Propane feed pressure stabilizing system for dehydrogenation of alkanes to olefins

Abstract

This utility model belongs to the technical field of process systems for alkane dehydrogenation, specifically relating to a propane feedstock pressure stabilization system for alkane dehydrogenation to olefins. The propane feedstock pressure stabilization system for alkane dehydrogenation to olefins described in this utility model includes a propane feed tank, a propane evaporator, and a propane transfer pump cooler connected sequentially by pipelines. The propane feed tank is connected to a propane feedstock inlet pipeline from the tank farm, a nitrogen purging pipeline, a safety valve venting pipeline, and a propane feedstock outlet pipeline. The propane evaporator is connected to the propane feedstock inlet pipeline from the tank farm via a shell-side inlet pipeline, and to the propane feed tank via a shell-side outlet pipeline. The propane transfer pump cooler is connected to the propane feed tank via a propane feedstock return pipeline. The propane feedstock pressure stabilization system for alkane dehydrogenation to olefins provided by this utility model can effectively suppress pressure fluctuations of the propane feedstock from the tank farm, enabling the reaction unit to operate safely and stably for extended periods.

Description

Technical Field

[0001] This utility model belongs to the technical field of process systems for alkane dehydrogenation, specifically relating to a propane feedstock stabilization system for alkane dehydrogenation to olefins. Background Technology

[0002] Alkane dehydrogenation is an important process route for olefin production, with propane dehydrogenation to propylene technology being particularly widely used. In this process, propane, after being pumped from the tank farm, undergoes pretreatment to remove impurities such as nitrogen oxides and moisture. It is then vaporized, heated, and finally enters the dehydrogenation reactor for the dehydrogenation reaction. The reaction products are then separated and purified to obtain high-purity propylene.

[0003] Propane feedstock is typically stored in ambient-temperature spherical tanks in the tank farm. Under storage conditions, the propane inside the spherical tank is in a state of vapor-liquid equilibrium, and its internal pressure is equal to the saturated vapor pressure of propane at the current ambient temperature. Due to seasonal changes and significant variations in ambient temperature, the operating pressure of the propane inside the tank fluctuates drastically.

[0004] In existing alkane dehydrogenation processes, reactor operating pressure is a critical parameter. Studies have shown that dehydrogenation of both low-carbon alkanes (such as propane) and long-chain alkanes (such as C10-C20) tends to proceed at lower pressures, typically controlled within the range of 0.05 MPa to 0.5 MPa. This is because the dehydrogenation reaction is a reversible reaction involving volume increase; lowering the pressure shifts the reaction equilibrium towards the formation of the target olefin, thereby increasing the conversion rate. Therefore, maintaining a suitable and stable low-pressure environment is essential for ensuring the efficient operation of the entire plant.

[0005] However, the propane feedstock from the tank farm currently experiences severe pressure fluctuations of up to approximately 0.9 MPa, creating a sharp conflict with the stable low-pressure environment required by downstream reaction units. This wide-ranging feed pressure fluctuation poses a significant challenge to subsequent process flows. Downstream pretreatment units, gasification equipment, reactor feed systems, and related instrumentation, valves, and pipelines are all designed and selected according to specific design pressures and operating conditions. Severe pressure fluctuations can induce fatigue stress in equipment and pipelines, causing control valves, flow meters, and other instruments to deviate from their optimal operating range, affecting measurement accuracy and control stability. Over the long term, this will significantly shorten the service life of equipment, instrumentation, and pipelines, increasing the risk of unplanned shutdowns and maintenance costs. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the above-mentioned defects in the existing technology and provide a propane feedstock stabilization system for alkane dehydrogenation to olefins, which can effectively suppress the pressure fluctuation of the feedstock propane from the tank area, so as to enable the reaction device to operate safely and stably for a long period of time.

[0007] The propane feedstock stabilization system for alkane dehydrogenation to olefins described in this utility model includes a propane feed tank, a propane evaporator, and a propane delivery pump cooler connected in sequence by pipelines. The propane feed tank is connected to a propane feed pipeline from the tank area, a nitrogen purging pipeline, a safety valve relief pipeline, and a propane feed outlet pipeline; The propane evaporator is connected to the propane feed line from the tank area via the shell-side inlet pipe, and the shell-side outlet pipe is connected to the propane feed tank. The propane transfer pump cooler is connected to the propane feed tank via the propane feed return pipeline, and the propane transfer pump cooler is connected to the propane feed output pipeline via the cooler shell-side feed pipeline.

