JPH0530999B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a shaft sealing device for high-pressure fluid machinery, such as a handling fluid chamber filled with handling fluid in a multi-stage canned motor blower. The present invention relates to a shaft sealing device that always maintains the pressure difference before and after a mechanical seal that seals the shaft within a set range by following the pressure change of the handled fluid.

(Prior Art) Mechanical seals are generally used as shaft sealing means for fluid machines that handle fluids that do not want to leak to the outside and fluid machines that handle high-pressure fluids.

Even if this mechanical seal is used for high pressures of several 100 Kgf/ ^cm2 , the difference in pressure between the front and rear of the mechanical seal, that is, the handling fluid chamber filled with the adjacent handling fluid via the mechanical seal, and the mechanical seal circulating fluid are sealed. The permissible pressure difference with the circulating fluid chamber is at most several 100 Kgf/cm ² , so if the fluid to be handled has a high pressure, it is necessary to pressurize the circulating fluid to a higher level.

In that case, a high-pressure pump such as a gear pump or plunger pump is used as the circulating fluid pump, but it is used when the mechanical seal has a large diameter or is affected by the heat of high-temperature handling fluid, or when driving a canned motor or wet type motor. In a seal-less fluid machine that uses a power source or a magnetic coupling transmission device, when the circulating fluid for lubricating and cooling the drive source or transmission device is also used as the mechanical seal circulating fluid, it is necessary to circulate at a considerable flow rate. liquid is required, which means that a large, high discharge pressure pump is required.

(Problem to be solved by the invention) However, large, high-discharge-pressure gear pumps have extremely poor versatility, are expensive, and have the drawback of high noise, while plunger pumps are even more expensive, and in any case, they cannot be operated. The cost is high.

In addition, as shown in FIG. 7, in a fluid machine 3 in which the rotating shaft 2 is exposed to the outside in order to be connected to the drive source 1, a mechanical seal is used to seal the handling fluid chamber 4 and the circulating fluid chamber 5. In addition to 6, a mechanical seal 7 is required to axially seal the circulating fluid chamber 5 and the outside, and if the differential pressure between the handling fluid chamber 4 and the outside is greater than the maximum allowable differential pressure of the mechanical seals 6 and 7, As shown in the figure, a circulating fluid chamber 8 and a mechanical seal 9 are further provided, and two high-pressure pumps 1 are installed.
0, 11, etc., so that the differential pressure before and after each mechanical seal 6, 7, or 9 must be configured to be below the maximum allowable differential pressure, which has the problem of making the structure complicated and extremely expensive. are doing.

Furthermore, if the pressure of the fluid to be handled is high, the pressure of the fluid to be handled may fluctuate greatly during steady operation of the fluid machine 3, and even if the pressure of the fluid to be handled is approximately constant and does not change during steady operation, When the handling fluid chamber 4 that is shaft-sealed by the mechanical seal 6 is on the discharge side of the fluid machine 3, or when the handling fluid begins to be heated and pressurized by another device at the same time as the fluid machine 3 is started, and then flows into the fluid machine 3. , from startup to steady operation and from steady operation to stop, the handling fluid chamber 4
Since the pressure changes, a device is required to follow this pressure change and change the pressure in the circulating fluid chambers 5 and 8 to maintain the differential pressure across the mechanical seals 6, 7, and 9 within a constant range. .

As shown in FIG. 7, a constant differential pressure regulating valve 12 is used as a device for obtaining this constant differential pressure. 14 circulating fluid to high pressure pump 1
A device has been considered in which the circulating fluid flows from the circulating fluid chamber 5 to the valve inlet 15 of the constant differential pressure regulating valve 12 and returns to the circulating fluid tank 14 from the valve outlet 16 for circulation.

