GB2527269A

GB2527269A - A method and apparatus for monitoring the volume of oil in an oil storage tank

Info

Publication number: GB2527269A
Application number: GB1405233.6A
Authority: GB
Inventors: Gordon Walker Todd; Michael Denis Bambrick
Original assignee: EMPOWER ENERGY SYSTEMS Ltd
Current assignee: EMPOWER ENERGY SYSTEMS Ltd
Priority date: 2014-03-24
Filing date: 2014-03-24
Publication date: 2015-12-23
Also published as: GB201405233D0

Abstract

A method of remotely monitoring the volume of oil in an oil storage tank 3 is disclosed, said method comprising determining the oil pressure in an outlet conduit 2 communicating with the oil storage tank and calculating the volume and/or level of oil remaining in the tank as a function of the pressure of the oil in said outlet conduit. An apparatus 1 for monitoring the volume of oil in the oil storage tank 3 may comprise a differential pressure sensor 5. The apparatus may further comprise an oil flow meter 6 which may be used to record the flow rate over time. The volume of oil remaining in the oil tank may then also be calculated as a function of the flow rate of oil over time. The calculation of the oil volume as a function of the oil pressure in the outlet conduit may be recalibrated based on the volume of oil calculated as a function of the recorded flow rate.

Description

A Method and Apparatus for monitoring the volume of oil in an oil storage tank This invention relates to a method and apparatus for monitoring the volume of oil in an oil storage tank, and in particular to a method and apparatus for monitoring the volume of oil in an oil storage tank that can be carried out remote from the oil storage tank.

Domestic oil4ired boilers are usually located indoors or on the side of a building. An oil storage tank is typically provided remote from the boiler for storing a supply of fuel oil for a burner of the boiler. Such oil storage tanks are unpressurised, typically relying on gravity to feed fuel to the burner of the boiler through an oil feed pipe.

Some of the issues that arise with such boilers and their remote fuel oil tanks include: 1. Householders have very limited information on the volume and value of fuel oil usage, making tight budgetary control very difficult.

2. Householders may be taken surprise by the low level of oil remaining in the tank, causing financial stress. Furthermore, if the oil storage tank unexpectedly runs dry, airlocks may be formed in the supply to the burner, which may require the oil feed pipe and burner to be bled before it can be used, causing further delay and cost.

3. The value of oil stored in the oil storage tank can be high and the oil is therefore attractive to thieves. This is an increasingly common problem with the increasing cost of oil, especially in rural areas. There is therefore a need to provide a deterrent to thieves and to provide a warning to the user in the event of tampering with the oil storage tank 4. Underfilling of the oil storage tank by the oil delivery firm may go undetected, and can be hard to prove 5. Duplicate fills can occasionally occur, potentially resulting in overflow and significant environmental damage.

Existing oil tank monitoring devices are usually located at the tank, often using ultrasound, floats/buoys or light to measure the oil-level within the tank.

Drawbacks to these known monitoring devices usually include the following: 1. High cost; 2. Low Accuracy; 3. Obvious to thieves, and easily disabled; 4. Not integrated with online energy management or alarm systems, meaning that information may not be readily accessed or processed;

for example:

a. theft alarms are not notified to the owner, unless the owner is present; b. oil refill alerts are not provided; c. timely consumption cost data is unavailable; d. current oil cost comparison is not supported (with other system users) at the time of purchase; e. there are no (or at least very limited) timely alerts and prompts to ensure that waste is minimised; f. consumption and stock data is not incorporated into a comprehensive heating control system.

5. These systems rarely if ever convert fuel level into actual liquid volume remaining, and hence the meaning of the statistics is limited. For example, if a tank is has 5% left in height, this represents only 1.87% of its volume in a typical horizontally mounted cylinder.

It is an object of the present invention to provide an improve method and apparatus for monitoring the volume of oil in an oil storage tank which mitigates the abovementioned problems.

According to a first aspect of the present invention there is provided a method of monitoring the volume of oil in an oil storage tank, said method comprising determining the oil pressure in an outlet conduit communicating with the oil storage tank and calculating the volume and/or level of oil remaining in the tank as a function of the pressure of the oil in said outlet conduit.

Preferably said oil pressure is measured in said outlet conduit at a location remote from the oil storage tank.

The method may comprise the further step of measuring and recording the flow rate of oil in said oil conduit to determine a record of flow rate over time. The method may comprise the further step of calculating the volume of oil remaining in the tank as a function of the recorded flow rate.

In one embodiment the method comprises the step of calibrating volume calculation based the pressure of the oil in said outlet conduit based upon a comparison with the volume calculated as a function of the recorded flow rate.

