ES2358250A1 - Desalination of sea water by sequential precipitation of marine salts, without energy consumption and reuse of reagents. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Desalination of seawater by sequential precipitation of marine salts, without energy consumption and reusing reagents. In fig.1 we see how co2 and nh3 are introduced into seawater, so that they react giving rise to nh4 cl in dissolution and nahco3 precipitate see fig.2. By filtration we pass the nh4 cl to the next tank where it reacts with the calcium bicarbonate ca (hco3)2 see figure 3 to give cacl2 precipitate, CO2 and ammonia gas that we will reinsert in the process. And we get fresh water fig.5. The precipitated cacl2 makes it react with the nahco3 that comes from fig.2 in a separate tank with the minimum amount of water possible fig.6, to give a concentrated nacl solution, co2 gas to be reused and caco3 precipitated fig.7. We filter and evaporate to obtain common salt. Subsequently the caco3 we will react with the bicarbonate ion that comes from the addition of co2 to give a calcium bicarbonate solution fig.8 that we reinserted in our cycle in the fig.3

Description

Desalination of seawater by sequential precipitation of sea salts, without consumption energy and reusing reagents.

Background of the invention

The present invention relates to the desalination of seawater, through a process of precipitation of sea salts that are dissolved in water from the sea, in different phases or sequences, to obtain water sweet, recovering the reagents used in the process and without cost energetic.

This process is a qualitative advance in the processes known so far, whose improvements affect the energy saving and environmental pollution.

Object of the invention

Obtaining fresh water for consumption human and for agricultural use, it is a priority at the scientific level, to prevent the lack of water resources resulting in conflicts between communities and countries. The numerous processes are known technology that have sought desalination of seawater as natural source for obtaining fresh water, existing in the current processes of desalination by reverse osmosis and processes of evaporation and distillation that aim at desalination. The investment costs, energy costs desalination. The costs energy of these systems and the economic cost of fresh water which is made available to farmers and users, make these desalination systems have not been applied in a manner widespread, especially in societies with few resources economic that are, perhaps, those that most need the resources water for its development.

We must also highlight that the technology current most widespread in desalination of seawater, is the reverse osmosis, whose process involves a high energy cost and produces significant contamination with rejection brine, which when poured into the sea, increases marine salinity.

To avoid the inconvenience of these technologies, the owner of the present invention, has developed a desalination process of seawater, which does not need energy to obtaining fresh water, based on a chemical physical process, which removes ions from sea salts, by means of a sequential precipitation, which allows to reduce the costs of fresh water obtained. It does not produce rejection brine, and they are removed the ions dissolved in seawater, turning them into salt common. These characteristics are the object of this invention.

Description of the invention

In a dish tower or reaction tank, We introduce seawater, which we have previously filtered. In the dish tower or reaction tank, we add carbon dioxide (CO 2) and ammonia (NH 3), both in the form of gas. The CO2 it is diluted in water forming the bicarbonate ion (HCO 3 -) and Ammonia (NH3) when diluted forms the ammonium ion (NH4 +). The reaction with the dissolved ions it contains seawater, and which are chlorine, sodium, calcium and magnesium, mainly, they react with the bicarbonate ion HCO 3 - and ammonium NH 4 +, to form ammonium chloride (NH 4 Cl), sodium bicarbonate (NaHCO3), calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). Sodium bicarbonate NaHCO 3, calcium carbonate CaCO 3 and carbonate MgCO3 magnesium precipitate, leaving only the solution ammonium chloride NH4 Cl. Sodium bicarbonate NaHCO3, the calcium carbonate CaCl2 and magnesium carbonate MgCO3, precipitates are removed from the tower of dishes.

After this first sequence of precipitation, only the ammonium chloride is dissolved in the water NH4 Cl, which we passed to another reaction tank.

In this second deposit we add to the Calcium bicarbonate solution Ca (HCO3) 2 in solution, so that it reacts with ammonium chloride NH4 Cl.

In said reaction the chlorine ion Cl - reacts with the calcium ion Ca 2+, to form the chloride calcium CaCl 2 and ammonia NH 3 and carbon dioxide CO 2, after agitation and vacuum, is released in the form of gas, that we recover it and introduce it back into the first reactor or dish tower

The calcium chloride CaCl2 precipitates and is collect for reuse.

