ES2259261A1 - Sea water desalination technique consists of steam boiler based production of by product brine with electricity generation by the steam - Google Patents

Abstract

The sea water desalination technique comprises electricity generation and heating for e.g. reverse osmosis, comprises electricity generation and heating for e.g. reverse osmosis, utilizing the energy of the steam from a boiler, with application of sulfur and lime during the steam generation. Also claimed is apparatus implementing the process. CLAIMED APPARATUS - The apparatus has a desalinated water pipe extending to the shore from the desalinator mounted on a barge anchored at sea. It also yields brine as a by-product.

Description

Procedure and plant for desalination of seawater.

Technical sector of the invention

The invention relates to a method for the desalination of seawater and a desalination plant, particularly intended to treat seawater to obtain of water for consumption.

Background of the invention

Common desalination plants are installed in coastal areas to have direct access to water of sea, which is captured and transported to the plant through pipes of considerable length.

In the plant, the water collected is treated following different processes, the best known being low temperature distillation (mechanical vapor compression or multi-effect distillation) and reverse osmosis, which require a large consumption of heat and electric power, respectively
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At the same time, it may be the case that the demand for produced water varies depending on the weather conditions, which occurs when part of the water is destined for irrigation, so the plant cannot operate at the rate of its maximum capacity if You don't want to produce surplus treated water. Throughout the life of the plant it may even be that its construction and operation is not amortized.
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The location of such a plant it presents other inconveniences related to the elimination of one of the by-products obtained, brine. This water with high salt content is poured into the sea so that the salt it incorporates is diluted when mixed with seawater, however, the high salt concentration in coastal areas affects wildlife and Flora close to the places where the brine is poured into the sea. Similarly, the water collected to obtain water for the consumption can also be affected by pollution, since waters near the coast are usually more polluted than the farthest waters of the coast.

Explanation of the invention.

In the procedure for desalination of seawater object of the invention, the energy stored in the steam produced in a steam boiler is used simultaneously or alternatively for the production of electrical energy and / or for the contribution of heat in reverse osmosis processes and of distillation, respectively, for obtaining, from water of sea, of water for consumption, as the main product, and brine, as the first by-product obtained in the procedure.

In essence, the procedure is characterized because it includes the steps of adding sulfur and lime to the boiler of steam during steam production, to obtain plaster, and of removing the mentioned plaster from the boiler, which results a second usable byproduct, obtained in the procedure.

According to another feature of the procedure, the Sulfur is added to the boiler contained in the fuel.

Preferably, the fuel is coke of oil and / or coal and / or fuel oil and / or orimulsion, and the content of Sulfur in the fuel is 1 to 8% by weight.

With the process of the invention, the high energy consumption of the plant is used not only for the obtaining water for consumption, it also takes advantage for the production of plaster, which adds value to the procedure.

It is also the object of the invention a plant desalination plant intended to treat seawater for the production of Water for consumption. The plant of the invention comprises a fluidized bed steam boiler, which produces steam superheated at high pressure, fed with petroleum coke and / or coal and / or fuel oil and / or orimulsion, containing sulfur, adapted for the extraction of the plaster obtained as by-product when sulfur is combined with lime inside the boiler. The plant also includes a steam turbine for electric power production, in which steam expands produced in the boiler, and a reverse osmosis installation and / or distillation for production, from seawater, water for consumption, as the main product, and brine as another by-product, in a way known per se.

In a preferred embodiment, the plant comprises also at least one two-cycle diesel cycle engine, which uses as fuel oil and / or orimulsion, for the electric power production for the electricity supply of al less the installation of reverse osmosis and / or to dump the network electric transport.

According to another feature of the invention, the plant is installed on a floating barge anchored at a distance from the coast and comprises at least one pipe of connection to the mainland, through which water is sent to the consumption produced in the plant and means for the discharge of the brine at a point located at a similar distance from the coast to the existing one between the barge and the coast.

In this way, the collection of water in areas near the coast and at the same time the brine is poured into remote areas of the coast, avoiding future damage to the ecosystem.

According to another feature of the invention, the plant also includes a transfer station, installed in the coast, which receives the water for consumption obtained at the plant to store and / or pump it to its destination.

In a preferred embodiment, the plant comprises an electrical connection consisting of an underwater cable for the shipment to the coast, or on land, of electric power remnant of the water production process for consumption and / or the produced by the engine or two-cycle diesel engines time.

