GB2207911A

GB2207911A - Device for inhibiting corrosion in a pipe

Info

Publication number: GB2207911A
Application number: GB08718788A
Authority: GB
Inventors: Noel Frederick Brittain
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-08-07
Filing date: 1987-08-07
Publication date: 1989-02-15
Also published as: GB8718788D0

Abstract

A device for inhibiting corrosion in a pipe comprises a container (4) for a corrosion inhibiting substance, means such as a tube for conveying the corrosion inhibiting substance to a liquid such as condensed steam which is to flow through the pipe, and means such as a venturi nozzle for dosing a predetermined amount of the substance into the liquid in dependence on the rate of flow of the liquid. The container may be in the form of a replaceable cartridge. The flow rate may be determined by the operations of a steam trap 2 which accounts a predetermined amount of condensed liquid before passing the liquid to the pipe through a non-return valve 3. <IMAGE>

Description

DEVICE FOR INHIBITING CORROSION IN PIPES The present invention relates to a device for inhibiting corrosion in pipes, for example in steam condensate pipes.

In installations where steam is used, corrosion can occur when the steam is condensed to water. Corrosion is conventionally inhibited by introducing suitable chemicals into the feed water to the boiler which generates the steam. However, tllere are some installations where live steaL is used, for example in hospitals for cooking and steriiising and in food processing factories, and in which it is not peri:issi#fe to introduce such chericals into the boiler feed water.The consequential corrosion can require frequent replacement of the pipework which can be expensive both in terns of materials and in respect of the tiele during which the stearyl is not available.

It is an object of the present invention to provide a device for inhibiting corrosion in pipes in such situations where it is not possible to introduce suitable chemicals into the boiler feed water.

According to the present invention there is provided a device for inhibiting corrosion in a pipe, the device comprising: a container for a corrosion inhibiting substance; means for conveying the corrosion inhibiting substance to a liquid which is to flow through the pipe; and means for dosing a predetermined amount of the substance into the liquid in dependence on the rate of flow of the liquid.

The container nay be in the form of a cartridge which is replaceable. The cartridge may be refilled for repeated use.

The means for conveying the corrosion inhibiting substance to the liquid may comprise a tube or, alternatively, nay comprise an injection system.

The dosing means may comprise a venturi from which is drawn a predetermined amount of the substance depending on the flow rate of the liquid. The flow rate nay be determined by the operation of a steam trap which accumulates a predetermined amount of liquid before passing the liquid to the pipe. Electronic or ultrasonic means may be used to detect the operation of the steam trap if desired.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be riade, by way of exarple, to the accompanying drawings in which: Figure 1 is a diagralatic illustration of one embodiment of the present invention Figure 2 is a @iagrammatic elevational view of an upper portion of a cartridge container; Figure 3 is a plan view of the upper portion of the cartridge container; Figure 4 is a diagrammatic elevational view of a losJer portion oi the cartridge container; Figure 5 is a plan view of the lower portion of the cartridge container; and Figure 6 is an elevational view on a different scale of a cartridge to be arranged in the cartridge container illustrated in Figures 2 to 5.

Figure 1 shows a part of a steam condensate pipe which includes a strainer 1, a steam trap 2, a non-return valve 3, and a cartridge container 4. The strainer 1 filters out any unwanted particulate matter in the condensate, while the steam trap 2 accumulates condensate in a known manner up to a predetermined amount and then opens to pass the accumulated condensate and begins once again to accumulate more condensate. The non-return valve 3 prevents condensate flowing in the wrong direction through the condensate pipework.

Figures 2 to 5 show the cartridge container 4 in more detail. The cartridge container comprises an upper portion 5 anci a lower portion 6. The upper portion has a bore 7 formed therethrough having an inlet 8 and an outlet 9 for condensate and a bore 10 formed at right angles to the bore 7 and cornitiunicating between the bore 7 and the lower portion 6. Four holes 11 are forned for bolting the upper portion 5 to the lower portion 6. The lower portion 6 is cup-shaped to receive a cartridge which will be described in more detail hereinafter and is also provided with four holes 12 for receiving bolts (not shown).

Figure 6 shows a cartridge 13 which contains a corrosion inhibiting substance and which, in use, is disposed within the lower portion 6 of the cartridge container 4. The cartridge 13 comprises an outer cylindrical wall 14 with lower and upper end closures 15,16 respectively.

