Tower kettle flash evaporation type propylene heat pump rectification energy-saving device
The propylene heat pump distillation unit with a tower bottom flash evaporation process solves the problem of energy waste in the propylene-propane separation process, realizes energy recycling and energy saving, and reduces the consumption of steam and circulating water.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-10
AI Technical Summary
In the existing technology, the energy grade mismatch is serious in the propylene-propane separation process, resulting in high steam consumption, and high energy consumption in the top condenser and bottom reboiler, which leads to energy waste.
A tower-bottom flash propylene heat pump distillation unit is adopted. Through the synergistic action of the compressor, evaporator and condenser, the low-temperature latent heat of the top vapor is recovered and raised to the high-temperature heat required for the bottom of the tower, thereby reducing the input of external energy.
This reduces the steam consumption in the bottom of the column, recovers the heat from the propylene at the top of the column, and reduces the amount of circulating water used at the top of the column, thus achieving energy recycling and energy saving.
Smart Images
Figure CN121623355A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical technology, and in particular relates to an energy-saving device for propylene heat pump distillation using a tower bottom flash evaporation method. Background Technology
[0002] Steam energy consumption is one of the main costs and indirect carbon emission sources for petrochemical enterprises. Therefore, reducing steam consumption has become an urgent strategic need and a direction for technological innovation in the industry. Propylene-propane separation is one of the core separation processes for obtaining high purity. Due to the extremely low relative volatility of propylene and propane (close to 1), it requires a very high reflux ratio and a large number of trays. This results in a huge amount of steam consumption in the reboiler of the propylene distillation column. In traditional processes, the top condensation requires a large amount of refrigerant to remove high-temperature heat, while the bottom reboiler requires steam injection of the same calorific value, resulting in serious energy mismatch and waste.
[0003] Heat pump distillation, as an emerging energy-saving technology, has received widespread attention in the field of chemical separation in recent years. It is an energy-saving technology that recovers the latent heat of low-temperature vapor at the top of the distillation column through a heat pump system, providing heat to the bottom of the column. Its working principle is to use the heat pump system to raise the latent heat of the vapor at the top of the column to the high-temperature heat required for the bottom, thereby achieving energy recycling. The core of this technology lies in the synergistic action of the compressor, evaporator, and condenser to transfer energy from a low-temperature heat source to a high-temperature heat source, reducing the input of external energy. Summary of the Invention
[0004] The purpose of this invention is to address the above-mentioned problems by providing an energy-saving device for propylene heat pump distillation using a tower bottom flash evaporation method.
[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A tower-type flash propylene heat pump distillation energy-saving device includes a crude propylene tower, the top of which is connected to the lower part of a refined propylene tower. The reboiler of the refined propylene tower is connected to the upper part of the crude propylene tower via an intermediate pump. The top of the refined propylene tower is connected to a steam generator, which is then connected to an auxiliary condenser. The auxiliary condenser is connected to a reflux tank, which is connected to a reflux pump. The reflux pump outlet is split into two paths: one path connects to the upper part of the refined propylene tower, and the other path is used to collect the propylene product. The crude propylene tower reboiler is connected to a flash tank via a pressure reducing valve. The vapor outlet of the flash tank is connected to a compressor and then to the lower part of the crude propylene tower. The liquid outlet of the flash tank is connected to a circulating pump, which is then connected to the compressor via a steam generator. The bottom of the refined propylene tower is connected to the upper part of the crude propylene tower via an intermediate pump, and the middle part of the crude propylene tower is connected to the feed pipe.
[0006] In the above-mentioned tower-bottom flash propylene heat pump distillation energy-saving device, a reboiler is also provided at the bottom of the crude propylene tower.
[0007] In the above-mentioned tower-bottom flash propylene heat pump distillation energy-saving device, the crude propylene tower bottom is also connected to a cooler.
[0008] In the above-mentioned tower-boiler flash propylene heat pump distillation energy-saving device, the connection between the compressor and the crude propylene tower is located above the connection between the reboiler and the crude propylene tower, the connection between the feed pipe and the crude propylene tower is located above the connection between the compressor and the crude propylene tower, and the connection between the intermediate pump and the crude propylene tower is located above the connection between the feed pipe and the crude propylene tower.
