A device for optimizing and saving energy and reducing consumption of a propylene rectifying column system

Abstract

The utility model discloses a device of propylene rectification tower system optimization and energy -conserving and consumption -reducing, including propylene rectification tower, its characterized in that propylene rectification tower is in the upper part of original feed plate and is set up respectively in the lower part rectification section of the section of lifting the distillation, and the lower feed plate is set up, and the feed propylene is connected to the upper feed plate, the original feed plate and the lower feed plate through the upper feed valve, the middle feed valve, the lower feed valve respectively, the first connecting cross line is set up between propylene rectification tower overhead reflux line and side line production line, and the second connecting cross line is added to the overhead gas phase export, and is connected to propylene refrigeration compressor dry gas seal system main seal gas. The device increases the operation flexibility of rectification tower, reduces the energy consumption of device, improves the reliability of propylene compressor operation simultaneously.

Description

Technical Field

[0001] The utility model belongs to the technical field of olefin separation, and specifically relates to a device for optimizing a propylene rectification column system and achieving energy saving and consumption reduction. Background Art

[0002] The propylene rectification column plays a crucial role in industrial production, and is the key equipment for purifying propylene in olefin separation units. By utilizing the volatility difference of substances, propylene can be effectively separated from other components in the mixture. The propylene rectification column has a sophisticated structural design, including a stripping section, a rectification section and a condensation section, which ensures the efficient progress of the separation process. A pasteurization rectification section is arranged at the top of the propylene rectification column, where C2 and lighter components in the feed are removed and separated. Propylene product is extracted from the liquid phase of the side line of the trays below the pasteurization rectification section, so as to ensure that the light components in the propylene product do not exceed the standard. In the fields of petrochemical industry, chemical products, medicine and the like, the propylene rectification column is extremely widely applied, and it can improve the purity and quality of propylene, so as to guarantee its excellent application effect in subsequent production. In the production process of olefin separation units, the use of a propylene refrigeration compressor is also indispensable, which provides refrigeration capacity for separating ethylene, ethane and lighter components.

[0003] The propylene rectification column in the existing device has the following deficiencies in actual production: 1) When operating at full load, the separation efficiency of the propylene rectification column is at the critical limit. When the operation is affected by fluctuations in feed flow rate, feed composition or other factors, it is very likely that the products at the top and bottom of the column will fail to meet the specifications; 2) Affected by market and other factors, the economic benefit of the device is gradually decreasing, so it is necessary to optimize the system to save energy and reduce consumption; 3) When the concentration of C2 and lighter components in the feed is very low, the separation in the pasteurization rectification section is meaningless, which increases the energy consumption of the rectification column. At this time, the purity of the product extracted from the side line is even lower than that of the product extracted from the overhead reflux drum; 4] The dry gas seal system of the propylene refrigeration compressor supporting the device is provided with propylene gas and 2.0MPa nitrogen as main seal gas. When the dry gas seal is switched to high-pressure nitrogen during startup and shutdown or when the seal gas pressure fluctuates, the nitrogen entering the system will cause high pressure and cannot be condensed, resulting in pressure relief loss of propylene materials, which may cause the unit to shut down; in addition, some devices are not originally designed with a high-pressure nitrogen system, which requires separate configuration. Contents of the Invention

[0004] The purpose of the utility model is to provide a device for optimizing a propylene rectification column system and achieving energy saving and consumption reduction, so as to solve the problems existing in the actual operation of the propylene rectification column. By optimizing the propylene rectification column system, the operation flexibility is increased, energy is saved and consumption is reduced, meanwhile, the operation reliability of the propylene compressor is improved, and the maximization of the operation benefit of the device is achieved.

[0005] To achieve the above-mentioned objectives, this utility model provides a device for optimizing and saving energy in a propylene distillation tower system, comprising a propylene distillation tower. The propylene distillation tower is characterized by having upper and lower feed plates respectively installed in the stripping section above the original feed plate and the rectification section below the original feed plate. The propylene feed is connected to the upper feed plate, the original feed plate, and the lower feed plate respectively through an upper feed valve, a middle feed valve, and a lower feed valve. A first connecting cross-line is installed between the top reflux line and the side outlet line of the propylene distillation tower, and a second connecting cross-line is added to the top gas phase outlet, connecting to the main sealing gas of the dry gas sealing system of the propylene refrigeration compressor.

[0006] Furthermore, the position of the upper feed plate differs from that of the original feed plate by 6 to 10 trays.

