Low-energy-consumption coal-to-ethylene glycol rectification system

Abstract

The utility model relates to the technical field of coal glycol rectification, specifically relates to a low energy consumption's coal glycol rectification system, the utility model discloses methanol recovery tower, dehydration tower, dealcoholization tower and product tower that connect gradually, through setting first reboiler and second reboiler in methanol recovery tower kettle, utilize the heat of dealcoholization tower overhead gas phase material and product tower overhead gas phase material to heat evaporation methanol recovery tower kettle liquid, and condense dealcoholization tower overhead gas phase material and product tower overhead gas phase material simultaneously, through setting preheater on methanol recovery tower feed pipeline, utilize the polyester grade glycol preheating crude glycol of product tower side, and cool polyester grade glycol simultaneously, thereby reduced the steam consumption of methanol recovery tower, and also reduced the cold consumption of product tower overhead gas phase material, dealcoholization tower overhead gas phase material and polyester grade glycol of side, makes the energy consumption of entire glycol rectification system significantly reduced.

Description

Technical Field

[0001] This utility model relates to the field of coal-to-ethylene glycol distillation technology, specifically to a low-energy-consumption coal-to-ethylene glycol distillation system. Background Technology

[0002] In the coal-to-ethylene glycol process, the distillation step is crucial for separating impurities such as methanol, water, and ethanol from crude ethylene glycol to obtain polyester-grade ethylene glycol. Traditional coal-to-ethylene glycol distillation systems typically include a methanol recovery tower, a dehydration tower, a dealcoholization tower, and a product tower. The top vapor phase of the dealcoholization and product towers is cooled and condensed using waste heat boilers and condensers with boiler water and circulating water, or sometimes directly with circulating water. This results in ineffective utilization of the heat carried by the top vapor phase in the dealcoholization and product towers, leading to heat waste. Furthermore, the polyester-grade ethylene glycol collected from the product tower also has high sensible heat. Cooling this heat with circulating water causes significant energy waste, increases the load and operating costs of the circulating water system, and fails to meet energy-saving and consumption-reducing production requirements. Therefore, effectively recovering heat from the distillation process and achieving rational energy utilization has become an important direction for optimizing coal-to-ethylene glycol distillation systems. Utility Model Content

[0003] The purpose of this invention is to provide a low-energy-consumption coal-to-ethylene glycol distillation system. This system can use the heat carried by the gas phase at the top of the dealcoholization tower, the heat carried by the gas phase at the top of the product tower, and the heat carried by the polyester-grade ethylene glycol collected from the side of the product tower to heat the material in the methanol recovery tower, so that this part of the heat is effectively utilized, thereby reducing the steam consumption of the methanol recovery tower. At the same time, the gas phase at the top of the dealcoholization tower, the gas phase at the top of the product tower, and the polyester-grade ethylene glycol collected from the side of the product tower can be cooled and condensed, which greatly reduces the cooling energy consumption of the dealcoholization tower and the product tower.

[0004] To achieve the above objectives, this utility model provides the following technical solution: A low-energy coal-to-ethylene glycol distillation system includes a methanol recovery tower, a dehydration tower, a dealcoholization tower, and a product tower connected in sequence, and further includes a first reboiler, a second reboiler, and a preheater. The bottom outlet of the methanol recovery tower is connected to the inlet of the dehydration tower via a pipeline, the bottom outlet of the dehydration tower is connected to the inlet of the dealcoholization tower via a pipeline, and the bottom outlet of the dealcoholization tower is connected to the inlet of the product tower via a pipeline. The top vapor outlet of the dealcoholization tower is connected to the shell-side inlet of the first reboiler via a pipeline, and the top vapor outlet of the product tower is connected to the shell-side inlet of the second reboiler via a pipeline. The shell-side condensate outlets of both the first and second reboilers are connected to their respective reflux tanks via pipelines, and the outlets of their respective reflux tanks are connected to the dealcoholization tower via reflux pipes. The top reflux port of the product tower is connected; the shell-side non-condensable vapor outlets of the first and second reboilers are both connected to their respective circulating water condensers via pipelines, the condensate outlets of their respective circulating water condensers are connected to their respective reflux tanks via pipelines, and the non-condensable vapor outlets of their respective circulating water condensers are connected to their respective vacuum devices via pipelines; the tube-side inlets and outlets of the first and second reboilers are both connected to the bottom outlet of the methanol recovery tower via pipelines, forming a heat exchange loop at the bottom of the methanol recovery tower; the side outlet of the product tower is connected to the tube-side inlet of the preheater via a pipeline, the shell-side inlet of the preheater is connected to the crude ethylene glycol pipeline, the shell-side outlet is connected to the feed inlet of the methanol recovery tower via a pipeline, and the tube-side outlet of the preheater is the discharge port for polyester-grade ethylene glycol products.

