Safe and rapid sampling and hexane recovery system for polymer slurry in polyethylene production

Abstract

The utility model relates to the technical field of chemical production, and particularly discloses a safe and rapid sampling and hexane recovery system for polymer slurry in polyethylene production, which comprises a flash tank, a hexane blow-out tank, a flash filter and a protective filter, the powder output end of the flash tank is connected with the input end of the hexane blow-out tank, and the output end of the flash tank is connected with the input end of the hexane blow-out tank; a steel grating plate is arranged in the hexane blowing-out tank, and a V-shaped perforated distribution plate is arranged at the bottom of an inner cavity of the hexane blowing-out tank; through transformation, the aluminum alkyl can be prevented from catching fire due to contact with air during sampling, and dangers can be avoided; the working environment of staff of a detection department and the condition that the evaporation of hexane possibly pollutes the environment are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical production, and in particular relates to a system for safe and rapid sampling of polymer slurry and hexane recovery in polyethylene production. Background Art

[0002] The Hostal en ACP multi-reactor process can produce both unimodal and multimodal products. In the event of a production changeover, production anomalies, or abnormal quality of in-process or finished products, material from individual reactors must be sampled for testing of parameters such as melt index and density. The slurry sample (approximately 30% polyethylene resin content, approximately 69% hexane) is heated and evaporated by the testing department before testing for relevant parameters. Following standard testing methods, the testing department then provides feedback to the production department according to internal procedures. The production department then makes appropriate parameter adjustments based on the technical plan and other information, completing a quality control phase.

[0003] The Hostalen ACP process uses a titanium-based catalyst and an alkylaluminum co-catalyst. The alkylaluminum content in the reactor slurry is approximately 1 mmol / L. Directly transferring the slurry from the sampling port to the sample container during sampling can easily lead to fire and other hazardous events. The low vapor pressure of the solvent hexane makes complete evaporation difficult, and the hexane evaporation time at the testing center is relatively long (over 30 minutes). This increases the time between quality adjustments and time intervals; it also increases the cost of recovering the evaporated hexane and poses a risk of environmental pollution. Utility Model Content

[0004] The purpose of the utility model is to provide a safe and rapid sampling and hexane recovery system for polymer slurry in polyethylene production, so as to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A system for safe and rapid sampling and hexane recovery of polymer slurry in polyethylene production, comprising:

[0007] A flash tank, a hexane blow-out tank, a flash filter and a protective filter, wherein the powder output end of the flash tank is connected to the input end of the hexane blow-out tank, a steel grid plate is provided inside the hexane blow-out tank, and a V-shaped perforated distribution plate is provided at the bottom of the inner cavity of the hexane blow-out tank;

[0008] The input end includes a high-pressure flushing hexane input end, a low-pressure nitrogen input end, a low-pressure steam input end, and a reactor slurry input end. The high-pressure flushing hexane input end and the low-pressure steam input end are both connected to the flash tank, and the low-pressure nitrogen input end is connected to the bottom of the flash tank and the top and bottom of the hexane blow-off tank.

[0009] Preferably, the hexane output ends of the flash tank and the hexane blow-off tank are both connected to a protective filter.

[0010] Preferably, a flash filter is provided at the hexane output end of the flash tank, and a sampling port is provided at the bottom end of the hexane blow-out tank.

[0011] Preferably, the reactor slurry input end is further provided with a slurry cooler pump.

[0012] Preferably, the flash tank and the hexane blow-off tank are both provided with electric heating cables on the outside.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] (1) Through the transformation, the danger of alkyl aluminum catching fire when in contact with air during sampling can be avoided; the working environment of the testing department employees can be improved and the situation of evaporating hexane that may pollute the environment can be improved.

[0015] (2) Powder samples are collected through the sampling system, saving 10-15 minutes per sample. Assuming that the product type inspection indicators meet the standards after 20 hours of production conversion (approximately 20 samples), and an average load of approximately 30 tons / hour, the transition material consumption is expected to be reduced by 100 tons. The price difference between transition material and genuine material is calculated at 150 yuan / ton, and the conversion is expected to increase profits by 15,000 yuan.

[0016] (3) Recover the hexane evaporated from the testing department, saving costs and increasing efficiency. Taking a single powder sample of approximately 1 kg and removing approximately 2 kg of hexane, and considering the residual hexane in the powder and the rationality of the membrane recovery rate, the hexane recovery rate is calculated as 95%. This means that 57 kg of hexane can be saved during the conversion period. During normal production, approximately 12 samples are taken per day, saving approximately 22.8 kg of hexane per day, and approximately 7.5 tons of hexane per year (based on 330 days). The budgeted price of hexane is 7,000 yuan / ton, and the annual benefit of hexane recovery increases by 525,000 yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the overall structural diagram of the utility model;

[0018] In the figure: 1. Flash tank; 2. Hexane blow-off tank; 3. Flash filter; 4. Protective filter; 5. Steel grid plate; 6. V-shaped perforated distribution plate; 7. High-pressure flushing hexane input; 8. Low-pressure nitrogen input; 9. Low-pressure steam input; 10. Reactor slurry input; 11. Slurry cooler pump; 12. Electric heating tape; 13. Sampling port. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only 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 making creative efforts are within the scope of protection of the present invention.