[0008] The tube side of the propane evaporator is equipped with a low-pressure steam inlet pipe and a low-pressure condensate outlet pipe.

[0009] A level control valve is installed on the propane feed pipeline from the tank area, and a level gauge is installed on the propane feed tank. The level control valve is connected to the level gauge.

[0010] The propane feedstock outlet pipeline is connected to the inlet of the propane transfer pump, and the outlet pipeline of the propane transfer pump is the propane feedstock output pipeline.

[0011] A pressure regulating valve is installed on the shell-side inlet pipeline, and a remote pressure gauge is installed on the propane feed tank. The remote pressure gauge is connected to the pressure regulating valve.

[0012] A remote flow meter and a flow regulating valve are installed on the feed pipe of the cooler shell side.

[0013] The propane transfer pump cooler is equipped with a circulating water inlet pipe and a circulating water outlet pipe.

[0014] Compared with the prior art, the beneficial effects of this utility model are: This invention relates to a propane feedstock stabilization system for alkane dehydrogenation to olefins. By vaporizing a portion of the propane feedstock and adding it to the propane feed tank, and by cooling and refluxing the propane, the system bidirectionally regulates the gas phase pressure within the tank. This allows for precise stabilization of the propane feed tank's operating pressure at a predetermined 1.8 MPaG, completely eliminating pressure fluctuations from upstream tanks. A closed-loop control system consisting of a pressure regulating valve and a remote pressure gauge enables automatic adjustment under low-pressure conditions. The level control system also provides automatic feedstock replenishment, ensuring stable and reliable system operation. This system provides constant-pressure feedstock to downstream process units, effectively preventing pressure fluctuations from impacting equipment, instruments, and pipelines, extending their service life, and improving the overall operational flexibility and safety of the unit. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the propane feedstock stabilization system for alkane dehydrogenation to olefins according to this invention.

[0016] In the diagram: 1. Propane feed tank; 101. Propane feed pipeline from the tank area; 102. Nitrogen purging pipeline; 103. Safety valve relief pipeline; 104. Propane feed outlet pipeline; 105. Level gauge; 106. Level regulating valve; 2. Propane evaporator; 201. Shell-side inlet pipe; 202. Shell-side outlet pipe; 203. Low-pressure steam inlet pipe; 204. Low-pressure condensate outlet pipe; 205. Remote pressure gauge; 206. Pressure regulating valve; 3. Propane transfer pump cooler; 301. Cooler shell-side feed line; 302. Propane feed return line; 303. Circulating water inlet line; 304. Circulating water outlet line; 305. Remote flow meter; 306. Flow regulating valve; 4. Propane transfer pump; 401. Propane feedstock output pipeline. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments.

[0018] like Figure 1 As shown, the present invention provides a propane feedstock stabilization system for alkane dehydrogenation to olefins, the core equipment of which includes a propane feed tank 1, a propane evaporator 2, and a propane transfer pump cooler 3.

[0019] Propane feedstock from the tank farm enters the system via propane feedstock inlet pipe 101. This pipe is divided into two paths: one directly enters the liquid phase space of propane feed tank 1; the other enters the shell side of propane evaporator 2 via shell-side inlet pipe 201. Low-pressure steam from low-pressure steam inlet pipe 203 is introduced into the tube side of propane evaporator 2 to heat the liquid propane in the shell side and vaporize it. A low-pressure condensate outlet pipe 204 is also provided. The vaporized propane vapor is sent into the gas phase space of propane feed tank 1 via shell-side outlet pipe 202.

[0020] A remote pressure gauge 205 is installed on the propane feed tank 1 to monitor the tank pressure in real time. When the remote pressure gauge 205 detects that the tank pressure is lower than the set value, it sends a signal to the pressure regulating valve 206 installed on the shell-side inlet pipe 201, causing it to open wider and increase the propane flow into the propane evaporator 2, thereby generating more vapor to replenish the tank and raise the pressure back to the set value. Conversely, the pressure regulating valve 206 closes when the pressure is higher than the set value. This closed-loop control achieves automatic pressure stabilization.

[0021] The liquid level in propane feed tank 1 is monitored by a level gauge 105. The level gauge 105 is connected to a level regulating valve 106 installed on the propane feed pipeline 101 in the tank area, forming a level control loop. When the liquid level is low, the level regulating valve 106 is opened wider to increase the total feed; when the liquid level is high, the level regulating valve 106 is closed to maintain a stable liquid level in the tank.