In this second precipitation sequence, the sea water, has been free of chlorine ions Cl -, sodium Na +, calcium Ca 2+ and magnesium Mg 2+, which is the largest salt ion concentration it contains. Said fresh water, free of salts, is collected for use for agricultural use and for human consumption, prior to its purification.

To recover calcium bicarbonate Ca (HCO 3) 2, as one of the reagents that they are part of the process, we use two phases, which take place in two successive reaction tanks. In a first deposit, we make react, in aqueous solution, calcium chloride with the baking soda, to form:

CaCl2 + 2 NaHCO 3 - - - - - - - - - - - - - - - - - - 2 NaCl + CO 2 + CaCO_ {3}

Carbonic anhydride (CO2) is released in the form of gas and we recover it for the next process.

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Calcium carbonate (CaCO3) precipitates and is collected for the next phase and the remaining sodium chloride (NaCl) in saturated solution, it is removed from the tank so that by evaporation common salt is obtained.

In a second tank, carbon dioxide (CO2) we introduce it in aqueous solution to form the ion carbonic (HCO 3 -) and we add calcium carbonate (CaCO_ {3}) obtained above, to achieve the passage of calcium carbonate CaCO 3 to calcium bicarbonate Ca (HCO 3) 2, which is soluble in water, of according to the reaction:

CaCO 3 + CO 2 + H 2 O - - - - - - - - - - - - - Ca 2+ + 2 HCO 3 -

Once the calcium bicarbonate is obtained Ca (HCO 3) 2 which is soluble in water, which we will introduce in the described reaction tank that only contains ammonium chloride (NH4Cl), so that they react as follows shape:

Ca (HCO 3) 2 + 2 NH4 Cl - - - - - - - - - - - Ca Cl 2 + 2 CO 2 + 2 NH 3

As we have already indicated, carbonic anhydride CO2 and NH3 ammonia, by stirring and vacuum, are recovered in the form of gas, for the initial phase of the process. He calcium chloride CaCl2 is reused again for the second phase, where we react the sodium bicarbonate NaHCO 3 with the calcium chloride CaCl2.

The process allows obtaining fresh water, recovering carbon dioxide CO 2, ammonia NH 3 and calcium bicarbonate Ca (HCO 3) 2 which are the Reagents needed to remove dissolved ions in water from sea.

Brief statement of the figure

In fig. 1 we see the development of the process. Thus (1) we see how CO 2 and NH 3 are introduced into seawater, to react giving rise to NH4Cl in solution and Precipitated NaHCO3 (2).

By filtration we pass the NH4Cl to next tank where it reacts with calcium bicarbonate Ca (HCO 3) 2 (3) to give CaCl 2 precipitate, CO2 and ammonia gas that we will reinsert in the process (4). And we get fresh water (5).

The precipitated CaCl_2 is reacted with NaHCO_ {3} (2) in a separate tank with the minimum amount of possible water (6), to give a concentrated solution of NaCl, CO2 gas that we will reuse and precipitated CaCO3 (7).

We filter and evaporate to obtain salt common.

Later the CaCO_ {3} we will do it react together with the bicarbonate ion that comes from the addition of CO2 to give a calcium bicarbonate solution (8) that We will reinsert in our cycle (3).

Description of the preferred embodiment

Desalination of seawater by sequential precipitation of sea salts, consists of two phases successive processes, in order to obtain fresh water and recover the reagents used in the process. The first phase sequential is the reaction of carbon dioxide CO2 and the NH3 ammonia both in gas form, for reaction with salts that are dissolved in seawater. (one). He sodium bicarbonate NaHCO 3, calcium carbonate CaCO 3 and the MgCO3 magnesium carbonate, precipitate. The solution remains NH4Cl ammonium chloride, which is transferred to another deposit of reaction (2). In this deposit calcium bicarbonate is introduced Ca (HCO 3) 2, in solution (3), so that react forming calcium chloride NH4Cl, which precipitates and releasing carbon dioxide CO2 and ammonia NH 3 in the form of gas (4). The water that is in the solution, it is free of ions and consequently, it is fresh water, available for irrigation or prior purification, for human consumption. Is transferred to a warehouse for storage. (5).

