JPH05169049A - Method and device for injecting solution - Google Patents

Abstract

PURPOSE:To easily inject a chemical without being affected by the ascending flow in a solution tank by dipping a membrane module in a slurry of the chemical, separating a saturated soln. through the module and injecting the soln. into a specified place. CONSTITUTION:This injector consists of a tank 1 contg. a slaked lime slurry, etc., and a process pump 2. An agitator 3 is set in the tank 1, and an external pressure-type membrane module 4 is dipped. The module 4 is connected to the pump 2 through a liq. pipe 5 and further to the injection point from the outlet of the pump 2 through an injection pipeline 6 and an injection valve 7. The pump 2 is started when the soln. is injected, and the saturated soln. of slaked lime is sucked and filtered by the module 4 and supplied to the injection point through the pipeline 5, and the injection valve 7 of the pipeline 6. The amt. of the soln. to be injected is controlled by the speed of the pump 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to industrial chemical injection equipment, and more particularly to chemical injection equipment in water treatment facilities.

[0002]

2. Description of the Related Art A conventional chemical injection facility and solution injection method will be described by taking the field of water purification as an example. In recent years, plans for a post-alkali injection facility for adjusting the pH of tap water have been increasing.
As the alkaline agent used for this, caustic soda, soda ash, slaked lime, etc. are used. The use of slaked lime is superior to the use of other alkalis because it can prevent corrosion of the pipe by forming a coating of calcium carbonate on the inner surface of the pipe and is inexpensive.

However, slaked lime is often used in the form of a slurry because it has a problem of drug scattering when dissolved and its solubility is very low. However, when it is used as a slurry, there is a problem that slaked lime and other precipitates will be generated at the bottom of the water purification pond when it is injected as an alkali after adjusting the pH of tap water. Few. Since the above problems can be solved by injecting slaked lime as a saturated solution, recently, an apparatus for continuously producing a saturated solution of slaked lime has been developed.

As described above, the solubility of slaked lime is much lower than the solubilities of caustic soda and soda ash, and only slaked lime has a solubility inversely proportional to temperature. The saturated concentration of slaked lime is about 0.2%, and in order to prepare a saturated solution, about 500 times as much water as slaked lime is required. An apparatus for producing a saturated solution of slaked lime by utilizing the dissolution behavior of slaked lime includes the following apparatus.

1. By the contact dissolution method by rising water flow. This method is based on the rising velocity of the dissolved water in the dissolution tank.
This is a method in which a slaked lime slurry layer is maintained at a certain level in the tank, and a saturated solution of slaked lime is created by contact with dissolved water passing through this layer. This type of device is one type of sludge blanket type high-speed sedimentation basin, and the slaked lime slurry layer forms the sludge blanket. A representative example of this type is shown in FIGS.

The type shown in FIG. 2 is an apparatus used as a small-capacity type.
More slaked lime slurry is supplied, and dissolved water is supplied from the water supply pipe 14. A blanket layer 17 is provided in the middle of the dissolution tank 12.
Is generated, and the solution passing through this layer becomes a saturated solution of slaked lime during the passage and is taken out from the solution outflow pipe 15. Drain valve that contains undissolved slaked lime and insoluble matter 1
It is discharged from 6. In this device, the slaked lime slurry is intermittently supplied.

The type shown in FIG. 3 is a device used as a large-capacity type, and the names and functions of each element of the device are the same as those of the device shown in FIG. In the apparatus shown in FIG. 3, sludge containing undissolved slaked lime can be taken out from the sludge drawing pipe 18 and recovered to be regenerated as slaked lime slurry. Further, in the case of this apparatus, the slaked lime slurry may be supplied either continuously or intermittently.

In the rising water flow system, in order to maintain the slurry zone, the supply of the slaked lime slurry is often continuous, and therefore the factors that need to be controlled are the two factors, the supply of the slaked lime slurry and the supply of the dissolved water. .. Further, since the slurry zone is maintained by the rising water flow, the rising flow velocity is limited. If the rising water flow is too small, the slurry will settle and the zone cannot be maintained. On the contrary, if the rising water flow is too high, there is a risk that all the slurry will carry over.

