SU1507742A1 - Method of producing potable water from distillate - Google Patents

Abstract

The invention relates to technology and technology for the production of potable water from distillate desalinated installations. The purpose of the invention is to intensify the process of formation of calcium bicarbonate during the interaction of gaseous, solid and liquid phases, simplifying the process of obtaining drinking water and reducing its cost while maintaining quality. The method is that the reaction between calcium hydroxide and carbon dioxide is carried out in an ejector. For this, 20–25% of the initial volume of distillate is transferred via a bypass pipeline to an ejector, where calcium hydroxide and carbon dioxide are supplied. The resulting solution of calcium bicarbonate (without precipitation of the solid phase of calcium carbonate) is mixed with the main stream of distillate to obtain standard water of bicarbonate class. 1 tab.

Description

The invention relates to a technique and technology for the production of potable water from distillate desalination plants, in particular, to the design of plants for the stabilization and mineralization of distillate, and can be used in stations for the preparation of drinking water from sea and salt water, as well as on sea vessels.

The purpose of the invention is to intensify the process of formation of calcium bicarbonate during the interaction of the gaseous, solid and liquid phases, simplifying the process of obtaining drinking water and reducing costs while maintaining quality.

The method is as follows.

20-25 from the initial volume of distillate through the bypass pipeline is fed into the ejector, into the vacuum chamber of which calcium hydroxide solution and carbon dioxide are fed. The ratio of feed rates of distillate, calcium hydroxide and carbon dioxide is 1: 0.00031-0.00039: O, 0072-0.0090, respectively. The resulting solution, containing 680–850 mg / l of calcium bicarbonate (without isolation of the solid phase of calcium carbonate), is mixed with the main stream of distillate and diluted 4–5 times to obtain the mineral: nh

VI

31507

water of standard hydrocarbonate class. The ratio of flows through the main and bypass pipelines was determined by their diameters, the optimum ratios of the reagent feed rates were determined experimentally.

Increasing the doses of reagents leads to the formation of a solid phase of calcium carbonate, i.e. waste of reagents and complication of the process due to the introduction of a phase of separation of the solid phase, and, ultimately, to an increase in the cost of drinking water. Reducing doses is not rational because of the increase in the volume of pumped liquid to maintain the quality of drinking water and increase its cost. At the same time, at such ratios of distillate and reagents, the concentration of calcium bicarbonate solution leaving the ejector allows dilution of this distillate 4–5 times to obtain drinking calcium-bicarbonate class drinking water meeting the requirements of GOST Drinking water hygiene standards of the USSR Ministry of Public Health for drinking water obtained from distillate. Both an increase and a decrease in the dilution rate lead to a deviation of the properties of water from the optimal parameters of these requirements, moreover, a decrease in the dilution rate leads to an increase in the volume of pumped water being treated, i.e. to an increase in cost. The quality indicators of the initial and treated distillate, as well as the produced drinking water are presented in the table.

Example. The original distillate obtained from the desalination of mineralized mine water was pumped to an installation for obtaining drinking water from a distillate with a volume flow rate of 100 l / h. The diameter of the main pipeline of the installation is 20 mm, and the bypass pipe is 10 mm. Thus, through the bypass pipeline, 20 of the initial volume of the distillate flows through the water jet pump, i.e. 20 l / h 2.6 l / h-0.3% calcium hydroxide solution from the stirrer tank and 0.18 kg / h of carbon dioxide from the cylinder enter the dilution chamber of the water-jet pump through the dosing units. An increase in the doses of reagents leads to the formation of a solid phase of calcium carbonate, a decrease is irrational due to an increase in the amount of liquid removed.

After the water jet pump, the calcium bicarbonate solution is dissolved in (see table) 30 mg / l Ca and +20 mg / l HC07 - With a total content of 1200 mg / l, and after mixing with the main stream (80 from the initial volume), dilution occurs solution of distillate 5 times to obtain drinking water. The composition of the initial and treated distillate, as well as the produced water is presented in the table.

Similarly to the above, the experiment was carried out with the diameter of the main pipeline 21.3 and bypass - 12.3 mm (ratio: 1.73: 1), the result of which is also presented in the table.

The choice of such limiting ratios of the main and bypass pipelines is based on the need to maintain the quality of drinking water at an optimal level that meets the requirements of GOST and hygienic standards for desalinated drinking water (total salinity 20o - 300 mg / l; 50-150 mg / l; 50-150 mg / l, etc.), as well as on striving 1: 1 to achieve the maximum effect at minimum costs, so the solution of the above composition obtained after the ejector must be diluted by kS times, i.e. 20-25% of the total distillate volume is supplied to the water jet pump, which is determined by the ratio of the diameters of the main and bypass pipelines 1.73-2.00: 1. Changing the ratio of the pipelines will change the dilution rate of the calcium bicarbonate solution up or down. water will not meet the above requirements for desalinated drinking water.

The results in the table show that the drinking thief obtained from the distillate was desalinated, with a total mineralization of 230-300 mg / l, stable in corrosion. And in relation to carbonate deposits in pipelines (stability index (I st.)

has a positive value with a value less than one) and in all other indicators meets the requirements of GOST Drinking water.

The invention allows to significantly reduce the cost of electricity, as well as to reduce the residence time of the treated distillate by a factor of ten, which, together with a 4-5 times decrease in the amount of distillate being processed, significantly (by a factor of tens and hundreds) reduces the dimensions of the installation and, consequently, TejibHo, reduce capital and operating costs and the cost of obtaining drinking water while maintaining or even some improvement in its quality indicators.

Claims (1)

The formula of the process and the method of obtaining drinking water from distillate, including the treatment of the latter with calcium hydroxide and carbon dioxide, characterized in that, in order to intensify the process of formation of calcium bicarbonate in the interaction of gaseous, solid and liquid phases, the process of obtaining drinking water and reducing the cost while maintaining quality, is treated with 20 ... 25% of the total amount of distillate in the ejector with a ratio of distillate feed rates, calcium hydroxide and carbon dioxide 1: 0 , 00031-0,00039: 0.0072-0.0090 and the resulting solution is mixed with the remaining amount of distillate.