CN109990201B

CN109990201B - Catalyst and propylene on-line mixer anti-blocking method

Info

Publication number: CN109990201B
Application number: CN201910282524.7A
Authority: CN
Inventors: 张辉; 张祖平; 邵长青; 周雪云
Original assignee: Sinopec Sk Wuhan Petrochemical Co ltd
Current assignee: Sinopec Sk Wuhan Petrochemical Co ltd
Priority date: 2019-04-10
Filing date: 2019-04-10
Publication date: 2021-05-11
Anticipated expiration: 2039-04-10
Also published as: CN109990201A

Abstract

The invention discloses an anti-blocking method for a catalyst and propylene online mixer, which relates to the field of chemical production and comprises the following steps: and respectively closing the first valve and the second valve, slowly opening the third valve at the same time, directly introducing flushing propylene into a low-temperature propylene condenser on a hydrogenated propylene pipeline for heat exchange and cooling, and conveying the cooled propylene to the catalyst and propylene on-line mixer together, wherein the inlet capillary orifice of the catalyst and propylene on-line mixer is subjected to pipe diameter reduction treatment. According to the invention, the propylene entering the catalyst and propylene on-line mixer is changed into propylene without hydrogen, so that the chemical reaction speed of the catalyst in contact with propylene in the inlet capillary port can be reduced, the probability of blockage of the inlet capillary port is reduced, the initial activity of the catalyst is reduced during prepolymerization, the catalyst is prevented from cracking to generate a large amount of fine powder, the content of fine powder in the process water outlet is reduced, and the environmental pollution is avoided.

Description

Catalyst and propylene on-line mixer anti-blocking method

Technical Field

The invention relates to the field of chemical production, in particular to an anti-blocking method for a catalyst and propylene online mixer.

Background

In the design of the existing loop process polypropylene device, propylene which is cooled by a low-temperature propylene condenser and used for conveying a catalyst (a Ziegler-Natta catalyst system) is propylene after hydrogen is added, when the propylene with the hydrogen is used for conveying the catalyst, an online mixer (a catalyst and propylene online mixer) of the catalyst is easy to block, and then propylene with large hydrogenation amount is easy to crack a main catalyst in a prepolymerization process, so that the content of fine powder of a product is ultrahigh, the online mixer of the catalyst is further blocked, once the online mixer of the catalyst is blocked, the main catalyst and a cocatalyst are interrupted for at least 20 minutes, and the stability of the quality of the polypropylene product is seriously influenced.

Secondly, propylene with large hydrogenation amount easily causes the cracking of a main catalyst in the prepolymerization process, causes the ultrahigh content of fine powder of a product, blocks downstream equipment or causes environmental pollution, and increases the unit consumption of propylene of a device.

Disclosure of Invention

In order to overcome the defects of related products in the prior art, the invention provides an anti-blocking method for a catalyst and propylene online mixer, which solves the problem that the existing catalyst and propylene online mixer is easy to block.

The invention provides an anti-blocking method for a catalyst and propylene online mixer, which comprises the following steps: the method comprises the following steps that a first valve is arranged on a flushing propylene pipeline, a second valve and a low-temperature propylene condenser are sequentially arranged on a hydrogenated propylene pipeline, a conducting pipeline and a third valve are arranged between the flushing propylene pipeline and the hydrogenated propylene pipeline, wherein the inlet of the conducting pipeline is positioned in front of the first valve, and the outlet of the conducting pipeline is positioned behind the second valve; and respectively closing the first valve and the second valve, slowly opening the third valve at the same time, directly introducing flushing propylene into a low-temperature propylene condenser on a hydrogenated propylene pipeline for heat exchange and cooling, conveying a catalyst by utilizing the cooled propylene, and conveying the catalyst and the cooled propylene into an online catalyst and propylene mixer, wherein an input capillary opening of the online catalyst and propylene mixer for conveying is subjected to pipe diameter reduction treatment.

In certain embodiments of the invention, the reduced temperature of the purge propylene is 10 ℃ after the low temperature propylene condenser exchanges heat to cool the purge propylene.

In certain embodiments of the invention, the flow rate of the catalyst after the inlet capillary opening has been treated by tube diameter reduction is not less than 0.07 m/s and the flow rate of propylene is not less than 1 m/s.

