provided on the top of the reflux tank, and the exhaust pipe is connected to the second pipe through the top of the second pipe.

[0016] The exhaust pipe at the top of the reflux tank is connected to the second pipeline, so that the gas phase pressure in the reflux tank is the same as the pressure in the second pipeline, which is conducive to the condensate in the first condenser and the second condenser flowing into the reflux tank by gravity.

[0017] Furthermore, in order to maintain the temperature of the solvent in the low-level tank and the high-level tank so as to smoothly dissolve and recover the desublimated materials in the first cooler and the second cooler, heaters are provided in the low-level tank and the high-level tank.

[0018] Specifically, the desublimation trap is a packed tower. The packing within the packed tower can be ceramic rings, saddle rings, or ball rings. The packing in the packed tower allows the desublimation material carried in the exhaust gases from the first and second coolers to adhere to the packing. If necessary, the desublimation trap can be removed from the distillation apparatus. Low-pressure steam is introduced from the top of the trap to dissolve the desublimation material adsorbed on the packing surface and remove it from the bottom of the trap.

[0019] Furthermore, to prevent the high-freezing-point components in the non-condensable gases within each pipeline from prematurely solidifying due to encountering the cooler pipe walls and adhering to the pipe inner walls, potentially blocking the pipes, the first pipeline, the second pipeline, the first intake branch pipe, the second intake branch pipe, the first exhaust branch pipe, and the second exhaust branch pipe are all equipped with heat tracing pipes. The temperature of the heating medium within the heat tracing pipes is higher than the freezing point of the high-freezing-point components, thereby maintaining the high-freezing-point components in the non-condensable gases within each of the aforementioned pipelines in a liquid or gaseous state. The exhaust pipe at the top of the return pipe is also equipped with a heat tracing pipe.

[0020] Secondly, the present application also provides a method for treating non-condensable gas in the distillation process of a high freezing point system, which is performed using the device for treating non-condensable gas in the distillation process of a high freezing point system described in any one of the above items, and the treatment method comprises the following steps:

[0021] (1) A high freezing point system enters a distillation tower for distillation, and overhead steam is discharged from the top of the distillation tower. The overhead steam is sequentially condensed by a primary condenser and a secondary condenser. The condensed tail gas generated after condensation is discharged from the secondary condenser, passes through a first cooler to form a primary tail gas, and the primary tail gas passes through a desublimation trap to form a secondary tail gas. The secondary tail gas passes through a vacuum buffer tank and is discharged by a main vacuum pump;

[0022] The cooling medium in the primary condenser and the secondary condenser is preferably an organic heat carrier, and specifically heat transfer oil, such as alkyl diphenyl ether type, mineral type heat transfer oil, etc. can be selected.

[0023] The coolant of the first cooler and the second cooler can be cooling water, the temperature of the cooling water is lower than the freezing point temperature of the high freezing point component, so as to enable the high freezing point component in the condensed tail gas to desublimate to form desublimated material;

[0024] The condensate generated by the condensation of the tower top steam in the primary condenser and the secondary condenser enters the reflux tank; when the condensed tail gas passes through the first cooler, the high freezing point component is cooled to desublimated material, and the desublimated material is deposited in the shell side of the first cooler;

[0025] When the first-stage tail gas passes through the desublimation collector, the desublimation materials carried in the first-stage tail gas are adsorbed in the desublimation collector;

[0026] (2) Close the first air inlet valve and the first air outlet valve, open the second air inlet valve and the second air outlet valve, and allow the condensed tail gas to pass through the second cooler to form the primary tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material in the shell side of the first cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the first cooler is completed;

[0027] (3) Open the first air inlet valve and the first air outlet valve, close the second air inlet valve and the second air outlet valve, so that the condensed tail gas passes through the first cooler to form the primary tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material in the shell side of the second cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the second cooler is completed;

[0028] (4) Repeat steps (2) and (3) until the distillation of the high freezing point system is completed.

