Waste triethylene glycol purifying and recycling device

Abstract

A waste triethylene glycol purification and recycling device relates to the technical field of triethylene glycol purification devices and comprises a triethylene glycol vacuum evaporation tank, a primary condenser, a secondary condenser, a condensation storage tank, a gas-liquid separation tank and a vacuum pump, a steam outlet pipeline A is arranged at the upper end of the triethylene glycol vacuum evaporation tank and communicated with an inlet of the primary condenser, and a steam outlet pipeline B is arranged at the lower end of the steam outlet pipeline A; triethylene glycol steam is condensed into liquid through the first-stage condenser, an outlet of the first-stage condenser is communicated with the condensation storage tank, a steam outlet pipeline B is arranged on the upper portion of the condensation storage tank and communicated with an inlet of the second-stage condenser, and gaseous triethylene glycol steam is condensed into liquid through the second-stage condenser. An outlet of the secondary condenser is communicated with a gas-liquid separation tank; the upper part of the gas-liquid separation tank is communicated with a vacuum pump; the vacuum degree of the triethylene glycol vacuum evaporation tank is 4KPa, and under the vacuum degree, the boiling point of triethylene glycol is lower than 200 DEG C and lower than the theoretical decomposition temperature of 208 DEG C, so that purer triethylene glycol can be obtained and reaches the recycling standard.

Description

Technical Field

[0001] This utility model belongs to the technical field of triethylene glycol purification equipment, and in particular relates to a waste triethylene glycol purification and reuse device. Background Technology

[0002] From underground extraction to market sale, natural gas undergoes a separation and dehydration process. Triethylene glycol (TED) dehydration is a mature, reliable, and widely used technology. TED has a high boiling point, good hygroscopicity, and stable chemical properties, and operates using a water absorption and regeneration cycle. However, during the circulating dehydration process, oxides generated by the high-temperature fire-tube reboiler, dissolved heavy hydrocarbon impurities from the natural gas, and TED decomposition products such as diethylene glycol and ethylene glycol contaminate the TED solution, reducing its purity and dehydration efficiency, resulting in a large amount of waste TED solution that needs to be replaced with new TED during annual maintenance. This large amount of waste TED not only wastes resources but also leads to significant stockpiling in storage. Furthermore, improper disposal of waste TED can harm the environment. Therefore, effective technical measures are urgently needed to achieve the recycling and reuse of this large amount of waste TED.

[0003] Because the boiling points of diethylene glycol, ethylene glycol, water, and higher hydrocarbons in waste triethylene glycol liquid are all much lower than the boiling point of triethylene glycol (at normal pressure, the boiling point of diethylene glycol is 245℃, ethylene glycol is 135℃, water is 100℃, and the boiling points of higher hydrocarbons (C4, C5, C5+) are below 100℃, while the boiling point of triethylene glycol at normal pressure is 289.5℃), current technology involves heating the waste triethylene glycol liquid to a temperature below the boiling point of triethylene glycol at normal pressure, then evaporating the mixture to obtain triethylene glycol liquid. However, the triethylene glycol liquid obtained by this existing method still contains trace amounts of other large-molecule organic matter, and its purity does not meet the standards for reuse. Utility Model Content

[0004] To address the problem of recycling and reusing large quantities of waste triethylene glycol, this invention provides a device for purifying and reusing waste triethylene glycol. This invention can obtain high-purity triethylene glycol through vacuum distillation.

