BJERKAN, Trond, Aas (Gamle Tregde Vei 7, Mandal, N-4516, NO)
| C l a i m s 1. A device for water treatment plant (1) for water, where the water treatment plant (1) comprises a low- pressure evaporator (2) for vaporising water at ambient temperature, and where the evaporator (2) is connected to a first downcomer (8) and to a condenser (4) for condensing of water vapour, and where at least impure or salt water is supplied to the evaporator (2) , as cleaned or desalted water is led out from the condenser (4), c h a r a c t e r i s e d i n that a first pump (12) for pumping water out is connected to the first downcomer (8) , whereby an underpressure is maintained in the evaporator (2) by a combination of the head of the first downcomer (8) and an underpressure from the first pump (12) . 2. A device according to claim 1, c h a r a c t e r i s e d i n that the impure or salty water is led through a circuit (32) in the condenser (4) before being led into the evaporator (2) . 3. A device according to claim 1, c h a r a c t e r i s e d i n that the impure or salty water is led through a solar panel (34) before being led into the evaporator (2) . 4. A device according to claim 2 or 3, c h a r a c t e r i s e d i n that a circuit in the condenser and in the solar panel (34) is closed, as a separate fluid circulating through the condenser (4) or the solar panel (34) gives off heat to the impure or salty water . 5. A device according to claim 1, c h a r a c t e r i s e d i n that the first pump (12) is controlled by a first level meter (10) positioned in the evaporator (2) or in the first downcomer (8) . 6. A device according to claim 1 wherein the condenser (4) is provided with a second downcomer (16) c h a r a c t e r i s e d i n that a second pump (22) for condensed water is connected to the second downcomer (16) , whereby an underpressure in the condenser (4) is maintained by a combination of the first downcomer (16) head and an underpressure from the second pump (22) . 7. A device according to claim 6, c h a r a c t e r i s e d i n that the second pump (22) is controlled by a second level meter (20) positioned in the condenser (4) or in the second downcomer (16) . |
This invention relates to a water treatment plant. More particularly it concerns a water treatment plant for water where the water treatment plant comprises a low-pressure evaporator for evaporating water at ambient temperature, and where the evaporator is connected to a first downcomer and to a condenser for condensing of water vapour, and where water at least being impure or salt is supplied to the evaporator, as cleaned or desalted water is led out from the condenser.
By salt water is in this context meant water that may contain salt such as salt water, brackish water, ground water and brine .
There is a considerable demand for clean and desalted water in large parts of the world. In dry areas for example, large areas would be possible to be put into production if sufficient amounts of desalted water were available.
Known water treatment plants are often based on heating the water by means of an energy source, whereby the water turns to steam before it thereafter is cooled and condensed. It is self-evident that the energy need in this method is considerable . Another method for desalting of water utilises so-called reversed osmosis. Plants of this kind are relatively complex and energy demanding.
In areas where the need for water is greatest there is in addition often a limited infrastructure and thereby also a shortage of electricity and other available energy.
The object of the invention is to remedy or reduce at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art.
The object is achieved by the features disclosed in the below description and in the subsequent claims.
There is provided a water treatment plant for water where the water treatment plant comprises a low pressure evaporator for evaporation of water at ambient temperature and where the evaporator is connected to a first downcomer and to a condenser for condensing of water vapour, and where impure or salt water is supplied to the evaporator, as cleaned or desalted water is led out from the condenser. The water treatment plant is characterized in that a first pump is connected to the first downcomer, whereby underpressure in the evaporator is being maintained by a combination of downcomer head and underpressure from the first pump.
Water treatment plants wherein the evaporation takes place at ambient temperature are contingent upon the water being at low pressure. It is known to maintain this low pressure by means of the liquid column in a downcomer running between an evaporator and a container or a reservoir on the ground. A downcomer length of 10-12 metres is necessary to achieve sufficient underpressure. Placing an evaporator at such a great height above the ground is complicated and involves large costs when the evaporation plant is to be placed in less developed areas.
The invention makes it possible to reduce the downcomer length by letting a first pump produce a part of the necessary underpressure in the evaporator. The downcomer effects that the first pump power may be less than it would have to be if a downcomer was not present. This is important when the power supply to the first pump comes from a power source having limited output, such as a solar panel.