[0029] In this application, a method of stepwise condensation of high-freezing-point components is adopted to recover high-freezing-point components contained in the overhead vapor of a distillation tower stepwise. First, the high-freezing-point components in the overhead vapor are liquefied using a primary condenser and a secondary condenser. Then, the high-freezing-point components in the condensed tail gas are desublimed using a first cooler and a second cooler to form solid desublimed materials. These desublimed materials are deposited in the shell side of the first cooler or the second cooler. Since the first cooler and the second cooler are used alternately, the desublimed materials deposited in the first cooler and the second cooler can be dissolved and recovered using a solvent. The trace desublimed materials carried by the first tail gas are adsorbed by the desublimation trap, thereby completing the removal of the high-freezing-point components in the overhead vapor and preventing the high-freezing-point components from entering the main vacuum pump and damaging the main vacuum pump, which would affect the stable operation of the distillation unit. The desublimed materials adsorbed in the desublimation trap are heated by steam to dissolve the desublimed materials and then discharged from the bottom of the desublimation trap for recovery.

[0030] Furthermore, to fully reduce the content of high-freezing-point components in the overhead vapor of the distillation tower, the outlet temperature of the condensate in the primary condenser is the same as the operating temperature of the top of the distillation tower, and the outlet temperature of the condensate in the secondary condenser is 20-50°C higher than the freezing point temperature of the high-freezing-point components. Under the above-mentioned temperature control, the overhead vapor is first condensed and liquefied in the primary condenser, and the condensate enters the reflux tank through the inner shell-side outlet of the primary condenser. In the secondary condenser, the outlet temperature of the condensate is set to be 20-50°C higher than the freezing point temperature of the high-freezing-point components, but still below the vaporization temperature of the high-freezing-point components. In this way, most of the high-freezing-point components in the overhead vapor can be condensed and liquefied and enter the reflux tank, thereby significantly reducing the content of high-freezing-point components in the condensed tail gas discharged from the secondary condenser.

[0031] Furthermore, after the desublimation material in the first cooler or the second cooler is dissolved and absorbed, the first cooler or the second cooler is evacuated to bring the pressure therein to its operating pressure. Specifically, the first cooler is evacuated to bring the pressure therein to its own operating pressure, or the second cooler is evacuated to bring the pressure therein to its own operating pressure.

[0032] Evacuate the cooler to the working pressure to reduce the pressure fluctuation of the vacuum device when the cooler is switched.

[0033] Specifically, the solvent in the low-level tank is an inert solvent with a low boiling point. Specifically, the inert solvent is an alcohol, and water or an alcohol-water solution. Selecting a low-boiling-point alcohol solvent or an alcohol-water solvent is advantageous for recovering the solvent from the mixture after dissolving the high-freezing-point component. Specifically, the alcohol can be methanol, ethanol or isopropanol.

[0034] Compared with the existing technology, the overall beneficial effects of this application are as follows:

[0035] 1. Set up a two-stage condenser. The outlet temperature of the condensate of the first condenser is the tower top temperature under the operating pressure. The outlet temperature of the second condensate does not exceed the solidification temperature of the high freezing point component by 50°C. Due to the supercooling effect of the second condenser, the saturated vapor pressure of the high freezing point component is reduced, reducing its content in the non-condensable gas.

[0036] Second, two parallel coolers are used and operated alternately. Cooling water is passed through the cooler pipes to make the temperature of the cooling water lower than the freezing point of the high freezing point component. The high freezing point component in the non-condensable gas is further cooled in the cooler and condensed to precipitate powdery condensed materials.

[0037] 3. Using hot solvent from the solvent tank to dissolve the high freezing point components precipitated in the condenser and recover them will help reduce the discharge of solid and liquid waste, increase the recovery rate of distillation products, and clean the cooler.

[0038] 4. Use the desublimation collector to absorb the trace desublimation materials carried in the first-stage tail gas, completely eliminating the enrichment of desublimation materials in the pipeline and the impact on the main vacuum pump.

