Device for reducing backwashing fluctuation
By installing the cyclone desiccant above the wastewater tank and optimizing the flow paths of purified water and nitrogen, the problems of cyclone desiccant overflow and wastewater tank pressure fluctuations during the backwashing of the fluidized bed filter were solved, thus achieving stable operation of the process.
Patent Information
- Application Number
- CN202520352134.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-03-03
AI Technical Summary
In the methanol-to-olefins process, the cyclone dehydrator is prone to overflow during the backwashing of the fluidized bed filter, and the pressure of the wastewater tank fluctuates, affecting the stable operation of the process.
The cyclone desiccant is installed above the wastewater tank, and the top of the wastewater tank is connected to the bottom of the cyclone desiccant. The flow of purified water and nitrogen is controlled by a check valve to prevent the accumulation of purified water in the cyclone desiccant and pressure fluctuations in the wastewater tank.
This effectively avoids the overflow of the cyclone dehydrator and pressure fluctuations in the wastewater tank, ensuring the stability and safety of the process.
Smart Images
Figure CN223831866U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of methanol-to-olefins technology, specifically relating to a device for reducing backwashing fluctuations. Background Technology
[0002] In the methanol-to-olefins (MTO) process, the quench water scrubbing tower inevitably carries a large amount of small-particle solid catalyst into the water system after cooling the product gas. Therefore, it needs to be filtered by a fluidized bed filter to reduce the solid content in the quench water. After prolonged operation, the fluidized bed filter contains a large amount of impurities, resulting in a large pressure difference and poor filtration efficiency. Current MTO processes often use purified water and nitrogen for backwashing. The purified water and nitrogen used in the fluidized bed filter backwashing process are collected in a wastewater tank and then discharged to a sewage pond. Currently, the main problems in the fluidized bed filter backwashing process are as follows:
[0003] (1) Because the cyclone desiccant used in the backwashing process is installed at a position lower than the wastewater tank, the purified water spun out by the cyclone desiccant accumulates in the tank, which makes the cyclone desiccant easy to fill with liquid and the nitrogen gas discharged from the tank carry liquid.
[0004] (2) The separation effect of nitrogen and purified water during the backwashing process is poor. The purified water separated by the cyclone desliming tank is prone to carrying a large amount of nitrogen into the wastewater tank, causing a large amount of nitrogen in the wastewater tank, resulting in overpressure in the wastewater tank and affecting the stable operation of the process. Utility Model Content
[0005] The purpose of this invention is to provide a device for reducing backwashing fluctuations in the backwashing process of a fluidized bed filter, as well as pressure fluctuations in the cyclone dehydration tank and wastewater tank during the methanol-to-olefins process.
[0006] The utility model provides a device for reducing backwashing fluctuations, comprising a fluidized bed filter, a wastewater tank, a cyclone desiccant tank, and a wastewater pump. The top of the fluidized bed filter is connected to the upper middle part of the wastewater tank via a pipeline with a first shut-off valve, and the upper middle part of the fluidized bed filter is connected to the lower middle part of the wastewater tank via a pipeline with a second shut-off valve. The wastewater tank is located below the cyclone desiccant tank, and the top of the wastewater tank is connected to the bottom of the cyclone desiccant tank via a pipeline with a check valve. The upper part of the wastewater tank is connected to the upper middle part of the cyclone desiccant tank via a pipeline. The wastewater pump is located below the wastewater tank and connected to the wastewater tank via a pipeline. External nitrogen is connected to the top of the cyclone desiccant tank via a pipeline with a first shut-off valve, and the top of the cyclone desiccant tank is connected to a torch via a pipeline with a second shut-off valve.
[0007] To address the aforementioned problems in the backwashing process of the fluidized bed filter in the existing methanol-to-olefins process, this invention installs a cyclone dewatering tank above the wastewater tank, and connects the top of the wastewater tank to the bottom of the cyclone dewatering tank via a check valve to prevent the accumulation of large amounts of purified water in the cyclone dewatering tank. Furthermore, the nitrogen gas blown out during the backwashing of the fluidized bed filter is connected to the upper part of the wastewater tank via a first shut-off valve, and the upper part of the wastewater tank is connected to the upper part of the cyclone dewatering tank via a pipeline to discharge the nitrogen gas accumulated in the wastewater tank into the cyclone dewatering tank, thereby preventing process fluctuations caused by pressure fluctuations in the wastewater tank.
