CN215975596U

CN215975596U - DMTO-IIC4 recycling and feeding system

Info

Publication number: CN215975596U
Application number: CN202120458346.1U
Authority: CN
Inventors: 刘恒; 孙振江; 阎伟华; 许云峰; 张伟
Original assignee: Pucheng Clean Energy Chemical Co Ltd
Current assignee: Pucheng Clean Energy Chemical Co Ltd
Priority date: 2021-03-03
Filing date: 2021-03-03
Publication date: 2022-03-08
Anticipated expiration: 2031-03-03

Abstract

The utility model relates to a DMTO-IIC4 recycling feeding system, which comprises a debenzolization tower, a C4 depropanization tower, a start-up debutanization tower and a C4 vaporizer: a debenzolization feeding pipeline of the debenzolization tower is communicated with a C4+ raw material pipeline, and a start-up debutanization feeding pipeline of the start-up debutanization tower is communicated with a C4+ raw material pipeline; the debenzolization tower is communicated with a C4 gas-phase feed line; the start-up debutanizer is communicated with a C4 liquid phase feed line of a C4 vaporizer through a C4 liquid phase feed line; the C4 depropanizing tower is communicated with an olefin separation hydrocarbon feeding pipeline, a liquid phase pipeline at the bottom of the C4 depropanizing tower is respectively communicated with a C4 vaporizer through a C4 liquid phase feeding pipeline, is communicated with a debenzolization feeding pipeline of the debenzolization tower through a C4 liquid phase supplementing pipeline, and is communicated with the debutanizing tower through a C4+ discharging pipeline; the C4 vaporizer was connected to a C4 liquid phase addition line from the C4 tank field; the accumulation of C4 reaction oil substances is solved, the C4 reaction can enter a stable state as soon as possible at the initial stage of starting, and the stability of C4 refining is ensured.

Description

DMTO-IIC4 recycling and feeding system

Technical Field

The utility model relates to the technical field of chemical industry, in particular to a DMTO-IIC4 recycling and feeding system.

Background

DMTO-II is a second generation technology for preparing olefin from methanol, is the only second generation production device put into use in China at present, wherein a C4 recycling unit is the key of the technology which is different from the first generation MTO technology. The raw materials in the feed system of the C4 recycling unit are from two parts, one part is that the gas phase mixture C4 at the top of the olefin separation and debenzolization tower is sent to a C4 feed gas phase pipeline, and the other part is from the liquid phase at the bottom of the C4 depropanization tower, and is conveyed to a C4 vaporizer by the tower pressure to be gasified and then is merged into a C4 feed gas phase pipeline. The mixed gas phase C4 was fed as C4 recycle unit.

C4 reaction is unstable at the initial start-up stage, and no conveyable material is available for the C4 reaction in the C4 depropanizer for a long time, so that the C4 reaction cannot effectively control the feed flow; when MTO is under low load, the novel catalyst causes the shortage of C4 raw material, and after the MTO load is as low as 200t/h, C4 is unstable in reaction and easy to deeply crack due to the shortage of the raw material; when the device is operated for a long period, oil carried in C4 reaction gas enters a C4 quenching water washing tower and is washed by water, so that the oil content in water washing water seriously exceeds the standard, a sewage stripping tower cannot treat the oil which exceeds the standard, the sewage index seriously exceeds the standard, and a sewage system is crashed.

The C4 reaction produces a small amount of C6+ (n-methylbenzene) and light oil, the initial light oil chain is short and light and cannot be directly washed by water, meanwhile, a small amount of short-chain light oil (including long-chain alcohol) in the water washing water can be resolved into product gas, gas phase components mixed with C6+ light oil enter a C4 compression separation unit, and in a C4 depropanizer, C6+ and light oil remain at the bottom of the tower. The original process directly feeds the C4 vaporizer from the bottom of the C4 depropanizer, and the part of C6+ and light oil are sent to the C4 reactor again to participate in the reaction, so that the reaction chain is further lengthened, and the reaction chain stays in a water system during water washing. Over time, longer chains are produced more and more, and more oil components are produced, exceeding the oil balance of the water system. Causing the sewage discharge to exceed the standard.