According to another feature of the invention, the transfer station is powered by energy remnant of the process and / or produced by the engine or engines two cycle diesel cycle.

According to another feature of the invention, the floating barge is mobile and self-propelled, so the plant It can be transported to a different place, being located in those places where the demand for water for consumption is Temporarily more necessary.

Brief description of the drawings

The attached drawings illustrate, by way of non-limiting example, a desalination plant according to the invention. In these drawings:

Fig. 1 is a schematic representation of a plant according to the invention; Y

Fig. 2 schematically shows a plant according to the invention, installed in a floating barge away from the coast.

Detailed description of the drawings

The desalination plant 43 of the drawings is installed on a floating platform 41, anchored to a certain distance from the coast 42, preferably 1 to 5 miles, which it is connected to the mainland through two pipes 23 and 28 through  of which water is pumped respectively for consumption with different concentrations of salt from the ground platform. TO in turn, the energy is also grounded from the platform electrical surplus produced in the plant by means of a cable submarine 44. On the coast, a transfer facility receives the water for consumption, sent through the pipes, that the Store and / or pump it to its destination. In the same installation the Water for consumption can undergo a post-treatment before Be pumped to its destination. Such transfer facility can feed, where appropriate, the electrical energy produced in the barge.

In the example of Fig. 1, it is observed that the desalination plant 43 comprises a bed 1 steam boiler circulating fluidized, in which it is introduced through the conduction 31 petroleum coke, whose sulfur content ranges between 2% and 6% by weight, as fuel; through the 32 air conduction, to provide oxygen to the boiler; and through of driving 33 cal. The sulfur contributed to the boiler in the fuel is combined with the lime added to the bed of the boiler and gypsum is produced, which is extracted from it through the conduction 34. In this way the sulfur contribution to the boiler 1, whose emission into the atmosphere is harmful, turns out to be a benefit since from this the main by-product of the plant, the plaster, mixed with other components, which results Very useful for the construction industry. Naturally,  it is possible to say that the boiler 1 of circulating fluidizing bed could be of the type of bubbling or drag fluidizing bed.

The steam produced in boiler 1 is transported, through conduction 26, to the entrance of a group turbogenerator, comprising a steam turbine 6 that moves a alternator 7 for the production of electrical energy that will be used in the facilities of the plant to obtain water for consumption, as will be explained later, for feed the secondary equipment of the plant (fans, mills, pumps, conveyors, etc.) and stations transfer or pumping as represented by the power line 27. The combustion waste gases are evacuated from the boiler 1, and after passing through the gas cleaning system 2, are emitted into the atmosphere through conduction 22.

The plant in Fig. 1 combines different facilities for obtaining water for consumption from of sea water. Specifically, most of the energy electric produced by the alternator 7 is used for the high pressure pump drive 8 of an installation 3 for the treatment of seawater by reverse osmosis, and the remaining energy is used by the secondary teams of the plant (fans, mills, pumps, conveyors, etc.) and by the transfer or pumping stations, while the steam that leaves the turbine 6 is used as a source of energy for the seawater treatment through a distillation system of multiple effect

The reverse osmosis desalination system includes the steps of collecting seawater, pretreatment 5 and pumping at high water pressure, through conduction 25, for heating in heat exchanger 10 and subsequently for desalination in the osmosis installation inverse 3. As a result of the system water is obtained for the consumption, which is transported by the outlet pipe 23, with interposition of heat exchanger 10, towards the mainland, also obtaining rejection water, with high salt content, which it is transported by conduction 29, whose energy contained in form of heat is used in heat exchanger 10 and whose energy in the form of pressure is also harnessed in the recuperator 9. Optionally, the water is supplemented supply of high pressure pumps with water from distillation system cooling through conduction 35

On the other hand, the distillation system includes the steps of seawater collection, pretreatment 5 and transport by conduction 29 to the installation of distillation 4, in which the heat used for evaporation of the seawater is supplied by the steam output of turbine 6 which it is transported by conduction 24. As a result it is obtained water for consumption, which is transported by the outlet pipe 28, with interposition of heat exchanger 10 to ground firm, as well as water with high salt content, whose heat it is used in heat exchanger 10 and then it is discharge into the sea through conduction 20. Water from cooling is poured through conduit 35, which optionally it is fed to the reverse osmosis system.

