GB2330780A

GB2330780A - Sensor and control means for oil recovery apparatus

Info

Publication number: GB2330780A
Application number: GB9723324A
Authority: GB
Inventors: Frank Mohn
Original assignee: Frank Mohn Flatoy AS
Current assignee: Framo Flatoy AS
Priority date: 1997-11-04
Filing date: 1997-11-04
Publication date: 1999-05-05
Anticipated expiration: 2017-11-04
Also published as: JPH11169847A; NO981838D0; NO981838L; GB9723324D0; GB2330780B

Abstract

An apparatus for the recovery of oil floating on the surface of water floats just below the surface of the water, skims the oil from the surface, pumps it to a recovery vessel for storage and processing and constantly measures and transmits data on its operating characteristics to a control and communication unit 45. Sensors 41, 42, 43, 44 are mounted on various positions of the apparatus to monitor continuously one or more characteristics of the system, e.g. the hydraulic pressure drop across pump 12, the pump outlet pressure, the pump-liquid temperature, the oil-water level and the oil layer thickness. The data from the sensors is processed by microprocessor means (50) located in waterproof communication unit 45 or it may be remotely sited, e.g. in an on-shore control centre (see Fig 3, not shown), and control signals are generated from unit 45 to control operating parameters such as the floatation level of the weir skirt 23 and/or the speed of pump 12. The apparatus comprises float 21, flexible skirt 23 supported around its periphery by floats 25, pump 12 with funnel shaped inlet 17, 18 and pump outlet 6 for transport of recovered liquid to a delivery vessel.

Description

APPARATUS DESCRIPTION The present invention relates to apparatus for oil recovery particularly for recovery of oil floating on the surface of water.

Oil is a serious and major polutant and can cause damage to wildlife and to the environment if it is allowed to float on waterways or on the open sea. It is also unsightly and poses a fire risk. Oil is an expensive commodity and any waste by leakage also increases the cost of production unless it can be cost effectively recovered and re-used. Hence there is a real need for an efficient apparatus to recover oil floating on water whether resulting from leakage or otherwise.

Apparatus which can accomplish such a task is known from NO 162 301 and NO 162 734 which are commonly owned.

These documents describe an apparatus which floats just below the surface of the water and skims the oil from the surface pumping it to a recovery vessel for storage and processing. The apparatus comprises a float attached to a pump, the outlet pipe of which is connected to the recovery vessel. The pump has an inlet in the form of a funnel which is connected to a flexible skirt supported by a peripheral stiffening element and floats so that it fans out over a relatively large area of the water surface to form a weir to collect the oil. The skirt is adjustable in its position relative to the funnel and, independently, in its position relative to the water surface.

The present invention relates to an improvement in an apparatus of this sort.

According to the present invention there is provided an oil recovery apparatus comprising: a buoyancy element for floating on water, supporting a pump an outlet conduit for connection and delivery of oil to a recovery vessel, an inlet funnel for the pump, an adjustable weir skirt supported by a plurality of floats spaced about its circumference, characterised by a plurality of sensors mounted on the recovery apparatus, microprocessor means connected to receive data from the sensors, and to generate at least one control signal as a function of the data, control means operable in dependence upon said at least one control signal to control the level of floatation of the weir skirt, and optionally, the speed of operation of the pump.

Hence the apparatus of the present invention incorporates automatic controls to tune the functioning of the apparatus. The data from one or more sensors, either directly or via the microprocessor means, may be transmitted to a control operator who can then fine tune the control signals to further increase the efficiency of the oil recovery procedure and may for example incorporate factors into the control signals to compensate for adverse weather or environmental conditions.

According to a preferred embodiment of the present invention the apparatus additionally comprises sensors for measuring fluid flow rates, either at the pump or in the pump outlet conduit. Further, or alternatively, sensors may be positioned to measure any or all of the following variables: -the hydraulic pressure drop across the pump -the outlet pressure from the pump -the pump liquid temperature -the level of the oil/ water mix -the thickness of the oil layer on the surface of the water.