[0008] The working process of this utility model:
[0009] In the methanol-to-olefins process, nitrogen gas generated during the backwashing of the fluidized bed filter accumulates at the top of the filter. It then enters the upper middle part of the wastewater tank through the first shut-off valve, and after being blocked by the check valve, it enters the upper middle part of the cyclone dehydrator through the pipeline at the top of the wastewater tank. The nitrogen gas that has been dehydrated in the cyclone dehydrator enters the flare pipeline through the second shut-off valve and is then discharged. The purified water generated during the backwashing of the fluidized bed filter enters the lower middle part of the wastewater tank through the second shut-off valve. The purified water swirling out of the cyclone dehydrator flows back to the wastewater tank under the action of gravity through the check valve. The two streams of purified water merge and are then pumped to the wastewater tank by the wastewater pump.
[0010] After the backwashing process of the fluidized bed filter is completed, nitrogen and purified water are shut off. The wastewater tank still contains a large amount of purified water. At this time, the first shut-off valve is opened and the second shut-off valve is slightly opened to add external nitrogen to maintain the positive pressure of the flare pipeline. At the same time, the pressure of the wastewater tank is maintained to ensure that the purified water in the tank is stably output to the sewage pool by the wastewater pump, so as to avoid process fluctuations caused by the excessively low pressure of the wastewater tank.
[0011] The fluidized bed filter is an HC / BS-50 type fluidized bed filter with a processing capacity of 50t / h;
[0012] The first and second shut-off valves are pneumatic two-position shut-off valves.
[0013] The wastewater tank has a volume of 50m³. 3 The upright can;
[0014] The aforementioned cyclone dehydrator has a processing capacity of 300m³. 3 / h, vertical tank with specifications of Φ1000×2555×12;
[0015] The first and second shut-off valves are DN50 straight-through shut-off valves.
[0016] The wastewater pump mentioned is an OH2 type centrifugal pump;
[0017] The check valve is a DN20 lift check valve.
[0018] Advantages of this utility model:
[0019] (1) The cyclone dehydrator is installed directly above the wastewater tank to prevent the cyclone dehydrator from losing its function of removing moisture from nitrogen due to the presence of a large amount of purified water in the cyclone dehydrator. At the same time, by connecting the top of the wastewater tank with the bottom of the cyclone dehydrator, the purified water spun out of the cyclone dehydrator can flow into the wastewater tank in real time by gravity.
[0020] (2) The nitrogen and purified water from backwashing enter the upper and lower parts of the wastewater tank respectively. At the same time, the nitrogen in the wastewater tank can enter the cyclone desiccant in real time through the pipeline connected to the upper part of the cyclone desiccant, which effectively avoids the problem of nitrogen entering the wastewater tank and causing overpressure in most designs, and avoids the process fluctuations caused by this.
[0021] (3) The design of adding a nitrogen supply line can effectively maintain the positive pressure of the flare line and avoid accidents caused by the negative pressure of the flare line; at the same time, after the backwashing is completed, the external nitrogen supply can maintain the pressure of the wastewater tank to ensure the stability of the process.
[0022] (4) A check valve is installed on the direct connection line between the wastewater tank and the cyclone desiccant to prevent the purified water from being blocked by the upstream nitrogen gas. Attached Figure Description
[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0024] Figure 1 A schematic diagram of a device used to reduce backwash fluctuations;
[0025] Figure 2 Bar graphs showing the frequency of full liquid in the cyclone dehydration tank and the frequency of pressure fluctuation in the wastewater tank before and after the installation of the backwashing fluctuation reduction unit in a 1.8 million tons / year methanol-to-olefins process. Detailed Implementation
[0026] Example 1
[0027] like Figure 1 As shown, the test experiment used the backwashing process of the fluidized bed filter in the 1.8 million tons / year methanol-to-olefins process. The backwashing process of fluidized bed filter 1 requires approximately 50 t / h of purified water and 200 Nm³ of purified water. 3A nitrogen gas flow rate of / h is used for backflushing. The purified water after flushing enters the lower middle part of wastewater tank 4 through the second shut-off valve 3, while the nitrogen gas after flushing enters the upper middle part of wastewater tank 4 through the first shut-off valve 2. A cyclone descaling tank 5 is installed directly above wastewater tank 4. Nitrogen gas from wastewater tank 4 enters the upper middle part of cyclone descaling tank 5 through a pipeline without a check valve 9 at the top. After the water in the nitrogen gas is separated in cyclone descaling tank 5, the nitrogen gas is discharged through the second shut-off valve 7 into the flare pipeline. Simultaneously, because cyclone descaling tank 5 is installed directly above wastewater tank 4, the purified water separated from the nitrogen gas in cyclone descaling tank 5 can flow into wastewater tank 4 in a timely manner through the check valve 9, ensuring that cyclone descaling tank 5 does not become full or the liquid level is too high. This also avoids the problem of water entering the flare pipeline due to the discharged nitrogen gas containing a large amount of water. After the fluidized bed filter is flushed, open the first shut-off valve 6 and slightly open the second shut-off valve 7 to supply nitrogen to the cyclone desolvation tank 5 and wastewater tank 4 to ensure stable system pressure and maintain positive pressure in the flare pipeline.
