WO2012128609A1

WO2012128609A1 - An improved fuel blending system and method

Info

Publication number: WO2012128609A1
Application number: PCT/MY2012/000060
Authority: WO
Inventors: Manirajan K. KARUPPAN; Hamdan ABU HASAN; Ahmad Basri ABU BAKAR; Rahim A OTHMAN; Ahmad Sharman SHARIF; Samsuddin B A RAHMAN; Adlee B ABU BAKAR
Original assignee: Petroliam Nasional Berhard (Petronas)
Priority date: 2011-03-23
Filing date: 2012-03-22
Publication date: 2012-09-27
Also published as: WO2012128609A8; MY176961A

Abstract

A system 300 for blending of fuel from a plurality of components 395, comprising a blend property control 315 for establishing a ratio of the components required to meet properties of a blended fuel specification; a blend ratio control 335, in communication with the blend property control, for maintaining the component ratio; an analyzer array and sampling system 355, in communication with the blend ratio control 335 analyzing fuel during the blending process in order to determine actual properties of the blended fuel; wherein the system 300 is arranged to permit the actual properties to be communicated to the blend property control 315, said blend property control 315 arranged to compare the actual properties with the blended fuel specification properties and to calculate a revised component ratio required to adjust the blend fuel 405 to meet the blended fuel specification.

Description

AN IMPROVED FUEL BLENDING SYSTEM AND METHOD Field of the Invention The invention relates to the blending of automotive and aviation fuel to a predetermined specification. In particular, the invention relates to a system to more accurately derive batch of blended fuel in light of the predetermined specification.

Background

In the blending of product for commercial or retail sale of gasoline, each product is required to meet a certain specification. For instance, a gasoline product sold at retail petrol stations includes a ULG97 product Gasoline meeting this specification is therefore required to be blended from constituent components in order to meet this specification. Because of the difficulties and inaccuracies in ensuring a certain specification is met, a target above this specification is set for instance in the case of an ULG97 the target blend may be 97.4. As a consequence, the deviation from the specification represents a loss on the basis that payment is made based on the specification, not any over-specification target that is met. If a specification is not met for a particular blend then the entire batch must be rejected and re-blended. It should be noted that a particular batch may be as much as one hundred thousand barrels and so constituting a considerable volume. Further, if the target blend substantially exceeds the specification, then selling the over-specification product as the specification product may be uneconomic and so the batch again would be re-blended.

Accordingly, the desired process aims to minimize the band between the specification and the acceptable over-specification, whilst avoiding an under-specification product as well as an uneconomic over-specification product.

The blending process according to the prior art involves the component fuels being directed to a blender under the control of a Distributed Control System. The DCS includes a blend ratio control for tank quality estimation and an end of blend certification. The components are directed to the blender according to a fixed set of blend ratios, or recipe, based on the specification for the particular batch. During the blending, samples are taken from the blender after two hours and again at 50% of the total batch and finally at the end of the batch with all three being directed to a laboratory in order to determine whether the batch meets specification. If so, then a certificate of quality will be issued.

It is not uncommon for the time taken between a sample being taken and the laboratory yielding a result to be as much as six hours. Thus, should the laboratory detect an out of specification batch at least six hours of product will need to be re-blended and possibly the entire batch based upon which sample yields the out of specification result. Summary of Invention

In a first aspect the invention provides a system for blending of fuel from a plurality of components, comprising a blend property control for establishing a ratio of the components required to meet properties of a blended fuel specification; a blend ratio control, in communication with the blend property control, for maintaining the component ratio; an analyzer array and sampling system, in communication with the blend ratio control analyzing fuel during the blending process in order to determine actual properties of the blended fuel; wherein the system is arranged to permit the actual properties to be communicated to the blend property control, said blend property control arranged to compare the actual properties with the blended fuel specification properties and to calculate a revised component ratio required to adjust the blend fuel to meet the blended fuel specification. In a second aspect the invention provides a method for creating a blended fuel from a plurality of components, the method comprising the steps of: providing an initial fuel specification having required properties for the blended fuel; calculating an initial ratio of the plurality of components required to meet the specification; commencing the blending process whilst maintaining the initial ratio of the components; measuring actual properties of a partially blended fuel during the blending process and transmitting the measurements to a control system; said control system comparing the actual properties with the required properties of the specification, and calculating an adjusted ratio of components so as to vary the actual properties of the partially blended fuel to the required properties of the specification; said control system further maintaining the adjusted ratio of the components; and so converging the properties of the partially blended fuel with the properties of the specification.