The second phase consists in the recovery of reagent used in desalination which is calcium bicarbonate Ca (HCO 3) 2. Carbon dioxide anhydride CO 2 and NH3 ammonia, has already been recovered in the previous phase in the form of NH3, has already been recovered in the previous phase in the form of gas.

To do this, in another reaction tank, (6) we introduce the sodium bicarbonate NaHCO3 and calcium chloride CaCl2, obtained as resulting products in the first process (4 and 2). The reaction of sodium bicarbonate NaHCO3 with CaCl2 calcium chloride produces NaCl sodium chloride and calcium carbonate CaCO 3) releasing carbonic anhydride CO2 in the form of gas. Said reaction is carried out in solution. concentrated, to favor the reaction. Calcium carbonate CaCO 3 precipitates and NaCl sodium chloride remains in the saturated solution, which we collect (7), by centrifugation, so that by evaporation it crystallizes as common salt.

We introduce calcium carbonate CaCO 3 in another reaction tank in aqueous solution and we introduce the CO2 carbonic anhydride obtained in the previous reaction (8). CaCO 3 calcium carbonate, reacting with the ion bicarbonate HCO 3 -, produced upon dissolution of the anhydride carbonic CO2 in water, it becomes calcium bicarbonate It is soluble in water.

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Calcium bicarbonate Ca (HCO 3) 2, thus obtained, is introduced into the reaction tank (3), where ammonium chloride is found NH4Cl, in solution, to start the process again.

The fundamental characteristics is that through sequential precipitation, the ions of the dissolved salts, by precipitation, leaving the water free of you go out. The process would be unfeasible, economically, if not recycle the elements involved in the process, such as CO 2 carbonic anhydride, calcium bicarbonate Ca (HCO 3) 2 and the ammonia NH 3. Thus, products obtained in the first phase are recycled, such as sodium bicarbonate NaHCO 3 and calcium chloride CaCl 2, for from them, recover the reagents used in accordance with The description already detailed.

The advantages of the system are unquestionable, with compared to current technology, because energy is not consumed as the reverse osmosis process. Common salt NaCl is obtained as by-product, which crystallizes by evaporation, for use in the market, without polluting the environment, or salinizing the sea with the brine. No external energy input is needed, as in the distillation or evaporation process, so the cost of production of the cubic meter of fresh water is much lower with the described system of sequential precipitation, which systems currently employed

They will be independent of the object of the invention, the materials used in the reaction tanks and in the components necessary for the transport of fluids between them, as well as the shapes and dimensions and accessory details, provided and when they do not affect the essentiality.

Claims (2)

1. Desalination of seawater by sequential precipitation of sea salts, without consumption energy and reusing reagents, consisting of the dissolution of carbon dioxide CO 2 and ammonia NH 3 in sea water, so that in its reaction with the sodium ions Na + and Chlorine Cl -, dissolved in seawater, form bicarbonate sodium NaHCO 3 and ammonium chloride NH 4 Cl. Baking soda sodium NaHCO 3 precipitates and the ammonium chloride NH 4 Cl is It is in solution. The NH4Cl ammonium chloride is reacted in solution, with calcium bicarbonate Ca (HCO 3) 2, in solution, so that in its reaction forms calcium chloride CaCl2, which precipitates and is release, by agitation and vacuum, carbon dioxide CO2 and NH3 ammonia in the form of gas, which are recovered For the previous process. The water is free of ions and in consequence is fresh water for agricultural use or human consumption.

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2. Desalination of seawater by sequential precipitation of sea salts, without consumption energy and reusing reagents, according to the previous claims, consisting of recovering the reagents used, by reacting, in aqueous solution the bicarbonate sodium NaHCO 3 with calcium chloride CaCl 2, to obtain CaCO 3 calcium carbonate, NaCl sodium chloride and anhydride carbonic CO2 in the form of gas. Said carbonic anhydride CO2, previously dissolved, is reacted with the carbonate calcium CaCO 3 to obtain calcium bicarbonate Ca (HCO 3) 2 in solution.