Device for expanding steam and method to control such a device

Patent metadata

Field	Value
Publication number	US-10174638-B2
Application number	US-201515312038-A
Country	US
Kind code	B2
Filing date	May 11, 2015
Priority date	May 19, 2014
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A device for expanding steam, whereby this device comprises an expander with an inlet that is connected to an inlet pipe and an outlet that is connected to an outlet pipe, whereby the inlet pipe is provided with an inlet valve and the outlet pipe is provided with an outlet valve for isolating the space between the valves, by closing these valves when the expander is not operating, whereby the device is provided with a steam supply that conditions the space between the valves when the expander is not operating, such that no air can penetrate into the space.

First claim

The invention claimed is:

1. A device for expanding steam, whereby this device comprises an expander with a rotor for converting steam energy into mechanical energy on the shaft of the rotor, whereby this expander comprises an inlet that is connected to an inlet pipe for steam and an outlet that is connected to an outlet pipe for steam, whereby the inlet pipe is provided with an inlet valve and the outlet pipe is provided with an outlet valve for isolating the space between the inlet valve and the outlet valve, that contains the expander, by closing these valves when the expander is not operating, wherein the device is further provided with a steam supply that conditions the aforementioned space between the inlet valve and the outlet valve when the expander is not operating, in such a way that no air can penetrate into the aforementioned space and, whereby the steam supply is formed by a steam supply pipe that taps off steam from the inlet pipe upstream from the inlet valve and/or the outlet pipe downstream from the outlet valve.

2. The device according to claim 1 , wherein the steam supply is supplied with a supply valve that is connected to a controller that opens the supply valve when the expander is taken out of operation and which closes the supply valve again when the expander is put back in operation.

3. The device according to claim 2 , wherein the supply valve is a control valve, with which the overpressure in the space between the inlet valve and the outlet valve can be controlled.

4. The device according to claim 1 , wherein the expander is provided with a drainpipe for draining off condensate.

5. The device according to claim 4 , wherein the drainpipe is provided with a condensate separator or a controlled valve.

6. The device according to claim 1 , wherein the steam supply pipe forms a direct bypass across the inlet valve and/or across the outlet valve.

7. The device according to claim 2 , wherein the device is provided with at least one pressure sensor and/or temperature sensor whose signal is connected to the controller and on the basis of which the controller will open and close the supply valve more or less to obtain an overpressure in the space between the inlet valve and the outlet valve.

8. The device according to claim 7 , wherein the controller is such that the overpressure is kept at a set value.

9. The device according to claim 1 , wherein the expander is a screw expander.

10. The device according to claim 1 , wherein means are provided that prevent the rotor of the expander from being driven by the steam supply while the expander is not operating.

11. The device according to claim 2 , wherein the aforementioned means consist of the supply valve allowing through a flow that is insufficient for driving the rotor of the expander.

12. The device according to claim 1 , wherein the means consist of steam being supplied to the aforementioned space, both at the level of the inlet, and of the outlet.

13. The device according to claim 10 , wherein the aforementioned means are formed by a brake on the shaft of the rotor that is activated while the expander is not operating and is deactivated when the expander is operating.

14. The device according to claim 13 , wherein the brake is a mechanical brake.

15. The device according to claim 13 , wherein the rotor is mechanically coupled to a generator that, while the expander is not operating, is used as a brake by applying a direct current to the windings of the generator.

16. A method for controlling a device or expanding steam, whereby this device comprises an expander with an inlet that is connected to an inlet pipe and an outlet that is connected to an outlet pipe and a rotor for converting steam energy into mechanical energy on the shaft of the rotor, whereby the method comprises the step of closing the inlet valve and the outlet valve when the expander is not operating, wherein during the aforementioned step the method consists of supplying steam to the closed space between the inlet valve and the outlet valve that contains the expander and, whereby for the steam supply to the aforementioned space, steam is tapped off from the inlet pipe and/or from the outlet pipe.

17. The method according to claim 16 , wherein condensate that occurs in the aforementioned space is removed at least while the expander is not operating.

18. The method according to claim 16 , wherein the pressure in the aforementioned closed-off space, that contains the expander, and the ambient pressure are measured, the difference between the two pressures is determined, and that on the basis of the aforementioned difference the steam supply is increased or decreased to obtain an overpressure in the aforementioned space.

19. The method according to claim 16 , wherein it prevents the rotor of the expander from being driven by the steam supply while the expander is not operating.

20. The method according to claim 19 , wherein insufficient steam is supplied to the aforementioned space to drive the rotor of the expander.

21. The method according to claim 19 , wherein steam is supplied to both the inlet and the outlet of the expander.

22. The method according to claim 19 , wherein the shaft of the rotor is braked while the expander is not operating and is left free when the expander is operating.

Assignees

• Atlas Copco Airpower Nv

Inventors

• Van Campfort Kris
• Hubin Kristof Pascal

Classifications

• H02P3/025

  holding the rotor in a fixed position after deceleration · CPC title

• F01K7/16

  the engines being only of turbine type (the engines using steam of critical or overcritical pressure F01K7/32; the engines being of extraction or non-condensing type F01K7/34) · CPC title

• F01K13/02 Primary

  Controlling, e.g. stopping or starting · CPC title

• H02K7/102

  with friction brakes · CPC title

• H02P3/24

  by applying DC to the motor · CPC title