Such sensors will usually be arranged to provide analogue signals though digital sensors could be used. The signal from the or each sensor then passses to the microprocessor means which could conveniently be a multiplex computer card which could be built into an instrument container (preferably waterproof) on the recovery apparatus.

The microprocessor means may instead be mounted on the recovery vessel, or elsewhere remote from the oil recovery apparatus itself, and the signals from the sensors, together with any control signals coming back from the microprocessor would then be communicated either through a fixed link, eg by cable, or by a remote link such as infra-red, radio or by satellite to an onshore control centre.

The data from the sensors can also be stored and used for data reporting for example to make calculations and provide statistics regarding the amounts of water and oil recovered. This information can be stored long term by a control centre and compared with subsequent data. Over time such information can be used to fine tune the algorithms and computer programs to make the apparatus more efficient in given conditions.

The control signals generated as a result of the data measured by the sensors are primarily used to control the weir skirt level, by controlling the height of the top of the skirt from the floats, and thus control the rate of input of oil and water and, depending on the depth of oil on the water (and to a certain extent the chopiness of the water surface). However, in advantageous embodiments the control signals are used additionally to control the pump speed so as to control the output rate of the oil and water. The control signals may also be used to effect control of the emulsion breaker injection: either to control the individual doses administered or the timing of the doses or both.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings, in which: Figure 1 is a cross-sectional side view of an oil recovery apparatus according to the present invention.

Figure 2 is a top plan view of the oil recovery apparatus of figure 1.

Figure 3 is a block diagram illustrating the sensing and control functions of the apparatus of figure 1.

The oil recovery apparatus illustrated, is supported in the water 1 by a main buoyancy element 21. The main buoyancy element 21 is rigidly connected to a submerged support cradle 4 in which is mounted a pump 12 with a pump motor 13.

The pump has an inlet 18 fed by a funnel 17, and an outlet 6. The outlet 6 is connected to a delivery hose or conduit 11 (figure 2) which carries the pumped oil and water to a delivery vessel (not shown) and is protected by an outer sheath 10.

The pump inlet funnel 17 tapers towards the inlet 18 from an upper flexible skirt 23 which is supported in the water 1 by floats 25 arranged at spaced intervals around its upper circumference 30. These floats 25 are connected by stiffening elements or rods 24 and keep the upper circumference 30 of the skirt open in a generally circular shape so as to provide a maximum orifice for ingress of oil and water to the funnel and thus into the pump. The upper circumference 30 lies just below the surface 31 of the water 1 and preferably just below the oil layer 32 floating on the water surface. The level of the top of the skirt is adjustable not only relative to the water surface (sea level) but also relative to the funnel 17, generally independently of the main buoyancy element 21. The skirt 23 thus acts as an adjustable weir for oil and water from the surface of the sea. The floats 25 can also be adjusted to alter the open area of the skirt. Control can be automatic and/ or in response to manual intervention.

Sensors are located on the apparatus. An oil thickness measuring sensor 41 is located at one side relatively close to the oil layer 32 and with a clear view of it. A pressure sensor 42 is located on the pump 12 to measure the hydraulic pressure drop across the pump. A temperature sensor 43 measures the temperature of the pump liquid. The proportion of oil in the water-oil mixture is measured by another sensor 44. The outlet pressure of the pump and also the output flow rate may also be measured by further sensors 45 and 46 respectively, which are shown only in figure 3.

The analogue data from these sensors is fed to an instrumentation and communication unit 45 via data communication lines which are shown in bold broken lines.

This unit 45 contains a multiplex card together with data receiving, data transmitting and communication hardware and software. The unit 45 is waterproof so as to protect the electronics contained within.

The multiplex card converts analogue signals from the sensors into serial output signals for data handling and transmission. The data is processed by a data processing unit 50, for example a microprocessor, which may be incorporated into the instrumentation unit 45 on the oil recovery apparatus, or alternatively may be sited remote from the oil recovery apparatus, for example on the vessel or in an on-shore control room. Control signals are generated as a result of calculations made on the data to control various parts of the apparatus. For example the control signals may be fed back to the multiplex card and be converted into analogue output signals for controlling the pump and the weir level via hydraulic solenoid valves.

