JPS5922600B2 - Control method and device for heat transfer fluid for freezing and thawing sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling a heat transfer liquid for freezing and thawing sludge, and more specifically, for controlling a heating medium liquid when freezing and thawing sludge, and more specifically, for controlling when the operating body of a sludge freeze-thaw treatment apparatus is stopped and for energizing this apparatus. The present invention relates to a heat transfer liquid control method and apparatus for freezing and thawing sludge, which consists of allowing the cooling heat transfer liquid to flow freely without blocking the cooling heat transfer liquid circulation circuit when the power is cut off.

Various difficult problems have been exposed in the dewatering treatment of hydrated sludge as industrial waste.

In other words, this type of sludge generally exhibits colloidal properties in which sludge particles as a solid content and water are closely combined with each other, so that it can be processed using conventional filtration methods, centrifugal dehydration methods, heat drying methods, etc. In this process, it was difficult to completely separate water from sludge.

However, this technical problem is that if the water-containing sludge is cooled and frozen to solidify it, and then this frozen sludge is heated and thawed, the particles of the sludge itself become coarse, and therefore have extremely good sedimentation properties. The so-called freeze-thaw method (for example, Japanese Patent Publication No. 36-18442
This problem has already been solved by the above publication.

Therefore, the patent applicant has typically proposed a "sludge water separation device" (Japanese Patent Publication No. 19187/1987), a "sludge freeze-thaw device" (Japanese Patent Publication No. 19187/1987), and a "sludge freeze-thaw device" (Japanese Patent Publication No. 19187/1987) as devices for suitably implementing the freeze-thaw method.
We have filed various patent applications, including Japanese Patent Application No. 158474/1983.

The latter ``sludge freeze-thaw device'' basically consists of a heat transfer device consisting of a compressor, a condenser, and an evaporator, a pair of freeze-thaw tanks equipped with a radiator, and this freeze-thaw tank. and a heat medium liquid pipe that thermally connects the heat transfer device to the heat transfer device. In particular, in this device, the heat transfer device has a primary condenser connected to an external water supply system separately from a normal condenser. This allows for a good heat exchange balance between heat radiation and heat absorption during the refrigeration cycle, allowing start-up operation without overloading the compressor even when one side of the freeze-thaw tank does not accommodate the thawing load. The effect of ensuring the cycle has been successfully achieved.

However, in this type of sludge freezing and thawing equipment, the switching valve for alternately introducing the cooling heat medium liquid and the heating heat medium liquid into the freezing and thawing tank is usually a solenoid valve. Moreover, this solenoid valve has a structure that closes when power is lost, and as a result, the following problems have been found to exist.

That is, when the heat transfer liquid switching valves constituted by electromagnetic valves are no longer energized due to power loss, all of the switching valves are closed.

For this reason, the heat medium liquid is trapped between the switching valve and the check valve provided on the discharge side of the heat medium liquid supply pump and within the radiator.

Normally, the heat transfer fluid pipes and the freeze-thaw tank are kept cool, but as mentioned above, if the entire sludge freeze-thaw treatment equipment is in a suspended state and the outside temperature rises during that shutdown period, the heat transfer fluid will be insulated. The heat medium liquid blocked in the liquid pipes and the radiator expands, and the internal pressures of the pipes and the radiator increase abnormally.

In particular, when the equipment is stopped for a long period of time, or when the outside temperature rises rapidly even for a short period of time such as in the summer, the pressure inside the pipes and the pressure inside the radiator can rise by as much as 8 to 9 kgZcd. There was also concern that this could cause an accident that could damage the evaporator or the radiator installed in the freeze-thaw tank.

In order to prevent such accidents from occurring, for example, (1) the inlet and outlet sides of the freeze-thaw tank for cooling heat transfer liquid are connected by a bypass pipe using pilot piping to prevent the pressure inside the pipe from rising; The structure is designed to allow the heat transfer liquid to escape to the outlet side via the safety valve.

(2) In order to reduce the pressure of the cooling heat medium liquid in the heat medium liquid pipe line by escaping, a safety valve is provided in a small pipe leading to the discharge side of the heat medium liquid supply pump and this small pipe.

(3) A method has been considered in which a double solenoid is used in the switching valve so that even in the event of power loss, the open/closed state of the switching valve is maintained in the state at the end of the operation of the device.

