A dimethyl ester rectification column waste heat step recycling system

Abstract

The utility model relates to the technical field of energy -conserving in chemical process, specifically is a kind of dimethyl ester rectifying column waste heat stepwise recycling system, including high temperature grade heat exchanger, low temperature grade heat exchanger, high temperature heat user and low temperature heat user, the hot side entrance of high temperature grade heat exchanger is connected with column top steam export, and hot side export is connected with the hot side entrance of low temperature grade heat exchanger;The cold side entrance of low temperature grade heat exchanger is communicated with the second cold source pipeline outlet, and cold side export is communicated with low temperature heat user intake end by pipeline, and low temperature heat user goes out end and the second cold source pipeline intake end are communicated. The use of the application, by high temperature grade heat exchanger, low temperature grade heat exchanger respectively heat is delivered to high temperature heat user and low temperature heat user, so that the column top steam heat can be recovered from high to low step, and the different grade heat user demand is matched.

Description

Technical Field

[0001] This utility model belongs to the field of energy-saving technology in chemical processes, specifically a waste heat recovery and utilization system for a dimethyl ester distillation tower. Background Technology

[0002] In the production of dimethyl ester (DMC), distillation is a crucial purification step, but it is also a high-energy-consuming unit. The top of the distillation column produces a large amount of vapor (usually a mixture of dimethyl ester and methanol, etc.), which is at a high temperature and contains a significant amount of high-quality heat energy. Traditional methods typically use a single condenser to directly condense this vapor into liquid using cooling water (or air). This method results in a large amount of high-quality heat energy being directly carried away by the low-grade cooling medium, leading to waste and low energy efficiency. Utility Model Content

[0003] This invention provides a waste heat recovery and utilization system for a dimethyl ester distillation column to address the deficiencies in the prior art.

[0004] This utility model is achieved through the following technical solution: A waste heat recovery and utilization system for a dimethyl ester distillation column includes a high-temperature stage heat exchanger, a low-temperature stage heat exchanger, a high-temperature heat user, and a low-temperature heat user. The hot-side inlet of the high-temperature stage heat exchanger is connected to the top steam outlet of the column, and its hot-side outlet is connected to the hot-side inlet of the low-temperature stage heat exchanger. The cold-side inlet of the high-temperature stage heat exchanger is connected to the outlet of a first cold source pipeline, and its cold-side outlet is connected to the inlet of the high-temperature heat user via a pipeline. The outlet of the high-temperature heat user is also connected to the inlet of the first cold source pipeline. The cold-side inlet of the low-temperature stage heat exchanger is connected to the outlet of a second cold source pipeline, and its cold-side outlet is connected to the inlet of the low-temperature heat user via a pipeline. The outlet of the low-temperature heat user is also connected to the inlet of the second cold source pipeline.

[0005] In operation, the high-temperature overhead steam first enters the high-temperature stage heat exchanger, where it releases most of its sensible heat and part of its latent heat to the high-temperature heat transfer medium (such as heat transfer oil or high-pressure hot water), raising its temperature to a usable standard. The high-temperature heat transfer medium is then delivered to high-temperature heat users to provide heat, and after cooling, it returns to the high-temperature stage heat exchanger for reuse. The steam, cooled and partially condensed in the high-temperature stage heat exchanger, then enters the low-temperature stage heat exchanger, where it releases its remaining heat to the low-temperature heat transfer medium (such as soft water or low-pressure hot water), raising its temperature. The low-temperature heat transfer medium is then delivered to low-temperature heat users via a circulating pump to provide heat, and after cooling, it returns to the low-temperature stage heat exchanger for reuse. In this way, the heat from the overhead steam is recovered in stages from high to low, matching the needs of heat users with different heat grades.

[0006] Preferably, a U-shaped pipe is provided between the hot-side outlet of the high-temperature stage heat exchanger and the hot-side inlet of the low-temperature stage heat exchanger. The U-shaped pipe has its U-shaped opening facing upwards and its two ends bent to connect to the hot-side outlet of the high-temperature stage heat exchanger and the hot-side inlet of the low-temperature stage heat exchanger, respectively. The horizontal portion of the U-shaped pipe is vertically downwards and connected to a water collection tank. When steam containing condensate passes through the U-shaped pipe, the condensate flows into the water collection tank under gravity, thus collecting the condensate and preventing its direct discharge, which would cause the ground to become slippery.

