System and method for producing impact-resistant co-polypropylene

Abstract

The invention belongs to the technical field of olefin gas-phase polymerization, and discloses a system and a method for producing impact-resistant co-polypropylene, the system comprises an intermittent polypropylene device and a gas supply tank, the intermittent polypropylene device comprises a polymerization kettle, the gas outlet of the gas supply tank is connected with the gas inlet of the polymerization kettle through a gas-phase olefin feeding pipeline, and the gas inlet of the polymerization kettle is communicated with the gas-phase olefin feeding pipeline. A gas outlet of the polymerization kettle is connected with a gas supply tank through a circulating gas pipeline; the gas supply tank is connected with a propylene feeding unit and an ethylene feeding unit, the gas supply tank is provided with a temperature control unit and a first pressure control unit, and the circulating gas pipeline is provided with a circulating compressor. According to the system and the method disclosed by the invention, under the condition of small equipment investment, the production of the impact-resistant co-polypropylene product by the intermittent liquid phase bulk process device is realized, and the quality of polypropylene can be ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin polymerization, and in particular relates to a system and method for producing impact-resistant copolymerized polypropylene. Background Art

[0002] Impact copolymer polypropylene, also known as multiphase copolymer polypropylene, is a high value-added product in the polypropylene family due to its good balance of rigidity and toughness. Its output has always maintained a strong growth trend. The developed grades are increasingly replacing steel and engineering plastics and are widely used in the automotive, home appliances and other fields.

[0003] The preparation of impact-resistant polypropylene is based on a multi-reactor series process. First, propylene is homopolymerized in the first-stage reactor to generate an isotactic polypropylene continuous phase. Then, the polymer particles are transferred to the subsequent reactor for ethylene / propylene or ethylene / butene copolymerization to generate a dispersed phase copolymer on the continuous phase isotactic polypropylene. Currently, impact-resistant copolymer polypropylene can basically only be produced in a continuous polypropylene process.

[0004] The intermittent liquid phase bulk polypropylene production technology is a technology successfully developed by my country. The process mainly includes process units such as raw material refining, polymerization reaction, flash deactivation, granulation and packaging. The process unit of the polymerization reaction includes propylene metering tank, activator feeding tank, catalyst feeding tank, hydrogen metering tank, polymerization kettle, hot water tank, hot water pump, cold water pipeline and steam pipeline. The intermittent liquid phase bulk polypropylene process does not have very high requirements on the quality of raw material propylene, has a simple process, low investment, fast results, and flexible product brand conversion. It is particularly suitable for the characteristics and national conditions of my country's dispersed and abundant refinery gas resources. The intermittent liquid phase bulk method can generally only produce homopolymer polypropylene.

[0005] Patent document CN101693756A discloses a production process and device of block copolymer polypropylene, and the production process flow is: liquid phase propylene is polymerized in a homopolymerization kettle to generate homopolymer polypropylene, and after polymerization, it is transferred from the liquid phase homopolymerization kettle to a copolymerization gas phase kettle, and after the surface of polypropylene particles is inactivated, ethylene and propylene are introduced to carry out gas phase copolymerization with polypropylene to generate block copolymer polypropylene. The production device includes a polymerization system, a gas distribution system, a low-purity nitrogen system, a degassing flash distillation system and a circulation system. The method makes the production of intermittent liquid-gas phase method block copolymer polypropylene a reality. However, there is no description of how to control the gas composition in the polymerization kettle during the gas phase copolymerization of ethylene and propylene in the patent document, so the quality stability of the block copolymer prepared will be affected. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a system and method for producing impact copolymer polypropylene, so as to improve the situation that intermittent polypropylene devices have low-end products and poor profitability, and to increase product added value and market competitiveness.

[0007] A first aspect of the present invention provides a system for producing impact copolymer polypropylene, the system comprising an intermittent polypropylene device and a gas supply tank, the intermittent polypropylene device comprising a polymerization kettle, the gas outlet of the gas supply tank being connected to the gas inlet of the polymerization kettle via a gas-phase olefin feed pipeline, and the gas outlet of the polymerization kettle being connected to the gas supply tank via a circulating gas pipeline;

[0008] The gas supply tank is connected with a propylene feed unit and an ethylene feed unit, the gas supply tank is provided with a temperature control unit and a first pressure control unit, and the circulating gas pipeline is provided with a circulating compressor.

