GB2532870A

GB2532870A - Mechanical seal support system

Info

Publication number: GB2532870A
Application number: GB1519621.5A
Authority: GB
Inventors: Stephenson Heath; Smiddy John; Harte Paul
Original assignee: AES Engineering Ltd
Current assignee: AES Engineering Ltd
Priority date: 2014-11-06
Filing date: 2015-11-06
Publication date: 2016-06-01
Anticipated expiration: 2035-11-06
Also published as: GB2532870B; US9845885B2; US20160131261A1; GB201519621D0; GB201419795D0

Abstract

The system for use with a seal used with rotating equipment. The system includes a pressure vessel 1, a number of inlets 7, connecting pipe work between a seal 2 and the inlets such that it encompasses the vessel. The system also includes equipment to allow the fluid flow through the system to be altered. The flow of fluid may be directed independently to one or more sections of the system. It may be possible to replace the pressure vessel whilst allowing the continued operation of the rotational equipment. There may be two methods of operations which are a thermosyphon or flush to drain system. The system may include clean in place elements such as a spray ball. Also claimed is a method of operating a seal support system.

Description

MECHANICAL SEAL SUPPORT SYSTEM

Field of the Invention

This invention relates to seal support systems and especially systems which are used with mechanical seals for the containment of process fluid in typically clean environments.

Background to the Invention

Rotating equipment is an industry term which covers a wide range of different machinery, including pumps. In nearly all forms of rotating equipment some form of mechanical seal is used to ensure that product or contaminants do not migrate unintentionally. Within a pump, a mechanical seal is used to seal the pump product in the volute casing whilst allowing the shaft to rotate.

For a mechanical seal to allow rotation whilst sealing the volute casing, it has to create a sealed path between the casing and the shaft. This is achieved by using a rotary seal face, which is coupled to the shaft, and a stationary seal face, which is coupled to the housing. These two faces are manufactured with high tolerance flat faces and are energised together in order to create a seal. So as to ensure that the faces don't wear out, fluid is allowed to pass between the seal faces to reduce friction. This fluid typically escapes to atmosphere as a vapour or is absorbed into the pumped product.

In many applications it is a requirement that a double mechanical seal is used, which includes an additional set of sealing faces thus creating an internal cavity. The purpose of this is so that a buffer or barrier fluid may be used to regulate the operating environment of the seal. Typically, these plans follow those that are laid out by the American Petroleum Institute and are referred to as API plans.

Two common plans that are used are Plan 53a and Plan 62. Plan 62 is where a buffer/barrier fluid is piped directly into the internal cavity of a double mechanical seal and then out to drain and is sometimes referred to as a flush-to-drain system. This plan ensures that any product which passes across the seal faces is washed away but does result in a very large expenditure in buffer/barrier fluid. Plan 53a utilises a pressure vessel to provide a buffer/barrier fluid to the internal cavity of the seal and the Thermosyphon effect to ensure cooler fluid is passing through the seal. Thermosyphon systems are significantly cheaper to run but they do have the downside of potentially harbouring the build up of dirt and product.

In industry where it is necessary to ensure that any build up of product or dirt is avoided, it is common to use a Clean In Place procedure, otherwise known as CIP. This is where a spray ball is used to distribute a cleaning fluid to all product contacting surfaces within a vessel or system. CIP procedures are typically completed during shut down times or when the machinery is not running, as they would otherwise impede or affect production.

In Plan 62, there is little need for CIP procedures as the seal and the associated pipe work is inherently cleaned via the constantly running of buffer fluid.

In a Plan 53a, it is known that a CIP procedure can negate the potential for product and dirt to build up inside the pressure vessel and associated equipment. However, it is not possible to run the procedure during operation, as the vessel would need to be drained and thus would not be able to operate accordingly.

Statements of the Invention

According to the present invention there is provided a seal support system for use in conjunction with a mechanical seal installed on a piece of rotating equipment which comprises a pressure vessel, a number of fluid inlets and connecting pipe work between the fluid inlets and the mechanical seal, such that it encompasses the pressure vessel and such equipment as to allow the fluid flow through the system to be altered.

Preferably, the flow of fluid from one or more of the fluid inlets may be directed independently to one or more sections of the system therefore enabling the potential to run one or more functions of the system separately and/or in parallel. This would allow for the system to be able to maintain functionality whilst completing additional procedures set up to ensure continued clean running of the associated equipment.

