JPS602882B2 - Rotary desalination equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a reverse permeable membrane (hereinafter referred to as Rq membrane).

This invention relates to a rotary desalination device that can minimize water production costs by rationally setting the desalination process and the arrangement of separation modules. Conventional seawater desalination equipment using RO membranes uses an RO membrane with excellent desalination performance to recover fresh water by applying high pressure to the seawater and increasing the amount of permeated water. A one-stage desalination process is employed to increase the yield.

To give a numerical example regarding this method, a pressure of 50 to 60 k
9/ Land, desalination rate of 99% or more, freshwater recovery rate of 20~
It is normal to keep it around 30%. The problem with this method is that a large amount of concentrated wastewater (hereinafter referred to as prine) is discarded while still under high pressure, resulting in a large loss of energy. In order to prevent this loss, various measures have been attempted to recover energy from the high pressure brine, but these naturally involve considerable costs. Therefore, in order to reduce the energy loss due to the discharge of this high-pressure brine, it is necessary to reduce the amount of water discharged as much as possible, or in other words, to increase the fresh water recovery rate.To this end, it is necessary to use a high-performance Rq membrane with a high desalination rate. At the same time, the waist area must be increased,
There are limits to this in terms of cost, so it is common practice to increase the pressure applied to seawater as high as possible, taking into account the lifespan of the membrane and other conditions.

Therefore, in this method, the combination of high brine concentration and high pressure places a heavy burden on the membrane, and the permeation performance of the membrane deteriorates rapidly over time, and the recovery rate decreases accordingly. There is a mirror direction. In order to compensate for the above-mentioned drawbacks, this desalination method requires severe pretreatment of seawater.

In other words, in addition to various solids and suspended substances mixed in seawater, chemical substances such as magnesium, calcium, and other compounds dissolved in seawater that may cause scale formation or other adverse effects on RO membranes are removed. It is necessary to remove it as much as possible. This pretreatment requires large-scale equipment such as a filtration device using sand, activated carbon, etc., and a coagulation sedimentation device using chemicals, so the pretreatment cost (
Currently, costs such as equipment costs, chemical costs, electricity costs, etc. have a large impact on water production costs. As mentioned above, in order to perform seawater desalination using an RO membrane in one stage desalination, it is necessary to use an expensive high-performance RQ system with a high desalination rate, but it is necessary to use a two-stage desalination system that repeats the desalination process twice. If desalination process is adopted, RO
Stringent performance demands on the membrane are greatly relaxed.

For example, in order to produce drinking water with a salinity of 500, which is the limit for normal drinking, from average seawater with a salinity of 35,000, one-stage desalination requires a desalination rate of at least 98.6%. Although a high-performance RO membrane is required, an RO membrane with a salt removal rate of % unevenness is sufficient for two-stage desalination. However, even in the two-stage desalination process, energy loss due to the discharge of the high-pressure line cannot be avoided, and in particular, the energy increase required to pressurize the permeated water obtained in the first stage again in the second-stage desalination process is Even if the second stage pline is fed back to the first stage, it cannot be overlooked from an energy saving perspective.

Furthermore, the two-stage desalination process requires the same high pressure and high recovery rate as the one-stage desalination process, which simplifies the competitive seawater pretreatment. I can't afford it. The disadvantage of the above-mentioned seawater desalination method using a secondary RO membrane is the energy loss caused by the discharge of high-pressure brine. The fact that the problem can be almost completely solved by applying this problem is already explained in detail in the patent application ``Rotary Liquid Separator'' filed by the same inventor on May 16, 1974.

If there is no energy loss due to high-pressure line discharge,
When raw water can be used in abundance, such as in seawater or desalination, there is no need to forcefully increase the freshwater recovery rate, and therefore there is no need to use particularly high-performance and expensive RO membranes, and the pressure applied to seawater can be increased more than necessary. There's no need. Therefore, the load on the RO membrane is significantly reduced, and the pretreatment of seawater can be correspondingly simplified. This greatly contributes to reducing the equipment cost and operating cost of the seawater desalination equipment as a whole. As mentioned before, in order to avoid using a particularly high-performance RO membrane, it is sufficient to adopt a two-stage desalination process, but in rotary desalination equipment, these two stages
A staged desalination process is particularly suitable.