[0009] A second aspect of the present invention provides a method for producing impact copolymer polypropylene using the above system, the method comprising:

[0010] 1) The propylene feed unit introduces liquid propylene into the gas supply tank, the gas supply tank is heated, and the liquid propylene is partially gasified; the ethylene feed unit introduces gaseous ethylene into the gas supply tank, and the temperature and pressure of the gas supply tank are controlled to make the gasified liquid propylene and gaseous ethylene form a copolymerized mixed olefin gas;

[0011] 2) adding materials containing liquid propylene and a catalyst system into a polymerization kettle to carry out a propylene homopolymerization reaction, and after the homopolymerization reaction is completed, flashing and recovering unreacted propylene monomer;

[0012] 3) introducing the mixed olefin gas into the polymerization kettle, and circulating the gas between the polymerization kettle and the gas supply tank through a circulation compressor, the polymerization kettle performs copolymerization reaction, as the copolymerization reaction proceeds, gas phase ethylene is continuously introduced into the gas supply tank, liquid phase propylene is continuously gasified, and the temperature and pressure of the gas supply tank are maintained the same as in step 1);

[0013] 4) After the copolymerization reaction is completed, the pressure of the polymerization kettle is gradually reduced, the gas circulation is stopped, the gas inlet and outlet of the polymerization kettle are closed, the polymerization product is discharged and post-processed to obtain impact copolymer polypropylene.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) For the copolymerization reaction of olefins, the different consumption rates of different olefin monomers in the polymerization kettle caused by the difference in the reactivity ratio of different olefin monomers bring difficulties to the stable control of the gas composition during the olefin copolymerization process. In the system of the present invention, the gas supply tank can provide a mixed gas of propylene and ethylene with a stable composition; by adding a circulating compressor between the polymerization kettle and the gas supply tank and selecting a suitable circulating gas speed, the gas between the polymerization kettle and the gas distribution tank is circulated, which achieves the effect of maintaining the basic stability of the gas composition in the polymerization kettle on the one hand, and also achieves the purpose of assisting the withdrawal of polymerization heat on the other hand, which is beneficial to the temperature control of the polymerization kettle during gas phase polymerization.

[0016] (2) The system and method for producing impact-resistant copolymer polypropylene of the present invention can realize the production of impact-resistant copolymer polypropylene products by an intermittent liquid phase bulk process device with relatively small equipment investment. Compared with the prior art, both process control and product performance can be optimized, thereby improving the situation of low-end products and poor profitability of intermittent polypropylene devices and improving product added value and market competitiveness.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a system for producing impact copolymer polypropylene.

[0019] Explanation of the reference numerals: 1-propylene storage tank; 2-propylene pump; 3-polymerization kettle; 4-hydrogen cylinder; 5-hydrogen feed pressure reducing valve; 6-additive feeding port; 7-high-pressure ethylene cylinder; 8-ethylene feed pressure reducing valve; 9-ethylene feed regulating valve; 10-gas supply tank; 11-propylene feed regulating valve; 12-gas supply tank outlet pressure reducing valve; 13-mixed gas inlet regulating valve; 14-circulating compressor; 15-heat exchanger; 16-deactivation tank; 17-propylene recovery system. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0021] According to a first aspect of the present invention, the present invention provides a system for producing impact copolymer polypropylene, the system comprising an intermittent polypropylene device and a gas supply tank, the intermittent polypropylene device comprising a polymerization kettle, the gas outlet of the gas supply tank is connected to the gas inlet of the polymerization kettle through a gas-phase olefin feed pipeline, and the gas outlet of the polymerization kettle is connected to the gas supply tank through a circulating gas pipeline;

[0022] The gas supply tank is connected with a propylene feed unit and an ethylene feed unit, the gas supply tank is provided with a temperature control unit and a first pressure control unit, and the circulating gas pipeline is provided with a circulating compressor.

