SU1731736A1 - Method of water treatment - Google Patents

Abstract

This invention relates to applied electrochemistry, in particular to methods for treating water. The aim of the invention is to provide the possibility of using treated water for washing oil in the process of desalting and reducing energy costs. To do this, the water is preliminarily heated to the temperature of the washed oil, and water used is treated in the anode chamber of the diaphragm electrolyzer after reaching the values of the redox potential + 520-670 mV and pH 6.0-6.7. 1 tab.

Description

The invention relates to applied electrochemistry, in particular to methods of treating water, and can be used to prevent the precipitation of liquid salts in the washing process with hot oil containing produced water.

There is a method of reducing natural water by treating it in the cathode chamber of a diaphragm electrolyzer until, during processing, the pH of the catholyte is 12.0 - 13.5 and the redox potential is -90-960 mV while simultaneously passing carbon dioxide through the cathode space, followed by settling.

However, this method of water treatment is difficult to implement, since it is necessary to carry out the process in two stages: first, the treatment in the cathode chamber of the diaphragm electrolyzer is carried out, and with significant energy consumption to achieve the necessary pH values and eH, while passing carbon dioxide, on the second, to carry out sedimentation, and possibly filtering, the precipitate of hardness salts that form. With large volumes of water consumed by flushing (10% of the oil produced), the problem of sludge disposal will arise.

The aim of the invention is to provide the possibility of using treated water for washing oil in the process of desalting and reducing energy consumption.

The goal is achieved by the fact that in a known method of water preparation, including its treatment in a diaphragm electrolyzer, water is first heated to the temperature of the oil being washed, and then treated in the anode chamber of the diaphragm electrolyzer until the redox potential reaches +520 - +650 mV and pH 6.0 - 6.7.

Such treatment allows the process to be carried out in one stage, since no precipitation occurs, there is no need for additional transmission of carbon dioxide and other actions associated with the removal of sediment of hardness salts. At the same time

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energy consumption is significantly reduced by reducing by 5-6 times compared with the known method of processing time in the anode space of a diaphragm electrolyzer to achieve the desired pH parameters and redox potential at the same voltage and current on the electrodes.

The method is carried out as follows.

Fresh water containing calcium hydrogen and magnesium bicarbonates of total mineralization of 2.7 g / l is preheated and then electrolyzed in a diaphragm electrolyzer. The treated water from the anode space is mixed with the reservoir water Korobkovsky NGDU in the ratio of 10: 1 and observe the precipitation.

Example. Fresh water with a total mineralization of 2.7 g / l, a concentration of hardness salts of Ca2 ++ MD2 + -0.124 g / l, bicarbonate HCO3 - 0.268 g / l, the rest is sodium and potassium chlorides heated to 60 ° C and subjected to electrolysis in diaphragm electrolyzer with graphite electrodes. The distance between the electrodes is 75 mm, the diaphragm is equidistant from the electrodes, the current density at the anode is 0.001 A / cm, the voltage on the electrodes is 60V. The processing time is 2-3 minutes, until the minimum value of the anolyte redox potential is reached, eH +520 mV. The water thus treated from the anode space is mixed in a ratio of 10: 1 with produced water from the Korobkovsky NGDU with a total mineralization of 160 g / l, containing 14 g / l of hardness salts (Ca2 + MD), 0.045 g / l of carbonates (NSCOz), the rest is sodium and potassium chlorides. They monitor the precipitation of carbonates. The fresh water: reservoir water ratio of 10: 1 is taken because the desalination process uses 10% of the water from the volume of oil being washed, and the oil used for desalting contains up to 1% of the produced water.

Comparative data of the water preparation process is given in the table.

As can be seen from the table, with the values

Anolyte redox potential less than +520 mV is not observed, i.e. during mixing, precipitation of carbonates is observed, and at values above +650 mV, energy consumption increases with the same

effect, i.e. further enhancement is inappropriate.

Claims (1)

Claims of water treatment including its treatment in the electrode chamber of a diaphragm electrolyzer, characterized in that, in order to ensure the possibility of using water when washing oil during desalting and reducing energy costs, water is heated to the temperature of the oil being washed and treated in the anode chamber of a diaphragm electrolyzer until reaching the value of the redox potential plus 520 - plus 670 mV and pH 6.0-6.7.