OPEN CORE DOWN DRAFT GASIFICATION OF SHREDDED COTTON STALK AND ITS BIOCHAR APPLICATION FOR SOIL AMENDMENT
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Date
2019-07
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jau.junagadh
Abstract
Biomass gasification is a thermo-chemical process, which converts the solid biomass in oxygen deficient environment into combustible producer gas. The cotton stalk is abundantly available for converting solid biomass into useful form of energy, gasification is receiving prime importance. Downdraft gasifiers have promising potential for agriculture and agro industrial applications, which provided improved gas quality, particularly in terms of tar and particulate matter contents of the gas.
In the present study, an open core throat less downdraft gasifier has been consider for study. The performance of the gasifier is made by using shredded cotton stalk as feed stalk. The fuel properties of cotton stalk and its gasification for open core throat less downdraft gasifier were investigated. The whole cotton stalk is converted into shredded material with the help of cotton stalk shredder. The capacity of cotton stalk shredder machine is 220 kg/hr.
The proximate analysis of the shredded cotton stalk in terms of moisture content (11.46 %, db), volatile matter (78.12 %, db), ash content (5.41 %, db), fixed carbon (16.47 %) and bulk density of shredded cotton stalk biomass (146.58 kg/m3) were determined. The values of pH, EC, O.C., available N, P2O5, K2O and S of shredded cotton stalk were found as 5.41, 3.05 dS/m, 54.58 %, 0.77 %, 0.10 %, 0.39 % and 0.11 % ,respectively.
The developed of open core throat less downdraft biomass gasifier reactor was designed for 80 MJ/h thermal capacities, by considering shredded cotton stalk as a feed stalk. The designed parameters of fuel consumption, quantity of gas produced, volume of reactor, area required, diameter and height of reactor was found as 7.5 kg/h, 21.20 m3/h, 0.046 m3, 0.0395 m2, 0.0225 m and 1.5 m ,respectively.
OPEN CORE DOWN DRAFT GASIFICATION OF SHREDDED COTTON STALK AND ITS BIOCHAR APPLICATION FOR SOIL AMENDMENT AAAMENAMENDMENT
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Performance of the gasifier was carried out at four different levels of gas flow rate (18, 20, 22 and 24 m3 / h). The performance parameters like fuel consumption rates (FCR), specific gasification rates (SGR), specific gas production rate (SGPR), equivalence ratio (ER), calorific value of producer gas, gasification efficiency, temperature measurement, amount of residual char and amount of condensed liquid tar production were carried out at all the four levels of gas flow rates in the present study. The distinctive feature of the gasifier is that it can operate successfully by using shredded cotton stalk with producer gas. The gasifier performed best at an equivalence ratio of 0.32, gasification efficiency of 75.59 %, specific gasification rate of 192.32 kg /m2 h, specific gas production rate of 554.16 m3/h m2 with gas flow rate of 22 m3/h. The fuel consumption rate, calorific value, residual char and condensed liquid were observed as 7.64 kg/h, 1087.33 kcal / m3, 24.91 % and 20.30% at the gas flow rate of 22 m3/h respectively. From the results obtained, shredded cotton stalks were successfully used as feed stalk in the developed gasifier.
The economic analysis of the developed gasifier system was considered for thermal application. The economic analysis of the developed system was carried out by considering the shredded cotton stalk. The economic evaluation of the developed gasifier system was carried out by considering the cost of cotton stalk as 1.0 ₹/kg and 1.5 ₹/kg. The cost analysis of the gasifier system was carried out for 270, 300, 330 days of operation per year and at different operating hours per day i,e 14, 16, 18 and 20 hr. The economics of the gasifier system was evaluated at different experimental gas flow rates of 18, 20, 22 and 24 m3/h.
The benefit cost ratio at the highest level of performance of the gasifier system, even at maximum cost of cotton stalk (1.5 ₹/kg) was increased from1.50 to 1.69, 1.51 to 1.55 and 1.52 to 1.56 during 14 to 20 hours of operation per day for 270, 300 and 330 days of operation per year respectively. The payback period at the highest level of performance of the gasifier system even at maximum cost of cotton stalk (1.5 ₹/kg) was decreased from 5y6m7d to 4y9m1d, 5y6m0d to 5y3m8d and 5y5m3d to 5y3m4d during 14 to 20 hours of operation per day for 270, 300 and 330 days of operation per year ,respectively.
It can be safely recommended that the biomass gasification is more economical by considering shredded cotton stalk as feed stalk.
The maximum value of gasification efficiency founded at 22 m3/h thus the values of pH, EC, O.C., available N, P2O5, K2O, S and CEC of biochar were found as 10.35,
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9.90 dS/m, 2.85 %, 0.0014 %, 0.015013 %, 1.284 % , 0.047 % and 48.00 me/100gm respectively.
Crop parameters like number of tillers per plant (1.87), spike length(7.61 cm), number of grain per spike (32.70), weight of grains per plant (2.13 gm plant-1), biological yield (10.63 gm plant-1 ) and plant height (45.14 cm) significantly increase with S2 (WRS) soil at harvest. Significantly, a number of tillers per plant (2.18), spike length (9.04 cm), number of grain per spike (35.13), weight of grains per plant (2.87 gm plant-1), biological yield (18.53 gm plant-1), harvesting index (43.20) and plant height (52.99 cm) were achieved under BP2 soil conditioner level at harvest. Interaction effect between soil type and soil conditioner was found significantly in respect of plant height (55.53 cm) at harvest as compare to control.
Among the different soil conditioner treatments applied, it was founded that soil moisture gradually increases in case of biochar powder, biochar and cotton stalks respectively, as compare to control.
Soil pH was improve by adding biochar powder, biochar and cotton stalks respectively. Biochar additions increased the soil EC, O.C., available N, available P2O5, available K2O, available S and CEC compare to control.
Among the all levels of treatment, BP2 (biochar powder 20 %) is shown best results in crop productivity and soil fertility for all three soil