[0023] The system of the present invention is realized by adding a gas supply tank to the intermittent polypropylene device. The intermittent polypropylene device is a conventional setting in the art, such as containing a polymerization kettle, a propylene feeding facility, a propylene recovery system, etc., which will not be described in detail here. The gas supply tank of the present invention provides the polymerization kettle with propylene and ethylene gas raw materials of a specific composition required for copolymerization. There is no strict requirement for the size of the gas supply tank. Generally, the volume ratio of the gas supply tank to the polymerization kettle is 0.01 to 5:1, preferably 0.05 to 0.5:1.

[0024] According to the present invention, the propylene feed unit provides liquid olefin raw materials to the gas supply tank intermittently or continuously. If the pressure of the propylene source is lower than the operating pressure of the gas supply tank, the feed unit can use an explosion-proof diaphragm pump as a conveying power device; if the pressure of the propylene source is higher than the operating pressure of the gas supply tank, the feed unit can use the pressure difference to realize raw material transportation without the need for additional power equipment. The gas supply tank is provided with a liquid level meter, and a third regulating valve is provided on the connecting pipeline between the propylene feed unit and the gas supply tank. The third regulating valve is electrically connected to the liquid level meter signal of the gas supply tank to realize continuous feeding of liquid olefins. The propylene feed unit can be a propylene feeding facility shared with an intermittent polypropylene device.

[0025] In the present invention, the ethylene feed unit continuously supplies ethylene gas to the gas supply tank. The pressure of the ethylene source is higher than the use pressure of the gas supply tank. The gas supply tank is provided with a pressure meter, and the first pressure control unit is a pressure reducing valve (such as a self-operated pressure reducing valve) and / or a first regulating valve provided on the pipeline connecting the ethylene feed unit and the gas supply tank. The first regulating valve is electrically connected to the pressure meter signal of the gas supply tank to stabilize the pressure of the gas supply tank at a set value.

[0026] According to the present invention, the gas supply tank is provided with a temperature meter, and the temperature control unit maintains the temperature of the material in the gas supply tank near the set value of the gas supply tank. The temperature control unit may include a jacket water system provided on the outer surface of the gas supply tank and / or a heat exchanger provided on the circulating gas return pipeline.

[0027] The jacket water system is a conventional temperature control system, which includes an instrument for controlling the jacket water temperature and flow rate, so that the temperature of the gas supply tank can be maintained within a certain range of the set temperature value. The heat exchange medium of the heat exchanger is circulating water.

[0028] According to a specific embodiment, the temperature control unit only includes a heat exchanger arranged on the circulating gas pipeline, and a crossover line is connected between the gas-phase olefin feed pipeline and the circulating gas pipeline. The heat exchanger includes an instrument for controlling the flow and temperature of the heat exchange medium. The setting of the crossover line allows the circulating gas to circulate only between the gas supply tank, the circulating compressor and the heat exchanger, thereby realizing the temperature control of the material in the gas supply tank. These can be realized by referring to the existing technology.

[0029] In the present invention, the circulating compressor is the power source for realizing the circulation of the reaction gas between the polymerization kettle and the gas supply tank, and a centrifugal compressor can generally be selected.

[0030] According to the present invention, the gas phase olefin feed pipeline is provided with a second pressure control unit, which includes a pressure reducing valve and / or a second regulating valve, and the second regulating valve is electrically connected to the pressure instrument signal of the polymerization kettle.

[0031] According to a second aspect of the present invention, the present invention provides a method for producing impact copolymer polypropylene using the above system, the method comprising:

[0032] 1) The propylene feed unit introduces liquid propylene into the gas supply tank, the gas supply tank is heated, and the liquid propylene is partially gasified; the ethylene feed unit introduces gaseous ethylene into the gas supply tank, and the temperature and pressure of the gas supply tank are controlled to make the gasified liquid propylene and gaseous ethylene form a copolymerized mixed olefin gas;

[0033] 2) adding materials containing liquid propylene and a catalyst system into a polymerization kettle to carry out a propylene homopolymerization reaction, and after the homopolymerization reaction is completed, flashing and recovering unreacted propylene monomer;

