Online switchable product gas drying device for preparing propylene through propane dehydrogenation

Abstract

The utility model provides an online switchable product gas drying device for preparing propylene through propane dehydrogenation. The online switchable product gas drying device comprises two first dryers, a second dryer, a purging pipeline, a recovery pipeline and a regeneration pipeline, the two first dryers are arranged in parallel, first material inlets are formed in the upper parts of the first dryers, first material outlets are formed in the bottoms of the first dryers, the first material inlets of the two first dryers are connected through a pipeline, and the first material outlets of the two first dryers are connected through a pipeline; a second material inlet is formed in the upper portion of the second dryer, a second material outlet is formed in the bottom of the second dryer, and the second material inlet of the second dryer is connected with the first material inlets of the two first dryers through pipelines. And the second material outlet of the second dryer is connected with the first material outlets of the two first dryers through pipelines respectively. According to the utility model, the adsorbent can be replaced on line without stopping the device, and the economic loss caused by non-planned stopping is reduced.

Description

Technical Field

[0001] This utility model relates to a drying device, specifically an online-switchable product gas drying device for propane dehydrogenation to propylene production, belonging to the technical field of propane dehydrogenation to propylene production equipment. Background Technology

[0002] Propylene is an important chemical raw material, serving as an intermediate in the production of high-value-added products such as acrylic acid, propylene oxide, acrylonitrile, and polypropylene, with its consumption second only to ethylene. There are several processes for producing propylene, among which five are commonly used: fluidized bed catalytic cracking, olefin disproportionation, olefin cracking, methanol-to-olefins (MTO), and propane dehydrogenation (PDH). With the rapid growth in demand for downstream propylene derivatives, traditional processes using ethylene co-production and light oil (naphtha, light diesel) cracking can no longer meet market demand. The PDH process, with its advantages of low cost, high yield, and high economic efficiency, has become the main propylene production process. Among the currently industrialized propane dehydrogenation to propylene processes, UOP's Oleflex process is the most widely used.

[0003] In the Oleflex process's propane dehydrogenation to propylene unit, hydrogen is used for reduction after catalyst regeneration. Water is produced during this reduction process, and this water, mixed with the process gas, can freeze and clog the cooling exchange equipment in the downstream cryogenic separation unit. Simultaneously, DMDS (dimethyl disulfide) is injected into the reactor during operation to protect it and reduce coking. Under the high temperature of the reactor, DMDS reacts and decomposes with hydrogen hydrocarbons to generate hydrogen sulfide gas. To ensure the smooth operation of the downstream process, a drying unit capable of simultaneously adsorbing water and hydrogen sulfide is installed, and this drying unit is regenerable. Traditional drying units consist of two adsorption tanks. During normal operation, one adsorbs while the other regenerates and removes the adsorbed water and hydrogen sulfide. Although the adsorbent is regenerable, it still has a lifespan; once its lifespan is exhausted, it loses its adsorption capacity and needs to be replaced. With two adsorption tanks, online adsorbent replacement requires a complete unit shutdown. Unnecessary shutdowns can lead to significant economic losses. Utility Model Content

[0004] Based on the above background, the purpose of this utility model is to provide an online-switching product gas drying device for propane dehydrogenation to propylene, which enables the device to replace the adsorbent online without stopping the machine, thereby reducing the economic losses caused by unplanned shutdowns.

[0005] To achieve the above-mentioned objectives, this utility model provides the following technical solution:

[0006] An online-switchable product gas drying device for propane dehydrogenation to propylene includes two first dryers, one second dryer, a purge line, a recovery line, and a regeneration line. The two first dryers are connected in parallel. Each first dryer has a first material inlet at its upper part and a first material outlet at its bottom. The first material inlets and outlets of the two first dryers are connected by pipelines. The second dryer has a second material inlet at its upper part and a second material outlet at its bottom. The second material inlet of the second dryer is connected to the first material inlets of both first dryers by pipelines, and the second material outlet of the second dryer is connected to the first material outlets of both first dryers by pipelines. The system is connected by pipelines; one end of the purging pipeline is used to introduce external regeneration gas, and the other end of the purging pipeline is connected to the pipeline connecting the first material inlet of the two first dryers. The purging pipeline is equipped with a first purging control valve, a second purging control valve, and a purging switching valve. The purging switching valve is located near the end of the purging pipeline used to introduce external regeneration gas. The recovery pipeline is connected to the pipeline connecting the first material outlet of the two first dryers. The recovery pipeline is equipped with a first recovery control valve, a second recovery control valve, and a third recovery control valve. One end of the regeneration pipeline is connected to the purging pipeline used to introduce external regeneration gas, and the other end of the regeneration pipeline is connected to the pipeline connecting the first material outlet of the two first dryers. The regeneration pipeline is equipped with a first regeneration control valve and a second regeneration control valve.

