GB2152868A - Analytical unit - Google Patents

Abstract

An analytical unit of modular structure comprises interconnecting upper and lower sections. The upper section 1 comprises a working area containing glove ports 4, a sample port 4, a first liquid entry port 6 for water, a second liquid entry port 8 for neutralizing solution and a sink 5. The lower section 2 contains a fan 10 for withdrawing fumes from the upper section to the lower, an outlet 20 for the sink, a compartment 23 for the neutralizing solution, a compartment 25 for a solid neutralizing agent, an outlet for liquid waste, an outlet for the neutralizing solution and a pump 26 for circulating the neutralizing solution from the lower section to the upper. The unit is particularly suitable for use in palynological investigations where laboratory facilities are limited. <IMAGE>

Description

SPECIFICATION Analytical unit This invention relates to an analytical unit and in particular to a cabinet suitable for use in palynological investigations.

Palynology is the study of acid resistant microfossils, which include spores, pollen and dinoflagellates. These have an almost indestructible covering favouring geological preservation and in many rocks are the only fossils which can be used for stratigraphical correlation.

Rapid stratigraphical knowledge is particularly important when drilling exploration or production oil wells which it is hoped or expected will strike oil in a particular stratum.

During drilling operations, drilling mud is continuously circulated to remove the cuttings from the well bore. These cuttings usually contain microfossils which may be used to characterise the stratum from which they were derived. Thus by continuously checking on the microfossils, a record can be kept of the strata through which the rock bit drills and hence of progress towards and arrival at the target.

Palynological investigations take the form of treating the rock samples with hydrofluoric acid to dissolve all extraneous mineral matter and release the organic walled microfossils. These are then studied under a microscope and the forms and distribution of the major groups enable the stratum from which they were obtained to be determined.

Drilling operations are expensive and palynological analyses must be rapid if drilling is not to be delayed unduly and extra costs incured.

Hydrofluoric acid is a hazardous chemical and special precautions must be taken when it is used.

This presents few problems for purpose built laboratories on land where space and the required facilities are readily available. Offshore, however, drilling costs and the need for rapid analyses are even greater but space and facilities are much more limited.

It is an object of the present invention to provide a compact, self-contained analytical unit for obtaining palynological specimens, suitable for use in areas where full laboratory facilities are not available, such as offshore locations.

Thus according to the present invention there is provided an analytical unit of modular structure comprising interconnecting upper and lower sections, the upper section comprising a working area containing glove ports, a sample port, a first liquid entry port for water, a second liquid entry port for neutralizing solution and a sink, the lower section containing a fan for withdrawing fumes from the upper section to the lower, an outlet for the sink, a compartment for the neutralizing solution, a compartment for a solid neutralizing agent, an outlet for liquid waste, an outlet for the neutralizing solution and a pump for circulating the neutralizing solution from the lower section to the upper.

The lower section preferably comprises a gas dispersal system for dispersing fumes pumped from the upper section into the liquid neutralising solution.

Preferably a filter, most preferably an activated carbon filter, is provided in the lower section to filter the fumes prior to dispersal.

Suitable liquid and solid neutralizing media include sodium hydroxide solution and marble chips respectively.

Suitable construction materials for the unit include polyvinyl chloride, polytetrafluoroethylene and polyesters, preferably the first of these.

The invention is illustrated with reference to Figures 1 and 2 of the accompanying drawings which are front and side elevations respectively of a cabinet.

The cabinet is free standing. It consists of an upper glove port chamber (1) and a lower neutralization chamber (2). Adjacent to the neutralization chamber are waste and dosage tanks (3) and 3A.

The face of the glove port chamber (1) is totally clear and has a 45" incline so that the operator has a large viewing area.

There are two standard laboratory glove ports (4) made from grey PVC.

The sink (5) is 200mm deep with a sloping floor to allow quick drainage. A single water inlet (6) is positioned over the sink and operated by an external kick valve (7). This valve is controlled by movement of an adjustable arm. The position of the arm can be changed so that the valve can be operated by the operators knee, (high position), or foot, (low position). Mounted in the sink is a spray bar (8) which delivers liquid from the neutralization chamber. Cold water is supplied to the cabinet, via the kick valve, by a length of PVC tubing.

A conical hood (9) is situated on the back wall of the glove port chamber. Air and gases are drawn from the glove port chamber into the neutralization chamber by a centrifugal fan (10) housed within the fan chamber. Air is recirculated via an extract (11) and return (12) duct.

There are pressure changes in the glove port chamber due to gas volume changes. The pressure in the glove port chamber is indicated by the fluid level of a manometer (13) fixed onto the frame of the cabinet in front of the sample exchange port.

The sample exchange port (14) made from PVC, is situated on the right hand side of the glove port chamber. The port has two hinged doors, one operated externally, the other internally. Both doors are fastened by quick release/metal toggles which are replaceable.