[0034] 3) introducing the mixed olefin gas into the polymerization kettle, and circulating the gas between the polymerization kettle and the gas supply tank through a circulation compressor, the polymerization kettle performs copolymerization reaction, as the copolymerization reaction proceeds, gas phase ethylene is continuously introduced into the gas supply tank, liquid phase propylene is continuously gasified, and the temperature and pressure of the gas supply tank are maintained the same as in step 1);

[0035] 4) After the copolymerization reaction is completed, the pressure of the polymerization kettle is gradually reduced, the gas circulation is stopped, the gas inlet and outlet of the polymerization kettle are closed, the polymerization product is discharged and post-processed to obtain impact copolymer polypropylene.

[0036] In the present invention, the temperature, pressure and liquid propylene volume of the gas supply tank can be determined as needed, as long as the copolymerized mixed olefin gas can be continuously provided. For example, the liquid volume in the gas supply tank accounts for 10% to 90% of the volume of the gas supply tank, the temperature of the gas supply tank is 0 to 50°C, and the pressure of the gas supply tank is 0.5 to 4.0 MPa.

[0037] According to the present invention, the feed of liquid propylene to the gas supply tank can be introduced only once before copolymerization and not introduced again during the copolymerization process; it can also be introduced intermittently for multiple times during the copolymerization process; or it can be continuously introduced during the whole process through the automatic control of the regulating valve and the liquid level of the gas supply tank. Preferably, the regulating valve is electrically connected to the liquid level instrument signal of the gas supply tank, and the liquid propylene is continuously introduced into the gas supply tank, so that the liquid level of the gas supply tank is constant at the set value.

[0038] In the present invention, the pressure of the final polymerization kettle after the homopolymerization reaction is completed and propylene is recovered by flash evaporation will affect the establishment of the initial equilibrium of the subsequent ethylene-propylene copolymerization, so the pressure should be as low as possible, and its selection depends on the capacity of the propylene recovery system. Generally, after the homopolymerization reaction is completed, when the pressure of the polymerization kettle is lower than 2.0MPa, the flash evaporation is stopped; preferably, when it is lower than 1.0MPa, the flash evaporation is stopped.

[0039] According to the present invention, during the copolymerization reaction, the temperature of the material in the gas supply tank fluctuates less than 10° C., preferably less than 5° C., and more preferably less than 2° C. relative to the set temperature of the gas supply tank. The temperature of the material in the gas supply tank is the actual temperature displayed on the temperature monitoring instrument.

[0040] In the present invention, hydrogen needs to be introduced during homopolymerization and copolymerization, which is a conventional operation in the art, and the amount of hydrogen can also be selected as required. The conditions for homopolymerization can also refer to the conventional conditions in the prior art.

[0041] According to the present invention, the circulating gas flow rate of the circulating compressor during the copolymerization process should be as large as possible, which is conducive to the stability of the gas composition in the polymerization kettle and the withdrawal of polymerization heat, but the corresponding equipment cost will also increase. The circulating compressor gas speed is selected according to the size of the polymerization kettle, generally 1 to 80m 3 / min.

[0042] In the present invention, the copolymerization temperature is 50-100° C., and the copolymerization pressure is 0.1-2.0 MPa. The higher the copolymerization pressure, the higher the polymerization rate. However, the copolymerization pressure must be lower than the pressure of the gas supply tank.

[0043] According to the present invention, after the copolymerization reaction is completed, the pressure of the polymerization kettle is gradually reduced, which can be achieved by gradually reducing the flow rate of the reaction gas entering the polymerization kettle from the gas supply tank, and the gas speed of the circulating compressor can remain unchanged. The pressure value of the polymerization kettle after the reduction can make the polymerization kettle discharge smoothly. Generally, after the copolymerization reaction is completed, when the pressure of the polymerization kettle is lower than 1.0MPa, the gas circulation is stopped; preferably, when it is lower than 0.5MPa, the gas circulation is stopped. The impact-resistant copolymerized polypropylene obtained by polymerization is discharged to the deactivation tank by utilizing the residual pressure in the polymerization kettle, and is packaged after nitrogen replacement and deactivation.

