Application of Wood Chip Producer Gas and Bio-diesel Blends In CI Engine

Application of Wood Chip Producer Gas and Bio-diesel Blends In CI Engine

Prof. Shara d P. Bargat DESS COET, Dhamangaon Rly. Amravati-444709(M.S.)INDIA

Prof. Pravin S. Wagh, DESS COET, Dhamangaon Rly. Amravati-400709(M.S.)INDIA

Prof. Uday A. Kakde DESS COET, Dhamangaon Rly. Amravati-444709(M.S.)INDIA

Abstract

In order to meet the energy requirements, there has been growing interest in alternative fuels lik e biodiesels, methyl alcohol, ethyl alcohol, biogas, hydrogen and producer gas to provide a suitable diesel substitute for internal combustion engines

The performance of the CI engine was investigated for Dual Fuel Mode and mixed fuel mode operation in terms of brak e thermal efficiency, specific energy consumption and compared with the base line performance of the engine.

The specific energy consumption is found to be minimum in the tune of 13.8 MJ/k w-hr and the exhaust gas temperature is observed higher in the range of 427oC. The increment in load on the engine increases the brake thermal efficiency, exhaust gas temperature, liquid fuel replacement and lowered the specific energy consumption. The maximum liquid fuel replacement in the tune of 46.73% is possible with the use of mixed fuel

1. Intro ductio n

   Now-a -day alternative fuels have been interesting for everyone in country due to fuel crisis occurred. In order to meet the energy requirements, there has been growing interest in alternative fuels like biodiesels, methyl alcohol, ethyl a lcohol, biogas, hydrogen and producer gas to provide a suitable diesel substitute for internal combustion engines. Gasificat ion is a very efficient method for extracting energy from many diffe rent types of organic materials and also has applications as a clean waste disposal technique. Gasification is a process in which solid bio mass is converted into a mixture of co mbustible gases, which complete their co mbustion in C.I engine. Hence, producer gas can act as a promising alternative fuel,

   especially for diesel engines by substituting considerable a mount of diesel fue ls.

   There are many alternative fuels in India for exa mp le gas fuel, Bio -diesel, and others. One of them is the producer gas acquired from b io-mass such as wastes fro m agricultura l products. Mostly, the producer gas is used as the fuel for the electricity generation system. This system is operated by the dual fuel diesel engine in which the diesel is ma in fuel wh ile producer gas is the secondary fuel. By using the dual fuel system, in this experiment, downdraft gasifier is used to produce the producer gas and wood chips as biomass feedstock for downdraft gasifier [1].

   The producer gas generated through the process of gasification fro m bio -mass such as wastes from agricultural products, wood chips, coconut shells, groundnut shell, etc can be considered as alternative fuel for IC engines. Gasification is a process that converts carbonaceous materials, such biomass into carbon monoxide and hydrogen by reacting the raw materia l at high te mperatures with a controlled a mount of oxygen. The resulting gas mixture is called producer gas and is itself a fuel. Gasification is a very effic ient method for e xtracting energy fro m many different types of organic materia ls, and also has applications as a clean waste disposal technique [2].

   In order to meet the energy requirements, there has been growing interest in alternative fuels like biodiesels, methyl alcohol, ethyl a lcohol, biogas, hydrogen and producer gas to provide a suitable diesel oil substitute for internal co mbustion engines. Vegetable oils present a very promising alternative to diesel oil since they are renewable and have similar properties. Vegetable oils offer a lmost the same power output with slightly lower thermal effic iency when used in diesel engine. Research in this direction with edible oils have yielded encouraging results, but their use as

   fuel for diesel engines has limited applications due to higher domestic require ment[3].

   Internal combustion Engines have proved its utility in transportation, agriculture and power sector of India. These engines also help in developing decentralized systems energy for rural electrification. Ho wever, the concerns about long term availab ility of petroleu m diesel and strict environmental norms have mandated that renewable alternative to diesel fuel should be e xpedite e xplored to overcome these problems. Vegetable oils have always been considered as a good alternative to diesel for last many years and oil derived fro m Jatropha cruces plant has been considered as a sustainable substitute to diesel fuel.

