RU2731262C1 - Steam screw machine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to steam screw machines. Machine comprises high-pressure housing 1 with inlet branch pipe 2, low-pressure housing 3 with outlet branch pipe 4, screw rotors parallel installed on pairs of support bearings 7 arranged in both housings 1 and 3, kinematically connected to each other by means of synchronizing gears 9 and equipped with thrust bearings 8 arranged in housing 1. Rotors are equipped with unloading disks 10 arranged in housing 1 with formation of unloading chambers 12 communicated via channels 13 with branch pipe 4. Between bearings 7 and the screw part of the rotors there are double end seals 14. At the junction of housings 1 and 3 there is bottom 15 with holes 16 for shafts of rotors and inlet opening 17. Separating diaphragms are installed in housings 1, 3 between each bearing 7 and seal 14 and make non-contact seals 20, 21 with rotors. Each diaphragm is made of two diaphragms 18 and 19, spaced apart to form annular volume 22 between them. Each volume 22 is equipped with hole 23 for supply of compressed air into it.

EFFECT: invention is aimed at improving operating characteristics of the machine, improving operating reliability during start-up and shutdown periods.

1 cl, 3 dwg

Description

The invention relates to the field of power engineering, namely to devices for steam screw machines (PVM) operating on water steam.

From the prior art, FDA is known (RF patent No. 2319840, F01C 1/16, published 03/20/2008), containing a high-pressure casing (HPC) with an inlet for supplying high-pressure steam, a low-pressure casing (LPC) with an outlet for low-pressure steam outlet, lead and driven screw rotors, installed in parallel on support bearings located in pairs in the HPC and LPC, having helical teeth in the middle part, connected to each other by means of synchronizing gears and equipped with unloading discs placed in the HPC bores with the formation of unloading cavities connected with the outlet pipe, and the HPC and LPC are interconnected by means of a centering bottom located at the high-pressure end of the rotors.

The disadvantage of the known FDA is the possibility of oil getting from the cavity of the support bearings into the steam cavity and mixing water with the lubricating oil, thereby deteriorating the properties of the oil.

The closest technical solution is a FDA (RF patent No. 2464427, IPC F01C 1/16, published on 20.10.2012), containing a pressure build-up pump with an inlet for supplying high-pressure steam, LPC with an outlet for removing low-pressure exhaust steam, leading and driven rotors, mounted in parallel on support bearings placed in pairs in the HPC and LPC, connected to each other by means of synchronizing gears, having helical teeth in their middle part, meshing and equipped with double end seals, as well as unloading discs located in the HPC, and the ends The discs facing the helical teeth are in communication with the inlet pipe, and the opposite ends are connected with the outlet pipe, separating diaphragms are installed between the support bearings and end seals to form gaps with the rotors and with end seals of cavities communicated with the atmosphere by means of drain pipes. The diaphragm seals have oppositely directed oil and water-draining threads. The shafts in the areas where the diaphragms form gaps with the rotors have a smooth surface.

A feature of the known FDA is a significant duration of the start and stop periods due to the need for its (FDA) pre-start heating and cooling after shutdown. During the indicated periods, it is not allowed to stop the supply of lubricating oil, which also acts as a cooling liquid, and barrier water in mechanical seals. Poor diaphragm seal performance can cause contamination of the lubricating oil with water and / or the drained seal water from the lubricating oil.

The disadvantage of the known FDA is the low efficiency of the separating diaphragms during the periods of starting and stopping the FDA due to the disappearance of the pumping effect caused by the rotation of the shafts, which leads to a decrease in the reliability of the machine.

The objective of the invention is to improve the reliability of the FDA. The technical result of the invention is to improve the operational characteristics of the FDA by eliminating the watering of the lubricating oil and oily water leaks from the end seals.

The problem of the invention is solved and the technical result is achieved by a steam screw machine comprising a high-pressure casing with an inlet for supplying high-pressure steam, a low-pressure casing with an outlet for removing low-pressure steam, leading and driven screw rotors mounted in parallel on paired in both casings support bearings, kinematically interconnected by means of synchronizing gears and equipped with thrust bearings located in the high-pressure housing, and the leading and driven screw rotors are equipped with unloading discs located in the bores of the high-pressure housing with the formation of relief cavities communicated through channels with the outlet pipe between support bearings and the screw part of the rotors are equipped with double mechanical seals, and at the junction of the high and low pressure housings there is a bottom with holes for rotor shafts and an inlet window, also in housings of high and low pressure pressure between each support bearing and the mechanical seal, separating diaphragms are installed, forming contactless seals with the rotors, in which, unlike the prototype, each separating diaphragm is made of two diaphragms spaced apart from each other to form an annular volume between them, and each annular volume is equipped with an opening for feeding compressed air into it.