[0044] Components, components and parameters not limited in the present invention may be selected according to the prior art and belong to conventional technical means in the field.

[0045] The present invention will be further described below with reference to the following examples, but is not limited to these examples.

[0046] Example

[0047] Process flow such as Figure 1 As shown. The system for producing impact-resistant copolymerized polypropylene includes an intermittent polypropylene device and a gas supply tank 10. The intermittent polypropylene device includes a polymerization kettle 3. The gas outlet of the gas supply tank is connected to the gas inlet of the polymerization kettle through a gas-phase olefin feed pipeline, and the gas outlet of the polymerization kettle is connected to the gas supply tank through a circulating gas pipeline. The gas supply tank is connected to a propylene feed unit (propylene storage tank 1) and an ethylene feed unit (high-pressure ethylene cylinder 7). The gas supply tank is provided with a temperature control unit and a first pressure control unit, and a circulating compressor 14 is provided on the circulating gas pipeline. A temperature meter is provided on the gas supply tank, and the temperature control unit includes a heat exchanger 15 provided on the circulating gas pipeline. A crossover line is connected between the gas-phase olefin feed pipeline and the circulating gas pipeline. A pressure meter is provided on the gas supply tank, and the first pressure control unit includes an ethylene feed pressure reducing valve 8 and an ethylene feed regulating valve 9 provided on the connecting pipeline between the ethylene feed unit and the gas supply tank. The ethylene feed regulating valve is electrically connected to the pressure meter signal of the gas supply tank. A second pressure control unit is provided on the gas phase olefin feed pipeline, and the second pressure control unit includes a gas supply tank outlet pressure reducing valve 12 and a mixed gas inlet kettle regulating valve 13, and the mixed gas inlet kettle regulating valve is electrically connected to the pressure instrument signal of the polymerization kettle. A liquid level meter is provided on the gas supply tank, and a propylene feed regulating valve 11 is provided on the connecting pipeline between the propylene feed unit and the gas supply tank, and the propylene feed regulating valve is electrically connected to the liquid level instrument signal of the gas supply tank.

[0048] The specific process steps include: the volume of the gas supply tank is 2 liters, the liquid level of the gas supply tank 10 is set to 50%, and its liquid level is automatically connected with the opening of the propylene feed regulating valve 11, and then the liquid phase propylene is continuously introduced into the gas supply tank 10 from the propylene storage tank 1 through the propylene pump 2. The temperature value of the gas supply tank 10 is set to 30°C, and its temperature is cascade-controlled with the circulating water temperature of the heat exchanger 15, and the circulating gas compressor is started to heat the gas supply tank. After the temperature of the gas supply tank 10 reaches the set value and stabilizes, the pressure value of the gas supply tank 10 is set to 1.75MPa, and its pressure value is automatically connected with the opening of the ethylene feed regulating valve 9, and then ethylene gas is continuously introduced into the gas supply tank from the high-pressure ethylene cylinder 7 through the ethylene feed pressure reducing valve 8 and the ethylene feed regulating valve 9.

[0049] The polymerization kettle is a 5-liter reactor. 3.0 mmol of triethyl aluminum, 0.3 mmol of external electron donor cyclohexylmethyldimethoxysilane, and 12.0 mg of DQ catalyst are added to the polymerization kettle 3 through the auxiliary agent feeding port 6; then 0.25 g of hydrogen is added to the polymerization kettle 3 from the hydrogen cylinder 4 through the hydrogen feed pressure reducing valve 5; finally, 2.5 liters of liquid propylene is added to the polymerization kettle 3 from the propylene storage tank 1 through the propylene pump 2, and the temperature is raised to 70° C. under stirring, and the liquid propylene is polymerized in the polymerization kettle for 60 minutes to generate homopolymerized polypropylene, and then the unreacted propylene in the polymerization kettle is recovered through the propylene recovery system 17.