If the reaction is carried out smoothly in the original feeding system design, the C4 depropanizer material can be accumulated gradually along with the time, and the condition of circular supply is achieved. However, in the actual process of starting up, the reaction feeding amount of the C4 is too little in the initial stage, the reaction depth cannot be effectively controlled, a large amount of C4 is reacted into too light components, the material accumulation cannot be realized in the C4 depropanizer, the total feeding amount cannot be increased, the reaction depth of the C4 cannot be controlled, and the dead cycle is uncontrollable, so that the starting up is unstable.

The original design considers the early MTO catalyst, and in recent years, the MTO catalyst is updated, the yield of diene is continuously improved, and simultaneously, the C4+ component is reduced, so that the C4 raw material is not supplied enough under the same load condition.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects of the prior art, the utility model aims to provide a DMTO-IIC4 recycling feeding system which can separate C5+ components by rectification before feeding, solve the accumulation of oil substances of a C4 reaction, increase a material replenishing line of a tank area, temporarily replace materials in a C4 depropanizer kettle in the initial stage of starting, enable the C4 reaction to enter a stable state as soon as possible, and ensure the stability of C4 recycling by purchasing C4 raw materials from the outside and replenishing the raw materials to the system through the line when the C4 raw materials are insufficient and the low load cannot be maintained at the low load of MTO.

In order to achieve the purpose, the utility model adopts the following technical scheme that the DMTO-IIC4 recycling feeding system comprises a debenzolization tower, a C4 depropanization tower, a start-up debutanization tower and a C4 vaporizer:

a debenzolization feeding pipeline of the debenzolization tower is communicated with a C4+ raw material pipeline, and a start-up debulking feeding pipeline of the start-up debulking tower is communicated with a C4+ raw material pipeline;

the debenzolization tower is communicated with a C4 gas-phase feed line; the bottom of the debenzolization tower is communicated with a C5 product collecting tank through a C5 product collecting pipeline;

the start-up debutanizer is communicated with a C4 liquid phase feed line of a C4 vaporizer through a C4 liquid phase feed line; the top of the start-up debutanizer is communicated with a C5 collection line communicated with a C5 tank field;

the C4 depropanizing tower is communicated with an olefin separation hydrocarbon feeding pipeline, a liquid phase pipeline at the bottom of the C4 depropanizing tower is respectively communicated with a C4 vaporizer through a C4 liquid phase feeding pipeline, is communicated with a debenzolization feeding pipeline of the debenzolization tower through a C4 liquid phase supplementing pipeline, and is communicated with a debutanizer through a C4+ discharging pipeline;

the C4 vaporizer is communicated with a C4 liquid phase adding pipeline from a C4 tank area, and a C4 gas phase discharging pipeline arranged on the C4 vaporizer is communicated with a C4 gas phase feeding pipeline.

The top of the debenzolization tower is communicated with a debenzolization tower reflux tank through a gas-phase mixed discharge pipeline, and the top of the debenzolization tower reflux tank is communicated with a C4 gas-phase feed line;

a liquid phase mixed discharging pipeline arranged at the top of the start-up debutanizer is connected with a start-up debutanizer reflux tank, and the top of the start-up debutanizer reflux tank is communicated with a C4 liquid phase feeding pipeline;

the olefin discharging pipeline at the top of the C4 depropanizing tower is communicated with a C4 depropanizing tower reflux tank; the C4 depropanizer reflux drum is in communication with an olefin separation hydrocarbon feed line.

The debenzolization tower reflux tank is communicated with the debenzolization tower through a C4 liquid phase reflux pipeline, and the C4 liquid phase reflux pipeline is connected with a first reflux pump.

The C4 depropanizing tower reflux tank is communicated with the C4 depropanizing tower through a liquid phase reflux pipeline, and a second reflux pump is arranged on the liquid phase reflux pipeline.

The start-up debuding tower reflux tank is communicated with the start-up debuding tower through a liquid phase reflux pipeline, and a third reflux pump is arranged on the liquid phase reflux pipeline and communicated with the liquid phase reflux pipeline.

And a pressurizing pump is arranged on the C4 liquid phase feed line.

