AU658920C

AU658920C - Isokinetic sampling apparatus

Info

Publication number: AU658920C
Application number: AU23807/92A
Authority: AU
Inventors: Bjorn Dybdahl
Original assignee: Petrotech AS
Current assignee: Petrotech AS
Priority date: 1991-07-17
Filing date: 1992-06-29
Publication date: 1995-11-23
Anticipated expiration: 2012-06-29

Description

ISOKINETIC SAMPLING APPARATUS

The invention relates to an isokinetic sampling apparatus adapted to take isokinetic fluid samples under different production conditions and connectable to a sampling point in a pipe, a tank, a separator, a heat exchanger, etc. , wherein the fluid flows and is under a substantial pressure.

In order to describe the flow pattern of a fluid flow during different production conditions in accordance with the above, it is necessary to provide isokinetic fluid samples. A suitable apparatus for this purpose and connectable to any sampling point, is currently not available on the market.

Therefore, there exists a need for an isokinetic sampling apparatus of the kind defined introductorily and which, moreover, enables sampling anywhere across the cross- sectional area of the fluid flow, e.g. in the middle of the flow or in the external boundary layer (at the inner wall surface of the pipe or container wherein the fluid flows) .

This need is covered by means of an isokinetic sampling apparatus according to the invention which is designed as set forth in the following claims.

By means of the fluid sampling apparatus in accordance with the invention, one may isokinetically take samples in all connections having association to trace elements and for separator efficiency with downstream or upstream sampling, wherein the fluid at all times is in flowing movement.

The sampling apparatus according to the invention bring about sunstantial time savings and, consequently, cost savings.

The sampling apparatus according to the invention comprises a cylinder-shaped housing having (ball) valve and coupling means for fluid-tight interconnection to e.g. a socket of a container, a tank, a separator, a heat exchanger or the like through which the fluid in question flows. A pressure fluid operated piston rod consisting of two concentrical pipes cooperates with said valve means and carries at the free end thereof a preferably replaceable probe with an orifice plate. Only the inner pipe of the piston rod is in connection with the orifice plate-equipped probe, but also the outer pipe has an orifice plate at a certain distance from the orifice plate of the probe, preferably 180° angularly displaced in relation to the latter.

As soon as fluid-tight conditions have been established between said sampling point and the apparatus, the valve thereof is opened and the probe is pushed through the valve through fluid pressure within the cylindrical housing, piston and piston rod into the fluid flow for sampling. Thereby, one may position the outer orifice plate of the probe opposite to the direction of flow and take out a defined part flow, while the 180° angularly displaced orifice plate of the outer pipe of the piston rod takes out a reversed part flow.

As soon as the desired samples have been taken, the valve is closed and the probe withdrawn through piston and piston rod. Thereafter, one may possibly change the probe, actually the outer orifice plate, for new sampling. Upon variations in speed of flow of the flowing fluid, the piston may be reversed, the valve closed, the pressure relieved and the probe replaced.

An example of a possible embodiment of an isokinetic sampling apparatus according to the invention is further explained in the following, reference being made to the accompanying drawings, wherein:

Figure 1 shows the apparatus coupled to e.g. a tank, wherein a fluid flows and the flowing pattern thereof is to be determined, and wherein the probe occupies a withdrawn, inactive position of readiness;

Figure 2 shows the same arrangement as figure 1, but here the probe occupies an extended, active position, the orifice plate thereof being situated in the middle of the fluid flow;

Figure 3 shows, on a larger scale, a releasably connectable prope of the design shown in figures 1 and 2, as well as the immediately adjacent end portion of the inner and outer pipe of the piston rod, and an intermediate bayonet joint between probe and inner pipe end;

Figure 4 shows a view corresponding to figure 3 of a releasably connectable prope according to another embodiment;

Figure 5 shows the prope design of figure 4 in a plane extending perpendicularly to the drawing plane according to figure 4.

First, reference is made to figures 1 and 2.

Here, reference numeral 1 denotes a tank, a centrifuge, a heat exchanger or similar container or pipe^'wherein a fluid flows and whose flow pattern is to be determined on the basis of sampling by means of the apparatus according to the invention .

For the purpose of sampling, the tank 1 is formed with one or more sampling points in the form of one or more connection sockets 2, reference numeral 3 denoting an in per se known connector having oppositely directed conical spigot portions 4,4' and a central tightening nut 5. One end- portion 4 is screwed into the socket 2 of the tank 1, the other end portion 4 ' being screwed into an internally threaded sleeve portion of the housing of a shut off valve 6, e.g. in the form of a ball valve of a construction known per se and incorporated into the sampling apparatus according to the invention.

The connection of the ball valve 6 and, consequently, of the apparatus according to the invention to the sampling point 2 occurs with closed valve, figure 1, the connection device and the ball valve 6, which may have a manual operating handle 6', may be of conventional kinds.

The shut off valve 6,6' is screwed onto a cylinder 7 having end caps 7',7", constituting the apparatus housing.

Concentrically within the cylinder 7, a piston rod 8 is supported, passages being formed in the end caps 7 ',7" of the cylinder 7, said piston rod 8 approximately in the middle of the length thereof carrying a piston 9. The cylinder 7 and the end caps 7',7" may be honed internally.

The circumferential surface of the piston 9 is sealed against the inner mantle surface of the cylinder 7 by means of O-rings and seal rings. Preferably, the stroke of the piston 9 is variable.