[0020] Example 1:

[0021] See also Figure 1 As shown, a system for safe and rapid sampling and hexane recovery of polymer slurry in polyethylene production comprises:

[0022] Flash tank 1, hexane blow-out tank 2, flash filter 3 and protective filter 4. The powder output end of flash tank 1 is connected to the input end of hexane blow-out tank 2. A steel grid plate 5 is provided inside the hexane blow-out tank 2. A V-shaped perforated distribution plate 6 is provided at the bottom of the inner cavity of the hexane blow-out tank 2.

[0023] The input end includes a high-pressure flushing hexane input end 7, a low-pressure nitrogen input end 8, a low-pressure steam input end 9, and a reactor slurry input end 10. The high-pressure flushing hexane input end 7 and the low-pressure steam input end 9 are both connected to the flash tank 1, and the low-pressure nitrogen input end 8 is connected to the bottom of the flash tank 1 and the top and bottom of the hexane blow-off tank 2. The high-pressure flushing hexane input end 7 has different hexane pressures for flushing at positions with different operating pressures.

[0024] In one embodiment of the present invention, the hexane output ends of the flash tank 1 and the hexane blow-off tank 2 are both connected to the protection filter 4 .

[0025] In one embodiment of the present invention, a flash filter 3 is provided at the hexane output end of the flash tank 1 , and a sampling port 13 is provided at the bottom end of the hexane blow-out tank 2 .

[0026] In one embodiment of the present invention, the reactor slurry input end 10 is further provided with a slurry cooler pump 11 .

[0027] In one embodiment of the present invention, the flash tank 1 and the hexane blow-off tank 2 are both provided with electric heating cables 12 on the outside, and are also provided with insulation layers, the thickness of which is consistent with the unified material regulations, so that the tank bodies maintain a suitable temperature.

[0028] As can be seen from the above, a sampling point is set at the outlet of the slurry cooler pump 11 at the reactor slurry input end 10, and the reactor slurry, low-pressure hot nitrogen, high-pressure flushing hexane and low-pressure steam are input into the flash tank 1. The hot nitrogen is purged from the bottom of the flash tank 1. When most of the hexane in the flash tank 1 is evaporated, the generated powder continuously or discontinuously enters the inside of the hexane blow-out tank 2. The steel grid plate 5 removes possible block materials. The V-shaped perforated distribution plate 6 is at a special angle to the hexane blow-out tank 2. Nitrogen distribution facilities are arranged in the upper and lower directions of the V-shaped perforated distribution plate 6, so as to blow out nitrogen, help control the flow and distribution, and ensure that it acts evenly inside the equipment. After further removing the hexane, a powder sample is obtained, which can be taken out from the sampling port 13, and the evaporated hexane is filtered through the protective filter 4 and then enters the membrane recovery compressor to recover the hexane;

[0029] Hot nitrogen comes from the outlet of nitrogen heater (PTV);

[0030] The connection between the sampling port and the slurry material pipeline should be the same as the connection between the original sampling point and the main pipe before the pump inlet to prevent the powder from clogging the sampling port. After each sampling is completed, close the switch valve in front of the sample flash tank during the sampling process, and then flush with BHHX for 15 seconds.

[0031] The Hostal en ACP process is a multi-reactor process, and the sampling system configuration can be selected based on the number of reactors. Three sampling systems can be configured for three reactors, or a shared sampling system can be used for two reactors.

[0032] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for safe and rapid sampling of polymer slurry and hexane recovery in polyethylene production, characterized in that: include: A flash tank (1), a hexane blow-out tank (2), a flash filter (3) and a protective filter (4); the powder output end of the flash tank (1) is connected to the input end of the hexane blow-out tank (2); a steel grid plate (5) is provided inside the hexane blow-out tank (2); and a V-shaped perforated distribution plate (6) is provided at the bottom of the inner cavity of the hexane blow-out tank (2); The input end includes a high-pressure flushing hexane input end (7), a low-pressure nitrogen input end (8), a low-pressure steam input end (9), and a reactor slurry input end (10). The high-pressure flushing hexane input end (7) and the low-pressure steam input end (9) are both connected to the flash tank (1), and the low-pressure nitrogen input end (8) is connected to the bottom of the flash tank (1) and the top and bottom of the hexane blow-off tank (2).

2. The system for safe and rapid sampling and hexane recovery of polymer slurry in polyethylene production according to claim 1, characterized in that: The hexane output ends of the flash tank (1) and the hexane blow-off tank (2) are both connected to a protective filter (4).

3. The system for safe and rapid sampling and hexane recovery of polymer slurry in polyethylene production according to claim 1, characterized in that: The hexane output end of the flash tank (1) is provided with a flash filter (3), and the bottom end of the hexane blow-out tank (2) is provided with a sampling port (13).

4. The system for safe and rapid sampling of polymer slurry and hexane recovery in polyethylene production according to claim 1, characterized in that: The reactor slurry input end (10) is also provided with a slurry cooler pump (11).

5. The system for safe and rapid sampling and hexane recovery of polymer slurry in polyethylene production according to claim 1, characterized in that: The flash tank (1) and the hexane blowing tank (2) are both provided with electric heating cables (12) on the outside.

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