[0007] Preferably, the hot-side outlet of the low-temperature heat exchanger is connected to one end of a lower horizontal pipe, and the other end of the lower horizontal pipe is bent upward and then bent horizontally. The lower horizontal pipe is connected to a water receiving tank, which enables the collection of condensate generated after passing through the low-temperature heat exchanger.

[0008] Preferably, the horizontal portion and lower horizontal section of the U-shaped pipe are both vertically downwards and connected to vertical pipes. The two vertical pipes are respectively connected to the upper pipe of the corresponding Y-shaped pipe, and the lower pipe of the Y-shaped pipe is connected to the water receiving tank. The Y-shaped pipes enable the unified collection of condensate into the water receiving tank.

[0009] Preferably, the transverse portion of the U-shaped tube and the lower transverse tube are provided with screw holes. The upper end of the vertical tube is threaded and connected to the screw holes. The lower end of the vertical tube is detachably connected to the upper end of the connecting pipe through a flange. The lower end of the connecting pipe is integrally connected and connected to the corresponding upper end of the Y-shaped tube. This makes the vertical tube detachable, which is convenient for cleaning the vertical tube and avoids blockage caused by the accumulation of impurities inside the vertical tube.

[0010] The beneficial effects of this utility model are as follows: By using the high-temperature stage heat exchanger and the low-temperature stage heat exchanger, heat is delivered to high-temperature heat users and low-temperature heat users respectively, thereby enabling the heat of the steam at the top of the tower to be recovered in stages from high to low, matching the needs of heat users of different grades. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of this utility model; As shown in the figure: 1. High-temperature stage heat exchanger; 2. Low-temperature stage heat exchanger; 3. U-tube; 4. Lower horizontal tube; 5. Vertical tube; 6. Y-tube; 7. Water receiving tank; 8. Flange. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. A waste heat recovery and utilization system for a dimethyl ester distillation column, such as Figure 1 As shown, it includes a high-temperature stage heat exchanger 1, a low-temperature stage heat exchanger 2, a high-temperature heat user, and a low-temperature heat user. Both the high-temperature stage heat exchanger 1 and the low-temperature stage heat exchanger 2 are plate heat exchangers, shell-and-tube heat exchangers, or spiral plate heat exchangers. The high-temperature heat user is equipment in the production process that requires a heat source of 80℃~110℃, such as a raw material preheater, reboiler, or heating system. The low-temperature heat user refers to equipment in the production process that requires a heat source of 40℃~80℃, such as a demineralized water heating system, a domestic hot water system, or a low-temperature material preheater. The hot-side inlet of the high-temperature stage heat exchanger 1 is connected to the steam outlet at the top of the tower, and the hot-side outlet is connected to the hot-side inlet of the low-temperature stage heat exchanger 2. The cold-side inlet of the high-temperature stage heat exchanger 1 is connected to the outlet of the first cold source pipeline, and the cold-side outlet is connected to the inlet of the high-temperature heat user through a pipeline. The outlet of the high-temperature heat user is connected to the inlet of the first cold source pipeline. The cold-side inlet of the low-temperature stage heat exchanger 2 is connected to the outlet of the second cold source pipeline, and the cold-side outlet is connected to the inlet of the low-temperature heat user through a pipeline. The outlet of the low-temperature heat user is connected to the inlet of the second cold source pipeline.

[0014] In operation, the high-temperature overhead steam first enters the high-temperature heat exchanger 1, where it releases most of its sensible heat and part of its latent heat to the high-temperature heat transfer medium (such as heat transfer oil or high-pressure hot water), raising its temperature to a usable level. The high-temperature heat transfer medium is then delivered to high-temperature heat users to provide heat, and after cooling, it returns to the high-temperature heat exchanger 1 for reuse. The steam, cooled and partially condensed in the high-temperature heat exchanger 1, then enters the low-temperature heat exchanger 2, where it releases its remaining heat to the low-temperature heat transfer medium (such as soft water or low-pressure hot water), raising its temperature. The low-temperature heat transfer medium is then delivered to low-temperature heat users via a circulating pump to provide heat, and after cooling, it returns to the low-temperature heat exchanger 2 for reuse. This method achieves a stepped recovery of the overhead steam heat from high to low temperatures, matching the needs of heat users with different heat grades.

[0015] A U-shaped pipe is installed between the hot-side outlet of the high-temperature stage heat exchanger 1 and the hot-side inlet of the low-temperature stage heat exchanger 2. The U-shaped pipe has its U-shaped opening facing upwards and its two ends bent to connect to the hot-side outlet of the high-temperature stage heat exchanger 1 and the hot-side inlet of the low-temperature stage heat exchanger 2, respectively. The horizontal portion of the U-shaped pipe is vertically downwards and connected to a water collection tank 7. When steam containing condensate passes through the U-shaped pipe, the condensate flows into the water collection tank 7 under gravity, thus collecting the condensate and preventing it from being directly discharged and causing the ground to become slippery.

