Energy-saving rectification system for extracting xanthan gum ethanol solvent

Abstract

The utility model discloses an energy-saving rectification system for extracting a xanthan gum ethanol solvent, which comprises an ethanol rectification separation tower, an ethanol rectification tower bottom reboiler and a control end, and the ethanol rectification separation tower is sequentially connected with a preheating heat exchanger and a waste heat exchanger. Tower top distillate components of the ethanol rectification separation tower are connected with a compression system through a tower top distillate pipeline and are compressed by the compression system to be fed into a tower bottom reboiler of the ethanol rectification tower, a tower top flash tank is arranged at the tower top of the ethanol rectification separation tower, and a gas phase end of a flash evaporation part of the tower top flash tank is fed into the compression system; and the liquid phase of the tower top flash tank is sent back to the ethanol rectification separation tower through a circulating reflux system. According to the invention, the problem of newly increased energy consumption caused by the fact that a tower top gas phase needs to be cooled by circulating water and then is used as reflux and product delivery in traditional rectification is solved, and meanwhile, the heat exchange efficiency is higher by utilizing latent heat and sensible heat of the gas phase in overheating and saturation states; by adopting the technology, the energy consumption of a ton of products is obviously reduced, and the reduction rate reaches 34.14%.

Description

Technical Field

[0001] The present invention relates to the technical field of xanthan gum preparation and production, and specifically to a rectification system for extracting ethanol solvent for xanthan gum. Background Art

[0002] As a food additive and an oilfield exploitation aid, xanthan gum is mainly produced by Xanthomonas campestris. Its gel properties and bio-based properties have brought great market applications to the food industry and the oilfield exploitation industry.

[0003] As the core auxiliary agent for xanthan gum extraction, ethanol utilizes the alcohol-insoluble property of xanthan gum. Alcohol is added to the fermented mature liquid to precipitate xanthan gum, and then it is purified and dried to obtain high-quality xanthan gum products. The use of ethanol for xanthan gum extraction mainly includes several steps such as alcohol-liquid mixing, alcohol-liquid separation, and ethanol rectification and purification. Ethanol has the advantages of simple operation and low cost in the xanthan gum extraction process due to its unique properties.

[0004] In the xanthan gum ethanol rectification process, the traditional multi-effect ethanol rectification process is mostly used. This process is a technology that uses multiple rectification towers (or called effects) to achieve high-purity extraction of ethanol. Its basic principle is to reuse the energy supplied to the rectification tower to improve the thermodynamic efficiency. The specific process is as follows:

[0005] 1. Process characteristics;

[0006] 1) Replace a single tower with multiple towers and decompose a separation task into several towers with different operating pressures to complete;

[0007] 2) Each rectification tower becomes one effect. The top steam of the previous effect is used as the heating steam for the bottom reboiler of the next effect, and so on until the last tower;

[0008] 3) The operating pressures of each tower are different. The pressure of the previous effect is higher than that of the next effect, and the condensation temperature of the top steam of the previous effect is slightly higher than the boiling point temperature of the bottom liquid of the next effect;

[0009] The traditional multi-effect ethanol rectification process and equipment have the disadvantage of high energy consumption. Although multi-effect rectification is more energy-saving than a single-effect rectification tower through energy reuse, the entire rectification process still consumes a large amount of energy. This is because in the rectification tower, sufficient heat needs to be provided to evaporate the liquid and condense the steam back into the liquid, which involves a large amount of energy conversion and transfer processes. Currently, the energy consumption per ton of product of the traditional ethanol double-effect rectification in the industry has reached 0.041 tce / t. Therefore, a brand-new heat pump rectification system is proposed to reduce energy consumption. Utility Model Content

[0010] The purpose of the present utility model is to provide an energy-saving rectification system for extracting xanthan gum ethanol solvent, so as to solve the problems put forward in the above-mentioned background technology.

[0011] To achieve the above purpose, the present utility model provides the following technical solutions:

[0012] An energy-saving rectification system for extracting xanthan gum ethanol solvent, including an ethanol rectification separation tower, an ethanol rectification tower bottom reboiler and a control end. The ethanol rectification separation tower is sequentially connected to a preheating heat exchanger and a waste heat exchanger. The overhead distillate components of the ethanol rectification separation tower are connected to a compression system through an overhead distillate pipeline, and are sent to the ethanol rectification tower bottom reboiler after being compressed by the compression system.