According to the embodiment shown, the piston rod 8 consists of two concentrical pipes, an inner pipe 8 ' ^* and an outer pipe 8". As it appears from figure 3, the outer pipe has a radially inwardly directed ring flange 10 through which the adjacent outer end portion of the inner piston rod pipe 8' extends,' the connection therebetween being fluid-tight.

The preferably variable stroke of the piston 9 is in any case such that the active (left) end of the piston rod 8, in the withdrawn position of figure 1, is situated upstream closed ball valve 6 and such that said end (which carries a probe later to be described) , in the extended position of figure 2, is situated downstream open ball valve 6 and enables "surveillance" of the flowing fluid across the diametral extent of the flow area thereof.

In accordance with the embodiment shown, releasably connectable probes 11, figure 3, and 12, figures 4 and 5, have been used, which gives the advantage that various orifice plates may be used, each provided in a separate probe body.

Each probe 11 and 12, respectively, may be anchored releasably to the free end portion of the inner pipe 8 • of the piston rod 8 in any suitable manner; in figures 3 - 5 a bayonet joint 13 has been indicated.

Each probe 11 and 12, respectively, is formed with at least one outer opening 14 connected to a channel 14 ' communicating with the bore of the inner piston rod pipe 8¹. In the following, said opening with its associated channel will be designated an orifice plate.

The orifice plate in the probe design 11 will be capable of being used in fluid sampling in the middle of the cross section of a flowing fluid, as well as adjacent the inner wall of the tank 1.

The orifice plate 14 in the probe design 12 according to figures 4 and 5 is, moreover, capable of taking fluid samples isokinetically close adjacent said tank inner wall. This is due to the fact that the extreme orifice plate edge or mouth edge 14" coincides with the extreme point of the probe point. Thus, one may "scrape off" fluid samples from the tank inner wall by means of this probe point/orifice plate design.

Likewise, the outer pipe 8" of the piston rod 8 has an orifice plate 15, see figures 3 - 5, which is oriented with an 180 degrees angular displacement in relation to the orifice plate 14 of the probe 11 and 12, respectively. The orifice plate 15 of the outer piston rod pipe 8" may e.g. be 5 mm.

At the opposite end of the probe 11 and 12, respectively, the inner piston rod pipe 8^• is mounted to a valve through a T-connector 16.

The annulus between the inner and outer piston rod pipes 8', 8" communicates with a pipe 17, wherein a valve is mounted.

In the end cap 7", an intake for the connection to a hydraulic pump has been mounted, adapted to effect a controlled displacement movement of the piston 9 and, consequently, of the piston rod 8 toward/through/away from the ball valve 6.

The reference numeral 18 denotes a valve for the relief of pressure or hydraulic return pumping of the piston 9 with the piston rod 8 and the probe 11 or 12, respectively. Maximum pressure is equal to e.g. 1500 bar.

As soon as the isokinetic sampling apparatus according to the invention is coupled to a samling point 2 as shown in figure 1, the ball valve 6 is opened and the probe 11 or 12, respectively, is through the piston 9 and the piston rod 8 pushed into the fluid flow within the tank 1, in that the pushing-in or penetration depth for the probe 11 or 12, respectively, is chosen according to desire and need. Thereby, the orifice plate 14 of the probe 11 or 12, respectively, is positioned such that it faces opposite the direction of flow, whereby a fluid sample is taken out in the form of a defined part stream through the inner pipe 8 ' (at 16) . Thereby, the orifice plate 15 of the outer pipe 8" will be oriented with a 180 degrees angular displacement in relation to the orifice plate 14, and through the orifice plate 15 one may, thus, take out a reversed part stream.

Upon changes in the fluid's speed of flow, the piston 9 may be reversed when pumping hydraulic oil through the valve 18; further closing the valve 6, bleeding off pressure and removing the probe 11 or 12, respectively, and mounting a new probe, opening the valve 6 and pushing the probe 11. or 12, respectively, in again to desired penetration depth within the tank 1.

Claims

C l a i m s

1. An apparatus for isokinetic sampling of fluid flowing under high pressure in a tank (1) , a separator, a heat exchanger or other container/pipe assigned at least one samling point (2), c h a r a c t e r i z e d i n that the isokinetic sampling apparatus comprises a pressure fluid-operated cylinder (7,8,9), which is connected or connectable, respectively, to a shut off valve (6,6'), which is connectable to said sampling point (2) and which in an open condition allows passage of the cylinder's (7,8,9) piston rod (8) , which is tubular and whose free end carries or is formed for interconnection with, respectively, a probe (11;12) , which is adapted to be displaced into the fluid flow and whose displaceable portion is provided with at least one orifice plate (14) which is in fluid communication with the bore of the piston rod (8').

2. An apparatus according to claim 1, c h a r a c t e r i z e d i n that the piston rod (8) consists of two concentrical pipes (8',8"), of which the innermost (8') carries the orifice plate probe (11;12) or is connectable thereto, respectively, the outermost pipe (8") of the piston rod (8) being formed with at least one orifice plate (15) .

3. An apparatus according to claim 2, c h a r a c t e r i z e d i n that the two orifice plates (14,15) are 180 degrees angularly displaced in relation to each other, so that one through orienting the probe (11;12) with its orifice plate (14) facing opposite the flowing direction of the fluid may take out a fluid sample in the form of a defined part flow through the inner piston rod pipe (8'), while one by means of the outer piston rod pipe's (8") orifice plate (15) may take out a fluid sample in the form of a reversed part flow.

4. An apparatus according to claim 1, 2 or 3, c h a r a c t e r i z e d i n that the outermost mouth edge (14") of ther orifice plate (14) of the probe (12) extends itself beyond or coincides with, respectively, the extreme point of the probe point.