In a third aspect the invention provides a method for validating an analyzer arranged to monitor a fuel blending process, the method comprising the steps of: Interrogating said analyzer using a reference sample applicable to said analyzer to receiving a result from said interrogation; transmitting said result to a Analyser Management and Data Acquisition System (AMADAS), and comparing the result with a reference value; said AMADAS validating the analyzer if said result is within an acceptable range of the reference value, or; failing said analyzer if said result is outside said acceptable range.

In a fourth aspect the invention provides a system for testing a condition for the release of product following a fuel blending process, comprising: a data acquisition system for interrogating said analyzer using a reference sample applicable to said analyzer; a blend ratio control, in communication with the data acquisition system, for receiving the validation result from said data acquisition system; wherein said blend ratio control is arranged to compare the validation result with a reference value, and validate the analyzer if said validation result is within an acceptable range of the reference value, or failing said analyzer if said result is outside said acceptable range.

The invention therefore provides means by which the conformity of the blended fuel to the required specification is monitored and adjusted during the process. This is advantageous over the prior art which only permits determining an outcome after the completion of the process or, at best, having the ability to scrap a batch part way through the process. The present invention has the capability of amending a partial blend, whether caused by an error in component variation or due to an analyzer fault, during the blending process. Further, in a different aspect, the invention provides for the detection of analyzer faults during the blending process. This has the advantage of finding a fault much earlier and so being able to manually, or automatically, address the consequences of the analyzer fault during the blending process, rather than discovering a non-specification batch after blending.

It will be appreciated that the various aspects of the present invention may be used together or in isolation from each other, depending on the requirements of the process.

In one embodiment, any one or a combination of the blend property control, blend ratio control and data acquisition system may be controlled by a distributed control system (DCS). In this case, the system of controllers may be connected by networks for communication and monitoring. To this end, the DCS system may act as a central control. In particular, it may control the devices such as fast loop pumps, sample conditioning valves, recovery system, sample grabbing, VRM Vessel modes etc.

In one embodiment, the DCS may execute the blend sequence, which may include committing equipment, initiating analyzer pre-validation, ramp-up and continue blending till the target volume is reached. At the blend close, the system may initiate the post-validation for all, or some, of the analyzers. In a further embodiment, the DCS may check for release conditions and generate an End of Blend Report (EOB). The DCS may send the EOB report to the Laboratory Information Management System (LIMS) to issue a Certificate of Quality (COQ).

An Analyzer Management and Data Acquisition System (AMADAS) may be installed to perform Statistical Quality Control (SQC), such as to ASTM 3764-01, on

conventional analyzer measurement for Validation Reference Material during analyzer validation and give validation fail/passed feedback to DCS.

AMADAS may also archive the analyzer validation data and plot control chart for long term analyzer performance monitoring. For example, the analyzers used for the blending process may include FTNIR, sulphur analyzers, Reid Vapour pressure (RVP) analyzers.

In the case of FTNIR analyzers, these may be validated as per ASTM 6122, using toluene & pentane. A pass / fail flag, possibly with the relevant Mahalanobis distance, may be sent to AMADAS for archiving and plotting a control chart. Brief Description of Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1 is a flow diagram for blending a fuel according to one embodiment of the present invention;

Figure 2 is a flow diagram for validating analyzers in a fuel blending process according to an embodiment of the present invention; Figure 3 is a schematic of a fuel blending system according to a further embodiment of the present invention.

Detailed Description The invention improves upon the prior art through the ability to monitor the blending process and adjust the partially blended fuel prior to the final volume being reached and so more accurately adhering to the relevant specification. Accordingly, batches of blended fuel are substantially less likely to be rejected through under specification or to be uneconomical through an over specification batch.

To this end Figure 1 shows a process according to one embodiment of the present invention whereby an initial fuel specification 105 such as a recipe taken from an offline recipe database, such as Blend 2000, is entered into the control system 110. In this case, the control system may be a Blend Property Control that acts to optimize the blended fuel in light of the downloaded specification.

