A light hydrocarbon conversion product separation system

Abstract

The utility model discloses a light hydrocarbon conversion product separation system, including absorption tower, oil gas separation tank, desorption tower, stabilizer and compressor system, compressor system import and light hydrocarbon conversion gas phase reaction product import pipeline connection, absorption tower upper portion and light hydrocarbon conversion liquid phase reaction product import pipeline connection, absorption tower top connection absorption tower top gas exhaust pipeline, absorption tower, oil gas separation tank, desorption tower, stabilizer are connected in proper order, and the liquefied gas exhaust pipeline is connected to the stabilizer top, and the stabilizer bottom pipeline is divided into two roads, one road is connected with absorption tower upper portion, and the other road connects C6+ fraction exhaust pipeline, the stabilizer upper portion connects C5 fraction exhaust pipeline. The utility model not only reduces the device construction cost and energy consumption, but also can reduce processing cost, increase liquid collection, improve aromatic recovery rate.

Description

Technical Field

[0001] This utility model belongs to the field of petrochemical or natural gas chemical industry, and relates to a light hydrocarbon conversion system, specifically, a light hydrocarbon conversion product separation system. Background Technology

[0002] my country has relatively abundant light hydrocarbon resources, mainly consisting of C4 to C7 fractions produced from refineries. C4 fractions are primarily found in liquefied petroleum gas (LPG) products from refineries, while C5 to C7 fractions are mainly found in light naphtha fractions such as topping oil and residue oil from atmospheric distillation and catalytic reforming units. These can all serve as processing feedstocks for light hydrocarbon conversion technologies. In my country, where petroleum resources are relatively scarce, using light hydrocarbon conversion technologies to transform these relatively surplus light hydrocarbon resources into high-value-added products such as BTX and propane is of significant practical importance and economic viability, thereby improving the efficiency of petrochemical enterprises. Process optimization of the equipment is particularly crucial, as it can not only reduce production costs and improve economic efficiency but also conserve resources and lower costs.

[0003] Currently, the product separation of light hydrocarbon conversion units generally adopts an absorption stabilization system, which fractionates the products according to the different boiling points of each component. Although the technology is mature, this design not only requires high construction investment, but also consumes a lot of energy, and the processing cost remains high.

[0004] CN 207243830U discloses a side-stream product extraction device for reducing energy consumption in a stabilizer tower. The device involves a collection tank located on the upper part of the inner wall of the stabilizer tower, with a side-output pipe connected to the collection tank. A solenoid valve is installed on the side-output pipe, and its end connects to a reactor pipeline. The end of the reactor pipeline connects to a propane tower reboiler, and the outlet of the propane tower reboiler connects to a cold box pipeline. The device primarily focuses on the internal structure of the stabilizer tower. By using side-stream production, it reduces the amount of top product extracted, lowers energy consumption, increases the stabilizer tower's throughput, increases the heat source for the propane tower, and lowers processing costs. The side-stream product is linked to the reaction pipeline and returned to the reaction system.

[0005] CN 218932065U discloses a side-stream extraction system for a reforming unit stabilizer tower, including a stabilizer tower, a top product extraction and reflux system, a side-stream extraction system, and a bottom circulation heating and extraction system. The extraction and reflux system includes a top air cooler, a top product heat exchanger, and a stabilizer tower reflux tank, etc. It mainly solves the problem that existing reforming processes require the addition of a depentane tower to meet process requirements, thereby reducing the construction cost of the unit and energy consumption in production. Utility Model Content

[0006] To address the issues of high investment, high energy consumption, and high processing costs in light hydrocarbon conversion plants, this utility model provides a light hydrocarbon conversion product separation system.

[0007] The light hydrocarbon conversion product separation system provided by this utility model includes an absorption tower, an oil-gas separator, a desorption tower, a stabilization tower, and a compressor system. The compressor system is equipped with an interstage cooler. The upper part of the absorption tower is connected to the inlet pipeline of the liquid phase reaction product of the light hydrocarbon conversion, and the top of the absorption tower is connected to the top gas discharge pipeline. The bottom of the absorption tower is connected to the upper part of the oil-gas separator via a pipeline, and the top of the oil-gas separator is connected to the lower part of the absorption tower via a pipeline. The upper part of the oil-gas separator is connected to the outlet of the compressor system via a pipeline, and the inlet of the compressor system is connected to the inlet pipeline of the gas phase reaction product of the light hydrocarbon conversion. The bottom of the oil-gas separator is connected to the middle part of the desorption tower via a pipeline, and the bottom of the desorption tower is connected to the middle part of the stabilization tower via a pipeline. The upper middle part of the stabilization tower is connected to the C5 fraction discharge pipeline, and the top of the stabilization tower is connected to the liquefied gas discharge pipeline. The bottom pipeline of the stabilization tower is divided into two paths, one connected to the upper part of the absorption tower and the other connected to the C6+ fraction discharge pipeline.

