GB2285227A - Burner system with static mixer for forming dispersion of fuel and water - Google Patents
Burner system with static mixer for forming dispersion of fuel and water Download PDFInfo
- Publication number
- GB2285227A GB2285227A GB9324648A GB9324648A GB2285227A GB 2285227 A GB2285227 A GB 2285227A GB 9324648 A GB9324648 A GB 9324648A GB 9324648 A GB9324648 A GB 9324648A GB 2285227 A GB2285227 A GB 2285227A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fuel
- water
- burner
- liquid fuel
- dispersion
- 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
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/04—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying action being obtained by centrifugal action
- F23D11/06—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying action being obtained by centrifugal action using a horizontal shaft
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/30—Injector mixers
- B01F25/31—Injector mixers in conduits or tubes through which the main component flows
- B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
- B01F25/3131—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit with additional mixing means other than injector mixers, e.g. screens, baffles or rotating elements
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
- C10L1/328—Oil emulsions containing water or any other hydrophilic phase
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/10—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour
- F23D11/16—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour in which an emulsion of water and fuel is sprayed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K5/00—Feeding or distributing other fuel to combustion apparatus
- F23K5/02—Liquid fuel
- F23K5/08—Preparation of fuel
- F23K5/10—Mixing with other fluids
- F23K5/12—Preparing emulsions
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Liquid Carbonaceous Fuels (AREA)
Abstract
A burner system employing a dispersion of liquid fuel and water, wherein liquid fuel (6) and water (4) /non-ionic surfactant (5) are passed into a static mixer (3) at a temperature below 180 DEG C to produce minimally stable droplets of fuel and water. The resultant dispersion (8) is passed into an atomiser (1) where it interacts with the atomising fluid (7) and is ignited and combusted. The presence of a non-ionic surfactant in the water ensures that the dispersion is of the oil-in-water type as it leaves the burner tip. The fuel/water ratio is in the range 70/30 - 90/10 by vol. The surfactant concentration is 0.01 - 1.0% by vol based on the fuel. <IMAGE>
Description
- U U S
BURNER
The present invention relates to burners and more particularly relates to burners for the combustion of liquid fuels.
The combustion of liquid fuels for heat raising purposes is usually preceded by the break up of the liquid fuel into small droplets. This may be achieved for example by the use of an atomisation device. The device uses the energy provided by high fuel pressure discharge, moderate fuel pressure in conjunction with an atomising fluid such as air, steam or fuel gas, or by centrifugal force with high velocity air. The resultant combustion efficiency and the emissions generated are dictated by burner design, the method of operation and fuel quality. Fuel treatment can improve combustion performance and reduce emissions, one technology being the use of emulsions.
The emulsification process can be used for extending the availability of these liquid fuels, which otherwise would not be suitable for the combustion kit generally available.
Additionally, emulsions can increase efficiency of combustion and reduce noxious burner emissions. The following examples have been used on a commercial or experimental scale (a) a mixing device such as a static mixer, ultrasonic dispersator, turbine mixer, or high shear pump is used to produce a water-in-oil emulsion containing < 10% of water. The product emulsion is immediately combusted. The technique is relatively simple and can provide an improvement in solids emission content relative to untreated liquid fuel. However it does not give any handling advantages, indeed the viscosity of the fuel can increase unpredictably, and has unreliable effects on carbon burn-out and emissions reduction.Also it is virtually ineffective with some fuels (b) more recently a further type of emulsion fuel known as Orimulsionmf has been developed and commercialised. The emulsions are formulated for maximum stability so that they can be transported large distances without coalescing and combusted many months after their preparation. This stability is achieved by extensive use of surfactants and careful control of the emulsifying process to achieve relatively small droplet size.
The present invention relates to a method for producing liquid fuel/aqueous liquid dispersions, in contrast to emulsions, which have all the benefits of improved combustion characteristics, are relatively inexpensive and less complex to prepare than those of prior art emulsion procedures.
Thus according to the present invention there is provided a burner system comprising a burner capable of burning a dispersed fuel and a mixer for producing a dispersion of a liquid fuel and an aqueous liquid.
The invention also includes a method for producing a dispersion of fuel oil and an aqueous liquid suitable for use in a burner which comprises passing a liquid fuel and a an aqueous liquid into respective inlets of a mixer, preferably at a temperature of less than or equal to 1 800C, whereby a heterogeneous phase of liquid fuel dispersed in an aqueous liquid is produced in the form of droplets.
