The method of disposal of waste automotive antifreeze

 

(57) Abstract:

The invention relates to the field of environmental protection from pollution by toxic substances used automotive antifreeze. The method of disposal of waste automotive antifreeze includes sucks raw materials from oil and sludge, water distillation, and the distillation of ethylene glycol under vacuum, and before entering the distillation column antifreeze is alkalinized to pH 11,0-13,0, the distillation of water is performed at a residual pressure of 12 to 24 kPa, the temperature in the cube 76-92oWith, in the upper part of the column 45-60oWith, and the distillation of ethylene glycol is at a residual pressure of 0.7 to 2.5 kPa, at a temperature of cube 90-150oWith, in the upper part of the column 75-105oC. is Reached, increasing the degree of separation and the quality of the glycol. table 2.

The invention relates to the field of environmental protection from pollution by toxic substances used automotive antifreeze.

Currently, a large part of the car Park is used as a coolant for engines antifreeze type Antifreeze And containing not less than 50 wt.% toxic diatomic alcohol, ethylene glycol.

Waste antifreeze ascontrol the Col is quite an expensive product, a tonne of which is spent not less than 3 tons of crude oil. Thus, utilization of ethylene glycol from spent antifreeze important from an environmental and an economic point of view.

It is known [Kogan D. B., Friedman C. M., Kafarov centuries Equilibrium between liquid and vapour. M. - L.: Nauka, 1966, T. 1, S. 283-285] that water and ethylene glycol does not form azeotropic mixtures, and the boiling temperature of these fluids differ significantly (100 and 197oC, respectively). We recommend that you separate a mixture of water and ethylene glycol by distillation at normal pressure, i.e., the most simple and cheap way. Our experiments showed that for used automotive antifreeze this way is unacceptable, because it is a mixture of ethylene glycol, the products of its partial decomposition, additive, water that has oil, particles and corrosion products, including ions of lead, copper, tin, zinc. From such a mixture to drive off pure ethylene glycol at atmospheric pressure is impossible. The result is a product of poor quality, unsuitable for placing on the market or processing in place in other types of products.

The closest analogue is the following way [Zhuravlev, A. B., ZAR is botanova antifreeze"]. Before the distillation of ethylene glycol from spent antifreeze methods of defending separated solids and oils. The Stripping of water from the spent antifreeze (water 99.99% purity) is carried out at a residual pressure of 34 kPa, the temperature in the cube - 130oWith, in the upper part of the column - 70oFrom the distillation of ethylene glycol is at a residual pressure of 2.7 to 6.7 kPa, the temperature in the cube - not more than 170oWith, in the upper part of the column is 105-125oC. complete selection of glycol - 93 to 95 wt.%.

This method has the following disadvantages.

1. Insufficient degree of extraction of the spent glycol 93-95%.

2. Unstable quality warded off ethylene glycol. Characteristics of spent antifreeze change randomly. Found that more than 50% of the individual samples when they justify the quality warded off antifreeze does not meet GOST 19710-83, in particular, in appearance - the presence of colored impurities, and acidic character.

As a result, the ethylene glycol may not be implemented on the market.

An object of the invention is to provide a method of recycling that can improve the discharge of glycol and improve its quality.

Alkalinization of the spent antifreeze below pH=11,0 insufficient binds organic impurities acidic nature, they are distilled together with ethylene glycol and partially with water and degrade the quality of the glycol. The alkalization above pH=13 is impractical due to excess alkali.

Distillation of water at a residual pressure of 12-24 kPa allows to obtain a stable clear water free from organics, including ethylene glycol. Because of this water can be used in the production of technical desalted (e.g. for feeding steam boilers) or safely discharged into the sewer (ethylene glycol less than 1 mg/l, i.e., less than maximum allowable concentration). At a higher residual pressure of deteriorating water quality on organic primesource economically, as increased demands on sealing equipment.

The temperature in the cube supported within 76-92oC. When the temperature rises above 92oWith the intensive boiling of the liquid in the cube, the pressure increases, the process of distillation is difficult. In the upper part of the column temperature is maintained at 45-60oWith, in which there is a steady process of distillation of water.

Distillation of ethylene glycol was carried out at a pressure of 0.7 to 2.5 kPa and the temperature of the cube 90-150oC. At higher pressures and temperatures deteriorates the quality organochloro of ethylene glycol. At pressures less than 0.7 kPa and temperatures of the cube 90oWith slowing the process of distillation, and the yield of ethylene glycol is not increased. In the upper part of the column temperature is maintained at 75-105oWith, in which there is a steady process of distillation and condensation of ethylene glycol. When the temperature of the top of the column, the process of distillation of ethylene glycol is slowing down. When the temperature drops below the 75oWith ethylene glycol increases the amount of water and boiling fractions.

