GB2036290A - Fuel sampling system - Google Patents

Fuel sampling system Download PDF

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Publication number
GB2036290A
GB2036290A GB7845534A GB7845534A GB2036290A GB 2036290 A GB2036290 A GB 2036290A GB 7845534 A GB7845534 A GB 7845534A GB 7845534 A GB7845534 A GB 7845534A GB 2036290 A GB2036290 A GB 2036290A
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GB
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Application
Patent type
Prior art keywords
fuel
control
burner
system
sampling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7845534A
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GB2036290B (en )
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HAMWORTHY ENG Ltd
HAMWORTHY ENGINEERING
Original Assignee
HAMWORTHY ENG LTD
HAMWORTHY ENGINEERING
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N5/00Systems for controlling combustion
    • F23N5/003Systems for controlling combustion using detectors sensitive to combustion gas properties
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N2021/00Pretreatment or prehandling
    • F23N2021/10Analysing fuel properties, e.g. density, calorific

Abstract

A fuel sampling system to give accurate measurements of fluid fuel properties and thereby enable a fuel firing installation to be operated correctly comprises a sample furnace 1 having a fuel sample burner 2 located at one end of the furnace. Fuel and air are fed to the burner via conduits 5 and 6 respectively. A sensor 9 is located in the flue 10 of the furnace 1, and the sensor is connected to an analyser 11 positioned outside the furnace. The analyser is connected to a control loop for controlling quantities of fuel and/or air fed to the fuel sample burner. The analyser can also control quantities of fuel and/or air fed to a main burner of a fuel firing installation. <IMAGE>

Description

SPECIFICATION Fuel sampling system.

This invention relates to a fuel sampling system, and has particular but not exclusive reference to use in fuel firing installations.

In fuel firing installations, it is important to measure, for example, the calorific value and specific gravity of the fluid fuels. Accurate measurements of the fluid fuel properties enable the fuel firing installation to be operated correctly.

A knowledge of fuel properties is required for control of the combustion process, whether by automatic or manual control. Fuel properties, namely the specific gravity and the stoichiometric air requirement for combustion of the fuel, can vary, and it is therefore essential to be able to control the combustion process. By way of example, the overall thermal efficiency of fuel firing installations is partly dependent on minimising the amount of excess air required to complete combustion of the fuel.

Traditionally, the flue products of combustion have been measured for oxygen content, and a feedback signal sent to a combustion control system. Feedback control is used in a closed loop control system, where the controlled variable is measured and the measurement is then used to alter one of the process, variables. The feedback can be achieved by either manual control or automatic control. For example, with manual control, an operator periodically measures a controlled variable if the variable, for example, is below the desired value, the operator can increase the process variable by opening, for example, a valve. With automatic control, a device which is sensitive to the controlled variable produces a signal "pneumatic, electrical etc." proportional to the measured controlled variable.The signal is fed to a controller which compares it with a present desired value or set point. If a difference exists, the controller changes, for example, the opening of a valve to corrrect the controlled variable.

In certain installation, feedback systems are unattractive because of time lags. When measuring the oxygen content of the flue products of combustion, it can also be difficult to obtain a significant flue gas sample.

Control systems for fuel firing installation have in the past used temperature sensing devices or calorimeters for controlling the quantities of fuel or air to the main burner.

According to the present invention, a fuel sampling system comprises a fuel sample bumer, and analyser for analysing gaseous combustion products, the analyser being connected to a control loop for controlling quantities of fuel or air to the fuel sample burner.

By means of the invention, it is possible to produce a signal obtained from the sampling system, which can be used for control of a main burner.

It is an advantage of the invention that full size fuel firing installations can be operated safely.

There are always risks on light-up of main burners without knowing the fuel properties, fuel/air ratios and levels of fuel etc. These operating factors can be found from the use of a fuel sample burner.

Another advantage is that any fuel surges can be accommodated in the sample burner.

