[Stoves] Three fuel combustion/pyrolysis papers

Sat May 20 14:40:18 CDT 2017

Darpan and list:

	See inserts below.

> On May 20, 2017, at 11:29 AM, Darpan Das <darpandasiitb at gmail.com> wrote:
> 
> Dear Mr Larson
> 
> Thanks for sharing the research papers. What is unclear to me is the distinction of the flaming and the smoldering phase. How do we know in an practical experiment that the flaming phase is over and is the beginning of the smoldering phase.

	[RWL:   Only in the TLUD designs can we see the differences.  In 3-stone and Rockets, they are mixed together, except perhaps for a short time at the beginning of the combustion.
	Twenty years ago I saw a similar thesis from the University of Colorado which, like these, only looked at a single particle undergoing first pyrolysis and then combustion.  I am sure there are many more, but I sent these because the topic hasn’t been much discussed on this list.

> 
> Mitchell et al., 2016 (The first and second paper shared by you in the trailing mail), in their study found that flaming phase emissions were much higher than in the smoldering phase. CO emissions are also dependent on the combustion phase. So is emission measurement the a criteria to evaluate the distinction of a phase?
	[RWL:  I wouldn’t say that.  The TLUDs are so much superior over Rockets and three-stones for many reasons - for instance excess air control.  These papers simply emphasize that all solid fuel combustion goes through a pyrolysis phase first.  The oxygen can’t reach the resulting solid charcoal to start the second phase until the gasses stop being emitted.  The first two papers are not looking at anything practical - being too small.
> 
> Quoting a paragraph directly from the paper
> Batch combustion in a fixed bed follows three major stages. Ignition occurs first once the surface material of the fuel devolatilises and forms a gaseous flame. Once this flame is established the ‘flaming phase’ takes place characterised by the combustion of volatile products and their decomposition products (secondary pyrolysis products) as luminous diffusion flames. Thirdly the smouldering phase occurs which is characterised by heterogeneous char combustion and limited visible gas phase combustion. Classer et al. [17] have recently identified four combustion phases but in the present work we have used the simpler classification of the two major phases, flaming and smouldering because of the difficulty of distinguishing between the other phases.
	[RWL:  As I said I have not read any of these three carefully - but it would be interesting to hear from anyone on the list who can talk about the Classer reference to a fourth phase.

> 
> Gravimeteric measurements of particulate matter samples at an interval of 5 minute was done during a cooking cycle. Each of the filter paper would then be analyzed for EC-OC . The EC/TC ratio is an indication of the different combustion phases (Mitchell et al., 2016). 
> 
> Atiku et al., 2016 (by th same group from Leeds University) in their study found that the values of the EC/TC ratios for wood logs, torrefied briquettes, coal and smokeless fuel are highly dependent on burning conditions; namely the flaming and smoldering phases. The results of this study suggest that EC and OC emissions from various solid fuels differ substantially in composition and relative proportion. 
> 
> Smoke emissions from the different fuels are also dependent on the phase of combustion. Roden and Bond, 2006 identified that cooking fires exhibited three general combustion phases, which were named as vigorous flaming, gentle flaming, and smoldering.
> 
> a)      Vigorous flaming is characterized by strong flames with a jutting appearance, resulting from rapid de-volatilization from the wood. It occurs shortly after the ignition of added wood.
> b)      Gentle flaming is characterized by smaller flames, lower emission of scattering and absorbing particles, and a gradual decrease in CO2.
> c)      Smoldering, occurs when the flames have extinguished.
> 
> 
> Roden and Bond, 2006 studied the influence of flaming events and found that very dark particles with the optical properties of black particles are emitted during this phase. During the vigorous flaming phase, the emissions of particles are very high, especially dark, light absorbing particles associated with low instantaneous single scatter albedos. CO2 usually peaks toward the end of vigorous flaming. In the gentle flaming phase scattering and absorption coefficients were often similar in magnitude during this phase, indicating that both strongly absorbing and non-absorbing particles were emitted. Carbon monoxide concentration followed either the scattering or absorption coefficient. In the smoldering phase, light scattering increases sharply because flames are not consuming the volatile matter emitted from the wood, which recondenses into particles. Despite the lack of flame to create black carbon, these aerosols still have an absorbing component. CO emissions here are no greater than those of the preceding gentle flaming phase. The decreasing carbon dioxide concentration shows a drop in burning rate.
> 
> So during realtime emission measurement of stove, can we say that to determine which combustion phase we are in, there can be two parameters to define that
> A) EC/OC ratio 
> B) CO/CO2 ratio