Compared with the prior art, the invention has the following advantages:

according to the anti-blocking method for the catalyst and propylene online mixer, propylene entering the catalyst and propylene online mixer is changed into propylene without hydrogen, so that the chemical reaction speed of the catalyst in contact with propylene in an input capillary port can be reduced, the probability of blockage of the input capillary port is reduced, long-period stable operation of the device is guaranteed, the product quality of the device is improved, the initial activity of the catalyst is reduced during prepolymerization, the catalyst is prevented from being cracked to generate a large amount of fine powder, the content of the fine powder in the process water outlet of a 500 working section is reduced, and environmental pollution is avoided.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic flow diagram of the catalyst and propylene anti-clogging process in an on-line mixer according to the present invention;

FIG. 2 is a schematic diagram of the process of the catalyst and propylene on-line mixer of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and that the following is a description of preferred embodiments of the invention. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present disclosure is set forth in order to provide a more thorough understanding thereof.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

Referring to fig. 1 and 2, the method for preventing the catalyst from being blocked in the online mixer of propylene comprises the following steps:

s101: a first valve V1 is arranged on a flushing propylene pipeline, a second valve V2 and a low-temperature propylene condenser E201 are arranged on a hydrogenated propylene pipeline in sequence, a communicating pipeline is arranged between the flushing propylene pipeline and the hydrogenated propylene pipeline, and a third valve V3 is arranged, wherein the inlet of the communicating pipeline is positioned in front of the first valve V1, and the outlet of the communicating pipeline is positioned behind the second valve V2.

S102: the first valve V1 and the second valve V2 are respectively closed, the third valve V3 is slowly opened, flushing propylene is directly introduced into a low-temperature propylene condenser E201 on a hydrogenated propylene pipeline for heat exchange and cooling, the cooled propylene is used for conveying the catalyst, the catalyst and the cooled propylene are conveyed into an online catalyst and propylene mixer, and the input capillary orifice of the online catalyst and propylene mixer for conveying is subjected to pipe diameter reduction treatment.

After the first valve V1 was closed, the third valve V3 was slowly opened and finally the second valve V2 was closed, thereby adjusting the hydrogenated propylene to propylene without hydrogen.

Since the chain growth constant increases when hydrogen is present in the propylene entering the catalyst and propylene on-line mixer, the increase in the chain growth rate constant is related to the reactivation of the "dormant" centers by chain transfer, which are formed after the insertion of the first monomer into the Ti-H bond, can also be reactivated by hydrogen. Meanwhile, the contact time of the catalyst with a higher active center and propylene in an input capillary port of the online mixer of the catalyst and propylene is reduced as much as possible by reducing the pipe diameter and increasing the flow rate of the catalyst and the flow rate of the propylene, and the probability of blockage is reduced, for example, in a 7-ten-thousand-ton production device, the pipe diameter of the input capillary port is 1/8 inches, when the device is lifted to 20 ten thousand tons, the pipe diameter of the corresponding input capillary port is 1/4 inches, the flow rate of the catalyst is kept to be not less than 0.07 m/s, the flow rate of the propylene is not less than 1 m/s, and the contact time of the catalyst and the propylene in the input capillary port of the online mixer of the catalyst and the propylene is reduced without affecting normal production. In the embodiment of the invention, after the low-temperature propylene condenser E201 exchanges heat and cools the flushing propylene, the temperature of the reduced flushing propylene is 10 ℃, the catalyst is sent into the catalyst and propylene on-line mixer by using cold propylene without hydrogen, the chemical reaction speed of the catalyst in the inlet capillary port when contacting with the propylene is further reduced, and the probability of blockage of the inlet capillary port is reduced.

Those not described in detail in this specification are within the skill of the art. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing detailed description, or equivalent changes may be made in some of the features of the embodiments. All equivalents that can be substituted by the contents of the specification of the present invention and applied directly or indirectly to other related technical fields are within the scope of the present invention.

Claims

1. An anti-clogging method for an online mixer of a catalyst and propylene is characterized by comprising the following steps:

the method comprises the following steps that a first valve is arranged on a flushing propylene pipeline, a second valve and a low-temperature propylene condenser are sequentially arranged on a hydrogenated propylene pipeline, a conducting pipeline and a third valve are arranged between the flushing propylene pipeline and the hydrogenated propylene pipeline, wherein the inlet of the conducting pipeline is positioned in front of the first valve, and the outlet of the conducting pipeline is positioned behind the second valve;

and respectively closing the first valve and the second valve, slowly opening the third valve at the same time, directly introducing flushing propylene into a low-temperature propylene condenser on a hydrogenated propylene pipeline for heat exchange and cooling, conveying a catalyst by utilizing the cooled propylene, and conveying the catalyst and the cooled propylene into an online catalyst and propylene mixer, wherein an input capillary opening of the online catalyst and propylene mixer for conveying is subjected to pipe diameter reduction treatment.

2. The catalyst and propylene on-line mixer anti-clogging method of claim 1, wherein: after the low-temperature propylene condenser exchanges heat and cools the flushing propylene, the temperature of the flushing propylene is reduced to 10 ℃.

3. The catalyst and propylene on-line mixer anti-clogging method of claim 1, wherein: the flow velocity of the catalyst which is input into the capillary port and is subjected to pipe diameter reduction treatment is not less than 0.07 m/s, and the flow velocity of propylene is not less than 1 m/s.