The monitoring and control system is shown more clearly in figure 3.

Data from the hydraulic pressue sensor on the pump 12, and from the temperature sensor 43, the pressure sensor 42, the oil/ water sensor 44 and the flowmeter 46, as well as from the oil thickness monitor 41, is fed to the instrumentation and communication unit 45. This digitally converted data is then fed to the data processing unit 50 (which may also be located on the oil recovery apparatus, or may be remote therefrom on a vessel or control centre). The data is also fed to a main control centre by satellite link 51. In particular the data from the flow meter 46 and the oil/ water sensor 44 is continuously processed to calculate the the amount of recovered water and recovered oil at any moment in time.

The processed data results in control signals which are fed back to the instrumentation unit 45 and are diverted to relevant control units such as the pump speed adjustment unit 53 and the weir level adjustment 54.

Apparatus constructed according to the present invention can produce many advantages over known apparatus.

For example considerable improvements to the efficiency of the oil recovery operation are achieved, together with an operational simplification of the operation. In addition it enables automatic and continuous data recording not only on the recovery vessel but also in an onshore control room.

Thus the instantaneous amount of recovered oil can be known.

Claims

CLAIMS: 1. An oil recovery apparatus comprising: a buoyancy element for floating on water, supporting a pump an outlet conduit for connection and delivery of oil to a recovery vessel, an inlet funnel for the pump, an adjustable weir skirt having its circumference supported by floatation means, characterised by at least one sensor mounted on the recovery apparatus arranged to generate data in dependence upon at least one characteristic of he oilwater mix, microprocessor means connected to receive data from the sensors, and to generate at least one control signal as a function of the data, control means operable in dependence upon said at least one control signal to control at least one of the level of floatation of the weir skirt, and the speed of operation of the pump.
2. An oil recovery apparatus according to claim 1 wherein the apparatus comprises a sensor for measuring fluid flow rates.
3. An oil recovery apparatus according to claim 2 wherein said fluid flow sensor is located at the pump.
4. An oil recovery apparatus according to claim 2 wherein said fluid flow sensor is located in the pump outlet conduit.
5. An oil recovery apparatus according to any one of the preceding claims comprising a sensor to measure at least one of the following variables: - the hydraulic pressure drop across the pump - the outlet pressure from the pump - the pump liquid temperature - the level of the oil/water mix - the thickness of the oil layer on the surface of the water.
6. An oil recovery apparatus according to claim 5 wherein said sensor or sensors are arranged to provide analogue signals.
7. An oil recovery apparatus according to claim 5 wherein said sensor or sensors are arranged to provide digital signals.
8. An oil recovery apparatus according to any one of the preceding claims wherein the microprocessor means is a multiplex computer card built into a waterproof instrument container on the recovery apparatus.
9. An oil recovery apparatus according to any one of the preceding claims wherein the microprocessor means is mounted remote from the oil recovery apparatus.
10. An oil recovery apparatus according to claim 9 wherein the microprocessor means is mounted on the recovery vessel.
11. An oil recovery apparatus according to any one of the preceding claims wherein the signals from the or at least one sensor, together with any control signals from the microprocessor means are communicated through a fixed link to an onshore control centre.
12. An oil recovery apparatus according to any one of claims 1 to 10 wherein the signals from the or at least one sensor, together with any control signals coming back from the microprocessor means are communicated by a remote link such as infra-red, radio or by satellite to an onshore control centre.
13. An oil recovery apparatus according to any one of the preceding claims wherein the data from the sensors is stored and used for data reporting.
14. An oil recovery apparatus according to any one of the preceding claims wherein the control signals generated as a result of the data measured by the sensors are used to control the weir skirt level, by controlling the height of the top of the skirt from the floats, and thus control the rate of input oil and water.
15. An oil recovery apparatus according to any one of the preceding claims wherein the control signals are used to control the pump speed so as to control the output rate of the oil and water.
16. An oil recovery apparatus according to any one of the preceding claims wherein the control signals are used to effect control of the emulsion breaker injection: either to control the individual doses administered or the timing of the doses or both.
17. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.