However, the above method has the disadvantage that the piping or control mechanism becomes complicated, and cannot necessarily be said to be practical.

Therefore, as a result of repeated efforts and trial production, the inventors of the present invention used an electromagnetic valve that opens when electricity is applied as a switching valve for the heating heat medium liquid in the above device, while switching the cooling heat medium liquid. If you use a solenoid valve that closes when the valve is energized, and open the switching valve related to the cooling heat medium liquid when the solenoid valve loses power, the cooling heat can be removed without using a bypass pipe or safety valve. It has been found that the liquid medium can freely flow through the pipes and the radiator, and therefore, the above problems can be solved at once.

Therefore, the general object of the present invention is to introduce a heating medium liquid into the freezing/thawing tank alternately under the action of a switching valve to freeze and thaw the sludge stored in the freezing/thawing tank. It consists of a solenoid valve that opens when the switching valve loses power, and prevents the cooling heat medium liquid from being trapped in the heat medium liquid pipes or the radiator when the equipment is inactive. It is an object of the present invention to provide a method and apparatus for controlling a heat transfer liquid for freezing and thawing sludge, which can prevent damage to vessels.

In order to achieve the above object, in the present invention, the heat transfer liquid flowing through the pipe is cooled and heated, respectively, by an evaporator and a condenser constituting the heat transfer device, and the heat transfer liquid that is cooled and heated in this way is cooled and heated. A method for freezing and thawing sludge in a pair of freeze-thaw tanks by separately and alternately introducing a heat transfer liquid into a radiator disposed in a pair of freeze-thaw tanks under the action of a switching valve, A solenoid valve that opens when the power is shut off is used as a switching valve for the cooling heat medium liquid, while a solenoid valve that closes when the power is shut off is used as a switching valve for the heating heat medium liquid, and a freeze-thaw treatment device is attached. When the power supply for cooling is cut off, the switching valve for the cooling heat medium liquid is opened to communicate the cooling pipe line and the radiator, and the cooling heat medium liquid is transferred to the cooling pipe line and the radiator. It is characterized in that it is allowed to flow freely and the switching valve for the heating heat medium liquid is closed to close the heating heat medium liquid in the heating pipe line.

Note that this method includes a heat transfer device including a compressor, a condenser, and an evaporator, a heating liquid tank that is thermally coupled to the condenser and heats a heat transfer liquid, and a heating liquid tank that is thermally coupled to the evaporator. A cooling liquid tank that is coupled to cool the heat transfer liquid, and a radiator are provided, into which the heat transfer liquid in the heating liquid tank and the cooling liquid tank are introduced separately and alternately under the action of a switching valve. In a sludge freeze-thaw treatment apparatus comprising at least a pair of freeze-thaw tanks, a switching valve for introducing the cooling heat medium liquid into the radiator is a solenoid valve that is opened when the power is cut off, and a switching valve for introducing the cooling heat medium liquid into the radiator is configured to be a solenoid valve that is opened when the power is cut off. This method is suitably implemented by a control device for a heat transfer liquid that freezes and thaws sludge, characterized in that the switching valve introduced into the radiator is an electromagnetic valve that is closed when the power is shut off.

Other objects and advantages of the present invention will become more apparent from the detailed description below.

Next, the method of controlling a heat transfer liquid for freezing and thawing sludge according to the present invention will be described in detail below with reference to the accompanying drawings, giving preferred examples in relation to the apparatus for carrying out the method. .

In FIG. 1, reference numeral 10 designates a heat transfer device;
This heat transfer device 10 includes a compressor 12, a primary condenser 14,
Basically, the secondary condenser 16, the liquid receiver 18, and the evaporator 20 are connected in circulation via a pipe line 22, respectively.

The secondary condenser 16 and the evaporator 20 are configured to be thermally connected to a heating liquid tank 24 and a cooling liquid tank 26 as buffers for the heat source, respectively, through heat medium liquid pipes 28 and 30. .

On the other hand, these heat transfer liquid pipes 28.30 are connected to the heat radiator 32.30.
34.

