Method for solving blockage of discharge line of prepolymerization reactor

Abstract

The invention provides a method for solving blockage of a discharge line of a prepolymerization reactor. The method comprises the following steps: isolating the prepolymerization reactor from a first loop reactor; discharging the first material in the prepolymerization reactor; filling liquid phase propylene into the prepolymerization reactor; discharging the second material in the prepolymerization reactor; and stopping isolating the prepolymerization reactor from the first loop reactor. The problem of blockage of the discharge line of the prepolymerization reactor can be conveniently solved, the material cost can be effectively reduced, and long-period normal operation of the prepolymerization reactor is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene process, and in particular to a method for solving the blockage of a discharge line of a prepolymerization reactor. Background Art

[0002] In the double loop polypropylene process, the prepolymerization reactor is connected to the first loop reactor through the prepolymerization reactor discharge line. In the actual production process, the prepolymerization reactor discharge line is affected by the finish of the pipeline, the flange connection gasket, and the finish of the discharge plunger valve channel, which increases the pressure of the prepolymerization reactor, thereby causing the prepolymerization reactor to discharge poorly or even unable to discharge. The equipment needs to be shut down on a large scale, and a long time is spent on repairing the prepolymerization reactor discharge line, which not only increases the material cost, but also affects the long-term operation of the prepolymerization reactor. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for solving the blockage of a discharge line of a prepolymerization reactor, by filling liquid propylene to generate a pressure difference between the inside and the outside of the prepolymerization reactor, and utilizing the pressure difference to discharge the attachments in the discharge line of the prepolymerization reactor, which can conveniently solve the problem of blockage of the discharge line of the prepolymerization reactor without large-scale shutdown of the equipment, effectively reduce material costs, and ensure that the prepolymerization reactor can operate normally for a long period of time.

[0004] In a first aspect, an embodiment of the present invention provides a method for solving the blockage of a discharge line of a prepolymerization reactor, characterized in that it comprises:

[0005] Step 1: isolating the prepolymerization reactor from the first loop reactor;

[0006] Preferably, the transmission of the three feeds, the propylene feed, to the prepolymerization reactor is stopped;

[0007] Step 2: discharging the first material in the prepolymerization reactor;

[0008] Preferably, discharging the first material in the prepolymerization reactor to a low-pressure flare system;

[0009] Step 3: filling the prepolymerization reactor with liquid propylene to make the interior of the prepolymerization reactor reach a first operating pressure, and discharging the second material in the prepolymerization reactor;

[0010] Wherein, the second material includes the liquid propylene and the attachments in the discharge line of the prepolymerization reactor;

[0011] Preferably, the steps of charging the prepolymerization reactor with the liquid propylene to make the interior of the prepolymerization reactor reach the first operating pressure and discharging the second material in the prepolymerization reactor are repeated;

[0012] Preferably, the second material in the prepolymerization reactor is discharged to a low-pressure flare system;

[0013] Step 4: stopping and isolating the prepolymerization reactor and the first loop reactor;

[0014] Preferably, after the isolation of the prepolymerization reactor and the first loop reactor is stopped, the hand valve of the discharge plunger valve is opened, and when the interior of the prepolymerization reactor reaches the second operating pressure, the hand valve of the discharge plunger valve is closed.

[0015] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic flow chart of a method for solving the blockage of a discharge line of a prepolymerization reactor provided by an embodiment of the present invention;

[0019] Figure 2 A working principle diagram of a method for solving the blockage of a discharge line of a prepolymerization reactor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] A method for solving the blockage of a discharge line of a prepolymerization reactor provided in an embodiment of the present invention can discharge attachments in the discharge line of the prepolymerization reactor without stopping the operation, thereby solving the blockage problem of the discharge line of the prepolymerization reactor.

[0022] To facilitate understanding of this embodiment, Figure 1 A method for solving the blockage of a discharge line of a prepolymerization reactor disclosed in an embodiment of the present invention is introduced in detail.

