Device for removing dimethyl ether from C4 hydrocarbon

Abstract

The utility model belongs to the technical field of chemical engineering, and relates to a device for removing dimethyl ether from C4 hydrocarbon. The dimethyl ether removal device comprises a dimethyl ether removal tower, a condenser, a reflux oil-water separation tank, a C4 feeding pipeline, an extraction water feeding pipeline and a dimethyl ether aqueous solution pipeline, an outlet of the C4 feeding pipeline is connected with the dimethyl ether removal tower, a top outlet of the dimethyl ether removal tower is connected with the condenser through a pipeline, the condenser is connected with the reflux oil-water separation tank through a pipeline, and the reflux oil-water separation tank is connected with the dimethyl ether aqueous solution pipeline through a pipeline. An oil phase outlet of the reflux oil-water separation tank is connected with the dimethyl ether removal tower through a pipeline, the extraction water feeding pipeline is connected with an inlet of the reflux oil-water separation tank, and a water phase outlet of the reflux oil-water separation tank is connected with a dimethyl ether water solution pipeline. According to the utility model, dimethyl ether in C4 hydrocarbon can be efficiently separated, namely more C4 hydrocarbon is refluxed under similar operation, and more dimethyl ether is discharged.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry and relates to a device for removing dimethyl ether from C4 hydrocarbons. Background Art

[0002] C4 hydrocarbons mainly come from byproducts of atmospheric and vacuum decompression, catalytic cracking and steam cracking units, including C4 alkanes isobutane and n-butane, C4 olefins isobutylene, butadiene, 1-butene, cis-2-butene, trans-2-butene, a small amount of C3 light components and C5 heavy components, as well as a small amount of oxides such as methanol, water, and dimethyl ether carried during the production process. In recent years, with the development of coal chemical industry, MTP and MTO units have also produced a certain amount of C4 fractions as byproducts.

[0003] C4 hydrocarbons have gradually changed from gas fuels in the traditional sense to chemical raw materials, which are used to produce alkylated gasoline, sec-butyl acetate, butanone and other products. Among them, the synthesis of methyl tert-butyl ether by the reaction of isobutylene and methanol is currently the main way to utilize C4 in China. In order to produce more methyl tert-butyl ether, linear butene is usually isomerized into isobutylene. The isomerization catalyst has strict requirements on the content of oxides. Patent CN203558988U removes dimethyl ether and methanol from C4 by combining a de-dimethyl ether tower and a water scrubber.

[0004] Dimethyl ether has a swelling property on some rubbers. If C4 is used as civilian liquefied petroleum gas, in order to reduce the risk of swelling and leakage of the gas cylinder sealing ring, the dimethyl ether content in C4 also needs to be controlled or removed.

[0005] C4 components and dimethyl ether can form a variety of azeotropes, which are difficult to separate by distillation operation and easily lead to entrainment and loss of C4 components. In order to improve the utilization value of C4 hydrocarbons, an efficient C4 hydrocarbon demethylation device is needed. Utility Model Content

[0006] The purpose of the utility model is to provide a device for removing dimethyl ether from C4 hydrocarbons in view of the above problems.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A device for removing dimethyl ether from C4 hydrocarbons comprises a de-dimethyl ether tower, a condenser, a reflux oil-water separation tank, a C4 feed pipeline, an extraction water feed pipeline, and a dimethyl ether aqueous solution pipeline, wherein the outlet of the C4 feed pipeline is connected to the de-dimethyl ether tower, the top outlet of the de-dimethyl ether tower is connected to the condenser through a pipeline, the condenser is connected to the reflux oil-water separation tank through a pipeline, the oil phase outlet of the reflux oil-water separation tank is connected to the de-dimethyl ether tower through a pipeline, the extraction water feed pipeline is connected to the inlet of the reflux oil-water separation tank, and the water phase outlet of the reflux oil-water separation tank is connected to the dimethyl ether aqueous solution pipeline.

[0009] The above-mentioned device for removing dimethyl ether from C4 hydrocarbons also includes a feed oil-water separation tank, a C4 pre-feed pipeline, and an extraction water pre-feed pipeline. The C4 pre-feed pipeline and the extraction water pre-feed pipeline are connected to the inlet of the feed oil-water separation tank, the C4 feed pipeline is connected to the oil phase outlet of the feed oil-water separation tank, and the two ends of the extraction water feed pipeline are respectively connected to the water phase outlet of the feed oil-water separation tank and the inlet of the reflux oil-water separation tank.