That is, the radiators 32 and 34 are made of pipe members wound around the inner walls of freeze-thaw tanks 36 and 38 for storing water-containing sludge and subjecting it to freeze-thaw treatment, and the ends of these pipe members are respectively It is branched into two branches and connected to the heat medium liquid pipes 2B and 30 via a switching valve VH2VC and a branch circuit.

Note that the switching valve VH refers to a valve disposed in a branch pipe of the heat medium liquid pipe line 28 connected to the heating liquid tank 24, and the switching valve VC refers to a valve disposed in a branch pipe of the heat medium liquid line 28 connected to the heating liquid tank 24. This refers to a valve installed in a branch pipe of the liquid pipe line 30.

Further, since four branch pipes are led out from each of the heat medium liquid pipes 28 and 30, the switching valve VHt, reference numeral VHtt, consists of four valves with vL2>■H21tvH2□; The switching valve VC has the reference symbol ■C
11, ■C02, vC21゜VC22 It is composed of four valves, especially the switching valve VHII according to the present invention.
, VH12, VH21O and VH2□ are equipped with solenoid valves that open when energized, and a switching valve VC10 is used.
, VC1□, VC2, and VC2□ are equipped with solenoid valves that close when energized.

In the figure, reference numeral 40 indicates a circulation pump installed in the heat medium liquid pipe line 28, and reference code 42 indicates a circulation pump installed in the heat medium liquid line 30.

Further, reference numerals 44 and 46 indicate the circulation pump 40.
．． 420 shows check valves installed on the discharge side.

Therefore, when the heat transfer device 10 is energized to forcibly circulate the refrigerant made of freon, ammonia, etc. in the pipe line 22 under the action of the compressor 120, the refrigerant is evaporated under the evaporation action of the evaporator 20. , cooling the heat transfer medium in the conduit 30, that is, the cold brine.

The cold brine cooled in this way is passed through the circulation pump 42.
Circulation is carried out in the pipe line 30 by the forced circulation action of the switching valves VH, and ■H2□
is closed, and on the other hand, the switching valves VC□1 and vC2□ are opened, so that the sludge flows into the radiator 32 in the freeze-thaw tank 36 and freezes the sludge stored in the freeze-thaw tank 36.

Further, the heat medium liquid, that is, the hot brine circulating through the pipe line 28 under the action of the circulation pump 40 is heated by the secondary condenser 16, the switching valves VC1□ and vC2□ are closed, and the switching valves VH□2 and When VH2□ is opened, it flows into the radiator 34 and melts the frozen sludge in the freeze-thaw tank 38.

After a certain period of time has elapsed and the thawing process is completed, the sludge is discharged to the outside from a lower end opening (not shown) of the freeze-thaw tank 38.

Next, fresh sludge for freezing is fed into this freeze-thaw tank 38, and the switching valves VH10, VH21, VC1, and ■C2□ and the switching valves VC1□, vC2□, vH1□
By reversing the opening and closing states of the tank and VH2□, the sludge introduced into the freeze-thaw tank 3B is frozen, and the sludge already frozen in the freeze-thaw tank 36 is thawed.

Figure 2 shows the freezing curve for each cycle of sludge subjected to freeze-thaw treatment in this way.
In order to achieve complete freezing, it is important to cool the cold brine to about -20'C.

The sludge freeze-thaw treatment equipment configured as described above has a 3-hour or 4-hour batch-type freeze-thaw cycle. ) is completed, the operation may be stopped, or the entire device may fall into a dormant state due to some kind of accident.

In such a situation, the present invention operates as follows.

First, during the freezing operation of the freeze-thaw tank 36, the switching valves VC, 1 and vC21, which are closed in the energized state, are not energized, and therefore, both of the switching valves are opened.
On the other hand, the switching valves vH11 and vH2□, which are opened in the energized state, are not energized either, and therefore both of the switching valves are closed.

Eventually, the cold brine reaches the switching valve vC21 from the switching valve VC,1 via the radiator 32, and is finally introduced into the pipe line 30.

Therefore, if the power supply is lost, the switching valves vC11 and vC2□ will maintain their open states, and the switching valves vH1 and vH21 will of course not be energized, so they will not be closed. The state remains unchanged.

Therefore, the pipe line 30 and the radiator 32 are kept in communication with each other by the switching valves vC1□ and VC2□, which are kept open, and the cold brine is connected to the pipe line 30 and the radiator 3.
It becomes possible to circulate freely between the two.

