Device for reducing coking of reboiler of low-pressure depropanizing tower
By using thermal water as the heat source in the low-pressure depropanizer, the problem of coking in the depropanizer is solved, and the effects of reducing energy consumption and carbon dioxide emissions are achieved.
Patent Information
- Application Number
- CN202422501736.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-10-16
AI Technical Summary
The existing depropanizer has a coking problem, and the existing method for preventing coking in the low-pressure depropanizer has safety hazards and high energy consumption.
Using heat medium water instead of steam as the heat source for the low-pressure depropanizer reboiler, by recovering waste heat from the ethylene plant or refinery, the reboiler temperature is lowered and the risk of coking is reduced.
The temperature difference of the reboiler is reduced, coking is reduced, the operation cycle is extended, and the energy consumption and carbon dioxide emissions of the entire plant are reduced.
Smart Images
Figure CN223324057U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of depropanizers, in particular to a device for reducing coking of a reboiler of a low-pressure depropanizer. Background Art
[0002] The depropanizer system is designed to prevent C4+ heavy components in the cracked gas from entering the unit's cold separation system. Depropanizers utilize a dual-tower process, operating at different pressures. The first depropanizer (high-pressure depropanizer) operates at 1.35 MPa, with sufficient C3 fraction at the bottom to maintain a moderate temperature. The bottoms from the high-pressure depropanizer enter the low-pressure depropanizer, operating at a lower pressure (0.7 MPa).
[0003] However, most of the existing depropanizers have shortcomings. Currently, the main method to prevent coking in low-pressure depropanizers is to add high-efficiency inhibitors or increase the amount of inhibitors added to delay coking. At the same time, the spare reboiler is switched to perform decoking operations. However, frequent switching, on the one hand, poses a huge safety hazard. On the other hand, decoking will damage the reboiler and increase the consumption of heating steam. Summary of the Invention
[0004] The purpose of the utility model is to provide a device for reducing coking in a reboiler of a low-pressure depropanizer, so as to solve the problems raised in the above-mentioned background technology.
[0005] To achieve the above object, the utility model provides the following technical solutions: an energy-saving device for reducing coking of a reboiler of a low-pressure depropanizer, comprising a low-pressure depropanizer, a condensate stripping tower provided on the low-pressure depropanizer, a deethanizer provided above the condensate stripping tower, a plurality of reboilers connected in series are connected to the low-pressure depropanizer, and a cutting tower is connected to the side of the reboiler close to the low-pressure depropanizer, a reflux tank is connected at one end of the plurality of reboilers connected in series away from the low-pressure depropanizer, a reflux pump and a feed pump are respectively connected on one side of the reflux tank, and the feed pump is connected to the feed pump. A high-pressure depropanizer is connected, one end of the reflux pump away from the reflux tank is connected to the low-pressure depropanizer, and the connection between the reflux pump and the low-pressure depropanizer is connected to an inlet and outlet heat exchanger, a side of the low-pressure depropanizer is connected to a reboiler, the upper and lower ends of the reboiler are respectively connected to the side and bottom of the low-pressure depropanizer, and one side of the reboiler is connected to a hot water tank, the bottom of the hot water tank is connected to a hot water circulation pump, the hot water circulation pump is connected to a heat extraction device, and the hot water circulation pump cooperates with the hot water tank and the heat extraction device to provide the reboiler with the heat source required for tower reboilering.
[0006] As a preferred embodiment of the present invention, a debutanizer is connected to the bottom of the low-pressure depropanizer to separate butane.
[0007] As a preferred embodiment of the present invention, the bottom of the low-pressure depropanizer is connected to the reboiler, the upper end of the reboiler is connected to the side of the low-pressure depropanizer, and the two sides of the reboiler are respectively connected to the low-pressure steam pipe network and the steam condensate tank, and the low-pressure steam pipe network is used to provide low-pressure steam.
[0008] As a preferred embodiment of the present invention, the heat extraction device is connected to the reboiler for transporting heat medium water.
[0009] As a preferred embodiment of the present invention, a water filling port is provided on one side of the hot water tank, and a nitrogen port is provided on the side of the hot water tank away from the water filling port for filling nitrogen, and the water filling port is used to fill water, except for salt water.
