JPS6260902A - Slide valve type screw expander with side stream - Google Patents

Abstract

PURPOSE:To improve the efficiency of power recovery by an expander, by carrying out the fine adjustment of internal expansion ratio with a slide valve for the minute fluctuation of an inlet gas pressure from a steady state. CONSTITUTION:In the steady state operation of high expansion ratio, a variable fixed valve 32 is fixed to the open condition of the pressure equalizing portion 28 of an outlet side so as to equalize internal expansion ration to real expansion ratio, so that gas may be discharged from an outlet 24 after being taken in from an inlet 23 and expanded inside a rotor chamber 21. Then, the closing of the pressure equalizing portion 28 of the gas outlet side is adjusted finely with a slide valve 29 so as to equalize generally the internal expansion ratio to the real expansion ratio for the minute fluctuation of an inlet gas pressure. When the load of a driven equipment being driven by an expander increases, the variable fixed valve 32 is moved to a gas inlet side by a driving portion 33 via a drive shaft 34 to completely, close the pressure equalizing portion 28 of the outlet side and the slide valve 29 is moved to the inlet side to open the pressure equalizing portion 25 of an expansion process. Thus, energy efficiency can be improved.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is capable of easily and efficiently adjusting the output of an expander in response to load fluctuations (including overload) of a driven machine driven by the expander. This invention relates to a slide valve type screw expander with a side stream that can be used as a side stream.

[Prior art]

Conventionally, screw compressors equipped with a slide valve for capacity adjustment have been proposed. As shown in FIG. 3, this compressor with a slide valve has a pair of male and female rotors 2 rotatably supported within a casing 1 of the compressor. Inside the compressor, the rotor 2 is connected from the gas suction port 3.
A gas path is formed that reaches the gas discharge port 4 through a compression chamber (not shown) formed by tooth grooves. A pressure equalizing part 5 with the gas suction port 3 is formed on the gas suction port side of the rotor 2, and a bypass path from the suction process part in the casing 1 to the gas suction port 3 via the pressure equalizing part 5 is formed. It is formed. The pressure equalizing section 5 is configured to be openable and closable by a slide valve 7 driven by a slide valve drive shaft 6.

And Yong! At the time of adjustment, as shown in FIG. 4, the slide valve 7 is moved from the suction side to the discharge side, and a portion of the suction gas is returned to the suction side through the bypass path, thereby reducing the amount of gas to be compressed. By adjusting the amount of gas to be compressed by the slide valve 7, unnecessary compression is not performed, and as shown in FIG. 5, the power required for the compressor is effectively reduced in proportion to the reduced gas volume. This makes it possible to save operating costs and to minimize the load at startup.

On the other hand, when using the above-mentioned screw compressor with a slide valve as an expander, the slide valve alone can only change the internal expansion ratio. unable to respond adequately. Therefore, as shown in FIG. 6, in the conventional screw expander 41, the inlet side gas is controlled by the control valve 43 provided in the gas inlet line 42 in response to load fluctuations including overload of the driven machine (not shown). By changing the conditions,
Correspondence is being taken. However, this control valve 4
3) has the problem that it is not always easy, reliable, or effective.

[Purpose of the invention]

The present invention has been made in consideration of the above problems, and in addition to adjusting the amount of gas to be expanded using a slide valve mechanism in a conventional compressor, the present invention has been developed to adjust the amount of gas to be expanded using a slide valve mechanism in a conventional compressor. By adopting a configuration that allows gas that still has sufficient energy to flow into the expansion process section from the external gas supply path, when dealing with an overload of the driven machine,
It is an object of the present invention to provide a slide valve type screw expander with a side stream that improves the efficiency of power recovery by the expander and can effectively and easily respond to load fluctuations of a driven machine.

[Structure of the invention]

The slide valve type screw expander with side stream of the present invention is provided with a gas outlet side pressure equalizing part communicating with the gas outlet on the gas outlet side in the casing, and a gas path for external gas supply in the gas expansion process part. An expansion process pressure equalizing section connected to the gas outlet side pressure equalizing section is provided, and two positions can be set: a predetermined open/close position of the gas outlet side pressure equalizing section during steady operation, and a fully closed position of the gas outlet side pressure equalizing section during overload. Variable fixed valve mechanism and opening/closing adjustment of the gas outlet side pressure equalizing part during steady operation.
and a slide valve mechanism capable of opening and closing the expansion process pressure equalizing part during overload, and is driven by the expander by gas flowing into the gas expansion process part during overload of the slide valve type. The present invention is characterized in that it is configured so that it can easily and effectively cope with load fluctuations.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 and 2.

