Development of De-Oiled Cashew Nut Shell as Fuel Briquettes

Abstract

Converting the de-oiled cashew nut shell into usable products (e.g. briquettes) will address the problem of waste disposal. The study was conducted to develop an environment-friendly fuel briquette sufficient to resist impact during handling and transport and produce the required heat for domestic cooking and also for industrial application. Piston-type and screw-type briquetting machines and three levels of binding agent were used in the production of de-oiled spent cashew shell-based fuel briquettes. The produced briquettes were subject for physicochemical, mechanical and thermal properties tests. Results showed that the best formulation that is required to produce a good quality de-oiled cashew nut shell fuel briquettes using both piston-type and screw type briquetting machines is 10 % binding agent with briquette density, shatter resistance and compressive strength of 0.87 g/cm 3 and 0.83 g/cm 3 , 99.54 and 99.89 % and 43.97 and 101.82 kPa, respectively. The total electricity consumption is 150.91 kWh per ton of briquettes while LPG consumption is 1.32 kg. It is concluded that the energy values and combustion qualities of the briquettes produced in this study are sufficient enough to produce the required heat for domestic cooking and a potential for industrial application.

Comprehensive Review on Bio-Briquettes Developed from Processed Cashew Nut Shell Wastes

“…On average, these shells are dried under sun between 1 and 4 days; and are very effective in bringing down their moisture content below 10% with minimal energy and cost (Ifa et al, 2020;Kimutai, 2021). Likewise, even de-oiled and solvent treated CNS also report upto 13% of moisture content, and needs to be sun dried for 3 to 5 days in order to reduce it below 7% (Tuates Jr et al, 2020). In fact, even briquettes are also dried in similar manner; and supporting this, Sawekwiharee et al (2015) reported the average weight of the sun dried CNS briquettes, with dimension of 5×4.5 cm as 42.49 g (Sawekwiharee et al, 2015).…”

“…Other works include burning of CNS (1 kg) in muffle furnace at 600 ⁰C for 60 minutes; burning in open air for 75 minutes, followed by closed combustion in absence of oxygen for another 30 minutes (Sawekwiharee et al, 2015), burning in developed prototype kiln (capacity of 5 kg) using direct carbonization at 452.2 ⁰C, and indirect carbonization at 458.8 ⁰C (Sanger et al, 2011). Besides, these shells can also be carbonized in customised metal box, maintained at 250 °C for 3 hours (Sen et al, 2016;Sanger et al, 2011); and a drum type carbonizer operated at 250-350 °C (Tuates Jr et al, 2020). Eventually, carbonizing these wastes into biochar enhances their overall combustion efficiency and eases the briquetting process (Sanger et al, 2011).…”

“…This tree is mainly cultivated for its nuts (cashew seed) which grows at the base of its peduncle or pseudocarp (cashew apple); and are consumed as direct snacks, as an ingredient in cuisines, and are even used as the raw material for producing cashew oil and butter (Mgaya et al, 2019). Apart from this, these nuts (either in roasted or dried form) are used for making pastries, confectionaries, ice creams and chocolates (Tuates Jr et al, 2020); and play a vital role in international and foreign exchanges market in many countries (Rabany et al, 2015;Maia et al, 2000). Presently, many countries are cultivating these exotic nuts, with United States and European Union countries being established well in this market (Mubofu & Mgaya, 2018).…”

“…These thermochemical treatments vaporise the harmful and volatile hydrocarbons responsible for toxic emissions from these shells, thus leaving behind significant amount of bio-char and mild traces of CNSL, depending upon the process adopted (Ifa, 2019;Sanger et al, 2011). Hence, briquetting of these CNS wastes helps in developing cheap source for clean energy compatible for both domestic and industrial applications, and is seen as an effective solution for disposing these wastes in a sustainable manner (Lubwama and Yiga, 2017;Mousa et al, 2019;Tuates Jr et al, 2020).…”

“…Besides, these briquettes report higher calorific values than their raw feedstocks and even other solid fuels, thereby exhibiting better and uniform combustion, and high boiling efficiencies with low ash content. Interestingly, these solid biofuels have good mechanical properties including low moisture content, high density and durability that make them resistant to impacts and microbial activities allowing them to get transported, handled and stored easily (Sharma et al, 2015;Tuates Jr et al, 2020;Chungcharoen & Srisang, 2020;Kathuria & Grover, 2012).…”