The plant comprises a closed circuit for the water to vaporize in the boiler 1. Water in a liquid state is driven by pump 21 to the boiler, in which the contribution of heat causes its vaporization. From the boiler, the steam is driven by conduction 26 to turbine 6, from which leaves at low pressure by conduction 24, a branch of which bifurcates towards condenser 36 to control the pressure of circuit condensation and perform full condensation when the distillation system is out of service, while another branch conducts steam to distillation installation 4 in the that this cedes part of the heat before being reintroduced into the boiler 1.

The installation of the 43rd floor on a barge floating 41, anchored at a distance from the coast, prevents the spillage of the brine, high concentration of sodium chloride, in water Coastal The brine is diluted away from the coast, which represents  an unquestionable environmental advantage, since the discharge of brine in coastal waters affects species with low mobility and to plants in a very negative way. In addition, another aspect very important environmental is the fact that the emissions of carbon dioxide from steam boiler 1 is diluted in the atmosphere at important distances from the coast, and therefore far of urban centers.

In turn, the use of energy contained in the steam produced in boiler 1 is maximum, set that uses its energy in the form of pressure and its thermal energy in two desalination processes, reverse osmosis and multi-effect distillation, which achieves, at the same time, the possibility of obtaining water for consumption with at least two different qualities in relation to its salt content, depending on the process through which it is obtained, which may result interesting since the two qualities of water can go to two different purposes, such as human consumption or, for example, the irrigation.

Another aspect to highlight is obtaining a second byproduct, plaster, as a result of the process of desalination, which solves the related environmental problem with the emission of sulfur-containing gases into the atmosphere.

It is noted that simultaneously to the plant exploitation, field extensions are planned with tree species to compensate for dioxide emissions from carbon from the use of fossil fuels in the process carried out in the plant.

Claims (11)

1. Procedure for the desalination of seawater in a desalination plant, in which the energy stored in the steam produced in a steam boiler is used simultaneously or alternatively for the production of electrical energy and / or for heat input in processes of reverse osmosis and distillation, respectively, for obtaining, from seawater, water for consumption, as the main product, and brine, as the first by-product obtained in the process, characterized in that it comprises the steps of providing sulfur and lime to the steam boiler, during steam production, to obtain gypsum, and to extract the said gypsum from the boiler, which results in a second usable by-product, obtained in the process. 2. Method according to claim 1, characterized in that the sulfur is supplied to the boiler contained in the fuel. 3. Method according to claim 2, characterized in that the fuel is petroleum coke and / or coal and / or fuel oil and / or orimulsion. 4. Method according to claims 2 or 3, characterized in that the sulfur content in the fuel is from 1 to 8% by weight. 5. desalination plant (43), particularly for treating seawater to produce drinking water, comprising a boiler (1) steam circulating fluidized bed, which produces superheated steam at high pressure, fed with coke of petroleum and / or coal and / or fuel oil and / or orimulsion, with sulfur content, and adapted for the extraction of gypsum obtained as a byproduct when sulfur is combined with lime inside the boiler, and because it also includes a steam turbine (6) for the production of electrical energy, in which the steam produced in the boiler is expanded, and a reverse osmosis (3) and / or distillation (4) installation for production, from water of sea, of water for consumption, as the main product, and brine as another by-product, in a manner known per se. 6. Plant according to claim 5, characterized in that it also comprises at least one two-cycle diesel engine, which uses fuel oil and / or orimulsion as fuel, for the production of electrical energy to drive at least the reverse osmosis installation from the plant and / or to dump the transport electricity network. 7. Plant according to claim 5 or 6, characterized in that is installed on a floating barge (41) anchored offshore (42), and that the plant comprises at the least one connecting pipe (23, 28) with mainland , through which water is sent for consumption produced in the plant (43), and means for the pouring of the brine at a point located at a distance from the coast similar to the distance between the barge and the coast. 8. Plant according to claim 7, characterized in that it further comprises a transfer station, installed on the coast, which receives the water for consumption obtained in the plant for storage and / or pumping it to its destination. 9. Plant according to claims 7 or 8, characterized in that it comprises an electrical connection (44) consisting of an underwater cable for sending to the coast (42), or to the mainland, the remaining electrical energy of the process carried out in the plant and / or that produced by the two-cycle diesel engine or engines. 10. Plant according to claim 9, characterized in that the transfer station is fed by the remaining energy of the process and / or produced by the two-cycle diesel engine or engines. 11. Plant according to any one of claims 7 to 10, characterized in that the floating barge (41) is mobile and self-propelled.