JPH0245687A - Power reducing device for water injection compressor - Google Patents

Abstract

PURPOSE:To contrive the reduction of driving power by increasing a temperature to be held to a fixed degree so as to prevent the temperature from decreasing of injection water into a compressor main unit when it is in no-load operation. CONSTITUTION:After a transfer to no-load operation in a compressor 1, when a temperature of circulating water decreases to a predetermined degree, a water temperature detecting switch TH operates, and receiving its signal, a fan motor 15 for a heat exchanger 11 is stopped. Simultaneously in a compressor main unit 1, a negative pressure is generated in a suction port 13 by closing a suction air passage with an unloader 16, increasing a pressure difference from a delivery port 17 and a leakage amount of compressed air between each acting space 5, and by heat generation by recompression of the leakage air and by heat receiving or the like from each sliding part, water holds its temperature in the vicinity of a degree in the time of full-load operation, being injected into the compressor main unit and repeating circulation.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a water injection system that injects water into the working space of a compressor body to cool and seal the working space. This invention relates to a compressor power reduction device.

(Prior Art) Conventionally, a screw type compressor shown in Japanese Utility Model Application Publication No. 102794/1983 has been known as a type of compressor that cools and seals the working space by injecting or injecting water into the working space of the compressor body. be.

As shown in FIG. 6, this compressor houses a pair of male and female screw rotors 3 in a cylinder casing 2, and rotates the rotors while maintaining a meshing gap with a synchronous gear 4 to perform a compression action and , water pumped from a water circulation system (not shown in Fig. 7) is injected into the working space 5 to cool and seal the working space, and its basic structure is different from that of a conventional oil-cooled compressor.゛It's the same.

As shown in FIG. 7, the water circulation system separates the compressed air in a gas-liquid mixed state discharged from the compressor body 1 into air and water by a separator tough built in the receiver tank 6, and the air is passed through the air supply pipe 8. At the same time, the water is temporarily stored in the lower water tank 9, and from there is passed through the water supply pipe lO heat exchanger 11. The water is fed under pressure through a water supply pipe 12 into the working space 5 of the compressor body or into the input port 13.

Note that 14 is a cooling fan for the heat exchanger 11, and 15 is a fan motor.

In this way, compared to the oil-cooled compressor, the water injection compressor uses water instead of oil as the cooling and sealing medium in the working space 5, and therefore contains no oil in the discharged air, making it suitable for many applications such as food hygiene and pharmaceuticals. It is used in many areas.

(Problem to be Solved by the Invention) A water injection compressor improves volumetric efficiency because the lower the temperature of the water injected into the compressor body, the lower the temperature rise in the suction action space. It is designed to keep it low for a long time.

However, if the injection water temperature is set to be kept low during full load operation as described above, during so-called no-load operation when the intake air passage is blocked by the unloader 16, the injection water temperature will be significantly lower than during full load operation. , the driving power of the compressor does not decrease much compared to when operating at full load.

In other words, the inventors have discovered that during no-load operation, driving power can be reduced by increasing and maintaining the temperature of the water injected into the compressor body to a predetermined temperature.

This is because during no-load operation, the water vapor partial pressure in the suction side working space within the compressor body increases due to the temperature rise of the injected water, and as a result, the negative pressure in the suction side working space is alleviated by the increased amount. As the pressure difference with the discharge port side is reduced and the amount of compressed air leaking from between the working spaces is reduced, the recompression power is reduced and the water vapor partial pressure is increased, causing the water vapor in the working spaces to decrease. This is due to factors such as an increase in the ratio of

Water injection compressors have the above problems, but as explained earlier, during no-load operation, the compression action within the compressor body stops and the amount of heat generated decreases, but the fan motor It is operated continuously and performs the cooling effect of circulating water.

Therefore, in view of the above problems, an object of the present invention is to reduce the driving power of a water injection compressor by increasing and maintaining the temperature at a constant temperature so that the temperature of the water injected into the compressor body does not drop during no-load operation of the water injection compressor. shall be.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above objects, the present invention provides: (1) Water injection that cools and seals the working space by injecting water after passing through the heat exchanger into the working space of the compressor. In the compressor, a water temperature detection switch is provided in the water circulation system, and 9. A control means is provided for maintaining or increasing the temperature of water circulating in the working space of the compressor at a temperature close to the water temperature during full load operation based on a signal from the water temperature detection switch during load operation. As a specific means for this purpose, stopping the passage of the external cooling medium through the heat exchanger or restricting the amount of water injected into the working space of the compressor using a throttle valve;
Alternatively, it is characterized in that the water supply pipe line after passing through the heat exchanger is made to communicate with a bypass pipe via a bypass valve.

(Function) According to the above configuration, after the compressor shifts to no-load operation, when the water temperature drops to a predetermined temperature of the WI ring water, the water temperature detection switch TH is activated, and in response to the signal, the fan motor 15 for the heat exchanger 11 is activated. stops.

