The following relates to a turbomachine, in particular a turbocompressor, comprising at least one rotor which extends along an axis, comprising at least one axial high-pressure position, at least one axial low-pressure position, wherein, when the turbomachine is in operation, the pressure of a process fluid is higher at the high-pressure position than at the low-pressure position, at least one gas seal which seals, by means of seal gas, a gap between the rotor and a stator of the turbomachine, a preparation module which prepares process fluid, extracted from the high-pressure position at an extraction point, to give seal gas, which seal gas is supplied to the gas seal. The following further relates to a method for operating the turbomachine.
Turbomachines, in particular turbocompressors for combustible and/or toxic gases, are frequently sealed with dry gas seals, in particular dry gas seals. The seal gas for these gas seals is generally extracted from the pressure connection of the compressor, prepared, reduced in pressure and supplied to the gas seals. In the case of very high-pressure compressors with dry gas seals, it is difficult to acquire components for the function preparation (liquid separation, filtering, heating, pressure control). Furthermore, these components are very expensive.
Proceeding from the turbomachine mentioned in the introduction, embodiments of the invention reduce the investment cost for the preparation of the seal gas for the gas seal.
Indications of direction, such as axial, radial, tangential or circumferential direction, always refer unless otherwise stated to the axis of the rotor of the turbomachine.
The preparation module comprises a substantial part of the seal gas preparation from the process fluid to the seal gas. This includes at least the liquid separation or the filtering or the heating or the pressure control of the seal gas. By virtue of the arrangement, according to embodiments of the invention, of the preparation downstream of the control valve, the components of the preparation module can be configured for a lower pressure and are, for that reason at least, more cost-effective. In the case of particularly high compressor pressures, it is thus possible to eliminate acquisition problems for these components of the preparation module and to avoid special production runs therefor. This results in lower costs, a greater choice of suppliers and shorter supply times. An additional positive effect is that the risk potential is significantly reduced on account of the lower pressure in the preparation module, which plays an important role in the case of combustible or toxic gases and also with respect to costs.
Particularly expedient is the use of embodiments of the invention for a compressor, in particular a high-pressure compressor for pressures above 100 bar.
Particularly expediently, the sensor measures either the pressure behind the preparation module or a pressure difference across a throttle, such that the mass flow rate or volume flow rate of seal gas toward the gas seal is reliably controlled. Expediently, downstream of the control valve is a discharge line at a lower pressure, which can for example be shut off by a safety valve if, as a consequence of the pressure control or pressure difference control malfunctioning, the possibly toxic or combustible process fluid in the line downstream of the control valve exceeds the maximum permitted pressure and thereby risks escaping into the surroundings of the turbomachine. This low pressure can for example be the discharge line leading to a flare where the process fluid if combustible is flared off
Particularly expediently, the control unit comprises a pressure difference transmitter which controls a pressure difference, between the pressure of the extraction point of the process fluid and the pressure of the seal gas downstream of the preparation module, to a setpoint value. This setpoint value can be a setpoint value which is predefined instantaneously by a superordinate controller and which is dependent on the current operating conditions of the turbomachine.
The turbomachine preferably has a balancing piston, i.e. a gradation in the rotor R which ensures, by means of a shaft seal, that the pressures acting on the two sides of the gradation balance or reduce as far as possible the thrust of the turbomachine in rated operation. Furthermore, the chamber of the balancing piston is connected to the suction side of the turbomachine and thus the sealing pressures of the gas seals on the suction side and the pressure side are near identical. The pressure in the chamber of the balancing piston is only slightly higher, owing to the flow losses, than the pressure on the suction side and is therefore used as impulse pressure for the control. The process fluid extracted for seal gas via the extraction point at the high-pressure position can preferably be extracted at the pressure connection of the turbomachine in the region of this balancing piston and, according to embodiments of the invention, be supplied to the preparation module via the control valve. The invention is described in more detail below with reference to an exemplary embodiment and with reference to a drawing.
Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
In the event of the control valve CV malfunctioning, the situation of the control valve CV being fully open can arise. As a result, much more process fluid PF would flow in the direction of the preparation module SGM and the orifice plates TH and thus, on account of the resistance profile of the preparation module SGM and of the orifice plates TH, substantially increase the pressure upstream of the gas seals DGS, which can lead to the design pressure being exceeded. In order to guard against this malfunction, a safety valve SV, which opens at a start-to-leak pressure, is provided downstream of the control valve CV. The start-to-leak pressure is slightly above the maximum operational pressure downstream of the control valve CV. The components of the pipes PIP1, PIP2, the preparation module SGM, the control valve CV and the orifice plates TH are as a minimum configured for this start-to-leak pressure of the safety valve SV.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.
Number | Date | Country | Kind |
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10 2012 215 823.5 | Sep 2012 | DE | national |
This application claims priority to PCT Application No. PCT/EP2013/065685, having a filing date of Jul. 25, 2013, based on DE 102012215823.5 having a filing date of Sep. 6, 2012, the entire contents of which are hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/065685 | 7/25/2013 | WO | 00 |