According to this device, the circulating fluid that has flowed into the valve inlet 15 of the constant differential pressure regulating valve 12 from the circulating fluid chamber 5 is transferred to the inlet chamber 17, the lower orifice 20 formed between the lower spool 18 and the intermediate chamber 19, and the intermediate chamber. 19, and an upper orifice 22 formed between the upper spool 21 and the intermediate chamber 19 to flow out from the valve outlet 16, but the intermediate chamber 19 is communicated with the pressure equalizing chamber 24 of the lower spool 18, and the lower spool 18 is Since it is supported by an adjustment screw 26 via a spring 25, for example, when the pressure in the intermediate chamber 19 increases, the lower pressure equalizing chamber 24 and the lower orifice 20, which have the same pressure as the intermediate chamber 19, are caused by the pressure equalizing hole 23. Due to the flow path resistance, the pressure difference between the intermediate chamber 19 and the inlet chamber 17, which has a higher pressure, is reduced, and the balance between this pressure difference and the force of the spring 25 is disrupted, and the lower spool 18 is moved upward, causing the lower orifice 20 to move upward. is narrowed down to the entrance chamber 17
, the pressure difference between the inlet chamber 17 and the lower pressure equalizing chamber 24 is increased, and the lower spool 18 is stopped at a position where it is balanced with the force of the spring 25.
That is, the pressure in the inlet chamber 17 is always maintained at a substantially constant level higher than the pressure in the intermediate chamber 19;
Further, since the upper pressure equalization chamber 27 covering the bellows chamber 13 is communicated with the intermediate chamber 19 via the pressure equalization hole 28, for example, when the pressure in the bellows chamber 13 increases,
The upper spool 21 is moved downward with the expansion of the bellows 29, the upper orifice 22 is narrowed, and the pressure in the intermediate chamber 19 is increased, and the upper pressure equalizes to the same pressure as the intermediate chamber 19 through the pressure equalizing hole 28. The upper spool 21 is stopped at a position where the pressure in the chamber 27 and the pressure in the bellows chamber 13 are balanced, that is, the pressure in the bellows chamber 1
The handling fluid chamber 4 and the intermediate chamber 19 of the fluid machine 3, which have the same pressure as the fluid machine 3, are always maintained at approximately the same pressure,
Therefore, even if the pressure in the handling fluid chamber 4 changes, the pressure in the circulating fluid chamber 5 is always maintained at a substantially constant level higher than this pressure.

However, due to its mechanism, the constant differential pressure regulating valve 12 has
Although the pressure in the circulating fluid chamber 5 can be made to follow pressure changes within a certain range of the handling fluid chamber 4 while maintaining an approximately constant differential pressure, it is not possible to maintain a constant differential pressure over a wide range of pressure changes. , there are also problems with reproducibility,
It has drawbacks such as being prone to failure in a relatively short period of time.

The present invention was made in view of the above-mentioned problems, and it directly connects a canned motor or a wet type motor.
Alternatively, a high-pressure fluid machine with a drive source connected via a magnetic coupling, that is, a high-pressure fluid machine with a completely leak-free structure in which the rotating shaft is not exposed to the outside, is used to completely prevent the fluid being handled from leaking to the outside. ,
In addition, the handling fluid is applied to one shaft sealing part for preventing handling fluid such as gas, slurry-containing liquid, or high-temperature fluid that interferes with lubrication or cooling of the bearing or driving part from entering the bearing or driving part. Even at high pressures, there is no need to install a mechanical seal, its circulating fluid chamber, or multiple high-pressure pumps for pressurizing the circulating fluid chamber, ensuring that the differential pressure across the mechanical seal is always within the set range regardless of pressure changes in the fluid being handled. The present invention provides a shaft sealing device for a high-pressure fluid machine, which can be maintained at a high temperature, greatly improve reliability and service life, reduce equipment costs and operating costs, and reduce noise.