According to a further aspect of the present invention there is provided an apparatus for monitoring the volume of oil in an oil storage tank comprising a pressure sensor arranged to measure the oil pressure in an outlet conduit communicating with the oil storage tank and processing means for calculating the volume and/or level of oil remaining in the oil storage tank as a function of the oil pressure in the outlet conduit.

Preferably the apparatus comprises a flow meter for recording the flow rate of oil in said outlet conduit, and recording means for recording the flow rate overtime. The processing means may be programmed to calculate the volume of oil remaining in the oil tank as a function of the flow rate of oil over time.

In one embodiment the processing means may be programmed to recalibrate the calculation of the oil volume as a function of the oil pressure in the outlet conduit based upon the volume of oil calculated as a function of the recorded flow rate.

The processing means may be programmed to one or more of the following information to the user:-an estimation of required tank refill date; the current cost to refill tank; an expected dip level (for comparison to an actual measured dip level); the cost of oil consumed over a selected period; self-calibration of the apparatus with respect to the associated oil storage tank (by comparing the consumption/flow rate and oil level data based on oil pressure); timely alerts of low oil to the user; and/or the provision of immediate alerts of potential theft and over/underfilling problems.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 shows a typical domestic oil tank having a monitoring apparatus in accordance with an embodiment of the present invention installed on oil feed line of the tank; Figure 2 shows a modified embodiment of the apparatus of Figure 1 with the flow monitor omitted; Figure 3 is an end profile of a typical domestic oil storage tank; and Figure 4 is a side profile of the oil storage tank of Figure 3.

As shown in Figure 1, a monitoring apparatus 1 in accordance with an embodiment of the present invention has two main elements: 1. A differential pressure sensor 5 for measuring the oil pressure in an oil feed line 2 of an oil storage tank 3 (used to assess the level of oil remaining in the tank).

2. An oil flow monitor 6 arranged to measure the oil flow rate through the oil feed line 2 from the oil storage tank 3 and record the volume of oil consumed over time by an oil-fuelled domestic boiler connected to the oil feed line 2.

The apparatus comprises a processing unit receiving data from the differential pressure sensor 5 and the oil flow monitor 6. The apparatus may include a transmission device whereby the processing unit may communicate with other devices, by means of wireless or wired communication, to enable the apparatus to information to the user, for example via SMS messages, and to allow the apparatus to communicate with and become integrated into a security system of the building.

Having acquired information from the pressure sensor and flow monitor, such data can be processed by the processing unit via a suitable software application (e.g. a web-based application) to permit a host of useful information and features to be communicated to the user, such as: 1. an accurate measurement of the volume and/or level of oil remaining in the tank; 2. a robust estimation of required tank refill date; 3. an accurate current cost to refill tank; 4. an expected dip level (for comparison to an actual measured dip level), which can be requested and checked where there are data integrity queries.

5. the costs of oil consumed by day/weeklmonth, with comparison to: personal budget; ii. similar homes; iii. previous period.

6. permits self-calibration of the apparatus with respect to the associated oils storage tank, by comparing the consumption/flow rate and oil level data (based on oil pressure), to allow an individual look-up table' to be compiled for any shape of tank, as tanks can vary considerably; 7. can provide timely alerts of low oil sent by electronic and traditional methods e.g. SMS, email on the one hand, and sound alarms, phone or even hard copy; 8. immediate alerts of potential theft and over/underfilling problems, preferably via SMS, sound alarms or phone 9. remote monitoring of holiday homes or when absent 10. remote monitoring of old and vulnerable people to stay warm, to de-stress and live within their means, and in conjunction with temperature sensors, to check their comfort levels.

11. ability in a integrated control system to modify heating schedules and alerts to target a specified refill date 12. ability in an integrated energy management system to prompt customers to change behaviour and use available remote controls e.g. when the budget for a day has expired, or the heating has been left on when the house is empty, or when temperatures are dangerously low for occupants or when frozen water pipes are a risk 13. prompt customers to submit anonymous price data at the time of refill, to allow other users in the area to benefit from current indicative oil prices.

Optionally, in an alternative embodiment, as shown in Figure 2, the apparatus can be installed with a connected pressure-sensor device but without the flow monitor, which would be lower cost, but at the expense of many useful features and benefits.

In the embodiment shown in Figure 1, the apparatus 1 is installed on the oil feed line 2, which connects the fuel-oil tank 3 with a boiler 4 located within a building being heated. In most cases the apparatus will be located adjacent the boiler 4, in order to ensure ease of power supply and connection with an energy management system to process the data generated, with for example an RJ1 1 cable to provide the required capability.