   Co mpression ignition (CI) engine could be operated with fo llo wing fuels either a lone or in the form of mixtu re. Use of diesel in CI engine is a well-proven technology. In India, a large variety of bio mass feedstock is available in huge amounts. As these are available locally, bio mass gasifier-based power generation may be an appropriate option for decentralized power generation in many parts of the country [4]. Bio mass gasifier-based system capable of producing power fro m a fe w kilowatts up to several hundred kilo watts has been successfully developed indigenously. The utilizat ion of producer gas in the diesel engine in dual fuel operation is an established technology for conservation of Diesel. Producer gas could be used in CI engine, without any modification in the engine. However, it cannot replace the diesel complete ly. Diesel replace ments up to 70 90% have been achieved in the dual fuel mode. Because of its poor ignition/delay ignition characteristics some minimu m a mount of Diesel is required to start the ignition. On the other hand, the use of plant oil as fuel for CI engine is not new. The all properties of plant oils were c lose to diesel e xcept viscosity and volatility. Various methods were adopted to overcome these problems. It included blending of oils with diesel, heating of plant oils before injecting into the combustion chamber of engine and esterification of plant oils [2].

2. Overview of producer gas

   What to expect from a wood gasifier system?

   Operation of modern spark ignition or compression ignition stationary engines with gasoline or diesel fuel is generally characterized by high reliability and minor e fforts fro m the operator. Under norma l circu mstances the operator's role is limited to refueling and maintenance. There is little need for action and virtually no risk of getting dirty. Start and operation can in fact be made fu lly auto matic.

   Anybody expecting something similar fo r wood gas operation of engines will be disappointed. Preparation of the system for starting can require half an hour or more . The fuel is bulky and difficult to handle. Frequent feeding of fuel is often required and this limit the time the engine can run unattended. Taking care of residues such as ashes, soot and tarry condensates is time-consuming and dirty.

   It is a co mmon mistake to assume that any type of biomass which fits into the opening of the refueling lid can be used as fuel. Many of the operational difficult ies which face ine xperienced users of gasifiers are caused by the use of unsuitable fuels. In order to avoid bridging in the fuel bunker, reduced power output because of large pressure losses, or "weak" gas, slag cakes, tar in the engine and damage to the gasifier caused by overheating, it is necessary for most designs that the fuel properties are kept within fairly narrow ranges. This is not necessarily a more serious limitation than the need to use gasoline of super grade for high compression spak ignition engines rather than regular gasoline or diesel fuel. But in the case of gasifier operation, more of the responsibility for quality control of the fuel rests with the operator. The need for strict fuel specifications is well documented in the e xperiences reported from the Second World War [2, 5].

   Operation of wood gas engines can also be dangerous if the operator violates the safety rules or neglects the ma intenance of the system. Poisoning accidents, e xplosions and fires have been caused by unsafe designs or careless handling of the equipment. It may be assumed that modern systems are designed according to the best safety standards, but it is still necessary to handle the equipment in a responsible manner [5].

3. Fuelling Of Engines by Pro ducer Gas

   Producer gas, the gas generated when wood, charcoal or coal is gasified with air, consists of some 40 per cent combustible gases, ma inly carbon mono xide, hydrogen and some methane. The rest are non-combustible and consists main ly of nitrogen, carbon dio xide and water vapor.

   The gas also contains condensable tar, ac ids and dust. These impurit ies may lead to operational problems and abnormal engine wea r. The main proble m of gasifier system design is to generate a gas with a high proportion of combustible components and a min imu m of impurities [5].

4. Possibilities of Us ing Producer Gas with Different Types of Engines

   Spark ignit ion engines, normally used with petrol-or kerosene, can be run on producer gas alone. Diesel engines can be converted to full producer gas operation by lowering the compression ratio and the installation of a spark ignition system. Another possibility is to run a normal unconverted diesel engine in a "dual fue l" mode, whereby the engine draws anything between 0 and 90 per cent of its power output from producer gas , the rema ining diesel o il be ing necessary for ignition of the combustible gas/air mixtu re. The advantage of the latter system lies in its flexibility: in case of ma lfunctioning of the gasifier or lac k of bio mass fuel, an immed iate change to full diesel operation is generally possible.