[0008] As an improvement, the top gas discharge pipeline of the absorption tower is connected to the inlet of the top cooler of the absorption tower, the outlet of the top cooler of the absorption tower is connected to the middle of the hydrogen-rich gas separator tank through a pipeline, the bottom of the hydrogen-rich gas separator tank is connected to the upper part of the stabilizer tower through a pipeline, and the top of the hydrogen-rich gas separator tank is connected to the hydrogen-rich gas discharge pipeline.

[0009] As another improvement, the top of the desorption tower is connected to the inlet of the compressor system interstage cooler via a pipeline.

[0010] The compressor system is configured for two to three stages of compression, compressing to 1.5–3.0 MPa (gauge pressure).

[0011] The operating pressure at the top of the absorption tower is 1.3 to 2.8 MPa (gauge pressure). The gas at the top of the tower is condensed to 0 to 10°C by the top cooler of the absorption tower and sent to the hydrogen-rich gas separator. The hydrogen-rich gas at the top of the separator is sent to the PSA unit, and the liquid phase at the bottom of the separator is sent to the stabilizer. The top cooler of the absorption tower uses chilled water or propane as the cold source.

[0012] The desorption tower operates at a pressure of 1.2–1.8 MPa (gauge pressure) at the top and at a temperature of 45–55°C at the top. The bottom operating temperature is 140–160°C. Before the gas phase at the top of the desorption tower enters the compressor interstage cooler according to the pressure matching, the liquid at the bottom of the tower is sent to the stabilizer under cascaded liquid level and flow rate.

[0013] The stabilization tower operates at a top pressure of 1.0–1.5 MPa (gauge pressure), a top temperature of 50–60°C, and a bottom temperature of 220–260°C. The bottom is heated by a reboiler or thermal oil. The liquefied petroleum gas (LPG) product from the top is sent to a gas separation unit. A side stream outlet is located in the upper section of the tower, and the tower is equipped with a sensitive plate or temperature difference control to regulate the side stream output. The C5 fraction from the side stream is returned to the reaction system as recycled material. The C6+ fraction from the bottom is partially returned to the absorption tower and partially sent to the aromatics separation unit under cascaded liquid level and flow rate control.

[0014] The workflow of this utility model is as follows:

[0015] (1) The light hydrocarbon conversion liquid phase reaction product enters the absorption tower from the top of the absorption tower as an absorbent through the light hydrocarbon conversion liquid phase reaction product inlet pipeline. The bottom flow of the absorption tower enters the oil-gas separator through the pipeline. The hydrogen-rich gas at the top of the absorption tower enters the top cooler of the absorption tower through the pipeline and is condensed and then sent to the hydrogen-rich gas separator. The hydrogen-rich gas at the top of the separator is sent to the PSA unit through the hydrogen-rich gas discharge pipeline. The liquid phase at the bottom of the separator is sent to the stabilizer tower.

[0016] (2) The gas-phase reaction products of light hydrocarbon conversion enter the compressor system through the inlet pipeline of the gas-phase reaction products of light hydrocarbon conversion. They are mixed with the top gas of the desorption tower sent from the top of the desorption tower to the interstage cooler of the compressor system and then pressurized before entering the oil-gas separator. In the oil-gas separator, they are mixed with the stream from the bottom of the absorption tower and then separated into gas and liquid. The gas at the top of the tank is sent into the absorption tower from the bottom of the absorption tower, and the liquid at the bottom of the tank is sent into the desorption tower.

[0017] (3) The top gas of the desorption tower returns from the top of the desorption tower to the interstage cooler of the compressor system, and the bottom liquid phase of the desorption tower is sent to the stabilizer.

[0018] (4) The liquefied gas product at the top of the stabilizer is sent to the gas separation unit through the liquefied gas discharge pipeline. Part of the C6+ fraction at the bottom of the stabilizer is returned to the absorption tower as a circulating absorbent, and the rest is sent to the aromatics separation unit as a product through the C6+ fraction discharge pipeline. The C5 fraction product on the side stream of the stabilizer is returned to the reaction system as a circulating material through the C5 fraction discharge pipeline.