[0010] In the above-mentioned device for removing dimethyl ether from carbon four hydrocarbons, the dimethyl ether removal tower is provided with a reboiler, which is connected to the bottom of the dimethyl ether removal tower; a reflux pump is provided on the pipeline connecting the oil phase outlet of the reflux oil-water separation tank and the dimethyl ether removal tower.

[0011] In the above-mentioned device for removing dimethyl ether from C4 hydrocarbons, a preheater is provided on the C4 feed pipeline, and the heat source inlet of the preheater is connected to the bottom liquid phase outlet of the dimethyl ether removal tower.

[0012] The above-mentioned device for removing dimethyl ether from carbon four hydrocarbons also includes a bottom pump, the inlet of which is connected to the bottom of the dimethyl ether removal tower, and the outlet of which is connected to the heat source inlet of the preheater.

[0013] In the above-mentioned device for removing dimethyl ether from C4 hydrocarbons, a coalescer is provided in the reflux oil-water separation tank and the feed oil-water separation tank.

[0014] Compared with the existing technology, the advantages of the utility model are:

[0015] 1. The utility model can efficiently separate dimethyl ether from C4 hydrocarbons, that is, more C4 hydrocarbons can be refluxed and more dimethyl ether can be discharged under similar operations.

[0016] 2. The C4 hydrocarbons carried in the removed dimethyl ether are greatly reduced, which reduces the loss of C4 hydrocarbons in the process of removing dimethyl ether.

[0017] 3. While removing dimethyl ether from C4 hydrocarbons, it can also separate methanol entrained in C4 hydrocarbons.

[0018] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural schematic diagram of the utility model.

[0020] Figure 2 It is another structural schematic diagram of the utility model.

[0021] Figure 3It is a schematic diagram of the reflux oil-water separation tank.

[0022] In the figure: dimethyl ether removal tower 1, condenser 2, reflux oil-water separation tank 3, reflux pump 4, reboiler 5, tower bottom pump 6, preheater 7, feed oil-water separation tank 8, C4 feed pipeline 10, C4 pre-feed pipeline 10A, extraction water feed pipeline 11, extraction water pre-feed pipeline 11A, dimethyl ether aqueous solution pipeline 12. DETAILED DESCRIPTION

[0023] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0024] Example 1

[0025] The utility model provides a device for removing dimethyl ether from C4 hydrocarbons, such as Figure 1 As shown, a device for removing dimethyl ether from C4 hydrocarbons comprises a de-dimethyl ether tower 1, a condenser 2, a reflux oil-water separation tank 3, a C4 feed pipeline 10, an extraction water feed pipeline 11, and a dimethyl ether aqueous solution pipeline 12, wherein the outlet of the C4 feed pipeline 10 is connected to the de-dimethyl ether tower 1, the top outlet of the de-dimethyl ether tower 1 is connected to the condenser 2 through a pipeline, the condenser 2 is connected to the reflux oil-water separation tank 3 through a pipeline, the oil phase outlet of the reflux oil-water separation tank 3 is connected to the de-dimethyl ether tower 1 through a pipeline, the extraction water feed pipeline 11 is connected to the inlet of the reflux oil-water separation tank 3, and the water phase outlet of the reflux oil-water separation tank 3 is connected to the dimethyl ether aqueous solution pipeline 12.

[0026] Furthermore, the demethyl ether tower 1 is provided with a reboiler 5, which is connected to the bottom of the demethyl ether tower 1; a reflux pump 4 is provided on the pipeline connecting the oil phase outlet of the reflux oil-water separation tank 3 and the demethyl ether tower 1.

[0027] A preheater 7 is provided on the C4 feed pipeline 10, and the heat source inlet of the preheater 7 is connected to the bottom liquid phase outlet of the de-dimethyl ether tower 1. Preferably, a tower bottom pump 6 is also included, the inlet of the tower bottom pump 6 is connected to the tower bottom of the de-dimethyl ether tower 1, and the outlet of the tower bottom pump 6 is connected to the heat source inlet of the preheater 7.