[0023] Embodiment 1:

[0024] A method for solving the blockage of a discharge line of a prepolymerization reactor disclosed in an embodiment of the present invention comprises the following specific steps:

[0025] Step 1: isolating the prepolymerization reactor from the first loop reactor;

[0026] Specifically, the internal operator starts the interlocking system, and the external operator closes the hand valve of the discharge plunger valve to isolate the prepolymerization reactor from the first loop reactor; wherein the interlocking system is used to control, after startup, including but not limited to the prepolymerization reactor, the first loop reactor, the discharge plunger valve, the regulating valve, and the discharge valve; the hand valve of the discharge plunger valve is installed at one end of the discharge line of the prepolymerization reactor, and is located inside the first loop reactor;

[0027] Preferably, the transmission of the three feeds, the propylene feed, to the prepolymerization reactor is stopped;

[0028] Step 2: discharging the first material in the prepolymerization reactor;

[0029] Specifically, the external operator opens the hand valve of the discharge valve at the bottom of the prepolymerization reactor to discharge the first material in the prepolymerization reactor; wherein the first material is the remaining material in the prepolymerization reactor, including polypropylene slurry and three agents;

[0030] Preferably, discharging the first material in the prepolymerization reactor to a low-pressure flare system;

[0031] Step 3: filling the prepolymerization reactor with liquid propylene to make the interior of the prepolymerization reactor reach the first operating pressure, and discharging the second material in the prepolymerization reactor;

[0032] Specifically, the external operator fills the prepolymerization reactor with liquid propylene through the cross-line of the regulating valve of the propylene feed until the interior of the prepolymerization reactor reaches the first operating pressure; when the interior of the prepolymerization reactor reaches the first operating pressure, the external operator opens the manual valve of the discharge valve at the bottom of the prepolymerization reactor, and at this time, a pressure difference is generated between the interior of the prepolymerization reactor and the exterior of the prepolymerization reactor, so that the second material can be discharged through the discharge valve; wherein the second material includes liquid propylene and attachments in the discharge line of the prepolymerization reactor;

[0033] Preferably, the operation of charging the prepolymerization reactor with liquid propylene to make the interior of the prepolymerization reactor reach the first operating pressure, and discharging the second material in the prepolymerization reactor is repeated; illustratively, the number of repetitions is 2 to 3 times;

[0034] Preferably, the second material in the prepolymerization reactor is discharged to a low-pressure flare system;

[0035] Step 4: stopping and isolating the prepolymerization reactor and the first loop reactor;

[0036] Specifically, the internal operator resets the interlock system, at which time the discharge valve at the bottom of the prepolymerization reactor is closed, the isolation between the prepolymerization reactor and the first loop reactor is stopped, and the cleaning of the discharge line of the prepolymerization reactor is completed;

[0037] Preferably, after the prepolymerization reactor and the first loop reactor are stopped from being isolated, the hand valve of the discharge plunger valve is opened, and when the interior of the prepolymerization reactor reaches the second operating pressure, the hand valve of the discharge plunger valve is closed;

[0038] Specifically, after the isolation of the prepolymerization reactor and the first loop reactor is stopped, the external operator opens the manual valve of the discharge plunger valve, and when the interior of the prepolymerization reactor reaches the second operating pressure, the manual valve of the discharge plunger valve is closed; wherein, by switching the manual valve of the discharge plunger valve, the attachments in the valve body channel of the discharge plunger valve can be cleaned.

[0039] Embodiment 2:

[0040] In order to enable those skilled in the art to better and more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments. The specific steps are as follows:

[0041] Taking a 100,000 ton / year polypropylene plant as an example, combined with Figure 2, the internal operator starts the interlock system IS202, and the external operator closes the hand valve HV2203A of the discharge plunger valve to isolate the prepolymerization reactor R200 from the first loop reactor R201, and at the same time stops transmitting the three-dose feed and propylene feed to the prepolymerization reactor R200. At this time, the pressure in the prepolymerization reactor R200 is about 3.8MPa;