[0028] In such Figure 2 After installing the device to reduce backwashing fluctuations of the fluidized bed filter, the frequency of backwashing the cyclone desiccant 5 being full of liquid each time decreased from 70% to 0, and the frequency of pressure fluctuations in the wastewater tank 5 due to unstable system pressure decreased from 80% to 0.
[0029] As can be seen from the above description, this utility model achieves the following technical effects:
[0030] 1. After installing the device to reduce backwash fluctuations, the frequency of the cyclone separator 5 becoming full during each backwash of the fluidized bed filter decreased from 70% to 0. This solved the problem of the cyclone separator 5 becoming full due to backwashing and prevented purified water from entering the flare pipeline;
[0031] 2. After installing the device to reduce backwash fluctuations, due to the addition of a nitrogen pressurization pipeline, the frequency of pressure fluctuations in wastewater tank 4 during each backwashing of the fluidized bed filter was reduced from 80% to 0, thus solving the problem of pressure fluctuations in wastewater tank 4 and the resulting process fluctuations caused by unstable system pressure during backwashing.
[0032] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various variations and modifications can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
[0033] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0034] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.
[0035] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.
Claims
1. A device for reducing backwash fluctuations, characterized in that: It consists of a fluidized bed filter (1), a wastewater tank (4), a cyclone desiccant (5), and a wastewater pump (8); the top of the fluidized bed filter (1) is connected to the upper middle part of the wastewater tank (4) through a pipeline with a first shut-off valve (2), and the upper middle part of the fluidized bed filter (1) is connected to the lower middle part of the wastewater tank (4) through a pipeline with a second shut-off valve (3); the wastewater tank (4) is located below the cyclone desiccant (5), and the top of the wastewater tank (4) is connected to the lower middle part of the wastewater tank (5) through a pipeline with a second shut-off valve (3). The pipeline with a check valve (9) is connected to the bottom of the cyclone dehydration tank (5), and the upper part of the wastewater tank (4) is connected to the upper middle part of the cyclone dehydration tank (5) through a pipeline; the wastewater pump (8) is located below the wastewater tank (4) and is connected to the wastewater tank (4) through a pipeline; the external nitrogen gas is connected to the top of the cyclone dehydration tank (5) through a pipeline with a first shut-off valve (6), and the top of the cyclone dehydration tank (5) is connected to the torch through a pipeline with a second shut-off valve (7).
2. The device for reducing backwash fluctuations as described in claim 1, characterized in that: The fluidized bed filter (1) is a HC / BS-50 type fluidized bed filter with a processing capacity of 50t / h.
3. The device for reducing backwash fluctuations as described in claim 1, characterized in that: The first shut-off valve (2) and the second shut-off valve (3) are pneumatic two-position shut-off valves.
4. The device for reducing backwash fluctuations as described in claim 1, characterized in that: Wastewater tank (4) has a volume of 50m³ 3 The upright can.
5. The device for reducing backwash fluctuations as described in claim 1, characterized in that: The hydrocyclone desolventizer (5) has a processing capacity of 300m³. 3 A vertical tank with a capacity of / h and a diameter of Φ1000×2555×12.
6. The device for reducing backwash fluctuations as described in claim 1, characterized in that: The first shut-off valve (6) and the second shut-off valve (7) are DN50 straight-through shut-off valves.
7. The device for reducing backwash fluctuations as described in claim 1, characterized in that: Wastewater pump (8) is an OH2 type centrifugal pump.
8. The device for reducing backwash fluctuations as described in claim 1, characterized in that: The check valve (9) is a DN20 lift check valve.