WO2002068109A1

WO2002068109A1 - A method for injecting an additive into a pressurized fluid system

Info

Publication number: WO2002068109A1
Application number: PCT/NO2002/000080
Authority: WO
Inventors: Sölve FJERDINGSTAD
Original assignee: Fjerdingstad Soelve
Priority date: 2001-02-27
Filing date: 2002-02-26
Publication date: 2002-09-06
Also published as: NO20011005L; NO20011005D0; NO313791B1

Abstract

An addictive such as biocides, is injected into a pressurized fluid system, such as a lubricating oil system, by filling the additive into a container (22) provided with a fluid entrance (32) and a fluid exit (35), positioning said container (22) into a pressure chamber (2) having an inlet (12) communicating with a bleed point (A) of the fluid system via an initially closed inlet valve (18), on one hand, and on the other hand, with the entrance (32) of the container (22), and having an outlet (14) which, via an initially closed outlet valve (19), is associated with a return point (B) of the pressurized fluid system (S). Upon opening of the inlet and outlet valves (18,19), the fluid is allowed to flow through the initially additive-filled container (22) and back to the pressurized fluid system (S) via the return point (B) in a predetermined time.

Description

A METHOD FOR INJECTING AN ADDITIVE INTO A PRESSURIZED FLUID

SYSTEM

The invention relates to a method for injecting an additive into a pressurized 5 fluid system.

There is a need within the industry to be able to inject an additive, such as a liquid, gas or solid, into pressurized fluid systems. An example is biocides that are added to a liquid which has been pressurized to permit treatment of a growth of undesired micro-organisms in the liquid or biofilm developed at the surface ofo pipe walls or components of the liquid-filled system.

It is often problematic to be able to perform such injection in an effective and practical manner. Thus, when dispensing a biocide (bactericide) or liquid additive, for example, in pressurized fluid systems, it is difficult to treat the system locally, and at present a normal procedure is to add the additive to the system5 tank which sometimes can be located remote from the place where treatment is needed.

Some liquids and substances are slowly miscible, so that it takes time to achieve the desired concentration of intermixed additive at the right level in all parts of the system. o One has now unexpectedly found a substantially simpler and more effective solution of the above problem, by using a device essentially similar to the "sampling assembly" as disclosed in the applicant's NO patent no. 171 430 (corresponding to EP patent, publication no. 548 187 B1), which is intended for a totally different field of application, namely for obtaining a representative fluid sample5 from a pressurized fluid system. By using the sampler as an injector, a bottle filled with the additive can be placed in the pressure chamber, whereby the liquid to be treated will bring the additive into circulation locally when the valves of the injector is opened. Thus, in this manner an area of the system to be locally treated with a higher concentration of additive, can be added in controlled dosages thereto.o A considerable number of samplers have already been installed in many different hydraulic and lubricating oil installations, in water systems and chemical plants. When analysing liquid as sampled by using such samplers, the systems have proved to be in need of treatment, which has proved to be possible by using the sampler as an injector.

This is useful in all fluid systems in which chemicals or solids are to be added under controlled conditions. Some typical applications are noted:

Hydraulic and lubricating oil systems at oil production plants, such as at steering propellers in floating installations in which microbic growth often occurs owing to a leaking propeller seawater seal;

- processing plants and paper mills in the wood-processing industry, where water and processing chemicals seeping therein might change the properties of the lubricating oil or exposing it to growth;

- dispensation of chemicals into fresh water pipes for pharmacy or hospital installations;

- injection of additives into liquids in the food industry. By using the sampler as an injector the utility value of the equipment involved is enhanced, resulting in a wider range of applications of the equipment. The invention is defined in the appending claims.

The invention is described in more detail below, with reference to the drawings, in which Fig. 1 is a plan view of a possible embodiment of an injector assembly essentially similar to the sampler assembly according to NO 171 430, Fig. 2 is a longitudinal section along line ll-ll in fig. 1 , and Fig. 3 is a section like fig. 2, but illustrating a somewhat modified embodiment. In the drawings reference numeral 1 generally denotes the above injector assembly associated with a circulating pressurized fluid system S into which an additive, such as a biocide, is to be injected. The injector assembly 1 comprises a pressure chamber 2 designed to resist a pressure at least as high as the pressure of the fluid system S. In the example shown pressure chamber 2 consists of a cylindrical lower body 4 releasably and sealingly connected to an upper body 6, e.g. by means of threads 8 and sealing ring 10. The upper body 6 is provided with an inlet 12 and outlet 14 each connected to a respective coupling member 16a, preferably of the rapid coupling type. Further, the inlet 12 and outlet 14 each communicates with a manually activated flow control valve 18 and 19 respectively. A closable vent 20 is provided at the top of the chamber 2 upper body 6 and a closable drain 21 is provided in the bottom of the chamber lower body 4.

The pressure chamber 2 is constructed to house an additive container 22, e.g. in the form of a glass bottle having a removable cap 24, e.g. made from hard plastics. The bottle 22 rests on a support 26 in the chamber lower body 4, and a top portion 28 of the cap 24, including a seal ring 30, is sealingly received in an annular recess in a reduced diameter portion 27 of the chamber upper body 6. The bottle cap 24 is provided with a substantially horizontal entrance 32 one side of which communicates, via a passage 33 through the reduced diameter portion 27 of the pressure chamber upper body 6, with the pressure chamber inlet 12, and the other side of which communicates with a dip tube 34 depending towards the bottom of the bottle 22. A vertical passage 35 through the bottle cap 24 forms an exit from the bottle 22. Optionally, a spring-biased normally closed bypass valve 40 may be installed in the pressure chamber 2 connected to the inlet 12 in the chamber upper body 6.