Preferably, the flow of fluid from one or more of the fluid inlets flows, whether directly or indirectly, to and passes through the mechanical seal. Normal operation of the system would be to provide fluid to the mechanical seal so as to maintain an optimum running environment. Ideally, during additional operations it would be advantageous to be able to maintain the optimum running environment around the seal.

Preferably, there is provided such elements as to allow the method by which fluid is supplied to the mechanical seal to be altered as appropriate. Defining multiple methods to provide fluid to the mechanical seal allows for different aspects of said system to be isolated or repurposed.

Preferably, there are multiple methods of operation defined as primary, secondary, and, but not limited to, tertiary. More than one method of operation allows for additional functions for the purposes of ensuring more effective operation of the overall system.

Preferably, one of the methods of operation allows for the operational state of the pressure vessel to be altered whilst allowing for the continued operation of said rotational equipment. Wherein, such states may include cleaning and draining cycles for the purposes of reducing and negating the build up of foreign contaminants and where such operations to the effect outlined above are run without the operation of said rotating equipment being affected.

Preferably, one of the methods of operation allows for specific aspects of the system to be made redundant to the continued operation of said rotational equipment. It is deemed advantageous to be able to remove said equipment, such as the pressure vessel, for detailed inspection, sterilisation, refurbishment or other activities as may be required.

Preferably, there is included, but not limited to, a primary and secondary method of operation which may be characterised in the primary case by a thermosyphon system and in the secondary case by a flush to drain system. Additional methods of operation may include routines which cover the draining and flushing of specific elements of the system as well as different modes of operation to do with the running of the mechanical seal and/or system.

Preferably, such elements that are provided for the purpose of alternating between primary and secondary operation are defined as being capable of being controlled through non-manual means. Such elements would be able to be activated individually or in multiple permutations such that different operations could be performed and additionally the method by which said elements are controlled may include onsite and remote methods. Such non-manual means would include, but is not limited to; such methods as electrically actuated solenoid valves and pneumatically actuated valves.

Preferably, there is included in the system a means by which the pressure may be determined and where such information may be used to inform control mechanisms. Wherein, the method by which the pressure is determined is defined as a pressure switch and such that in certain operations the increasing pressure may be used to trigger a change thus alters the current function of the system.

Preferably, there is provided as part of the system such elements as to allow for cleaning procedures to be carried out. Such cleaning procedures as flushing and spraying of cleaning fluid through part or all of the system and wherein may be included distribution elements such as but not limited to, spray balls.

Preferably, there is provided a method to drain excess fluid from the system wherein said method is utilised as part of specific functions of the system, such as cleaning operations.

Preferably, there is provided a means of negating pressure build up when required. Wherein the pressure vessel may be temporarily converted to a non-pressure retaining container as is required.

Description of the drawings

The accompanying drawings are as follows: Figure 1 is a Piping & Instrumentation Diagram of the system of invention in one method of operation, wherein the system is run as a Thermosyphon.

Figure 2 is a Piping & Instrumentation Diagram of the system of invention in an alternative method of operation, wherein the mechanical seal is run in a flush to drain set up and the pressure vessel is being cleaned.

Figure 3 is a Piping & Instrumentation Diagram of the system of invention in a further alternative method of operation, wherein the mechanical seal is run in a flush to drain set up and the pressure vessel is being refilled.

Detailed description of the Invention

The invention will now be described, by way of example only, with reference to the accompanying drawings.

Referring to Fig. 1 of the accompanying drawings, there is shown a pressure vessel 1, which connects to a mechanical seal 2 through feed port 3 and return port 4 and by feed pipe 5 and return pipe 6 such that a closed loop is formed between the mechanical seal 2 and the pressure vessel 1.

In one method of operation, fluid enters through supply port 7 and passes through a non return valve 8, a pressure regulator 9, a flow indicator 10, normally open solenoid fill valve 11 and where is also included a pressure gauge 12. As fluid enters the pressure vessel 1 it pressurises the volume of gas present in the pressure vessel 1 and continues to fill up until the internal pressure is equal to the set point of the pressure regulator 9 and the final volume 13 has been reached. Once the pressure vessel 1 is pressurised, fluid begins to Thermosyphon through the mechanical seal 2 via the seal feed and return pipes 5 and 6 respectively.

