ECOLOGY - ENVIRONMENT. RE-BIOMAS - Pilot Plant for the Production of Biogas from Biomass

Transcription

1 ECOLOGY - ENVIRONMENT RE-BIOMAS - Pilot Plant for the Production of Biogas from Biomass Indicative photo only - Basic System (Code ) 1. GeneraI The Re-Biomas plant has been specially designed for the study of the anaerobic fermentation process resulting in the formation of methane gas (biogas) from organic waste material (biomass). In the field of the so-called soft technologies, anaerobic fermentation plays a primary role on account of the contribution it can make to the solution of major problems to do both with the energy crisis and with the disposal of organic waste materials. The Re-Biomas pilot plant has been conceived so as to illustrate effectively the functional parameters which determine the quantity and properties of the biogas produced as well as the criteria governing system operation, in particular in terms of safety. Thus, this unit can be viewed as a valuable teaching tool for the understanding of both the processes and the technology adopted in the design of real systems. 2. The anaerobic fermentation process Through the degradation of complex organic molecules, anaerobic fermentation makes it possible to transform organic waste materials (such as solid organic waste, agro-alimentary refuse materials, animal excrements) into valuable materials: a fertilizer and a gas, referred to as biogas, 70% of which consists of methane. Biogas production varies as a function of the nature and quantity of material processed; on average, it comes to ca Nm 3 of biogas per kg of solid matter treated. The average composition of the gaseous product (biogas) is as follows: CH 4 methane (60 70%); CO 2 carbon dioxide (28 32%); H 2 S sulphurised hydrogen, NH 3 ammonia, etc. (2 3%). The lower calorific power of this gas is of about kcal/nm 3 depending on the percentage of methane. The remaining liquid and solid parts are excellent fertilizers for use in farming. The effluent liquid, in hot areas (ambient temperature C) is an excellent basis for the cultivation of aquatic plants which can be used as animal feed. The anaerobic fermentation process is also an effective clean-sing means, with an efficiency, in terms of BOD 6 reduction, of up to 80+85%. DIDACTA Italia S.r.l. - Strada del Cascinotto, 139/ Torino - Italy Tel Fax info@didacta.it

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3 Fig. 1 - General synoptic 1. Feed tank, 200 l capacity with agitator/shredder 2. Reactor of non-toxic plastic material, with capacity of about 100 I W variable power electric heater 4. U manometer to measure operating pressure in the reactor 5. Gas vent valve to adjust operating pressure in the reactor 6. Tank with acid and basic solutions for ph control in the reactor 7. Siphon type discharge for different operating pressures 8. Degasser - settling tank 9. Water absorption column to extract CO 2 from the gas 10. CO 2 removal column with basic solution 11. Silica gel filter drier 12. Column with iron material and active carbon to eliminate H 2 S and other organic compound 13. Gas meter and leak detector with alarm 14. Safety flame trap 15. Low pressure gas storage volumetric tank with safety valve 16. Optional data acquisition system SAD/RE-BIOMAS 17. Reactor of stainless steel, capacity of 40 lit for H 2 production W variable power electric heater 19. Tank with basic solutions for ph control in the H 2 reactor 20. Gas vent valve to adjust operating pressure in the reactor 21. Gas meter and leak detector with alarm P1. Reactors feeding pump P2. Methane reactor recirculating and mixing pump V1 Recirculation and mixing solenoid valve V2 Sludge recirculation valve P3. Methane reactor acid corrective solution feeding pump EV1.Methane reactor acid corrective solution electric control valve P4. Methane reactor basic corrective solution feeding pump EV2.Methane reactor basic corrective solution electric control valve P5. H 2 reactor recirculating and mixing pump P6. H 2 reactor basic corrective solution feeding pump EV3.H 2 reactor basic corrective solution electric control valve LI Level indicators TIC Reactor temperature control thermostat phc ph control system 3. Composition The pilot plant consists of: Basic system (Code ) Optional thermostat-controlled refrigerator for the BOD equipment (Code ) Optional thermo reactor for COD analysis (Code ) Optional kit for the measurement of the concentration of gas (Code ) Optional reactor for hydrogen production by fermentation (Code ) Automatic Data Acquisition System SAD/RE-BIOMAS, consisting of - Electronic transducer and signal conditioning kit (Code ) - Data acquisition and analysis software (Code ) 4. Description Basic system - Code The RE-BIOMAS pilot system is described through the synoptic scheme illustrated in fig. 1. The plant can be fed from a tank (1) fitted out with an agitator/shredder to blend the solid parts. The feed tank can be filled with a solution specially prepared for the tests or with organic waste liquids, sludge, etc. It is also possible to introduce nutritious substances into the tank and/or to vary the ph value before starting the tests. The fermentation process itself begins in a reactor (2) which is fed by means of an electrically operated pump (P1). A programmable timer makes it possible to control the centrifugal pump (P1) and hence to vary reactor feed rate. The reactor (2) has a large see-through window. The waste material stays in the reactor in anaerobic conditions (no oxygen) for a long enough period of time and part of it changes into gas. The fermentation device may work at temperatures higher than ambient temperature thanks to a heater (3). Recirculation and mixing are by means of a pump (P2). The ph level in the tank can be controlled automatically because a ph probe controls the solenoid valves (EV1 and EV2) governing the inflow from the reservoirs containing the corrective solutions (6). The degassing settling tank (8) equipped with siphon type discharge (7) is where the gas is separated from the sludge; the latter can be returned to the fermentation unit to improve process efficiency. At this point, the gas is subjected to a series of treatments: first of all CO 2 is eliminated by a water absorption column(9), then rest of the CO 2 is removed with the aid of a basic solution (10), then the gas is dried by means of a silica gel filter (11) and finally the hydrogen sulphide and other organic compound are eliminated by passing through an iron material bed and an active carbon bed. Finally the product is stored at atmospheric pressure in a volumetric tank (15) after measuring it. The pilot plant can work in different manners, each of which illustrates a different anaerobic fermentation technology. For instance, with a liquid feed, it is possible to obtain: discontinuous operation; continuous operation; operation with sludge recirculation. When the material used is either solid or semi-solid (e.g., high organic nature refuse), the system can be used as a lysimeter for the study of the fermentation process. In this case, the material is fed directly into the reactor (2) and the plant can only work in discontinuous mode.