[0028] In order to improve the effect of oil-water separation, Figure 3 As shown, a coalescer 100 is provided in the reflux oil-water separation tank 3. The coalescer is a prior art and a commercial product can be used. The coalescer is generally designed and manufactured according to the principles of collision, swirl, coalescence, sedimentation, etc., which can reduce the mutual entrainment between oil and water in liquid-liquid separation and significantly promote the effect of liquid-liquid separation.

[0029] Specifically, C4 hydrocarbons containing dimethyl ether are fed into the de-dimethyl ether tower 1 through the C4 feed pipeline 10 for distillation, and the tower bottom obtains C4 hydrocarbons after de-dimethyl ether is removed, which are transported through the tower bottom pump 6 and heated in the preheater 7 before being sent out of the device. C4 hydrocarbons enriched in dimethyl ether are obtained at the top of the de-dimethyl ether tower 1, and after condensation, they are mixed with the introduced extraction water in the reflux oil-water separation tank 3 and separated into oil and water; the oil phase in the reflux oil-water separation tank 3 is hydrocarbons containing part of dimethyl ether, which is returned to the top of the de-dimethyl ether tower 1 as reflux; the water phase in the reflux oil-water separation tank 3 is extraction water containing part of dimethyl ether, which is sent out for the next step of treatment.

[0030] By separating dimethyl ether together with extraction water, the entrainment amount of C4 hydrocarbons in dimethyl ether can be reduced, the loss of C4 hydrocarbons can be reduced, and the difficulty of separating dimethyl ether from C4 hydrocarbons can be reduced.

[0031] Taking the treatment of a certain C4 hydrocarbon containing 0.2% dimethyl ether as an example, distillation is carried out in a de-dimethyl ether tower 1 equipped with 9 meters of high-efficiency fillers, the operating pressure of the de-dimethyl ether tower 1 is 1.0MPa, the top and bottom temperatures are 66°C and 80°C respectively, and the content of dimethyl ether in the C4 hydrocarbon obtained in the bottom is less than 20ppm; the amount of extraction water added to the reflux oil-water separation tank 3 is 50% of the C4 feed amount, the ratio of the content of C4 hydrocarbon to dimethyl ether in the oil phase of the reflux oil-water separation tank 3 is 129, and the ratio of the content of C4 hydrocarbon to dimethyl ether in the water phase is 1.5. That is, the hydrocarbon ether ratio of 129 in the top reflux is much higher than the hydrocarbon ether ratio of 1.5 in the top delivery material, and the separation of C4 hydrocarbon and dimethyl ether can be effectively completed by combining with the de-dimethyl ether tower.

[0032] Comparative Example 1

[0033] For comparison, with the apparatus shown in patent CN218089443U, referring to the method of Example 1, the hydrocarbon ether ratio in the top reflux and the hydrocarbon ether ratio in the top delivery material are the same, both 11.5. Compared with Example 1, the C4 hydrocarbons entrained by the same dimethyl ether removed from the top of the tower are 11.5 / 1.5=7.7 times that of Example 1.

[0034] Example 2

[0035] The structure and working principle of this embodiment are basically the same as those of Embodiment 1, except that Figure 2The device for removing dimethyl ether from C4 hydrocarbons shown in the figure also includes a feed oil-water separation tank 8, a C4 pre-feed pipeline 10A, and an extraction water pre-feed pipeline 11A. The C4 pre-feed pipeline 10A and the extraction water pre-feed pipeline 11A are connected to the inlet of the feed oil-water separation tank 8, the C4 feed pipeline 10 is connected to the oil phase outlet of the feed oil-water separation tank 8, and the two ends of the extraction water feed pipeline 11 are respectively connected to the water phase outlet of the feed oil-water separation tank 8 and the inlet of the reflux oil-water separation tank 3. Preferably, a coalescer is also provided in the feed oil-water separation tank 8, and its structure is the same as that of the reflux oil-water separation tank 3.

[0036] As mentioned above, C4 hydrocarbons have a wide range of sources. In some cases, the content of dimethyl ether and methanol in C4 hydrocarbons can be very high. For example, a certain type of C4 hydrocarbon produced as a by-product of coal chemical industry contains 5.3% methanol and 3.9% dimethyl ether respectively.

