[Stoves] Pellets in Uganda was Re: Cuber and size of densifying machines.

Mon Mar 17 08:44:39 CDT 2014

Dear Professor Larson, Professor Anderson and Dear List,

Thank you so much for the concern about my PhD application. I have submitted the PhD application to the graduate schools of universities in US including UIUC and I think the decisions will be made within this month. 

As recommended by Prof. Anderson, my CV was attached below including all the projects and experiments I did during master study. And welcome to ask me any questions about my experiments, I would like to reply as long as I can help.

Best wishes

Huangfu Yibo

At 2014-03-16 23:50:09,"Ronal W. Larson" <rongretlarson at comcast.net> wrote:

List, cc Yibo

Yibo is a highly skilled TLUD (for cooking not heating) researcher at one of the major Chinese Universities.  He is looking for a PhD track in a US University.  If anyone knows of an interested faculty sponsor, I can recommend Yibo highly as already knowing a lot in this area.  He has spent considerable time already in the US.

All of the following makes sense - and I am sure Yibo would be willing to answer additional questions.   

Yibo - Thanks for the quick (not at all delayed) response.

Ron

On Mar 16, 2014, at 9:24 AM, Huangfu Yibo <hfyblx at 163.com> wrote:

Dear Professor,

Sorry for the delay...

According to my limited knowledge about the TLUD stove in China, the evaluation of the performance is something related to at least three factors, the stove,the fuel and the user behavior. In China, the factory can produce different size of pellets, 8mm, 15mm and 30mm.

My lab have 8mm diameter pellets (the moisture is about 9%) and the natural draft TLUD stove can achieve CO emission factor 3.53±0.49 g/MJ and PM emission factor 258.15±26.21 mg/MJ with this kind of fuel. The data can be seen in the MC manuscript. TLUD stoves with fan can achieve lower emission with proper air control.

In term of bigger pellets which is produced for heating stove, I never tried before with the stove in my lab because I have not started to test the heating stove yet. But I've seen people using bigger pellets for heating in Liaoning Province. I measured the emission from the chimney and most of the average CO concentrations are between 100-300 ppm (no PM data, unfortunately). The stove they are using is designed with a fan which is only for the secondary air.

I think in the same stove, fuel in smaller size means more gasifying area and more combustible air or VOCs produced during gasification per unit time. With the same air provided, larger size fuel seems burn more slowly than smaller fuel, which may lead to cleaner burning due to enough secondary air feeding. But I just guess...I have never tested one stove using fuel with different size and made of the same biomass.

And of course smaller size fuel light more easily than fuel in larger size if they were made of the same biomass. And good recipe plays important role in the gasification rate.

Best wishes

Huangfu Yibo

At 2014-03-16 13:20:34,"Ronal W. Larson" <rongretlarson at comcast.net> wrote:
Yibo:

 Any comments on this thread?  You may know more than anyone on Chinese pellets, large ones, and TLUDs especially.

Ron

Begin forwarded message:

From: Dean Still <deankstill at gmail.com>

Subject: Re: [Stoves] Pellets in Uganda was Re: Cuber and size of densifying machines.

Date: March 15, 2014 at 8:11:13 PM MDT

To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>

Reply-To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>

Hi Ron,

Pellets made in China are also often smoky and hard to use in a TLUD. The pellet needs to be well made, to a good recipe, to burn cleanly.  Small size seems to be better.

Best,

Dean

On Sat, Mar 15, 2014 at 1:06 PM, Otto Formo <terra-matricula at hotmail.com> wrote:

Dear Ron,
To light a proper Natural Draft Gasifier, you just need a proper starter.

Pellet diped into kerosine will do, or just simple woodshaveings.

The pellet in a Natural Draft gasfier "does not burn" as such, it just turns into (bio)char and only the gases burns about 5 to 10 cm above the biomass .
No need to ingnite the pellet and face the "problems " or challages as for a Rocket stove.