The above described injector assembly 1 operates essentially in the following manner. The container 22 is at least partly filled with the injection additive and placed in the injector assembly 1. With closed inlet and outlet valves 18, 19 and closed vent and drain openings 20, 21 the two coupling members 16a of the injector assembly 1 are connected to mating coupling members 16b provided at a bleed point A and a return point B respectively in the pressure fluid system S. The inlet valve 18 is gradually opened while vent 20 is also opened. Fluid from the system S to be treated then flows via bleed point A and inlet 12 into the pressure chamber 2 filling the latter, including the injector bottle 22, as the air present in the chamber evacuates through vent 20. Once all of the air is evacuated vent 20 is closed. When the outlet valve 19 is now opened, fluid from the system S will flow through the injector assembly 1 as indicated by arrows in fig. 2: from the pressure chamber inlet 12 along the passage 33 in chamber upper body 6, into the entrance 32 of the bottle cap 24 and down through the dip tube 34 to the bottom of bottle 22, out of the bottle through exit passage 35 in the bottle cap, and out through chamber outlet 14 back to the pressurized fluid system S through return point B. When flowing through the partly or wholly additive-filled container 22, the fluid will gradually entrain the additive into the fluid system S and disperse the additive progressively or uniformly into the fluid system as the flow continues. The valves 5 18, 19 are of the type in which the flow rate of the fluid continuously flowing through the injector assembly can be adjusted from zero (closed valve) to a predetermined maximum value, by appropriate setting of either one of these valves, preferably the outlet valve 19.

The injector assembly 1 may be connected in series with the flow circuit ofo the fluid system S, i.e. the entire circulation fluid flow passes through the injector; or it may be connected in parallel such that only a partial flow passes through the injector. The bypass valve 40 is important, particularly in the first mentioned series coupling alternative, if the cross section or capacity of the injector bottle 22 is insufficient to cope with the entire fluid flow through the chamber inlet 12, sinces it permits part of the main fluid flow to pass through the injector and back into the system. Thus, in this case a sample is taken of a partial flow depending on the biasing force of the bypass valve spring.

The fluid is allowed to circulate for at least 15 to 20 minutes to make certain that the additive in the injector bottle 22 is completely injected and intermixed witho the pressure fluid, whereupon the outlet valve 19 is closed to stop the above described fluid circulation. Then also the inlet valve 18 is closed.

The pressure in the injector 1 is then released by opening the vent 20. Then drain 21 is opened to empty the fluid present in the pressure chamber, leaving the fluid in the injector bottle 22 below its entrance 32. 5 Now the lower body 4 of the pressure chamber 2 can be unscrewed from the upper body 6 and the injector bottle 22 lifted out of the chamber lower body after having placed a plastics lid 38 or the like over the bottle cap top portion 28 and closed its entrance 32 by means of a plug or the like (not shown) to thereby close the bottle which may then be emptied and possibly filled with additive foro further injection. Finally injector 1 can be uncoupled from the system points A, B if desired.

If the injector 1 is to be connected in series with the fluid system S, then the modified embodiment V shown in fig. 3 might be advantageous. Here the bypass valve 40 of the embodiment according to fig. 2 is omitted and the dip tube 34 of the latter embodiment is replaced by a pitot tube 34' one leg of which is positioned directly in the fluid flow path between the inlet 12' and outlet 14' of the pressure chamber 2', the other leg thereof extending down into the injector bottle 22' through a vertical entrance in the bottle cap 24'. As for the rest the design and operation of the injector V is essentially similar to that of the preceding injector according to figs. 1 and 2.

Although the injector in the above example is adapted to be removably connected to the fluid system to be treated, it may advantageously be perma- nently connected thereto, e.g. in case the fluid system is a machinery lubricating oil system. This would allow maintainence inspectors to inject the additive into the lubricating oil system of several machines during routine inspection rounds.

Of course the injector bottle 22 need not be shaped and supported exactly as described above and illustrated in the drawing, and similarly the pressure chamber 2 need not be designed in exact conformance with the given examples, since a person skilled in the art may easily recognize larger or smaller design modifications without departing from the inventive idea. The essential thing is that the injector 1 is constructed in such a way that the pressurized fluid to be treated is allowed to flow through the injector container in the pressure chamber for a predetermined time interval and the container then removed from the injector in a simple manner.

The additive need not necessarily be a fluid. It may also be a gas or a solid such as powder or in the shape of a "sugar lump" or "piece of soap" gradually dissolving during circulation of the pressure fluid through the injector. The circula- tion time will depend on the nature of the additive. With a fluid additive the circulation time will be at least 15 - 20 minutes, while for a dissolvable solid additive it will normally be longer.

Claims

C L A I M S :

1. A method for injecting an additive into a pressurized fluid system, c h a r a c t e r i z e d by filling the additive to be injected into a container (22) provided with a fluid entrance (32) and fluid exit (35); positioning said container (22) into a pressure chamber (2) having an inlet

(12) communicating, on one hand, with a bleed point (A) of the fluid system via an initially closed inlet valve (18) and, on the other hand, with the entrance (32) of the container (22), and having an outlet (14) which, via an initially closed outlet valve

(19), is associated with a return point (B) of the pressurized fluid system (S), and, upon opening of the inlet and outlet valves (18, 19); permitting the fluid to flow through the initially additive-filled container (22) and back to the pressurized fluid system (S) via the return point (B) in a predeter- mined time.

2. Method according to claim 1 , where the additive is in the form of a gas.

3. Method according to claim 1 , where the additive is in the form of a solid which is gradually dissolved during the flowing of the pressurized fluid through the additive- filled container.