   However, not all types of diesel engines can be converted to the above mode of operation. Co mpression ratios of ante-chamber and turbulence chamber diesel engines are too high for satisfactory dual fuel operation and use of producer gas in those engines leads to knocking caused by too high pressures combined with delayed ignit ion. Direct injection diesel engines have lower co mpression ratios and can generally be successfully converted [5].

5. Theory of Gasification

   The production of producer gas called gasification, is partial combustion of solid fuel (biomass) and takes place at temperatures of about 1000 ºC. The reactor is called a gasifie r. The co mbustion products from complete co mbustion of biomass generally contain nitrogen, water vapor, carbon dioxide and surplus of oxygen. However in gasification where there is a surplus of solid fuel (incomp lete co mbustion) the products of combustion are combustible gases like Carbon monoxide (CO), Hydrogen (H2) and traces of Methane and no useful products like tar and dust. The production of these gases is by reaction of water vapor and carbon dio xide through a glowing layer of charcoal. Thus the key to gasifier design is to create conditions such that a) biomass is reduced to charcoal

   and, b) charcoal is converted at suitable temperature to produce CO and H2.

   Since there is an interaction of air or o xygen and biomass in the gasifie r, they are classified according to the way air or o xygen is introduced in it. There are three types of gasifie rs (Figure II-I); Do wndraft, Updraft and Crossdraft.

   Fig. II-I Sche matic vie w of various types gasifier[5].

   Table II-I show the advantages and disadvantages of diffe rent types of gasifier set up used for generating the producer gas from the woody bio-mass[5].

6. Test methodology

   1. Para meters Se lection:

      The selections of appropriate parameters were essential for engine calculations and set-up available. The ma in para meters desired from the engine are listed below.

      1. Power p roduced by the engines

      2. Specific energy consumption

      3. Bra ke therma l e fficiency

      4. Fuel consumption

      5. Speed of the engine

   2. Para meters Ca lculat ion:

With a view to calculate the parameters mentioned above, it was essential to pick up the follo wing signals fro m the test bench.

1. RPM of the engine

2. Load on engine

3. Fuel consumption rate

4. Producer gas consumption rate

5. Vo ltage generated by the alternator

6. Current generated by the alternator

   Once the parameters we re selected, the essential instruments required for sensing these parameters were installed at the appropriate points in the e xperimental set-up.

   TABLE II-I

   AVANT AGES AND DISADVANTEGES OF DIFFERENT TYPESOF GA SIFIER UNIT

7. Experimental setup

   1. Details of Engine Specificat ion:

      Fie ld Marshal make diesel engine was used. Detailed specification of the engine given in table IV-I:

      TABLE IV-I

      ENGINE SP ECIFICATION

   2. Details of Gasifie r Spec ification:

      A Downdraft wood waste gasifie r, Associated Engineering Work (AEW) ma ke having the technical collaboration with SPRERI was used for generation of producer gas from wood chips as an input feed stock.

      TABLE IV-II GASIFIER SP ECIFICATION

      1. Expe rimental Test Rig:

      The ma in components of the experimental setup are Engine t wo fuel tanks (Diesel and Jatropha blend), Gasifier unit, gas flow meter, fuel consumption measuring unit, Electrica l resistance loading arrangement, volt meter, a mmeter and digital tachometer meter. Fig. IV-I shows the schematic diagra m of the e xperimental setup used for e xperimentation.

      Fig. IV-I Sche matic diagra m of e xpe rimental test rig

      The engine was started with diesel for at least 30 minutes and once the engine warms up, it is switched over to Jatropha biodiesel blend. For switching the engine fro m d iesel to Jatropha biodiesel blend, a two way valve was provided on the control panel. Both the fuels from the two tanks can be feed to the engine through this valve separately. One end of the valve is connected to Jatropha biodiesel blend tank and the other end is connected to diesel. The fuel fro m t he valve enters into the engine through this fuel measuring unit. With the help of this fuel measuring unit, Fig. IV- II shows the schematic layout of the experimental setup.