The electrical control (15) box is situated behind the sample exchange port. The box contains replaceable fuses for the fan, pumps and air circulation failure switch light.

On the left hand side of the cabinet is a Drager (16) connection valve. By using a Drager gas detector kit, acid vapour concentration inside the glove port chamber can be directly measured. The manometer connection is also located on this valve.

Spent acids react with the neutralizing agents (sodium hydroxide and calcium carbonate) in the neutralization chamber. The reactions create products which can be discharged. The neutralization chamber can be separated from the glove port chamber by the removal of bolts on the frame around the cabinet.

Access to the neutralization chamber is normally gained via an access panel (17) located on the face of the cabinet below the sink. This panel is secured by quick release toggles. Access is gained via the access panel to the sediment trap, delivery tube, dispersal foot, marble chip container and the fan chamber drain valve.

The sediment trap (18) is located below the sink.

This is a small bulb which can be detached to remove the accumulated sediment and rock fragments. A PVC delivery tube (19) leading from the sediment trap carried liquid down to the dispersal foot (20). The dispersal foot is a length of PVC tube which has small holes along its length. These allow liquid to be evenly distributed at the bottom of the neutralization chamber.

Gases and vapours from the glove port chamber are drawn by the fan through an activated carbon filter (21) and into a scrubbing system. The activated carbon filter is located on the right hand side of the cabinet. It is housed within the extract duct and therefore all gases and vapours, from the glove port chamber, pass through this filter. The filter is fastened into position by wing nuts, a gas tight seal being provided by a special gasket around the filter. A handle on the filter allows it to be withdrawn from the ducting.

After passing through the activated carbon filter, gases and vapours are ducted to the scrubbing shoe (22) located in the neutralization chamber.

The scrubbing shoe consists of lateral extension to the fan duct, which has perforations on the upper surface. Liquid in the neutralization chamber covers the upper surface of the shoe. When the fan is running, gases and vapours are vented out of the perforations and dissolve in the neutralizing solution.

The neutralization chamber is divided into two compartments. The main compartment (23) is where acid treatment and neutralization occurs.

Sodium hydroxide solution is pumped to the bottom of this compartment from an external dosage tank. Separating the compartments is a weir made from PVC. This retains liquid in the main compartment so that the scrubbing foot is kept covered by neutralizing solution. Liquid from the main compartment overflows into the subsidiary compartment. The subsidiary compartment consists of a marble chip tray (25), a recirculation pump (26) and an outlet leading to the waste tank.

Marble chips act as a neutralizing agent and filter liquid flowing into the subsidiary compartment has been neutralized. Part of this may be pumped up to the sink by the recirculation pump housed under the marble chip tray.

A length of PVC tubing, leading from the bottom of the subsidiary compartment runs around the back of the cabinet and into the waste tank (3). The end of the tube is fitted with a piece of hard PVC on a slide which can be vertically adjusted.

The waste tank has high and low liquid level switches. When set to automatic the discharge pump will automatically pump neutralized fluid to waste.

A dosage tank (3) is located adjacent to the waste tank. Sodium hydroxide solution can be pumped into the neutralization chamber by depressing the dose switch located on the control box.

The neutralization chamber can be drained by a PVC drain valve located at the back of the chamber.

Around the cabinet is a one inch metal frame.

Sheets of protective material can be fixed onto this metal frame to protect the cabinet during transportation. Extendable stabilizing feet (27) with castors, are fitted to the base of the frame. The underside of the cabinet is protected by a sheet of mild steel.

In use, a sample of rock containing microfossils is placed in a flask. The flask is inserted into the glove port chamber (1) of the cabinet through the sample exchange port (14). The glove box contains a supply of hydrofluoric acid and this is poured into the flask by manipulation through the glove ports (4). The fan (10) is switched on to remove fumes from the glove port chamber (1) and these are passed through the filter (21) and scrubbing shoe (22) and absorbed in the sodium hydroxide solution in the chamber (2).

After the rock has been dissolved, the solution in the flask containing excess acid is neutralized and the contents of the flask drained, filtered and washed. Liquids are removed through the sediment trap (18) into the chamber (2).

The microfossil residue is then removed from the glove port chamber (1) for microscopic inspection.

Claims (4)

1. An analytical unit of modular structure comprising interconnecting upper and Lower sections, the upper section comprising a working area containing glove ports, a sample port, a first liquid entry port for water, a second liquid entry port for neutralizing solution and a sink, the lower section containing a fan for withdrawing fumes from the upper section to the lower, an oulet for the sink, a compartment for the neutralizing solution, a compartment for a solid neutralizing agent, an outlet for liquid waste, an outlet for the neutralizing solution and a pump for circulating the neutralizing solution from the lower section to the upper.

2. An analytical unit according to claim 1 wherein the lower section comprises a gas dispersal system for dispersing fumes pumped from the upper section into the liquid neutralizing solution.

3. An analytical unit according to claim 2 wherein a filter is provided in the lower section.

4. An analytical unit as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.