[0039] 5. Heating measures shall be taken for pipelines involving non-condensable gases. The heating temperature shall be higher than the freezing point to eliminate the sublimation and enrichment of high freezing point components on the inner surface of the pipeline due to low temperature, thereby preventing pipeline blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0041] Example 1

[0042] The following first describes the treatment device for non-condensable gas in the distillation process of high freezing point system. Figure 1 The processing device includes a distillation tower 1, a primary condenser 2, a secondary condenser 3, a reflux tank 4, a first cooler 5, a second cooler 6, a low-level tank 7, a high-level tank 8, a desublimation collector 91, a vacuum buffer tank 92, a main vacuum pump 93, an auxiliary vacuum pump 94, and a solvent pump 74. The primary condenser, the secondary condenser, the first cooler, and the second cooler all use horizontal shell and tube heat exchangers.

[0043] In the height direction, the bottoms of the first-stage condenser 2 and the second-stage condenser 3 are higher than the top of the reflux tank 4, the bottoms of the first cooler 5 and the second cooler 6 are higher than the top of the low-level tank 7, and the tops of the first cooler 5 and the second cooler 6 are lower than the bottom of the high-level tank 8.

[0044] The top steam outlet 12 of the distillation tower 1 is connected to the first shell-side gas phase inlet 21 of the first-stage condenser 2 through the first pipeline 13, and the first shell-side gas phase outlet 22 of the first-stage condenser is connected to the second shell-side gas phase inlet 31 of the second-stage condenser 3 through the second pipeline 24. The second shell-side gas phase outlet 32 ​​of the second-stage condenser leads to two branches, which are a first air inlet branch 33 and a second air inlet branch 35 respectively, wherein the first air inlet branch is connected to the third shell-side gas phase inlet 51 of the first cooler 5, and the second air inlet branch is connected to the fourth shell-side gas phase inlet 61 of the second cooler 6. A first air inlet valve 34 is installed on the first air inlet branch, and a second air inlet valve 36 is installed on the second air inlet branch.

[0045] The third shell-side gas phase outlet 53 of the first cooler 5 is connected to the feed inlet 911 at the lower portion of the desublimation trap 91 via a first exhaust branch pipe 55. The fourth shell-side gas phase outlet 63 of the second cooler 6 is connected to the feed inlet 911 at the lower portion of the desublimation trap 91 via a second exhaust branch pipe 65. A first exhaust valve 56 is installed on the first exhaust branch pipe, and a second exhaust valve 66 is installed on the second exhaust branch pipe. In this embodiment, the desublimation trap is specifically a packed tower, and the packing is specifically ball rings.

[0046] The exhaust port 912 at the top of the sublimation trap 91 is connected to the inner cavity of the vacuum buffer tank through the top inlet 921 of the vacuum buffer tank 92. The vacuum port of the main vacuum pump 93 is connected to the vacuum suction port 922 at the top of the vacuum buffer tank 92. A recovery port 913 is provided at the bottom of the sublimation trap 91, and a sewage outlet 923 is provided at the bottom of the vacuum buffer tank.

[0047] The first shell-side liquid drain port 23 at the bottom of the primary condenser 2 and the second shell-side liquid drain port 38 at the bottom of the secondary condenser are both connected to the reflux tank.

[0048] An exhaust pipe 43 is provided on the top of the reflux tank 4. The exhaust pipe 43 extends upward over the second pipe and then bends downward, and then is connected to the second pipe from the top of the second pipe.

[0049] The first shell-side gas phase inlet 21, the first shell-side gas phase outlet 22 and the first shell-side liquid drain 23 are all connected to the shell side of the primary condenser 2. The second shell-side gas phase inlet 31, the second shell-side gas phase outlet 32 ​​and the second shell-side liquid drain 38 are all connected to the shell side of the secondary condenser 3.

[0050] The third shell-side gas phase inlet 51 and the third shell-side gas phase outlet 53 are both connected to the shell side of the first cooler 5 , and the fourth shell-side gas phase inlet 61 and the fourth shell-side gas phase outlet 63 are both connected to the shell side of the second cooler 6 .