The reason for this is that the first-stage separation modules, which require relatively high pressure and require a large number of units, are arranged in the outer layer relative to the rotating shaft, and the second-stage separation modules, which require relatively low pressure and require a small number, are arranged in the inner layer. This is because it makes sense from the perspective of the space of the device and the way centrifugal force is applied. Since two-stage separation modules can be arranged in a rational manner in this way, in rotary desalination equipment, even if a two-stage desalination process is adopted, the space occupied by the equipment and the rotational power must be particularly large. There is no such thing. This is a major advantage of the rotary desalination equipment in terms of equipment costs and operating costs. The object of the present invention is to adopt a multi-stage desalination process in a rotary separation liquid using an RO membrane, and arrange the first separation module stage in the outer layer around the rotation axis and the second separation module stage in the inner layer. This makes it possible to efficiently use the space occupied by the bag counterfeit and the rotational power, and to simplify the pretreatment of seawater by keeping the freshwater recovery rate, desalination rate, and pressure to reasonably low values. To provide a low-cost, energy-saving rotary desalination bag counterfeiter capable of minimizing water generation costs.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 and 2, reference numeral 1 denotes a vertical rotary demineralizer main body, which is radially installed on different radii of the outer circumference of a rotating shaft 3 that is rotatably supported, and has demineralized liquid inlet ports. 9a, 2
7a, concentrated liquid outlet 9b, 27b and permeated water outlet 9c,
27 groups of inner separation modules [second separation module stage] and nine groups of outer separation modules [first separation module stage], each having a built-in inverted horse mackerel permeable membrane having 27c;
An inner annular liquid distribution pipe 24 is provided opposite to each other so as to sandwich the inner separation module 27, and directs the rotating shaft passing through the desalination liquid inlet 27a and concentrated liquid outlet 27b of the inner module. The inner annular liquid collecting pipe 30 and the rotating shaft of the outer separation module, which are provided oppositely to each other so as to sandwich the outer separation module 9, are connected to the desalination liquid inlet 9a and the concentrated liquid outlet 9b. An outer annular liquid distribution pipe 6 and an outer annular liquid collection pipe 12 that surround each other, an inner liquid supply pipe 23 that sends the liquid to be demineralized from the rotating shaft 3 or the vicinity thereof to each of the annular liquid distribution pipes 6 and 24, and an outer A liquid supply pipe 5, an inner liquid drain pipe 31 and an outer liquid distribution pipe 13 for discharging the liquid from each of the annular liquid collecting pipes 12 and 30 from the rotating shaft or the vicinity thereof, a permeated water outlet 9c of each separation module, The outer water collection tank 18 is provided with an inner water collection tank 37 and an outer water collection tank 18 provided in association with the outer water collection tank 27c, and supplies the liquid to be demineralized to the outer separation module group 9, and is separated by the outer separation module group 9.
The permeate collected in the inner separation module 27 is supplied to the inner separation module 27 as a liquid to be desalinated. The rotating shaft 3 has desalinated liquid channels 4 and 22 connected to each liquid supply pipe 5 and 23 on the upper end side, and concentrated liquid paths 14 and 32 connected to each drain pipe 13 and 13 on the lower end side. It is constructed of a double tube and is rotatably attached to a fixed frame 40 via a bearing 39.

The rotational force of the electric motor 44 is transmitted to the rotating shaft by a belt 43 that connects a pulley 41 attached to the rotating shaft and a pulley 42 of an electric motor 44 installed on a fixed frame. The upper end of the inner tube forming the demineralized liquid path, which is the upper end of the rotating shaft, is connected to the permeated water koji supply pipe 19 via the rotary joint 21, with one end connected to the outer water collection tank 18 and with the pump 20 interposed. A raw water tank 2 is provided on the upper outer periphery of the outer tube to accommodate a desalination flow 4 whose bottom is outside, and a raw water tank 2 is provided with a desalination liquid flowing from outside the rotating system. The raw water supply 9 foundation pipe E end is facing. Further, the lower end of the rotating shaft is connected to the outer concentrated liquid path 14 through a rotary joint 15, with one end facing the raw water tank 2, and to a return pipe 34 and an inner concentrated liquid passage 32, a through valve 33, and a pump 35 interposed therebetween. It is connected to a discharge pipe 17 which has a valve 16 as a shell. Next, how to attach the separation module to the rotating shaft will be explained. The group of 9 outer separation modules constituting the first separation module stage is arranged radially around the axis on one radius of the outer circumference of the rotating shaft 3, and each separation module 9 has an outer annular liquid distributing The pipe 6 and the outer annular liquid collecting pipe 12 are connected to each other by pins via attachment arms 7 and 10 which protrude from the outer annular liquid collection pipe 12 and are fixed to both annular spaces. Therefore, these annular tubes 6
and 12 serve as supporting members for the separation module, and as a result, also serve as liquid path forming members. and those annular tubes 6
and 12 are supported by outer liquid supply pipes 5 and 13 which are fixed to the rotating shaft 3 and also serve as support arms. The group of inner separation modules 27 constituting the second stage separation module stage is also supported in the same manner as described above, so a description thereof will be omitted. In addition, 8, 26 are annular liquid pipes 6, 24
and a connecting pipe to which the demineralized liquid inlets 9a and 27a of the separation module are connected, and 37 is associated with an extraction pipe 36 connected to the inside of the outer annular water collection tank 18 and the permeated water outlet 27c of the inner separation module. 38 indicates an inner annular water collecting tank provided outside the rotating system, and 38 indicates a produced water outlet pipe. In addition, the separation modules 9 and 27 are manufactured by the same applicant in 1974.
The plan proposed in Samurai Gan No. 54-60093, filed on May 16, 1983, is a system in which flat plate-shaped separation elements equipped with inverted horse mackerel permeable membranes are stacked in a stacked manner, and an open space through which the liquid to be demineralized passes between the elements is vertically formed. It is preferable to use a laminated flat plate type separation module in which an open space is formed in the horizontal direction and the permeated water is drawn out into each separation element.
Other types may also be used, such as hollow fiber types.