	RWL:   Darpan - I am unable to get into your above further (being fully occupied with large scale biochar topics/promotion), but am impressed that you are so active in the topic.  I think these three papers are addressing what happens, but less on why the emission differences happen as they do.  Obviously there are huge differences in the hundreds of chemical compounds that are emitted and combusted at different times for a particular small solid biomass piece.  I will never have the right technical background to answer the “why” question.  Hopefully others on the list can chime in - especially as to how to construct a superior stove.  The experimental evidence I have is that a TLUD that saves out the produced char is of the superior variety.

	Again, thanks for your interest.

Ron

> 
> Regards
> Darpan
> 
> On Sat, May 20, 2017 at 10:26 PM, Ronal W. Larson <rongretlarson at comcast.net <mailto:rongretlarson at comcast.net>> wrote:
> List:
> 
> 1.  This one appeared as a Journal-recommended non-fee paper:
> “The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove"
> 
> E.J.S. Mitchell <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>a <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0005>, A.R. Lea-Langton <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>a <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0005>, J.M. Jones <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>a <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0005>, A. Williams <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>a <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0005>,  <http://www.sciencedirect.com/science/article/pii/S0378382015301843#cr0005>, P. Layden <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>b <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0010>, R. Johnson <http://www.sciencedirect.com/science/article/pii/S0378382015301843#>b <http://www.sciencedirect.com/science/article/pii/S0378382015301843#af0010>
>   <>
> http://www.sciencedirect.com/science/article/pii/S0378382015301843 <http://www.sciencedirect.com/science/article/pii/S0378382015301843>
> 
> 	It fits TLUDs in the sense that a TLUD separates the two distinct types of burning (flaming and smoldering) - and (hopefully if one places the char in soil) one never sees the second type.  I have NOT read this carefully, but looks well done.
> 