[Structure of the invention]

(Means for Solving the Problems) A shaft sealing device for a high-pressure fluid machine according to the present invention seals a handling fluid chamber filled with handling fluid in a high-pressure fluid machine with a completely leak-free structure in which the rotating shaft is not exposed to the outside. A circulating fluid chamber is provided adjacent to the handled fluid chamber through a mechanical seal, and a closed circulation path is formed in which circulating fluid is supplied and circulated by a circulation pump to this circulating fluid chamber, and a high pressure is applied to pressurize this closed circulation path. A differential pressure detecting means is provided with a pressurizing means such as a pump and a depressurizing means for reducing the pressure in the closed circulation path, and detects a differential pressure between the handling fluid chamber side and the circulating fluid chamber side of the mechanical seal; The pressurizing means and the mechanical seal are configured to make the pressure on the circulating fluid chamber side higher than the handling fluid chamber side of the mechanical seal in response to a signal from the differential pressure detecting means, and to maintain the differential pressure within a set range. The pressure reducing means is provided with a pressure control means for controlling the pressure reducing means.

(Function) In the shaft sealing device for a high-pressure fluid machine of the present invention, circulating fluid is circulated through a closed circulation path by a circulation pump and supplied to a circulating fluid chamber, thereby lubricating and cooling a mechanical seal. The differential pressure between the handled fluid chamber side and the circulating fluid chamber side of the seal is detected by the differential pressure detection means, and the pressure control means that receives a signal from the differential pressure detection means operates the pressurization means and the pressure reduction means. The pressure in the closed circulation path is increased or decreased and controlled so that the pressure on the circulating fluid chamber side of the mechanical seal is higher than on the handled fluid chamber side and the differential pressure is maintained within a set range.

(Example) Next, an example in which the present invention is applied to a multi-stage canned motor blower will be described.

In FIG. 1, reference numeral 31 denotes a high-voltage multi-stage canned motor blower in which a multi-stage blower section 32 and a canned motor section 33 are integrally configured in an airtight manner. The impellers 36 of each stage and the casings 37 of each stage are arranged in a back-to-back combination on both sides of the discharge port 38, and a front mechanical seal 39 for sealing the blower rotating shaft 35 is provided at both ends of the outer casing 34. and a rear mechanical seal 40, respectively, and the outer casing 3 is filled with handling gas.
A front circulating fluid chamber 42 and a rear circulating fluid chamber 43 are formed adjacent to each other through mechanical seals 39 and 40 at both ends of the handling gas chamber 41, respectively. Front blower bearing 44 and rear blower bearing 4 respectively
A blower rotating shaft 35 is rotatably supported by both blower bearings 44 and 45.

In addition, the multi-stage blower section 32 and the canned motor section 3
3, the front canned motor bearing 47 and the rear canned motor bearing 4
A canned motor rotating shaft 49 and a blower rotating shaft 35, which are rotatably supported at 8, are connected by a shaft coupling 50.

Further, the front circulating fluid chamber 42 and the rear circulating fluid chamber 43 are connected through a circulation pipe 51, and the suction port 53 of the circulation pump 52 with a low discharge pressure is connected to the front circulating fluid chamber 42 through the circulation pipe 54. An outlet 55 connects to the canned motor section 33 via a heat exchanger 56 and a circulation pipe 57.
The circulation pump 52 supplies the circulating fluid to the heat exchanger 56, the circulation pipe 57, the rear end chamber 58, the rear canned motor bearing 48, the rear rotor chamber 59, the can gap 60, and the rear end chamber 58.
Front rotor chamber 61, front canned motor bearing 4
7, the inner space of the adapter 46, the rear circulating fluid chamber 43 containing the rear blower bearing 45 and the rear mechanical seal 40, the circulation pipe 51, the front circulating fluid chamber 42 containing the front mechanical seal 39 and the front blower bearing 44; It circulates through the circulation pipe 54, and both mechanical seals 39, 40 and both blower bearings 44, 45
A closed circulation path 64 is formed that lubricates both canned motor bearings 47 and 48 and cools them and the stator 62 and rotor 63 of the canned motor section 33.

