KR100722942B1 - Ethanolamine recovery method with physicochemical process - Google Patents

Abstract

The present invention relates to a method for recovering ethanolamine used in nuclear and thermal power plants, more specifically, the wastewater introduced is an ethanolamine capture concentration step using a cation exchange resin; A first distillation step of heating the wastewater in which the ethanolamine is concentrated by the cation exchange resin to 60 to 100 ° C .; The second distillation step of heating the wastewater passed through the first distillation step to 100 ~ 200 ℃; and recovering the expensive ethanolamine from the wastewater containing ethanol amine as the main configuration.

Ethanolamine, Nuclear Wastewater Treatment, Ion Exchange, Distillation, Cooling

Description

Ethanolamine recovery by physicochemical process {ETHANOLAMINE RECOVERY METHOD WITH PHYSICOCHEMICAL PROCESS}

1 is a block diagram showing a process for recovering ethanolamine wastewater by a complex process according to the present invention

2 is a schematic diagram showing a system to which an embodiment of the present invention is applied.

Explanation of the main symbols in the drawings

1: ion exchange resin tower 2: cation exchange resin 3: caustic soda tank

4: caustic soda solution 5: air 6: adsorption tower

7: sorbent 8: evaporation tower 9: heater

10: cooling unit 11: recovery tank

The present invention comprises an ethanolamine capture concentration step using a cation exchange resin for wastewater containing ethanolamine used in nuclear and thermal power plants; A first distillation step of heating the wastewater in which the ethanolamine is concentrated by the cation exchange resin to 60 to 100 ° C .; It relates to a method for recovering expensive ethanolamine from the wastewater introduced through the second distillation step of heating the wastewater passed through the first distillation step to 100 ~ 200 ℃.

Nuclear and thermal power plants use water as an energy transfer medium to obtain electrical energy from nuclear energy or fossil fuels. In general, the water / steam circulation system in a power plant vaporizes water, rotates a turbine to produce electricity, and then produces steam. Recycle again by condensing with water.

At this time, since various components in the condensed water may be damaged by corrosion, chemicals such as pH control agent and chemical potential control agent are injected. This is because corrosion of various metals can be suppressed electrochemically.

Ion exchange resin towers are installed in the water / steam circulation system of nuclear and thermal power plants to remove trace impurities as well as chemicals injected for corrosion inhibition. Repeat the process of removing and reinjecting from the outside.

In the past, since the chemical was used as a volatile substance and released into the atmosphere during processing, it was possible to treat heavy metals discharged from the power plant by a simple physicochemical process, but the ethanolamine as a pH control agent is now adopted to reduce COD and total nitrogen components. The contained wastewater discharged in large quantities can no longer meet the discharge limit.

The ethanolamine has a chemical structure of NH ₂ CH ₂ CH ₂ OH, and consists of carbon, hydrogen, oxygen, and nitrogen, and when present in wastewater, the biological oxygen demand, biochemical oxygen demand, and nitrogen concentration specified in the environmental emission allowance standard. As an expensive substance causing an increase, it is urgent to treat this ethanolamine.

Therefore, there is a demand for a technology capable of treating and discharging ethanolamine wastewater discharged from nuclear and thermal power plants below environmental standards.

In order to solve the above problems, the present invention not only prevents ethanolamine from being discharged from wastewater of ethanolamine discharged from nuclear and thermal power plants, but also recovers and reuses expensive ethanolamine to increase industrial use value. An object of the present invention is to provide a method for recovering ethanolamine.

In order to achieve the above object, the present invention passes the introduced waste water through the ion exchange resin tower (1) filled with the cation exchange resin (2), to capture and concentrate the ethanolamine through the cation exchange resin (2) Thereafter, the ethanolamine capture concentration step of transferring the waste water in which the ethanolamine is concentrated in the evaporation tower (8);

The gas generated by first heating the wastewater introduced into the evaporation tower 8 at 60 to 100 ° C. is passed through an adsorption tower 6 filled with zeolite to adsorb ethanolamine, and the vapor from which the ethanolamine is removed is air. A first distillation step of discharging to the inside;

Steam and ethanolamine generated by the second heating to 100 ~ 200 ℃ to the wastewater passed through the first distillation step to the cooling tower 10, the secondary condensing at a temperature of 10 ~ 25 ℃ in the cooling tower (10) The main structure is a method for recovering ethanolamine in which ethanolamine is recovered through a distillation step.

Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a flow chart illustrating the ethanolamine recovery process of the present invention, waste water is passed through the cation exchange resin is trapped ethanolamine, the caustic soda and air is injected into the cation exchange resin trapped by the ethanol amine eluted ethanolamine After concentrating the wastewater, the ethanolamine capture concentration step of transferring the wastewater to the evaporation tower (S10),

The first distillation step (S20) of adsorbing ethanolamine and the vapor from which the ethanolamine is removed is adsorbed by passing the gas generated by first heating the wastewater introduced into the evaporation tower through a zeolite-filled adsorption tower. Wow,

Secondary heating of the wastewater passed through the first distillation step is transferred to a cooling tower, and is treated through a second distillation step (S30) condensing in the cooling tower to condense ethanolamine.

Figure 2 shows a schematic diagram of a process for recovering the ethanolamine of the present invention, the ion exchange resin tower (1) through which the waste water is passed, and the cation exchange resin (2) is filled inside the ion exchange resin tower (1) By injecting caustic soda solution 4 and air 5 introduced from the caustic soda tank 3 into the ion exchange resin tower 1, the cation exchange resin 2 is stirred to concentrate ethanolamine. Ethanolamine capture concentration step;

The wastewater containing the concentrated ethanolamine is transferred to the evaporation tower (8), and the wastewater introduced into the evaporation tower (8) is first heated to 60 to 100 ° C using a heating device (9) to adsorb the gas generated. Passing through the adsorption tower (6) filled with (7), adsorbing ethanolamine and discharging the ethanolamine-removed vapor into the atmosphere;

The waste water from which the foreign matter is removed by the first heating is secondarily heated to 100 to 200 ° C., and the vapor generated by the second heating is transferred to the cooling tower 10, and condensed at a temperature of 10 to 25 ° C. in the cooling tower 10 to recover a recovery tank ( It is composed of; secondary distillation step to recover the ethanolamine in 11).

In the ethanolamine capture concentration step, the ethanolamine of the wastewater is captured through the cation exchange resin (2) filled in the ion exchange resin tower (1) made of a high molecular material or a metal such as stainless steel, which does not generate corrosion. As the cation exchange resin 2, a sulfonic acid type based on a divinylene-styrene copolymer is used. When the ion exchange capacity of the cation exchange resin 2 is lost, a caustic soda solution of the caustic soda tank 3 is used. (4) and air (5) are injected to stir the cation exchange resin (2).

In addition, the ethanolamine capture concentration step refers to a process in which regeneration wastewater is produced in the ion exchange resin tower (1), and the caustic soda solution (4) and air (5) of the caustic soda tank (3) are transferred to the ion exchange resin layer. Obtained by passing. In this process, the concentration of ethanolamine wastewater initially introduced is concentrated to about 1 / 10,000 to 1 / 20,000, and the wastewater is reduced and its volume is reduced.

At one side of the ion exchange resin tower (1), an adsorption tower (6) is installed to block ethanolamine from being released into the atmosphere, and an adsorbent (7) is filled in the adsorption tower (6), and the adsorbent (7) As the zeolite is used, since the zeolite can physically or chemically bind a chemical substance to the microcavity existing within the crystal structure, the zeolite is adsorbed while passing gaseous water and ethanolamine together with air.

As described above, the weight loss wastewater collected through the ethanolamine capture concentration step is transferred to the evaporation tower (8), which evaporates the regeneration wastewater of the ion exchange resin tower (1) in the first and second stages. The evaporation tower (8) does not generate corrosion in the strong base and is made of stainless steel or aluminum material having excellent heat transfer.

The first distillation step is heated to 60 ~ 100 ℃ and the generated steam and a small amount of ethanolamine is passed through the adsorption tower (6) to release to the atmosphere, the temperature of the first distillation step is 60 ~ 100 ℃. This is because when the water containing the ethanolamine is heated gas and ethanolamine becomes a gas, since the boiling temperature of the water is 100 ℃, ethanol amine 170 ℃, water and a very small amount of ethanol amine is evaporated up to 100 ℃. Therefore, the temperature of the first distillation step is preferably 60 ~ 100 ℃.