Referring to Fig. 2 of the accompanying drawings, there is shown the system of invention in an alternative operating state such that normally open solenoid fill valve 11 is closed and normally closed solenoid drain valve 14 is open such that the fill volume 13 is emptied from pressure vessel 1. In conjunction with normally open solenoid fill valve 11 being closed, three way solenoid valve 15 switches so as to change the connection of seal return pipe 6 from running to the pressure vessel 1 via return port 4 to direct feed line 16, thus diverting the fluid from supply port 7 directly to the mechanical seal 2 via the non-return valve 8, pressure regulator 9 and pressure gauge 12.

Once fluid enters the mechanical seal 2 via return pipe 6, it is passed back into the vessel via feed pipe 5 and through feed port 3 and onto drain via normally closed solenoid drain valve 14.

In this method of operation, the system of invention is capable of dispensing cleaning fluid to the internal space of the system via normally closed solenoid CIP valve 17, which is in turn drained through normally closed solenoid drain valve 14.

Referring to Fig. 3 of the accompanying drawings, there is shown the system of invention in an alternative operating state such that normally closed solenoid drain valve 14 and normally closed solenoid CIP valve 17 are in the closed position and where fluid supplied through fluid inlet port 7 is passed into pressure vessel 1 via mechanical seal 2.

As rising fluid level 18 approached final fill volume 13, the pressure in pressure vessel 1 increases. Once the pressure is at the desired set point, pressure switch 19 activates and signals all solenoid valves back to their initial state.

Claims

CLAIMS1. A seal support system for use in conjunction with a mechanical seal installed on a piece of rotating equipment and which comprises a pressure vessel, one or more fluid inlets and connecting pipe work between the fluid inlet/s and the mechanical seal, such that it encompasses the pressure vessel and such equipment as to allow the fluid flow through the system to be altered.

A seal support system according to Claim 1, wherein the flow of fluid from one or more of the fluid inlets may be directed independently to one or more sections of the system.

A seal support system according to Claim 2, wherein the flow of fluid from one or more of the fluid inlets flows, whether directly or indirectly, to and passes through the mechanical seal.

A seal support system according to Claim 3, wherein there is provided such elements as to allow the method by which fluid is supplied to the mechanical seal to be altered as appropriate.

A seal support system according to Claim 2, wherein there are multiple methods of operation defined as primary, secondary, and, but not limited to, tertiary.

A seal support system according to all proceeding claims, wherein one of the methods of operation allows for specific aspects of the system to be made redundant to the continued operation of said rotational equipment.

A seal support system according to Claim 7, wherein one of the methods of operation allows for the replacement of the pressure vessel whilst allowing for the continued operation of said rotational equipment. 2. 3. 6. 7.

A seal support system according to Claim 5, wherein there is included, but not limited to, a primary and secondary method of operation which may be characterised in the primary case by a thermosyphon system and in the secondary case by a flush to drain system.

9. A seal support system according to Claim 1 and 3, wherein such elements that are provided for the purpose of alternating between primary and secondary operation are defined as being capable of being controlled through non-manual means.

10. A seal support system according to Claim 9, wherein there is included such controls as to allow the systems operation method to be modified manually in addition to any automation or external controls that may exist.

A seal support system according to all preceding claims, wherein there is included in the system a means by which the pressure may be determined and where such information may be used to inform control mechanisms.

12. A seal support system according to Claim 1, wherein there is provided as part of the system such elements as to allow for cleaning procedures to be carried out.

13. A seal support system according to claim 12, wherein the clean-inplace elements include a spray ball for the purposes of distributing cleaning fluid throughout the internal surfaces of the system.

14. A seal support system according to all proceeding claims, wherein there is provided such methods that allow pressure to be controlled or maintained in specific elements of the system.

15. A seal support system according to all Claim 14, wherein there is provided one or more devices that allow pressure to be maintained across the mechanical seal during methods of operation which might result in there being a change in pressure.

16. A seal support system according to Claim 1, wherein there is provided a method to drain excess fluid from the system.

17. A seal support system according to Claim 1, wherein there is provided a means of negating pressure build up when required.

18. A seal support system according to all preceding claims and as characterised herein.

19. A method of operating a seal support system for use in conjunction with a mechanical seal installed on a piece of rotating equipment and which comprises a pressure vessel, one or more fluid inlets and connecting pipe work between the fluid inlet/s and the mechanical seal, the method comprising altering the fluid flow through the system whereby a part of the system is isolated.