> 2.   From a totally different source this one appeared with a similar flavor:
> The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove <https://recommendations.springernature.com/v1255/redirect/004bM9w-ENjUDU5H2pVUL17iSbuwMKVCjjjyi2fmgQy_Pkthsyu_4YHhRbwzsJyH4DdRhtmVrAZLjXdxRWFEfQDZ7apxqf-z_xWLbCeQuOE1XKrSe4w5mShj2OXoLQ6X7ZwyDcbGMDkqA5b23U7MvijGIg6JNq8JxfpopB31uvluETRcg-zUK-uSL5TVVe6_eK-AJAcEbytnI5U_KvJ_IG0KrRfZtESgYqNVVPDAz_9AqAZOxx2qEqXqf_lbxxUCjMaqVGYM8tvfd7HUF4SLLKstjY4CGAG7Tnk7ZcnKR9BmNOWKU8_Laikhewva_0iHJpmS0kJoDE3QitwRJ6O7n1x_qsXHop5oDgDuAXpJQwLLdOjGjv-pC6ZZK4FKf4S0qjpsjnEZn5K9QTF1lMBn_P2H-jUCU1OUxF7PRz96_lFKcHlFBUY4rfJn5EnzX7xvZ2-xzhvlhsIZsNvmC-tJugJLsNaZGLlCohTN-ZBKD16Iv1-JD6PTnXU5aFn8yy-uJuliffCQqwHhP8ml1yV0MXEQoXuou5KuDqpLDYSc3gjXlakHnI-FAMf5K5yoIpI4Tx1ruKQaeR9y-rl0yfmqWRZNWpmTkKQSouI7R_xoOEiWXXyCGuAGzpxE79AsM5rCsNgjklwL98wFV8wAwcycioMAGU9taiN2GtGR9NYnoJv8b4DV1COrk_MN_hKypxYdUQUCXquUghBqxSchWYeYjcce0Q_UzmGdt-ePYETRmsK5lKuGIveNwoiWxebl00q7AarHZtW11aNFVJz02_7-k0_jr4hKhmop3xGUbUpyMekQFeNo-N4210_qmDLmVpCIPvFscyk2t2bNBea7tw6EQBApaoKo21_OwS9MSM1DwQIdQIP-tLlt_4evPMis-HNYrrTe362LYrnFe_Y3iNKeUreMsP8QMB_1qbe-q8RLklBo9Qv1Sr6joVo4uVUc4Wr3ALUX6CAa5QMUMRkXUikRPUAlaNdn43GpGdL7CnQfSfqK3iY3fv-1DRyFKjIM8qtrbHljmYnJ0vTqD1XAWJu781LSSdZni3l0YzVKFva3g3hnmnV1ZUCkZ04Yq_vfAV2T>Mitchell, E.J.S.Johnson, R.
>  <https://recommendations.springernature.com/v1255/redirect/004bM9w-ENjUDU5H2pVUL17iSbuwMKVCjjjyi2fmgQy_Pkthsyu_4YHhRbwzsJyH4DdRhtmVrAZLjXdxRWFEfQDZ7apxqf-z_xWLbCeQuOE1XKrSe4w5mShj2OXoLQ6X7ZwyDcbGMDkqA5b23U7MvijGIg6JNq8JxfpopB31uvluETRcg-zUK-uSL5TVVe6_eK-AJAcEbytnI5U_KvJ_IG0KrRfZtESgYqNVVPDAz_9AqAZOxx2qEqXqf_lbxxUCjMaqVGYM8tvfd7HUF4SLLKstjY4CGAG7Tnk7ZcnKR9BmNOWKU8_Laikhewva_0iHJpmS0kJoDE3QitwRJ6O7n1x_qsXHop5oDgDuAXpJQwLLdOjGjv-pC6ZZK4FKf4S0qjpsjnEZn5K9QTF1lMBn_P2H-jUCU1OUxF7PRz96_lFKcHlFBUY4rfJn5EnzX7xvZ2-xzhvlhsIZsNvmC-tJugJLsNaZGLlCohTN-ZBKD16Iv1-JD6PTnXU5aFn8yy-uJuliffCQqwHhP8ml1yV0MXEQoXuou5KuDqpLDYSc3gjXlakHnI-FAMf5K5yoIpI4Tx1ruKQaeR9y-rl0yfmqWRZNWpmTkKQSouI7R_xoOEiWXXyCGuAGzpxE79AsM5rCsNgjklwL98wFV8wAwcycioMAGU9taiN2GtGR9NYnoJv8b4DV1COrk_MN_hKypxYdUQUCXquUghBqxSchWYeYjcce0Q_UzmGdt-ePYETRmsK5lKuGIveNwoiWxebl00q7AarHZtW11aNFVJz02_7-k0_jr4hKhmop3xGUbUpyMekQFeNo-N4210_qmDLmVpCIPvFscyk2t2bNBea7tw6EQBApaoKo21_OwS9MSM1DwQIdQIP-tLlt_4evPMis-HNYrrTe362LYrnFe_Y3iNKeUreMsP8QMB_1qbe-q8RLklBo9Qv1Sr6joVo4uVUc4Wr3ALUX6CAa5QMUMRkXUikRPUAlaNdn43GpGdL7CnQfSfqK3iY3fv-1DRyFKjIM8qtrbHljmYnJ0vTqD1XAWJu781LSSdZni3l0YzVKFva3g3hnmnV1ZUCkZ04Yq_vfAV2T>Fuel