[0051] The first material outlet 72 of the low-level tank 7 is connected to the inlet of the solvent pump 74. The outlet of the solvent pump 74 is connected to a return liquid pipe 75 and a recovery pipe 77. A return liquid valve 76 is installed on the return liquid pipe 75, and a recovery valve 78 is installed on the recovery pipe. The return liquid pipe 75 is connected to the second material inlet 81 of the high-level tank 8, and a solvent addition port 73 is provided at the top of the low-level tank.

[0052] The material outlet 82 at the bottom of the high-level tank 8 leads to two liquid inlet branches, which are a first liquid inlet branch 83 and a second liquid inlet branch 85. A first liquid inlet valve 84 is installed on the first liquid inlet branch 83, and a second liquid inlet valve 86 is installed on the second liquid inlet branch 85.

[0053] The first liquid inlet branch pipe 83 is connected to the third shell-side liquid inlet 52 of the first cooler 5 , and the second liquid inlet branch pipe 85 is connected to the fourth shell-side liquid inlet 62 of the second cooler 6 .

[0054] Two liquid outlet branches are led from the first material inlet 71 of the low-level tank 7. These two branches are a first liquid outlet branch 57 and a second liquid outlet branch 67. A first liquid outlet valve 58 is installed on the first liquid outlet branch 57, and a second liquid outlet valve 68 is installed on the second liquid outlet branch 67. The first liquid outlet branch 57 is connected to the third shell-side liquid outlet 54 at the bottom of the first cooler, and the second liquid outlet branch 67 is connected to the fourth shell-side liquid outlet 64 at the bottom of the second cooler.

[0055] The third shell-side liquid inlet 52 and the third shell-side liquid outlet 54 are both connected to the shell-side of the first cooler. The fourth shell-side liquid inlet 62 and the fourth shell-side liquid outlet 64 are both connected to the shell-side of the second cooler.

[0056] The vacuum port of the auxiliary vacuum pump 94 leads to two vacuum branch pipes, namely a first vacuum branch pipe 95 and a second vacuum branch pipe 97. A first on-off valve 96 is installed on the first vacuum branch pipe 95, and a second on-off valve 98 is installed on the second vacuum branch pipe 97. The first vacuum branch pipe 95 is connected to the first shell-side vacuum port of the first cooler, and the second vacuum branch pipe 97 is connected to the second shell-side vacuum port of the second cooler.

[0057] The first shell-side vacuum port is connected to the shell-side of the first cooler, and the second shell-side vacuum port is connected to the shell-side of the second cooler. In this embodiment, the third shell-side liquid inlet 52 and the first shell-side vacuum port are connected by the same connection port, that is, the third shell-side liquid inlet 52 also serves as the first shell-side vacuum port. The fourth shell-side liquid inlet 62 and the second shell-side vacuum port are connected by the same connection port, that is, the fourth shell-side liquid inlet 62 also serves as the second shell-side vacuum port. In other words, the shell-side vacuum port and the shell-side liquid inlet of the first cooler are connected by the same connection port, and the shell-side vacuum port and the shell-side liquid inlet of the second cooler are connected by the same connection port.

[0058] In order to ensure the temperature of the solvent in the low-level tank and the high-level tank, heaters are provided in the low-level tank and the high-level tank. Specifically, in this embodiment, the heaters are coil-type heating tubes and are heated by steam.

[0059] In order to maintain the temperature of the gas in each pipeline, the first pipeline, the second pipeline, the first air intake branch pipe, the second air intake branch pipe, the first exhaust branch pipe, the second exhaust branch pipe and the tank exhaust pipe at the top of the reflux are all equipped with heating pipes.

[0060] Example 2

[0061] A method for treating non-condensable gas during the distillation of a high freezing point dodecanediamine system.

[0062] In this embodiment, the high freezing point component is dodecanediamine, which has a freezing point of 69°C.