[0009] Compared with existing technologies, the advantages of this invention are: 1. This invention can reduce the consumption of steam in the tower bottom.
[0010] 2. A large amount of heat from the propylene at the top of the tower was recovered, while the amount of circulating water used at the top of the tower was reduced. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the existing technology. Detailed Implementation
[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0013] like Figure 1 As shown, a reboiler flash propylene heat pump distillation energy-saving device includes a crude propylene column S1. The top of the crude propylene column S1 is connected to the lower part of a refined propylene column S2. The reboiler of the refined propylene column S2 is connected to the upper part of the crude propylene column S1 via an intermediate pump S7. The top of the refined propylene column S2 is connected to a steam generator S12, which is then connected to an auxiliary condenser S13. The auxiliary condenser S13 is connected to a reflux tank S5. The reflux tank S5 is connected to a reflux pump S6. The outlet of the reflux pump S6 is split into two paths: one path connects to the upper part of the refined propylene column S2, and the other path is used to collect propylene product. Here, both the crude propylene column S1 and the refined propylene column S2 are existing distillation columns. The bottom of the crude propylene tower S1 is connected to flash tank 10 via pressure reducing valve S9. The vapor outlet of flash tank 10 is connected to compressor S14 and then to the lower part of crude propylene tower S1. The liquid outlet of flash tank 10 is connected to circulating pump S11. Circulating pump S11 is connected to compressor S14 via steam generator S12. The bottom of the refined propylene tower S2 is connected to the upper part of the crude propylene tower S1 via an intermediate pump S7, and the middle part of the crude propylene tower S1 is connected to the feed pipe 100.
[0014] The working principle of this invention is as follows: The top steam pipeline G1 of the propylene refiner S2 is connected to the steam generator S12. The gas at the top of the propylene refiner S2 enters the auxiliary condenser S13 after heat exchange in the steam generator S12. After condensation, it enters the reflux tank S5. After being pressurized by the reflux pump S6, it is divided into two parts. One part flows back to the top of the propylene refiner S2, and the other part is collected as propylene product. The bottom pipeline G4 of the crude propylene refiner S1 enters the flash tank S10 after being depressurized by the pressure reducing valve S9. The gas generated in the flash tank S10 enters the compressor S14. The liquid is pressurized by the circulating pump S11 and enters the steam generator S12, where it exchanges heat with the gas from the steam pipeline G1. The gas generated after heat exchange enters the compressor S14 and is compressed by the compressor S14 before returning to the bottom of the crude propylene refiner S1.
[0015] In a preferred embodiment, a reboiler S3 is also provided at the bottom of the crude propylene tower S1. The bottom of the crude propylene tower S1 is also connected to a cooler S8, from which propane cooled by the cooler S8 is collected. The connection point between the compressor S14 and the crude propylene tower S1 is located above the connection point between the reboiler S3 and the crude propylene tower S1. The connection point between the feed pipe 100 and the crude propylene tower S1 is located above the connection point between the compressor S14 and the crude propylene tower S1. The connection point between the intermediate pump S7 and the crude propylene tower S1 is located above the connection point between the feed pipe 100 and the crude propylene tower S1.
[0016] Application Example 1 Taking a 4.457 t / h crude propylene processing unit as an example, its composition is 78.73% (wt) propylene, 20.97% (wt) propane, 0.05% (wt) isobutylene, and 0.25% (wt) isobutane. The temperature of the top outlet line G1 of the propylene refining tower S2 is approximately 46.4℃, the pressure is 1.8 MPaG, and the molar vapor fraction is 1. The temperature of the outlet line G2 of the steam generator S12 is approximately 46.4℃, the pressure is 1.8 MPaG, and the molar vapor fraction is approximately 0.1. The heat load of the steam generator S12 is approximately 4.198 Gcal / h. The temperature of the outlet line G3 of the auxiliary condenser S13 is approximately 46.4℃, the pressure is 1.8 MPaG, the molar vapor fraction is approximately 0, and the heat load of the auxiliary condenser S13 is approximately 0.4717 Gcal / h. The temperature of the outlet line G4 of the crude propylene tower S1 is approximately 60.18℃, the pressure is 2.03 MPaG, and the molar vapor fraction is approximately 0. The temperature of the outlet line G5 of the pressure reducing valve S9 is approximately 30.93℃, the pressure is 1 MPaG, and the molar vapor fraction is approximately 0.2832. The temperature of the outlet line G9 of the flash tank S10 is approximately 30.93℃, the pressure is 1 MPaG, and the molar vapor fraction is approximately 1. The temperature of the outlet line G6 of the flash tank S10 is approximately 30.93℃, the pressure is 1 MPaG, and the molar vapor fraction is approximately 0.2832. The temperature of the outlet line G7 of circulating pump S11 is approximately 31℃, the pressure is 1.3 MPaG, and the molar vapor fraction is approximately 0. The temperature of the outlet line G8 of steam generator S12 is approximately 31.23℃, the pressure is 1 MPaG, and the molar vapor fraction is approximately 1. The temperature of the outlet line G10 of compressor S14 is approximately 68.9℃, the pressure is 2.03 MPaG, and the molar vapor fraction is approximately 1. The power of compressor S14 is approximately 878.6 kW. The steam consumption in the tower bottom is 0.1 t / h, and the circulating cooling water consumption is approximately 78.8 t / h.