In addition, the gas of water and ethanolamine evaporated in the first distillation step is adsorbed by the adsorbent (7) filled in the adsorption tower (6) between the evaporation tower (8) and the cooling tower (9) to release the ethanolamine into the atmosphere. The ethanolamine adsorbed adsorbent (7) is immersed in pure water to regenerate the adsorbent (7). The adsorbent (7) is a gaseous water and ethanolamine in a microcavity that is internally crystalline. Zeolites capable of adsorbing are used.

The second distillation step is heated to 100 ~ 200 ℃, because when heated to more than 100 ℃ no water and no ethanolamine is evaporated. The ethanolamine generated at this time is transferred to the cooling tower 10, and after the evaporation is finished, the inside is washed with pure water. The inside of the evaporation tower (8) is made of carbon and filled with activated carbon having a microcavity therein, and organic materials and solids present in the regeneration waste liquid may be carried over to prevent inclusion in the gas phase.

Carryover refers to a phenomenon in which, when boiling water in which organic or inorganic substances which are not volatile are boiled, water flows into the atmosphere as steam, and organic or inorganic matters remain in water because they do not boil, but fly into the atmosphere together with steam or foam.

The cooling tower 10 serves to condense the vapor and gaseous ethanolamine from the evaporation tower (8), when the cooling temperature is less than 10 ℃ ethanol amine is difficult to recover because the freezing point of 10 ℃, Since the freezing point of tap water, ground water and sea water is generally 25 ° C. or less, the cooling temperature of the cooling tower 10 is preferably 10 to 25 ° C.

In addition, the cooling tower 10 is formed of a metal material such as iron does not contain corrosion in the strong base, and does not contain a copper component excellent in heat transfer, air, water, refrigerant as a heat removal source of the cooling tower 10 Can be used.

The ethanolamine condensed through the cooling tower 10 is collected in the recovery tank 11, the ethanolamine aqueous solution is recovered. The recovered ethanolamine aqueous solution is injected into an evaporation tower and treated.

As described above, according to the present invention, the wastewater containing ethanolamine through the ethanolamine capture concentration step, the first distillation step and the second distillation step satisfies the biochemical oxygen demand and nitrogen content, which is an environmental emission standard, and is discharged at the same time as the expensive ethanol. The amine is recovered.

As described above, according to the present invention, by treating ethanolamine, a source of biochemical oxygen demand and total nitrogen, in the wastewater of nuclear and thermal power plants during regeneration of the ion exchange resin at the time of generation, it does not cause an increase in load of the existing wastewater treatment plant. Not only that, but it also eliminates the need for facility improvements.

In addition, it is possible to improve the economics of the power plant by recovering and reusing ethanolamine continuously injected to the water / steam circulation system of nuclear and thermal power plants to prevent corrosion.

Claims (4)

The wastewater introduced is passed through an ion exchange resin tower (1) filled with a cation exchange resin (2) to capture and concentrate the ethanolamine through the cation exchange resin (2), and then evaporate the wastewater containing the concentrated ethanolamine. Ethanolamine capture concentration step (S10) to be transferred to the tower (8); The steam generated by first heating the wastewater introduced into the evaporation tower 8 at 60 to 100 ° C. is passed through the adsorption tower 6 filled with zeolite to adsorb ethanolamine, and the vapor from which the ethanolamine is removed is air. A first distillation step (S20) to be released into the; The steam generated by the second heating to 100 ~ 200 ℃ in the waste water from which the foreign matter is removed through the first distillation step is transferred to the cooling tower 10, the cooling treatment to 10 ~ 25 ℃ temperature in the cooling tower 10 Second distillation step (S30); Ethanolamine recovery method characterized in that the ethanolamine is recovered. The method of claim 1, The ethanolamine capture concentration step (S10) captures wastewater containing ethanolamine with a cation exchange resin (2), and then caustic injected from the caustic soda tank (3) provided on one side of the ion exchange resin tower (1). Elution using soda (4) to reduce the volume of the ethanolamine waste water, characterized in that for recovering ethanolamine. The method of claim 1, The ethanolamine released in the gas phase in the ethanolamine capture concentration step is adsorbed by the zeolite packed in the adsorption tower 6 provided on one side of the ion exchange resin tower 1 to block the release of ethanolamine into the atmosphere, and the ethanolamine A method for recovering ethanolamine, further comprising the step of regenerating the zeolite by immersing the adsorbed zeolite in pure water. The method of claim 1, The evaporation tower (8) is a method for recovering ethanolamine, characterized in that the activated carbon is filled in order to prevent the organic matter and solids present in the waste water is carried over to the gas phase.

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