JPS58204989A - Method for operating capacity regulating device upon unloading - Google Patents

Abstract

PURPOSE:To enable a uniform instrumentation gas to be always obtained by utilizing compressed gas in a screw compressor as the instrumentation gas for a capacity regulating valve upon unloading operation. CONSTITUTION:There are presented in the compressing chamber of a compressor 1, internal compressed gas having a pressure increased upto a predetermined pressure due to a designed compression ratio, which is taken out through an instrumentation gas take-up pipe line 9. Discharge pressure comes to rise once a bypass valve 7 becomes in the condition of closing, and therefore, after the discharge pressure has risen, self-supplied compressed air from a main line is used as the instrumentation air, as in the conventional way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a capacity adjustment valve in a scree gas compressor equipped with a capacity adjustment device during no-load conditions.

The capacity adjustment methods for the scree gas compressor include the rotation speed control method, suction valve throttling method, suction valve ON-0FF method,
A bypass method is generally adopted, but in the above three methods except for the rotation speed control method, the suction valve, which is a capacity adjustment valve, and the bypass valve generally use compressed gas as a working medium. Instrumentation gas for the volume control valve is required.

In particular, in cases where a part of the own discharge gas is used as instrumentation gas, there is no instrumentation gas when the compressor starts, so the capacity adjustment valve does not operate and the operation from no-load occurs. Since automatic pressure increase is not possible, instrumentation gas is usually supplied from outside the system only at startup, or a manual handle is provided on the capacity adjustment valve and the handle is manually operated.

The present invention does not require the above-mentioned measures or operations, and by utilizing the internal compressed gas existing inside the scree compressor, the present invention has an extremely simple configuration and maintains constant measurement even during no-load operation or when the discharge pressure fluctuates. The purpose is to provide a method for obtaining charged gas, and its feature is the method of operating the capacity adjustment valve of a scree gas compressor equipped with a capacity adjustment device during no-load conditions. The present invention is characterized in that the internal compressed gas of the screen compressor is used as the charging gas for the capacity adjustment valve during operation.

The present invention will be explained in detail below based on illustrated embodiments.

Figure 1 shows an embodiment in which the present invention is applied to the bypass system.
1) is the scree gas compressor, C2) is the cooler, (3) is the safety valve, and (4) is the check valve t(5)? 'i On-off valves, these form the main line.

(6) is a bypass pipe line from the compressor discharge side to the suction side, and a bypass valve (7) is interposed in the middle. The bypass 9
F (7) is normally open but is actuated via a solenoid valve (8) by a signal from a pressure regulator (PIC).

(mi)) is an instrumented gas extraction conduit that guides the internal compressed gas extracted from the compression chamber of the compressor (1) to the buffer tank 00. The buffer tank 00 is provided for the purpose of avoiding the influence of pulsation of the compressor in order to obtain instrument gas of equal pressure.

Reference numeral 01) is a dryer, which is installed next to dry the instrumentation gas, since moisture contained in the instrumentation gas will have an adverse effect on the instruments. The instrumentation gas led to this dryer 01) operates the pressure regulator (PIC) (1:↓), and the signal from there operates the bypass valve (7) via the solenoid valve (8). It is configured.

Next, to explain the operating principle of the device with the above configuration, the bypass valve (7) is normally open in order to reduce the starting torque of the compressor (1), and the bypass valve (7) is normally open. The solenoid valve (s) f:
Discharge pressure cannot be obtained unless the bypass valve (7) is closed via the bypass valve (7). Therefore, even in no-load operation, the compressor (
In the compression chamber 1), there is internal compressed gas that has been pressurized to a predetermined pressure to achieve the designed internal compression ratio, and this is taken out from the instrumentation gas take-off pipe (9) and transferred to the buffer tank and dryer 01J1. In turn, the compressed gas transmits a signal from the pressure regulator (PIC) through the electromagnetic valve (8) and closes the bypass valve (7). Once the bypass valve (7) enters the closed state, the discharge pressure will rise, so after the discharge pressure rises, the compressed air from the main line will be used as instrument air as before. Ru.

Here, the reason why the internal compressed gas can be taken out in the Sufu IJ aa compressor will be explained based on the P-Va diagram in FIG. 2.

Since the scree compressor is a volumetric expansion compressor, the discharge pressure P'
2. P2 is determined by the pressure in the discharge line, and the internal compression pressure P2, which is determined by the size of the compressor's discharge boat, is usually selected to be equal to the discharge pressure at the design point, so that the power is minimized at the design discharge pressure. Designed. Therefore, in the scree compressor, P2 exists due to internal compression, and as is clear from the figure, even if the discharge pressure fluctuates, this P2 is always constant. Therefore, if the gas at the pressure P2 is taken out, it can be used as a pressure source.

Of course, the P2 pressure value must be selected to be higher than the pressure that activates the instrumentation equipment.

The design condition is to keep the discharge pressure Pt as low as possible when there is no load at startup, and it is generally around 14, so it cannot be used as a pressure source for instrumentation equipment. can be,
On the other hand, the pressure P2 is generally 1.4 K or more, which is sufficient to be used as an operating pressure source.

As detailed above, according to the present invention, by extracting and temporarily using the internal compressed gas compressed inside the scree compressor, even when there is no discharge pressure during no-load operation, the internal compressed gas can be extracted from the outside of the system. Capacity regulating valves can be operated without requiring instrumentation gas or manual operation.

Furthermore, it is an effective means when the discharge pressure fluctuates widely, especially when the lower limit of the discharge pressure is less than the pressure necessary to operate the capacity adjustment valve.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, and FIG. 2 is an explanatory diagram of the principle of internal compression. 1 Niscree compressor 2: Cooler 3: Safety valve 6: Bypass pipe 7: Bypass valve 8: Solenoid valve 9: Instrumentation gas take-off pipe 1O: Batsuwa tank special fraud applicant Kobe Steel, Ltd.

Claims (1)

[Claims] 1) A method of operating a capacity adjustment valve of a friend scree gas compressor equipped with a capacity adjustment device f during no-load operation, wherein the internal compressed gas of the compressor is used as the instrumentation gas of the capacity adjustment valve during no-load operation. A method of operating a capacity adjusting device during no load, characterized in that the device is fully used.