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MOUNTING ARRANGEMENT OF MECHANICAL SEALS ON AXIALLY SPLIT MACHINES

IP.com Disclosure Number: IPCOM000241123D
Publication Date: 2015-Mar-27
Document File: 4 page(s) / 146K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention proposes a design for seal chamber of an axially split pump that elaborates supercritical CO2. The design includes a one piece sleeve that is installed between seal chamber and cartridge of a dry gas seal (DGS). The design includes a frontal seal between the sleeve and the seal chamber. The frontal seal is pre-loaded by bolts between the sleeve and the seal chamber. Due to the frontal seal, the O-rings are not in contact with high pressure CO2 and therefore are not subjected to the risk of rapid gas decompression (RGD). Consequently, the O-rings are able to compensate discontinuities between the two halves of the seal chamber.

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MOUNTING ARRANGEMENT OF MECHANICAL SEALS ON AXIALLY SPLIT MACHINES

BACKGROUND

The present invention relates generally to an axially split machine and more particularly to a design for a seal chamber of the axially split machine.

A dry gas seal is installed on a multi-stage, axially split machine, such as, a centrifugal pump for supercritical CO2  or in general a mixture of liquefied or supercritical gasses. The seal chamber is divided into two halves, an upper half referred to herein as an upper case and a lower half referred to herein as a lower case. Manufacturing and assembly process generates axial and radial steps between the two halves. The gasket between the two halves of the pump creates another discontinuity. Figure 1 depicts the two halves of the seal chamber in the axially split machine. A portion of the seal chamber is bound in a red box in the Figure 1 which is enlarged and depicted in Figure 2 below.

Figure 1

Figure 2 depicts an elaborate view of the red box marked in Figure 1 of seal chamber in the axially split machine.

Figure 2

In a conventional technique, radial seals are utilized between a cartridge of dry gas seal (DGS) and a seal chamber. Radial seals are required to compensate discontinuities between the two halves. Also, the radial seals are required to be compatible with supercritical CO2. Elastomeric O-rings are utilized to compensate discontinuities. However, O-rings are subjected to rapid gas decompression (RGD) when operating with high pressure (HP) CO2, which is typical of pumps. Seals made up of RGD resistant material, such as, polytetrafluoroethylene (PTFE), are not able to compensate discontinuities. As a consequence, a radial seal between the cartridge of a DGS and a seal chamber of an axially split pump that elaborates high pressure CO2 is subject to possible damage of O-ring seals due to explosive decompression. Further, use of wet seals instead of dry gas seals in the conventional technique provides damage to the axially split pump. Figure 3 depicts conventional seal assembly in the axially split pump.

Figure 3

It would be desirable to have an efficient seal chamber design that prevents damage of the O-ring seals due to explosive decompression.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 depicts seal chamber in the axially split machine.

Figure 2 depicts an elaborate view of seal chamber in the axially split machine.

Figure 3 depicts conventional seal assembly in the ax...