Also, a high pressure pump 67 with an extremely low flow rate consisting of a combination of a plunger pump 65 and an accumulator 66 or a gear pump, a circulating fluid tank 68 connected to the suction side of the high pressure pump 67, and a circulating fluid tank 68 connected to the discharge side of the high pressure pump 67. Pressure control valve 6
9 and a safety valve 70, the other end of the pressurization control valve 69 is connected to the circulation pipe 57 that connects the heat exchanger 56 and the rear end chamber 58 of the canned motor section 33. The pressurizing means 71 is connected to a closed circulation path 64,
One end of the pressure reduction control valve 72 is connected to the circulation pipe 57 and the other end is connected to the circulation fluid tank 68, and the pressure reduction means 73
is configured.

In addition, a first
pressure sensor 74 , the handling gas chamber 4 adjacent to the front circulating fluid chamber 42 via the front mechanical seal 39
The suction port 7 of the multi-stage blower section 32 has almost the same pressure as 1.
The second pressure sensor 76 detects the pressure of the first
The pressurizing pressure indicator controller 78 compares the direct signal of the pressure sensor 74 with the indirect signal via the pressurizing bias circuit 77 of the second pressure sensor 76 and the direct signal of the first pressure sensor 74 and the second pressure sensor 76. A differential pressure detecting means 81 is provided, which includes a pressure reducing pressure indicating regulator 80 for comparing and instructing an indirect signal from the pressure sensor 76 via the reducing pressure bias circuit 79. Pressure control valve 69
The pressurizing pressure indicating regulator 78 for controlling the pressurizing pressure indicating regulator 78 and the reducing pressure indicating regulator 80 for generating a control signal to control the pressure reducing control valve 72 of the pressure reducing means 73 constitute the pressure controlling means 82.

The pressure on the front circulating fluid chamber 42 side of the front mechanical seal 39 is higher than that on the handling gas chamber 41 side, and the differential pressure is determined to be within the range of the maximum allowable differential pressure of the front mechanical seal 39. When the differential pressure between the handling gas chamber 41 side and the front circulating fluid chamber 42 side of the front mechanical seal 39 matches the lower limit setting differential pressure with respect to the upper limit setting differential pressure and the lower limit setting differential pressure, the pressurizing pressure is determined. The pressurization bias circuit 77 is adjusted so that the direct signal of the first pressure sensor 74 and the indirect signal of the second pressure sensor 76 to the indicating controller 78 are equal in value, and the handling gas of the front mechanical seal 39 is When the differential pressure between the chamber 41 side and the front circulating fluid chamber 42 side matches the upper limit setting differential pressure, a direct signal from the first pressure sensor 74 and the second pressure sensor 76 are sent to the decompression pressure indicating controller 80. The reduced pressure bias circuit 79 is adjusted so that the value of the indirect signal is equal to that of the indirect signal.

Further, a pressure switch 84 is connected to the discharge side of the high-pressure pump 67 to operate a power supply relay 83 of the high-pressure pump 67.
The operating pressure 4 is determined by the discharge side pressure 67 of the high pressure pump being the sum of the maximum pressure on the handling gas chamber 41 side of the front mechanical seal 39 and the upper limit setting differential pressure, that is, the maximum pressure in the front circulating fluid chamber 42. When the pressure on the discharge side of the high-pressure pump 67 reaches a pressure sufficient to pressurize the closed circulation path 64, the high-pressure pump 67 is stopped, and when the pressure decreases further, the high-pressure pump 67 is started again. Pressure means 71
The system is designed to reduce operating costs.

In addition, if necessary, a temperature sensor 85 for detecting the temperature of the circulating fluid in the front circulating fluid chamber 42, an inverter 86 for driving the circulation pump 52, and a temperature sensor 8
5 and a temperature setting circuit 87 to control the inverter 86.
8 is provided, and the discharge flow rate of the circulation pump 52 is controlled so that the temperature of the circulating fluid in the front circulating fluid chamber 42 becomes a set temperature, that is, the amount of heat released from the circulating fluid in the heat exchanger 56 is controlled. has been done.