On the other hand, in the freeze-thaw tank 38 which is subjected to the thawing action while the freeze-thaw tank 36 is in the freezing action, the switching valves vH1□ and vH22 are opened when the electricity is on, and the switching valves vC1 and vH22 are opened when the electricity is on. vC2□
is closed, thus introducing warm brine into the radiator 34.

Therefore, when the power is cut off as described above, the switching valve VH
, and vH22 are closed, and the switching valves vC1□ and vC2□ are opened, so that the warm brine is blocked in the pipe line 28.

The operation of such a switching valve is summarized in the table below.

According to the present invention, as described above, even if the sludge freezing and thawing device is in a suspended state, by opening the freezing switching valve, the cold brine in the heat transfer liquid pipe or the radiator can freely flow without being trapped. Let it pass.

Therefore, it has become possible to avoid risks such as damage to the pipe line due to pressure increase in the cold brine circuit without using a bypass pipe or a safety valve.

Moreover, if a switching valve for both cold brine and hot brine is used that closes when electricity is applied, there is a risk that the cold brine and hot brine will mix when the equipment is stopped. Even if the operation is stopped, the warm brine remains closed, so there is no concern about the brine getting mixed in, and the present invention has advantages such as simple and reliable control. Although the present invention has been described with reference to a preferred embodiment, the present invention is not limited to this embodiment, and it goes without saying that various improvements and design changes can be made without departing from the spirit of the present invention. .

[Brief explanation of drawings]

FIG. 1 is a system diagram of a sludge freeze-thaw treatment apparatus according to the present invention, and FIG. 2 is a characteristic curve diagram showing the correlation between sludge temperature and sludge freezing cycle elapsed time. 10... Heat transfer device, 12... Compressor, 14... Primary condenser, 16... Secondary condenser, 18... Curved liquid receiver vessel, 20... evaporator,
22...Pipeline, 24. Heating liquid tank, 26..
... Cooling liquid tank, 28 ... Heat medium liquid pipe line, 30
... Heat medium liquid pipe line, 32 ... Heat radiator, 3
4... Heat radiator, 36... Freeze-thaw tank,
38... Freeze-thaw tank, 40... Circulation pump, 42... Circulation pump, 44...
...Check valve, 46...Check valve.

Claims (1)

[Claims] 1. A heat transfer device in which an evaporator and a condenser that constitute a heat transfer device cool and heat a heat medium liquid flowing through a pipe, respectively, and switch the heat medium liquid that has been cooled and heated in this way. A solenoid valve that is opened when power is cut off, in a method for freezing and thawing sludge in a pair of freeze-thaw tanks by introducing the sludge separately and alternately into a radiator disposed in a pair of freeze-thaw tanks under the action of the valve. is used as a switching valve for the cooling heat medium liquid, and a solenoid valve that closes when the power is cut off is used as a switching valve for the heating heat medium liquid, so that when the power supply that energizes the freeze-thaw processing equipment is cut off. When
The switching valve for the cooling heat medium liquid is opened to communicate the cooling pipe line and the radiator to allow the cooling heat medium liquid to freely flow through the cooling pipe line and the radiator. 1. A method of controlling a heat transfer liquid for freezing and thawing sludge, comprising closing a switching valve for the heat transfer liquid to close the heat transfer liquid in a heating pipe. 2. A heat transfer device including a compressor, a condenser, and an evaporator, a heating liquid tank that is thermally coupled to the condenser and heats a heat medium liquid, and a heating liquid tank that is thermally coupled to the evaporator and heats a heat medium liquid. At least a pair of freeze-thaw devices comprising a cooling liquid tank for cooling the liquid and a radiator, into which the heating liquid tank and the heating medium liquid in the cooling liquid tank are introduced separately and alternately under the action of a switching valve. In the sludge freezing and thawing treatment equipment comprising a tank, a switching valve for introducing the cooling heat medium liquid into the radiator is constituted by an electromagnetic valve that is opened when the power is cut off, and a switching valve for introducing the heating heat medium liquid into the radiator. A control device for a heat transfer liquid for freezing and thawing sludge, characterized in that the switching valve is constituted by an electromagnetic valve that closes when the power is cut off.