At the same time, the unloader 16 in the compressor body 1
Due to the blockage of the intake air passage, the inside of the suction port 13 becomes negative pressure, the pressure difference with the discharge port 17 increases, the amount of compressed air leaking between each working space increases, and the recompression causes heat generation and each sliding part. The temperature of the water injected into the compressor body is maintained at a temperature near the water temperature during full load operation, and the circulation is repeated.

At this time, in the suction side working space, the water vapor partial pressure increases due to the water temperature being raised or maintained, so the negative pressure is offset and relaxed by the increased amount, and the pressure between each working space and the discharge port 17 side increases. reduce the pressure difference. Therefore, the amount of compressed air leaking between each working space is reduced, and the ratio of water vapor in the working spaces is increased, so that the recompression power is reduced and the driving power during the no-load operation is reduced.

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described based on FIGS. 1 and 2.

Note that the same parts as those described in the conventional example will be described using the same reference numerals, and detailed description thereof will be omitted.

1 is a compressor main body, and an unloader 16 is mounted above the suction port 13, and a pressure switch vS for detecting negative pressure is provided in communication with the suction port.

On the other hand, a pressure switch PS-1 is provided in the middle of the air supply pipe 8, and a pressure switch PS-1 is also provided on the side of the receiver tank 6.
-2 is connected, and a water temperature detection switch TH is provided in the water tank 9 below it.

Further, the air outlet 21 of the receiver tank 6 is connected to a solenoid valve S for purging the internal pressure of the tank and a purge valve 22, while a fan motor 15 is disposed in front of the heat exchanger 11, and during no-load operation, the water temperature is It is turned on and off by a signal from the detection switch TH.

As shown in FIG. 2, the control circuits for each of these electrical devices include fan motor 15. The main motors 23 for driving the compressors are connected in parallel, and one of the power supplies is connected to the pressure gas inches PS-1, VS, P
S-2, each connected in series and connected to the other power source via the operating relay 55 of the purge solenoid valve Sv.

Furthermore, a relay 60 for starting and stopping the fan motor 15 is connected in parallel with the relay 55 between the pressure switches VS and PS-2, and its normally closed contact 6Qb is connected to the fan motor electromagnetic contactor 50F. A water temperature detection switch TH is connected in parallel to the closed contact 60b, and the normally closed contact 55b of the relay 55 is connected to the purge solenoid valve SV.

Here, the pressure switch PS-1 turns OFF when the internal pressure of the air supply pipe 8 is above a certain pressure (6.3 kgf/cd) and below it, and the pressure switch VS turns OFF when the suction passage of the unloader 16 is closed. It is turned ON by the negative pressure in the suction port 13, and turned OFF when the passage is open.

Furthermore, the pressure switch PS-2 is turned ON when the internal pressure of the receiver tank 6 is below a certain pressure (1, 2 kg f/cd), and is turned on when the pressure is slightly higher than that (1, 5 kg f/cd).
c+J), and the water temperature detection switch TH is set to be turned OFF when the water temperature is above a predetermined water temperature, and turned OFF when the water temperature is lower than that.

In addition, 40 is a relay for starting the fan motor 15 and the main motor 23, 40a is its normally open contact, 52 is an electromagnetic contactor for the main motor, PB-3 is a stop switch, and PB-R is a start switch.

Next, the operation will be explained.

When the start switch PB-R is turned on, the normally open contact 40a of the relay 40 is closed, the fan motor 15 and the main motor 23 are operated, and the internal pressure of the receiver is gradually increased and compressed to the consumption side after the pressure switch PS-2 is turned on. Start supplying air. Then, when the consumption of compressed air on the consumption side stops, the pressure switch ps-i is turned on, and the rear unloader 16 operates to close the intake air passage.

As a result, the inside of the suction port 13 rapidly becomes negative pressure, and the pressure switch S is turned on, opening the normally open contact 55b of the relay 55 and cutting off the power to the solenoid valve S, which opens the purge valve 23 and pressure inside the receiver tank. is released to a predetermined pressure and maintained at that state.

At the same time, the relay 60 is also energized and its normally closed contact 60b is opened, so that the fan motor 15 is in a stopped state.

At this time, if the circulating water temperature is below a predetermined temperature, the contact of the water temperature detection switch TH is open, and the fan motor 15 continues to operate blindly in a stopped state.

On the other hand, in the compressor main body, the circulating water temperature is circulated and operated at a higher temperature than in the conventional example due to the stop of the fan motor, so that an appropriate water vapor partial pressure is maintained in the working space on the side of the suction port 13, and the working space is maintained. In each working space including the space, the injected water, compressed air, water vapor, etc. are compressed into a gas-liquid mixed state and discharged to the discharge port 17 side.

At this time, the driving power of the compressor is reduced to the value shown by line A in FIG.

If the compressor continues to operate in this state,
The wi ring water temperature gradually rises due to heat generation due to recompression of the compressed air within the compressor body 1 and heat received from each sliding portion. When the predetermined temperature is reached, the contact point of the water temperature detection switch TH closes to operate the fan motor 15 to start cooling the water, and this operation is repeated thereafter.