Processing Technology 2016 <https://recommendations.springernature.com/v1255/redirect/004bM9w-ENjUDU5H2pVUL17iSbuwMKVCjjjyi2fmgQy_Pkthsyu_4YHhRbwzsJyH4DdRhtmVrAZLjXdxRWFEfQDZ7apxqf-z_xWLbCeQuOE1XKrSe4w5mShj2OXoLQ6X7ZwyDcbGMDkqA5b23U7MvijGIg6JNq8JxfpopB31uvluETRcg-zUK-uSL5TVVe6_eK-AJAcEbytnI5U_KvJ_IG0KrRfZtESgYqNVVPDAz_9AqAZOxx2qEqXqf_lbxxUCjMaqVGYM8tvfd7HUF4SLLKstjY4CGAG7Tnk7ZcnKR9BmNOWKU8_Laikhewva_0iHJpmS0kJoDE3QitwRJ6O7n1x_qsXHop5oDgDuAXpJQwLLdOjGjv-pC6ZZK4FKf4S0qjpsjnEZn5K9QTF1lMBn_P2H-jUCU1OUxF7PRz96_lFKcHlFBUY4rfJn5EnzX7xvZ2-xzhvlhsIZsNvmC-tJugJLsNaZGLlCohTN-ZBKD16Iv1-JD6PTnXU5aFn8yy-uJuliffCQqwHhP8ml1yV0MXEQoXuou5KuDqpLDYSc3gjXlakHnI-FAMf5K5yoIpI4Tx1ruKQaeR9y-rl0yfmqWRZNWpmTkKQSouI7R_xoOEiWXXyCGuAGzpxE79AsM5rCsNgjklwL98wFV8wAwcycioMAGU9taiN2GtGR9NYnoJv8b4DV1COrk_MN_hKypxYdUQUCXquUghBqxSchWYeYjcce0Q_UzmGdt-ePYETRmsK5lKuGIveNwoiWxebl00q7AarHZtW11aNFVJz02_7-k0_jr4hKhmop3xGUbUpyMekQFeNo-N4210_qmDLmVpCIPvFscyk2t2bNBea7tw6EQBApaoKo21_OwS9MSM1DwQIdQIP-tLlt_4evPMis-HNYrrTe362LYrnFe_Y3iNKeUreMsP8QMB_1qbe-q8RLklBo9Qv1Sr6joVo4uVUc4Wr3ALUX6CAa5QMUMRkXUikRPUAlaNdn43GpGdL7CnQfSfqK3iY3fv-1DRyFKjIM8qtrbHljmYnJ0vTqD1XAWJu781LSSdZni3l0YzVKFva3g3hnmnV1ZUCkZ04Yq_vfAV2T> 
>  (only free at this single site)
> http://eprints.whiterose.ac.uk/85463/1/A%20study%20of%20soot%20formation%20from%20biomass%20combustion.pdf <http://eprints.whiterose.ac.uk/85463/1/A%20study%20of%20soot%20formation%20from%20biomass%20combustion.pdf>
> 	(again - I haven’t read carefully - but has the same breakout into two types of combustion (Flaming and smoldering)
> 
> 
> 3.  And this one was also recommended at the same place.  We have discussed Dr. Tryner’s thesis work before, but I’m not sure this particular article.   I like it very much:
> 
> The effects of fuel type and stove design on emissions and efficiency of natural-draft semi-gasifier biomass cookstoves
> Tryner, Jessica…Marchese, Anthony J.
> Energy for Sustainable Development 2014
>  <https://recommendations.springernature.com/v1255/redirect/004bM9w-ENjUDU5H2pVULzvM3jlkn27KyMViPvscv-hi-CXyEoj-tptLg8NkrJ1ARoTdXKWTMElsXB1g-CiQnPzRdUXhoi-9SXKcJZRxYxIoGbZ3R9Q0GFRfs7kUT4TRf3hobROqIJ1mZFrTAXhPSBWWkDBVbduwXW-wC_BiP7iSLZZSBFkdrLfVRHTwKNYDmzp-qlZTEDMdCoBiBL2IlG47Z_bx8JNhY3Lmp25m0ReBiRO4vNBeaSgGGC4n1gX5IeaoIjiZtMwD6E9ATUliZFop4OK3VtiHKklUJpakxsawLW_DRz63VFwfpJo7zPsFTatV3lOgsbpA6Hd1QA9S05l-DsPcEuDpcJKwW0yb8pJj64wpr4GLpkmQYP-CDT9ed42HyqXRTfL7eBQhuPet1r-Y2p1qeWgAMLkkAsriGDlt3aHy2EN34JhCH5cRePyXU5zNcFsX7eF0JEFaZ_pRCzjuyseIco7qB8btUpm3N1jk7c3Cxs6JP8HDYSot73vQDYLoMzdEJG33n4Al1QUQS0tRPMEuhcHEeK7CJHF7LvpKRKIHbXX07AyUqP157ogTOvKZ6cyF-HhVayouHRBsbO3hAsWaG4eurQVGl_DDyV5G0ibhYREeLdjSaj2-z75GwgE-4gMNO4NULwQaGsmi1SAuEvCIpIX6VaCMrtVR84edvETSkP4ZP9PPFAp47IKN8FxiYYe4LQaX_87KGz8aVv1-WRtHqBZN3H-gWW9r94efROJ6rVhhHbxW_GnP6zFs6E9jefYGFOPNZeMBLnKITgQ7YZPx4UW7VMWhQpTWSjt5J3lwHS-AE0dlvpU8beaTa5xqywUi4g1j9_Hgbrd0p6mjYNelB_AGTGVKSg0SoZ0yGzqWNplm1-YqWypfYER0PmyD8lHJMAPG--kJooqkK_YA5FC5AeL0pStS9QCqriJN_zlx0hlfP4NWrQpLPDCV9CK0V6aQOHkYk5dgfZwb5l8LPoeJYMivvfzOWnEW4PStBXnZFMuRNswl_4dxAjUXpTASiKfTgzZjSGtJKsI8KiY4gRTBjEStOoopPWbBEf8%3D> <https://recommendations.springernature.com/v1255/redirect/004bM9w-ENjUDU5H2pVULzvM3jlkn27KyMViPvscv-hi-CXyEoj-tptLg8NkrJ1ARoTdXKWTMElsXB1g-CiQnPzRdUXhoi-9SXKcJZRxYxIoGbZ3R9Q0GFRfs7kUT4TRf3hobROqIJ1mZFrTAXhPSBWWkDBVbduwXW-wC_BiP7iSLZZSBFkdrLfVRHTwKNYDmzp-qlZTEDMdCoBiBL2IlG47Z_bx8JNhY3Lmp25m0ReBiRO4vNBeaSgGGC4n1gX5IeaoIjiZtMwD6E9ATUliZFop4OK3VtiHKklUJpakxsawLW_DRz63VFwfpJo7zPsFTatV3lOgsbpA6Hd1QA9S05l-DsPcEuDpcJKwW0yb8pJj64wpr4GLpkmQYP-CDT9ed42HyqXRTfL7eBQhuPet1r-Y2p1qeWgAMLkkAsriGDlt3aHy2EN34JhCH5cRePyXU5zNcFsX7eF0JEFaZ_pRCzjuyseIco7qB8btUpm3N1jk7c3Cxs6JP8HDYSot73vQDYLoMzdEJG33n4Al1QUQS0tRPMEuhcHEeK7CJHF7LvpKRKIHbXX07AyUqP157ogTOvKZ6cyF-HhVayouHRBsbO3hAsWaG4eurQVGl_DDyV5G0ibhYREeLdjSaj2-z75GwgE-4gMNO4NULwQaGsmi1SAuEvCIpIX6VaCMrtVR84edvETSkP4ZP9PPFAp47IKN8FxiYYe4LQaX_87KGz8aVv1-WRtHqBZN3H-gWW9r94efROJ6rVhhHbxW_GnP6zFs6E9jefYGFOPNZeMBLnKITgQ7YZPx4UW7VMWhQpTWSjt5J3lwHS-AE0dlvpU8beaTa5xqywUi4g1j9_Hgbrd0p6mjYNelB_AGTGVKSg0SoZ0yGzqWNplm1-YqWypfYER0PmyD8lHJMAPG--kJooqkK_YA5FC5AeL0pStS9QCqriJN_zlx0hlfP4NWrQpLPDCV9CK0V6aQOHkYk5dgfZwb5l8LPoeJYMivvfzOWnEW4PStBXnZFMuRNswl_4dxAjUXpTASiKfTgzZjSGtJKsI8KiY4gRTBjEStOoopPWbBEf8%3D>http://envirofit.org/wp-content/uploads/2016/06/2015-The-effect-of-fuel-type-etc_Tryner.pdf <http://envirofit.org/wp-content/uploads/2016/06/2015-The-effect-of-fuel-type-etc_Tryner.pdf>
> 
> 	A phrase in the abstract surprised me - that 60% of the energy can remain in the char.  I have never seen the remaining char this high - which should improve the economics if/when one is able to sell the char.
> 
> Ron
> 
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> 
> 
> -- 
> Darpan Das
> Research Scholar
> IIT Bombay
> India
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