RICE HULL AND COFFEE BEAN HUSK GASIFIER STOVES
RICE HULL AND COFFEE BEAN HUSK GASIFIER STOVES A TOP-LIT, UPDRAFT, BATCH DESIGN AN ALEXIS BELONIO CONCEPT BY DR. PAUL OLIVIER AND TODD HYMAN
Air Pollution When we think of air pollution in Vietnam, we normally think of outdoor air pollution in heavily populated urban areas. However some of the worst air pollution occurs indoors in rural areas. The burning of biomass such as wood, coconut coir and other crop residues as a source of fuel generates smoke, particulates, carbon monoxide, methane and hundreds of organic compounds including many carcinogens. As a result, thousands of people in Vietnam die each year. Technologies for Vietnam 2
“Turning Carbon Into Cash” “According to World Health Organization estimates, more people in the developing world die each year from conditions related to indoor air pollution—mostly from inefficient, solid-wood-burning stoves—than tuberculosis or malaria. ” http: //www. newsweek. com/id/226941/page/1 Technologies for Vietnam 3
Cook Stove Pollution Indoor cook stoves cause two million deaths per year in India alone. Also the soot from cook stoves has even been linked in a major way to the faster-than-expected rate of global warming and glacial melting. One might argue that many people cannot afford kerosene, LPG or propane, and that little can be done to stop the burning of low-grade biomass fuels. Technologies for Vietnam 4
Gasifying Biomass Ultimately the answer does not lie in abandoning lowcost biomass fuels, but in extracting from them a gas that burns as cleanly as propane or any other fossil fuel. Perhaps there is no fuel that burns as poorly and generates so much smoke as rice hulls, and yet Alexis Belonio, an agricultural engineer from the Philippines, did what all the experts said could not be done. * http: //www. scidev. net/en/agriculture-and-environment/air-pollution/opinions/put-an-end-to-indias-cookingstove-pollution. html Technologies for Vietnam 5
Alexis Belonio Professor Belonio was able to produce from this difficult material a gas that is free of tar, a gas that produces a distinctly blue flame, and consequently a gas that produces no smoke, no particulates and no carcinogens. For this he won in 2008 the prestigious Rolex Award for Enterprise. His invention will have a great impact throughout Vietnam. Technologies for Vietnam 6
The Value of his Invention One ton of rice husks has the same energy as 378 liters of kerosene or 415 liters of petrol, easily supplying the fuel needs of a Vietnamese household for up to a year. The same gas could be used in larger commercial operations: e. g. roasting coffee beans, preparing fresh noodles, cooking pho and so forth. The highland areas of Vietnam produce a lot of coffee bean husks, and this waste can also be processed in the Belonio gasifier, as our trials have demonstrated. Technologies for Vietnam 7
Coffee Bean Husks Technologies for Vietnam 8
Coffee Bean Husks in Reactor Technologies for Vietnam 9
Gasifier Design Therefore with the help of Alexis Belonio, we will soon begin fabricating in Dalat top-lit updraft batch gasifiers for the gasification of rice and coffee bean husks. In all of these designs, air is blown in at the bottom underneath the grate, and gas exits at the top. A fan or blower supplies air to the reactor, and the speed of this fan is controlled by a rheostat. Technologies for Vietnam 10
First Cook Stove The following pictures show the first prototype stove in full operation. It produces a bluish flame that is barely visible. Since then, many improvements have been made. Technologies for Vietnam 11
The First Cook Stove This picture was taken when the stove was in full operation. The hot flame from this stove is barely visible under normal lighting. Technologies for Vietnam 12
First Cook Stove Technologies for Vietnam 13
The First Cook Stove Technologies for Vietnam 14
Three Models Three models of stoves are foreseen: 1. model 150 = 2 kg to 4 kg of biomass per hour 2. model 250 = 5 to 10 kg of biomass per hour 3. model 500 = 20 to 40 kg of biomass per hour Technologies for Vietnam 15
Operating the Stove In operating the stop, ones removes the burner and fills the reactor with hulls. The hulls are lit, and the burner is put back in place. It take about 15 seconds for the stove to be fully operational, and over 45 minutes to gasify all of the hulls in the reactor. Generally this is enough time to cook a meal. This quantity of hulls costs in Vietnam about 210 VND or about 1. 1 cents of a US dollar. Thus we have an affordable fuel that produces no pollution or health problems. The following drawings depict a new design of the 150 mm cook stove. Technologies for Vietnam 16
