JPH0786356B2 - Canned motor pump for absorption refrigerator - Google Patents

Description

The present invention relates to an improved canned motor pump for an absorption refrigerator.

[Conventional technology]

Generally, as shown in FIG. 4, an absorption chiller uses two pumps, one for supplying a high-temperature absorbing solution and one for supplying a low-temperature absorbing solution, as a circulation pump for an absorbing solution (for example, an aqueous solution of lithium bromide). Consists of That is, in FIG. 4, reference numeral 10 is a high temperature regenerator, 12 is a low temperature regenerator, 14 is a condenser, and 16 is a condenser.
Is an evaporator, and 18 is an absorber. The low-temperature regenerator 12 supplies the high-temperature regenerator 10 with the absorption liquid via the high-temperature absorption liquid supply pump 20, and the absorber 18 supplies the low-temperature regenerator 12 with a low temperature. The absorption liquid is transferred via the absorption liquid supply pump 22. The high temperature regenerator 10 and the absorber 18 are connected to each other in communication with each other, and the high temperature liquid obtained in the high temperature regenerator is used to discharge the high temperature absorbing liquid and the low temperature absorbing liquid supplying pump 20. High-temperature heat exchanger 24 for each of the 22 discharge pipes
And the low-temperature heat exchanger 26 are crossed.

However, in the high temperature regenerator 10, the aqueous solution of lithium bromide which has absorbed the refrigerant (water) is supplied. The heating action of the high-temperature steam vaporizes the refrigerant (water) to generate water vapor. This water vapor flows into the condenser 14 through the pipe 28 that is inserted through the low temperature regenerator 12. The water vapor introduced into the condenser 14 is liquefied into water by the cooling action of the cooling water and supplied to the evaporator 16. In the evaporator 16, water is circulated and dispersed by the circulation pump 30 to remove the latent heat of vaporization from the surroundings,
It produces a freezing effect.

The water vapor vaporized by the evaporator 16 is supplied to the absorber 18, where it is absorbed by the highly concentrated aqueous solution of lithium bromide bromide.
The diluted lithium bromide aqueous solution that absorbs water vapor is supplied to the low temperature regenerator 12 by the pump 22. In this low temperature regenerator 12, due to the high temperature steam supplied through the pipe 28,
The low-concentration lithium bromide aqueous solution is heated, and the water in the aqueous solution partially evaporates. Then, the lithium bromide solution is pumped
It is returned to the high temperature regenerator 10 by 20 and the refrigeration cycle described above is repeated again.

By the way, the absorption liquid circulation pumps of the absorption refrigerator thus configured are used under the conditions of high vacuum and low NPSH, respectively. Therefore, under such a condition, the canned motor pump is usually preferably used.

In this case, according to the standard canned motor pump, a part of the pump handling liquid (absorption liquid) is introduced into the front motor chamber of the canned motor through the through hole formed in the rear wall of the impeller in the pump chamber. This liquid lubricates the bearings and guides this liquid from between the rotor and the stator to the rear rotor chamber, which lubricates the rear bearings and then sucks the pump chamber through the liquid passage provided in the rotor shaft. It is circulated to the side to cool the canned motor part and lubricate the rotating part.

However, as described above, in a canned motor pump that handles absorption liquid that is relatively easily vaporized, since the liquid easily evaporates when the pressure is released, for example, the pumped liquid that is introduced into the front rotor chamber of the canned motor. When it is guided to the rear rotor chamber through the rotor / stator, it vaporizes and it becomes difficult to circulate it to the suction side to the pump chamber. Therefore, the rear rotor chamber and the vapor zone of the liquid supply tank that is communicatively connected to the suction side of the pump are connected by piping to transfer the liquid vaporized in the rear rotor chamber to the liquid supply tank. Generally called reverse circulation method) is adopted.

[Problems to be Solved by the Invention]

However, according to the standard canned motor pump used as the above-mentioned conventional absorption liquid circulation pump, two canned motor pumps are used, and a required amount of liquid to be handled is required as a circulating flow inside the canned motor in each pump. Therefore, there is a drawback that the refrigerating efficiency is lower than the amount of the absorbing liquid used.

In addition, each canned motor pump is used under high vacuum, and since the absorbing liquid cools the canned motor and heats itself, the heated liquid passes through the liquid passage provided in the rotor shaft and flows into the pump chamber. In the process of circulating to the suction side, the pressure becomes low, and as a result, the pump is operated under the condition that cavitation is likely to occur.