[0010] Compared with the prior art, the beneficial effects of the present invention are:
[0011] The utility model adopts heat medium water instead of steam as the heat source of the reboiler, thereby reducing the tube wall temperature of the reboiler, thereby reducing the temperature difference with the tower bottom material, reducing the occurrence of butadiene polymerization caused by temperature, extending the operation cycle, and thus alleviating the polymerization and coking phenomenon of the reboiler.
[0012] The heat source of the heat medium water can be the waste heat inside the ethylene cracking unit, the waste heat from the refinery or the waste heat from the aromatics unit, or other waste heat such as the process condensate of the entire plant.
[0013] Since the tower's reboiler is changed from steam to circulating heat medium water, steam is used as the heat source instead of steam, which reduces the tower's steam consumption, and reduces the energy consumption of the entire plant and the carbon dioxide emissions of the entire plant. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a schematic diagram of the structure of the utility model low-pressure depropanizer using 0.4MpaA steam reboiler design;
[0015] Figure 2 This is a schematic diagram of the structure of the low-pressure depropanizer designed with heat medium water reboiling in the utility model.
[0016] In the figure: 1. Low-pressure depropanizer; 2. Deethanizer; 3. Condensate stripping tower; 4. Low-pressure steam network; 5. Steam condensate tank; 6. Debutanizer; 7. Inlet and outlet heat exchanger; 8. Reflux pump; 9. Feed pump; 10. High-pressure depropanizer; 11. Reflux tank; 12. Cutting tower; 13. Hot water tank; 14. Heat extraction device; 15. Hot water pump; 16. Nitrogen inlet; 17. Water inlet; 18. Reboiler. DETAILED DESCRIPTION
[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0018] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.
[0019] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in this utility model based on specific circumstances.
[0020] See also Figure 1-2 The utility model provides a technical solution: an energy-saving device for reducing coking of a low-pressure depropanizer reboiler, characterized in that: it includes a low-pressure depropanizer 1, a condensate stripping tower 3 is provided on the low-pressure depropanizer 1, a deethanizer 2 is provided above the condensate stripping tower 3, a plurality of reboilers 18 connected in series are connected to the low-pressure depropanizer 1, and a cutting tower 12 is connected to the side of the reboiler 18 close to the low-pressure depropanizer 1, a reflux tank 11 is connected to one end of the plurality of reboilers 18 away from the low-pressure depropanizer 1, a reflux pump 8 and a feed pump 9 are connected to one side of the reflux tank 11, and the feed pump 9 is connected to A high-pressure depropanizer 10, the reflux pump 8 is connected to the low-pressure depropanizer 1 at one end away from the reflux tank 11, and the connection between the reflux pump 8 and the low-pressure depropanizer 1 is connected to the feed and discharge heat exchanger 7, the side of the low-pressure depropanizer 1 is connected to a reboiler 18, the upper and lower ends of the reboiler 18 are respectively connected to the side and bottom of the low-pressure depropanizer 1, and one side of the reboiler 18 is connected to a hot water tank 13, the bottom of the hot water tank 13 is connected to a hot water circulation pump 15, the hot water circulation pump 15 is connected to a heat extraction device 14, and the hot water pump 15 cooperates with the hot water tank 13 and the heat extraction device 14 to provide hot water for the reboiler 18.
[0021] Furthermore, a debutanizer 6 is connected to the bottom of the low-pressure depropanizer 1 for separating butane.
[0022] Furthermore, the bottom of the low-pressure depropanizer 1 is connected to the reboiler 18, the upper end of the reboiler 18 is connected to the side of the low-pressure depropanizer 1, and the two sides of the reboiler 18 are respectively connected to the low-pressure steam pipe network 4 and the steam condensate tank 5, and the low-pressure steam pipe network 4 is used to provide low-pressure steam.
[0023] Furthermore, the heat extraction device 14 is connected to the reboiler 18 for transporting heat medium water.
[0024] Furthermore, a water supply port 17 is provided on one side of the hot water tank 13, and a nitrogen port 16 is provided on the side of the hot water tank 13 away from the water supply port 17 for filling nitrogen. The water supply port 17 is used to supply water, except for salt water.