[0005] The technical solution provided by this utility model is: a device for purifying and reusing waste triethylene glycol, comprising a triethylene glycol vacuum evaporator, a primary condenser, a condensate storage tank, a secondary condenser, a gas-liquid separator, and a vacuum pump. The upper end of the triethylene glycol vacuum evaporator is provided with a steam outlet pipe A, which is connected to the inlet of the primary condenser. The primary condenser condenses the triethylene glycol vapor into liquid. The outlet of the primary condenser is connected to the condensate storage tank, where the condensed liquid is stored. The upper part of the condensate storage tank is provided with a steam outlet pipe B, which is connected to the inlet of the secondary condenser. The secondary condenser condenses the still gaseous triethylene glycol vapor into liquid. The outlet of the secondary condenser is connected to the gas-liquid separator, where the liquid after secondary condensation is stored. The upper part of the gas-liquid separator is connected to the vacuum pump, which, on the one hand, extracts unliquefied gas, and on the other hand, ensures that the entire device is under a reasonable vacuum state. The triethylene glycol vacuum evaporator is welded with... A horizontal partition divides the triethylene glycol vacuum evaporator into an evaporation section and a storage section. The evaporation section is located above the storage section and includes a heat exchange tube bundle. Both ends of the heat exchange tube bundle are fixed with tube bundle fixing partitions, which are welded to the tank body of the triethylene glycol vacuum evaporator. A hot oil inlet and a hot oil outlet are respectively provided on the tank body between the two tube bundle fixing partitions. Hot oil flows through the outside of the heat exchange tube bundle, raising the temperature of the triethylene glycol inside the heat exchange tube bundle to the evaporation temperature. The lower part of the horizontal partition... A suction pipe is welded to the end face, extending into the bottom of the triethylene glycol vacuum evaporator. The liquid in the storage section is drawn into the heat exchange tube bundle through the suction pipe. An air inlet pipe is connected to the upper part of the storage section, and a flow control valve is installed on the air inlet pipe. The flow control valve is used to adjust the amount of gas entering the storage section, so that the gas pressure in the storage section is greater than that in the evaporation section. Under the action of the gas pressure, the liquid in the storage section is forced into the heat exchange tube bundle through the suction pipe, so that the liquid in the heat exchange tube bundle flows continuously from bottom to top.

[0006] A further technical solution is: the space between the diaphragm and the tube bundle fixing diaphragm at the lower end of the heat exchange tube bundle is called the liquid distribution space. The lower end of the heat exchange tube bundle extends into the liquid distribution space. The liquid distribution chamber enables each heat exchange tube of the heat exchange tube bundle to absorb liquid evenly.

[0007] A further technical solution is to install an insulation tank on the outside of the triethylene glycol vacuum evaporator to reduce temperature loss.

[0008] A further technical solution is: a gas-liquid separation membrane is provided at the upper end of the gas-liquid separation tank, and the gas-liquid separation membrane filters the liquid before it enters the vacuum pump.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0010] 1. At a vacuum of 4 kPa, the boiling point of triethylene glycol is below 200°C, which is below the theoretical decomposition temperature of 208°C. Evaporating and purifying triethylene glycol under this vacuum can yield a purer triethylene glycol, making it meet the standards for recycling.

[0011] 2. The triethylene glycol vacuum evaporator can maintain a certain degree of vacuum, maximize the liquid storage capacity, and achieve partial endothermic evaporation, which reduces heat consumption and increases the evaporation rate. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] Figure 2 This is a schematic diagram of the triethylene glycol vacuum evaporator in this utility model.

[0014] In the diagram: 1. Insulated container; 2. Triethylene glycol vacuum evaporator; 3. Steam outlet pipe A; 4. First-stage condenser; 5. Condensate storage tank; 6. Steam outlet pipe B; 7. Second-stage condenser; 8. Gas-liquid separator; 9. Gas-liquid separation membrane; 10. Vacuum pump; 2001. Tube bundle fixing baffle; 2002. Hot oil outlet; 2003. Heat exchange tube bundle; 2004. Flow control valve; 2005. Inlet pipe; 2006. Suction pipe; 2007. Horizontal baffle; 2008. Liquid distribution chamber; 2009. Hot oil inlet. Detailed Implementation

[0015] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0016] Under normal pressure, diethylene glycol has a boiling point of 245°C, ethylene glycol 135°C, water 100°C, and higher carbon hydrocarbons (C4, C5, C5+) have boiling points below 100°C, while triethylene glycol has a boiling point of 289.5°C under normal pressure. First, under normal pressure, a mixture of waste triethylene glycol is heated to a temperature below the boiling point of triethylene glycol, and then evaporated to obtain preliminarily purified triethylene glycol liquid. This apparatus is used to distill the preliminarily purified triethylene glycol to obtain high-purity triethylene glycol. The distillation apparatus provided in this embodiment is as follows.

[0017] like Figure 1 and Figure 2 As shown, this embodiment includes a triethylene glycol vacuum evaporator 2, a primary condenser 4, a condensate storage tank 5, a secondary condenser 7, a gas-liquid separator 8, and a vacuum pump 10.

