Hunan Along New Energy Technologies Co., Ltd
can provide a entire solution from waste to energy, scope of equipment supply covers waste pre-treatment, anaerobic fermentation, biogas cleaning, Combined Heat&Power Unit(CHP), Bio-natural Gas making system, biogas flare/boiler and all auxiliary materials, in conjunction with services of process design, equipment selection, installation and operation & maintenance support.
ALONG BIOGAS is also professional in sewage treatment with non-production of biogas, with purpose of cleaning waste water for recycling of process water or being discharged environmental friendly.
General Process Description for each stage of a complete Biogas Project
1.Waste Material and Pre-treatment
Single or mixture of multiple substrates with high content of organic substance can be used for biogas production. Waste materials and by-products are accrued in conjunction with every single manufacturing operation, from
-The food-production industry and the food-processing industry
-Agriculture raw and residual waste, e.g. Strew,semi-rotten vegetable&fruit
-Supermarkets, e.g. spoiled food products
-Breweries (malt spent grains)
-The ethanol industry (mash)
-The biofuel industry, e.g. glycerine
-Purification plants: Sewage sludge
-The animal feed industry
For feedstock in forms of solid or solid-liquid mixture, such as crop stalks, fruit and vegetable waste, food waste, etc., they should be shred to a fine dimension before fed into digester. Involving equipment such as shredders, crushers, beater, grinding system,dissolving devices etc. Kitchen garbage or community waste, due to its complex compositions, special manual or automatic sorting devices are needed.
Separation process occupies a large proportion in the stage of pre-treatment of waste materials, to remove large particles of inorganic suspended solids, debris and the like contained in the waste water. The equipment used are generally like screw-squeezed, spiral centrifugal, rotary mechanical grille, inclined sieving separator. Grease-water separator or horizontal spiral centrifuge to be used for grease separation if waste contains oil.
For waste materials with high consistence of fiber, long impurities and the like, cutting and grinding devices are required for further processing. For example poultry droppings, which contains soft feathers, it’s difficult for primary solid-liquid separation to remove it, a special cutting&grinding system is wanted to solve such problem.
The feedstock should be cleaned, in order to ensure that it is harmless(from the point of view of hygiene) and it’s free of pathogens, to avoid bad affection for microbiological process in digester.
In the heated and air-tight digester, the biomass ferments in conjunction with the production of methane, mixed with other by-product gas, it’s so called biogas. The microbiological process in digester takes place in four stages, hydrolysis - acidification - acetic acid formation - methane formation.
According to the characteristics of TS total solids, SS suspended solids, COD, BOD etc in the waste water, we will choose the best suitable anaerobic fermentation process among the following types:
- CSTR Reactor (Continuous Stirring Tank Reactor). The feedstock to be fed into digester through bottom entrance. Digester is equipped with mechanical agitators, enables waste materials to be in full contact with micro-organisms. The biogas slurry is automatically discharged and the residue is periodically pumped out of digester. Biogas generated is collected in the gas holder at the top of the reactor or flows into the free-standing gas holder on the ground. Proper TS(total solid) content varies in the range 6% to 12%, HRT(hydraulic retention time) varies from 20 to 30 days depending on the actual TS% and reactor temperature.
- USR Reactor (Up-flow Solid Reactor). USR reactor is a simple structure, suitable for sewage with high content of suspended solids. Waste is pumped into digester from bottom of reactor, and contact with activated sludge during up-flowing, so that the biomass to be quickly fermented. Unprocessed biomass solid particles and microorganisms remains inside reactor by natural sedimentation, and the bio-liquid overflows from the upper part of the digestor. Proper TS(total solid) content varies in the range 3% to 5%, HRT(hydraulic retention time) is about 10~15 days.
- UASB Reactor (Up-flow Anaerobic Sludge Blanket). The feedstock enters digester through the water distributor at the bottom of the reactor. Above the water-distributor there is a high concentration, highly active sludge blanket, where most of the organic matter is dissolved and fermented to methane and carbon dioxide. Due to the stirring of water flows and bubbles that full of biogas, there is a floating sludge layer above the sludge blanket. Gas,Liquid and sludge particle Solids are separated automatically through a special three-phases mechanical separator. Biogas flows into the gas storage chamber, sludge particles automatically fall to the sludge blanket, slurry gets out of reactor at clarification chamber. Proper TS(total solid) content is about 1%, HRT(hydraulic retention time) is about 5 days.
- EGSB Reactor (Expanded Granular Sludge Blanket). EGSB is the third generation of anaerobic reactors developed on the basis of UASB. Unlike UASB, EGSB has a dedicated sewage recovery device. The expanded Blanket of granular sludge improves contacting between organic matter and microorganisms in the fluid, enhances the mass transfer effect and improves the biochemical reaction rate of the reactor, thereby greatly improving the efficiency of the reactor treatment. EGSB reactor is always in cylindrical column shape with a high height/diameter ratio, generally up to 3~5,can be up to 15 to 20 meters high. EGSB has high loading ability, the organic loading rate(OLR) is 2~3 times higher than UASB, up to 6 ~ 18mgCOD / m³.d.
- IC Reactor (Internal Circulation). IC is an internal loop type of anaerobic reactor, similar to the series of two UASB tanks, and like EGSB, with a big height/diameter ratio. The biggest difference in operation between IC and UASB is the performance of bearing shock load, IC can automatically dilute the input materials through the internal circulation, effectively ensuring the stability of input fluid concentration in the first reaction chamber. The second advantage is that it only requires a short residence time, suitable for considerable biodegradable sewage with high SS content. IC has a significant advantage over UASB,due to the high flow rate of IC, SS does not accumulate in the reactor, and sludge can maintain high activity.
The material for the above reactors can be enamel steel tank, made of titanium-alloy enamel steel plate, with double-sided enamel coating, beautiful appearance, easy to clean, easy maintenance with good wear resistance, corrosion resistance, impact resistance,insulation performance, anti-static; No special anti-corrosion treatment required, lifetime designed for 30 years at least.
In addition, the above reactors can be also LIPP tanks under unique construction method. Dur