[0007] Preferably, the first purge control valve and the second purge control valve are connected in parallel and connected in series with the purge switching valve; the first recovery control valve and the second recovery control valve are connected in parallel and connected in series with the third recovery control valve; and the first regeneration control valve and the second regeneration control valve are connected in series.

[0008] Preferably, the pipeline connecting the second dryer to the first material inlet of the two first dryers is equipped with a first manual valve and a bypass valve, which are connected in parallel. The pipeline connecting the second dryer to the first material inlet of one of the first dryers is equipped with a second manual valve, and the pipeline connecting the second dryer to the first material inlet of the other first dryer is equipped with a third manual valve.

[0009] Preferably, a second hand valve is provided on the pipeline connecting the second dryer to the first material outlet of the two first dryers.

[0010] Preferably, the interiors of the two first dryers and the one second dryer are filled with a regenerable adsorbent for adsorbing water and hydrogen sulfide.

[0011] Preferably, the online switchable product gas drying device for propane dehydrogenation to propylene further includes an inlet pipeline and an outlet pipeline. The inlet pipeline is connected to the pipeline connecting the first material inlet of the two first dryers, and the outlet pipeline is connected to the pipeline connecting the first material outlet of the two first dryers.

[0012] As a preferred option, the outlet pipeline is equipped with an online moisture detector and an online hydrogen sulfide detector.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] This invention relates to an online-switchable product gas drying device for propane dehydrogenation to propylene. By setting up two first dryers, one second dryer, and related pipelines, the device can replace the adsorbent online without stopping, reducing economic losses caused by unplanned shutdowns. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of an online-switchable product gas drying device for propane dehydrogenation to propylene, according to this utility model. Detailed Implementation

[0017] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of this utility model is not limited to the following embodiments, and any modifications and / or alterations made to this utility model will fall within the protection scope of this utility model.

[0018] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following detailed description, many specific details are set forth to facilitate explanation and provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.

[0020] like Figure 1 As shown in the figure, an embodiment of the present invention discloses an online switchable product gas drying device for propane dehydrogenation to propylene, comprising two first dryers (first dryer A1 and first dryer B2, respectively), one second dryer 3, a purge line 4, a recovery line 5, and a regeneration line 6.

[0021] Two first dryers are connected in parallel. The first material inlet is located at the top of the first dryer and the first material outlet is located at the bottom of the first dryer. The first material inlets of the two first dryers are connected by pipelines, and the first material outlets of the two first dryers are connected by pipelines.

[0022] The second dryer has a second material inlet at the top and a second material outlet at the bottom. The second material inlet of the second dryer is connected to the first material inlets of the two first dryers through pipelines, and the second material outlet of the second dryer is connected to the first material outlet of the two first dryers through pipelines.

[0023] One end of the purge line is used to introduce external regeneration gas, and the other end is connected to the pipeline connecting the first material inlet of the two first dryers. The purge line is equipped with a first purge control valve 41, a second purge control valve 42, and a purge switching valve 43. The purge switching valve is located near the purge line end used to introduce external regeneration gas. The first and second purge control valves are connected in parallel and connected in series with the purge switching valve.

[0024] The recovery pipeline is connected to the pipeline connecting the first material outlet of the two first dryers. The recovery pipeline is equipped with a first recovery control valve 51, a second recovery control valve 53, and a third recovery control valve 52. The first and second recovery control valves are connected in parallel, and the third recovery control valve is connected in series.

[0025] One end of the regeneration pipeline is connected to one end of the purging pipeline used to introduce external regeneration gas, and the other end of the regeneration pipeline is connected to the pipeline connecting the first material outlet of the two first dryers. The regeneration pipeline is equipped with a first regeneration control valve 61 and a second regeneration control valve 62. The first regeneration control valve and the second regeneration control valve are connected in series.

[0026] The pipeline connecting the second dryer to the first material inlet of the two first dryers is equipped with a first hand valve 31 and a bypass valve 32, which are connected in parallel. The pipeline connecting the second dryer to the first material inlet of one of the first dryers is equipped with a second hand valve 34, and the pipeline connecting the second dryer to the first material inlet of the other first dryer is equipped with a third hand valve 35.

[0027] A second hand valve 33 is installed on the pipeline connecting the second dryer to the first material outlet of the two first dryers.