[0063] The treatment method is carried out using the above-mentioned device for treating non-condensable gas in the distillation process of the high freezing point system, and the treatment method comprises the following steps:

[0064] (1) The high freezing point material enters the distillation tower 1 through the raw material inlet 11 for distillation, and the top steam is discharged from the top of the distillation tower. The top steam is condensed in turn through the primary condenser and the secondary condenser. The condensed tail gas generated after condensation is discharged from the secondary condenser and then passes through the first cooler to form the primary tail gas. The primary tail gas passes through the desublimation collector to form the secondary tail gas. The secondary tail gas passes through the vacuum buffer tank and is discharged by the main vacuum pump.

[0065] The condensate generated by the condensation of the top steam in the first condenser and the second condenser enters the reflux tank; when the condensed tail gas passes through the first cooler, the high freezing point component is cooled into desublimated material, and the desublimated material is deposited in the shell side of the first cooler.

[0066] When the primary tail gas passes through the desublimation collector, the desublimation materials carried in the primary tail gas are adsorbed in the desublimation collector.

[0067] (2) Close the first air inlet valve and the first air exhaust valve, open the second air inlet valve and the second air exhaust valve, so that the condensed tail gas passes through the second cooler to form the first-level tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material through the shell side of the first cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the first cooler is completed.

[0068] (3) Open the first air inlet valve and the first air exhaust valve, close the second air inlet valve and the second air exhaust valve, so that the condensed tail gas passes through the first cooler to form the first-level tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material through the shell side of the second cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the second cooler is completed.

[0069] (4) Repeat steps (2) and (3) until the distillation of the high freezing point system is completed.

[0070] After the dissolution and absorption of the desublimated material in the first cooler or the second cooler is completed, the first cooler or the second cooler is evacuated to make the pressure in the first cooler or the second cooler reach its working pressure.

[0071] Low-pressure steam is used to dissolve and remove the desublimation materials in the desublimation trap.

[0072] The material collected in the reflux tank 4 can be discharged through the drain pipe 44 at the bottom of the reflux tank, part of which is refluxed to the distillation tower and part of which is used as product.

[0073] A solvent inlet 73 is provided at the top of the low-level tank for pouring solvent into the low-level tank.

[0074] In this embodiment, the distillation tower has a top pressure of 2 kPa and a top temperature of 160°C. Thermal oil is used as the cooling medium for the primary and secondary condensers, flowing through the tubes of each condenser. The thermal oil temperature is 95°C. The flow rate of the cooling medium in the primary condenser is controlled to maintain the outlet temperature of the condensate therein at 160°C. The flow rate of the cooling medium in the secondary condenser is controlled to maintain the outlet temperature of the condensate therein at 120°C.

[0075] Cooling water is used as the cooling medium of the first cooler and the second cooler, and the temperature of the cooling water is 32°C.

[0076] use water The temperature of the solvent in the low-level tank and the high-level tank was maintained at 90°C.

[0077] When the solvent in the low-level tank is saturated with absorption, the recovery valve 78 is opened to discharge the saturated solvent in the low-level tank for separation and recovery.

[0078] When the desublimation material adsorbed in the desublimation trap needs to be recovered, low-pressure steam is introduced through the steam pipe 914 at the top of the desublimation trap to dissolve the desublimation material, and the dissolved desublimation material is discharged from the recovery port 913 for recovery.

[0079] Example 3

[0080] A method for treating non-condensable gas during the distillation of a high freezing point dodecanediamine system.

[0081] In this embodiment, the high freezing point component is dodecanediamine, which has a freezing point of 69°C.

[0082] This embodiment is basically the same as the embodiment, except that:

[0083] In this embodiment, the distillation tower has a top pressure of 0.9 kPa and a top temperature of 150°C. Thermal oil is used as the cooling medium for the primary and secondary condensers, flowing through the tubes of each condenser. The thermal oil temperature is 95°C. The flow rate of the cooling medium in the primary condenser is controlled so that the outlet temperature of the condensate in the primary condenser is 150°C. The flow rate of the cooling medium in the secondary condenser is controlled so that the outlet temperature of the condensate in the secondary condenser is 110°C.

[0084] Cooling water is used as the cooling medium of the first cooler and the second cooler, and the temperature of the cooling water is 32°C.

[0085] An ethanol aqueous solution was used as the solvent in the low-level tank, and the temperature of the solvent in the low-level tank and the high-level tank was maintained at 60°C.