The essence of the invention is illustrated by drawings, where FIG. 1 shows a section of the FDA in a vertical plane passing through the axis of the driving rotor, FIG. 2 is an enlarged view of A in FIG. 1, and in FIG. 3 - section of the FDA in a horizontal plane passing through the longitudinal axes of the driving and driven rotors,

The proposed FDA contains HPC 1 with inlet 2 for high pressure steam supply, LPC 3 with outlet 4 for low pressure steam removal, 5 and 6 driven screw rotors. Rotors 5 and 6 are installed in parallel on the support 3 located in pairs in HPC 1 and LPC

bearings 7, equipped with thrust bearings 8, placed in HPC 1, are kinematically connected to each other by means of synchronizing gears 9. Rotors 5 and 6 are also equipped with unloading discs 10, placed in bores 11 of HPC 1 with the formation of unloading cavities 12, communicated with the outlet pipe 4 by channels 13, and double mechanical seals 14. At the junction of HPC 1 and LPH 3 there is a bottom 15, in which holes 16 are made for rotors 5, 6 and an inlet window 17. In HPC and LPV between support bearings 7 and double mechanical seals 14 two separating diaphragms 18 and 19, which form contactless seals 20 and 21 with the rotors. The said separating diaphragms are spaced apart to form an annular volume 22 between them, said annular volume being provided with a hole 23 for supplying compressed air. Annular volumes 24 are formed between the separating diaphragms 18 and the double mechanical seals 14, which in the lower part communicate with the atmosphere through openings 25.

PVM works as follows.

The high-pressure steam through the inlet 2 and the inlet port 17 enters the cavity formed by the teeth of the rotors 5, 6 and the bores of the LPC 3, expands, increasing the specified cavity, rotating the rotors 5, 6 and providing mechanical power on the rotors. The radial and axial forces arising on the rotors 5 and 6 are taken up by the support 7 and thrust bearings 8, while the axial forces caused by the action of steam on the screw parts of the rotors are partially compensated by the axial forces of the opposite direction acting on the discharge discs 10. Contactless rotation of the rotors 5 and 6 is provided by synchronizing gears 9. The generated power from the shaft of the driving rotor is transmitted through the clutch to the driven mechanism.

During the operation of the FDA, as well as during the periods of heating and cooling, before starting and after the FDA is stopped, it is supplied with lubricating oil and barrier water.

Lubricating oil is supplied to bearings 7 and 8 through holes 26 and discharged through holes 27. Isolation of oil cavities on the side of mechanical seals and prevention of contamination of the drained barrier water is provided by contactless seals 21 formed by separating diaphragms 19.

The barrier water in the double mechanical seals 14 is supplied through the holes 28 and is discharged through the holes 29. The penetration of the barrier water leaks into the oil cavities is prevented by the contactless seals 20 formed by the separating diaphragms 18, and the leaks themselves flow through the holes 25 into the drain.

Seals 20 and 21, without additional measures, do not provide complete sealing of oil cavities and cavities into which leakage of barrier water gets, especially during the periods of starting and stopping the FDA. Therefore, according to the invention, the supply of compressed air through the holes 23 to the annular volumes 22 is provided, which provides a back pressure that prevents leakage of barrier water and oil through the seals 20 and 21 even in the absence of rotation of the FDA shafts.

Thus, the proposed FDA design allows improving its operational characteristics, as well as increasing the reliability of its operation during start-up and shutdown periods.

Claims (1)

A screw steam engine containing a high-pressure housing with an inlet for supplying high-pressure steam, a low-pressure housing with an outlet for removing low-pressure steam, leading and driven screw rotors mounted in parallel on support bearings located in pairs in both housings, kinematically connected to each other by means of synchronizing gears and equipped with thrust bearings located in the high-pressure housing, and the driving and driven screw rotors are equipped with unloading discs located in the bores of the high-pressure housing with the formation of unloading cavities communicated through channels with an outlet pipe, between the support bearings and the screw part of the rotors are installed double mechanical seals, and at the junction of the high and low pressure housings there is a bottom with holes for the rotor shafts and an inlet window, also in the high and low pressure housings between each support bearing and the mechanical seal at separating diaphragms are formed, forming contactless seals with the rotors, characterized in that each separating diaphragm is made of two diaphragms, spaced apart to form an annular volume between them, and each annular volume is equipped with an opening for supplying compressed air to it.

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