A device for increasing the heat exchange effect of a methanol reaction gas heat exchanger

Abstract

A device for increasing the heat exchange efficiency of a methanol reaction gas heat exchanger belongs to the field of methanol-to-olefins technology. It comprises a feeding hopper, shut-off valves, a pressure tank, a local pressure gauge, and a methanol reaction gas heat exchanger. The bottom of the feeding hopper is connected to the top of the pressure tank via a pipeline equipped with a first shut-off valve. A second shut-off valve is located between the pressurized nitrogen pipeline and the pressure tank. The bottom of the pressure tank is connected to the tube-side inlet of both the first and second methanol reaction gas heat exchangers via pipelines equipped with a third shut-off valve. Nitrogen pipelines are connected to the tube-side inlet of both the first and second methanol reaction gas heat exchangers via fourth and fifth shut-off valves. This invention utilizes the pressure stored in the pressure tank and the nitrogen supply to deliver calcium hydroxide particles to the upper end of the tube side of the methanol reaction gas heat exchanger, causing them to flush the inner wall of the tube side from top to bottom, thereby increasing the heat exchange efficiency, reducing energy loss, and decreasing the load on the water system.

Description

Technical Field

[0001] This utility model belongs to the field of methanol-to-olefins technology, specifically relating to a device for increasing the heat exchange effect of a methanol reaction gas heat exchanger. Background Technology

[0002] In the methanol-to-olefins (MTO) process, the gasified methanol undergoes chain growth under high temperature and catalyst conditions, producing product gas mainly composed of low-carbon alkanes and olefins such as ethylene and propylene. The high-temperature product gas generated in the reactor needs to be cooled to a certain temperature before entering the separation unit compressor for compression. To increase energy efficiency and reduce the burden on the water system, methanol product gas heat exchangers are commonly used in the MTO process to cool the product gas while simultaneously heating the gaseous methanol. Because the product gas contains some long-chain alkanes, olefins, and oxygen-containing organic compounds, a layer of organic matter forms an oily sludge that adheres to the inner wall of the tubes carrying the product gas after prolonged operation. Furthermore, the heat exchangers are typically large, making offline cleaning impossible during operation. Therefore, in current industrial MTO production, methanol product gas heat exchangers commonly suffer from reduced heat exchange efficiency and energy utilization due to the accumulation of large amounts of oil on the inner wall of the tubes after prolonged operation, while also significantly increasing the load on the water system.

[0003] To address the problems existing in the methanol product gas heat exchanger in the current methanol-to-olefins process, this invention addresses these issues by installing a calcium hydroxide feeding hopper, a pressure tank, a pressurized nitrogen pipeline, and a nitrogen delivery pipeline at the lower end of the methanol product gas heat exchanger. This allows calcium hydroxide granules to be added to the tube side of the heat exchanger, flushing the tube side from bottom to top and removing oil deposits from the inner wall of the tube side to the greatest extent possible, thereby improving the heat exchanger's heat exchange efficiency. Utility Model Content

[0004] The purpose of this invention is to provide a device that increases the heat exchange efficiency of a methanol reaction gas heat exchanger, thereby improving the heat exchange efficiency of the methanol product gas heat exchanger.

[0005] This utility model discloses a device for increasing the heat exchange effect of a methanol reaction gas heat exchanger, comprising a feeding hopper, a first shut-off valve, a second shut-off valve, a third shut-off valve, a fourth shut-off valve, a fifth shut-off valve, a pressure tank, a local pressure gauge, a first methanol reaction gas heat exchanger, and a second methanol reaction gas heat exchanger. The bottom of the feeding hopper is connected to the top of the pressure tank via a pipeline equipped with the first shut-off valve. The second shut-off valve is located between the pressurized nitrogen pipeline and the pressure tank. The local pressure gauge is located at the top of the pressure tank. The bottom of the pressure tank is connected to the tube-side inlet of both the first and second methanol reaction gas heat exchangers via pipelines equipped with the third shut-off valve. The nitrogen pipeline is connected to the tube-side inlet of both the first and second methanol reaction gas heat exchangers via the fourth and fifth shut-off valves. The tube-side outlets of both the first and second methanol reaction gas heat exchangers are connected to a quench tower via pipelines.