      Fig. IV-II Layout of e xpe rimental test rig

8. Results:

   The main objective of the work was to fuel the diesel engine with blend of Jatropha bio-diesel and wood chip producer gas and performance was studied on different blending % of Jatropha bio-diesel at different loading condition and compared with baseline data. The engine performance was test on various loads as 1kw, 2kw, 3kw and 4kw. The results of this experiment are presented in brake thermal e fficiency and specific energy consumption.

   1. Bra ke Thermal Effic iency

      The brake therma l efficiency of the engine is one of the most important criteria fo r evaluating the performance of the engine. It indicates the combustion behavior of the engine to a great e xtent.

      Fig. V-I Brake thermal effic iency with brake powe r Figure-V-I shows the variations in brake therma l

      efficiency of the engine for different co mbination of fuel blends. The brake therma l effic iency with diesel + wood chips producer gas was found to be slightly lo wer than that of diesel + B25 + Producer gas in mixed fuel mode fuel at tested load conditions. There was no diffe rence between the diesel + B25 + Producer gas and diesel + producer gas on efficiencies at the lower load but at the higherloading condition the engine give the ma ximu m brake therma l efficiency with diesel + B25 + Producer gas . The brake thermal effic iencies of engine, operating with diesel + B25 + Producer gas in mixed fuel mode were 11.25, 19.03, 23.8 and 26.08 per cent at 1kw, 2kw, 3kw and 4kw load conditions respectively. It was observed that detonation or knocking occurred when the engine was operated with a large fraction of the fuel energy from producer gas particularly at high load. In orde r to reduce detonation, the intake of producer gas was reduced resulting in a low liqu id fuel replace ment at high load.

   2. Specific Energy Consumption

The brake specific energy consumption was preferred to compare the performance of CI engine at diffe rent loading condition for mixture of diesel + producer gas in dual fuel mode and diesel+ blend of Jatropha bio – diesel + Producer gas. Specific energy consumption in dual fuel mode (d iesel and producer gas) was calculated fro m the fue l consumption and calorific value of diesel and producer gas. Figure-V-II shows the variations in specific energy consumption of the engine for different comb ination of fuel in dual fuel mode and in mixed fuel mode.

Fig. V-II Specific Energy Consumption with bra ke power

With increased percentage of Jatropha bio-diesel in the blends, specific energy consumption increased. The decrease in specific energy consumption may be attributed to the more energy content with increased gas flow rate of wood chips producer gas in the combustion chamber. Form the Fig. V-I and Fig. V-II it was observed that, the diesel + B25 + Producer gas in mixed fuel mode shows the better performance than other combination of fuel.

Conclusion

Fro m the e xperimentation on the engine the following conclusions were drawn and the best combination of fuel is found for the min imu m consumption of the diesel.

• In dual fuel mode operation the engine performance decreases, with increased smoke density at all load conditions.

• In the dual fuel mode of operation, while using wood chips, higher liquid fuel savings is achieved at part load conditions.

• The ma ximu m Brake therma l effic iency is observed to be 26.08 % in mixed fuel mode( Diesel+ 25% Jatropha bio-diesel +PG) at higher load

• Specific energy consumption is found to be minimu m in mixed fuel mode in the tune of 13.8 MJ/kw-hr

• It is observed that, the increment in load on the engine increases the BTE and lo wered SEC for the e xisting engine set up.

• The exhaust gas temperature is observed higher in the range of 427oC

• The best combination of fuel found to be Diesel 75 %

  + Jatropha Bio-Diesel 25% + Producer Gas for Constant engine Speed of 1500 RPM. The Bra ke therma l efficiency

• observed 26.08 % Specific Energy Consumption found to be 13.8 MJ/kw-hr

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