[0019] The light hydrocarbon conversion technology in this invention mainly refers to light hydrocarbon aromatization technology. This process uses various C4-C7 light hydrocarbons, such as naphtha and / or liquefied petroleum gas, as raw materials. Through a series of complex reactions on an aromatization catalyst, including selective cracking of naphtha, olefin alkylation and cyclization dehydrogenation, and hydrogen transfer, aromatics and propane are produced, with hydrogen as a byproduct. In other words, the main components of the light hydrocarbon conversion products are aromatics, propane, and hydrogen.

[0020] This utility model has the following beneficial effects:

[0021] 1) By adding a C5 fraction discharge pipeline to the upper section of the stabilizer tower, the C5 fraction is returned to the reaction system as a circulating material, enabling the stabilizer tower to separate three products. Compared with the conventional process, one fractionation tower is reduced, which not only reduces the construction cost and energy consumption of the unit, but also reduces the processing cost.

[0022] 2) By setting up a cooler at the top of the absorption tower and a hydrogen-rich gas separator to cool and separate the gas from the gas, the aromatic content in the dry gas can be reduced. The liquid recovered at the bottom of the separator is recycled to the stabilizer, which can increase liquid recovery and improve the aromatic recovery rate.

[0023] 3) By connecting the top of the desorption tower to the inlet of the compressor system interstage cooler through a pipeline, the top gas of the desorption tower can be returned to the front of the compressor system interstage cooler according to the pressure matching, which can reduce the operating pressure of the desorption tower, reduce the equipment investment and energy consumption of the desorption tower, and improve the economic efficiency of the unit.

[0024] 4) The light hydrocarbon conversion product separation system of this utility model can be used in, but is not limited to, light hydrocarbon propane production units and light hydrocarbon aromatization units. The light hydrocarbon propane production unit uses propane as the main product and aromatics as a byproduct; while the light hydrocarbon aromatization unit uses aromatics as the main product and propane as a byproduct. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this utility model.

[0026] In the diagram: 1-Inlet pipeline for light hydrocarbon conversion gas phase reaction products, 2-Compressor system, 3-Oil-gas separator, 4-Absorber, 5-Inlet pipeline for light hydrocarbon conversion liquid phase reaction products, 6-Desorption tower, 7-Absorber top cooler, 8-Hydrogen-rich gas separator, 9-Stabilizer, 10-C5 fraction discharge pipeline, 11-Absorber top gas discharge pipeline, 12-Hydrogen-rich gas discharge pipeline, 13-Liquefied gas discharge pipeline, 14-C6+ fraction discharge pipeline. Detailed Implementation

[0027] The present invention will now be further described with reference to the accompanying drawings.

[0028] like Figure 1As shown, the light hydrocarbon conversion product separation system provided by this utility model includes an absorption tower 4, an oil-gas separator 3, a desorption tower 6, a stabilization tower 9, a compressor system 2, an absorption tower top cooler 7, and a hydrogen-rich gas separator 8. The compressor system 2 is equipped with an interstage cooler (not shown in the figure). The upper part of the absorption tower 4 is connected to the inlet pipeline 5 of the light hydrocarbon conversion liquid phase reaction product. The top of the absorption tower is connected to the absorption tower top cooler 7 through the absorption tower top gas discharge pipeline 11. The absorption tower top cooler 7 is connected to the middle of the hydrogen-rich gas separator 8 through a pipeline. The bottom of the hydrogen-rich gas separator 8 is connected to the upper part of the stabilization tower 9 through a pipeline. The top of the hydrogen-rich gas separator 8 is connected to the hydrogen-rich gas discharge pipeline 12.

[0029] The bottom of the absorption tower 4 is connected to the upper part of the oil-gas separator 3 via a pipeline, the top of the oil-gas separator 3 is connected to the lower part of the absorption tower 4 via a pipeline, the upper part of the oil-gas separator 3 is connected to the outlet of the compressor system 2 via a pipeline, and the inlet of the compressor system 2 is connected to the inlet pipeline 1 of the light hydrocarbon conversion gas phase reaction product; the bottom of the oil-gas separator 3 is connected to the middle part of the desorption tower 6 via a pipeline, the bottom of the desorption tower 6 is connected to the middle part of the stabilization tower 9 via a pipeline, and the top of the desorption tower 6 is connected to the inlet of the interstage cooler of the compressor system 2 via a pipeline.

[0030] The upper part of the stabilizer tower 9 is connected to the C5 fraction discharge pipeline 10, the top of the stabilizer tower 9 is connected to the liquefied gas discharge pipeline 13, and the bottom pipeline of the stabilizer tower 9 is divided into two lines, one of which is connected to the upper part of the absorption tower 4, and the other of which is connected to the C6+ fraction discharge pipeline 14.