[0007] Furthermore, the position of the lower feed plate differs from that of the original feed plate by 6 to 10 trays.

[0008] Furthermore, the gas phase outlet at the top of the column is connected to a reflux tank via a top condenser. A reflux pump is installed at the bottom of the reflux tank, and the condensate in the reflux tank is returned to the propylene distillation column by the reflux pump via the top reflux line.

[0009] Furthermore, a first cross-line valve is provided on the first connecting cross-line.

[0010] Furthermore, a second cross-line valve is provided on the second connecting cross-line.

[0011] Beneficial effects: This utility model's propylene distillation tower system optimization and energy-saving device optimizes and modifies the propylene distillation tower system without affecting its operation, and increases the operational flexibility of the distillation tower; it can dynamically adjust the processing capacity of the distillation tower during operation, reducing the energy consumption of the device; at the same time, it provides a reliable gas source for the dry gas sealing system of the propylene refrigeration compressor, reducing material loss during the start-up of the propylene refrigeration compressor; it eliminates the need for a high-pressure nitrogen system, saving on initial equipment investment costs, and ensuring safe and economical operation. Specifically, it includes: 1. When the unit is operating at high load, the feed position of the propylene distillation column can be flexibly switched according to the composition of the feed to ensure that the purity of the products at the top and bottom of the column meets the standards.

[0012] 2. When the concentration of light components in the feed of the propylene distillation column is low, cutting the feed to the top reflux line can save refrigerant, reflux flow, and heating, thus significantly reducing the column's operating energy consumption.

[0013] 3. Saves on losses caused by propylene entrainment in the non-condensable gas emitted during the initial startup of the propylene refrigeration compressor.

[0014] 4. No high-pressure nitrogen system is required, saving on the costs of equipment, pipelines, and land required for the original construction of the plant.

[0015] This utility model device is highly practical and easy to operate. After being put into use, it can ensure the stability of the device, reduce the difficulty of process operation, operating costs and operating risks in the production process, and has significant economic benefits. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the structure of the device for optimizing and saving energy in the propylene distillation tower system of this utility model; Among them, 1. Propylene distillation column, 2. Top condenser, 3. Reflux tank, 4. Reflux pump, 5. Reboiler, 6. Upper feed valve, 7. Middle feed valve, 8. Lower feed valve, 9. Propylene refrigeration compressor dry gas sealing system, 10. Top reflux line, 11. First cross-line valve, 12. Side line extraction valve, 13. Side line extraction line, 14. Second cross-line valve, 15. Compressor main sealing gas switching valve, 16. Compressor dry gas sealing low-pressure nitrogen line. Detailed Implementation

[0017] The technical solution of this utility model will be further described in detail below through specific embodiments. However, it should be noted that the following embodiments are only used to describe the content of the invention and do not constitute a limitation on the protection scope of this utility model.

[0018] like Figure 1 A device for optimizing and saving energy in a propylene distillation tower system includes a propylene distillation tower 1, a top condenser 2, a reflux tank 3, a reflux pump 4, a reboiler 5, an upper feed valve 6, a middle feed valve 7, a lower feed valve 8, and a dry gas sealing system for a propylene refrigeration compressor 9.

[0019] The separation process of the propylene distillation column in the original unit is as follows: propylene feed enters propylene distillation column 1 from the original feed plate in the middle of the column. The process above the feed plate is: feed → distillation column → distillation section → propylene side stream from the pasteurization section → top condenser → reflux tank → top of the column; the process below the feed plate is: feed → distillation column → stripping section → reboiler at the bottom of the column → bottom product.

[0020] Meanwhile, the main sealing gas of the dry gas sealing system of the propylene refrigeration compressor is formed by the combination of the original main sealing gas from the outlet of the propylene refrigeration compressor and high-pressure nitrogen through a three-way valve.

[0021] The device of this utility model is a modification of the original propylene distillation column, specifically including: 1) A four-way valve is installed on the feed line of propylene distillation column 1. Upper and lower feed plates are installed at the top and bottom 6-10 trays of the original feed plate of propylene distillation column 1, respectively. A feed line is drawn from the four-way valve to the upper feed plate, the original feed plate, and the lower feed plate, respectively. An upper feed valve 6, a middle feed valve 7, and a lower feed valve 8 are installed on the three feed lines, respectively. After the modification, the feed flow of propylene distillation column 1 is as follows: feed → feed crossover four-way valve → upper, middle, and lower feed lines to feed plates → distillation column.

