Drainage device for outlet steam of tube furnace before entering regenerator

Abstract

The utility model relates to a crude benzol distillation auxiliary device technical field, especially a pipe -still outlet steam is arranged in the drainage device before regenerator, including steam main pipe, its characterized in that, steam main pipe's import end is fixedly communicated with the export end of pipe -still, steam main pipe's export end is fixedly communicated with the import end of regenerator, the import end of drainage pipe is fixedly communicated with the lower edge of steam main pipe, the import end of drainage valve is flange -connected with the export end of drainage pipe, the import end of front venting pipe is flange -connected with the export end of drainage valve, the import end of stop valve is flange -connected with the export end of front venting pipe, the import end of rear venting pipe is fixedly communicated with the export end of stop valve, and steam dryness meter interface is installed on the front venting pipe.

Description

Technical Field

[0001] This utility model relates to the technical field of auxiliary devices for crude benzene distillation, and in particular to a drainage device for the steam at the outlet of a tubular furnace before it enters the regenerator. Background Technology

[0002] In the crude benzene distillation process, the tubular furnace is the core heating equipment. It heats the steam in the steam pipes to provide a stable source of heat or process medium for subsequent regenerators and the crude benzene distillation system (such as the benzene stripping tower and lean / rich oil heat exchangers). The start-up processes of the tubular furnace and the crude benzene distillation system are strongly interconnected, as detailed below: 1. Start-up characteristics of tubular furnace: The start-up of a tubular furnace requires three stages: ignition and heating → medium preheating → stable output. Among them, the steam pipeline is a key medium channel in the tubular furnace. Steam needs to be introduced into the pipeline during the heating stage to avoid dry burning of the pipeline (heating without medium can easily cause the pipeline to turn red). 2. Sensitivity of crude benzene distillation system: The crude benzene distillation system has extremely high requirements for the "dryness" of the feed medium. If the steam carries a large amount of condensate (steam water), it will quickly vaporize or mix with the process oil after entering the system, breaking the "oil-gas" balance in the system and causing drastic fluctuations in key parameters such as tower pressure and tower top temperature. 3. Limitations of the existing process: Currently, the steam connection between the tubular furnace and the crude benzene distillation system in the industry is a direct connection structure of "tubular furnace → steam pipeline → regenerator → crude benzene distillation system", without an intermediate dehydration and venting link. It is impossible to achieve a balance between "preventing the pipeline from overheating" and "avoiding system pressure fluctuations", which has become a key bottleneck restricting start-up efficiency and safety.

[0003] Based on the aforementioned existing technology, it can be seen that the following objective shortcomings exist in the joint operation of the tubular furnace and the crude benzene distillation system: (1) Prominent safety hazards: When the tubular furnace is started and heated, if steam is not introduced in order to save steam or simplify operation, the steam pipeline is in a "no medium heating" state. The furnace temperature of the tubular furnace will cause the pipeline temperature to rise sharply to more than 600℃, resulting in coarse grains and reduced strength of the pipeline material (such as 20# steel). Cracks are likely to occur in the short term, and in the long term, steam leakage or even fire risk may occur. (2) Poor system stability: If steam is introduced to prevent the pipeline from burning red, a large amount of condensate will be generated during the steam transportation process due to the decrease in ambient temperature (the steam water content can reach 10%-20%). The existing direct connection process will directly carry this water into the crude benzene distillation system, causing the system pressure to fluctuate by more than ±10% within 10-15 minutes, resulting in problems such as a decrease in the purity of the top product of the benzene stripping tower and scaling of the lean and rich oil heat exchangers. (3) High operating costs: In order to alleviate pressure fluctuations, operators need to frequently adjust the steam intake and open the system vent valve to release pressure, which not only increases labor intensity but also causes steam waste and makes it difficult to ensure safe operation. Utility Model Content

[0004] To address the above situation and overcome the shortcomings of existing technology, this utility model provides a drainage device for the steam outlet of a tubular furnace before it enters the regenerator. The technical solution it provides includes a steam main pipe, characterized in that the inlet end of the steam main pipe is fixedly connected to the outlet end of the tubular furnace, the outlet end of the steam main pipe is fixedly connected to the inlet end of the regenerator, the lower edge of the steam main pipe is fixedly connected to the inlet end of a drain pipe, the outlet end flange of the drain pipe is connected to the inlet end of a drain valve, the outlet end flange of the drain valve is connected to the inlet end of a front vent pipe, the outlet end flange of the front vent pipe is connected to the inlet end of a shut-off valve, the outlet end of the shut-off valve is fixedly connected to the inlet end of a rear vent pipe, and a steam dryness meter interface is installed on the front vent pipe.