The method produces a relatively unstable dispersion rather than a stable emulsion. An emulsion is defined as a heterogeneous system comprising at least one immiscible liquid intimately mixed with another in the form of droplets of diameter in general exceeding 0.1 microns. These emulsion systems are often stabilised by use of surface active agents and can be transported long distances and stored over long periods of time before they are used. A dispersion is defined as a heterogeneous system comprising oil dispersed in an aqueous liquid such as water in the form of droplets of diameter exceeding 1 micron. These dispersions possess minimal stability even in the presence of additives such as surface active agents and cannot be transported long distances or stored for long periods of time.In fact, were the products of the dispersion making process to be pumped into storage, the stored material would separate into its component parts within 24 hours. The presence of the surface active agent is essential, however, not for stability purposes, but to ensure that the dispersion is of the oil-in-water type as it exits the burner tip.
The burner is capable of combusting a liquid fuel such as a hydrocarbon oil and is preferably an atomising burner.
The mixer for producing the dispersion may be a static mixer or similar device.
Dispersions of liquid fuel in aqueous fluid are produced by introducing the appropriate quantities of liquid fuel, aqueous fluid and surfactant to the mixer which is located inline as close as possible to the atomiser or burner head.
The aqueous liquid is preferably water.
The liquid fuel/water compositions are in the range 70/30 to 90/10 by volume and are preferably in the range 75/25 to 85/15.
The surfactant concentration is in the range 0.01 to 1.0 % based on liquid fuel by volume and is preferably in the range 0.06 to 0.2%.
The invention will now be described by way of example only and with reference to the accompanying drawings.
Figure 1 is a schematic diagram of a burner for combusting dispersions of liquid fuel and water.
Figures 2a and 2b represent partial vertical sections through a dispersion burner showing alternative locations for the mixer. Figure 2a shows a burner having an axial tube mixer arrangement and figure 2b shows a burner having a coaxial tube mixer arrangement.
Figure 3 is a partial vertical section through a typical static mixer for producing dispersions of liquid fuel and water.
Figure 4 is a partial vertical section through a rotary cup atomising burner having a mixer for producing dispersions of liquid fuel and water.
In figure 1, the burner has an atomiser head 1 connected to a lance 2. A mixer 3 is located within the burner lance and has inlets for water 4 and surfactant 5 and liquid fuel 6 and atomising fluid 7 feeds. In use, water/surfactant and liquid fuel are passed in the appropriate quantities into a static or motionless mixer which produces a dispersion of liquid fuel and water downstream 8 of the mixer 3. This dispersion is passed into the atomiser 1 where it interacts with the atomising fluid 7 and is ignited and combusted 9.
Figure 2a shows a dispersion burner having an axial mixer 10. The burner lance is in the form of a pair of coaxial tubes, the inner tube 11 transporting liquid fuel and having a mixer 10 and the outer annular tube 12 for transporting the atomising fluid 7 e.g.
pressurised steam, which enters via feed tube 13. Tube 14 conveys the water/surfactant to the mixer 10. Alternatively a mixer 15 with water/surfactant entry 16 may be positioned in the liquid fuel feed tube 17.
Figure 2b shows a dispersion burner having a coaxial or annular mixer 18. The burner lance is in the form of a pair of coaxial tubes, the inner tube 19 for transporting the atomising fluid 7 via entry tube 20 and the outer or annular tube incorporating a mixer 18. Tube 22 conveys the water/surfactant to the annular mixer 18. Alternatively a mixer with water/surfactant entry 24 may be positioned in the liquid fuel feed tube 25.
In figure 3, water and surfactant in appropriate proportions are injected into the entry face of an axial static mixer 26 through a nozzle 27 which abuts this face 28 and which is designed to impart a fluid velocity equal to that of the surrounding liquid fuel flow 29. The atomising fluid passes along the outer annular tube to the atomising head (not shown).
In figure 4, the mixer illustrated in figure 3 is incorporated into the liquid fuel feed tube 30 so that the dispersion passes over the rotating cup 31 and into the atomising air stream 32 and combustion air flow 32.
The liquid fuel is desirably at a temperature less than or equal to 180 OC otherwise the dispersion may not form due to changes in the surfactant's properties with temperature. Also it is desirable to minimise the amount of solids present in the liquid fuel prior to the dispersion forming process and it is preferred to filter the liquid fuel, for example, normal industrial oil filtration according to BS 799.
