RU2066008C1 - Method of gas dynamic sealing - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: gas is sucked from the chamber for collecting leakages by means of a compressor. The chamber for collecting leakages is in communication with the collector of low gas pressure through a pressure regulator. The pressure regulator is connected with the working space of a machine through a feedback. The chamber is filled with an additional amount of gas of low pressure to maintain in the chamber an atmospheric pressure. EFFECT: simplified method. 3 cl, 1 dwg

Description

 The invention relates to methods for sealing a shaft of a vane machine, including various structural solutions and sealing elements.

 The most perfect and widely used at present are gas-oil seals of mechanical and other types / 1 /.

 The operation of such seals is based on the excess of the oil pressure in the seal assembly over the gas pressure, which is supported by a special regulator. In this case, some of the sealing oil enters the gas, and then into the gas separator and again participates in the compaction process. Such a system requires a pump, a tank and a heat exchanger, i.e. autonomous oil supply system. On machines of higher power, the use of such a system of course leads to a complication of the design, but it is not decisive. On low-power machines of 50 300 kW, the traditional gas-oil seal makes the design and maintenance of the machine so complicated that it may raise the question of whether it is worth using.

 The proposed method, like the existing ones, provides for a shaft seal assembly containing a chamber, from which the shaft exits through a wall, on the outside of which is in atmospheric air, and on the inside there is a sealing agent.

 The objective of the invention is to simplify the design of machines of medium and high power and the creation of highly reliable and blade machines of low power.

 The technical result is achieved in that the sealing agent is not an additional agent lubricating oil or other substance, but the same gas, which is compressed or expanded in a spatula, but at a pressure equal to atmospheric. This eliminates the possibility of gas leakage from the machine, as well as the penetration of air into the process gas. This is achieved due to the fact that up to 5 7 low-pressure process gas is constantly supplied from the machine to the special chamber from which the shaft exits while working from the machine through a pressure regulator to maintain the gas pressure at the outlet close to atmospheric pressure, and an additional compressor constantly sucks gas from chamber, compresses it to a pressure of 0.05 MPa above the lower pressure of the process gas in the blade machine. In this gas-dynamic method, a certain energy is used for the purpose of compaction, which certainly slightly reduces the energy efficiency of the blade machine, but its design is greatly simplified and highly reliable compaction is ensured.

 The use of gas-dynamic compaction opens up great opportunities for creating highly reliable blade machines of low power and can significantly simplify the design of machines of medium and high power.

 Such a seal can be most effectively used, for example, when creating a blade air motor using the energy of the differential pressure of natural gas at gas distribution (GDS) and compressor stations (CS) to drive an electric generator.

 This will make it possible to use “brass energy, that is, energy dissipated on the HRS and CS throttles during the expenditure of heat energy for heating the gas before throttling, to generate electric energy without the consumption of energy resources and negative impact on the environment.

 The available energy for these purposes at the gas distribution stations and compressor stations of Russia is about 50 billion kWh per year, which is equivalent to 20 25 million tons of fuel.

 The implementation of the proposed method of gas-dynamic sealing of the shaft of a vane machine is illustrated in the drawing.

 For example, a blade machine is a turboexpander. The collector 1 through the valve 2 by a pipe equipped with a safety valve 3 is connected to a turboexpander 4, the shaft of which through the labyrinth seal 5 and the chamber 6 for collecting leaks through the cuff 7 out. The chamber 6 is connected to a compressor 8, having a mechanical connection with the shaft of the turboexpander or gas connection with a high and low pressure manifold when using an ejector. In addition, the chamber 6 is connected by a pipeline on which a pressure regulator-regulator 9 is connected to a low-pressure manifold 10, and a pressure regulator-gas regulator is connected by a gas connection to the working cavity of the machine.

 The proposed seal works as follows.

 Gas from the high-pressure manifold through the valve 2 through a pipeline equipped with a safety valve 3, enters the turbine expander 4, where a certain differential is triggered and the power on the shaft develops.

 In the gap between the shaft and the housing, some of the gas under reduced pressure through the labyrinth seal 5 enters the chamber 6. At the outlet of the shaft from the chamber 6, a sealing sleeve 7 is installed.

 The essence of the proposed sealing method is to maintain in the chamber 6 a pressure equal to atmospheric due to suction of gas from it. This is done using a compressor 8, which is driven by a turboexpander shaft or gas connection in the case of an ejector. To ensure that the amount of gas sucked off by the compressor 8 from the chamber 6 and the gas flow into it / to maintain a pressure equal to atmospheric / matches, in addition to uncontrolled gas leakage through the labyrinth seal, an adjustable gas supply from the low pressure manifold 10 is provided through the pipeline through the pressure regulator 9 / e.g. membrane type / gas feedback.

 As a compressor, an ejector is used, connected to a high-pressure gas manifold for supplying working gas in communication with a chamber for suctioning gas leaks, and the gas outlet from the ejector is connected to a low-pressure gas collector.

 By increasing the pressure of the gas being sealed, it is possible to carry out step-by-step leakage diversion. This is done from several leakage collection chambers located along the gas, using ejectors connected in series. In this case, each of the ejectors is connected to a high-pressure gas collector for supplying a working gas, and the output of the first ejector along the way is connected with a subsequent leakage collection chamber, from which it is sucked off by the subsequent ejector.

 The application of the invention allows the creation of highly reliable blade-type pneumatic engines of turbo-expanders for driving an electric generator and other energy consumers using pressure energy of natural gas.

Claims (3)

 1. The method of gas-dynamic compaction of a predominantly vane machine, including the removal of gas through the gap between the shaft and the machine body and directing it into the labyrinth to reduce its pressure, supplying a gas leakage collection chamber, withdrawing from this chamber and sealing the shaft exit from the latter, characterized in that the gas is removed from the leakage collection chamber by suction using a compressor, and at the same time, the leakage collection chamber is communicated through a gearbox-regulator by feedback gas communication with the working cavity of the machine and the supply to the chamber additional low-pressure gas to maintain atmospheric pressure in the chamber.  2. The method according to claim 1, characterized in that the compressor uses an ejector connected to a high-pressure gas manifold for supplying a working gas in communication with a chamber for suctioning gas leaks, and the gas outlet from the ejector is connected to a low-pressure gas manifold.  3. The method according to claim 2, characterized in that, as the pressure of the gas being compacted increases, leaks are stepped away from several leakage collection chambers located along the gas using ejectors connected in series, each of which is connected to a high-pressure gas manifold for supplying working gas , and the output of the first is communicated with a subsequent leakage collection chamber, from which it is sucked off by a subsequent ejector.