[0022] 2) A tee is installed at the outlet of the reflux pump 4 of the propylene distillation column 1, and a first connecting cross-line is added to the side product outflow line 13 at the top of the propylene distillation column 1. A first cross-line valve 11 is installed on the first connecting cross-line, forming a switching valve with the side product outflow valve 12. The product outflow process after the modification is: reflux pump of the propylene distillation column → first cross-line → side product outflow line → product.

[0023] 3) Add a second connecting crossover line to the top gas phase outlet of propylene distillation column 1, connecting it to the main sealing gas of the dry gas sealing system of propylene refrigeration compressor, and install a second crossover valve 14.

[0024] The optimized process for purifying propylene using the aforementioned apparatus is as follows: 1) When the concentration of heavy components in the feed increases and more heavy components need to be extracted from the bottom of the tower, the feed is switched from the middle feed valve 7 to the lower feed valve 8 to ensure that the purity of the product extracted from the top side stream of the tower meets the standards.

[0025] 2) When the concentration of propylene component in the feed increases and more propylene product needs to be collected from the top side stream of the tower, the feed is switched from the middle feed valve 7 to the upper feed valve 6 to ensure that the purity of the product collected from the bottom of the tower meets the standard.

[0026] 3) When the concentration of C2 and lighter components in the feed is low and the purity of propylene in the top reflux tank 3 has reached the standard, open the first cross-line valve 11 from the top reflux line 10 to the side line production line 13 and close the side line production valve 12.

[0027] 4) When the propylene refrigeration compressor starts or stops, or when the compressor outlet pressure fluctuates during unit operation, and the compressor outlet cannot provide the main sealing gas propylene, open the second cross-line valve 14 from the top gas phase outlet of the tower to the dry gas sealing system 9 of the propylene refrigeration compressor, and close the compressor main sealing gas switching valve 15 to achieve propylene gas sealing.

[0028] Through optimization and modification of the propylene distillation tower system, the feed to the propylene distillation tower is set to three streams: top, middle, and bottom. A side stream is added at the top of the tower to increase the reflux of the liquid phase at the top. The vapor stream at the top of the tower is added to the main sealing gas stream of the dry gas seal of the propylene refrigeration compressor. This increases the operational flexibility of the unit, saves energy and reduces consumption, ensures a reliable gas supply for the dry gas seal of the compressor unit, guarantees smooth start-up and shutdown of the propylene refrigeration compressor, and maximizes the operational efficiency of the propylene distillation tower. Specifically, this includes: 1) To ensure that the product purity remains stable and meets the standards even when the propylene distillation column is running at high load, and to improve operational flexibility; 2) Reduce the energy consumption of the equipment, improve the purity of propylene products, and maximize the benefits during the operation of the equipment; 3) Improve the reliability of propylene compressor operation; 4) Reduce initial equipment investment.

Claims

1. A device for optimizing and saving energy in a propylene distillation column system, comprising a propylene distillation column, characterized in that, The propylene distillation column is equipped with upper and lower feed plates in the stripping section above the original feed plate and the rectification section below the original feed plate, respectively. The propylene feed is connected to the upper feed plate, the original feed plate, and the lower feed plate through the upper feed valve, the middle feed valve, and the lower feed valve, respectively. A first connecting cross-line is set between the reflux line at the top of the propylene distillation column and the side output line. A second connecting cross-line is added to the gas phase outlet at the top of the column, which is connected to the main sealing gas of the dry gas sealing system of the propylene refrigeration compressor.

2. The apparatus for optimizing and saving energy in a propylene distillation column system according to claim 1, characterized in that, The position of the upper feed plate differs from that of the original feed plate by 6 to 10 trays.

3. The apparatus for optimizing and saving energy in a propylene distillation tower system according to claim 1, characterized in that, The position of the lower feed plate differs from that of the original feed plate by 6 to 10 trays.

4. The apparatus for optimizing and saving energy in a propylene distillation tower system according to claim 1, characterized in that, The gas phase outlet at the top of the column is connected to a reflux tank via a top condenser. A reflux pump is installed at the bottom of the reflux tank, and the condensate in the reflux tank is returned to the propylene distillation column by the reflux pump via the top reflux line.

5. The apparatus for optimizing and saving energy in a propylene distillation tower system according to claim 1, characterized in that, A first cross-line valve is provided on the first connecting cross-line.

6. The apparatus for optimizing and saving energy in a propylene distillation tower system according to claim 1, characterized in that, A second cross-line valve is provided on the second connecting cross-line.

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