It is preferable to use the fuel sampling system in such a way that a signal, obtained from the system, can be interpreted for control purposes on a "feed forward" i.e. anticipatory basis. In a preferred arrangement of the fuel sampling system is located upstream of a main burner. Any changes in fuel properties, fuel/air ratios etc. can be transmitted to the main burner controls via the fuel sampling system control loop before the main burner receives the fuel. In this way, the main burner can be adjusted for optimum firing conditions. The main burner can be adjusted manually or automatically.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in schematic form a basic fuel sampling system; Figure 2 shows in schematic form a complex fuel sampling system; and Figure 3 shows in schematic form a combined fuel sampling system and main burner.

Considering Figure 1, a sample furnace 1 comprises a burner 2 located at one end of the furnace. A fuel sample 3 and air 4 are fed to the burner via conduits 5 and 6 respectively. The fuel sample conduit 5 has a control valve 7; the air conduit 6 has a control valve 8 - both control valves 7 and 8 are fixed pressure controls.

A sensor 9 is located in the flue 10 of the furnace. The sensor 9 is connected to an analyser ii positioned outside the furnace. The sensor detects levels of gaseous combustion products. By way of example, the sensor detects the oxygen level of the combustion products. It will be appreciated that the sensor can detect other gaseous combustion products, such as carbon dioxide.

By way of example, the sensor can comprise a paramagnetic or zirconia element.

The oxygen level as detected by the sensor 9 is fed to the analyser 11, where an output signal corresponding to the oxygen level is generated.

The output signal can either be analogue or digital.

A more complex fuel sampling system is shown in Figure 2. A sample furnace 1 comprises a burner 2 located at one end of the furnace. A fuel sample 3 and air 4 are fed to the burner via conduits 5 and 6 respectively. The fuel sample conduit 5 has a control valve 7; the air conduit 6 has a control valve 8. The air control valve 8 is fixed while the fuel valve 7 is variably controlled.

A sensor 9 is located in the flue 10 of the furnace. The sensor 9 is connected to an analyser 11 positioned outside the furnace. As with the embodiment shown in Figure 1, the sensor 9 detects gaseous combustion products. It can be used to detect, for example, the oxygen or carbon dioxide levels of the combustion products.

The sensor 9, when monitoring oxygen, typically comprises a zirconia or paramagnetic element.

The oxygen level as detected by the sensor 9 is fed to the analyser 11, where an output signal corresponding to the oxygen level is generated.

The output signal can either be by anaiogue or digital.

The control signal from 12 corresponds to the output signal from the basic fuel sampling system as shown in Figure 1. The control signal can then be fed, a further generator 24, to a main burner controller 19 as shown in Figure 3. The main burner controller 19 can then be used to adjust the fuel inlet control valve 20 to the main burner 21.

The output signal from the analyser 11 can also be fed to a controller 13. The controller 13 then compares the output signal with a preset desired value or set point 14, which has been fed into the controller.

The controller is connected mechanically, electrically or pneumatically to the fuel control valve 7 via a line 15.

If a difference exists between the measured output signal and the set point, the controller can alter the valve setting.

A second control signal from 16 gives a valve reading or setting. If the control valve 7 has not been calibrated, the control signal at 1 6 is meaningless.

Therefore, the control valve 7 can be calibrated to represent the ration of the fuel/air quantities present in the furnace flue 10. As shown in Figure 3, the control signal can then be fed to the main bumer controller 19, where it acts as a set point for the controller 19.

A third control signal from 1 7 is available from a pressure transmitter 1 8. The pressure transmitter is connected to the fuel sample conduit 5. A change in pressure in the fuels sample conduit will be transmitted via the pressure transmitter 18 to a metering device, such as a n orifice plate 22, in the main fuel conduit 23 to the main burner 21. The pressure drop across the orifice plate is measured as a function of the pressure transmitted from 17.

Alternatively the signal from 17 may be sent directly to 19 via the function generator 24. In practice, the third control signal (i.e. the signal from 17) will be used to control the main burner in the fuel firing installation.

Normally, the sampling system would receive a fuel sample before the main burner. The sampling system will be upstream of the main burner as shown in Figure 3. However, it could be possible to have the sampling system downstream of the main bumer. However, there will be effectiveiy a time lag, when the sampling system is downstream of the main burner.