[0016] The hot side outlet of the low-temperature heat exchanger 2 is connected to one end of the lower horizontal pipe 4. The other end of the lower horizontal pipe 4 is bent upward and then bent horizontally. The lower horizontal pipe 4 is connected to the water receiving tank 7, which can realize the collection of condensate generated after passing through the low-temperature heat exchanger 2.

[0017] The horizontal section of the U-shaped pipe and the lower horizontal pipe 4 are both vertically downward and connected to the vertical pipe 5. The two vertical pipes 5 are respectively connected to the upper pipe of the corresponding Y-shaped pipe, and the lower pipe of the Y-shaped pipe is connected to the water receiving tank 7. The Y-shaped pipe enables the condensate to be collected into the water receiving tank 7.

[0018] The transverse portion of the U-shaped tube and the lower transverse tube 4 are provided with screw holes. The upper end of the vertical tube 5 is threaded and connected to the screw holes. The lower end of the vertical tube 5 is detachably connected to the upper end of the connecting pipe through the flange 8. The lower end of the connecting pipe is integrally connected and connected to the corresponding upper end of the Y-shaped tube. This makes the vertical tube 5 detachable, which is convenient for cleaning the vertical tube 5 and avoids blockage caused by the accumulation of impurities inside the vertical tube 5.

[0019] The application of this technology uses high-temperature heat exchanger 1 and low-temperature heat exchanger 2 to transfer heat to high-temperature heat users and low-temperature heat users respectively, thereby enabling the heat of the top steam in the tower to be recovered in stages from high to low, matching the needs of heat users of different grades.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A waste heat recovery and utilization system for a dimethyl ester distillation column, characterized in that: It includes a high-temperature stage heat exchanger, a low-temperature stage heat exchanger, a high-temperature heat user, and a low-temperature heat user. The hot-side inlet of the high-temperature stage heat exchanger is connected to the steam outlet at the top of the tower, and the hot-side outlet is connected to the hot-side inlet of the low-temperature stage heat exchanger. The cold-side inlet of the high-temperature stage heat exchanger is connected to the outlet of the first cold source pipeline, and the cold-side outlet is connected to the inlet of the high-temperature heat user through a pipeline. The outlet of the high-temperature heat user is connected to the inlet of the first cold source pipeline. The cold-side inlet of the low-temperature stage heat exchanger is connected to the outlet of the second cold source pipeline, and the cold-side outlet is connected to the inlet of the low-temperature heat user through a pipeline. The outlet of the low-temperature heat user is connected to the inlet of the second cold source pipeline.

2. The waste heat recovery and utilization system for dimethyl ester distillation column according to claim 1, characterized in that: A U-shaped pipe is provided between the hot-side outlet of the high-temperature stage heat exchanger and the hot-side inlet of the low-temperature stage heat exchanger. The U-shaped opening of the U-shaped pipe faces upward and both ends are bent to connect to the hot-side outlet of the high-temperature stage heat exchanger and the hot-side inlet of the low-temperature stage heat exchanger, respectively. The horizontal part of the U-shaped pipe is vertically downward and connected to a water receiving tank.

3. The waste heat recovery and utilization system for dimethyl ester distillation column according to claim 2, characterized in that: The hot-side outlet of the low-temperature heat exchanger is connected to one end of a lower horizontal tube. The other end of the lower horizontal tube is bent upwards and then bent horizontally. The lower horizontal tube is connected to the water receiving tank.

4. The waste heat recovery and utilization system for dimethyl ester distillation column according to claim 3, characterized in that: The horizontal portion and lower horizontal tube of the U-shaped tube are both vertically downward and connected to a vertical tube. The two vertical tubes are respectively connected to the upper tube of the corresponding Y-shaped tube, and the lower tube of the Y-shaped tube is connected to the water receiving tank.

5. The waste heat recovery and utilization system for dimethyl ester distillation column according to claim 1, characterized in that: The horizontal section of the U-shaped tube and the lower horizontal tube are both provided with screw holes. The upper end of the vertical tube is threaded into and connected to the screw holes. The lower end of the vertical tube is detachably connected to the upper end of the connecting tube via a flange. The lower end of the connecting tube is integrally connected to and connected to the upper end of the corresponding Y-shaped tube.

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