[0022] Stable liquid propane flows out from propane feedstock outlet pipeline 104, is pressurized by propane transfer pump 4, and then transported to downstream units through propane feedstock output pipeline 401. At the outlet of propane transfer pump 4, a stream of propane is drawn through cooler shell-side feed pipeline 301 into the shell side of propane transfer pump cooler 3. This pipeline is equipped with a remote flow meter 305 and a flow regulating valve 306 for monitoring and regulating the return flow.

[0023] The tubes of the propane transfer pump cooler 3 are supplied with circulating cooling water from the circulating water inlet pipe 303. When the pressure inside the propane feed tank 1 exceeds the set value, the operator can manually turn on the circulating water and adjust the flow regulating valve 306. A circulating water outlet pipe is also provided. The high-pressure liquid propane returning is cooled in the cooler, its temperature decreases, and then it returns to the propane feed tank 1 through the propane feedstock return pipe 302. This portion of low-temperature propane mixes with the material inside the tank, lowering the overall temperature and reducing the saturated vapor pressure of propane in the gas phase space inside the tank, thereby effectively reducing and stabilizing the pressure inside the tank.

[0024] In addition, the propane feed tank 1 is also connected to a nitrogen purging pipeline 102 for replacement during maintenance and a safety valve relief pipeline 103 to ensure overpressure safety.

[0025] The working process of this utility model is as follows: After the propane feedstock, whose pressure fluctuates from the tank farm, enters this system, the liquid level in the propane feed tank 1 is maintained stable through the liquid level regulating valve 106 and the liquid level gauge 105 loop. When the pressure is too low, propane vapor is automatically added to increase the pressure through the pressure regulating valve 206 and the remote pressure gauge 205 loop. When the pressure is too high, manual (or automatic) intervention is performed through the propane transfer pump cooler 3 and the flow regulating valve 306 loop to cool and reduce the pressure of the reflux liquid. Finally, the propane feedstock, with a stable pressure of 1.8 MPaG, is delivered downstream by the propane transfer pump 4, thus perfectly solving the problem of raw material pressure fluctuations caused by seasonal changes.

Claims

1. A propane feed pressure stabilizing system for dehydrogenation of an alkane to an alkene, characterized by: It includes a propane feed tank (1), a propane evaporator (2), and a propane transfer pump cooler (3) connected in sequence by pipelines. The propane feed tank (1) is connected to a propane feed pipeline (101) from the tank area, a nitrogen purging pipeline (102), a safety valve discharge pipeline (103), and a propane feed outlet pipeline (104). The propane evaporator (2) is connected to the propane feed line (101) from the tank area via the shell-side inlet pipe (201), and the shell-side outlet pipe (202) is connected to the propane feed tank (1); The propane transfer pump cooler (3) is connected to the propane feed tank (1) through the propane feed return pipeline (302), and the propane transfer pump cooler (3) is connected to the propane feed output pipeline (401) through the cooler shell side feed pipeline (301).

2. The propane feed pressure stabilizing system for dehydrogenation of alkanes to olefins according to claim 1, characterized in that: The tube side of the propane evaporator (2) is equipped with a low-pressure steam inlet pipe (203) and a low-pressure condensate outlet pipe (204).

3. The propane feed pressure stabilizing system for dehydrogenation of alkanes to olefins according to claim 1, characterized in that: A level regulating valve (106) is installed on the propane feed pipeline (101) in the tank area, and a level gauge (105) is installed on the propane feed tank (1).

4. The propane feed pressure stabilizing system for dehydrogenation of alkane to olefin according to claim 1, characterized in that: The propane feedstock outlet pipeline (104) is connected to the inlet of the propane transfer pump (4), and the outlet pipeline of the propane transfer pump (4) is the propane feedstock output pipeline (401).

5. The propane feed pressure stabilizing system for dehydrogenation of alkane to olefin according to claim 1, characterized in that: A pressure regulating valve (206) is installed on the shell-side inlet pipe (201), and a remote pressure gauge (205) is installed on the propane feed tank (1). The remote pressure gauge (205) is connected to the pressure regulating valve (206).

6. The propane feed pressure stabilizing system for dehydrogenation of alkane to olefin according to claim 1, characterized in that: A remote flow meter (305) and a flow regulating valve (306) are installed on the feed line (301) of the cooler shell side.

7. The propane feedstock pressure stabilizing system for dehydrogenating alkanes to olefins according to claim 1, characterized in that: The propane transfer pump cooler (3) is equipped with a circulating water inlet pipe (303) and a circulating water outlet pipe (304).

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