A coal chemical propylene refrigeration device gas propylene auxiliary recovery system

Abstract

The utility model discloses a kind of for coal chemical industry propylene refrigeration device gas propylene auxiliary recovery system, the system includes acid removal resorption tower, propylene storage tank, propylene compressor, inlet separator, series water cooler, acid removal tail gas absorption tower and multiple groups of pipelines: the-60 ℃ CO2 of acid removal resorption tower is wound propylene storage tank heat exchange by No. 1 pipeline, condensation recovery gas propylene;Propylene compressor outlet gas propylene is circulated after water cooler, inlet separator, liquid phase enters propylene storage tank, gas phase returns compressor;Normal temperature CO2 is replaced by low-pressure steam after heating and enters acid removal tail gas absorption tower by No. 2 pipeline, temperature is raised;Propylene storage tank liquid phase propylene is sent acid removal unit after economizer, and the system can improve propylene recovery rate, reduce compressor energy consumption, reduce steam consumption, improve the continuous operation stability and energy efficiency level of coal chemical plant.

Description

Technical Field

[0001] This utility model relates to the field of propylene refrigeration technology in coal chemical industry, specifically to an auxiliary propylene gas recovery system for propylene refrigeration equipment in coal chemical industry, which is applicable to the recovery and energy-saving optimization of propylene gas in propylene refrigeration systems in coal chemical processes such as coal-to-olefins and coal-to-ethylene glycol. Background Technology

[0002] In the modern coal chemical industry, core processes such as coal-to-olefins and coal-to-ethylene glycol require a precise and stable low-temperature environment within a wide temperature range of -40℃ to 10℃. The propylene refrigeration system is the core equipment for achieving this low-temperature environment.

[0003] The current propylene refrigeration technology in the coal chemical industry faces the following core problems:

[0004] Firstly, traditional multi-effect propylene refrigeration cycles have high energy density, with the unit cooling capacity power consumption of plants with an annual output of more than 1 million tons being 8%-15% higher than the industry's advanced level, which does not meet the energy-saving requirements under the "dual carbon" target.

[0005] Secondly, the coupling and adaptability between the refrigeration system and the process is poor. When the fluctuation of the raw coal type causes dynamic changes in the process cooling demand, the system adjustment response is lagging, which can easily lead to excess or insufficient cooling, resulting in a 5%-10% decrease in product separation efficiency.

[0006] Third, propylene recovery is difficult. Mainstream units rely on circulating water to cool and condense the propylene gas at the compressor outlet. However, the cooling effect of circulating water is poor during high-temperature periods, resulting in a lower propylene recovery rate. This leads to increased compressor outlet pressure and energy consumption. At the same time, it is difficult to replenish propylene externally, which seriously affects the continuous operation of the unit.

[0007] Therefore, developing a propylene refrigeration auxiliary recovery system that is adapted to coal chemical working conditions, has low energy consumption, and high recovery rate has become a key requirement for the industry to reduce costs, increase efficiency, and upgrade to a green model. Utility Model Content

[0008] This utility model aims to provide an auxiliary propylene recovery system for a propylene refrigeration unit in coal chemical industry. By reusing the -60℃ CO8 from the acid stripping reabsorption tower to exchange heat with the propylene storage tank, it achieves efficient condensation and recovery of gaseous propylene, reduces system energy consumption, solves the problem of external propylene replenishment during high-temperature periods, and eliminates the need for low-pressure steam for raising the temperature of the acid stripping tail gas absorption tower, thereby improving the continuous and stable operation capability of the unit.

[0009] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0010] This utility model discloses an auxiliary propylene recovery system for a propylene refrigeration unit in a coal chemical industry, comprising:

[0011] Acid stripping and reabsorption tower is used to remove CO2 gas at -60℃;

[0012] Pipeline No. 1 is connected at its inlet to the CO2 desorption outlet of the acid desorption and reabsorption tower.

[0013] The output end of the No. 1 pipeline extends to the outer wall of the propylene storage tank and is arranged in a winding manner on the tank wall of the propylene storage tank.

[0014] Pipeline No. 2 has its input end connected to the end of Pipeline No. 1, and its output end is connected to the upper middle inlet of the acid removal tail gas absorption tower.