[0025] Working principle: This device adds a water heat medium system to extract the waste heat from the ethylene plant, refinery, aromatics plant or condensate through the water heat medium, and sends it to the reboiler 18 of the low-pressure depropanizer 1 as a heat source. The hot water stored in the hot water tank 13 is pumped into the heat extraction device 14 through a circulating water pump to exchange heat with various waste heat. The hot water after heat exchange enters the reboiler 18 through a pipeline and serves as the heat source of the reboiler. According to the water volume of the heat medium system, the hot water tank 13 can be replenished with water through the water replenishment port 17 set on the side of the hot water tank 13. The nitrogen port 16 set on the side of the hot water tank 13 away from the water replenishment port 17 is used to add nitrogen. Nitrogen can form an inert atmosphere. The main function of nitrogen is to isolate oxygen in the environment, which is used to prevent metal corrosion and improve service life and mechanical properties.
[0026] The bottom of the low-pressure depropanizer, which originally used steam as a heat source, contains a high concentration of readily polymerizable substances such as butadiene and cyclopentadiene. These substances are prone to polymerizing and forming coke at higher temperatures. Lowering the temperature significantly reduces the risk of polymerization and coking. Therefore, the process employs a method of reducing pressure to lower the bottom temperature.
[0027] This utility model adopts heat medium water with a lower temperature than steam as the heat source of the reboiler at the bottom of the tower. Due to the reduction of the temperature of the heat source, the risk of coking caused by high temperature at the bottom of the tower (especially inside the reboiler) is further reduced.
[0028] Since the heat source of this utility model is the waste heat recovered from the ethylene plant, the refinery, the aromatics plant or the condensation, the steam consumption of the whole plant will be reduced after adopting this utility model, which is beneficial to reduce the energy consumption of the device and the carbon dioxide emission of the whole plant.
[0029] It is worth noting that the entire device is controlled by a master control device. Since the devices matched with the control device are commonly used devices and belong to existing mature technologies, their electrical connection relationships and specific circuit structures will not be described in detail here.
[0030] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A device for reducing coking in a low-pressure depropanizer reboiler, characterized in that: The invention comprises a low-pressure depropanizer (1), wherein a condensate stripping tower (3) is provided on the low-pressure depropanizer (1), a deethanizer (2) is provided above the condensate stripping tower (3), a plurality of reboilers (18) connected in series are connected to the low-pressure depropanizer (1), and a cutting tower (12) is connected to the side of the reboiler (18) close to the low-pressure depropanizer (1), and a reflux tank (11) is connected to one end of the plurality of reboilers (18) away from the low-pressure depropanizer (1), and a reflux pump (8) and a feed pump (9) are respectively connected to one side of the reflux tank (11), and the feed pump (9) is connected to the high-pressure depropanizer. (10), one end of the reflux pump (8) away from the reflux tank (11) is connected to the low-pressure depropanizer (1), and the connection between the reflux pump (8) and the low-pressure depropanizer (1) is connected to the feed and discharge heat exchanger (7), the side of the low-pressure depropanizer (1) is connected to a reboiler (18), the upper and lower ends of the reboiler (18) are respectively connected to the side and bottom of the low-pressure depropanizer (1), and one side of the reboiler (18) is connected to a hot water tank (13), the bottom of the hot water tank (13) is connected to a hot water circulation pump (15), and the hot water circulation pump (15) is connected to a heat extraction device (14).
2. A device for reducing coking in a low-pressure depropanizer reboiler according to claim 1, characterized in that: The bottom of the low-pressure depropanizer (1) is connected to a debutanizer (6).
3. A device for reducing coking in a low-pressure depropanizer reboiler according to claim 1, characterized in that: The bottom of the low-pressure depropanizer (1) is connected to the reboiler (18), the upper end of the reboiler (18) is connected to the side of the low-pressure depropanizer (1), and both sides of the reboiler (18) are respectively connected to the low-pressure steam pipe network (4) and the steam condensate tank (5).
4. The device for reducing coking in a low-pressure depropanizer reboiler according to claim 1, wherein: The heat extraction device (14) is connected to the reboiler (18).
5. The device for reducing coking in a low-pressure depropanizer reboiler according to claim 1, wherein: A water supply port (17) is provided on one side of the hot water tank (13), and a nitrogen port (16) is provided on a side of the hot water tank (13) away from the water supply port (17).