Therefore, if the reverse circulation method is adopted, the pump handling liquid will have a transient flow inside the canned motor, but since separate piping is required and the pump handling liquid is returned to the liquid supply tank, Similarly, efficiency is reduced.

Further, in the conventional canned motor pump, a balance hole is provided in the impeller in order to balance the shaft thrust, and the liquid flowing through this balance hole circulates, which becomes the internal leakage amount of the pump and improves the pump efficiency. There is a difficulty to reduce.

Therefore, the object of the present invention is to share a canned motor.
With a continuous pump structure, the amount of liquid in the internal circulation flow of the canned motor can be reduced, the internal pressure can be maintained high to prevent cavitation, and the axial thrust balance can be properly maintained without providing a balance hole. (EN) It is possible to provide a canned motor pump for an absorption refrigerating machine which can be manufactured at low cost and has excellent pump efficiency.

[Means for explaining issues]

The absorption chiller canned motor pump according to the present invention,
Impellers are installed in opposite directions on both ends of the canned motor with the rotor shaft as a common shaft, and a pump section with a high head and a pump section with a low head are configured and arranged, and the pump handling liquid is supplied from the discharge side of the pump section with a high head. Is introduced into the canned motor portion and the introduced liquid is caused to flow out to the discharge side of the low head pump portion.

In the above canned motor pump for absorption type refrigerator,
The pump section with high head is connected to the pipe that supplies the absorbing liquid from the low temperature regenerator of the absorption chiller system to the high temperature regenerator, and the pump section with low head is absorbed from the absorber of the absorption chiller system to the low temperature regenerator. It is suitable to connect to a pipe for supplying the liquid.

Further, an inducer for improving the suction performance can be attached to the suction side of each impeller in the high lift pump section and the low lift pump section.

Furthermore, the suction pipe part and the discharge pipe part of the high head pump part are connected to each other by welding, and the suction pipe part and the discharge pipe part of the low head pump part are connected to and separated from each other by a fastener via a flange. By connecting, the pump efficiency can be improved.

[Action]

According to the canned motor pump of the absorption chiller according to the present invention, the canned motor unit is shared, and a pump unit with a high head and a pump unit with a low head are provided at both ends of the canned motor unit.
A canned motor pump including a continuous pump can be configured. In this case, a part of the pump handling liquid supplied to the canned motor part is made to flow from the discharge side of the pump part of high head to the discharge side of the pump part of low head, thereby increasing the internal pressure in the canned motor part. Can hold,
It is possible to effectively prevent the occurrence of cavitation and improve the pump efficiency. Further, in the double pump, by arranging the impellers in opposite directions, the thrust forces in the axial direction are canceled each other, and the balance of the thrust forces in the axial direction can be easily obtained without providing a balance hole. Therefore, as compared with the conventional independent two-pump system, the effect of improving the pump efficiency is extremely large.

〔Example〕

Next, an embodiment of a canned motor pump for an absorption refrigerator according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view of an essential part showing an embodiment of the canned motor pump of the present invention. In FIG. 1, reference numeral 40 denotes a motor casing of the canned motor portion M, a pump casing 42 constituting the _first pump portion P ₁ is provided at one end of the motor casing 40, and a second pump is provided at the other end. A pump casing 44 that constitutes part P ₂ is provided. Therefore, the first pump portion P ₁ includes the suction pipe portion 50 and the discharge pipe portion 52 that communicate with the inside of the pump chamber 48 in which the impeller 46 is provided, and the impeller 46 has one extension end of the rotor shaft 54 of the motor portion M. It is attached to the section. On the other hand, the motor section M comprises a stator assembly 56 and a rotor assembly 58, and the rotor shaft 54 is supported by a front bearing 60 and a rear bearing 62, respectively. In this case, the front bearing 60 is held by a front bearing housing 66 which is provided to define the pump chamber 48 of the first pump portion P ₁ and the front rotor chamber 64 of the motor portion M, and also the rear portion. The bearing 62 is the second pump part.
It is held by a rear bearing housing 72 which is provided to define a P ₂ pump chamber 68 and a motor unit M rear rotor chamber 70. The second pump portion P ₂ includes a suction pipe portion 74 and a discharge pipe portion 76 that communicate with the pump chamber 68, and has a motor portion M.
An impeller 78 is attached to the other extended end of the rotor shaft 54.