[0015] A propylene compressor, the inlet of which is connected to the gas phase outlet of an inlet separator, the inlet separator being connected to pipeline number four to allow the input of gaseous propylene from acid stripping;

[0016] Two water coolers are connected in series. The outlet of the propylene compressor is connected to the inlet of the first water cooler, the outlet of the first water cooler is connected to the inlet of the second water cooler, and the outlet of the second water cooler is connected to an inlet at the top of the propylene storage tank.

[0017] Preferably, it also includes a propylene supply pipeline, the output end of which is connected to the raw material supply inlet at the top of the propylene storage tank.

[0018] Preferably, the device further includes an economizer, wherein the liquid phase outlet at the bottom of the propylene storage tank is connected to the feed inlet of the economizer, the liquid phase outlet of the economizer is connected to the conveying pipeline for the acid removal of liquid propylene, and the top outlet of the economizer is connected to the propylene compressor via pipeline No. 3.

[0019] Preferably, the bottom inlet of the acid removal tail gas absorption tower is connected to a No. 5 pipeline for inputting low-pressure steam, and the gas phase outlet of the acid removal tail gas absorption tower is connected to a venting cylinder.

[0020] Preferably, the diameter of the first pipeline is smaller than that of the second pipeline, and there are at least two first pipelines, which are wound in parallel around the tank wall of the propylene storage tank and then connected to the second pipeline.

[0021] Preferably, the gas phase outlet of the inlet separator is connected to the inlet of the propylene compressor via pipeline No. 6, forming a gas-propylene circulation loop, which is connected to pipeline No. 3.

[0022] Preferably, a No. 7 pipeline is provided between the outlet of the propylene compressor and the inlet of the first water cooler, a No. 8 pipeline is provided between the outlet of the first water cooler and the inlet of the second water cooler, and a No. 9 pipeline is provided between the outlet of the second water cooler and the top of the propylene storage tank.

[0023] Preferably, a first regulating valve is installed on the first pipeline to control the flow rate of -60℃ CO2 gas entering the propylene storage tank; a second regulating valve is installed on the second pipeline to control the flow rate of ambient temperature CO2 entering the acid removal tail gas absorption tower.

[0024] Beneficial effects: Improved propylene recovery rate: Heat exchange between -60℃ CO2 and the propylene storage tank enhances the condensation effect of gaseous propylene, increasing the propylene recovery rate during high-temperature periods; Reduced system energy consumption: After the pressure in the propylene storage tank decreases, the compressor outlet pressure drops, reducing the power consumption per unit of cooling capacity; At the same time, ambient temperature CO2 replaces low-pressure steam, eliminating the need for steam consumption in the tail gas absorption tower, thus reducing steam usage; Ensured continuous operation: The problem of difficulty in external propylene replenishment during high-temperature periods is solved, enhancing the system's resistance to operating condition fluctuations and extending the continuous operation cycle of the unit. Attached Figure Description

[0025] Figure 1 This is a block diagram of the system principle of this utility model. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Invention content / principle:

[0028] This utility model discloses an auxiliary propylene recovery system for a propylene refrigeration unit in coal chemical industry. It integrates low-temperature CO2 heat exchange, propylene circulation optimization, and tail gas temperature enhancement and reuse. The specific structure and connection relationships are as follows:

[0029] The system mainly includes an acid desulfurization reabsorption tower, a propylene storage tank, a propylene compressor, an inlet separator, two water coolers connected in series, an economizer (a tank that achieves intermediate gas replenishment, reduces compressor power consumption, and improves refrigeration efficiency through heat exchange between high-pressure liquid propylene and low-pressure propylene gas), an acid desulfurization tail gas absorption tower, and supporting pipelines such as pipeline No. 1, pipeline No. 2, pipeline No. 3, pipeline No. 4, pipeline No. 5, pipeline No. 6, pipeline No. 7, pipeline No. 8, pipeline No. 9, and propylene supply pipeline. At the same time, regulating valves are installed on key pipelines to achieve flow and temperature control.

