JPH07217406A - Bypass line of expansion machine - Google Patents

Abstract

PURPOSE:To bypass gas from a first stage inlet to a nest stage inlet to which no foreign material is adhered in an expander composed of a plurality of expansion stages by forming a bypass line for compressed gas from the inlet of one expansion stage to the inlet of the next stage, in the case that foreign material is adhered only to the first stage. CONSTITUTION:In the case that a sectional area of a flow passage for gas is decreased through adhesion of foreign material to a blade of the first stage 1 of an expansion machine pressure is increased in the upper course of a turbine inlet line 8. A bypass line 3 having a valve 12 is therefore arranged. Pressure increase is prevented by feeding compressed gas through the bypass line 3 to a second stage inlet nozzle 6 at the second stage 2 of the next expander. Performance deterioration is prevented at the second stage 2 of the expansion machine to which no foreign material is adhered. Performance deterioration of whole of the expansion machine is suppressed to minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expander having a plurality of expansion stages for obtaining power by injecting compressed gas from a nozzle.

[0002]

2. Description of the Related Art In an expander that has been operating for a long period of time, foreign matter may adhere to a flow path through which compressed gas passes due to silica precipitation or the like. Since this foreign substance reduces the area of the gas flow path, if the operation is continued without changing the flow rate to be handled, the pressure on the inlet side rises, which affects the entire process. In order to prevent this pressure rise, the reduced performance requires a known bypass of the compressed gas. When compressed air is bypassed, performance will be reduced, such as a decrease in rotation speed and shaft power.However, conventionally, there are multiple expansion stages, and even if foreign matter adheres only to the first stage, compression on the inlet side will occur. Since the gas was released to the atmosphere or bypassed to the discharge side, the performance of all stages was degraded, that is, the performance was degraded more than necessary.

[0003]

Foreign matter often adheres to, for example, the blades of the first impeller of the expander stage. In this case, if the compressed air on the inlet side is bypassed to the discharge side, the performance of all stages of the expander will be deteriorated, so in order to minimize the performance deterioration, the handling flow rate of only the first stage should be reduced.
That is, it may be considered that the compressed gas is not bypassed to the discharge side, but is bypassed to the inlet side of the next expansion stage where no foreign matter is attached, and the gas handling flow rate of the subsequent stages is not reduced.

An object of the present invention is to prevent pressure rise on the inlet side of the expander by bypassing the compressed air at the inlet to the discharge side when foreign matter adheres to the gas flow path, and for the expander to have a plurality of stages. In the case where foreign matter is adhered only to the first stage, the performance of the expander is minimized by bypassing the inlet side of the first stage to the inlet side of the next stage where foreign matter is not adhered.

[0005]

To achieve the above object, the present invention provides an expander comprising a plurality of expansion stages,
When foreign matter adheres only to the first stage, a bypass line is provided from the first stage inlet side to the next stage inlet side.

[0006]

1 to 5 show an embodiment. 6 to 10 are graphs showing the operation according to the present invention.

Reference numeral 21 in FIG. 6 is a performance curve before foreign matter adheres, and 22 is a performance curve after foreign matter adheres. The initial operating point is 23, and when the performance deteriorates and the curve changes from 21 to 22, the operating point moves to 24. In this case, since the inlet pressure rises and affects each part of the plant, the compressed gas must be bypassed from the inlet side of the first expansion stage by the amount indicated by 26 to keep the pressure at the same as the initial operating point. I won't. At this time, the operating point is the point indicated by 25 in FIG.

As usual, when the compressed gas is released to the atmosphere,
Since the handling flow rate of the entire expander is reduced, the performance curve of the second expansion stage changes from 21 to 22 as shown in FIG. 7. In this case, the output of the expander changes from 23 to 25 in FIG. 8 in the first stage and from 23 to 27 in FIG. 9 in the second stage, and as a whole, as shown in FIG. From 23 to 27, the performance is significantly reduced.

With this structure, when foreign matter adheres and the gas flow passage area is reduced, if the gas on the inlet side is bypassed to the inlet side on the second stage, the operating point on the second stage is 23 in FIG. The output of the second expansion stage is still 23 in FIG. As a result, in the expander as a whole, as shown in FIG.
The output shifts to the point indicated by 25, and the performance deterioration of the expander can be minimized.

[0010]

FIG. 1 shows an embodiment of the present invention. FIG. 1 shows an operating system of an expander driven by compressed gas, and an embodiment is shown by taking this as an example. This operating system uses the expander 1
Stage 1, Expander 2nd stage 2, Bypass line 3, Heater 1
It consists of zero. 4 to 7 are nozzles of the expander, 8 is an inlet line of the expander, 9 is a discharge line, and 11 is a steam line sent to the heater. A valve 12 is attached to the bypass line. When foreign matter adheres to the blades of the first expansion stage or the like to reduce the gas flow passage area, the pressure rises upstream from the inlet line 8 and affects the entire process. Therefore, the bypass line 3 is provided to send the compressed gas to the inlet side of the next stage to prevent the pressure from rising. Bypassing to the inlet side of the heater 10 is to raise the temperature of the gas expanded by the valve 12. The reason why the bypass line is provided on the inlet side of the next stage is that foreign matter often adheres to the first stage of the expander, but since it rarely adheres to the next stage, it does not reduce the handling flow rate of the next stage. is there.

A system using a turbine instead of an expander is shown in FIG. Since no heater is used in the case of the turbine system, the system shown in FIG. 2 is used in the case of the turbine system.

FIG. 3 shows a conventional technique, which is an example in which a compressed gas is released to the atmosphere.

FIG. 4 shows an embodiment in which an instrumentation system is actually installed. By detecting the inlet pressure of the expander and providing a detection line 14, a control valve 15 and a pressure transmitter 16, a gas which is automatically bypassed is provided. Fig. 7 shows a system that allows the amount of P to be adjusted.

FIG. 5 shows a system capable of detecting the flow rate instead of the pressure and adjusting the amount of gas bypassed by the flow rate transmitter 18 and the control valve 15.

[0015]

According to the present invention, when foreign matter adheres to the compressed gas flow passage in the first stage of an expander having a plurality of expansion stages to reduce the flow passage area, the first stage inlet of the expander or the turbine. By bypassing from the side to the inlet of the second stage, it is possible to prevent performance deterioration of the second expansion stage where foreign matter does not adhere,
It is possible to minimize the deterioration of the performance of the expander as a whole.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a system diagram of a second embodiment of the present invention.

FIG. 3 is a system diagram of a conventional technique.

FIG. 4 is a system diagram of a third embodiment of the present invention.

FIG. 5 is a system diagram of a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of an inlet pressure and a flow rate according to the present invention.

FIG. 7 is an explanatory diagram of an inlet pressure and a flow rate of the present invention.

FIG. 8 is an explanatory diagram of a flow rate and an output according to the present invention.

FIG. 9 is an explanatory diagram of the flow rate and output of the present invention.

FIG. 10 is an explanatory diagram of the flow rate and output of the present invention.

[Explanation of symbols]

1 ... Expander (turbine) first stage, 2 ... Expander (turbine) second stage, 3 ... Bypass line, 4 ... First stage inlet nozzle, 5 ... First stage discharge nozzle, 6 ... Second stage inlet nozzle, 7
... second-stage discharge nozzle, 8 ... inlet line, 9 ... discharge line, 10 ... heater, 11 ... steam line, 12 ... valve.

Claims (1)

[Claims] 1. An expander system comprising a plurality of expansion stages, comprising a compressed gas bypass line from an inlet side of a certain expansion stage to a subsequent expansion stage inlet side of a subsequent expansion stage.