GB2356242A

GB2356242A - Steam accumulator with centrifugal separators

Info

Publication number: GB2356242A
Application number: GB9923102A
Authority: GB
Inventors: David Oakland
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-01
Filing date: 1999-10-01
Publication date: 2001-05-16
Also published as: GB9923102D0

Abstract

A steam accumulator 5 is provided with centrifugal separators 4 which remove water from the steam as it is discharged. The accumulator stores surplus steam from a boiler 1 in water. When steam is required, a pressure drop is allowed to occur in the space above the water, causing steam to evaporate from the water. Any mist or water entrained in the steam is removed by the centrifugal separators, so that near dry, saturated steam is supplied to the outlet pipeline 6. The provision of the centrifugal separators means that the water surface area and therefore the size of the accumulator can be reduced.

Description

1 2356242 HIGH VELOCITY STEAMING SYSTEM (HVSS) (High velocity steam

accumulator).

This invention - the 1UGH VELOCITY STEAMING SYSTEM (HVSS) relates to a method of reducing the size of a steam accumulator by increasing the normal maximum allowable steam disengagement velocity and steam accumulator apparatus for use in carrying out the method.

The theory of steam accumulation is well known and concerns the means by which wide variations in process steam demand may be balanced to achieve a relatively steady demand on the steam source (a boiler). A steam accumulator stores surplus steam produced in the boiler at times of low demand for subsequent release to satisfy the process requirements at times of high demand.

Water is used as the storage medium in the accumulator. The water is heated in the storage vessel by the charging of surplus steam produced by the boiler. The effect is to cause a rise in the temperature and the pressure of the water until the same enthalpy conditions that exist in the incoming steam are reached.

The capacity for 'storing steam' relies on an operating pressure differential between the pressure to which the accumulator is charged and that at which steam is discharged to satisfy the temperature conditions required by the steam consumer. The stored energy (steam) is evaporated from the water by allowing a pressure drop to occur in the steam space above the water, i.e., to let steam flow out of the accumulator. The theory is known as the 'pressure-drop' principle.

The normal maximum allowable maximum disengagement velocity for steam evaporating from the water surface of a pressure drop accumulator is normally limited by the conditions required to maintain the release of dry-saturated steam. Drysaturated steam exists when its temperature corresponds to its water boiling point with no water present in the steam vapour. The 'conditions' are governed by consideration of three design parameters - being the density of the storage water, the volume of the steam space above the storage water and the surface area of the storage water. The surface area of the water is directly related to the speed of the steam as it evaporates from the surface of the storage water (termed the disengagement velocity) and is normally maximised at known values relating to operating pressure. Therefore, water surface area is an intrinsicyalue in the determination of vessel size.

The danger resulting from the use of a vessel affording insufficiently large water surface area is the release of wet steam and in the worst case the carry-over of water from the accumulator into the steam supply system.

Continued........

Z A completely new method of reducing the size of the storage vessel whilst maintaining the release of near dry-saturated steam is embodied in the new'high velocity steaming system' (HVSS) in which the normal maximum allowable steam disengagement velocity is increased. By the method, the dryness fraction of the steam is quantified as being in excess of 99%.

The method involves the fitting of two (or more) internal centrifuge separators attached to a steam collection pipe located in the steam space of the accumulator vessel and through which the steam evaporating from the contained water passes before flowing out of the accumulator. Any entrained mist or water carried over by the steam evaporating from the storage water is removed as it passes into the high velocity centrifugal flow path of the separators to be collected in the bottom of the separator chambers. Thereafter the collected water is drained through an outlet aperture in the bottom of the separator chambers and hence back into the water contained in the vessel.

For a given steam discharge rate being a design requirement of the accumulator, the method HVSS enables the volume of the accumulator to be smaller than would otherwise be possible, the vessel construction cost is by the method is reduced and being smaller, the vessel c an be more easily accommodated in the space available.

According to the invention, the method (HVSS) will comprise essential components being a storage vessel, an internal steam collection pipe, a number of centrifuge separators, and inlet and outlet pipelines.

A specific embodiment of the invention will now be described by way of example using a steam accumulator and with reference to the accompanying drawing in which:- 1. Component is a steam source (a steam Boiler).

2. Component is a means for conveying steam into the storage vessel (a pipeline).

3. Component is a steam storage vessel (steam accumulator).

4. Component is a number of centrifuge separators attached to the header (5).

5. Component is a steam collection header connected to outlet pipeline (6).

6. Component is a means for conveying steam out of the storage vessel (a pipeline).

Referring to the drawing, steam is generated in the boiler (1) and is charged by means of the inlet pipeline (2) into the steam storage vessel (3). Thereafter the stored steam is released via the centrifuge separators (4) into the collection pipe (5) before being discharged into the outlet pipeline(6).

Again referring to the drawing, any entrained mist or water carried with the steam evaporating from the storage water is removed as it passes through the centrifuge separators (4) to be collected in the bottom of the separator chambers. Thereafter the collected water is drained through an outlet aperture in the bottom of the separator chambers and hence back into the storage water.

By this method, the size of a steam accumulator vessel is reduced and the rate of discharge of dry saturated steam is maintained.

3

Claims

1. A method of reducing the volume of a steam accumulator.

2. A method according to claim I which makes use of apparatus comprising a steam storage vessel, inlet and outlet pipelines, and a configuration of internal centrifuge separators and steam collection pipe.

3. A method according to claims I and 2 wherein the normal maximum allowable steam disengagement velocity is increased.

4. A method according to claims 1, 2, and 3 wherein the flow of near drysaturated steam is maintained.

Amendments to the claims have been filed as follows 1. A method of reducing the dimensional size of a steam accumulator.

2. A method according to claim 1 which makes use of apparatus comprising a steam storage vessel, inlet and outlet pipelines, and a configuration of internal centrifuge separators and steam collection pipe.