[0030] Low-temperature CO2 transport and heat exchange loop: The CO2 desorption outlet of the acid stripping reabsorption tower is connected to the input end of pipeline No. 1. Pipeline No. 1 consists of at least two small-diameter pipelines, whose output ends extend to the outer wall of the propylene storage tank and are arranged in parallel and winding manner to ensure sufficient contact and heat exchange with the propylene inside the tank. A first regulating valve is installed on pipeline No. 1 to precisely control the transport flow rate of CO2 at -60℃. The end of pipeline No. 1 is connected to the input end of pipeline No. 2. Pipeline No. 2 is a large-diameter pipeline, whose output end is connected to the upper middle inlet of the acid stripping tail gas absorption tower. A second regulating valve is installed on pipeline No. 2 to regulate the input amount of CO2 at room temperature. Propylene compression and circulation loop: The inlet separator receives gaseous propylene from acid stripping via pipeline No. 4. The gas phase outlet of the inlet separator is connected to the inlet of the propylene compressor via pipeline No. 6. The outlet of the propylene compressor is connected to the inlet of the first water cooler via pipeline No. 7. The outlet of the first water cooler is connected to the inlet of the second water cooler via pipeline No. 8. The outlet of the second water cooler is connected to an inlet at the top of the propylene storage tank via pipeline No. 9. The liquid phase outlet at the bottom of the propylene storage tank is connected to the feed inlet of the economizer via pipeline. The liquid phase outlet of the economizer is connected to the conveying pipeline for liquid propylene to acid stripping via pipeline. The outlet at the top of the economizer is connected to the inlet of the propylene compressor via pipeline No. 3, forming a propylene recycling path. Auxiliary function pipelines: The top of the propylene storage tank is also connected to a propylene supply pipeline, the output of which corresponds to the raw material supply inlet of the propylene storage tank, used to replenish raw materials when propylene is insufficient; the bottom inlet of the acid stripping tail gas absorption tower is connected to pipeline No. 5, which is used to input low-pressure steam (as a backup heating method, which can be shut down under normal operating conditions), and the gas phase outlet of the acid stripping tail gas absorption tower is connected to the venting cylinder to achieve compliant discharge of the treated tail gas.

[0031] The system indirectly exchanges heat between -60°C low-temperature CO2 generated by the acid stripping reabsorption tower and gaseous propylene in the propylene storage tank. The low temperature of CO2 causes the gaseous propylene to condense into a liquid phase, which improves the propylene recovery rate and reduces the pressure in the propylene storage tank. The CO2, which is heated to room temperature after heat exchange, is then transported to the acid stripping tail gas absorption tower to exchange heat with the tail gas in the tower to raise the tail gas temperature, replacing the traditional low-pressure steam heating method. At the same time, the gaseous propylene at the propylene compressor outlet is cooled by a two-stage water cooler and then separated into gas and liquid phases by an inlet separator. The liquid phase propylene enters the storage tank, while the gaseous phase propylene returns to the compressor for circulation. Combined with the gas phase recovery of the economizer, a highly efficient propylene circulation process is formed, ultimately reducing system energy consumption and improving operational stability.

[0032] Example 1:

[0033] The implementation method of this system is described in detail below with reference to the accompanying drawings and the connection relationship of the components.

[0034] Low-temperature CO2 heat exchange process: -60℃ CO2 generated by the acid stripping reabsorption tower is transported to the propylene storage tank via pipeline No. 1 (at least 2 small-diameter pipelines) with a first regulating valve. Pipeline No. 1 is wound in parallel around the tank wall of the propylene storage tank to exchange heat with the propylene in the tank, so that the gaseous propylene in the tank is condensed and recovered. After heat exchange, the CO2 is heated to room temperature and sent to the middle and upper inlet of the acid stripping tail gas absorption tower via pipeline No. 2 (large-diameter pipeline) with a second regulating valve.