[0028] The two first dryers and one second dryer are all filled with regenerable adsorbent for adsorbing water and hydrogen sulfide. The second dryer is filled with nitrogen gas when in standby mode. The gas used for gas replacement in the second dryer is the product process gas, until the total oxygen and nitrogen content is less than 2%, and the replaced gas is discharged into the external wet flare system. The first dryer uses dry gas as the regenerator.

[0029] The online switchable product gas dryer for propane dehydrogenation to propylene also includes an inlet pipeline and an outlet pipeline. The inlet pipeline is connected to the pipeline connecting the first material inlet of the two first dryers, and the outlet pipeline is connected to the pipeline connecting the first material outlet of the two first dryers.

[0030] The outlet pipeline is equipped with an online moisture detector 8 and an online hydrogen sulfide detector 9.

[0031] The online switchable product gas drying unit for propane dehydrogenation to propylene also includes a programmable controller, which comprises an electrically connected computer display unit and a computer control unit, and the computer control unit is electrically connected to each of the aforementioned control valves.

[0032] The working principle of the online switchable product gas drying device for propane dehydrogenation to propylene is described in detail below. To distinguish the two first dryers, they are named First Dryer A and First Dryer B respectively.

[0033] The upstream product gas enters the first dryer A1 through control valves 11 and 12 on the inlet pipeline. After adsorption, it exits from the bottom through control valves 16 and 17 on the outlet pipeline and goes downstream. At the same time, the first dryer B2 is in the regeneration process. At this time, except for the control valves 21 and 22 at the inlet of the first dryer B2, the control valves 26 and 27 at the outlet, and the purge switching valve 43 on the purge pipeline 4, which are in the open state, all other related valves are in the closed state.

[0034] The specific regeneration steps are as follows:

[0035] The control valves 21 and 22 at the inlet of the first dryer B2 and the control valves 26 and 27 at the outlet are closed for isolation; the control valves 28 and 29 on the recovery line 5 connected to the outlet are opened, the third recovery control valve 52 on the recovery line 5 is opened, the first recovery control valve 51 is slowly opened to the downstream path to recover the internal product gas, the pressure is released to be equal to that of the downstream path, and the first recovery control valve 51 is closed.

[0036] The control valves 24 and 25 of the inlet pipeline connected to the purge pipeline 4 are opened, the first recovery control valve 51 is opened, and the second purge control valve 42 of the purge pipeline 4 is slowly opened to allow regeneration gas to enter from the top of the first dryer B2 to purge the residual material in the tank for further recovery of product gas. After the purge is completed, the first recovery control valve 51 and the third recovery control valve 52 on the recovery pipeline 5 are closed, and the first purge control valve 41 on the purge pipeline 4 is opened and the second purge control valve 42 is closed.

[0037] The first regeneration control valve 61 and the second regeneration control valve 62 on the regeneration pipeline 6 are opened, and the purge switching valve 43 on the purge pipeline 4 is slowly closed. The heated regeneration gas enters the reverse contact adsorbent from the bottom of the first dryer B2 through the regeneration pipeline 6 and the recovery pipeline 5 to remove moisture and hydrogen sulfide. After exiting from the top of the first dryer B2, it goes to the downstream cooling absorption device through the purge pipeline 4.

[0038] Heating stops when the temperature of the purge gas at the top of the first dryer B2 is close to that at the bottom. The regeneration gas at normal temperature continues to cool the adsorbent in the first dryer B2 through the same process. Cooling ends when the temperature of the purge gas at the top of the first dryer B2 is close to the normal temperature at the bottom again.

[0039] The purge switching valve 43 on the purge line 4 opens slowly, the first regeneration control valve 61 and the second regeneration control valve 62 on the regeneration line 6 close, the first purge control valve 41 on the purge line 4 closes, and the control valves 24 and 25 on the inlet line connected to the purge line 4 close.

[0040] The control valve 21 at the inlet of the first dryer B2 is opened, and the bypass valve 23 of the control valve 22 is slowly opened to introduce the product process gas for pressurization. The pressurization is equal to the pressure of the operating first dryer A1. Then the control valve 22 is opened and the bypass valve 23 is closed.

[0041] The third recovery control valve 52 on the recovery pipeline 5 is opened and the second recovery control valve 53 is opened slowly, continuously using the product process gas to thoroughly replace the components of the first dryer B2, so that its internal components are the same as during operation.