Next, the operation of the embodiment configured as above will be explained.

Before starting the multi-stage canned motor blower 31, the circulation pump 52 of the closed circulation path 64 and the pressurizing means 7
1. When the pressure reducing means 73, the differential pressure detecting means 81 and the pressure controlling means 82 are operated, the circulating liquid in the closed circulation path 64 is supplied to the heat exchanger 5 by the circulation pump 52.
6. Circulation pipe 57, rear end chamber 58, rear canned motor bearing 48, rear rotor chamber 59, can gap 60, front rotor chamber 61, front canned motor bearing 47, space inside adapter 46, rear blower bearing 45 and rear mechanical It is circulated to the circulation pump 52 via the rear circulation liquid chamber 43 containing the seal 40, the circulation pipe 51, the front bearing liquid chamber 42 containing the front mechanical seal 39 and the front blower bearing 44, and the circulation pipe 54, and In the pressure reducing means 73, the pressure reducing control valve 72 is closed, and in the pressurizing means 71, the pressure control valve 69 is closed and the pressure on the discharge side thereof is increased by the high pressure pump 67. When the pressure reaches the set pressure of the pressure switch 84, the power supply relay 83 is activated. is shut off, the high pressure pump 67 is stopped, and the pressurizing means 71 is switched to the pressure switch 8.
The pressure is maintained at a set pressure of 4.

Then, the pressure in the front circulating fluid chamber 42 is detected by the first pressure sensor 74, and the pressure at the suction port 75 of the multistage blower section 32 becomes approximately the same pressure as that on the handling gas chamber 41 side of the front mechanical seal 39. Detected by the second pressure sensor 76, the direct signal of the first pressure sensor 74 and the indirect signal of the second pressure sensor 76 via the pressurizing bias circuit 77 are compared by the pressurizing pressure indicating controller 78. The control signal causes the differential pressure between the handling gas chamber 41 side and the front circulating fluid chamber 42 side of the front mechanical seal 39, that is, the differential pressure across the front mechanical seal 39 to reach the lower limit set differential pressure. The pressure control valve 69 is opened until the pressure from the pressure means 71 is applied to the closed circulation path 64.

Next, when the multi-stage canned motor blower 31 is started, the circulating fluid circulated through the closed circulation path 64 causes both mechanical seals 39, 40, both blower bearings 44, 45, both canned motor bearings 47,
48 are lubricated, and the stator 62 and rotor 63 of the canned motor section 33 are cooled and operated smoothly.

When the pressure of the handling gas sucked into the suction port 75 of the multistage blower section 32 increases during operation of the multistage canned motor blower 31, the lower limit of the pressure on the handling gas chamber 41 side of the front mechanical seal 39 increases. If the sum with the set differential pressure tends to be higher than the pressure in the front circulating fluid chamber 42, the pressure control valve 69 is opened by the control signal from the pressure indicating controller 78 for pressurization, and the pressure in the pressure means 71 is increased. Pressure is applied to the closed circulation path 64 so that the pressure in the front circulating fluid chamber 42 does not become lower than the sum of the pressure on the handling gas chamber 41 side of the front mechanical seal 39 and the lower limit set differential pressure. The pressure in the front circulating fluid chamber 42 is increased so that the differential pressure across the seal 39 does not become smaller than the lower limit set differential pressure.

Note that at this time, the pressurizing means 71 is connected to the closed circulation path 6.
4 is pressurized, but the pressure is reduced, so the pressure switch 84 is activated and the high pressure pump 67 is operated, and the differential pressure across the front mechanical seal 39 matches the lower limit set differential pressure, and the pressure control valve 69 is activated. After the high-pressure pump 67 is closed, when the discharge side pressure of the high-pressure pump 67 reaches the set pressure of the pressure switch 84, the high-pressure pump 67 is stopped.