This "brand new" technolgy, known for centuries, compared to the open three stone fire - light from the top to avoid any hassard and hazzel, which will solve most issues conserning smoke and toxic emissions.

Just remember, the more dry and dense fuel, the better...................... 

Otto 

From: rongretlarson at comcast.net
Date: Sat, 15 Mar 2014 13:12:02 -0600
To: stoves at lists.bioenergylists.org
Subject: Re: [Stoves] Pellets in Uganda was Re: Cuber and size of densifying machines.

Dean et al

Was this poor lighting performance in a Rocket or TLUD or other?   Do you (or anyone) think it should make a difference?   And would 1/4” pellets of same density have the same problem?   If not - what is the reason for a size difference?

Anyone using a pellet stove for space heating able to say anything on problems with larger and/or more dense pellets?  Are there warnings on the size of pellets for pellet-type space heaters?

Ron

On Mar 15, 2014, at 11:18 AM, Dean Still <deankstill at gmail.com> wrote:

Hi Paul,

The pellets were about one inch in diameter and very dense. Hard to light and went out easily.

Best,

Dean

On Sat, Mar 15, 2014 at 8:37 AM, Paul Anderson <psanders at ilstu.edu> wrote:

Dean,

Please tell us about those pellets:  characteristics and source and used in what stove(s).    The experience by Awamu in Uganda does not agree with your statement.   But there could be different sources and different stoves.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD  
Email:  psanders at ilstu.edu   
Skype: paultlud      Phone: +1-309-452-7072
Website:  www.drtlud.com
On 3/6/2014 1:20 PM, Dean Still wrote:

Hi Tom,

In Uganda the pellets were too dense and were hard to light. Do you know the density of USA heating stove pellets?

Best,

Dean

On Thu, Mar 6, 2014 at 11:02 AM, Tom Miles <tmiles at trmiles.com> wrote:

Richard,

You probably mean 0.6 g/cm3 (37 lb/ft3) which is very good that’s better than most commercial wood pellets. For reference the dry density of sawdust is often about .160 g/cm3 (or 10 lb/ft3). The loose density of straw is about 0.08 g/cm3 or (5 lb/ft3). The press roll on a pellet mill exerts about 142 bars (2000 psig). If you can get those densities by selecting materials, wetting, pressing at 12 bar and drying you are doing very well.

Tom

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Legacy Found
Sent: Thursday, March 06, 2014 10:46 AM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Cuber and size of densifying machines. (no longer Re: The wood and char and fuel "debate" )

Crispin, what densities are you seeking. We have seen densities of up to  0.6kg/cm^3 by use of really fine granular material charcoal sawdust and certain other ag residues as infiller in hand presses generating only about 12 bars pressure.

I have not attempted pellet production but have no doubt that high pressure is not needed: Rather its more about attention  to blend particle density and size and variations between these (sorting coefficients) that makes the difference density wise. 

May look into it if anybody is interested in the fuel pellet world.

Richard

Sent from my iPhone

On Mar 6, 2014, at 11:38, Crispin Pembert-Pigott <crispinpigott at outlook.com> wrote:

Dear Friends

I agree with Dean on this score. The air flow through the pellets strongly affects the way they burn if the device is constructed such that the fuel contributes a significant element of air control.

These devices

<image002.jpg>

Are ‘cubers’ in that they are producing densified lumps that can be put into a stove. But they will work best in a large stove such as is used in China for space heating and cooking.  The input material is straw and other stover.

The mechanism is an eccentric roller running inside a perforated cage at maybe 60-100 RPM. As Tom notes, power consumption is about 110 kW.

So far I don’t think the product is economically viable as there is a subsidy involved. What we need is a breakthrough technology that will make densified fuel without the need for heat.

Regards

Crispin

Hi Paul,

I have seen the very small pellets sold for heating stoves in the US burn very cleanly. Larger sized pellets did not burn as cleanly. 

Best,

Dean

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