In the canned motor pump having the above structure,
In the bearing housing 66 that defines the pump portion P ₁ and the motor portion M of the above, a through hole 80 is formed in the discharge side portion of the pump chamber 48, and the second pump portion P ₂ and the motor portion M are A through hole 82 is formed in a rear side bearing portion 72 of the rear bearing housing 72 that defines the rear surface side of the impeller 78. Therefore, in this embodiment, the first pump section P ₁ is set to a high head and the _second pump section P ₂ is set to a low head. Reference numeral 84 indicates a terminal box for supplying electric power to the canned motor.

Next, the operation of the canned motor pump of the present embodiment configured as described above will be described. When the canned motor pump of this embodiment is used in an absorption refrigerator, as shown in FIG. 3, the first pump portion P ₁ having a high head is for supplying high-temperature absorption liquid, and its suction pipe portion is used. The 50 is connected to the low temperature regenerator 12 and the discharge pipe 52 is connected to the high temperature regenerator 10 via the high temperature heat exchanger 24. The second pump section P ₂ having a low head is for supplying the low temperature absorption liquid, and the suction pipe section 74 thereof is connected to the absorber 18 and the discharge pipe section 76 is connected to the low temperature heat exchanger 26.
And is connected to the low temperature regenerator 12 through. Since other configurations are the same as those shown in FIG. 4, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

When the canned motor pump of this embodiment is driven in the above-mentioned configuration, a part of the discharged low-temperature absorption liquid from the low-temperature regenerator 12 pumped by the _first pump portion P ₁ is part of the bearing housing. It is introduced into the front rotor chamber 64 through a through hole 80 provided in 66. Front rotor chamber 64
The liquid introduced into the pump chamber 48 is partly lubricated to the front bearing 60 and flows back into the pump chamber 48 through the shaft penetrating portion gap that penetrates the rotor shaft 54 of the front bearing housing 66. In this case, in the canned motor pump of this embodiment, the impeller
The balance hole is not provided in 46, and the liquid is circulated to the back side of the impeller 46 to reduce the amount of internal leakage. Most of the liquid introduced into the front rotor chamber 64 is transferred to the rear rotor chamber 70 via the space between the rotor and the stator.

Liquid introduced into the rear rotor chamber 70 is partially pump from the shaft through portion gaps second through which the rotor shaft 54 of the rear bearing housing 72 and lubricate the rear bearing 62 portion P ₂
Out into the pump chamber 68. Also in this case, the balance hole is not provided in the impeller 78, and the liquid is guided to the back side of the impeller 78. Then, the liquid introduced into the rear rotor chamber 70 passes through the through holes 82 provided in the rear bearing housing 72.
Through the inside of the pump chamber 68. Therefore, in this way, the low temperature regenerator pumped by the _first pump portion P ₁
Part of the absorption liquid supplied from 12 is the canned motor unit M
After passing through the inside, most of it flows out to the _second pump section P ₂ , is returned to the low temperature regenerator 12, and is again sent to the high temperature regenerator 10 by the first pump section P ₁ .

FIG. 2 shows another embodiment of the canned motor pump according to the present invention. That is, in this embodiment, the inducers 86 and 88 are provided at the tips of the impellers 46 and 78 in order to improve the suction performance of the first pump portion P ₁ and the second pump portion P ₂ , respectively. Is characterized by. Other configurations are the same as those of the embodiment shown in FIG. 1, and the same components are designated by the same reference numerals, and detailed description thereof will be omitted. The canned motor pump of the present embodiment configured as described above can also be connected to the pipe as in the above-described embodiment to configure an absorption refrigerator.

In the canned motor pump shown in FIGS. 1 and 2 described above, when the pipe is actually connected as an absorption refrigerator, the suction pipe portion 50 of the first pump portion P ₁ having a high lift is The discharge pipe section 52 and the discharge pipe section 52 can be welded to the pipes respectively communicating with the low temperature regenerator 12 and the high temperature regenerator 10 to reduce the leakage of the absorbing liquid and improve the high vacuum property of the pump. As for the second pump section P _{2 having} a low head, the suction pipe section 74 and the discharge pipe section 76 are respectively provided in the absorber.
The canned motor pump can be maintained by connecting the pipes communicating with the low temperature regenerator 12 and the pipe 18 to each other via a flange so that the pipe can communicate with the canned motor pump.