The embodiments shown in the drawings have the fuel conduits controlled with the air control valves fixed. However, it is possible to control the air conduits and have the fuel control valves fixed.

The control loop used with the sampling system could be a feedforward control, where process disturbances are measured and compensated for without an indication of a disturbance by a change in a controlled variable. The control loop could also be a feedback control, where information about a controlled variable is fed back as a basis for control of a process variable. It will also be possible to have a combined feedforward and feedback loop.

Claims (9)

1. A fuel sampling system comprising a fuel sample burner, and an analyser for analysing gaseous combustion products of the sample burner, the analyser being connected to a control loop for controlling quantities of fuel and/or air suppiied to the fuel sample burner.
2. A fuel sampling system as claimed in claim 1 , wherein a sensor, connected to the analyser, is arranged to detect levels of gaseous combustion products, such as oxygen or carbon dioxide, in a flue connected to the sample burner.
3. A fuel sampling system as claimed in claim 2, wherein the sensor comprises a paramagnetic or zirconia element.
4. A fuel sampling system as claimed in any preceding claim, wherein an output signal obtained from the analyser of the sampling system is used to control a main burner.
5. A fuel sampling system as claimed in claim 4, wherein a first control signal, corresponding to the output signal from the fuel sampling system, is fed to a main burner controller which adjusts a fuel inlet control valve of the main burner.
6. A fuel sampling system as claimed in claim 4 wherein the output signal is fed to a controller, which compares the output signal with a set point; the controller being connected to a fuel control valve of the fuel sample burner.
7. A fuel sampling system as claimed in claim 5, wherein a second control signal, corresponding to fuel/air ratios in a flue of the main burner, acts as a set point for the main burner controller.
8. A fuel sampling system as claimed in claim 5, 6 or 7, wherein a third control signal, corresponding to a change in pressure in a fuel sample conduit, is fed by a pressure transmitter to a metering device in the main fuel conduit to the main burner and, thereby generates a further signal for controlling the main burner.
9. A fuel sampling system substantially as herein described with reference to the accompanying drawings.
GB7845534A 1978-11-22 1978-11-22 Fuel sampling system Expired GB2036290B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7845534A GB2036290B (en) 1978-11-22 1978-11-22 Fuel sampling system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7845534A GB2036290B (en) 1978-11-22 1978-11-22 Fuel sampling system

Publications (2)

Publication Number Publication Date
GB2036290A true true GB2036290A (en) 1980-06-25
GB2036290B GB2036290B (en) 1982-12-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB7845534A Expired GB2036290B (en) 1978-11-22 1978-11-22 Fuel sampling system

Country Status (1)

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GB (1) GB2036290B (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2486204A1 (en) * 1980-07-04 1982-01-08 Snam Spa Method of controlling the thermal power of a plant fed with natural gas having a varying calorific value, and apparatus suitable for this application
EP0055852A1 (en) * 1980-12-27 1982-07-14 Hitachi, Ltd. Method and apparatus for controlling combustion of gasified fuel
EP0075369A1 (en) * 1981-09-18 1983-03-30 N.V. Nederlandse Gasunie Method and device for keeping the heat load on gas-fired equipment constant
US4449918A (en) * 1981-07-06 1984-05-22 Selas Corporation Of America Apparatus for regulating furnace combustion
DE3408397A1 (en) * 1984-03-08 1985-09-19 Ruhrgas Ag Method and arrangement for determining the mischungsverhaeltnisses of a sauerstofftraegergas and a fuel-containing mixture
FR2588061A1 (en) * 1985-10-02 1987-04-03 Brunel Gerald Process and installation for regulating the combustion of a gas burner of a heat or force generator such as a boiler or the like, to obtain a specific combustion
EP0221799A1 (en) * 1985-10-02 1987-05-13 Societe D'etude Et De Construction De Chaudieres En Acier Seccacier Gas burner combustion regulation method and apparatus for a heat or force generator, especially a boiler or the like, to obtain a specific combustion
US4815965A (en) * 1983-05-12 1989-03-28 Applied Automation, Inc. Monitoring and control of a furnace
EP0421251A2 (en) * 1989-10-03 1991-04-10 Ente Nazionale Per L'energia Elettrica - (Enel) Method for measuring the efficiency of a combustion and an apparatus for carrying out the method
FR2712961A1 (en) * 1993-11-26 1995-06-02 Lorraine Laminage Set in real time from one burner to varying characteristics of fuel, particularly for metallurgical reheat furnace.
EP2725355A1 (en) * 2012-10-25 2014-04-30 Axetris AG Method and device for measurement of the heating value of a gas stream