[0006] The working process of this utility model:

[0007] like Figure 1 As shown, when the heat exchange effect of the methanol reaction gas heat exchanger is poor, irregular cylindrical calcium hydroxide particles with a particle size of 2.5-5mm are poured into the feeding hopper, the second, third, fourth and fifth shut-off valves are closed, and the first shut-off valve is opened to add calcium hydroxide into the pressure storage tank; after the addition is completed, the second shut-off valve is opened and the first shut-off valve is closed, and the pressure storage tank is pressurized to the reading of 0.45-0.55MPa on the field pressure gauge using the pressurized nitrogen pipeline. After pressurization, the fourth and fifth shut-off valves are opened first, and nitrogen gas at 0.25-0.3 MPa is introduced into the tube-side inlet of the first and second methanol reaction gas heat exchangers using the nitrogen supply pipeline. Then, the second shut-off valve is closed and the third shut-off valve is opened. The pressure in the storage tank is used to transport calcium hydroxide particles into the tube-side inlet of the first and second methanol reaction gas heat exchangers. Driven by the supplied nitrogen, the calcium hydroxide particles are flushed from top to bottom in the tube-side of the heat exchangers. After flushing, the calcium hydroxide particles enter the quench tower through the tube-side outlet of the first and second methanol reaction gas heat exchangers and then dissolve in the quench water.

[0008] Advantages of this utility model:

[0009] (1) Adding calcium hydroxide particles from top to bottom in the tube side of the methanol reaction gas heat exchanger can effectively flush away oil stains and other impurities attached to the inner wall of the heat exchanger tube side, and at the same time reduce the probability of calcium hydroxide particles clogging the pipeline.

[0010] (2) Installing a pressure tank and pressurizing it with nitrogen can prevent the product gas in the heat exchanger tube side from being contaminated by other gases. At the same time, after the pressure tank reaches a certain pressure, opening the bottom shut-off valve can quickly push the calcium hydroxide particles into the tube side of the methanol reaction gas heat exchanger, avoiding blockage of the delivery pipeline.

[0011] (3) Add a nitrogen pipeline and open the shut-off valve of the nitrogen pipeline in advance. Under the combined push of the nitrogen and the pressure stored in the storage tank, the calcium hydroxide particles can quickly flush the inner wall of the methanol reaction gas heat exchanger tube and avoid blockage in the tube. Attached Figure Description

[0012] 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.

[0013] Figure 1 This is a schematic diagram of the device structure for increasing the heat exchange effect of the methanol reaction gas heat exchanger according to the present invention.

[0014] Figure 2 A comparison of the heat exchange effects of the methanol reaction gas heat exchanger before and after adding calcium hydroxide in the 1.8 million tons / year methanol-to-olefins process.

[0015] Figure 3 A graph showing the temperature trends of the tube side and shell side of the methanol reaction gas heat exchanger in a 1.8 million tons / year methanol-to-olefins process within one month after the addition of calcium hydroxide. Detailed Implementation

[0016] Example 1

[0017] like Figure 1 As shown, the feeding hopper 1 is a conical hopper with a volume of 100L; the first shut-off valve 2, the second shut-off valve 5, the third shut-off valve 6, the fourth shut-off valve 9, and the fifth shut-off valve 10 are DN20 straight-through shut-off valves; the pressure tank 3 is a sealed storage tank with a volume of 100L; the field pressure gauge 4 is a field pressure gauge with a range of 0.6MPa; the first methanol reaction gas heat exchanger 7 and the second methanol reaction gas heat exchanger 8 are NES3800-0.39 / 0.69-2426-11.6 / 89-I type heat exchangers.

[0018] In the methanol-to-olefins process using a methanol reaction gas heat exchanger, when the heat exchange effect of the methanol reactor heat exchanger is poor, a bucket of calcium hydroxide granules (40 kg / bucket, 4 mm particle size) is poured into the feeding hopper 1. The second shut-off valve 5, the third shut-off valve 6, the fourth shut-off valve 9, and the fifth shut-off valve 10 are closed, and the first shut-off valve 2 is opened to add calcium hydroxide into the pressure storage tank 3. After the addition is completed, the second shut-off valve 5 is opened and the first shut-off valve 2 is closed. The pressure storage tank 3 is pressurized using the pressurized nitrogen pipeline until the reading on the field pressure gauge 4 is 0.5 MPa. After pressurization, the fourth shut-off valve 9 and the fifth shut-off valve 10 are opened first. Nitrogen gas at 0.25 MPa is introduced into the tube-side inlet of the first methanol reaction gas heat exchanger 7 and the second methanol reaction gas heat exchanger 8 through the nitrogen supply pipeline. Then, the second shut-off valve 5 is closed and the third shut-off valve 6 is opened. The pressure in the pressure tank 3 is used to transport calcium hydroxide particles into the tube-side inlet of the first methanol reaction gas heat exchanger 7 and the second methanol reaction gas heat exchanger 8. Driven by the supplied nitrogen gas, the calcium hydroxide particles are flushed from top to bottom in the tube-side of the heat exchanger. After flushing, the calcium hydroxide particles enter the quench tower through the tube-side outlet of the first methanol reaction gas heat exchanger 7 and the second methanol reaction gas heat exchanger 8, and then dissolve in the quench water.