[0005] Furthermore, the methanol recovery tower is also equipped with a third reboiler in the bottom of the tower.

[0006] Furthermore, the methanol recovery tower is a variable diameter recovery tower, comprising a large-diameter tower at the upper end and a small-diameter tower at the lower end; the first reboiler and the second reboiler are located at the bottom of the large-diameter tower, and the third reboiler is located at the bottom of the small-diameter tower.

[0007] Compared with the prior art, the beneficial effects of this utility model are: This invention reduces the steam consumption of the methanol recovery tower by installing a first reboiler and a second reboiler in the bottom of the methanol recovery tower. The heat carried by the vaporous material from the top of the dealcoholization tower and the product tower is used to heat and evaporate the liquid in the bottom of the methanol recovery tower, while simultaneously condensing the vaporous material from both towers. A preheater is installed on the feed line of the methanol recovery tower to preheat the crude ethylene glycol using polyester-grade ethylene glycol collected from the product tower, while simultaneously cooling the polyester-grade ethylene glycol. This reduces the energy consumption of the methanol recovery tower, as well as the cooling energy consumption of the vaporous material from the top of the product tower, the vaporous material from the dealcoholization tower, and the polyester-grade ethylene glycol collected from the product tower, resulting in a significant reduction in the overall energy consumption of the ethylene glycol distillation system. Attached Figure Description

[0008] Figure 1This is a schematic diagram of the structure of this utility model; In the diagram: 1-Methanol recovery tower; 2-Dehydration tower; 3-De-alcoholization tower; 4-Product tower; 5-Second reboiler; 6-Second circulating water condenser; 7-Second reflux tank; 8-Product tower top reflux pump; 9-First reboiler; 10-First circulating water condenser; 11-First reflux tank; 12-De-alcoholization tower top reflux pump; 13-Third reboiler; 14-Dehydration tower reboiler; 15-De-alcoholization tower reboiler; 16-Product tower reboiler; 17-Preheater; 18-Pipeline a; 19-Pipeline b; 20-Crude ethylene glycol pipeline. Detailed Implementation

[0009] The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this utility model, and are not limited to the scope of protection of the claims of this utility model. Example 1

[0010] refer to Figure 1To reduce the energy consumption of a coal-to-ethylene glycol distillation system, this invention provides a low-energy-consumption coal-to-ethylene glycol distillation system, comprising a methanol recovery tower 1, a dehydration tower 2, a dealcoholization tower 3, and a product tower 4 connected in sequence, and further including a first reboiler 9, a second reboiler 5, and a preheater 17; the bottom outlet of the methanol recovery tower 1 is connected to the inlet of the dehydration tower 2 via a pipeline, the bottom outlet of the dehydration tower 2 is connected to the inlet of the dealcoholization tower 3 via a pipeline, and the bottom outlet of the dealcoholization tower 3 is connected to the inlet of the product tower 4 via a pipeline; the top vapor outlet of the dealcoholization tower 3 is connected to the shell-side inlet of the first reboiler 9 via a pipeline, and the top vapor outlet of the product tower 4 is connected to the shell-side inlet of the first reboiler 9 via a pipeline. The pipe is connected to the shell-side inlet of the second reboiler 5. The shell-side condensate outlets of both the first reboiler 9 and the second reboiler 5 are connected to their respective reflux tanks via pipes. The outlets of their respective reflux tanks are connected to the top reflux ports of the dealcoholization column 3 and the product column 4 via reflux pipes. The shell-side non-condensable vapor outlets of both the first reboiler 9 and the second reboiler 5 are connected to their respective circulating water condensers via pipes. The condensate outlets of their respective circulating water condensers are connected to their respective reflux tanks via pipes. The non-condensable vapor outlets of their respective circulating water condensers are connected to their respective vacuum devices via pipes. That is, the shell-side condensate outlet of the first reboiler 9 is connected to the first reflux tank 11 via a pipe. The shell-side non-condensable vapor outlet of reboiler 9 is connected to the first circulating water condenser 10 via a pipeline. The condensate outlet of the first circulating water condenser 10 is connected to the corresponding first reflux tank 11 via a pipeline. The non-condensable vapor outlet of the first circulating water condenser 10 is connected to the corresponding vacuum device via pipeline a18. The outlet of the first reflux tank 11 is connected to the top reflux port of the desiccant 3 via the top reflux pump 12 and reflux pipe of the desiccant 3. The shell-side condensate outlet of the second reboiler 5 is connected to the second reflux tank 7 via a pipeline. The shell-side non-condensable vapor outlet of the second reboiler 5 is connected to the second circulating water condenser 6 via a pipeline. The condensate outlet of the second circulating water condenser 6 is connected to the corresponding second reflux tank 7 via a pipeline. The non-condensable steam outlet of the second circulating water condenser 6 is connected to the corresponding vacuum device through pipe b19; the outlet of the second reflux tank 7 is connected to the top reflux port of the product tower 4 through the product tower top reflux pump 8 and reflux pipe; the tube-side inlet and tube-side outlet of the first reboiler 9 and the second reboiler 5 are both connected to the bottom outlet of the methanol recovery tower 1 through pipes, forming a heat exchange loop at the bottom of the methanol recovery tower 1; the side outlet of the product tower 4 is connected to the tube-side inlet of the preheater 17 through a pipe, the shell-side inlet of the preheater 17 is connected to the crude ethylene glycol pipe 20, the shell-side outlet is connected to the feed inlet of the methanol recovery tower 1 through a pipe, and the tube-side outlet of the preheater 17 is the outlet of polyester-grade ethylene glycol product.The methanol recovery tower 1 is also equipped with a third reboiler 13 in the bottom of the tower; the methanol recovery tower 1 is a variable diameter recovery tower, including a large diameter tower at the upper end and a small diameter tower at the lower end; the first reboiler 9 and the second reboiler 5 are located in the bottom of the large diameter tower, and the third reboiler 13 is located in the bottom of the small diameter tower.