[0042] The external operator opens the discharge valve HV2203B at the bottom of the prepolymerization reactor R200 to discharge the remaining polypropylene slurry and three agents in the prepolymerization reactor R200 to the low-pressure flare system. At this time, the pressure in the prepolymerization reactor R200 is 0 MPa;

[0043] The external operator fills the prepolymerization reactor R200 with liquid propylene through the cross-line of the propylene feed regulating valves FV2004 and FV2201 until the prepolymerization reactor R200 reaches an operating pressure of 4.0 MPa. At this time, the liquid propylene and the attachments in the discharge line of the prepolymerization reactor are all discharged to the low-pressure flare system;

[0044] The above operation of charging the prepolymerization reactor R200 with liquid propylene and discharging the liquid propylene in the prepolymerization reactor R200 was repeated 3 times;

[0045] The internal operator resets the interlock system IS202. At this time, the discharge valve HV2203B at the bottom of the prepolymerization reactor R200 is closed. The external operator closes the hand valve of the discharge plunger valve HV2203A. After the pressure in the prepolymerization reactor R200 rises to 4.2MPa, the hand valve of the discharge plunger valve HV2203A is quickly opened. At this time, the pressure in the prepolymerization reactor R200 is about 3.5MPa, and production operations can be carried out normally.

[0046] Among them, by completing the cleaning of the discharge line of the prepolymerization reactor and the cleaning of the attachments in the valve body channel of the discharge plunger valve, the propylene loss can be reduced by 10 tons, and the propylene cost can be saved by about 56,800 yuan; the replacement nitrogen loss can be reduced by 40,000 standard cubic meters, and the nitrogen cost can be saved by about 40,000 yuan; based on the benefit of 450 yuan / ton of polypropylene, the loss of 540,000 yuan can be avoided in 96 hours, and the total cost saving is 636,800 yuan.

[0047] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for solving the blockage of the discharge line of a prepolymerization reactor, characterized in that: include: Step 1: isolating the prepolymerization reactor from the first loop reactor; Step 2: discharging the first material in the prepolymerization reactor; Step 3: filling the prepolymerization reactor with liquid propylene to make the interior of the prepolymerization reactor reach a first operating pressure, and discharging the second material in the prepolymerization reactor; Wherein, the second material includes the liquid propylene and the attached materials in the discharge line of the prepolymerization reactor; Step 4: stopping and isolating the prepolymerization reactor and the first loop reactor.

2. A method for solving the blockage of the discharge line of a prepolymerization reactor according to claim 1, characterized in that: The isolating of the prepolymerization reactor from the first loop reactor in step 1 further comprises: The delivery of the third feed, propylene feed, to the prepolymerization reactor was stopped.

3. A method for solving the blockage of the discharge line of a prepolymerization reactor according to claim 1, characterized in that: Discharging the first material in the prepolymerization reactor in step 2 comprises: The first material in the prepolymerization reactor is discharged to a low-pressure flare system.

4. A method for solving the blockage of the discharge line of a prepolymerization reactor according to claim 1, characterized in that: In step 3, the prepolymerization reactor is charged with liquid propylene to make the interior of the prepolymerization reactor reach a first operating pressure, and the second material in the prepolymerization reactor is discharged, characterized in that it also includes: The operations of charging the prepolymerization reactor with the liquid phase propylene to make the interior of the prepolymerization reactor reach the first operating pressure and discharging the second material in the prepolymerization reactor are repeated.

5. A method for solving the blockage of the discharge line of a prepolymerization reactor according to claim 1, characterized in that: Discharging the second material in the prepolymerization reactor in step 3 comprises: The second material in the prepolymerization reactor is discharged to a low-pressure flare system.

6. A method for solving the blockage of the discharge line of a prepolymerization reactor according to claim 1, characterized in that: After the prepolymerization reactor and the first loop reactor are stopped and isolated in step 4, the step further includes: The hand valve of the discharge plunger valve is opened, and when the interior of the prepolymerization reactor reaches the second operating pressure, the hand valve of the discharge plunger valve is closed.

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