[0013] As a further scheme of the present utility model: a top flash tank is arranged at the top of the ethanol rectification separation tower. The flashed part of the gas phase at the top flash tank is sent to the compression system, and the liquid phase of the top flash tank is sent back to the ethanol rectification separation tower through a circulating reflux system.

[0014] As a further scheme of the present utility model: the circulating reflux system includes an ethanol rectification tower reflux pump, a product external delivery pump and a reflux tank. The liquid phase of the top flash tank is sent into the reflux tank through the ethanol rectification tower reflux pump and the product external delivery pump, and the liquid phase in the reflux tank enters the ethanol rectification tower bottom reboiler through self-flow for circulation.

[0015] As a further scheme of the present utility model: the compression system includes a screw compressor and a liquid separation tank. The output end of the screw compressor is communicated with the liquid separation tank through a transmission pipeline, the liquid separation tank is communicated with the ethanol rectification tower bottom reboiler through a reboiler delivery pipeline, and the input end of the screw compressor is communicated with the overhead distillate pipeline.

[0016] As a further scheme of the present utility model: the liquid phase at the bottom of the liquid separation tank is communicated with the overhead distillate pipeline through a liquid supply pipeline to supply spraying liquid to the screw compressor. A temperature sensor is arranged on the transmission pipeline, and a regulating valve is arranged on the liquid supply pipeline. The control end controls the opening degree of the regulating valve through the electric signal of the temperature sensor to realize interlocking control.

[0017] As a further scheme of the present utility model: an external feeding and replenishing line for supplying ethanol to the input end of the screw compressor is connected to the overhead distillate pipeline. A reflux pipeline communicated with the reflux tank is also arranged at the liquid phase outlet of the liquid separation tank, and is sent back to the ethanol rectification separation tower through the reflux tank. Regulating valves are arranged on both the external feeding and replenishing line and the reflux pipeline. A liquid level sensor is installed on the liquid separation tank, and the control end controls the opening degree of the regulating valve through the electric signal of the liquid level sensor to realize interlocking control.

[0018] As a further solution of the present utility model: the reboiler delivery pipeline is communicated with the top distillate pipeline through a constant pressure pipeline, a regulating valve is arranged on the constant pressure pipeline, a pressure sensor is arranged on the top distillate pipeline, and the control end controls the opening degree of the regulating valve through the electrical signal of the pressure sensor to realize interlock control.

[0019] Compared with the prior art, the beneficial effects of the present utility model are:

[0020] The energy-saving distillation system for extracting xanthan gum ethanol solvent adopts a screw compressor to pressurize and heat the top gas-phase ethanol (0.01 Mpa, 80 °C) to 0.4 Mpa and 125 °C through the screw compressor inlet. After being pressurized, the gas phase is sent to the bottom reboiler of the ethanol distillation column to exchange heat with the kettle, thus greatly reducing the steam consumption. The gas phase after heat exchange at the top enters the collection tank, part of which is sent back to the top as reflux, and part of which is sent out as a product; the invention solves the additional energy consumption in traditional distillation where the top gas phase needs to be cooled by circulating water and then sent back as reflux and product, and at the same time utilizes the latent heat and sensible heat of the gas phase in the superheated and saturated states, with higher heat exchange efficiency; the energy consumption per ton of product using this technology has decreased significantly, and the decrease rate has reached 34.14%. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of an energy-saving distillation system for extracting xanthan gum ethanol solvent;

[0022] Figure 2 It is a schematic structural diagram of the compression system in an energy-saving distillation system for extracting xanthan gum ethanol solvent;

[0023] Figure 3 It is a table of energy consumption parameters of the prior art;

[0024] Figure 4 It is a table of energy consumption parameters of an energy-saving distillation system for extracting xanthan gum ethanol solvent.