However, in this case, it goes without saying that it is necessary that the inside of the module is not significantly deformed by the action of centrifugal force. In addition, the above-mentioned samurai Isoaki 54-6009
In the module proposed in No. 3, the permeated water was directly discharged outside the rotating system from any point on the outer side of the separation module, but this time, in order to straighten the mulberry water, the nuclear separation module A simple water guide cover is attached to the outer side of the tank, and the released permeated water is guided to the permeated water outlet provided at the lowest part of the outer side.

The operation of the rotary desalination apparatus of the present invention constructed as described above will be explained using an example in which it is used for desalination of seawater in which the liquid to be desalinated is seawater. Seawater, which is the liquid to be demineralized, is led to the raw water tank 2 via the supply pipe 1, and then from the liquid to be demineralized path 4 to the outer liquid supply pipe 5.
The liquid is introduced into the outer annular distribution pipe 6 via the connecting pipe 8 and distributed to each outer separation module 9.

At this time, since each separation module rotates around the rotation axis, the seawater passing through the separation module 9 is pressurized by the action of centrifugal force, and while flowing along the reverse horse mackerel permeable membrane inside the module. Next, the membrane's reverse permeation action classifies salts in seawater and separates pure water, separating it into concentrated seawater with a high salt concentration and permeated water containing a certain amount of salt. The concentrated seawater is collected from the connecting pipe 11 into the outer annular liquid collecting pipe 12, and then the pressure gradually decreases as it moves inside the outer liquid distribution pipe 13 toward the center of the rotating shaft, and then flows through the outer concentrated liquid path 14 of the rotating shaft. 9
When it reaches the E-Qin pipe 17, it holds almost no pressure and is discarded outside the system. On the other hand, the permeated water is discharged outward from the permeated water outlet 9c of the outer separation module, flows down against the annular fixed wall, and is retained in the outer annular water collection tank 18. The above is the first stage desalination step. Next, the permeated water in the outer annular water collection tank of the first stage desalination process is transferred to the demineralized liquid channel 22 inside the rotating shaft by the action of the pump 20 via the permeated water supply pipe 19 installed outside the rotating system. The liquid is supplied to the valley inner separation module 27 via the inner liquid supply pipe 23 and the inner annular liquid distribution pipe 24 and the connecting pipe 26 .

In the separation module, this permeated water is used as a liquid to be desalinated and desalinated in the same way as the desalination action in the first stage desalination step, and the concentrated seawater exits the connecting pipe 28 and flows into the inner annular liquid collecting pipe. 30
One liquid is collected and guided through the inner liquid collecting pipe 31 to the concentrated liquid path 32 inside the rotating shaft. And that concentrated seawater has already reached the first stage.
Since the seawater has undergone stage desalination treatment and has a relatively low concentration, it is returned to the raw water tank 2 via a return pipe 34 installed outside the rotating system, and is again used as the liquid to be desalted in the first stage. On the other hand, the permeated water coming out of the inner separation module is passed through the permeated water outlet 27c of the separation module.
It is discharged into the inner annular water collection tank 37 through a take-out pipe 36 attached to the tank and is retained there. In this way, the second stage desalination step is completed, and water of the desired quality is obtained from the inner annular water collection tank 37, and the water is sent to the utilization system through the produced water extraction pipe 38. In this embodiment, the flow rate of the liquid to be demineralized through each separation module 9, 27 is controlled by valves 16 and 33, but only by pumps 20 and 35, or by the pumps and valves being in phase relation. It can also be adjusted.

The desalination effect in the separation module will be described.