[0017] Comparative Example 1 Referring to the structure of Example 1 and the method of Application Example 1, the pressure reducing valve S9, flash tank S10, circulating pump S11, steam generator S12, auxiliary condenser S13, and compressor S14 are removed. The top pipeline G1 of the propylene refiner S2 is connected to the condenser S4. The load of the condenser S4 is approximately 4.6697 Gcal / h, and the circulating cooling water consumption is approximately 780.1 t / h, an increase of 701.3 t / h, which is approximately 890% compared to Example 1. The bottom pipeline G4 of the crude propylene refiner S1 is connected to the reboiler S3. The load of the reboiler S3 is approximately 4.59 Gcal / h, and the bottom steam consumption is approximately 8.86 t / h, an increase of 8.85 t / h, which is approximately 8850% compared to Example 1.
[0018] The specific embodiments described herein are merely illustrative examples of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention.
Claims
1. A tower kettle flash distillation type propylene heat pump rectification energy saving device, comprising a crude propylene column (S1), characterized in that, The crude propylene column (S1) is connected to the lower part of the refined propylene column (S2), the refined propylene column (S2) is connected to the upper part of the crude propylene column (S1) through an intermediate pump (S7), the top of the refined propylene column (S2) is connected to a steam generator (S12) and then to an auxiliary condenser (S13), the auxiliary condenser (S13) is connected to a reflux tank (S5), the reflux tank (S5) is connected to a reflux pump (S6), the outlet of the reflux pump (S6) is divided into two paths, one path is connected to the upper part of the refined propylene column (S2), and the other path is used as a propylene product, The crude propylene column (S1) is connected to the lower part of the refined propylene column (S2), the refined propylene column (S2) is connected to the upper part of the crude propylene column (S1) through an intermediate pump (S7), the top of the refined propylene column (S2) is connected to a steam generator (S12) and then to an auxiliary condenser (S13), the auxiliary condenser (S13) is connected to a reflux tank (S5), the reflux tank (S5) is connected to a reflux pump (S6), the outlet of the reflux pump (S6) is divided into two paths, one path is connected to the upper part of the refined propylene column (S2), and the other path is used as a propylene product, The refined propylene column (S2) is connected to the upper part of the crude propylene column (S1) through an intermediate pump (S7), and the crude propylene column (S1) is connected to a feed pipe (100).
2. The tower kettle flash evaporation type propylene heat pump rectifying energy saving device according to claim 1, characterized in that, The lower part of the crude propylene column (S1) is also provided with a reboiler (S3).
3. The tower kettle flash evaporation type propylene heat pump rectifying energy saving device according to claim 1, characterized in that, The crude propylene column (S1) is also connected to a cooler (S8).
4. The tower kettle flash evaporation type propylene heat pump rectifying energy saving device according to claim 1, characterized in that, The connection between the compressor (S14) and the crude propylene column (S1) is located above the connection between the reboiler (S3) and the crude propylene column (S1), the connection between the feed pipe (100) and the crude propylene column (S1) is located above the connection between the compressor (S14) and the crude propylene column (S1), and the connection between the intermediate pump (S7) and the crude propylene column (S1) is located above the connection between the feed pipe (100) and the crude propylene column (S1).