[0025] In the figure: 1. Ethanol distillation and separation column; 2. Top flash tank; 3. Liquid separation tank; 4. Bottom reboiler of ethanol distillation column; 5. Reflux tank; 6. Screw compressor; 7. Preheating heat exchanger; 8. Waste heat exchanger; 9. Product delivery pump; 10. Waste water delivery pump; 11. Top distillate pipeline; 12. Transmission pipeline; 13. Recovery device; 14. Liquid supply pipeline; 15. Reboiler delivery pipeline; 16. External feeding and replenishing line; 17. Reflux pipeline. Detailed Embodiments

[0026] Please refer to Figures 1 to 4, in the embodiment of the present utility model, an energy-saving rectification system for extracting xanthan gum ethanol solvent includes an ethanol rectification separation tower 1, an ethanol rectification tower bottom reboiler 4 and a control end. The ethanol rectification separation tower 1 is sequentially connected to a preheating heat exchanger 7 and a waste heat exchanger 8. The overhead distillate components of the ethanol rectification separation tower 1 are connected to a compression system through an overhead distillate pipeline 11, and are compressed by the compression system and sent to the ethanol rectification tower bottom reboiler 4.

[0027] In a preferred embodiment, a top flash tank 2 is arranged at the top of the ethanol rectification separation tower 1. The flashed partial gas phase end of the top flash tank 2 is sent to the compression system, and the liquid phase of the top flash tank 2 is sent back to the ethanol rectification separation tower 1 through a circulating reflux system.

[0028] In a preferred embodiment, the circulating reflux system includes an ethanol rectification tower reflux pump, a product external delivery pump 9 and a reflux tank 5. The liquid phase of the top flash tank 2 is sent into the reflux tank 5 through the ethanol rectification tower reflux pump and the product external delivery pump 9, and the liquid phase in the reflux tank 5 enters the ethanol rectification tower bottom reboiler 4 for circulation by gravity.

[0029] In a preferred embodiment, the compression system includes a screw compressor 6 and a liquid separation tank 3. The output end of the screw compressor 6 is communicated with the liquid separation tank 3 through a transmission pipeline 12, the liquid separation tank 3 is communicated with the ethanol rectification tower bottom reboiler 4 through a reboiler delivery pipeline 15, and the input end of the screw compressor 6 is communicated with the overhead distillate pipeline 11.

[0030] In a preferred embodiment, the bottom liquid phase of the liquid separation tank 3 is communicated with the overhead distillate pipeline 11 through a liquid supply pipeline 14 to supply spraying liquid to the screw compressor 6. A temperature sensor is arranged on the transmission pipeline 12, and a regulating valve is arranged on the liquid supply pipeline 14. The control end controls the opening of the regulating valve through the electrical signal of the temperature sensor to achieve interlocking control.

[0031] In a preferred embodiment, an external feeding and replenishing line 16 for supplying ethanol to the input end of the screw compressor 6 is connected to the overhead distillate pipeline 11. A reflux pipeline 17 communicating with the reflux tank 5 is also arranged at the liquid phase outlet of the liquid separation tank 3 and is sent back to the ethanol rectification separation tower 1 through the reflux tank 5. Regulating valves are arranged on both the external feeding and replenishing line 16 and the reflux pipeline 17. A liquid level sensor is installed on the liquid separation tank 3, and the control end controls the opening of the regulating valve through the electrical signal of the liquid level sensor to achieve interlocking control.

[0032] In a preferred embodiment, the reboiler transfer pipeline 15 is connected to the top distillate pipeline 11 through a constant pressure pipeline 18. A regulating valve is provided on the constant pressure pipeline 18, and a pressure sensor is provided on the top distillate pipeline 11. The control end controls the opening degree of the regulating valve through the electrical signal of the pressure sensor to achieve interlock control. The present invention is composed of an ethanol distillation separation tower 1, a top flash tank 2, a supporting liquid separation tank 3, an ethanol distillation tower bottom reboiler 4, a reflux tank 5, a screw compressor 6, a waste heat exchanger 8, a preheating heat exchanger 7, an ethanol distillation tower reflux pump and a product external delivery pump 9, a waste water external delivery pump 10, and a control system.