The C4 liquid phase feed line is connected with a C4 collection line communicated with the C4 product tank, and the C4 collection line is positioned at the downstream of the booster pump.

The utility model has the beneficial effects that: 1. the C5+ material is rectified and separated by the rectifying tower, so that the material entering the C4 reaction does not contain C6+ light oil, the content of oil in the water washing water can be effectively reduced, and the problem that the oil in a water system exceeds the standard is solved.

2. The start-up debutanizer is used as C4 main liquid raw material for feeding through modifying a discharge branch line at the top of the start-up debutanizer, and the debenzolization tower is used as a load balancing measure, so that a separated heavy component rectifying system can operate more flexibly.

3. By introducing mixed C4 from a C4 tank area as liquid-phase feed of a C4 vaporizer, the unstable deep reaction caused by insufficient C4 feed can be compensated at the initial stage of C4 start-up, and the C4 start-up process enters a stable state as soon as possible. During normal operation, when the load of an MTO system is too low and the C4 is not sufficiently fed, the C4 can be purchased and mixed externally, raw materials are supplemented to the system through the flow, and the stability and the yield increase of the C4 reaction are ensured.

Drawings

FIG. 1 is a schematic view of the piping connection of the present invention;

Detailed Description

The utility model is described in detail below with reference to the figures and examples.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the present invention, "a plurality" means two or more unless otherwise specified.

The DMTO-IIC4 recycling feeding system as shown in FIG. 1, a debenzolization feeding pipeline 7 is arranged at one side of a debenzolization tower 1, a C5 product collecting pipeline 12 is arranged at the bottom of the debenzolization tower 1, the C5 product collecting pipeline 12 is communicated with a C5 product tank area, a gas-phase mixed discharging pipeline 9 is communicated with the top of the debenzolization tower 1, a first heater 26 is arranged on the gas-phase mixed discharging pipeline 9, the gas-phase mixed discharging pipeline 9 is communicated with a debenzolization tower reflux tank 10, the reflux tank 10 is communicated with a C4 gas-phase feeding pipeline 11, the reflux tank 10 is communicated with the debenzolization tower 1 through a liquid-phase reflux pipeline 30, and a first reflux pump 25 is arranged on the liquid-phase reflux pipeline 30;

the top of the C4 depropanizing tower 2 is communicated with a C4 depropanizing tower reflux tank 24 through an olefin discharging pipeline 13, the C4 depropanizing tower reflux tank 24 is communicated with a light hydrocarbon feeding pipeline 27, the C4 depropanizing tower reflux tank 24 is communicated with the C4 depropanizing tower 2 through a reflux pipeline 32, and a second reflux pump 31 is arranged on the C4 reflux pipeline 32; a second heater 29 is arranged on the olefin discharging pipeline 13;

the bottom of the C4 depropanizing tower 2 is communicated with a C4 vaporizer 4 through a C4 liquid phase pipeline 15, the C4 liquid phase pipeline 15 is connected with a C4 discharge pipeline 14, and a C4 gas phase discharge pipeline 17 arranged on the C4 vaporizer 4 is communicated with a C4 gas phase feed line 11;

the top of the start-up debutanizer 3 is provided with a top liquid phase mixed discharging pipeline 18 of the start-up debutanizer and a reflux tank 19 of the start-up debutanizer, and the liquid phase mixed discharging pipeline 18 is provided with a third heater 28; a C4 liquid phase feed line 23 communicated with the start-up debutanizer reflux tank 19 is communicated with a C4 collecting line 22 communicated with a C4 product tank, and the C4 collecting line 22 is positioned at the downstream of the booster pump 21; the start-up debutanizer reflux tank 19 is communicated with the start-up debutanizer 3 through a start-up debutanizer reflux pipeline 33, and a third reflux pump 20 is arranged on the start-up debutanizer reflux pipeline 33 and communicated with the start-up debutanizer reflux pipeline 33;

the C4+ raw material pipeline 5 led out from the bottom of the low-pressure depropanizing tower is respectively communicated with the start-up debutanizing tower feeding pipeline 7 and the debenzolization feeding pipeline 6, and the C4+ raw material led out from the bottom of the low-pressure depropanizing tower respectively enters the debenzolization tower 1 and the start-up debutanizing tower 3 through the debenzolization feeding pipeline 7 and the debenzolization feeding pipeline 6 to serve as the raw materials of the debenzolization tower 1 and the start-up debutanizing tower 3.

