Fluid energy machine having a tandem dry gas seal

Patent metadata

Field	Value
Publication number	US-2017191486-A1
Application number	US-201515314592-A
Country	US
Kind code	A1
Filing date	Jun 16, 2015
Priority date	Jun 18, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

A fluid energy machine having a rotor, with a casing that separates an interior from an exterior, having at least one shaft seal for sealing a gap between the rotor and casing. The shaft seal is a tandem dry gas seal, having an inner and outer seal. The outer seal has a first sealing gas feed, which opens into the gap axially between the outer and inner seal. The shaft seal has a primary discharge between the inner and outer seal, which extracts primary discharge fluid from the gap. The first sealing gas feed has a first control member for controlling the flow rate of the sealing gas. The primary discharge has a second control member for controlling the flow rate of a primary discharge fluid. The first and second control members are matched such that the first pressure is adjusted to a first pressure setpoint.

First claim

1 . A fluid energy machine, comprising:
a rotor extending along an axis, a casing, wherein the casing separates an interior from an exterior, at least one shaft seal for sealing a gap between the rotor and the casing, wherein the shaft seal is designed as a tandem dry gas seal, wherein the tandem dry gas seal comprises an inner seal and an outer seal, wherein the outer seal has a first sealing gas feed, which opens into the gap axially between the outer seal and the inner seal, wherein the shaft seal has a primary discharge between the inner seal and the outer seal, which discharges a primary discharge fluid from the gap, wherein the first sealing gas feed has a first control member for controlling the flow rate of the sealing gas out of a sealing gas system, wherein the primary discharge has a second control member for controlling the flow rate of a primary discharge fluid, wherein the first control member and the second control member are matched to one another in such a way that the first pressure is adjusted to a first pressure setpoint by a procedure in which, in a first step, the open position of the second control member is first of all controlled to adjust the first pressure and the first control member is closed, and, in a second step, if the first pressure remains lower than the first setpoint pressure with the second control member closed, the first control member is opened while the second control member is closed, and the open position of the first control member is controlled to adjust the first pressure until the first pressure has been adjusted to the first setpoint pressure, and, in a third step, if the first pressure remains higher than the first setpoint pressure with the first control member closed, the first step is initiated again.

2 . The fluid energy machine as claimed in claim 1 ,
wherein the shaft seal has a pressure measuring point between the inner seal and the outer seal or in the primary discharge, which measures a first pressure indirectly or directly in the gap.

3 . The fluid energy machine as claimed in claim 2 , further comprising:
a control unit which is connected to the pressure measuring point, the first control member and the second control member, wherein the control unit is designed in such a way that the first pressure is adjusted to a first pressure setpoint by a procedure in which, in a first step, the open position of the second control member is first of all controlled to adjust the first pressure and the first control member is closed, and, in a second step, if the first pressure remains lower than the first setpoint pressure with the second control member closed, the first control member is opened while the second control member is closed, and the open position of the first control member is controlled to adjust the first pressure until the first pressure has been adjusted to the first setpoint pressure, and, in a third step, if the first pressure remains higher than the first setpoint pressure with the first control member closed, the first step is initiated again.

4 . The fluid energy machine as claimed in claim 1 ,
wherein the control of the control members is accomplished by means of pressure setpoints that can be set directly at the control members.

5 . The fluid energy machine as claimed in claim 1 ,
wherein a higher pressure setpoint is set at the second control member than at the first control member.

6 . The fluid energy machine as claimed in claim 1 ,
wherein, toward the interior, a first labyrinth seal for sealing the gap is assigned to and adjacent to the outer seal.

7 . The fluid energy machine as claimed in claim 6 ,
wherein the first sealing gas feed opens into the gap axially between the outer seal and the first labyrinth seal.

8 . The fluid energy machine as claimed in claim 6 ,
wherein the primary discharge opens into the gap axially between the first labyrinth seal and the inner seal.

9 . The fluid energy machine as claimed in claim 3 ,
wherein the control unit issues an alarm if the first pressure falls below an alarm pressure.

10 . The fluid energy machine as claimed in claim 3 ,
wherein the control unit brings about shutdown of the fluid energy machine if the first pressure falls below a shutdown pressure.

11 . The fluid energy machine as claimed in claim 1 ,
wherein, toward the interior, a second labyrinth seal for sealing the gap is assigned to and adjacent to the inner seal.

12 . The fluid energy machine as claimed in claim 1 ,
wherein the inner seal has a second sealing gas feed, which opens into the gap axially toward the interior, adjacent to the inner seal.

13 . The fluid energy machine as claimed in claim 12 ,
wherein the second sealing gas feed opens into the gap axially between the inner seal and the second labyrinth seal.

14 . The fluid energy machine as claimed in claim 12 ,
wherein the first sealing gas feed is connected to the second sealing gas feed in such a way that changing the pressure of the sealing gas from the sealing gas system also brings about a change in the pressure of the first sealing gas feed.

15 . The fluid energy machine as claimed in claim 12 ,
wherein the first sealing gas feed and/or the second sealing gas feed each have a restrictor element, by means of which the flow of the sealing gas flowing into the gap can be limited to a maximum flow.

16 . A method for operating a fluid energy machine wherein the fluid energy machine comprises a rotor extending along an axis, a casing, wherein the casing separates an interior from an exterior, at least one shaft seal for sealing a gap between the rotor and the casing, wherein the shaft seal is designed as a tandem dry gas seal, wherein the tandem dry gas seal comprises an inner seal and an outer seal, wherein the outer seal has a first sealing gas feed, which opens into the gap axially between the outer seal and the inner seal, wherein the shaft seal has a primary discharge between the inner seal and the outer seal, which discharges a primary discharge fluid from the gap, wherein the first sealing gas feed has a first control member for controlling the flow rate of the sealing gas out of a sealing gas system, wherein the primary discharge has a second control member for controlling the flow rate of a primary discharge fluid, the method comprising:
adjusting the first pressure to a first pressure setpoint by a procedure in which, in a first step, the open position of the second control member is first of all controlled to adjust the first pressure and the first control member is closed, and, in a second step, if the first pressure remains lower than the first setpoint pressure with the second control member closed, the first control member is opened while the second control member is closed, and the open position of the first control member is controlled to adjust the first pressure until the first pressure has been adjusted to the first setpoint pressure, and, in a third step, if the first pressure remains higher than the first setpoint pressure with the first control member closed, the first step is initiated again.

17 . The method for operating a fluid energy machine as claimed in claim 16 ,
wherein the shaft seal has a pressure measuring point between the inner seal and the outer seal or in the primary discharge, which measures a first pressure indirectly or directly in the gap, wherein a control unit is connected to the pressure measuring point, the first control member and the second control member.

18 . The method for operating a

Assignees

• Siemens Ag

Inventors

• Alfes Ludger

Classifications

• F04D17/10

  for compressing or evacuating · CPC title

• F04D29/104 Primary

  the sealing fluid being other than the working fluid or being the working fluid treated · CPC title

• F04D29/4206

  especially adapted for elastic fluid pumps · CPC title

• F04D27/002

  by varying geometry within the pumps, e.g. by adjusting vanes · CPC title

• F04D29/284

  for compressors · CPC title