N.K.S. Rajan

Development of producer gas engines

Abstract This paper summarizes the findings involved in the development of producer gas fuelled reciprocating engines over a time frame of six years. The high octane rating, ultra clean, and low-energy density producer gas derived from biomass has been examined. Development efforts are aimed at a fundamental level, wherein the parametric effects of the compression ratio and ignition timing on the power output are studied. These findings are subsequently applied in the adaptation of commercially available gas engines at two different power levels and make. Design of a producer gas carburettor also formed a part of this developmental activity. The successful operations with producer gas fuel have opened possibilities for adapting a commercially available gas engine for large-scale power generation application, albeit with a loss of power to an extent of 20–30 per cent. This loss in power is compensated to a much larger extent by the way toxic emissions are reduced; these technologies generate smaller amounts of toxic gases (low NOx and almost zero SOx), being zero for greenhouse gas (GHG).

Gasifiers and combustors for biomass – technology and field studies

This paper deals with biomass-based energy devices developed in recent times. The need for this renewable energy for use in developing countries is first highlighted. Classification of biomass in terms of woody and powdery (pulverized) follows, along with comparison of its energetics with fossil fuels. The technologies involved, namely gasifier-combustor, gasifier-engine-alternator combinations, for generation of heat and electricity, are discussed for both woody biomass and powdery biomass in some detail. The importance of biomass to obtain high-grade heat through the use of pulverized biomass in cyclone combustors is emphasized. The technoeconomics is discussed to indicate the viability of these devices in the current world situation. The application packages where the devices will fit in and the circumstances favourable for their seeding are brought out. It is inferred that the important limitation for the use of biomass-based technologies stems from the lack of recognition of their true potential.

Gaseous Emissions Using Producer Gas as Fuel in Reciprocating Engines

In the recent times issues like the Green House Gas (GHG) emission reduction and carbon-trading through Clean Development Mechanism (CDM) have gained large prominence as a part of climate change. Biomass gasification is one such technology which is environmentally benign and holds large promise for the future. These technologies are currently being utilized for power generation applications at a number of industrial sites in India and abroad. This paper summarizes the work conducted using biomass derived producer gas in reciprocating internal combustion engines. The producer gas for the experimental work is derived from the well-established open top, re-burn, down draft gasification system, which is proven to generate consistent quality, ultraclean producer gas. This paper discusses the actual emission measurements in terms of NOx and CO on (a) dual–fuel engine (compression ignition engine) – using high speed diesel and producer gas fuel, (b) gas engine (spark ignited engine) – using 100% ultra clean producer gas. In the case of dual-fuel operation it is found that the NOx levels are lower compared to operations with pure diesel fuel on account of lower peak flame temperature, whereas the CO levels were higher due to combustion inefficiencies. In the case of gas alone operation it is found to be environmentally benign in terms of emissions; NOx and CO levels are found to be much lower than most of the existing emissions norms of various countries including the United States and European Union.

Combustion of wooden spheres—Experiments and model analysis

Studies on combustion of wooden spheres have been made towards understanding their role in wood gas generators. Experiments on 0.01, 0.015, 0.02 and 0.025 m dia spheres show two regimes of combustion-flaming and glowing. During flaming combustion, the sphere decreases in diameter by about 10% and loses 75-80% of its weight, this reduction being related to loss of volatiles only. Simulation experiments performed by inert heating of the wooden spheres to temperatures of about

Behavior of methane-oxygen-nitrogen mixtures near flammability limits

350^0C

Single Particle and Packed Bed Combustion in Modern Gasifier Stoves—Density Effects

to cause loss of volatiles confirms the above result. The glowing zone combustion involves the remaining weight loss of 20% and diameter variation following the

Universal Flame Propagation Behavior in Packed Bed of Biomass

d^2

IISc-DASAG biomass gasifiers: Development, technology, experience and economics

-1aw. The mass loss correlations follow mass loss rate (kg/s) = k . diameter (m),

Technology for gasifying pulverised bio-fuels including agricultural residues

k = 7 \times 10^{-4}

Biomass gasification technology - a route to meet energy needs

for flaming zone and