Focus on Biomass Ash

Utilization of biomass with thermal route which is combustion and gasification will be generated ash residue. While the pyrolysis due to work at low temperatures (400-600 C) and without oxygen / air then there is no ash. Minerals contained in the biomass will remain behind in the form of charcoal products in the pyrolysis process. Ash content and ash chemistry greatly affects the utilization of biomass in addition to heating value, particle size and moisture content. In general characterization of ash from biomass is described by Bryers as follows:

1.     High  silica (Si) and potassium (K) ash content  while the calcium (Ca) is low, with low fusion temperature derived from the group of agricultural biomass wastes.

2.     Low silica (Si) and potassium (K) ash content while calcium (Ca) is high, with a high fusion temperature derived from a group of nearly all the woody biomass. Specifications are best for combustion and gasification.

3.     High potassium (K) and phosphorus ash content, with low fusion temperature derived from faecal matter such as poultry and cattle dung.

Biomass Ash Content

The ash content of various types of biomass indicate slagging behavior.  In general, the higher ash content, the greater the tendency of its slagging behavior. But this does not mean that low ash slagging not show the phenomenon.  Operating temperature, ash chemistry and ash content are variables the occurrence of slagging. If conditions favor the slagging will be even greater. Minerals such as SiO2, Na2O and K2O more tendency toward the occurrence of slagging. Usually slagging occurs in biomass with ash content of more than 4% and non-slagging fuel with ash content less than 4%. According to the composition of the melt, fuel-biomass fuels are grouped into severe or moderate slagging.

Biomass Ash Chemistry 

Issues arising from these ashes is clogging the air intake holes or slagging that will reduce the thermal efficiency of the gasification and combustion process related air supply and biomass distribution in the process unit.

Ash Slagging

So before processing the biomass waste, consider and note the ash content and its chemistry so that it can deliver optimum results.

EFB Briquetting For Bioenergy And Other Purposes

Solid waste such as Empty Fruit Bunch-EFB numbers are very abundant in palm oil mills and to this day are generally not processed moreover utilized optimally.  EFB waste is generally just dumped somewhere and left to decompose naturally through biological processes. Some places have used it as mulch or as an organic fertilizer. But compared to the amount produced, processed EFB are few in number and little added value. The biological processes are also running slow so it takes a big investment to process all EFB waste every day when will use the process. Eco-friendly palm oil mills and "zero waste" certainly impossible achieved.

As energy needs continue to increase every time the diversification of energy becomes important and should be done. These shorter process and results can be used immediately would be an option for the EFB waste processing. Desification technology of biomass into briquette is an attractive option to implement. Briquetting is the shortest route to process the EFB commercially. Process variables such as the size of the briquettes, moisture content, particle size, ash content and plant investment looser than pelleting make it the quickest route of the EFB waste processing. While the briquettes usage  is not a massive pellets but also very large needs. A number of companies producing briquettes, and briquettes are used itself to produce electricity by gasification, pyrolysis and direct combustion technology. Gasification, pyrolysis and direct combustion technology also requires the size and shape of certain raw materials to get optimal performance.

Make the sustainable palm oil business from upstream to downstream is the desire of almost all palm oil businessman. When the palm oil plantation land in need of nutrients that can be supplied from the palm plant itself (EFB for example) but when taken out without anything coming into the soil will also interfere with the palm oil plantation soil fertility in the long term. So it need a good strategy to achieve a sustainable palm oil business. Briquetting is basically the biomass densification that will save transport to its user so that when the briquettes EFB if you want to use as compost can also be parsed again with biological processes to put into the ground so that the balance of soil fertility can be maintained.

Carbon Positive, Carbon Carbon Neutral or Negative?

Greenhouse gases from burning fossilfuels have caused the Earth's temperature to rise. Increasing the temperature of the earth or global warming causing numerous disasters due to climate change in a number of places on earth. When greenhouse gases not controlled then the result of damage to the environment of the earth will be more severe. Therefore, efforts were made to reduce greenhouse gases as the cause of environmental problems. In general, there are four common scenarios to prevent the global warming effect of CO2 in the atmosphere gradually, namely:

1.     increasing the efficiency so the fossil fuel consumption decreases,

2.     mix of renewable fuels with fossil fuels so that fossil fuel consumption has also decreased,

3.     substitution of fossil fuels with renewable fuels

4.     and the absorption of CO2 in the atmosphere so that the concentration of greenhouse gases can be reduced.

Here are some basic terms related to the above problems. Based on the origin and the effect that CO2 in the atmosphere then reviewed as follows:

A.    Carbon Positive

Fossil fuel or fuel mines are grouped into Carbon Positive fuel. This is because the burning of this fuel would make gas content in the atmosphere, especially CO2 will increase. Increased CO2 in the atmosphere is the source of global warming issues above.