[0033] The present invention belongs to a systematic energy-saving technology, and its main body is composed of two systems: the distillation system and the compression system of the ethanol distillation separation tower 1. Among them, the distillation system of the ethanol distillation separation tower 1 is composed of an ethanol distillation separation tower 1, a top flash tank 2, an ethanol distillation tower bottom reboiler 4, a reflux tank 5, a preheating heat exchanger 7, and a waste heat exchanger 8; the compression system is composed of a screw compressor 6 and a liquid separation tank 3. The main function of the distillation system of the ethanol distillation separation tower 1 is to separate ethanol and water; the compression system provides heat for the ethanol distillation separation tower 1 system. The recovery device 13 is connected to the reboiler transfer pipeline 15, and the excess part is discharged from the circulation system through the recovery device 13.

[0034] The present invention is an energy-saving technology, and the main process flow is as follows.

[0035] The raw material (low-concentration ethanol, an ethanol aqueous solution with 50%-55% V / V, 25°C) first undergoes the first step of preheating through the preheating heat exchanger 7, and the raw material is preheated to 50°C and then enters the waste heat exchanger 8 for the second step of waste heat utilization, and the raw material is preheated to 70°C and then enters the ethanol distillation separation tower 1. The ethanol-water raw material realizes gas-liquid separation on the internal trays of the ethanol distillation separation tower 1 according to the different boiling points of ethanol and water. Among them, the ethanol gas phase distills upward, and the waste water enters the bottom of the tower. It is continuously heated by the ethanol distillation tower bottom reboiler 4 at the bottom of the tower and the high-temperature phase (125°C) at the outlet of the screw compressor 6, and then the ethanol in the waste water is continuously stripped through the trays, so as to ensure that ethanol is distilled out from the top of the tower to the maximum extent. At the same time, the ethanol content in the bottom waste water can be guaranteed to be reduced to 0.02%. The bottom temperature of the ethanol distillation separation tower 1 is controlled at 102-105°C, and the bottom liquid level is controlled by the waste water external delivery pump 10 to keep it at a liquid level of 40-60%.

[0036] The ethanol vapor component distilled from the ethanol rectification separation column 1 enters the screw compressor 6 after passing through the filter via the overhead distillate pipeline 11. After being pressurized and heated by the screw compressor 6, it enters the liquid separation tank 3. To maximize the heat exchange efficiency of the vapor at the outlet of the screw compressor 6, a part of the liquid phase at the bottom of the liquid separation tank 3 is always used as the liquid injection at the inlet of the screw compressor 6 to ensure that the vapor at the outlet of the screw compressor 6 is in two states of saturation and superheat, so as to achieve the maximum efficiency of latent heat and sensible heat exchange when the vapor at the outlet of the screw compressor 6 exchanges heat with the reboiler 4 at the bottom of the ethanol rectification column. The liquid phase from the liquid separation tank 3 to the liquid injection at the compression inlet of the screw compressor 6 is linked and controlled with the outlet temperature of the screw compressor 6, so as to achieve automatic liquid injection control. When the liquid level of the liquid separation tank 3 is relatively low, the liquid phase can also be directly supplemented to the liquid separation tank 3 through the ethanol product external feeding line 16 to avoid the failure of liquid injection caused by insufficient liquid phase in the liquid separation tank 3; at the same time, to prevent the liquid level of the liquid separation tank 3 from being too high, the liquid separation tank 3 is provided with a liquid phase outlet, which is sent to the reflux tank 5 through a regulating valve after being linked with the liquid level of the liquid separation tank 3 and used as the liquid phase reflux to the ethanol rectification separation column 1.

[0037] The rectification system of the ethanol rectification separation column 1 is a guarantee system for providing heat source for the ethanol rectification separation column 1. To maximize the heat utilization, the liquid phase flowing back to the top of the ethanol rectification separation column 1 for reflux operation from the reflux tank 5 first enters the top flash tank 2, and part of the vapor is flashed out and continues to enter the screw compressor 6 system, thus realizing the sufficient supply of the vapor at the inlet of the screw compressor 6 system. At the same time, the liquid temperature of the liquid phase in the top flash tank 2 is reduced due to flashing, and it flows into the ethanol rectification separation column 1 by gravity to realize product reflux and improve the purity of the vapor ethanol component at the top of the column.