[0018] The triethylene glycol vacuum evaporator 2 is equipped with a steam outlet pipe A3 at its upper end, which is connected to the inlet of the primary condenser 4. The primary condenser 4 condenses the triethylene glycol vapor into liquid. The outlet of the primary condenser 4 is connected to a condensate storage tank 5, where the condensed liquid is stored. A steam outlet pipe B6 is located at the upper part of the condensate storage tank 5, which is connected to the inlet of the secondary condenser 7. The secondary condenser 7 condenses the still gaseous triethylene glycol vapor into liquid. The outlet of the secondary condenser 7 is connected to a gas-liquid separator 8, where the liquid after secondary condensation is stored. The upper part of the gas-liquid separator 8 is connected to a vacuum pump 10. The vacuum pump 10 removes unliquefied gas and ensures the entire apparatus is under a proper vacuum. The vacuum level of the entire apparatus is maintained at 4 kPa. At a vacuum level of 4 kPa, the boiling point of triethylene glycol is below 200°C, which is below the theoretical decomposition temperature of 208°C. By lowering the evaporation temperature of triethylene glycol, heat energy consumption is reduced, and the decomposition of triethylene glycol is avoided. Therefore, triethylene glycol can be purified to a purer state under this vacuum.

[0019] The triethylene glycol vacuum evaporator 2 is equipped with a horizontal partition 2007, which divides the triethylene glycol vacuum evaporator 2 into an evaporation section and a storage section. The evaporation section is located above the storage section. The evaporation section includes a heat exchange tube bundle 2003. Both ends of the heat exchange tube bundle 2003 are fixed with tube bundle fixing partitions 2001. The tube bundle fixing partitions 2001 are welded to the tank body of the triethylene glycol vacuum evaporator 2. The tank body of the triethylene glycol vacuum evaporator 2 between the two tube bundle fixing partitions 2001 is respectively provided with a hot oil inlet 2009 and a hot oil outlet 2002. The hot oil temperature is 200°C. The hot oil flows through the outside of the heat exchange tube bundle 2003, raising the temperature of the triethylene glycol in the heat exchange tube bundle 2003 to the evaporation temperature of 200°C. A suction pipe 2006 is welded to the lower end face of the partition plate 2007. The suction pipe 2006 extends into the bottom of the triethylene glycol vacuum evaporator 2. The liquid in the storage section is drawn into the heat exchange tube bundle 2003 through the suction pipe 2006. An air inlet pipe 2005 is connected to the upper part of the storage section. An adjustment valve 2004 is installed on the air inlet pipe 2005. The air volume entering the storage section is adjusted by the adjustment valve 2004, so that the air pressure in the storage section is greater than the air pressure in the evaporation section. Under the action of air pressure, the liquid in the storage section is forced into the heat exchange tube bundle 2003 through the suction pipe 2006. Thus, the liquid in the heat exchange tube bundle 2003 flows continuously from bottom to top. After the liquid in the heat exchange tube bundle 2003 evaporates, liquid will continue to enter the heat exchange tube bundle 2003 from bottom to top.

[0020] The triethylene glycol vacuum evaporator 2 in this application can store a large amount of triethylene glycol liquid and also achieve partial heat absorption and evaporation. The hot oil only transfers heat to the triethylene glycol in the heat exchange tube, ensuring the evaporation rate and reducing heat consumption.

[0021] The space between the diaphragm 2007 and the tube bundle fixing diaphragm 2001 at the lower end of the heat exchange tube bundle 2003 is called the liquid distribution space. The lower end of the heat exchange tube bundle 2003 extends into the liquid distribution space. The liquid distribution chamber 2008 enables each heat exchange tube of the heat exchange tube bundle 2003 to absorb liquid evenly.

[0022] The outside of the triethylene glycol vacuum evaporator 2 is equipped with an insulation tank 1 to reduce temperature loss.

[0023] The gas-liquid separator 8 is provided with a gas-liquid separation membrane 9 at its upper end. The residual gas is filtered and absorbed by the gas-liquid separation membrane 9, and then discharged through the vacuum pump 10.