[0037] C4 hydrocarbons with high oxide content are fed into the feed oil-water separation tank 8 through the C4 pre-feed pipeline 10A, and are separated from the oil and water by the extraction water fed through the extraction water pre-feed pipeline 11A. The methanol and dimethyl ether contents in the oil phase fed into the demethyl ether tower 1 through the C4 feed pipeline 10 are 0.3% and 3.0% respectively. The separated water phase from the feed oil-water separation tank 8 is fed to the reflux oil-water separation tank 3 through the extraction water feed pipeline 11 for continued use.

[0038] The top and bottom temperatures of the de-dimethyl ether tower 1 are 61°C and 80°C respectively, the dimethyl ether content in the C4 hydrocarbons obtained in the bottom of the tower is less than 10ppm, and the methanol content is less than 20ppm; the amount of extraction water added to the feed oil-water separation tank 8 is 70% of the C4 feed amount, the ratio of the C4 hydrocarbons to dimethyl ether in the oil phase of the reflux oil-water separation tank 3 is 5.6, and the ratio of the C4 hydrocarbons to dimethyl ether in the water phase is 0.1. That is, the hydrocarbon ether ratio of 5.6 in the top reflux is much higher than the hydrocarbon ether ratio of 0.1 in the top delivery material, and the separation of C4 hydrocarbons and dimethyl ether can be effectively completed by combining with the de-dimethyl ether tower.

[0039] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways without departing from the spirit of the present invention.

Claims

1. A device for removing dimethyl ether from C4 hydrocarbons, comprising a dimethyl ether removal tower (1), a condenser (2), a reflux oil-water separation tank (3), a C4 feed pipeline (10), an extraction water feed pipeline (11), and a dimethyl ether aqueous solution pipeline (12), characterized in that: The outlet of the C4 feed pipeline (10) is connected to the de-dimethyl ether tower (1), the top outlet of the de-dimethyl ether tower (1) is connected to the condenser (2) via a pipeline, the condenser (2) is connected to the reflux oil-water separation tank (3) via a pipeline, the oil phase outlet of the reflux oil-water separation tank (3) is connected to the de-dimethyl ether tower (1) via a pipeline, the extraction water feed pipeline (11) is connected to the inlet of the reflux oil-water separation tank (3), and the water phase outlet of the reflux oil-water separation tank (3) is connected to the dimethyl ether aqueous solution pipeline (12).

2. The device for removing dimethyl ether from C4 hydrocarbons according to claim 1, characterized in that: It also includes a feed oil-water separation tank (8), a C4 pre-feed pipeline (10A), and an extraction water pre-feed pipeline (11A); the C4 pre-feed pipeline (10A) and the extraction water pre-feed pipeline (11A) are connected to the inlet of the feed oil-water separation tank (8); the C4 feed pipeline (10) is connected to the oil phase outlet of the feed oil-water separation tank (8); and the two ends of the extraction water feed pipeline (11) are respectively connected to the water phase outlet of the feed oil-water separation tank (8) and the inlet of the reflux oil-water separation tank (3).

3. The device for removing dimethyl ether from C4 hydrocarbons according to claim 1 or 2, characterized in that: The de-dimethyl ether tower (1) is provided with a reboiler (5), and the reboiler (5) is connected to the tower kettle of the de-dimethyl ether tower (1); a reflux pump (4) is provided on the pipeline connecting the oil phase outlet of the reflux oil-water separation tank (3) and the de-dimethyl ether tower (1).

4. The device for removing dimethyl ether from C4 hydrocarbons according to claim 1 or 2, characterized in that: The C4 feed pipeline (10) is provided with a preheater (7), and the heat source inlet of the preheater (7) is connected to the bottom liquid phase outlet of the dedimethyl ether tower (1).

5. The device for removing dimethyl ether from C4 hydrocarbons according to claim 4, characterized in that: It also comprises a bottom pump (6), the inlet of the bottom pump (6) is connected to the bottom of the dimethyl ether removal tower (1), and the outlet of the bottom pump (6) is connected to the heat source inlet of the preheater (7).

6. The device for removing dimethyl ether from C4 hydrocarbons according to claim 1 or 2, characterized in that: The reflux oil-water separation tank (3) and the feed oil-water separation tank (8) are provided with coalescers.

Images