Such process parameters of ethylene glycol allow unlike the prototype consistently on different desks is th water with ethylene glycol of less than 1 mg/l, i.e. less MAC. Thus, the proposed method of disposal of antifreeze has technological advantages over the prototype. In addition, it is environmentally friendly, because warded off water contains valid contents of toxic glycol and is not a source of secondary pollution of natural waters.

In table. 1 shows examples of experiments on the allocation of ethylene glycol, in which find the optimal process conditions. In the process periodically Argonauts water, then glycol.

Experiments 6, 7. According to a known method (prototype).

The technique of the method.

For each test, a sample was taken weighing 300 grams.

In all the experiments to distillation samples of spent antifreeze held the office of oil and sludge in the glass separating funnel.

The sludge was separated from the bottom, the amount of sludge is 2-5% of the download.

Then poured the solution of spent antifreeze into the conical flask. The top layer consists of oil (0,5-1%), which is drained from a separating funnel at last.

Then there was the alkalization samples of spent antifreeze. Spent antifreeze had a pH of 5.0-7.0. The indicator ion is oru waste antifreeze was added to portions of the crystalline sodium hydroxide with continuous peremeshivanii and pH control. the pH of the waste antifreeze solutions 8,5-13. After that conducted experiments on the distillation.

The installation consisted of a distillation flask, equipped with a 48-Christmas reflux condenser, a nozzle with a thermometer. Distillation the flask was placed in a silicone bath with dual thermometer: thermometer to register the temperature in the bath and contact thermometer with a temperature controller connected to the hotplate.

Heating was carried out using hot plates with a sheathed heating element. The temperature of the vapor was measured with a thermometer installed in the nozzle. The exhaust steam was admitted to direct the fridge with water cooling.

After the distillation of water fraction and the beginning of the distillation fractions of ethylene glycol water cooling was removed, and further the fridge were used as air. The condensate formed in the fridge, came in a special switchgear (spider) with alonger with tap to attach a vacuum pump to create the necessary vacuum. Switchgear consisted of several flasks on the sections for alternately sampling fractions in different flasks.

The mass of each fraction was determined by weighing, then the heat-resistant glass, the connecting elements of the unit-equipped sections, ensuring the integrity of the installation. The vacuum pump is equipped with vacuumation fixing the vacuum in the system.

Products recycling waste antifreeze was analyzed as follows. In etilenglikolevye fraction was determined by the mass fraction of main substance, color, mass fraction of acids in distilled water - ethylene glycol. In addition, it was determined the completeness of extraction of ethylene glycol. Analyses of ethylene glycol was carried out according to GOST 19710-83, the content of ethylene glycol in water was determined by the method of micromachinery, the completeness of extraction of ethylene glycol is the difference between its content in a sample of spent antifreeze and number removed from this sample of ethylene glycol.

The results are given in table.2.

In the processes of waste antifreeze according to examples 2-5 turns out high-quality ethylene glycol, suitable for implementation on the market. But you can see that the transition to higher vacuum (example 5) slightly reduces the yield of ethylene glycol, to the same high vacuum technologically more difficult to provide. Insufficient proslushivaniya (example 1) with etilogy who meets the requirements of GOST 19710-83. Under the conditions of distillation according to the prior art (examples 6, 7) supported relatively high residual pressure in the column, and intensified the process of distillation by maintaining a high temperature process. But, as the results of the experiments (see tab. 2, examples 6, 7), we obtain the glycol does not meet certain standards GOST 19710-83 quality.

The advantage of the proposed method of disposal of that water and ethylene glycol are of high quality and can be used as commercial products, and the yield of ethylene glycol 2-5% more.

The method of disposal of waste automotive antifreeze, including sucks raw materials from oil and sludge, water distillation, and the distillation of ethylene glycol under vacuum, characterized in that prior to being fed into distillation column antifreeze is alkalinized to pH 11,0-13,0, the distillation of water is performed at a residual pressure of 12 to 24 kPa, the temperature in Cuba 76-92oWith, in the upper part of the column 45-60oWith, and the distillation of ethylene glycol is at a residual pressure of 0.7 to 2.5 kPa, at a temperature of cube 90-150oWith, in the upper part of the column 75-105oC.

 

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