[0024] Economic impact: The price of each ton of new triethylene glycol is 14,850 yuan. A company produces approximately 90 tons of waste triethylene glycol annually. In addition, the waste triethylene glycol produced each year cannot be directly discharged according to environmental protection requirements. The annual environmental treatment cost is calculated at 300,000 yuan. Therefore, the comprehensive usage price of each ton of triethylene glycol is 18,150 yuan.

[0025] A single unit capable of distilling and purifying 3 tons of triethylene glycol per day costs 1.8 million yuan. This includes depreciation of 1200 yuan / ton, equipment maintenance of 200 yuan / ton, fuel costs of 500 yuan / ton, labor costs of 1400 yuan / ton, site costs of 900 yuan / ton, residue treatment costs of 500 yuan / ton, transportation costs of 200 yuan / ton, management costs of 200 yuan / ton, environmental protection costs of 600 yuan / ton, taxes of 800 yuan / ton, insurance costs of 300 yuan / ton, and a profit of 1000 yuan / ton. The total cost of the purified triethylene glycol is 7800 yuan / ton. Compared to new triethylene glycol, this represents a saving of 10350 yuan per ton, demonstrating significant economic benefits. Other small amounts of large-molecule organic matter and impurities are adsorbed and dissolved by surfactant solution, transforming into a pre-fluid for carbon dioxide composite huff and puff. Combined with on-site composite huff and puff operations, this effectively improves the success rate of oil well treatments and achieves harmless disposal. Furthermore, no secondary environmental pollution was generated during the entire purification process, and the residue after triethylene glycol purification was further developed and utilized, maximizing the economic and social benefits of waste triethylene glycol.

Claims

1. A device for purification and reuse of waste triethylene glycol, characterized by: The device comprises a triethylene glycol vacuum evaporation tank (2), a first condenser (4), a condensing tank (5), a second condenser (7), a gas-liquid separation tank (8) and a vacuum pump (10), the upper end of the triethylene glycol vacuum evaporation tank (2) is provided with a steam outlet pipeline A (3), the steam outlet pipeline A (3) is communicated with the inlet of the first condenser (4), the triethylene glycol steam is condensed into liquid through the first condenser (4), the outlet of the first condenser (4) is communicated with the condensing tank (5), the upper part of the condensing tank (5) is provided with a steam outlet pipeline B (6), the steam outlet pipeline B (6) is communicated with the inlet of the second condenser (7), the triethylene glycol steam still in gaseous state is condensed into liquid through the second condenser (7), the outlet of the second condenser (7) is communicated with the gas-liquid separation tank (8), the upper part of the gas-liquid separation tank (8) is communicated with the vacuum pump (10); the triethylene glycol vacuum evaporation tank (2) is welded with a transverse partition plate (2007), the transverse partition plate (2007) divides the triethylene glycol vacuum evaporation tank (2) into an evaporation section and a storage section, the evaporation section comprises a heat exchange pipe bundle (2003), the two ends of the heat exchange pipe bundle (2003) are fixedly connected with pipe bundle fixed partition plates (2001), the pipe bundle fixed partition plates (2001) are welded with the tank body of the triethylene glycol vacuum evaporation tank (2), the lower end surface of the transverse partition plate (2007) is welded with a liquid suction pipe (2006), the liquid suction pipe (2006) extends into the bottom of the triethylene glycol vacuum evaporation tank (2), the upper part of the storage section is connected with an air inlet pipe (2005), the air inlet pipe (2005) is provided with a flow regulating valve (2004).

2. The device for purifying and recycling waste triethylene glycol according to claim 1, characterized in that: The space between the transverse partition plate (2007) and the pipe bundle fixed partition plates (2001) at the lower end of the heat exchange pipe bundle (2003) is called a liquid separation space, the lower end of the heat exchange pipe bundle (2003) extends into the liquid separation space.

3. The device for purifying and recycling waste triethylene glycol according to claim 1, characterized in that: The outer side of the triethylene glycol vacuum evaporation tank (2) is provided with a heat preservation barrel (1).

4. The device for purifying and recycling waste triethylene glycol according to claim 1, characterized in that: The upper end of the gas-liquid separation tank (8) is provided with a gas-liquid separation membrane (9), the gas-liquid separation membrane (9) is filtered and then enters the vacuum pump (10).

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