When the rotary shaft 3 is rotated with all liquid paths filled with liquid, the liquid has a pressure in each liquid path that is proportional to the number of rotations and the distance from the rotation axis. In general, the higher the concentration of the liquid to be separated, the higher the pressure required for the membrane separation action, so if the rotating shaft is rotating at a constant rotation speed, the farthest from the axis 0 1 at the position, i.e. the large radius
A second stage separation module is installed, in which the highly concentrated liquid to be demineralized is treated under high pressure, and the permeated water from there is processed at a second stage installed at a small radius at a slightly lower pressure. The desalination process will be carried out using the separation module. Furthermore, if advanced processing is required, the number of separation module stages may be increased using a similar method. As is clear from the above description, the present invention provides the following significant effects.

■ A large number of separation modules are installed on the outer circumference with different rotation axes to form a multi-stage separation module group, and the outer separation module group first desalinates seawater, and the desalinated liquid to be desalinated is transferred to the inner separation module group. Since V is supplied to the separation module group for desalination, optimal seawater desalination can be performed depending on the concentration of the liquid to be desalinated.

■ The outer separation module group can have a larger number of separation modules than the inner separation module group, and the working pressure is higher, so a large amount of seawater can be desalinated in this outer separation module group. By desalinating the desalted permeate with a low salt concentration in the inner separation module, effective desalination can be performed.

3. Since the outer module group and the inner module group are rotated at high speed to apply pressure, there is no need for a boost pump like in the case of secondary modules, and in addition, it is possible to release concentrated liquid with high pressure to the atmosphere like in the conventional method. No need for wasted energy.

■ Inner and outer annular liquid distribution pipes and inner and outer annular liquid collecting pipes are provided at the upper and lower parts of the inner and outer separation module groups on the rotating shaft and the body, and the liquid to be demineralized is routed from the rotating shaft to the inner and outer parts through the annular liquid distribution pipes. Since the concentrated liquid from the internal and external separation module groups is returned to the rotating shaft via the annular liquid collection pipe, the residual pressure of the concentrated liquid discharged outside the system becomes zero, so that separation is possible. Only the pressure drop of the permeated water at the reverse permeation membrane in the module reduces the amount of released energy, resulting in energy savings.Moreover, since the annular liquid distribution pipe and the annular liquid collecting pipe have approximately the same pressure, the pressure drop in the separation module is reduced. The residence time of the desalting solution can be easily adjusted.
■ Since the same separation modules can be used to make up the inner and outer separation module groups, it is easy to detect counterfeits in the desalination equipment.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a rotary desalination apparatus of the present invention, and FIG. 2 is a plan view of the apparatus of FIG. 1. In the figure, 1 is a rotary desalination device, 3 is a rotating shaft, 4, 5, 6 and 8 are outer desalination liquid paths, and 9 is an outer separation module (first
9a is a desalinated liquid inlet, 9b is a concentrated liquid outlet, 9c is a permeated water outlet, 11, 12, 13 and 14 are outer concentrated liquid channels, 18 is an outer collecting channel, and 19 is a 1st stage permeate feed pipe, 22, 23, 24 and 26 are inner desalination liquid paths, 27 is inner separation module (second separation module stage), 27a is desalination liquid inlet, 27b is concentrated liquid intake The outlet 27c is a permeated water outlet, 28, 30, 31 and 32 are inner concentrated liquid channels, 37 is an inner water collection tank, and 38 is a produced water outlet pipe. Figure 1 Figure 2

Claims (1)

[Claims] 1. A plurality of separation modules each having a demineralized liquid inlet, a concentrated liquid outlet, and a permeated water outlet, and each having a built-in reverse permeation membrane, are arranged on the same radius around the outer periphery of a rotatably supported rotating shaft. The separated module groups are arranged in at least two stages on different radii of the rotation axis, and the inner and outer annular liquid distributors supporting the separated module groups are arranged above and below the inner and outer separated module groups. A pipe and an inner and outer annular liquid collecting pipe are provided integrally with the rotating shaft, and the inner and outer annular liquid distribution pipes are connected to the liquid to be demineralized inlet of each of the inner and outer separation modules,
In addition, the inner and outer annular liquid collecting pipes are connected to the concentrated liquid outlet of each of the separation modules, and the liquid to be desalinated is connected to the upper and lower parts of the rotating shaft to supply the liquid to be demineralized to the above-mentioned inner and outer annular liquid distribution pipes. Concentrate channels are formed to collect the concentrated liquid from the annular liquid collection pipes, and water collection tanks are provided to receive the permeated water from each permeated water outlet of the inner and outer separation module groups, and the liquid to be desalinated is collected from the outer side. A rotating shaft that communicates with the annular liquid collection pipe and that supplies the liquid to be demineralized to the liquid path in the rotating shaft and that receives the permeated liquid that has passed through the outer separation module group and communicates the permeated water in the water collection tank to the inner separation module group. A rotary desalination device characterized in that the liquid is supplied to a channel to be desalinated inside.