In hot, dry areas the water to be cleaned is often collected from a salt-water dam. It is known that salt-water dams can have a considerably higher temperature down in the water than at the surface. The heat energy in such dams is therefore well suited for driving a Rankine cycle engine. This engine may be utilised for driving the first pump.
The salty or impure water may be led through a circuit in the condenser before being led into the evaporator. Energy given off from steam in the condenser during condensation is thereby transferred to the water before it flows into the evaporator. Further heat may be supplied to the impure or salty water before it is led into the evaporator, for example by being led through a solar panel . Both the circuit in the condenser and in the solar panel may be closed, that is that a separate fluid circulating through the condenser or the solar panel gives off heat to the impure or salty water.
The water level in the evaporator may be regulated by the pump being controlled by a level monitor in the evaporator or in the downcomer.
The condenser may be provided with a second downcomer, as a second pump for condensed water is connected to the second downcomer. Underpressure in the condenser is provided by a combination of the height of the first downcomer and underpressure from the second pump.
The water level in the condenser may be regulated by the pump being controlled by a level monitor in the condenser or the downcomer .
The water treatment plant according to the invention is arranged for relatively simple installation and operation, at the same time as it is emphasized that the operation be carried out with as little need for external power supply as possible. It is thus possible to run a water treatment plant of this kind by means of energy from a salt-water dam.
In the following is described an example of a preferred embodiment being illustrated in the accompanying drawings, wherein :
Fig. 1 shows a wiring diagram for a water treatment plant according to the invention;
Fig. 2 shows in a side view a principle sketch of a water treatment plant according to Fig. 1;
Fig. 3 shows an end view of the plant of Fig. 1.
In the drawings the reference numeral 1 indicates a water treatment plant comprising an evaporator 2 and condensers 4 connected to the evaporator 2 by means of respective condenser channels 6.
A first downcomer 8 runs from the evaporator 2 lower bottom portion, via a first level meter 10 and a first pump 12 down to a first tank 14. Correspondingly, a second downcomer 16 runs from the condenser 4 outlet 18, via a second level meter 20 and a second pump 22 down into a second tank 24.
A supply pump 26 connected to a supply pipe 28 for salt-water is arranged to be able to supply the evaporator 2 with water via nozzles 30. In this preferred embodiment the supply pipe 28 is connected to a circuit 32 in the condensers 6 and to a solar panel 34. A filter having a check valve 36 is arranged in the supply pipe 28.
A gas pump 38 is connected, via a gas pipe 29, between the outlet 18 of the condenser 6 and the second tank 24 to be able to draw non-condensable gases out from the evaporator 2 and the condenser 4.
During operation water to be desalted is pumped into the evaporator 2 by means of the supply pump 26 via the supply pipe 28 and nozzles 30. In the nozzles 30 the water is atomised such that the water gets a relatively large surface to be able to evaporate on. The water is led through the circuit 32 in the condensers 4 and through the solar panel 34 wherein the water absorbs heat from steam being condensed and the sun respectively. The solar panel 34 is not shown in Fig. 2.
Evaporated water from the evaporator 2 flows via the condenser channels 6 into the condensers 4 where it is condensed.
The desired water level in the evaporator 2, and thus the desired underpressure, is controlled by a first level meter 10 arranged to be able to control the first pump 12. The regulating of the level may be carried out by means of start/stop and speed regulation of the first pump 12. The salty water from the first pump 12 flows into the first tank 14. Correspondingly, a water level in the second downcomer 16 from the condensers 4 is maintained by means of a second level meter 20 arranged to be able to start and stop the second pump 22. The desalted water from the second pump 22 flows into the second tank 24.
Since the first and second downcomers 8, 16 are water-filled, the necessary underpressure in the pumps 12, 22 is reduced by the pressure from the pressure head between the first pump 12 and the first level meter 10, and the second pump 22 and the second level meter 20 respectively.
Non-condensable gases are sucked out by means of the gas pump 38, which during starting may also be used to establish a sufficient underpressure in the evaporator 2.
The level meters 10, 20 may comprise not particularly mentioned measuring tanks.
In Figs. 2 and 3 the water treatment plant is shown drawn in two standard 20' containers 40, 42. The containers 40, 42 are in the figures indicated by means of stippled lines.
Being able to deliver the water treatment plant 1 installed in containers 40, 42 contribute further to simplify the installation work.