[0031] The workflow of this utility model is as follows:

[0032] (1) The light hydrocarbon conversion liquid phase reaction product enters the absorption tower 4 from the top through the light hydrocarbon conversion liquid phase reaction product inlet pipeline 5 as an absorbent. The bottom stream of the absorption tower 4 enters the oil-gas separator 3 through the pipeline. The hydrogen-rich gas at the top of the absorption tower 4 enters the top cooler 7 through the top gas discharge pipeline 11 and is then sent to the hydrogen-rich gas separator 8 after condensation. The hydrogen-rich gas at the top of the separator is sent to the PSA unit through the hydrogen-rich gas discharge pipeline 12, and the liquid phase at the bottom of the separator is sent to the stabilizer tower 9.

[0033] (2) The gas-phase reaction products of light hydrocarbon conversion enter the compressor system 2 through the light hydrocarbon conversion gas-phase reaction product inlet pipeline 1. After mixing and pressurizing with the top gas of the desorption tower sent from the top of the desorption tower 6 to the interstage cooler of the compressor system 2, the mixture enters the oil-gas separator 3. In the oil-gas separator 3, the mixture is mixed with the stream from the bottom of the absorption tower 4 and then gas-liquid separation is performed. The gas at the top of the separator is sent into the absorption tower 4 from the bottom, and the liquid at the bottom of the separator is sent into the desorption tower 6.

[0034] (3) The top gas of the desorption tower 6 returns from the top of the desorption tower 6 to the interstage cooler of the compressor system 2, and the bottom liquid phase of the desorption tower 6 is sent to the stabilizer tower 9.

[0035] (4) The liquefied gas product at the top of the stabilizer tower 9 is sent to the gas separation unit through the liquefied gas discharge pipeline 13. A portion of the C6+ fraction at the bottom of the stabilizer tower 9 is returned to the absorption tower 4 as a circulating absorbent, and the remainder is sent to the aromatics separation unit as a product through the C6+ fraction discharge pipeline 14. The C5 fraction, the product from the side stream of the stabilizer tower 9, is returned to the reaction system as a circulating material through the C5 fraction discharge pipeline 10.

[0036] The above description is merely a typical embodiment of this utility model and does not impose any limitations on this utility model. Any changes or modifications made by those skilled in the art without departing from the scope of this utility model's technical solution should be considered equivalent examples of the same variations. Any equivalent changes made to the above embodiments based on the technical essence of this utility model without departing from its technical solution are within the protection scope of this utility model's technical solution.

Claims

1. A light hydrocarbon conversion product separation system, characterized in that: The system includes an absorption tower, an oil-gas separator, a desorption tower, a stabilization tower, and a compressor system. The compressor system is equipped with an interstage cooler. The upper part of the absorption tower is connected to the inlet pipeline of the light hydrocarbon conversion liquid phase reaction product. The top of the absorption tower is connected to the top gas discharge pipeline. The bottom of the absorption tower is connected to the upper part of the oil-gas separator via a pipeline. The top of the oil-gas separator is connected to the lower part of the absorption tower via a pipeline. The upper part of the oil-gas separator is connected to the outlet of the compressor system via a pipeline. The inlet of the compressor system is connected to the inlet pipeline of the light hydrocarbon conversion gas phase reaction product. The bottom of the oil-gas separator is connected to the middle part of the desorption tower via a pipeline. The bottom of the desorption tower is connected to the middle part of the stabilization tower via a pipeline. The upper middle part of the stabilization tower is connected to the C5 fraction discharge pipeline. The top of the stabilization tower is connected to the liquefied gas discharge pipeline. The bottom pipeline of the stabilization tower is divided into two branches: one branch is connected to the upper part of the absorption tower, and the other branch is connected to the C6+ fraction discharge pipeline.

2. The light hydrocarbon conversion product separation system according to claim 1, characterized in that: The top gas discharge pipeline of the absorption tower is connected to the inlet of the top cooler of the absorption tower. The outlet of the top cooler of the absorption tower is connected to the middle of the hydrogen-rich gas separator through a pipeline. The bottom of the hydrogen-rich gas separator is connected to the upper part of the stabilizer through a pipeline. The top of the hydrogen-rich gas separator is connected to the hydrogen-rich gas discharge pipeline.

3. The light hydrocarbon conversion product separation system according to claim 1, characterized in that: The top of the desorption tower is connected to the inlet of the compressor system interstage cooler via a pipeline.

4. The light hydrocarbon conversion product separation system according to claim 2, characterized in that: The top of the desorption tower is connected to the inlet of the compressor system interstage cooler via a pipeline.

5. The light hydrocarbon conversion product separation system according to any one of claims 1 to 4, characterized in that: The compressor system is configured for two to three stages of compression.

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