A three-way side port is arranged on a C4 liquid phase pipeline 15 at the bottom of the C4 depropanizing tower 2, the three-way side port is communicated with an inlet of the debenzolizing tower 1 through a C4 liquid phase supplementing pipeline 8, meanwhile, a manual valve is additionally arranged, and a C4 liquid phase at the bottom of the C4 depropanizing tower is used as the feeding material of the debenzolizing tower; when the system runs, a feed pipeline from a C4 depropanizer to a C4 vaporizer is cut off, the depropanizer is changed to a debenzolization tower, the components are rectified and separated by the debenzolization tower, C6+ and light oil components mixed in C4 feed are removed from the tower bottom of the debenzolization tower, and qualified mixed C4 components at the tower top enter a C4 gas-phase feed line in a gas-phase state;

the C4 liquid phase feed pipeline communicated with the top of the start-up debulking tower 3 is communicated with the C4 vaporizer 4, a tee joint is arranged on the C4 liquid phase feed pipeline 23, the C4 collecting pipeline 22 is connected with the tee joint, and the start-up debulking tower provides liquid phase C4 materials for the C4 vaporizer during operation. The raw olefin separation low-pressure depropanizer only conveys materials to the debenzolization tower when the C4 recycle is started, the raw olefin separation low-pressure depropanizer is modified to mainly feed materials to the start-up debutanization tower and simultaneously feed materials to the debenzolization tower, and the material amount entering the debenzolization tower is balanced according to the load condition of the start-up debutanization tower.

A tee joint is arranged at the end part of the C4 liquid phase pipeline 15 close to the C4 vaporizer 4, and the tee joint and the C4 tank area pass through a C4 liquid phase adding pipeline 16; at the initial start-up, the C4 vaporizer was replenished with C4 feedstock as required for the amount of C4 vaporized. Meanwhile, when MTO is in low-load operation, the start-up debutanizer is in short supply, and the C4 refining is unstable, C4 raw materials are purchased from the outside of a tank area, and the raw materials are also fed into the system through the pipeline.

At the initial start-up, the C4 vaporizer was replenished with C4 feedstock as required for the amount of C4 vaporized. The C4 enters a reaction stable state 10 hours earlier when the vehicle is started, and the time for discharging light components during the vehicle is shortened.

When the MTO is operated at low load, the start-up debutanizer is in short supply, and the C4 refining is unstable, C4 raw materials are purchased from the outside of a tank field and are also fed into the system through the pipeline. The optimal efficiency operation of the C4 recycling is ensured.

In operation, the liquid phase C4 material is provided to the C4 vaporizer by a start-up debutanizer circuit. Cutting off a feed pipeline from a C4 depropanizing tower to a C4 vaporizer, changing the feed pipeline into a debenzolization tower, rectifying and separating components by the debenzolization tower, removing C6+ and light oil components mixed in C4 feed at the tower bottom of the debenzolization tower, and enabling qualified mixed C4 components at the tower top to enter a C4 gas-phase feed line in a gas phase state.

The raw olefin separation low-pressure depropanizer only conveys materials to the debenzolization tower when the C4 recycle is started, the raw olefin separation low-pressure depropanizer is modified to mainly feed to the start-up debutanizer and simultaneously feed to the debenzolization tower, and the material amount entering the debenzolization tower is manually balanced according to the load condition of the start-up debutanizer.

Specifically, during operation, the mixed C4+ raw material at the bottom of the C4 depropanizing tower 2 does not directly enter the C4 vaporizer 4, but enters the debenzolization tower 1 through a modified pipeline, oil substances above C6+ are removed through rectification in the debenzolization tower 1, and a C4C5 gas-phase mixture is arranged at the top of the debenzolization tower 1 and is used as C4 gas-phase feed; the liquid phase at the top of the start-up debutanizer 3 is also a C4C5 liquid phase mixture without oily substances and is used as a C4 liquid phase feed; the C4 liquid phase from the tank farm is also an oil-free high quality C4 feedstock; the combination thoroughly solves the problem of accumulation of oil substances in the system after C4 reaction; the C4 raw material from the tank field can ensure that the C4 reaction can enter a stable state as soon as possible in the initial start-up period, and the C4 recycling stability can be ensured by supplementing the raw material at the low load.