[0042] The program control valves 53 and 52 on the recovery pipeline 5 are closed, and the control valves 28 and 29 on the outlet pipeline connected to the recovery pipeline 5 are closed; the outlet control valves 26 and 27 are opened, and after the first dryer A1 and the first dryer B2 have been running in parallel for a period of time, the other first dryer is regenerated again.

[0043] When the adsorbent in the first dryer B2 reaches the end of its service life, the second dryer 3 needs to be switched online. The steps are as follows:

[0044] When the program is in the depressurization and recovery step, stop the program, open the third hand valve 35 of the pipeline connecting the first dryer A1 and the second dryer 3, and open the bypass valve 32 of the first hand valve 31 at the inlet of the second dryer 3.

[0045] The process gas is introduced into the second dryer 3 for replacement until the oxygen + nitrogen content is <2%. The replaced gas is discharged into the wet flare system. The first manual valve 31 at the inlet of the second dryer 3 is opened and the bypass valve 32 is closed.

[0046] Close the inlet and outlet manual valves of the first dryer B2 (to be replaced), close the third manual valve 35 of the pipeline connecting the first dryer A1 and the second dryer 3, open the second manual valve 34 of the pipeline connecting the first dryer B2 and the second dryer 3, and open the third manual valve 33 at the outlet of the second dryer 3; this will connect the second dryer 3 in parallel with the first dryer A1. After running the program, the second dryer 3 will regenerate and adsorb, and the program will continue from the pressure relief and recovery step. At this time, the refrigerant replacement operation can be performed on the first dryer B2 (to be replaced).

[0047] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. An in-line switchable product gas drying device for propane dehydrogenation to propylene, characterized by: The online switching product gas drying device for propane dehydrogenation to propylene comprises two first dryers, a second dryer, a purge pipeline, a recovery pipeline and a regeneration pipeline; the two first dryers are connected in parallel, the upper part of the first dryer is provided with a first material inlet, the bottom of the first dryer is provided with a first material outlet, the first material inlets of the two first dryers are connected through a pipeline, and the first material outlets of the two first dryers are connected through a pipeline; the upper part of the second dryer is provided with a second material inlet, the bottom of the second dryer is provided with a second material outlet, the second material inlet of the second dryer is connected with the first material inlets of the two first dryers through a pipeline respectively, and the second material outlet of the second dryer is connected with the first material outlets of the two first dryers through a pipeline respectively; one end of the purge pipeline is used for introducing external regeneration gas, the other end of the purge pipeline is connected with the pipeline connecting the first material inlets of the two first dryers, the purge pipeline is provided with a first purge control valve, a second purge control valve and a purge switching valve, and the purge switching valve is arranged adjacent to one end of the purge pipeline used for introducing external regeneration gas; the recovery pipeline is connected with the pipeline connecting the first material outlets of the two first dryers, and the recovery pipeline is provided with a first recovery control valve, a second recovery control valve and a third recovery control valve; one end of the regeneration pipeline is connected with one end of the purge pipeline used for introducing external regeneration gas, the other end of the regeneration pipeline is connected with the pipeline connecting the first material outlets of the two first dryers, and the regeneration pipeline is provided with a first regeneration control valve and a second regeneration control valve.

2. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 1, characterized in that: The first purge control valve and the second purge control valve are connected in parallel and connected in series with the purge switching valve; the first recovery control valve and the second recovery control valve are connected in parallel and connected in series with the third recovery control valve; and the first regeneration control valve and the second regeneration control valve are connected in series.

3. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 1, characterized in that: The pipeline connecting the first material inlets of the two first dryers with the second dryer is provided with a first hand valve and a bypass valve, the first hand valve and the bypass valve are connected in parallel, the pipeline connecting the first material inlet of one first dryer with the second dryer is provided with a second hand valve, and the pipeline connecting the first material inlet of the other first dryer with the second dryer is provided with a third hand valve.

4. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 1, characterized in that: The pipeline connecting the first material outlets of the two first dryers with the second dryer is provided with a second hand valve.

5. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 1, characterized in that: The interiors of the two first dryers and the second dryer are all filled with renewable adsorbents for adsorbing water and hydrogen sulfide.

6. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 1, characterized in that: The online switching product gas drying device for propane dehydrogenation to propylene further comprises an inlet pipeline and an outlet pipeline, the inlet pipeline is connected with the pipeline connecting the first material inlets of the two first dryers, and the outlet pipeline is connected with the pipeline connecting the first material outlets of the two first dryers.

7. The on-line switchable product gas drying device for propane dehydrogenation to propylene according to claim 6, characterized in that: The outlet pipeline is provided with a water content online detector and a hydrogen sulfide online detector.

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