Water can be used directly from the local mains supply or it may be softened if required. Also steam condensate is a suitable source for the water phase.
Alternatively the present invention provides an opportunity for disposal of contaminated water especially where the contaminants are hydrocarbons and/or combustible fluids.
The surface active agent or surfactant is soluble in water (containing fluids) and is preferably non-ionic although it may be possible to use anionic and cationic surfactants. The preferred surfactants are the nonyl phenol ethoxylate series of nonionic surfactants comprising C9Hl9 C6H4(OC2H4)nCH3 where n = 10 to 100. The preferred value of n is 15 to 40. The surfactant may be used as a concentrate comprising 80% of surfactant dissolved in water. Other chemical additives e.g.
combustion improving chemicals, can also be introduced together with the surfactant provided that there is compatibility with the relevant phases present. Compatible surfactant tailoring can also be used where required to deal with high temperature ash deposition and corrosion from certain types of liquid fuel.
The static or motionless mixer used may be of the recognised type produced by manufacturers such as Sulzer, Kenics, or Lightnin'. A typical static mixer would be the
Sulzer SM-X or SM-V depending on the viscosity of the liquid fuel phase to be dispersed. Static mixer size will be dependent on the relative amounts of liquid fuel and water to be mixed and their total throughput in the system.
It is envisaged that the present invention can be used, for example, in the production of dispersions for use in twin fluid atomising burner systems, rotary cup burners, and heavy oil engines, gas turbines or with the preceding for the disposal of contaminated water.
The present invention is a unique combination of additive, emulsification and dispersion techniques which is different to, and offers advantages over those in the prior art. These differences and advantages are described below:
The addition of water to the liquid fuel offers the following combustion advantages (a) it reduces pollutant emissions and has better carbon burn-out with lower NOx, (b) it enables cleaner combustion of cheaper heavier fuels, (c) it preserves cleaner heat transfer surfaces within both radiant and convection heat transfer zones, thereby reducing fuel and ash deposit removal. Currently these advantages can be obtained by injecting small amounts of water (up to c.a. 10%) into the liquid fuel to form water-inoil emulsions just before combustion.
The present invention which is an oil-in-water system offers the following advantages over an water-in-oil system (a) it has greater pollutant reduction, including lower NOx, and better carbon burn-out (b) it has cleaner combustion down to ash levels and suitable for a wider range of cheaper heavier liquid fuels (c) it maintains cleaner heat transfer surfaces, and less fuel and ash deposit removal (d) it has more consistent and controllable results (e) it allows lower excess air operation which offers improved efficiency (f) it reduces fuel preheat requirement (g) it has near constant viscosity at burner tip, independent of liquid fuel viscosity (h) any spillage is normally water soluble (i) it provides the facility to introduce a range of water soluble additives to modify combustion, ash deposits or emissions and (j) it avoids use of rotating machinery or ultrasonic devices for mixing purposes.
The majority of the above combustion improvements and emissions reductions can be obtained by the use of a pre-prepared oil-in-water emulsion fuel. However the present invention offers the following additional advantages over the use of pre-prepared emulsion fuels (a) it does not require the expensive preparation and shipping costs (significant water concentration) of emulsions with long term stability (b) it requires only moderate water concentrations (c) it requires only minimal surfactant concentration (d) the dispersions may be generated by maintenance free static/motionless mixers (e) the device may be incorporated within or close to the burner gun (f) it does not restrict normal fuel combustion and (g) it does not require dedicated market distribution facilities.
Some of the differences between dispersions produced by the present invention, and conventional oil-in-water emulsion fuels are (a) they have transient stability (b) they are formed by a single stage process and (c) surfactant concentration is substantially reduced.
Claims (18)
1. A burner system comprising a burner capable of burning a dispersed fuel and a mixer for producing a dispersion of a liquid fuel and an aqueous liquid.
2. A burner system according to claim 1 in which the burner is an atomising burner.
3. A burner system according to claim 1 or claim 2 in which the mixer is a static mixer or equivalent.
4. A burner system according to any of the preceding claims in which the aqueous liquid is water.
5. A method for producing a dispersion of fuel oil and an aqueous liquid suitable for use in a burner comprises passing a liquid fuel and a aqueous liquid into respective inlets of a mixer whereby a heterogeneous phase of the liquid fuel dispersed in the aqueous liquid is produced in the form of droplets.