Carbon Neutral cycle with biomass thermal route

Carbon Neutral Cycle with biomass densificaion (wood pellet) route

B.    Carbon Neutral

When CO2 gas in the atmosphere does not increase due to the generation of energy from an energy source it is said that energy sources Carbon Neutral.  Because it does not add to or reduce the balance of CO2 diatmosfer it is said to be environmentally friendly energy. Renewable energy sources such as biomass, wind, water and sun are Carbon Neutral. Material substitution of fossil fuels with renewable fuels included in the Carbon Neutral scenario.

C.    Carbon Negative

Currently the CO2 content in the atmosphere has exceeded the threshold limit. The latest report says has reached 390 ppm, this would need to be reduced concentration. Various technologies are developed in order to absorb CO2 from the atmosphere. Naturally the tree is able to absorb CO2 from the atmosphere, meaning that the more we plant a tree, the more CO2 diatmosfer reduced. Biochar or agricultural charcoal, the charcoal is used to fertilize the soil by placing it on the ground is a material that can absorb CO2 from the atmosphere as well as soil fertility, because its nutrient content and media for microbial breeding. Technology in the group Carbon Capture and Storage (CSS) is a Carbon Negative technology, although currently still very expensive investment.

Come be part of the solution to perform activities of Carbon Neutral and Carbon Negative, and minimize part of the problem with Carbon Positive activity.

Production Process Wood Pellet From Wood Biomass

These variables have tended to make pelleting more of an “art” than a “science”, though signifi cant strides are being made in the sophistication of this process, bringing these variables under more control.

Find more detail info in presentation here

Biomass Briquette : Piston/Ram Type or Screw Type?

sawdust briquette and its charcoal briquette

The dimensions of briquettes and pellets are distinguished because of its size. Pellet diameter size less than 25 mm, while the briquettes is more than 25 mm. In contrast to wood pellets that have only one kind of shape that is cylindrical, biomassbriquette has a variety of shapes such as cylindrical, hexagonal, and beams. In addition to the commercial side of the biomass briquette production process is based on grouped into two: first, piston / ram type are made with a piston or mechanical press with high pressure, while the screw-type with screw extruder made ​​the biomass experiencing continuous extrusion with the heated die. In the ram / ​​piston press wear of machine contact with the biomass smaller than the screw extruder. Energy consumption for the ram / ​​piston type is also smaller than the screw extruder type. But in terms of quality and production procedures,  screw extruder type superior than superior to the piston press technology. The presence of a hole in the middle of the screw type briquette making more uniform and efficient combustion and also the type briquette can be carbonized into charcoal briquette. Comparison between the two kinds of biomass briquette as in the table below:

ram type sawdust briquette

 

A.    Ram / Piston Press Technology

-Friction between biomass by means of relatively small, so it can be reduced machine wear.

-The moisture content of the raw material should be made less than 12% for the best results.

- Carbonization on the outer layer is not possible, so the briquette is rather fragile.

B.     Screw Extruder Technology

-Continuous output and briquette out with a uniform size.

-The outer layer of briquette is partially carbonized so making it easier ignition and combustion. This layer also protects from moisture surrounding air.

-Middle hole in the briquette help the combustion because the air supply becomes sufficient.

-Machine or equipment operates very soft without any shock load.

- Machine or equipment is also lighter than the ram / ​​piston press in the absence of reciprocating parts and flywheel.

-Machine components and lubricants used in the machine free from dust or contamination of raw materials.

-High energy consumption compared to the ram / ​​piston press.

Converting oil burner furnace with biomass briquette

At this time screw extruder and ram / ​​piston press technology became commercially important. Ram / ​​piston press technology is older than the screw extruder technology, so that more units ram / ​​piston press in operation today. But the development of a screw extruder also fast which is predicted in the next few years the production of biomass briquette screw type also jumped sharply. Resume of applications of biomass briquette screw type can be seen here.

Chlorine Corrosion, Ghost The Feared Powerplant

Superheater pipes corroded by chlorine

There are 3 groups of biomass used as powerplant fuel around the world based on its quality such as calorific value, ash content and ash chemistry.  First, woody biomass includes all woody trees such as eucalyptus, calliandra, gliricidia and so on. The second group is agro-industry wastes such as ricehusk, baggase, coconut shell, palm shell and so on. While in the third group is grasses.

Although in general the biomass has a low concentration of chlorine (except straw) compared with coal, heavy corrosion occurs in a powerplant that use biomass fuel and cause leaks in the pipes of heat exchanger with  less than 10,000 hours of operation. Corrosion of heat transfer apparatus is strongly associated with ash deposits in the pipes. The mechanism of the complex reactions of chlorine corrosion in boiler pipes like this chart:

The mechanism of corrosion chemical reaction of chlorine

Superheater steam pipes are generally not designed to accommodate the chlorine in biomass fuels. Corrosion mechanisms above are quite well understood by designers and users of biomass boilers in Europe, indications are superheater pipes installed in the low temperature gas zone. Another technology that is able to accommodate biomass fuels with high chlorine levels such as agro-industry wastes and grasses are Circulating Fluidised BedCombustion (CFBC). Temperature pulverized coal (PC) boilers which operate at temperatures up to 1500 C 1400 causing severe corrosion in the superheater pipes, while the CFBC operating at lower temperatures ranging from 850C to 900C. 