Conversely, when the pressure of the handling gas sucked into the suction port 75 of the multistage blower section 32 decreases during operation of the multistage canned motor blower 31, the pressure on the handling gas chamber 41 side of the front mechanical seal 39 decreases. If the sum of the pressure and the upper limit setting differential pressure tends to be lower than the pressure in the front circulating fluid chamber 42, the pressure reduction control valve 72 is opened by the control signal from the pressure reduction pressure indicator controller 80, and this valve 72 is opened. A closed circulation path 64 is opened to the circulating fluid tank 68 through the sealing fluid tank 68, and the pressure in the front circulating fluid chamber 42 does not exceed the sum of the pressure on the handling gas chamber 41 side of the front mechanical seal 39 and the upper limit setting pressure. That is, the pressure in the front circulating fluid chamber 42 is lowered so that the differential pressure across the front mechanical seal 39 does not become larger than the upper limit set differential pressure.

In this way, the differential pressure before and after the front mechanical seal 39 follows the pressure change regardless of the pressure change in the handling gas chamber 41, and is always between the upper limit set differential pressure and the lower limit set differential pressure, i.e. The pressure in the rear circulating fluid chamber 43 is maintained at a predetermined value within the maximum allowable differential pressure of the front mechanical seal 39, and the pressure in the rear circulating fluid chamber 43 is lower than the pressure in the front circulating fluid chamber 42 by the pressure drop due to the line resistance of the circulation pipe 51. Although the pressure drop is higher (10
The difference between the front and rear mechanical seals 40 is extremely small compared to the upper and lower limit setting differential pressures (tens of kg/ ^{cm 2 to} several tens of kgf/cm ² ) and can be ignored in practical terms. Front mechanical seal 3
9, the differential pressure is always maintained between the upper limit setting differential pressure and the lower limit setting differential pressure, so that the pressure in the handled gas chamber 41 becomes higher than the pressure in both circulating fluid chambers 42 and 43, and the handled gas flows into both circulating fluids. It invades the chambers 42, 43, and not only the mechanical seals 39, 40 but also the bearings 44, 4.
5, 47, 48, and the cooling of the stator 62 and rotor 63, leading to failure, or conversely, the pressure in the handling gas chamber 41 becomes too low and the circulating fluid chambers 42, 43 and Each mechanical seal 3
The mechanical seals 39 and 40 will not be significantly worn or damaged due to an increase in the PV values of the seals 9 and 40, thereby preventing them from failing.

Further, the circulating fluid in the closed circulation path 64 is supplied to both mechanical seals 39 and 40, and both blower bearings 44 and 45.
The temperature rises due to the rotational friction heat of both canned motor bearings 47 and 48, the heat generated by the stator 62 and rotor 63, and the heat of the handled gas, while the heat is radiated through the heat exchanger 56, circulation pipes 51, 54, 57, etc. The temperature is lowered and circulated at a temperature at which the amount of heat received and the amount of heat released are in balance. This temperature is detected by the temperature sensor 85 and compared with the set temperature of the temperature setting circuit 87 by the temperature indicating controller 88. When the circulating fluid temperature is higher than the set temperature, the output frequency of the inverter 86 is increased and the discharge flow rate of the circulation pump 52 is increased, that is, the amount of heat released by the heat exchanger 56 etc. is increased and the circulating fluid temperature is lowered. Conversely, when the circulating fluid temperature is lower than the set temperature, inverter 8
6 is lowered and the discharge flow rate of the circulation pump 52 is reduced, that is, the amount of heat released by the heat exchanger 56 etc. is reduced and the temperature of the circulating fluid is increased. Canned motor section 3
Even if there is a change in the amount of heat received by the circulating fluid due to a change in the calorific value of 3 or a change in the temperature of the handled gas flowing into the suction port 75, or a change in the outside temperature, the circulating fluid will not be released in the heat exchanger 56, etc. Even if there is a change in the amount of heat, the circulating fluid temperature is always maintained at the set temperature.
0, each of the bearings 44, 45, 47, 48, the stator 62, and the rotor 63 will not be insufficiently cooled and cause a failure, and the discharge flow rate of the circulation pump 52 will be reduced when the amount of heat received by the circulating fluid is small. Since the power consumption is reduced, the operating cost of the circulation pump 52 is reduced.