The control system 110 calculates the required ratios of the component fuel which is then downloaded to a Blend Ratio Control (BRC) 115 which acts to monitor the process and maintain the required ratios as specified by the Blend Property Control (BPC) 110. On commencement of the process, the system interrogates the blend tank to determine whether the target volume has been reached 120. If it has been reached 122 then the process terminates, at which time the reporting cycles may begin.

If the target volume has not been reached 123, the BRC receives measurement data on the properties of the partially blended fuel 125 which then is compared 130 to the properties of the required specification. If the actual properties meet the specification properties 132 then the process feeds back to the target volume interrogation 120 and either continues 123 or terminates 140.

If, however, the required specification properties are not met 133, the BPC recalculates 135 a new component ratio which is required in order to converge the partially blended fuel properties to the required specification properties. This is then looped back to the BRC 137.

Thus, by adding the feedback loop this allows the BPC to optimize the final fuel batch, which reduces or eliminates the need for re-blending of the final blended fuel batch. Figure 2 shows a further aspect of the present invention relating to a process for validating a fuel property analyzer used in the blending of fuel components. It will be appreciated that the process according to Figure 2 may be achieved prior to the commencement of the blending process or on completion of the blend at which the volume target has been reached. Alternatively, the validating process may be implemented either automatically or under operator control at any stage during the blending process.

Thus, a validation request 205 is made either as a result of an operator instruction from a DCS screen or from the AMADAS. The validation process according to Figure 2 may be applied to the fuel blending process of Figure 1. Alternatively, the process of Figure 2 may be applied to different fuel blending processes including those of the prior art to enhance the yielded fuel blend. The control system commences the sequence 210 by determining 215 whether a prior validation process has been undertaken within a predetermined period. In this embodiment, the predetermined period may be 8 hours. If the validation is less than 8 hours old, the result from the prior validation is forwarded to the DCS which will determine whether the previous validation was successful 250 or unsuccessful 240 and take the appropriate steps.

If however the validation is older than 8 hours then a new validation process is commenced. The precise nature of the validation will be determined by the type of analyzer being assessed. By way of a non-limiting example, the analyzer may be one or a combination of FTNIR, sulphur analyzers, Reid Vapour pressure (RVP) analyzers.

For instance, if the analyzer being validated is an FTNIR then an evaluation of the analyzer against a reference material, or sample, may involve comparing the output spectrum of the FTNIR to a reference material spectrum, assessing such criteria as linearity, ice formation, modulation, loss of intensity, spectra noise, modulation efficiency and purging. The comparison of the expected spectra of a fully operational FTNIR compared to that of the analyzer being validated will determine whether a pass or fail is determined.

The process then is reapplied to the question of whether the analyzer is validated 250 or whether it fails 240. If the analyzer is validated the ratio control system continues the batch and if not then the ratio control system is able to undertake any one of several actions. For instance, the ratio control system may ignore the non- validation of the analyzer. Alternatively, the analyzer may be taken offline and so reduce the number of analyzers being used for the blend process. In a further alternative, an operator may isolate the results from the analyzer for later determination as to whether the results are valid or not.

The AMADAS may conduct the Statistical Quality Control (SQC) and generate the flags indicating validation passed or failed. The SQC may be done as per ASTM 3764. The purpose of the SQC is to ensure that the analyzer performance is in statistical control over the long term in terms of precision and bias. The SQC may include the statistical treatments like F test, t Test, repeatability test, normality test, control charting etc. When the analyzer validation fails then AMADAS will indicate / log the reason of failure (such as F test failed, T test failed etc.). Alternatively, the validation may not need SQC treatment. The success or failure of the validation, depending upon the analyzer in question, may be determined by the analyzer itself whereupon it will generate a relevant flag. However, Mahalanobis Distance (MD values) may be sent to the AMADAS for trending purposes. The availability of a valid analyzer may depend upon a determination of criteria, including but not limited to the following. If any of the following error conditions occur then the analyzer will be considered as unavailable:

1. Is the analyzer is online?

2. Is there a "Low flow" alarm?

3. Is there an "Analyzer Outlier Alarm" whereby the analyzer identifies data that lies significantly outside the expected range?

4. Is the BRC Property validation passed? The BRC may check the validity of each property value from each analyzer for various error conditions.