Therefore, the rising flow velocity is generally 40 to 10
The range is 0 mm / min, and the supply amount of dissolved water is limited to this range. Further, when restarting after the operation is stopped, the slurry is settled at the bottom, and it takes time to form a normal slurry zone. As described above, the rising water flow system has a drawback that the operation management is difficult and the injection control range is narrow.

2. With a stirring contact method using a stirrer. This system is composed of a dissolution tank and a stirrer, and mechanical energy is applied to water by the stirrer to dissolve the water.
A representative example of this type is shown in FIG.

In FIG. 4, slaked lime is batchwise charged into and stored in the dissolution tank 19 through the inlet 21, and water corresponding to the required saturated slaked lime solution is supplied to the water supply pipe 2 below the dissolution tank 19.
0 to supply a slaked lime slurry layer 25 by stirring with a stirrer 23, and further supply water to raise the dissolved solution at a low speed to overflow the saturated solution from the upper part of the tank and take it out from the solution outflow pipe 22. .. The drain containing undissolved slaked lime and insoluble matter is discharged from the drain valve 24.

[0012] In this method, since the injection of slaked lime is carried out in batches, it is only necessary to control the supply amount of the dissolved water, and therefore maintenance is easy. However, in order to obtain a saturated solution, the rising flow velocity in the tank needs to be about 1/10 of that in the rising water flow system. Therefore, the capacity per unit area of the dissolution tank is 1/1 of that of the rising water flow system.
0, in other words, the installation area is required 10 times. For this reason, there is a drawback that a very large space is required as the processing amount increases.

The facility for producing a saturated solution described above using slaked lime as an example can be applied to the production of a saturated solution of another chemical. It is particularly useful for the preparation of saturated solutions of chemicals where the solubility is low and the solubility is inversely proportional to temperature, as is the case with the dissolution of slaked lime. However, in both conventional methods, the rate of saturated solution generation is limited by the rising flow rate of the solution in the dissolution tank,
Since the production speed is slow, a large-scale device is required for high-volume production, and therefore a large space must be prepared for the device. Further, since it is necessary to control the rising flow rate of the solution, it is necessary to provide a control device and other auxiliary equipment for stable production, which makes the device complicated and expensive.

[0014]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems in the above solution injection method and solution injection device for chemicals, and to provide a solution injection method which is easy to operate without being affected by the rising flow velocity in the dissolution tank. The injection device provided is to be compact and simple in construction.

[0015]

The above problems can be solved by developing an injection method and an injection apparatus of the present invention.

That is, 1) In the step of injecting a chemical into a predetermined injection location, the membrane module is immersed in a slurry of the chemical, the saturated solution is separated through the membrane module, and injected into the predetermined injection location. A method for injecting a solution, comprising:

2) In an injection device for injecting a chemical into a predetermined injection place, the injection device has at least a slurry tank,
A solution injecting apparatus comprising: a membrane module immersed in the slurry tank and a treatment pipe communicating with the membrane module.

3) In the solution injecting step described in 1) above, a treatment pump is connected to the treatment pipe communicating with the membrane module, and the treatment pump is used to separate and inject the saturated solution and to wash the membrane module. A solution injection method that is also used.

4) The solution injecting device as described in 2) above, wherein a process pump that is rotatable forward and reverse is connected to the process pipe communicating with the membrane module. A method for injecting a solution, which comprises separating and injecting a saturated solution through an external pressure type membrane module immersed in a slurry.

The method and apparatus of the present invention is a production method in which the formation of a saturated solution is not affected by the rising flow rate of dissolved water, and is based on the novel idea of filtering the slurry. It uses a membrane.

In the present invention, the term "slurry" means a state in which a drug is dissolved in water and coexists with a saturated or near-saturated solution and contains undissolved and undissolved substances. Also,
The slurry tank means a tank containing slurry. Furthermore, the injection method and the injection device are not simply the method of injecting the solution and the device used therefor, but the saturated solution is filtered and separated from the slurry through the membrane module, and then the solution is sent to the destination. , A method of injecting at the point of use (injection point), and a device that exhibits these functions.