[0050] After the pressure of the polymerization kettle 3 is lower than 0.5MPa, the propylene recovery valve is closed, the gas inlet and outlet valves on the polymerization kettle 3 are opened, and then the valve on the cross-line is closed, 0.05g of hydrogen is added to the polymerization kettle, and finally the polymerization kettle temperature is set to 70°C and the pressure value is 1.4MPa, and the polymerization kettle pressure value and the opening of the mixed gas inlet regulating valve 13 are automatically turned on to make the ethylene and propylene copolymerization reaction in the polymerization kettle 3. The copolymerization time is 60 minutes, and gas samples are taken from the polymerization kettle at the beginning, 20th minute, 40th minute and before the end of the copolymerization.

[0051] After the copolymerization is completed, the pressure of the polymerization kettle is gradually reduced until the pressure of the polymerization kettle is 0.3 MPa, the air inlet and outlet valves on the polymerization kettle 3 are closed, and the discharge valve from the polymerization kettle 3 to the deactivation tank 16 is opened to discharge the generated impact copolymer polypropylene to the deactivation tank 16. The polypropylene product in the deactivation tank 16 can be discharged and packaged after nitrogen replacement and deactivation.

[0052] During the copolymerization process, the temperature of the polymerization kettle can be stably controlled, and 505 grams of polymer are finally obtained. The polymer is analyzed and tested, and the ethylene mass content is 12.38%, and the rubber phase mass content is 26.39%. The results of gas sample chromatographic analysis are shown in Table 1.

[0053] Comparative Example

[0054] The difference from the embodiment is that: after the pressure of the polymerizer 3 is lower than 0.1MPa, the propylene recovery valve is closed, the pressure of the polymerizer is released to normal pressure by venting, the mixed gas inlet regulating valve 13 is adjusted to 100%, the air inlet valve on the polymerizer 3 is opened, and the air outlet valve on the polymerizer 3 is kept closed, and the ethylene-propylene mixed gas is introduced into the polymerizer, and then 0.05 grams of hydrogen is added, the temperature of the polymerizer is set to 70°C, and the pressure reducing valve 12 at the outlet of the gas supply tank is adjusted to make the pressure of the polymerizer reach 1.4MPa, and the copolymerization reaction is started for 60 minutes. Gas samples are taken from the polymerizer at the beginning, 20th minute, 40th minute and before the end of the copolymerization. After the copolymerization is completed, the air inlet valve on the polymerizer is closed, the pressure of the polymerizer is released to 0.3MPa, the unloading valve from the polymerizer 3 to the deactivation tank 16 is opened, and the generated impact-resistant copolymerized polypropylene is discharged to the deactivation tank 16, and released after displacement and deactivation. The rest is the same as Example 1.

[0055] During the copolymerization process, the temperature of the polymerization kettle could not be stably controlled. The maximum temperature rose to 96°C in the initial stage, and gradually decreased in the later stage, but was still as high as 82°C at the end. Finally, 478 grams of polymer were obtained. The polymer was analyzed and tested, and the ethylene mass content was 10.25% and the rubber phase mass content was 25.01%. The results of gas sample chromatographic analysis are shown in Table 1.

[0056] Table 1

[0057]

[0058] As shown in Table 1, the volume ratio of ethylene to propylene in the polymerization kettle during the copolymerization process is very stable in the system and method of the present invention, and the variation range is within 2%, which is beneficial to improving the quality of the polymer product. In the comparative example, the volume ratio of ethylene to propylene in the polymerization kettle during the copolymerization process continues to decrease, and the gas composition at the end of the gas phase polymerization is compared with that at the beginning, and the volume ratio of ethylene to propylene is reduced by 43%. The system and method for producing impact-resistant copolymerized polypropylene of the present invention can improve the situation of low-end products and poor profitability of intermittent polypropylene devices, and improve product added value and market competitiveness.

[0059] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A system for producing impact copolymer polypropylene, characterized in that: The system comprises an intermittent polypropylene device and a gas supply tank, wherein the intermittent polypropylene device comprises a polymerization kettle, the gas outlet of the gas supply tank is connected to the gas inlet of the polymerization kettle through a gas-phase olefin feed pipeline, and the gas outlet of the polymerization kettle is connected to the gas supply tank through a circulating gas pipeline; The gas supply tank is connected with a propylene feed unit and an ethylene feed unit, the gas supply tank is provided with a temperature control unit and a first pressure control unit, and the circulating gas pipeline is provided with a circulating compressor.