Further, the pressure in the closed circulation path 64 is increased by a pressurizing means 71.
Therefore, the circulation pump 52 includes both mechanical seals 39, 40 and each bearing 44, 45,
47 and 48 and the canned motor section 33 can be obtained, the discharge pressure may be low.
Compared to obtaining the pressure and flow rate required for step 4 with a single pump, the power required is several tenths to several hundredths of that of a very small pump, and the equipment and operating costs are low, and the noise is significantly reduced. It gets lower.

Furthermore, the high-pressure pump 67 of the pressurizing means 71 only needs to have an extremely small flow rate as long as the discharge pressure is sufficient to pressurize the closed circulation path 64, so an ultra-small pump can be used, reducing equipment costs and operating costs. It is inexpensive and produces extremely low noise.

In addition to the above-mentioned embodiment, the differential pressure detection means 81 also detects the differential pressure between the front circulating fluid chamber 42 and the suction port 75 of the multi-stage blower section 32, that is, the pressure difference between the front mechanical seal 39 and the front mechanical seal 39, as shown in FIG. It may be configured only with a differential pressure sensor 89 that directly detects the differential pressure of When adopting the pressure reduction control valve 72, a lower limit differential pressure setting circuit is provided in place of the pressurization bias circuit 77, and an upper limit differential pressure setting circuit is provided in place of the pressure reduction bias circuit 79, although not shown, to adjust the pressure indication for pressurization. The setting signal of the lower limit differential pressure setting circuit and the detection signal of the differential pressure sensor 89 are input to the total 78, and the setting signal of the upper limit differential pressure setting circuit and the detection signal of the differential pressure sensor 89 are input to the pressure reducing pressure indicating controller 80. All you have to do is enter it, but
As shown in FIG. 2, there is a differential pressure setting circuit 90, a pressure indicating regulator 91 that compares and instructs the setting signal of this circuit 90 with the detection signal of the differential pressure sensor 89, and an input signal from this pressure indicating regulator 91. A pressure control means 82 consisting of a comparator 92 for determining and discriminating its output is provided, and the pressure control valve 69 is replaced by a pressure control solenoid valve 93, the pressure reduction control valve 72 is replaced by a pressure reduction solenoid valve 94, and a differential pressure sensor 89 is installed. The pressurizing solenoid valve is set so that the detection signal of the front mechanical seal 39 matches the setting signal of the differential pressure setting circuit 90, that is, the differential pressure before and after the front mechanical seal 39 matches the set differential pressure set by the differential pressure setting circuit 90. The pressure applied to the closed circulation path 64 may be controlled by alternately opening and closing the pressure reducing solenoid valve 93 and the pressure reducing solenoid valve 94.

Although not shown, an orifice is used in the pressure reducing means 73 in place of the pressure reducing control valve 72 and the pressure reducing solenoid valve 94, and the pressure controlling valve 72 is always open and the high pressure pump 67
The discharge flow is circulated through the pressurization control valve 69, the orifice, the circulating fluid tank 68, and the high-pressure pump 67, and by controlling the opening degree of the pressurization control valve 72, a Some circulating fluid pressure,
That is, the pressure in the closed circulation path 64 may be adjusted, and the pressurizing means 71 may also be replaced with the plunger pump 65 or gear pump, for example, by pressurizing the circulating fluid in the closed circulation fluid tank with compressed air and injecting it into the closed circulation path 64. It may also be something you send.

If the handled gas is not corrosive, as shown in FIG. Shaft coupling 50
Only one mechanical seal 97 needs to be installed between the two mechanical seals 97, and one mechanical seal 97 may be installed between the blower rotation shaft and the canned motor rotation shaft, as shown in FIG. It is sufficient to provide only the mechanical seal 97.