6. A method according to claim 5 in which the temperature is less than or equal to 1 80 C.
7. A method according to claim 5 or claim 6 in which the aqueous liquid is water.
8. A method according to any of claims 5 to 7 in which the liquid fuel/aqueous liquid compositions are in the range 70/30 to 90/10 by volume.
9. A method according to claim 8 in which the liquid fuel/aqueous liquid compositions are in the range 75/25 to 85/15 by volume.
10. A method according to any of claims 5 to 9 in which the aqueous liquid is blended with a surfactant.
11. A method according to claim 10 in which the surfactant is a non ionic surfactant.
12. A method according to claim 11 in which the surfactant is a none phenol ethoxylate.
13. A method according to any of claims 5 to 12 in which the surfactant concentration is in the range 0.01 to 1.0% based on liquid fuel by volume.
14. A method according to any of claims 10 to 13 in which the surfactant concentration is in the range 0.06 to 0.2% based on liquid fuel by volume.
15. A method according to any of claims 5 to 14 in which the dispersion has a droplet size of greater than 1 micron diameter.
16. A method for producing a dispersion of fuel oil and an aqueous liquid suitable for use in a burner as hereinbefore described and with reference to figures 1 to 4 of the accompanying drawings.
17. A burner system substantially as hereinbefore described and with reference to figures 1 to 4 of the accompanying drawings.
18. Dispersions whenever produced by a method according to any of claims 5 to 16.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9324648A GB2285227B (en) | 1993-12-01 | 1993-12-01 | Burner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9324648A GB2285227B (en) | 1993-12-01 | 1993-12-01 | Burner |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9324648D0 GB9324648D0 (en) | 1994-01-19 |
| GB2285227A true GB2285227A (en) | 1995-07-05 |
| GB2285227B GB2285227B (en) | 1997-03-12 |
Family
ID=10745952
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9324648A Expired - Lifetime GB2285227B (en) | 1993-12-01 | 1993-12-01 | Burner |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2285227B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004081152A1 (en) * | 2003-03-14 | 2004-09-23 | Bp Oil International Limited | Fuel emulsions and methods of manufacture |
| FR2915557A1 (en) * | 2007-04-30 | 2008-10-31 | Bussy Jacques Marie Yves De | Reactor, has enclosure lined with insulating coating and refractory containing combustion chamber and heat exchanger, where enclosure has single outlet taken by coolant gas flow discharging to operating pressure established at exhaust |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3934969A (en) * | 1973-12-22 | 1976-01-27 | Kawasaki Jukogyo Kabushiki Kaisha | Method for burning emulsion oils |
| US4293230A (en) * | 1978-04-12 | 1981-10-06 | Tan Lu J | Apparatus for providing fuel for an oil burner |
| US4430054A (en) * | 1980-12-20 | 1984-02-07 | Nihon Eikan Shido Center Co., Ltd. | Oil-water mixing and supplying system |
| US4696638A (en) * | 1986-07-07 | 1987-09-29 | Denherder Marvin J | Oil fuel combustion |
-
1993
- 1993-12-01 GB GB9324648A patent/GB2285227B/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3934969A (en) * | 1973-12-22 | 1976-01-27 | Kawasaki Jukogyo Kabushiki Kaisha | Method for burning emulsion oils |
| US4293230A (en) * | 1978-04-12 | 1981-10-06 | Tan Lu J | Apparatus for providing fuel for an oil burner |
| US4430054A (en) * | 1980-12-20 | 1984-02-07 | Nihon Eikan Shido Center Co., Ltd. | Oil-water mixing and supplying system |
| US4696638A (en) * | 1986-07-07 | 1987-09-29 | Denherder Marvin J | Oil fuel combustion |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004081152A1 (en) * | 2003-03-14 | 2004-09-23 | Bp Oil International Limited | Fuel emulsions and methods of manufacture |
| FR2915557A1 (en) * | 2007-04-30 | 2008-10-31 | Bussy Jacques Marie Yves De | Reactor, has enclosure lined with insulating coating and refractory containing combustion chamber and heat exchanger, where enclosure has single outlet taken by coolant gas flow discharging to operating pressure established at exhaust |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2285227B (en) | 1997-03-12 |
| GB9324648D0 (en) | 1994-01-19 |
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