[0086] Example 4

[0087] A method for treating non-condensable gas during the distillation of a high freezing point decanediamine system.

[0088] In this embodiment, the high freezing point component is decanediamine, which has a freezing point of 62-63°C.

[0089] This embodiment is basically the same as the embodiment, except that:

[0090] In this embodiment, the distillation tower has a top pressure of 1.6 kPa and a top temperature of 142°C. Thermal oil is used as the cooling medium for the primary and secondary condensers, flowing through the tubes of each condenser. The thermal oil temperature is 95°C. The flow rate of the cooling medium in the primary condenser is controlled to maintain the outlet temperature of the condensate therein at 137°C. The flow rate of the cooling medium in the secondary condenser is controlled to maintain the outlet temperature of the condensate therein at 110°C.

[0091] Cooling water is used as the cooling medium of the first cooler and the second cooler, and the temperature of the cooling water is 32°C.

[0092] Ethanol was used as the solvent in the low-level tank, and the temperature of the solvent in the low-level tank and the high-level tank was maintained at 70°C.

[0093] Example 5

[0094] A method for treating non-condensable gas during the distillation of a high freezing point decanediamine system.

[0095] In this embodiment, the high freezing point component is decanediamine, which has a freezing point of 62-63°C.

[0096] This embodiment is basically the same as the embodiment, except that:

[0097] In this embodiment, the distillation tower has a top pressure of 2 kPa and a top temperature of 150°C. Thermal oil is used as the cooling medium for the primary and secondary condensers, flowing through the tubes of each condenser. The thermal oil temperature is 95°C. The flow rate of the cooling medium in the primary condenser is controlled to maintain the outlet temperature of the condensate therein at 150°C. The flow rate of the cooling medium in the secondary condenser is controlled to maintain the outlet temperature of the condensate therein at 100°C.

[0098] Cooling water is used as the cooling medium of the first cooler and the second cooler, and the temperature of the cooling water is 32°C.

[0099] Methanol was used as the solvent in the low-level tank, and the temperature of the solvent in the low-level tank and the high-level tank was maintained at 70°C.

Claims

1. A device for treating non-condensable gas in the distillation process of a high freezing point system, characterized in that: It includes a distillation tower, a primary condenser, a secondary condenser, a reflux tank, a first cooler, a second cooler, a low-level tank, a high-level tank, a desublimation trap, a vacuum buffer tank, a main vacuum pump, and a solvent pump; in the height direction, the bottoms of the primary condenser and the secondary condenser are higher than the top of the reflux tank, the bottoms of the first cooler and the second cooler are higher than the top of the low-level tank, and the tops of the first cooler and the second cooler are lower than the bottom of the high-level tank; The top vapor outlet of the distillation tower is connected to the shell-side gas phase inlet of the primary condenser via a first pipeline, the shell-side gas phase outlet of the primary condenser is connected to the shell-side gas phase inlet of the secondary condenser via a second pipeline, and the shell-side gas phase outlet of the secondary condenser leads to two branch pipes, which are respectively a first air inlet branch pipe and a second air inlet branch pipe, wherein the first air inlet branch pipe is connected to the shell-side gas phase inlet of the first cooler, and the second air inlet branch pipe is connected to the shell-side gas phase inlet of the second cooler, a first air inlet valve is installed on the first air inlet branch pipe, and a second air inlet valve is installed on the second air inlet branch pipe; The shell-side gas phase outlet of the first cooler is connected to the feed inlet at the lower part of the desublimation trap via a first exhaust branch pipe, and the shell-side gas phase outlet of the second cooler is connected to the feed inlet at the lower part of the desublimation trap via a second exhaust branch pipe. A first exhaust valve is installed on the first exhaust branch pipe, and a second exhaust valve is installed on the second exhaust branch pipe. The exhaust port on the top of the desublimation trap is connected to the vacuum port of the main vacuum pump through the vacuum buffer tank; The shell-side drain ports at the bottom of the primary condenser and the secondary condenser are both connected to the reflux tank; The material outlet of the low-level tank is connected to the inlet of the solvent pump, and the outlet of the solvent pump is connected to the material inlet of the high-level tank. The material outlet at the bottom of the high-level tank leads to two liquid inlet branches, which are respectively connected to the shell-side liquid inlet of the first cooler and the second cooler. A liquid inlet valve is installed on each liquid inlet branch; The material inlet of the low-level tank leads to two liquid outlet branches, which are connected to the shell-side liquid outlet of the first cooler and the second cooler respectively. A liquid outlet valve is installed on each liquid outlet branch; The desublimation collector is a packed tower. The packing in the packed tower is specifically ceramic rings, saddle rings or ball rings. The packing in the packed tower is used to make the desublimation materials carried in the exhaust gas of the first cooler and the second cooler adhere to the packing.