〔The invention's effect〕

As is apparent from the above-mentioned embodiments, according to the present invention,
A part of the absorption liquid as the pump handling liquid supplied into the canned motor portion flows from the discharge portion of the first pump portion having a high lift to the discharge portion of the second pump portion having a low lift, and this absorption liquid is It is supplied to the low temperature regenerator and again sent to the high temperature regenerator by the first pump unit. Therefore, the internal pressure of the absorbing liquid supplied into the canned motor portion can be kept high, and the occurrence of cavitation can be effectively prevented. In addition, since the pump units are installed at both ends of the canned motor unit to operate at the same time, the axial thrust force generated in each impeller by the pump operation is canceled by the impellers arranged in opposite directions. The axial thrust force is easily balanced. Therefore, stable pump operation can be achieved without providing a balance hole in each impeller, and the amount of internal leakage due to the balance hole can be significantly reduced to improve pump efficiency. Further, according to the present invention, since the two pump units are driven by the common canned motor unit, it is possible to reduce the size of the dual pump structure, and at the same time, the pumps for two pumps when constructing the absorption refrigerator. There are many advantages such as that the installation space can be reduced and the manufacturing cost can be reduced.

According to the canned motor pump of the present invention, on the pump section side of high lift, the suction pipe portion and the discharge pipe portion can be welded to the high-temperature absorbing liquid supply pipe to improve the high vacuum property, In addition, the suction pipe part and the discharge pipe part on the low lift pump side can be connected and separated by a flange so that the whole pump can be maintained easily and at the same time a high vacuum is maintained by welding pipes. it can. Further, according to the canned motor pump of the present invention, by providing an inducer on the suction side of the impeller of each pump portion, it is possible to improve the suction performance of the absorbing liquid and the refrigeration efficiency.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief description of drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of a canned motor pump for an absorption refrigerator according to the present invention, and FIG. 2 is a sectional view of a main part showing another embodiment of the canned motor pump of the present invention.
FIG. 4 is a system diagram of an absorption chiller to which the canned motor pump of the present invention is applied, and FIG. 4 is a system diagram of an absorption chiller using a general pump. 10 …… High temperature regenerator, 12 …… Low temperature regenerator 14 …… Condenser, 16 …… Evaporator 18 …… Absorber, 20,22 …… Pump 24 …… High temperature heat exchanger, 26 …… Low temperature heat exchange Unit 28 …… Piping, 30 …… Circulation pump 40 …… Motor casing 42,44 …… Pump casing 46 …… Impeller, 48 …… Pump chamber 50 …… Suction pipe part, 52 …… Discharge pipe part 54 …… Rotor Shaft, 56 ...... Stator assembly 58 …… Rotor assembly, 60 …… Front bearing 62 …… Rear bearing, 64 …… Front rotor chamber 66 …… Front bearing housing 68 …… Pump chamber, 70 …… Rear rotor Chamber 72 …… Rear bearing housing 74 …… Suction pipe part, 76 …… Discharge pipe part 78 …… Impeller, 80, 82 …… Through hole 84 …… Terminal box, 86, 88 …… Inducer

Claims (4)

[Claims] 1. A pump unit with a high lift and a pump unit with a low lift are configured by disposing impellers on both ends of a canned motor unit with a rotor shaft as a common shaft in opposite directions. A canned motor pump for an absorption refrigerating machine, characterized in that a part of the liquid handled by the pump is introduced into the canned motor portion from the side and the introduced liquid is caused to flow out to the discharge side of the low lift pump portion. 2. A pump having a high head is connected to a pipe for supplying an absorbing liquid from a low temperature regenerator of an absorption refrigerator to a high temperature regenerator, and a pump having a low head is connected to an absorber of an absorption refrigerator. The canned motor pump for an absorption refrigerator according to claim 1, wherein the canned motor pump is connected to a pipe for supplying an absorption liquid to the low temperature regenerator. 3. An absorption refrigerator according to claim 1, wherein an inducer for improving suction performance is attached to the suction side of each impeller in the high lift pump section and the low lift pump section. Canned motor pump. 4. A suction pipe section and a discharge pipe section of a pump section with a high lift are respectively connected by welding, and a suction pipe section and a discharge pipe section of a pump section with a low lift are respectively connected and separated by fasteners via flanges. The canned motor pump for an absorption chiller according to claim 1 or 2, wherein the canned motor pump is freely connected by piping.