[0035] Propylene compression and circulation process: The propylene compressor inlet is connected to the gas phase outlet of the inlet separator via pipeline No. 6. The inlet separator receives gaseous propylene from acid stripping via pipeline No. 4. The propylene compressor outlet is connected to the first water cooler via pipeline No. 7. The outlet of the first water cooler is connected to the second water cooler via pipeline No. 8. The outlet of the second water cooler is connected to the top inlet of the propylene storage tank via pipeline No. 9. The liquid phase outlet at the bottom of the propylene storage tank is connected to the feed inlet of the economizer via pipeline. The liquid phase outlet of the economizer is connected to the conveying pipeline for liquid propylene to acid stripping via pipeline. The top outlet of the economizer is connected to the propylene compressor inlet via pipeline No. 3, forming a propylene circulation loop.

[0036] Tail gas heating process: Low-pressure steam (backup) is connected to the bottom of the acid stripping tail gas absorption tower through pipeline No. 5. After the ambient temperature CO2 transported by pipeline No. 2 enters the tower, it exchanges heat with the tail gas to achieve heating, avoids low temperature freezing blockage of tail gas, and reduces the continuous use of low-pressure steam.

[0037] Control method: The low-temperature CO2 flow rate is controlled by the first regulating valve on pipeline No. 1 to match the heat exchange requirements of the propylene storage tank; the ambient temperature CO2 flow rate is adjusted by the second regulating valve on pipeline No. 2 to maintain the outlet temperature of the tail gas absorption tower at 10℃-15℃.

[0038] Finally, it should be noted that this utility model is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this utility model should be considered within the protection scope of this utility model.

Claims

1. A propylene auxiliary recovery system for propylene refrigeration equipment in coal chemical industry, characterized in that, include: Acid stripping and reabsorption tower is used to remove CO2 gas at -60℃; Pipeline No. 1 is connected at its inlet to the CO2 desorption outlet of the acid desorption and reabsorption tower. The output end of the No. 1 pipeline extends to the outer wall of the propylene storage tank and is arranged in a winding manner on the tank wall of the propylene storage tank. Pipeline No. 2 has its input end connected to the end of Pipeline No. 1, and its output end is connected to the upper middle inlet of the acid removal tail gas absorption tower. A propylene compressor, the inlet of which is connected to the gas phase outlet of an inlet separator, the inlet separator being connected to pipeline number four to allow the input of gaseous propylene from acid stripping; Two water coolers are connected in series. The outlet of the propylene compressor is connected to the inlet of the first water cooler, the outlet of the first water cooler is connected to the inlet of the second water cooler, and the outlet of the second water cooler is connected to an inlet at the top of the propylene storage tank.

2. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, It also includes a propylene supply pipeline, the output end of which is connected to the raw material supply inlet at the top of the propylene storage tank.

3. A propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1 or 2, characterized in that, It also includes an economizer, the liquid phase outlet at the bottom of the propylene storage tank is connected to the feed inlet of the economizer, the liquid phase outlet of the economizer is connected to the conveying pipeline for liquid propylene acid removal, and the top outlet of the economizer is connected to the propylene compressor through pipeline No.

3.

4. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, The bottom inlet of the acid removal tail gas absorption tower is connected to a No. 5 pipeline for inputting low-pressure steam, and the gas phase outlet of the acid removal tail gas absorption tower is connected to a venting cylinder.

5. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, The diameter of the No. 1 pipeline is smaller than that of the No. 2 pipeline, and there are at least two No. 1 pipelines, which are wound in parallel around the tank wall of the propylene storage tank and then connected to the No. 2 pipeline.

6. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, The gas phase outlet of the inlet separator is connected to the inlet of the propylene compressor via pipeline No. 6, forming a gas propylene circulation loop, which is connected to pipeline No.

3.

7. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, Pipeline No. 7 is installed between the outlet of the propylene compressor and the inlet of the first water cooler; pipeline No. 8 is installed between the outlet of the first water cooler and the inlet of the second water cooler; and pipeline No. 9 is installed between the outlet of the second water cooler and the top of the propylene storage tank.

8. The propylene auxiliary recovery system for a propylene refrigeration unit in a coal chemical industry according to claim 1, characterized in that, A first regulating valve is installed on the first pipeline to control the flow rate of -60℃ CO2 gas entering the propylene storage tank; a second regulating valve is installed on the second pipeline to control the flow rate of ambient temperature CO2 entering the acid removal tail gas absorption tower.

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