150 Reactor OD is 150 mm, and the reactor height is 700 mm. The reactor is nothing more than a stainless steel tube with a grate at the bottom. Technologies for Vietnam 17
150 Housing OD = 200 mm The reactor protrudes upward from the housing by 25 mm. Technologies for Vietnam 18
Radiant Barrier The reactor, operating at 1000 C, emits a lot of radiant energy. When this radiant energy strikes the housing made in ordinary stainless steel, the housing absorbs this radiant energy and becomes quite hot. Inserting insulation between the reactor and the housing has little effect. Therefore the best procedure is to attach a thin layer of stainless steel of a low emissivity to the housing and to keep it well polished. In this way over 90% of the radiant energy from the reactor can be returned to the reactor. Technologies for Vietnam 19
Flange Technologies for Vietnam 20
Fan An 80 x 38 mm DC fan (depicted in black) delivers air underneath the grate. The cost to operate this fan for one hour is about 23 VND or $0. 0012 USD. Technologies for Vietnam The bottom of the reactor is a bit higher than the top of the fan. bottom of reactor 21
Powerful Fan This fan is powerful enough to handle most types of un-densified biomass such as rice hulls, coffee bean husks, sawdust, coconut fiber, the shells of various nuts and so forth. Mounted near this fan and on the gasifier itself will be a small battery pack. There will be a rheostat to control fan speed, and this rheostat will operate by remote control. In this way there will be no wires connected to the gasifier. This will make it much easier to empty and reload the gasifier. Technologies for Vietnam 22
Grate The air from the fan comes in below the reactor. This gives unimpeded air flow and no blow-back. Technologies for Vietnam 24
Solids Evacuation Pipe For the easy evacuation of any solids that might fall through the grate. Technologies for Vietnam 25
Base Plate Technologies for Vietnam 26
Burner Fabrication cost = $44. 05 or 837, 000 VND, all in stainless steel. Capacity = 2 to 4 kg’s per hour. This unit weighs less than 9 kg’s. Technologies for Vietnam 27
Heat Recovery The use of a radiant barrier does not keep the housing sufficiently cool. Therefore air must be circulated between the reactor and the housing. This air exits at the top of the gasifier via two horizontal pipes. These pipes are equipped with butterfly valves. In spite of the fact that both butterfly valves can be fully open, the fan is powerful enough to supply whatever air the reactor might need. A simple turn of the rheostat is all that is needed. Technologies for Vietnam 28
Heat Recovery The hot air from these two horizontal pipes can be directed to stove grates. There is enough heat here, for example, to fry an egg or to finish cooking a pot of rice after it was brought to a boil. The following drawings depict a stove top with three grates. The main middle grate is powered by the combustion of syn gas, and the two grates on each side are powered by hot air from the housing. The butterfly valves within the horizontal pipes control the distribution of air to the two warmer grates. Technologies for Vietnam 29
Stove Top rmer a W rner u B er Warm Rheostat Fabrication cost = $33. 55 USD or 640, 000 VND. Technologies for Vietnam 30
Stove Top Technologies for Vietnam 31
Underside of Stove Top Technologies for Vietnam 32
A Simpler Stove Top Design Technologies for Vietnam 33
Lighting a Gasifier Warmer Burner Warmer Technologies for Vietnam 34
Gasifier below Stove Top Note blue flame Technologies for Vietnam 35
Movie Clip Blue Flame Click on picture to play movie clip. Technologies for Vietnam 36
The 250 Stove The 250 mm diameter gasifier follows the same logic as the previous stove. The same 80 x 38 mm fan used in the 150 stove is also be used in the 250 stove. The 250 stove can gasify from 5 to 10 kg’s of rice hulls per hour. The fabrication cost of the 250 stove (all in stainless steel) is $78. 76 USD or 1, 500, 000 VND. This gasifier could supply heat to very large pots. Here a stove top becomes an essential element in providing stability. Technologies for Vietnam 37
The 250 Stove Weight = 12 kg’s. Fabrication cost = $78. 76 Capacity = 5 to 10 kg/hour Technologies for Vietnam 38
The 500 Gasifier The 500 gasifier (supplied with 3 fans) can gasify from 20 to 40 kg’s of rice hulls per hour. This gasifier is too heavy to lift and turn upside down. Here the char is evacuated pneumatically by means of the same three fans. The char is released from the reactor by means of a butterfly grate. Four or five of these units can be operated simultaneously to supply large quantities of heat. Technologies for Vietnam 39