[0019] like Figure 2 As shown: After adding calcium hydroxide for 8 minutes, the inlet and outlet temperatures of the heat exchanger tubes and shell side changed significantly, with the tube side temperature decreasing by 7°C and the shell side temperature increasing by 4°C. Simultaneously, from... Figure 3 It can be seen that after adding calcium hydroxide, the good heat exchange effect of the methanol reactor heat exchanger can be maintained for about 30 days.

[0020] From the above description, it can be seen that the present invention achieves the following technical effects:

[0021] 1. After installing the device to enhance the heat exchange effect of the methanol reaction gas heat exchanger, the outlet temperatures of the shell side and tube side of the methanol reaction gas heat exchanger began to change significantly 8 minutes after adding calcium hydroxide. This indicates that the device of this invention can quickly add calcium hydroxide from bottom to top to flush the tube side.

[0022] 2. After installing the device to enhance the heat exchange effect of the methanol reaction gas heat exchanger, the outlet temperature of the product gas flowing through the tubes of the methanol reaction gas heat exchanger decreased from 267℃ to 260℃; the temperature of the methanol flowing through the shell increased from 257℃ to 261℃. The temperature changes indicate that the heat exchange effect was significantly improved after using calcium hydroxide for flushing.

[0023] 3. After installing the device to enhance the heat exchange efficiency of the methanol reaction gas heat exchanger, the tube-side temperature of the methanol reaction gas heat exchanger gradually increases and the shell-side temperature gradually decreases. After 30 days, it returns to the temperature before the addition of calcium hydroxide. That is, each addition of calcium hydroxide can enable the heat exchanger to maintain a good heat exchange capacity for 30 days.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 increasing the heat exchange efficiency of a methanol reaction gas heat exchanger, characterized in that: It consists of a feeding hopper (1), a first shut-off valve (2), a second shut-off valve (5), a third shut-off valve (6), a fourth shut-off valve (9), a fifth shut-off valve (10), a pressure tank (3), a field pressure gauge (4), a first methanol reaction gas heat exchanger (7), and a second methanol reaction gas heat exchanger (8); wherein, the bottom of the feeding hopper (1) is connected to the top of the pressure tank (3) through a pipeline with the first shut-off valve (2), the second shut-off valve (5) is set between the pressurized nitrogen pipeline and the pressure tank (3), and the field pressure gauge (4) is set in the pressure tank. The upper part of the pressure tank (3); the bottom of the pressure tank (3) is connected to the tube-side inlet of the first methanol reaction gas heat exchanger (7) and the second methanol reaction gas heat exchanger (8) respectively through pipelines with a third shut-off valve (6); the nitrogen delivery pipeline is connected to the tube-side inlet of the first methanol reaction gas heat exchanger (7) and the second methanol reaction gas heat exchanger (8) respectively through a fourth shut-off valve (9) and a fifth shut-off valve (10); the tube-side outlets of the first methanol reaction gas heat exchanger (7) and the second methanol reaction gas heat exchanger (8) are connected to the quench tower through pipelines.

2. The device for increasing the heat exchange effect of a methanol reaction gas heat exchanger as described in claim 1, characterized in that: The feeding hopper (1) is a cone-shaped hopper with a volume of 100L.

3. The device for increasing the heat exchange effect of a methanol reaction gas heat exchanger as described in claim 1, characterized in that: The first shut-off valve (2), the second shut-off valve (5), the third shut-off valve (6), the fourth shut-off valve (9), and the fifth shut-off valve (10) are DN20 straight-through shut-off valves.

4. The device for increasing the heat exchange effect of a methanol reaction gas heat exchanger as described in claim 1, characterized in that: The pressure tank (3) is a closed storage tank with a volume of 100L.

5. The device for increasing the heat exchange effect of a methanol reaction gas heat exchanger as described in claim 1, characterized in that: The field pressure gauge (4) is a field pressure gauge with a range of 0.6 MPa.

6. The device for increasing the heat exchange effect of a methanol reaction gas heat exchanger as described in claim 1, characterized in that: The first methanol reaction gas heat exchanger (7) and the second methanol reaction gas heat exchanger (8) are NES3800-0.39 / 0.69-2426-11.6 / 89-I type heat exchangers.

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