Positioned in the upper end closure 16 is a central plug 17 which engages with the bore 10 formed in the upper portion 5. The plug has two holes 1S,19 formed therethrough, one of which holes 18 is connected to a venturi tube 2O which extends towards the bottom of the cartridge 13 and serves as a metering jet and the other of which holes 19 serves as a pressure balancing means for the cartridge.The cartridge 13 may be sealed in the bore 10 by neans of a screw thread or by any other convenient rears. The upper and lower portions may be mace of any suitable corrosion resistant material and nay, for example, be cast in Inalleable iron or @ronz@. Th e cartridge described is refillable and e spent cartridge car readily o replaced b y a re-charged cartridge by removing the four bolts, replacinr the cartridge and subsequently @e@lacing the bolts. However, other forms of cartridge can be employed and it is possible, for example, to use disposable cartridges or cartridges which are secured directly to the upper portion 5 an@ do not require a lower portion C. It is possible to detect chemically whether or not a cartridge is exhausted, but a visible means of determining the contents of the cartridge may also be provided. The cartridges may be made in a number of convenient sizes but I have found, for example, that a cartridge having a diameter of 84mm and a height of 170mm has a service life of the order of three hundred hours before it is exhausted.

In use, stea which has been used upstream of the strainer 1 condenses and flows through the strainer, through the bore 7 of the cartridge container 4 and accumulates in the steam trap 2. When a predetermined amount of condensate has accumulated the steam trap opens to pass the condensate through the non-return valve 3 and through the condensate piping. There is no risk of corrosion from the steam itself, but when the steam condenses and is able to absorb oxygen and quickly erodes steel pipes.

Ffhcn the steal trap opens to pass the condensate it causes a brief flow of liquid and gas through the bore 7. This gives rise to a veilturi effect at the hole 1 & l a Grasis an amount of the corrosion inhibiting substant~ contained in the cartridge i3 into the liquid in the bore 7. The substance can be any of a number of well known anti-corrosive agent and is therefore injected directly into the condensate at the point at which it is required.

The rate at which the substance is injected into the condensate in the illustrated embodiment is controlled by the operation of the steam trap which causes a flow of fluids. There are no moving parts to be serviced and no source of electrical power is required. Moreover, because the rate at which the corrosion inhibiting substance is injected into the condensate is controlled by the operation of the steam trap the chemcial is only used when the installation is working and using steam.The condensate is most aggressive at relatively low temperatures which arise, for example, during start up and at times of heavy demand, but each time the steam trap opens to pass condensate a metered amount of the corrosion inhibiting substance is introduced into the condensate which in due course passes trough the steam trap to protect the pipework downstream.

Although the use of the venturi elect has certain advantages, avoiding as it does the need for an external source of power, it is also possible to employ electronic or ultrasonic devices for detecting the operation of the steam trap and to erect the injection of a preueternined amount of corrosion inhibiting substance into the condensate in response to the operation oi the steam trap.

Claims

1. A device for inhibiting corrosion in a pipe, the device comprising: a container for a corrosion inhibiting substance; means for conveying the corrosion inhibiting substance to a liquid which is to flow through a pipe; and means for closing a predetermined amount of the substance into the liquid in dependence on the rate of flow of the liquid.

2. .- device as claimed in claim 1, wherein the container is in the form of a cartridge which is replaceab e.

3. A device as claimed in claim 2, wherein the cartridge can be refilled for repeated use.

4. A device as claimed in claim 1,2 or 3, wherein the means for conveying the corrosion inhibiting substance to the liquid comprises a tube.

5. A device as claimed in claim 1,2 or 3, wherein the means for conveying the corrosion inhibiting substance to the liquid comprises an injection system.

6. A device as claimed in any one of claims 1 to 5, wherein the dosing means comprises a venturi from which is drawn a predetermined amount of a substance depending on the flow rate of the liquid.

7. A device as claimed in any one of claims 1 to 6, wherein the flow rate is determined by the operation of a steam trap which accumulates a predetermined amount of liquid before passing the liquid to the pipe.

8. A device as claimed in claim 7 and including electronic or ultrasonic means for detecting the operation of the steam trap.

9. A device for inhibiting corrosion in a pipe substantially as hereinbefore described with reference to the accompanying drawings.