2. The processing device according to claim 1, characterized in that The invention also comprises an auxiliary vacuum pump, the vacuum port of the auxiliary vacuum pump leads to two vacuum branches, and the two vacuum branches are connected to the shell side vacuum port of the first cooler and the second cooler respectively.

3. The processing device according to claim 1, characterized in that An exhaust pipe is provided on the top of the reflux tank, and the exhaust pipe is connected to the second pipeline through the top of the second pipeline.

4. The processing device according to claim 1, characterized in that Heaters are provided in both the low-level tank and the high-level tank.

5. The processing device according to claim 1, characterized in that The first pipeline, the second pipeline, the first air intake branch pipe, the second air intake branch pipe, the first exhaust branch pipe and the second exhaust branch pipe are all provided with a heating pipe.

6. A method for treating non-condensable gas in the distillation process of a high freezing point system, characterized by: The method is carried out using the device for treating non-condensable gas in the distillation process of a high freezing point system according to any one of claims 1 to 5, and the method comprises the following steps: (1) The high freezing point system enters the distillation tower for distillation, and the top steam is discharged from the top of the distillation tower. The top steam is condensed in turn through the primary condenser and the secondary condenser. The condensed tail gas generated after condensation is discharged from the secondary condenser and then passes through the first cooler to form the primary tail gas. The primary tail gas passes through the desublimation trap to form the secondary tail gas. The secondary tail gas passes through the vacuum buffer tank and is discharged by the main vacuum pump; The condensate generated by the condensation of the tower top steam in the primary condenser and the secondary condenser enters the reflux tank; when the condensed tail gas passes through the first cooler, the high freezing point components are cooled to desublimated materials, which are deposited in the shell side of the first cooler; When the first-stage tail gas passes through the desublimation collector, the desublimation materials carried in the first-stage tail gas are adsorbed in the desublimation collector; (2) Close the first air inlet valve and the first air outlet valve, open the second air inlet valve and the second air outlet valve, and allow the condensed tail gas to pass through the second cooler to form the first-level tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material through the shell side of the first cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the first cooler is completed; (3) Open the first air inlet valve and the first air outlet valve, close the second air inlet valve and the second air outlet valve, so that the condensed tail gas passes through the first cooler to form the first-level tail gas; the solvent in the low-level tank is pumped into the high-level tank through the solvent pump, and the solvent in the high-level tank dissolves and absorbs the sublimation material through the shell side of the second cooler and then returns to the low-level tank until the dissolution and absorption of the sublimation material in the second cooler is completed; (4) Repeat steps (2) and (3) until the distillation of the high freezing point system is completed.

7. The processing method according to claim 6, characterized in that: The outlet temperature of the condensate in the first-stage condenser is the same as the operating temperature of the top of the distillation tower, and the outlet temperature of the condensate in the second-stage condenser is 20-50°C higher than the freezing point temperature of the higher freezing point component.

8. The processing method according to claim 6, characterized in that: After the dissolution and absorption of the desublimated material in the first cooler or the second cooler is completed, the first cooler or the second cooler is evacuated to make the pressure in the first cooler or the second cooler reach its working pressure.

9. The processing method according to claim 6, characterized in that: The solvent in the low-level tank is an inert solvent.

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