In addition to the canned motor, the driving section for configuring the multistage blower with a completely leak-free structure may be a wet type motor that can be replaced with the canned motor, or the multistage blower section 32 may be connected to a magnet as shown in FIG. It is also possible to connect to the general-purpose motor 100 via the coupling 99 to configure a multi-stage blower with a completely leak-free structure.

The embodiments in which the present invention is applied to a high-pressure multi-stage blower have been described above, but it can of course also be applied to a single-stage blower or a roots-type or screw-type compressor.
Although not shown, there is a canned motor pump that uses a mechanical seal to isolate the pump handling liquid containing slurry and high temperature pump handling liquid from the canned motor circulating fluid and prevent the pump handling liquid from entering the canned motor section. As shown in the figure, in a canned motor stirrer 103 that stirs a high-pressure liquid 102 in a hermetic stirring tank 101, it can also be adopted when a shaft seal is formed between the high-pressure gas phase part 104 of the hermetic stirring tank 101 and the canned motor part 105. It can be used in shaft sealing devices for high-pressure fluid machinery where pressure changes are large.

〔Effect of the invention〕

According to the present invention, the high-pressure fluid machine has a completely leak-free structure in which the rotating shaft is not exposed to the outside, which not only completely prevents the handling fluid from leaking to the outside, but also lubricates the bearing or drive part. Even if the fluid to be handled is at high pressure, there is no mechanical seal or its There is no need to install multiple high-pressure pumps to pressurize the circulating fluid chamber and the circulating fluid chamber.
In addition, a closed circulation path is provided in which a circulating pump with a low discharge pressure supplies and circulates the circulating fluid to the circulating fluid chamber of the mechanical seal, and a pressurizing means consisting of a high pressure pump with a low flow rate that pressurizes this closed circulation path and a closed circulation path. The pressure reduction means for reducing the pressure of the fluid being handled is provided, and the pressure difference across the mechanical seal is detected by the differential pressure detection means, and the pressure control means is used to control the pressurization means and the pressure reduction means. The differential pressure before and after the mechanical seal can always be reliably maintained within the set range regardless of changes, greatly improving reliability and service life. Pressure and flow rate are 1
Compared to the case obtained with a single pump, it is extremely small, so the equipment cost and operating cost are low, and the noise is also significantly lower.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a multi-stage canned motor blower showing one embodiment of the shaft sealing device for high-pressure fluid machinery of the present invention, and FIGS. 2 to 4 are multi-stage canned motor blowers showing other different embodiments. A cross-sectional view of
FIG. 5 is a sectional view of a multi-stage blower showing another embodiment;
FIG. 6 is a sectional view of a canned motor stirring device showing another embodiment, and FIGS. 7 and 8 are sectional views of conventional shaft sealing devices. 35... Rotating shaft, 42, 43... Circulating fluid chamber, 6
4... Sealed circulation path, 67... High pressure pump, 71
...pressure means, 73 ... pressure reduction means, 81 ... differential pressure detection means, 82 ... pressure control means.

Claims (1)

[Claims] 1. In a high-pressure fluid machine with a completely leak-free structure in which the rotating shaft is not exposed to the outside, a circulating fluid chamber is provided adjacent to the handling fluid chamber through a mechanical seal that seals the handling fluid chamber filled with the handling fluid, and this Forming a closed circulation path for supplying and circulating circulating fluid by a circulation pump to the circulating fluid chamber, and providing a pressurizing means such as a high-pressure pump for pressurizing this closed circulation path and a depressurizing means for reducing the pressure in the closed circulation path,
differential pressure detection means for detecting a differential pressure between the handling fluid chamber side and the circulating fluid chamber side of the mechanical seal;
The pressure applying means is configured to make the pressure on the circulating fluid chamber side of the mechanical seal higher than the handling fluid chamber side and maintain the differential pressure within a set range based on the signal from the differential pressure detection means. A shaft sealing device for a high-pressure fluid machine, comprising: a pressure control means for controlling the pressure reducing means;