The present invention is configured and operates as described above, but if the fan motor 15 were to continue to operate even during no-load operation as in the conventional device, the driving power would be equal to the line B in Fig. 3. It will greatly exceed line A as shown in FIG.

According to experiments, the difference in driving power due to the difference in V and circulating water temperature during no-load operation varies slightly depending on the model of the compressor/nosa main body, but it is approximately 4°C for a temperature difference of 10°C in circulating water temperature.
~7%, which is approximately linear over a certain temperature range as shown in FIG.

Although the heat exchanger 13 has been described as an air-cooled type, it may also be a water-cooled type. In that case, the means for supplying water as an external cooling medium is the fan 14. The fan motor 15 may be replaced with a pump and the pump motor. Also, although not shown, a pneumatic or electromagnetic throttle valve may be installed in the middle of the water supply pipe IO or 12 to limit the amount of water injected into the working space during no-load operation. Effects can be obtained.

(Second Embodiment) Fig. 5 shows a second embodiment of the present invention.Instead of the configuration in which the cooling fan is turned off during no-load operation as described in the first embodiment, A bypass valve is installed in the middle of the piping, and when the cooling water temperature is below a predetermined temperature, it is configured to circulate without passing through the heat exchanger.
In this case, the cooling fan is not turned on and off.

Hereinafter, only the parts different from the first embodiment will be explained.

That is, the second embodiment has the relay 60 in FIG. 2, its normally closed contact 60b, and water temperature detection switch T described in the first embodiment.
Delete H.

Then, as shown in 2, the water supply pipe 1 before passing through the heat exchanger 11
A bypass valve 30 with a built-in thermosensitive pellet (not shown) that opens and closes the valve depending on the water temperature is disposed midway through the water supply pipe 10 and the bypass pipe 31 when the circulating water temperature is below a predetermined temperature. , the water is directly introduced into the compressor main body without passing through the heat exchanger 11, and when the water temperature is higher than a predetermined temperature, the bypass pipe is closed and the water supply pipe lO and the heat exchanger 11 are communicated to perform a predetermined heat exchange action. After going,
It is configured to inject water into the compressor main body via the water supply pipe 12.

That is, regardless of the operating state of the compressor main body, the bypass pipe is simply opened or closed depending on the water temperature, thereby constantly maintaining the temperature of the water injected into the compressor main body 1 within a constant range.

As described above, the driving power during no-load operation is reduced by the same effect as explained in the first embodiment.

(Effects of the Invention) As explained above, the present invention maintains the temperature of the water circulating in the compressor body during no-load operation of a water injection compressor at a temperature close to the water temperature during full-load operation, and repeats the circulation. As a result, the driving power does not increase due to excessive cooling of the circulating cooling water during no-load operation as in the conventional case, and the driving power can be stably reduced, resulting in a large energy-saving effect.

In particular, in the first embodiment, since the effect of reducing power consumption due to the stoppage of the fan motor during no-load operation is also added, the power consumption rate as a whole is lower and more economical.

Further, the present invention is applicable not only to screw compressors but also to other types of water injection combustors such as Hoehn compressors.

[Brief explanation of the drawing]

Fig. 1 is a detailed diagram of the first embodiment of the present invention, Fig. 2 is a detailed diagram of its electric control circuit, Fig. 3 is an explanatory diagram showing the power reduction effect during no-load operation, and Fig. 4 is a diagram showing the circulating water temperature. FIG. 5 is a detailed view of the second embodiment; FIG. 6 is a sectional view of a conventional water injection compressor main body; and FIG. 7 is a piping system diagram thereof. 1. Compressor body 3. , , Screw rotor 5 , , Action space 6. , , Receiver tank 10 , , Water supply pipe 11. ,,
, heat exchanger 12, , water supply pipe 1'5. ,
,,fan motor 30,,,bypass valve 31
．． ,,, Bypass pipe funeral diagram (KWI diagram)

Claims (4)

[Claims] (1) In a water injection compressor that cools and seals the working space by injecting water that has passed through a heat exchanger into the working space of the compressor, a water temperature detection switch is provided in the water circulation system, and a water temperature detection switch is provided in the water circulation system. A water injection compressor, characterized in that, during load operation, a control means is provided for maintaining or increasing the temperature of the water circulating in the working space of the compressor near the water temperature during full load operation in response to a signal from the water temperature detection switch. Power reduction device. (2) Power reduction of the water injection compressor according to claim 1, characterized in that the water temperature during the no-load operation is controlled by stopping an external cooling medium passing through a heat exchanger disposed in the water circulation system. Device. (3) The power of the water injection compressor according to claim 1, wherein the water temperature during the no-load operation is controlled by limiting the amount of circulating water using a throttle valve provided in the middle of a water supply pipe in the water circulation system. mitigation device. (4) In a water injection compressor that cools and seals the working space by injecting water that has passed through a heat exchanger into the working space of the compressor, a bypass valve is installed in the water supply pipe line before passing through the heat exchanger. A water injection compressor, characterized in that the water supply pipes before and after passing through the heat exchanger are connected by a bypass pipe via the bypass valve when the water temperature in the pipe is below a predetermined temperature. Power reduction device.