[0005] Preferably, the outlet end of the vent pipe is fixedly connected to a sewage collection tank.

[0006] The beneficial effects of this utility model are: 1. Completely eliminate safety hazards. During the start-up phase, there is always medium flowing in the steam pipeline. When the tubular furnace is heating, the pipeline temperature is controlled at 150-200℃ to completely avoid the phenomenon of the pipeline turning red and eliminate safety risks such as steam leakage and fire caused by pipeline cracking.

[0007] 2. Significantly stabilizes the system. The pressurized steam condensate is vented before entering the crude benzene distillation system, reducing the system pressure fluctuation from more than ±10% to within ±3%, effectively avoiding abnormal operating conditions such as safety valve tripping and reduced tower separation efficiency.

[0008] 3. Significantly reduces operating costs. Operators no longer need to frequently adjust the steam volume, reducing labor intensity by more than 50%. At the same time, steam loss is reduced by 15%-20%, which can reduce energy costs by approximately 10,000-20,000 yuan per year.

[0009] 4. It has wide applicability. This solution is not only applicable to crude benzene distillation systems, but can also be extended to steam-linked start-up scenarios of "tubular furnace + subsequent reaction / separation system" in fields such as coking and coal chemical industry, such as coal tar distillation and methanol synthesis. It has a wide range of applications and strong reusability. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the present invention.

[0011] Attached Figure

[0012] 1. Steam main pipe, 2. Drain pipe, 3. Drain valve, 4. Front vent pipe, 5. Shut-off valve, 6. Rear vent pipe, 7. Steam dryness meter interface, 8. Wastewater collection tank. Detailed Implementation

[0013] The following is in conjunction with the appendix Figure 1 The specific embodiments of this utility model will be described in further detail.

[0014] In Example 1, the technical solution is to add a drain-vent assembly to the main steam pipe 1 between the tubular furnace outlet and the regenerator inlet. The specific operation is as follows: A drain valve 3 is installed at the lower edge of the main steam pipe 1 via a drain pipe 2. The drain valve 3 is a stainless steel gate valve 5, model J41W-16P, with a nominal diameter of DN80, suitable for the steam pipe diameter, withstanding temperatures ≤425℃ and pressures ≤1.6MPa, meeting the steam parameter requirements of the crude benzene distillation system. A front vent pipe 4 is welded downstream of the drain valve 3. The front vent pipe 4 is made of 20# steel, with a nominal diameter of DN50, one size smaller than the main steam pipe 1, to prevent excessive steam velocity during venting. A gate valve 5, model J11W-16C, is installed at the end of the front vent pipe 4 to control the venting volume. A wastewater collection tank 8 is connected downstream of the gate valve 5 via a rear vent pipe 6, facilitating access to the plant's wastewater collection pool via the wastewater collection tank 8.

[0015] Specifically, this application retains the original main steam valve at the regenerator inlet during operation, forming a complete process of "tubular furnace → main steam pipe 1 → drain valve 3 → main valve → regenerator → crude benzene distillation system". This solution achieves safe start-up through the logic of "step-by-step venting, quality assessment, and smooth switching," as detailed below: Phase 1, Tubular Furnace Heating and Venting: Close the main valve at the regenerator inlet, open the added drain valve 3 and the shut-off valve 5 at the end of the front vent pipe 4 to connect the steam main pipe 1 with the venting system; introduce low-pressure steam (pressure 0.2-0.3MPa) into the tubular furnace steam pipe. When the steam flows in the pipe, the condensate (steam water) it carries enters the front vent pipe 4 through the drain pipe 2 and drain valve 3, and then is discharged into the wastewater collection tank 8 through the shut-off valve 5 and the rear vent pipe 6 to prevent water from entering the crude benzene distillation system; at this time, the tubular furnace is normally ignited and heated. Because there is a medium flowing in the steam pipe, the temperature is controlled at 150-200℃, and there is no risk of red-hot. Phase 2, Steam quality detection: Steam is continuously introduced and kept in a venting state. Every 10 minutes, the steam dryness is sampled and detected through the preset steam dryness meter interface 7 on the front vent pipe 4. When the steam dryness is ≥95% in 3 consecutive test results, the steam quality is deemed qualified. At this time, the condensate content in the steam is ≤5%, which meets the requirements of the crude benzene distillation system. Phase 3, switch to normal: Open the main valve at the regenerator inlet, and at the same time gradually close the drain valve 3 and the shut-off valve 5 at the end of the front vent pipe 4 (synchronized in the opposite direction to the opening of the main valve; when the main valve is opened to 100%, the drain valve 3 is completely closed); after the switch is completed, the steam enters the regenerator stably through the main valve, and then enters the crude benzene distillation system. At this time, the system pressure fluctuation is controlled within ±3%, which meets the requirements of normal operation.