With reference to Figure 3, a system 300 is shown comprising a DCS 330 incorporating a BPC 315 in communication with a BRC 335. An AMADAS 340 is linked between the BRC 335 and an analyzer array 355, which includes FTNIR 345, RVP 350 and sulphur 360 analyzers. The array 355 is connected through a sequence control system 390 to monitor a fuel blending process. Here, a plurality of fuel components 395 are blended according to a ratio determined from a recipe database 310 in order to meet a desired fuel specification for a finished product 405. A benefit of the sampling system 365 is the availability of the results to an operator of the DCS 330, whereby in the case of the blending system undergoing significant variance from the specification through an equipment failure or substantial component variation, the operator is able to halt or modify the process in real time, rather than having to wait until a break in the process or until after the blending process is complete.

The AMADAS 340 functions to assess the validity of the analyzer array, as is described with regard to the embodiment of Figure 2.

On successful completion of the blending process, including a successful report from the AMADAS on the assessment of the analyzer array 355, the DCS 330 then produces an End of Blend 325 report culminating in the Certificate of Quality 385 being issued from the Laboratory Information Management System 380.

Claims

1. A system for blending of fuel from a plurality of components, comprising

a blend property control for establishing a ratio of the components required to meet properties of a blended fuel specification;

a blend ratio control, in communication with the blend property control, for maintaining the component ratio;

an analyzer array and sampling system, in communication with the blend ratio control analyzing fuel during the blending process in order to determine actual properties of the blended fuel;

wherein the system is arranged to permit the actual properties to be

communicated to the blend property control, said blend property control arranged to compare the actual properties with the blended fuel specification properties and to calculate a revised component ratio required to adjust the blend fuel to meet the blended fuel specification.

2. The system according to claim 1, further including a sampling system, in

communication with the blend ratio control, for sampling fuel during the fuel blending process.

3. The system according to claim 1 or 2, further including a distributed control system arranged to act as a master control for the blend property control and blend ratio control. The system according to any one of claims 1 to 3, further including an analyzer validation system for determining the validity of each analyzer in the analyzer array such that only properties determined by analyzers validated by the validation system are communicated to the blend property control.

A method for creating a blended fuel from a plurality of components, the method comprising the steps of: providing an initial fuel specification having required properties for the blended fuel;

calculating an initial ratio of the plurality of components required to meet the specification;

commencing the blending process whilst maintaining the initial ratio of the components;

measuring actual properties of a partially blended fuel during the blending process and transmitting the measurements to a control system;

said control system comparing the actual properties with the required properties of the specification, and calculating an adjusted ratio of components so as to vary the actual properties of the partially blended fuel to the required properties of the specification;

said control system further maintaining the adjusted ratio of the components; and so converging the properties of the partially blended fuel with the properties of the specification. The method according to claim 5, further including the step of repeat steps measuring, comparing, calculating, maintaining and converging steps until a target volume of the blended fuel is reached.

A method for validating an analyzer arranged to monitor a fuel blending process, the method comprising the steps of:

interrogating said analyzer using a reference sample applicable to said analyzer to receiving a result from said interrogation;

transmitting said result to a Analyser Management and Data Acquisition System (AMADAS), and comparing the result with a reference value;

said AMADAS validating the analyzer if said result is within an acceptable range of the reference value, or;

failing said analyzer if said result is outside said acceptable range.

The method according to claim 7, further including the step of providing a data acquisition system for performing the interrogating and transmitting steps.

The method according to claim 7 or 8, wherein said validation is performed prior to commencement of the blending process.

The method according to any one of claims 7 to 9, wherein said validation is performed during the blending process. The method according to any one of claims 7 to 10, wherein said validation is performed on reaching a target volume of blended fuel.

A system for testing a condition for the release of product following a fuel blending process, comprising: a data acquisition system for interrogating said analyzer using a reference sample applicable to said analyzer;

a blend ratio control, in communication with the data acquisition system, for receiving the validation result from said data acquisition system;

wherein said blend ratio control is arranged to compare the validation result with a reference value, and validate the analyzer if said validation result is within an acceptable range of the reference value, or failing said analyzer if said result is outside said acceptable range.

The system according to claim 12, wherein said analyzer is one within of analyzers.