A rotor chamber 21 that rotatably supports a pair of male and female rotors 22 is formed in the casing 20 of the screw expander. A gas outlet 24 communicating with the other end of the chamber 21 is formed. An expansion process pressure equalizing part 25 is formed in the gas expansion process part of the rotor chamber 21, and this pressure equalizing part 2
5 is connected to an external gas supply path 27 via a return valve during expansion or an overload valve 26. Adjacent to the gas outlet 24 side of the pressure equalizing section 25, the gas outlet side pressure equalizing section 2
8 is formed, and this pressure equalizing section 28 is connected to the gas outlet 24. A slide valve 29 is provided in the pressure equalizing section 25 and the pressure equalizing section 28 . The slide valve 29 is configured such that the pressure equalizing section 25 and the pressure equalizing section 28 can be opened and closed by a slide valve drive section 30 via a slide valve drive shaft 31 . Furthermore, the above slide valve 2
A variable fixed valve 32 is provided adjacent to 9, and this variable fixed valve 32 can freely adjust the opening and closing of the gas outlet side pressure equalizing section 28 by a variable fixed valve drive section 33 via a variable fixed valve drive shaft 34. It is configured to be.

In the above configuration, during steady operation with a large expansion ratio,
As shown in FIG. 1, the variable fixed valve 32 is fixed at a position where the gas outlet side pressure equalizing section 28 is opened so that the internal expansion ratio of the screw expander becomes the same as the actual expansion ratio. The gas passes through the gas port 23 and expands inside the rotor chamber 21, and then is discharged from the gas outlet 24. In response to slight fluctuations in the inlet gas pressure, the slide valve 29 finely adjusts the opening and closing of the gas outlet side pressure equalizing section 28 so that the internal expansion ratio and the actual expansion ratio are approximately the same. At this time, the external gas supply path 27 is closed by the valve 26.

When the load on the driven machine driven by the expander increases, as shown in FIG. 2, the variable fixed valve 32 is moved to the gas inlet side by the drive section 33 via the drive shaft The outlet side pressure equalizing section 28 is completely closed. Further, the slide valve 29 moves to the gas inlet side, and the expansion process pressure equalizing section 2
5 is in an open state, and gas having a pressure above the equivalent pressure plate of the expansion process section flows into the expansion process section in the rotor chamber 21 through the external gas supply path 27. by this,
The output of the expander can be increased to sufficiently cope with the overload of the driven machine.

〔Effect of the invention〕

The slide valve type screw expander with side stream of the present invention has a variable fixed valve during steady operation with a large expansion ratio.
A force is applied so that the internal expansion ratio of the screw expander becomes the same as the actual expansion ratio mentioned above, and the pressure equalizing part on the outlet side is fixed at a position where the pressure equalizing part is opened. In response to fluctuations, the structure is such that the internal expansion ratio can be finely adjusted using a slide valve.This makes it possible to easily respond to load fluctuations in the driven machine, and to always keep the internal expansion ratio and actual expansion ratio constant. Since it is possible to operate with the ratio substantially the same, energy efficiency can be improved.Furthermore, in the case of an overload of the driven machine, the variable fixed valve is connected to the gas outlet side pressure equalizing part in the present invention. is moved to the closed state and fixed, and by opening the expansion process pressure equalizing section by the slide valve, intermediate pressure gas can flow in from the outside and output can be increased. Since the gas containing energy can be used effectively, the efficiency of power recovery by the expander can be increased, and the overload of the driven machine can be reduced compared to the control valve used in the conventional example. This has the effect of making it easier to handle the load.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a schematic configuration during steady operation in an embodiment of the present invention, Fig. 2 is an explanatory diagram of a schematic configuration when a side stream is used, and Fig. 3 is an explanatory diagram of a schematic configuration of a conventional slide valve type screw compressor. Figure 4 (a) (b) (
c) is P-V corresponding to the open/closed state of the slide valve in Fig. 3.
FIG. 5 is a graph showing the capacity adjustment characteristics of the compressor of FIG. 3, and FIG. 6 is a diagram schematically illustrating the configuration of a conventional screw expander. 20 is a casing, 23 is a gas inlet, 24 is a gas outlet,
25 is an expansion process pressure equalization section, 27 is an external gas supply path, 2
8 is a gas outlet side pressure equalizing section, 29 is a slide valve, and 32 is a variable fixed valve. Patent applicant: Kobe Steel, Ltd. 1$11 Figure 2 Figure 3

Claims (1)

[Claims] 1. A gas outlet side pressure equalizing part communicating with the gas outlet is provided on the gas outlet side in the casing, and a gas expansion process part,
An expansion process pressure equalization section connected to a gas path for external gas supply is provided, and a predetermined open/close position of the gas outlet side pressure equalization section during normal operation and a fully closed position of the gas outlet side pressure equalization section during overload are provided. A variable fixed valve mechanism that can set two positions, and a slide valve mechanism that can adjust the opening and closing of the gas outlet side pressure equalizing section during steady operation and can adjust the opening and closing of the expansion process pressure equalizing section during overload. A slide valve type screw expander with a side stream.