The above embodiments are merely illustrative of the present invention, and should not be construed as limiting the scope of the present invention, and all designs identical or similar to the present invention are within the scope of the present invention.

Claims

1. A DMTO-IIC4 recycling feed system comprises a debenzolization tower (1), a C4 depropanization tower (2), a start-up debutanization tower (3) and a C4 vaporizer (4), and is characterized in that: a debenzolization feeding pipeline (6) of the debenzolization tower (1) is communicated with a C4+ raw material pipeline (5), and a start-up debulking feeding pipeline (7) of the start-up debulking tower (3) is communicated with a C4+ raw material pipeline (5); the debenzolization tower (1) is communicated with a C4 gas-phase feed line (11); the bottom of the debenzolization tower (1) is communicated with a C5 product collecting tank through a C5 product collecting pipeline (12); the start-up debutanizer (3) is communicated with a C4 liquid phase feed line (15) of a C4 vaporizer (4) through a C4 liquid phase feed line (23); the top of the start-up debutanizer (3) is communicated with a C5 collecting pipeline (28) communicated with a C5 tank field; the C4 depropanizing tower (2) is communicated with an olefin separation hydrocarbon feeding pipeline (27), a liquid phase pipeline at the bottom of the C4 depropanizing tower (2) is respectively communicated with a C4 vaporizer (4) through a C4 liquid phase feeding pipeline (15), a debenzolization feeding pipeline (6) of the debenzolization tower (1) through a C4 liquid phase supplementing pipeline (8), and a debutanizing tower through a C4+ discharging pipeline (14); the C4 vaporizer (4) is communicated with a C4 liquid phase adding pipeline (16) from a C4 tank area, and a C4 gas phase discharging pipeline (17) arranged on the C4 vaporizer (4) is communicated with a C4 gas phase feeding pipeline (11).

2. The DMTO-IIC4 remill feed system according to claim 1, wherein the top of the debenzolization tower (1) is communicated with a debenzolization tower reflux drum (10) through a gas phase mixing discharge line (9), and the top of the debenzolization tower reflux drum (10) is communicated with a C4 gas phase feed line (11); a liquid phase mixed discharging pipeline (18) arranged at the top of the start-up debutanizer (3) is connected with a start-up debutanizer reflux tank (19), and the top of the start-up debutanizer reflux tank (19) is communicated with a C4 liquid phase feeding pipeline (23); an olefin discharge pipeline (13) at the top of the C4 depropanizing tower (2) is communicated with a C4 depropanizing tower reflux tank (24); the C4 depropanizer reflux drum (24) is in communication with an olefin separation hydrocarbon feed line (27).

3. The DMTO-IIC4 recycle feed system of claim 2, wherein the debenzolization column reflux drum (10) is in communication with the debenzolization column (1) via a C4 liquid phase reflux line (30), the C4 liquid phase reflux line (30) having a first reflux pump (25) connected thereto.

4. The DMTO-IIC4 recycle feed system of claim 2, wherein the C4 depropanizer reflux drum (24) is in communication with the C4 depropanizer (2) via a liquid phase reflux line (32), the liquid phase reflux line (32) having a second reflux pump (31) disposed thereon.

5. The DMTO-IIC4 recycle feed system of claim 2, wherein the start-up debutanizer reflux drum (19) is in communication with the start-up debutanizer (3) via a liquid phase reflux line (32), and the liquid phase reflux line (32) is provided with a third reflux pump (20) in communication therewith.

6. The DMTO-IIC4 remill feed system according to claim 2, wherein a booster pump (21) is provided on the C4 liquid phase feed line (23).

7. The DMTO-IIC4 remill feeding system according to claim 6, wherein the C4 liquid phase feed line (23) is connected to a C4 collecting line (22) connected to the C4 product tank, and the C4 collecting line (22) is located downstream of the booster pump (21).