[0038] The present invention adopts a brand-new heat pump rectification system, replacing the traditional multi-effect rectification system, saving the consumption of the overhead cooling circulating water in the multi-effect rectification, and making full use of the high-efficiency heat exchange of the latent heat and sensible heat of the heat pump for pressurizing the overhead vapor, thus greatly reducing the operating energy consumption of the rectification system, and the comprehensive reduction of its energy consumption reaches 34.14%; in addition, the system adopts interlocking controls such as temperature, pressure, and liquid level, with a high degree of automation control, saving on-site operators. It can be reduced from 5 people / shift in the traditional multi-effect rectification to 3 people / shift, realizing the reduction of personnel through automation, and at the same time reducing the requirements for the professional quality and comprehensive level of the operators in the rectification system control, and greatly reducing the system fluctuations caused by misoperations; in addition, this system reduces the investment and construction of the traditional multi-effect rectification tower system, and the total investment of the system is reduced by about 20%.

[0039] It should be noted that the above embodiments all belong to the same utility model concept. The descriptions of the embodiments have their own focuses. For the parts not described in detail in individual embodiments, reference can be made to the descriptions in other embodiments.

[0040] The above-described embodiments merely represent the implementation modes of the present utility model. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all fall within the protection scope of the present utility model. Therefore, the protection scope of the present utility model patent shall be subject to the appended claims.

Claims

1. An energy-saving distillation system for extracting xanthan gum ethanol solvent, comprising an ethanol distillation separation tower (1), an ethanol distillation tower bottom reboiler (4) and a control end, characterized in that: The ethanol distillation separation tower (1) is connected to a preheating heat exchanger (7) and a waste heat exchanger (8) in sequence. The top distillate component of the ethanol distillation separation tower (1) is connected to a compression system via a top distillate pipeline (11), and is compressed by the compression system and sent to a bottom reboiler (4) of the ethanol distillation tower.

2. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 1, characterized in that: A top flash tank (2) is arranged at the top of the ethanol distillation separation tower (1), and the gas phase of the flashed portion of the top flash tank (2) is sent to a compression system, and the liquid phase of the top flash tank (2) is sent back to the ethanol distillation separation tower (1) through a circulating reflux system.

3. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 2, characterized in that: The circulating reflux system comprises an ethanol distillation tower reflux pump, a product delivery pump (9) and a reflux tank (5); the liquid phase of the top flash tank (2) is sent to the reflux tank (5) through the ethanol distillation tower reflux pump and the product delivery pump (9); the liquid phase in the reflux tank (5) enters the reboiler (4) at the bottom of the ethanol distillation tower by gravity for circulation.

4. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 2, characterized in that: The compression system comprises a screw compressor (6) and a liquid separator (3); the output end of the screw compressor (6) is connected to the liquid separator (3) via a transmission pipeline (12); the liquid separator (3) is connected to a reboiler (4) at the bottom of an ethanol distillation tower via a reboiler transmission pipeline (15); and the input end of the screw compressor (6) is connected to a distillation pipeline (11) at the top of the tower.

5. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 4, characterized in that: The liquid phase at the bottom of the liquid separation tank (3) is connected to the tower top distillation pipeline (11) through a liquid supply pipeline (14) to transport the spray liquid to the screw compressor (6). A temperature sensor is provided on the transmission pipeline (12), and a regulating valve is provided on the liquid supply pipeline (14). The control end controls the opening of the regulating valve through an electrical signal from the temperature sensor to achieve interlocking control.

6. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 4, characterized in that: The tower top distillation pipeline (11) is connected to an external feed line (16) for supplying ethanol to the input end of the screw compressor (6). The liquid phase outlet of the liquid separation tank (3) is also provided with a reflux pipeline (17) connected to the reflux tank (5) and is sent back to the ethanol distillation separation tower (1) via the reflux tank (5). The external feed line (16) and the reflux pipeline (17) are both provided with regulating valves. The liquid separation tank (3) is equipped with a liquid level sensor. The control end controls the opening of the regulating valve through an electrical signal of the liquid level sensor to achieve interlocking control.

7. An energy-saving distillation system for extracting xanthan gum ethanol solvent according to claim 4, characterized in that: The reboiler delivery pipeline (15) is connected to the tower top distillation pipeline (11) via a constant pressure pipeline (18), a regulating valve is provided on the constant pressure pipeline (18), and a pressure sensor is provided on the tower top distillation pipeline (11). The control end controls the opening of the regulating valve through an electrical signal from the pressure sensor, thereby realizing interlocking control.

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