2. The system for producing impact copolymer polypropylene according to claim 1, wherein: The gas supply tank is provided with a temperature meter, and the temperature control unit includes a jacket water system provided on the outer surface of the gas supply tank and / or a heat exchanger provided on the circulating gas pipeline; Preferably, the temperature control unit comprises a heat exchanger arranged on the circulating gas pipeline, and a jumper is connected between the gas-phase olefin feed pipeline and the circulating gas pipeline.

3. The system for producing impact copolymer polypropylene according to claim 1, wherein: The gas supply tank is provided with a pressure meter, and the first pressure control unit includes a pressure reducing valve and / or a first regulating valve provided on the pipeline connecting the ethylene feed unit and the gas supply tank, and the first regulating valve is electrically connected to the pressure meter signal of the gas supply tank.

4. The system for producing impact copolymer polypropylene according to claim 1, wherein: The gas-phase olefin feed pipeline is provided with a second pressure control unit, which includes a pressure reducing valve and / or a second regulating valve, and the second regulating valve is electrically connected to the pressure instrument signal of the polymerization kettle.

5. The system for producing impact copolymer polypropylene according to claim 1, wherein: The gas supply tank is provided with a liquid level meter, and a third regulating valve is provided on the connecting pipeline between the propylene feed unit and the gas supply tank. The third regulating valve is electrically connected to the liquid level meter signal of the gas supply tank.

6. A method for producing impact copolymer polypropylene using the system according to any one of claims 1 to 5, characterized in that: The method includes: 1) The propylene feed unit introduces liquid propylene into the gas supply tank, the gas supply tank is heated, and the liquid propylene is partially gasified; the ethylene feed unit introduces gaseous ethylene into the gas supply tank, and the temperature and pressure of the gas supply tank are controlled to make the gasified liquid propylene and gaseous ethylene form a copolymerized mixed olefin gas; 2) adding materials containing liquid propylene and a catalyst system into a polymerization kettle to carry out a propylene homopolymerization reaction, and after the homopolymerization reaction is completed, flashing and recovering unreacted propylene monomer; 3) introducing the mixed olefin gas into the polymerization kettle, and circulating the gas between the polymerization kettle and the gas supply tank through a circulation compressor, the polymerization kettle performs copolymerization reaction, as the copolymerization reaction proceeds, gas phase ethylene is continuously introduced into the gas supply tank, liquid phase propylene is continuously gasified, and the temperature and pressure of the gas supply tank are maintained the same as in step 1); 4) After the copolymerization reaction is completed, the pressure of the polymerization kettle is gradually reduced, the gas circulation is stopped, the gas inlet and outlet of the polymerization kettle are closed, the polymerization product is discharged and post-processed to obtain impact copolymer polypropylene.

7. The method for producing impact copolymer polypropylene according to claim 6, wherein: After the homopolymerization reaction is completed, when the pressure in the polymerization kettle is lower than 2.0 MPa, preferably lower than 1.0 MPa, the flash evaporation is stopped.

8. The method for producing impact copolymer polypropylene according to claim 6, wherein: The volume of liquid in the gas supply tank accounts for 10% to 90% of the volume of the gas supply tank, the temperature of the gas supply tank is 0 to 50° C., and the pressure of the gas supply tank is 0.5 to 4.0 MPa.

9. The method for producing impact copolymer polypropylene according to claim 6, wherein: The air speed of the circulating compressor is 1~80m 3 / min.

10. The method for producing impact copolymer polypropylene according to claim 6, wherein: The temperature of the copolymerization reaction is 50-100° C., the pressure of the copolymerization reaction is 0.1-2.0 MPa, and the pressure of the copolymerization reaction is lower than the pressure of the gas supply tank.

11. The method for producing impact copolymer polypropylene according to claim 6, wherein: After the copolymerization reaction is completed, when the pressure in the polymerization reactor is lower than 1.0 MPa, preferably lower than 0.5 MPa, the gas circulation is stopped.

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