The Importance of a Stove Top A stove top can support pots and pans of all dimensions. In this way one can move, empty, load and light a stove without touching the large pot above it. In this concept, there is no loss of heat associated with remote burners. Each gasifer has one burner, and if more burners are required, more gasifiers are incorporated into a stove top. Technologies for Vietnam 40
Flexibility The amount of biomass in a reactor can be adjusted to match the amount of time that a reactor must deliver gas. If continuous runs over several hours are required, two gasifiers can be rotated under the same pot. It could even happen that several gasifiers could be operated at the same time under one large pot. Technologies for Vietnam 41
The Value of Biochar Yes, there is labor associated with a batch process, but labor in Vietnam is cheap, and a batch process is exceedingly simple and low-cost. The char produced in the gasification of rice hulls or coffee bean husks has a multiplicity of uses and has a much greater value in general than the original biomass material utilized to produce it (including its delivery to the site). In other words, a high-quality gas can be produced at a negative cost or profit. Each household or small Technologies for Vietnam 42
Syn Gas for Free business operating a stove can sell bio-char and, in so doing, completely offset the cost of gathering or purchasing the biomass it needs. If revenue from carbon credits is added to this strategy, then it is hard to imagine a cheaper form of energy that could be made available to the people of Vietnam. Technologies for Vietnam 43
The Cost of Propane and Butane A 12 kg mixture of propane and butane costs in Vietnam about 270, 000 VND ($14. 21 USD). Some small pho shops consume this amount of gas every three days. Roasting coffee beans and boiling water in the preparation of fresh noodles are two more examples among thousands of commercial activities with a high demand for energy. At the same time huge quantities of biomass are dumped in rivers or uselessly burned, giving rise to horrible levels of pollution. Technologies for Vietnam 44
Air Quality In Dalat The quality of air in Dalat is undermined by the use of dirty and inefficient cook stoves. It is also undermined by the outdoor burning of biomass as a means of disposal. The air throughout Dalat is typically quite dirty: it is filled with dioxins, furans, soot, smoke and other pollutants. Once people understand that most of the biomass that they casually set fire to could be utilized to generate a high quality syn gas, they will be motivated to stop this horrible practice. Technologies for Vietnam 45
The Benefit of Small Gasifiers In many cases a gasifier cook stove, manufactured completely in stainless steel, even with a stove top, can be situated on the marketplace in Vietnam for a lot less money than a propane/butane stove top. An entire industry centered in the buying and selling of biochar could be created. Biochar is commonly used in Dalat in the cultivation of certain flowers such as orchids and lilies. Just as scavengers buy and sell recyclables, they could do the same with biochar. Technologies for Vietnam 46
The Benefit of Small Gasifiers Many industries that could never exist due to the high cost of energy will arise. Farmers will benefit from the production of compost laced with biochar. Pig and fish farmers will be in a position to cook and prepare their own feeds. With the spread of this technology in Vietnam, millions of households and businesses will no longer be reliant on fossil fuels. Energy, feed and fertilizer companies will suffer, as the rest of Vietnam prospers. Technologies for Vietnam 47
Decentralized Power Generation This same gasification technology can be used to generate electricity. But before syn gas can be routed to a gen-set, it must be cooled and filtered. The equipment need to cool and filter syn gas is quite inexpensive, and the heat recovered from the cooling of syn gas can be used to produce hot water. The 250 gasifier, for example, can easily power a 10 k. W gen-set. If the principle idea is to produce electricity to charge batteries, then a batch gasifier is all that is needed. Technologies for Vietnam 48
A New Era in Fuel Production The cost of propane and butane in Vietnam will continue to rise. So will the cost of electricity. At the same time Vietnam has millions of tons each year of agricultural and forestry biomass that for the most part are going to waste. This simple gasification technology will allow the people of Vietnam to utilize this waste in the place of fossil fuels and to actually earn money in doing so. We have entered a new era in fuel production and consumption – thanks to this wonderful invention of Alexis Belonio. Technologies for Vietnam 49
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