[0016] Example 2, based on Example 1, precisely targets the core node of steam water carryover problem "after the tubular furnace and before the regenerator", only adding drain valve 3 and front vent pipe 4 and rear vent pipe 6, without modifying the tubular furnace or crude benzene distillation system, with low modification cost (approximately 8,000-12,000 yuan per system) and short construction period (can be completed within 24 hours).

[0017] Furthermore, the aforementioned step-by-step control logic breaks away from the existing single operation mode of "either turn on steam or turn off steam." Through a three-step method of "first venting and draining water (water removal) → then detecting dryness (quality assessment) → finally switching processes (stable supply)," the problem of water carried over steam is completely resolved before it enters the crude benzene distillation system, achieving the dual goals of "preventing overheating" and "stabilizing pressure." Moreover, this application introduces "steam dryness ≥ 95%" as a quantitative standard for process switching, replacing the traditional reliance on operator experience, avoiding subjective errors, and ensuring the stability and repeatability of each start-up process.

[0018] In summary, this application has the following advantages: 1. Completely eliminates safety hazards. During the start-up phase, the steam pipeline always has a medium flowing. When the tubular furnace is heating, the pipeline temperature is controlled at 150-200℃, completely avoiding the phenomenon of the pipeline turning red-hot and eliminating safety risks such as steam leakage and fire caused by pipeline cracking; 2. Significantly stabilizes the system. The pressurized steam condensate is discharged through venting before entering the crude benzene distillation system. The system pressure fluctuation range is reduced from more than ±10% to within ±3%, effectively avoiding abnormal operating conditions such as safety valve tripping and decreased tower separation efficiency; 3. Significantly reduces operating costs. Operators do not need to frequently adjust the steam volume, reducing labor intensity by more than 50%. At the same time, steam loss is reduced by 15%-20%, which can reduce energy consumption costs by about RMB 10,000-20,000 per year; 4. Has wide applicability. This solution is not only applicable to the crude benzene distillation system, but can also be extended to the steam linkage start-up scenario of "tubular furnace + subsequent reaction / separation system" in the fields of coking and coal chemical industry, such as coal tar distillation and methanol synthesis. It has a wide range of applications and strong reusability.

Claims

1. A drainage device for steam from a tubular furnace outlet before it enters a regenerator, comprising a main steam pipe (1), characterized in that, The inlet end of the steam main pipe (1) is fixedly connected to the outlet end of the tubular furnace. The outlet end of the steam main pipe (1) is fixedly connected to the inlet end of the regenerator. The lower edge of the steam main pipe (1) is fixedly connected to the inlet end of the drain pipe (2). The outlet flange of the drain pipe (2) is connected to the inlet end of the drain valve (3). The outlet flange of the drain valve (3) is connected to the inlet end of the front vent pipe (4). The outlet flange of the front vent pipe (4) is connected to the inlet end of the stop valve (5). The outlet end of the stop valve (5) is fixedly connected to the inlet end of the rear vent pipe (6). A steam dryness meter interface (7) is installed on the front vent pipe (4).

2. The drainage device for the outlet steam of a tubular furnace before entering the regenerator according to claim 1, characterized in that, The outlet end of the rear vent pipe (6) is fixedly connected to a sewage collection tank (8).

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