The method of directly filtering and purifying a solution using a membrane and injecting the solution at the point of use (injection point) is a conventional method, but it is a slurry for the purpose of always obtaining a solution having a saturated concentration. There is no other example that adopts the method of dipping the membrane module inside.

As the membrane to be used, in the case of the above-mentioned slaked lime, the pore size of the membrane is MF grade, but UF grade or the like is appropriately selected according to the application. The material of the membrane is selected to be suitable for the properties of the chemical to be filtered. For example, in the case of slaked lime, an alkali resistant film is required, and preferably a ceramic film.

In the present invention, it is preferable to use an external pressure type membrane module in an open dissolution tank, and at this time, it is preferable to generate a filtration pressure by a suction type. That is, the treatment solution of the external pressure type membrane module, for example, a saturated slaked lime solution from the slaked lime slurry, in the case of flowing out from the treatment pipe communicating with the membrane module, connect a suction pump to the treatment pipe, the saturated solution by the suction pump. Is to be filtered out.

A further feature of the present invention is that when a pump capable of exerting not only a suction function but also a pressurizing function is used as the pump, water is sent from the inside of the external pressure type membrane module using this pump. It is possible to clean the module with water or a solution. As a pump that can exert not only the suction function but also the pressurizing function, for example, a positive displacement screw pump can be mentioned. Since this positive displacement screw pump further has a function as a metering pump, there is an advantage that the processing solution can be quantitatively filtered, liquid-fed and injected.

Although there is a method of cleaning the membrane by air cleaning, it is not preferable because the solute may be deposited on the surface of the membrane due to bubbling by air in the membrane filtration step in which the saturated solution is handled. In this case, from the inside of the membrane module. It is preferable to wash with a liquid such as water.

The advantages of the solution injection method and apparatus of the present invention are summarized below. In the present invention, since the saturated solution is taken out from the slurry by filtration using the membrane, there are restrictions such as the need to delicately control the rising flow rate of the liquid in the slurry tank in order to take out the saturated solution as in the conventional method. No conditions,
Further, since the chemicals are charged into the slurry tank by a batch method, the solution injection method of the present invention is easy to operate and it is extremely easy to operate and maintain the apparatus. When, for example, a positive displacement screw pump is used as the driving force of the present invention, a wide range of solution can be injected by controlling the rotational speed of the pump.

Further, according to the method of the present invention, the concentration of the solution charged in the slurry tank can be increased, so that the volume of the dissolution tank used can be reduced. By using a multi-function pump such as a positive displacement screw pump as the processing pump, not only filtration and injection but also cleaning of the membrane module can be performed with one pump, so that the apparatus can be simplified.

Therefore, the solution injection method of the present invention has many advantages such as easy operation, simple apparatus, small installation space, and low cost. INDUSTRIAL APPLICABILITY The solution injection method and injection apparatus of the present invention are particularly suitable as a solution injection method and injection apparatus for chemicals having low solubility and whose solubility is inversely proportional to temperature, but limiting the symmetry of application only to chemicals. is not.

[0030]

EXAMPLE A concrete example of the injection device of the present invention is shown in FIG.
The present invention will be described by taking slaked lime as an example of the chemicals to be handled and dealt with, but the following description is not intended to limit the present invention.

(Embodiment 1) In FIG. 1, an injection apparatus comprises a slurry tank 1 suitable for slaked lime slurry and a processing pump 2. A stirrer 3 for preventing sedimentation of the slurry is installed in the slurry tank 1, and an external pressure type membrane module 4 is immersed in the slurry tank 1. The membrane module 4 is connected to the processing pump 2 via a liquid supply pipe 5, and is further connected to an injection point via an injection valve 7 from an outlet of the processing pump 2 through an injection pipe 6.
Further, the injection pipe 6 from the outlet of the processing pump 2 is connected to the injection valve 7
In front of the water supply pipe, it becomes a water supply pipe 8 and is connected to a water supply tank via a water supply valve 9. A drain valve 11 is installed in the lower part of the slurry tank 1 to discharge the non-dissolved matter in the slaked lime.

The forward rotation, the reverse rotation and the rotation speed of the processing pump 2 can be controlled by a signal from the rotation speed controller 10. In the present embodiment, since the processing pump 2 is a positive displacement screw pump, it can be rotated in the normal direction and the reverse direction, and the injection amount can be adjusted by controlling the rotation speed.