The apparatus incorporates a differential pressure sensor 5 for measuring the oil pressure within the oil feed line 2 and a flow monitor 6 for measuring the oil flow rate within the oil feed line. The apparatus includes a processing unit and storage means for processing data from the pressure sensor 5 and flow monitor 6. Data from the flow monitor 6 is recorded over time to provide a record of the oil flow rate overtime, from which record the total volume of oil consumed can be calculated.

The difference between atmospheric pressure and the pressure in the oil feed line 2 resulting from the volume of the oil in the tank is measured by the differential pressure sensor 5. By applying the specific density of the relevant oil 7 to the pressure reading, the processing unit, which may implemented as a cloud-based processor, can convert the analogue pressure reading into a total height difference H between the pressure sensor 5/oil feed line 2 and the oil level in the tank 8. The analogue pressure reading is derived from a voltage proportional to the height of the oil-surface above the sensor, produced by the differential pressure measured by the pressure sensor 5.

Optionally, depending on the particular characteristics of the oil, the processing unit may adjust (or normalise) the density value for temperature variation from the initial measurement point, discussed below regarding Figures 3 and 4. These results are stored in a suitable database for subsequent analysis and presentation to the user.

Figure 1 also shows the flow monitor 6, and the pulse readings from this device are transmitted to the processing unit for accumulation and analysis, based upon the flow monitor's specified volume per pulse, as warranted by the manufacturer's

specifications.

Figure 2 shows the simpler embodiment, wherein a pressure sensor is operated within the device 1, which would reduce cost but also limit the effectiveness of the device.

The pressure readings measured by the pressure sensor 5 may be affected by the operation of boiler. Therefore the normal reduction that indicates the heating is switched on may be learnt' in the software of the processing unit.

Theft detection will remain effective when the boiler is running, but to avoid error, the software will use tank level data collected when the boiler is off.

Figure 3 shows a cross-section of a typical oil tank from the end, and Figure 4 shows a side view. These drawings are considered together in explaining how the pressure data gathered can be compiled into reliable level and volume data.

At the time of installation the engineer will check that the boiler remains off during the calibration process, confirm that the Fuel-Oil Monitor is secured in its permanent location, record the external temperature at the tank, take an image of the oil tank front and side (figures 3 and 4 respectively), measure tank dimensions A, B, C, D (A being the height of the tank, B being the height of the outlet/oil feed line 2, C being the width of the tank, and D being the length of the tank), confirm that the tank contents are standard fuel-oil (i.e. 28 sec kerosene etc.) and finally dip the tank to check the depth of oil. He will then check the pressure reading from the pressure sensor 5, before allowing the boiler to be run. This calibration process does not require any measurements to be undertaken when the tank is either empty or full, but can instead be conducted at a single visit by capturing the data described below.

The calculations for the use of this data, via the processing unit, are as summarised below: 1. apply specific density of relevant fuel oil to convert from the water-based manufacturer's datasheets, to produce a standard reading R that relates to 1 cm of oil. (Where appropriate, R can be normalised for external temperature, to allow for density changes at the prevailing temperature. External temperature can be gained from online sources where no local data is being monitored.); 2. convert the initial pressure reading into the height H, from which E can be deducted to derive the tank outflow 9 tap top height T (the difference between 5 and 9); 3. 1 is multiplied by R to produce the Minimum Pressure Reading N; 4. A is multiplied by R and the result added to N to generate a Maximum Pressure Reading X; 5. The capacity P of the tank is calculated based on its geometry. In the case of figure 3 the area is found by Pi times N2 times C12, and this is multiplied by D; 6. If we have a pressure Observation 0, lying between N and X (minimum and maximum pressure levels), then in the case of a vertically regular shaped tank such as a rectangular solid or a vertical cylinder then this reading can be applied to P to produce the current volume V. i.e. a. 0 less N is the actual height of oil b. divided by the difference between X and N to yield the proportion full F c. multiplied by P to produce V; 7. Most oil tanks are will not exhibit vertical linearity, and therefore the processing unit will use a number of look-up tables to relate implied Dip Value E from a given proportion F. As noted earlier, a 5% F will often yield a V of only 1.87% of P; hence these adjustments are important.

The apparatus is also is capable of subsequent iterative cross-checking and refining by means of comparison of consumption and level data.