[0011] The dehydration tower 2, the deethanolation tower 3, and the product tower 4 are respectively equipped with a dehydration tower reboiler 14, a deethanolation tower reboiler 15, and a product tower reboiler 16.

[0012] The working principle of this utility model is as follows: By installing a first reboiler 9 and a second reboiler 5 in the bottom of the methanol recovery tower 1, the heat carried by the gaseous material at the top of the dealcoholization tower 3 and the gaseous material at the top of the product tower 4 is used to heat and evaporate the liquid at the bottom of the methanol recovery tower 1, while simultaneously condensing the gaseous material at the top of the dealcoholization tower 3 and the gaseous material at the top of the product tower 4. By installing a preheater 17 on the feed pipeline of the methanol recovery tower 1, the crude ethylene glycol is preheated using the polyester-grade ethylene glycol collected from the side of the product tower 4, while simultaneously cooling the polyester-grade ethylene glycol. This reduces the steam consumption of the methanol recovery tower 1, and also reduces the cooling energy consumption of the gaseous material at the top of the product tower 4, the gaseous material at the top of the dealcoholization tower 3, and the polyester-grade ethylene glycol collected from the side, thus significantly reducing the energy consumption of the entire ethylene glycol distillation system.

[0013] 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 alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims.

Claims

1. A low-energy coal-to-ethylene glycol distillation system, comprising a methanol recovery tower, a dehydration tower, a deethanolination tower, and a product tower connected in sequence, characterized in that: It also includes a first reboiler, a second reboiler, and a preheater; the bottom outlet of the methanol recovery tower is connected to the inlet of the dehydration tower via a pipeline, the bottom outlet of the dehydration tower is connected to the inlet of the dealcoholization tower via a pipeline, and the bottom outlet of the dealcoholization tower is connected to the inlet of the product tower via a pipeline; the top vapor outlet of the dealcoholization tower is connected to the shell-side inlet of the first reboiler via a pipeline, and the top vapor outlet of the product tower is connected to the shell-side inlet of the second reboiler via a pipeline; the shell-side condensate outlets of both the first and second reboilers are connected to their respective reflux tanks via pipelines, and the outlets of their respective reflux tanks are connected to the top reflux outlets of the dealcoholization tower and the product tower via reflux pipes; the first reboiler... The shell-side non-condensable vapor outlets of the first and second reboilers are connected to their respective circulating water condensers via pipelines. The condensate outlets of the respective circulating water condensers are connected to their respective reflux tanks via pipelines. The non-condensable vapor outlets of the respective circulating water condensers are connected to their respective vacuum devices via pipelines. The tube-side inlets and outlets of the first and second reboilers are connected to the bottom outlet of the methanol recovery tower via pipelines, forming a heat exchange loop at the bottom of the methanol recovery tower. The side outlet of the product tower is connected to the tube-side inlet of the preheater via a pipeline. The shell-side inlet of the preheater is connected to the crude ethylene glycol pipeline, and the shell-side outlet is connected to the feed inlet of the methanol recovery tower via a pipeline. The tube-side outlet of the preheater is the discharge outlet for polyester-grade ethylene glycol.

2. The low-energy coal-to-ethylene glycol distillation system according to claim 1, characterized in that: The methanol recovery tower is also equipped with a third reboiler.

3. The low-energy coal-to-ethylene glycol distillation system according to claim 1, characterized in that: The methanol recovery tower is a variable diameter recovery tower, comprising a large-diameter tower at the top and a small-diameter tower at the bottom; the first and second reboilers are located at the bottom of the large-diameter tower, and the third reboiler is located at the bottom of the small-diameter tower.

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