The concentration of the slaked lime slurry in the slurry tank 1 is set to about 0.5 to 5%. Here, the concentration of the slaked lime slurry is a concentration containing undissolved slaked lime, and when this slurry is filtered, the treatment solution becomes a saturated solution of slaked lime. The slaked lime may be added to the slurry tank 1 in the form of slurry or powder. After the input slaked lime is dissolved in the slurry and the slurry tank 1 is filled with the slaked lime slurry, the stirrer 3 is operated to prevent the slurry from settling. Next, the processing pump 2 is started to suction-filter the slaked lime saturated solution from the membrane module 4, and the solution is sent to the injection point through the processing pipe 5 and the injection valve 7 of the injection pipe 6. The injection amount is controlled by controlling the rotation speed of the processing pump 2.

The treatment is continued, and the cleaning is started when the suction pressure of the membrane rises to the set value. For cleaning, close the injection valve 7,
After opening the water supply valve 9, reverse the processing pump 2 and
Fresh water is passed through the membrane module 4. The amount of washing water is controlled by controlling the rotation speed. By this washing, clear water is passed from the inside of the membrane to the outside, and the slaked lime adhering to the surface of the membrane is peeled off.
Not only the exfoliated slaked lime but also the used washing water is reused as the dissolved water of the slaked lime.

When the treatment is continued and the water level in the slurry tank 1 is lowered to some extent, the slurry tank 1 is replenished with water. When this is repeated, the slurry concentration in the slurry tank 1 becomes thin, and when it becomes approximately 0.5%, new slaked lime is added.

[0036]

The solution injection method of the present invention utilizes a membrane,
Since the saturated solution is taken out from the slurry, there are few factors to control and it is easy to operate. The solution injection device of the present invention is
An external pressure type membrane module is installed by immersing it in a slurry tank, and the membrane module is connected to a treatment pump that can be rotated in the forward and reverse directions through a treatment pipe, enabling filtration and injection as well as cleaning, thus simplifying the device structure. It does not take up a lot of installation space, and thus can be an inexpensive device.

[Brief description of drawings]

FIG. 1 is a flow chart of a solution injection device according to the membrane filtration method of the present invention.

FIG. 2 is a cross-sectional view of an example of a dissolution apparatus by a contact dissolution method using rising water flow.

FIG. 3 is a cross-sectional view of another example of a dissolution apparatus by a contact dissolution method using rising water flow.

FIG. 4 is a dissolution apparatus 1 by a stirring contact method using a stirrer.
Sectional view of the example.

[Explanation of symbols]

 1 Slurry Tank 2 Processing Pump 3 Stirrer 4 Membrane Module 5 Processing Pipe 6 Injection Pipe 7 Injection Valve 8 Water Supply Pipe 9 Water Supply Valve 10 Rotation Speed Controller 11 Drain Valve 12 Dissolution Tank 13 Slurry Supply Pipe 14 Water Supply Pipe 15 Solution Outflow Pipe 16 Drain Valve 17 Blanket layer 18 Sludge extraction pipe 19 Dissolution tank 20 Water supply pipe 21 Input port 22 Solution outflow pipe 23 Stirrer 24 Drain valve 25 Slurry layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display C02F 1/66

Claims (4)

[Claims] 1. A step of injecting a chemical into a predetermined injection place, immersing the membrane module in a slurry of the chemical,
A method for injecting a solution, which comprises separating a saturated solution through the membrane module and injecting it into a predetermined injection site. 2. An injection device for injecting a chemical into a predetermined injection place, the injection device including at least a slurry tank, a membrane module immersed in the slurry tank, and a treatment pipe communicating with the membrane module. A solution injection device characterized by being provided. 3. The solution injecting step according to claim 1, wherein a treatment pump is connected to a treatment pipe communicating with the membrane module, and the treatment pump is used to separate and inject a saturated solution and to wash the membrane module. A solution injection method that is also used. 4. The solution injection device according to claim 2, wherein a process pump that is rotatable forward and reverse is connected to the process pipe communicating with the membrane module.