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3125515A1 (en) * 1980-07-04 1982-03-25 Snam Spa Method for controlling the waermebelastung a plant
FR2486204A1 (en) * 1980-07-04 1982-01-08 Snam Spa Method of controlling the thermal power of a plant fed with natural gas having a varying calorific value, and apparatus suitable for this application
EP0055852A1 (en) * 1980-12-27 1982-07-14 Hitachi, Ltd. Method and apparatus for controlling combustion of gasified fuel
US4449918A (en) * 1981-07-06 1984-05-22 Selas Corporation Of America Apparatus for regulating furnace combustion
EP0075369A1 (en) * 1981-09-18 1983-03-30 N.V. Nederlandse Gasunie Method and device for keeping the heat load on gas-fired equipment constant
US4815965A (en) * 1983-05-12 1989-03-28 Applied Automation, Inc. Monitoring and control of a furnace
DE3408397A1 (en) * 1984-03-08 1985-09-19 Ruhrgas Ag Method and arrangement for determining the mischungsverhaeltnisses of a sauerstofftraegergas and a fuel-containing mixture
EP0156200A1 (en) * 1984-03-08 1985-10-02 Ruhrgas Aktiengesellschaft Method of and device for determining the mixing ratio of a mixture containing an oxygen carrier and a fuel
US4659306A (en) * 1984-03-08 1987-04-21 Ruhrgas Aktiengesellschaft Method of and system for determining the ratio between the oxygen-carrying gas content and the fuel content of a mixture
FR2588061A1 (en) * 1985-10-02 1987-04-03 Brunel Gerald Process and installation for regulating the combustion of a gas burner of a heat or force generator such as a boiler or the like, to obtain a specific combustion
EP0221799A1 (en) * 1985-10-02 1987-05-13 Societe D'etude Et De Construction De Chaudieres En Acier Seccacier Gas burner combustion regulation method and apparatus for a heat or force generator, especially a boiler or the like, to obtain a specific combustion
EP0421251A2 (en) * 1989-10-03 1991-04-10 Ente Nazionale Per L'energia Elettrica - (Enel) Method for measuring the efficiency of a combustion and an apparatus for carrying out the method
EP0421251A3 (en) * 1989-10-03 1991-06-05 Ente Nazionale Per L'energia Elettrica - (Enel) Method for measuring the efficiency of a combustion and an apparatus for carrying out the method
US5155047A (en) * 1989-10-03 1992-10-13 Enel - Ente Nazionale Per L'energia Elettrica Method and apparatus for measuring and controlling efficiency of a combustion
FR2712961A1 (en) * 1993-11-26 1995-06-02 Lorraine Laminage Set in real time from one burner to varying characteristics of fuel, particularly for metallurgical reheat furnace.
EP0661499A1 (en) * 1993-11-26 1995-07-05 Sollac S.A. Real time control of a burner for gases with differing characteristices, especially for a metallurgical furnace for reheating
EP2725355A1 (en) * 2012-10-25 2014-04-30 Axetris AG Method and device for measurement of the heating value of a gas stream
US20140119400A1 (en) * 2012-10-25 2014-05-01 Axetris Ag Method and device for measurement of the heating value of a gas stream
CN103776800A (en) * 2012-10-25 2014-05-07 阿克塞特里斯股份公司 Method and device for measurement of the heating value of a gas stream

Also Published As

Publication number Publication date Type
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