Self-calibration is an optional but very useful feature of the apparatus, operating as follows: a. The maximum depth of the oil in the tank is A b. The Usable depth of height is in fact A less B, (with an unusable residue of oil left when the oil is below the outlet); let's call this U. c. By setting up a calibration table of pressure readings for a given tank from B to A in single percentage steps, and capturing the consumption data between each step, it is possible to: Derive an independent empirical look-up table for each individual tank, allowing different shapes' characteristics to be fine-tuned ii. Verify the consistency of data between consumption (from the flow-sensor 6) and level changes (from the pressure sensor 5) iii. Confirm the accuracy of the original measurements at the point of installation.

This method will be especially useful if there are errors in the original calibration measurements or if the tank shape is irregular meaning that the initial look-up table may in fact be an approximation.

There are many optional applications of data derived by the processing unit, especially when combined with an integrated real-time comprehensive energy management system.

In the embodiment shown in Figure 1 the Oil-Flow Monitor 6 is installed on the oil inlet feed at or near the domestic oil-fired boiler. A well-configured self-calibrating flow-meter will convert flow into a pulse for a given volume of liquid flowing through the device. Analysis of the flow-meter readings will allow the domestic consumer to be advised of: * Rate of fuel-oil consumption over selected periods -e.g. minute, hour, day, week, month, season, or year * Comparison to benchmark data -historical, budgetary and other properties * Data on boiler efficiency and potential maintenance and replacement decisions.

The Oil-Fuel Monitor will provide real-time information to domestic consumers to allow them to budget effectively, to change behaviour, to reduce fuel poverty and reduce oil consumption and carbon emissions.

The invention is set in the context of a comprehensive real-time energy monitoring and management system for domestic users. In combination with temperature and/or humidity sensors in the home and external weather data, additionally the system may issue alerts on insulation efficiency and prompts for the risk of mould/moisture problems. In conjunction with heating control, the system may minimise the risk of burst pipes by switching on the heating when appropriate during cold snaps. When applied to the tank level data, the system may provide a rolling forecast of when the oil tank is likely to run out, based on current usage, optionally adjusted for seasonal/weather factors.

Storage, aggregation and analysis of the collected time-stamped oil usage, tank level and temperature data is a useful feature of the Fuel-Oil Monitor in combination with an energy management system, and allows the user to verify their utility and oil bills when convenient, especially in the case of oil at or near the date of refill.

The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention.

Claims

Claims 1. A method of monitoring the volume of oil in an oil storage tank, said method comprising determining the oil pressure in an outlet conduit communicating with the oil storage tank and calculating the volume and/or level of oil remaining in the tank as a function of the pressure of the oil in said outlet conduit.
2. A method as claimed in claim 1, wherein said oil pressure is measured in said outlet conduit at a location remote from the oil storage tank.
3. A method as claimed in claim 1 or claim 2, comprising the further step of measuring and recording the flow rate of oil in said oil conduit to determine a record of flow rate over time.
4. A method as claimed in claim 3, further comprising the step of calculating the volume of oil remaining in the tank as a function of the recorded flow rate.
5. A method as claimed in claim 4, further comprising the step of calibrating volume calculation based the pressure of the oil in said outlet conduit based upon a comparison with the volume calculated as a function of the recorded flow rate.
6. An apparatus for monitoring the volume of oil in an oil storage tank comprising a pressure sensor arranged to measure the oil pressure in an outlet conduit communicating with the oil storage tank and processing means for calculating the volume and/or level of oil remaining in the oil storage tank as a function of the oil pressure in the outlet conduit.
7. An apparatus as claimed in claim 6, further comprising a flow meter for recording the flow rate of oil in said outlet conduit, and recording means for recording the flow rate over time.
8. An apparatus as claimed in claim 7, wherein said processing means is programmed to calculate the volume of oil remaining in the oil tank as a function of the flow rate of oil over time.
9. An apparatus as claimed in claim 8, wherein the processing means is programmed to recalibrate the calculation of the oil volume as a function of the oil pressure in the outlet conduit based upon the volume of oil calculated as a function of the recorded flow rate.
10. An apparatus as claimed in any of claims 7 to 8, wherein the processing means is programmed to one or more of the following information to the user:-an estimation of required tank refill date; the current cost to refill tank; an expected dip level (for comparison to an actual measured dip level); the cost of oil consumed over a selected period; self-calibration of the apparatus with respect to the associated oil storage tank (by comparing the consumption/flow rate and oil level data based on oil pressure); timely alerts of low oil to the user; and/or the provision of immediate alerts of potential theft and over/underfilling problems.
11. A method of monitoring the volume of oil in an oil storage tank substantially as herein described with reference to the accompanying drawings.
12. An apparatus for monitoring the volume of oil in an oil storage tank substantially as herein described with reference to the accompanying drawings.