Fluidized Bed Combustion System Best Match For Agroindustrial Waste Biomass

Fluidized bed combustion (FBC) systems are widely used for power generation. FBC systems can be modified to be circulating FBC (CFBC), where the material is circulated back into the combustion chamber for burning up.  FBC systems are generally limited to a size of less than 300 MW, but there is powerplant  in Lagisza, Poland who designed it to 460 MW and hopes can be scaled up to 600-800 MW in the future. FBC and CFBC system is important because coal power plant that has long operated can be repowered, opening the possibility of cofiring with biomass on a wider scale conditions. The advantages of FBC systems include:  

-Ability to burn fuels with a wide range in moisture content, particle size, and density. And the potential for this type of fuel coal, biomass, tire-derivated-fuel, agricultural residues, and urban wood wastes.

-Heat transfer from combustion  more efficient so that the combustion temperature is lower, which in turn will reduce NOx emissions.

-Lower costs for SO2 capture because limestone can be added directly to the medium fluidization at a lower cost than installing scrubbers after combustion.

Coal power plant to install FBC  the system as part of a retrofit or new plant construction will be very open to the use of biomass (even if without biomass at first). FBC system has many advantages associated with the ability of fuel flexibility. Transport of biomass from feedstock sources to power plants efficiently if compacted (densification) is made to be like pellets. Wood pellets made ​​from woody biomass is increasingly limited its availability unless intensively pursued as create energy plantations, while the agro-industry wastes such as oil palm biomass is widely available and has not been utilized so that the potential for densification as fuel in FBC systems. Aspects of the environment, climate change and globalwarming is  major factors is the use of biomass fuels.

Optimization of Biomass-Coal Cofiring in Coal Fired Powerplant

Biomass-coal cofiring has been commonly performed by a number of coal power plants in Europe and America with a primary motivation for reducing the environmental impact of emissions. Currently the percentage of cofiring biomass with coal is still small on average below 10%. It can also occur due to a limited supply of wood pellets. But in terms of operational cofiring biomass-coal fly ash will reduce significantly. On the other hand, if the percentage of biomass-coal cofiring is added will cause deposits on boiler pipes that will disrupt the process of heat transfer in the furnace causing inefficient use of fuel with one indicated by the high temperature of the fluegas.

There are three techniques commonly used in biomass-coal cofiring:

1.       Mixing of biomass and coal in the fuel handling system (then fed to the boiler).

2.       Setting up a separate biomass with coal, and then inject into the boiler.

3.       Gasification of biomass to produce a gas which is then burned in the boiler directly or using the integrated gasification combined cycle (IGCC) system.Worldwide reported more than 200 coal power plant that has been tested with biomass (IEA 2010).

Several cofiring  options are available on in coal powerplant, among others:

-Cofire with a low percentage of biomass, with a slight modification of the equipment.

-Cofire with a high percentage of biomass, by upgrading equipment.

- Convert/repower individual coal burners to be fired with biomass

- Convert/repower entire coal plants to be fired with biomass

- Cofire with torrefiedwood

Ash content in coal and biomass are generally differ quite large and moreover  ash chemistry are also a lot of different. This is factor that causes a lot or at least a deposit in the boiler pipes. Percentage of cofiring biomass-coal up to 10% is generally acceptable. Optimal percentage that causes minimal boiler tube deposits and significant reduction in fly ash can be searched based on the variable characteristics of coal and biomass are used.

Whether The Wood Biomass is Preferred Than Agro-Industrial Waste For Pellet Production?

Calorific value, ash content and ash chemistry are three important parameters in determining the quality of the pellets. Above three parameters is strongly influenced by the raw material for the production of pellets. High calorific value, low ash content and ash chemistry that is friendly to the boiler pipes are ideal conditions sought by users of pellets. Selection of raw materials for the production of pellets is the key word to achieve the ideal condition.

The demand of wood pellets for export on a largescale that the average over 5000 tons / month require the supply of raw material of sawdust or wood sawmill waste in large quantities. It is difficult to fulfill. Small-scale wood pellet manufacturer with a capacity of less than 1000 tons / month may be a going concern. Supply of raw material this is one of the key factor of business success and sustainability of the wood pellets.

Agro-industry wastes such as empty fruit bunches of palm oil, coffee husk, rice husk, corn cob and so as a potential raw material for pellet. Quantity of raw material of the waste is overflow so that a more reliable supply of raw materials, but the quality is still below the wood biomass feedstock based on the three parameters mentioned above.

An ideal way to get the raw materials of adequate quality and quantity although it takes a longer time is to create energy farms or plantations energy industry. Woody biomass can be produced in a relatively quick time and the amount of supply is guaranteed. Land of Indonesia's vast and fertile because of the many volcanoes and tropical climates because it is at the equator so it is very possible for this.