4 The system is equipped with all the necessary instruments to carry out the tests. In particular, it includes: A ph meter to measure and adjust the ph value in the reactor; 6-location BOD (Biological Oxygen Demand) meter; Imhoff cone for the determination of total solids; U manometer (4) to measure pressure in the reactor (i); U manometer to measure the pressure of the gas in the volumetric tank; No. 6 Pt100 temperature probes connected to a digital indicator to measure the temperature at different points of the system; Produced gas meter; Gas leak detector with alarm. The basic system can be supplemented with several optional instruments or with the Automatic Data Acquisition System. Optional thermostat-controlled refrigerator for the BOD equipment - Code This unit makes it possible to keep the BOD measuring equipment at a constant temperature of 20 C ± 0.5 C during the tests, with ambient temperatures between -10 and +50 C. Optional thermo reactor for COD analysis - Code Designed for 6-location COD (Chemical Oxygen Demand) analysis, this unit is fitted out with a special device to control testing temperature and duration. Optional kit for the measurement of gas concentration - Code This kit makes it possible to take samples and measure the concentration of the following gases: carbon dioxide; methane; hydrogen sulphide. Optional reactor for hydrogen production by fermentation - Code This group is installed between the feeding tank and the methane reactor. It produces Hydrogen from the biomass. Recent studies demonstrate that producing hydrogen and then methane increases of nearly 20% the quantity of energy obtainable from the biomass and the production of CH 4 is increased too. The group is composed of: sealed 40l reactor (17); 1500W variable power electric heater (18); recirculating and mixing pump (P5); basic solution feeding tank with controlled pump for ph control (EV3); produced gas meter (21); No.3 Pt100 temperature probes connected to a digital indicator to measure the temperature at different points of the system; Manometer to measure the reactor pressure (P3). The gas produced is treated in the same way of the CH 4 and then stored at atmospheric pressure with the methane. OPTIONAL SAD/RE-BIOMAS Automatic Data Acquisition System This is used to acquire the data in real time and take full didactic advantage of the gas generation plant. It makes it possible to acquire all the quantities being examined during the tests performed with the manually operated version; furthermore, it is able to produce charts leading to a thorough understanding of the operating principles and system problems of anaerobic fermentation. The system includes: Electronic transducer and signal conditioning kit (Code ) Data acquisition and analysis software (code ) The electronic transducer and signal conditioning kit (Code ) includes the electronic transducers for the acquisition of the following quantities: Pressure n the reactor (P 1); ph value in the reactor (ph); Pressure n gas storage tank (P2); Quantity of gas produced (Q). Page 4

5 Fig. 2 - SAD/RE-BIOMAS software: Working environment Fig. 3 - SAD/RE-BIOMAS software: Real time diagram Furthermore, the electrical equipment conditions and converts the signals originated by six Pt100 temperature probes for the automatic acquisition of the following temperatures: Temperatures in the reactor (T1, T2, T3, T4); Temperatures in the heater (T5, T6). The data acquisition and analysis software (Code ) (see fig. 2 and 3) runs in MS-Windows environment and is used to acquire the data in real time, to process and file them, and to print out on paper or display on screen the characteristic process parameters and diagrams in the different operating conditions. The system can be used with: PC minimum Pentium with HD >10Gb, CD drive, graphic card SVGA minimum, mouse, 32MB RAM, USB port Windows XP or later versions Graphic printer If the hydrogen reactor is present, the data acquisition system will acquire even the data from the hydrogen reactor. 5. Applications The testing procedures consist of the following steps: feeding the system with a specially prepared organic solution (sugar, alcohol, or a solution with lyophilized bacteria) or with solid and/or liquid organic waste materials, setting the operating parameters, and conducting the test up of the production of biogas. By means of the measuring instruments supplied as standard with this system students will find that the quantity and the properties of the biogas produced depend on time of stay in the reactor, temperature and processing methods. The students can also evaluate the quantities of gas produced with different liquid and solid refuse. 6. Reference manual and guide to the exercises The system is supplied with an exhaustive manual which describes the system s technical characteristics, illustrates set-up and utilization procedures, and proposes several exercises to be conducted with the aid of numerical values and reference charts. 7. Required services Three-phase electric power - 50/60 Hz - 4 kw; Water: 1000 l/h - 3 Bar; Compressed air: 50 l/h - 6 Bar. 8. Weights and dimensions Weight when empty: 450 kg - laden weight: 650 kg Dimensions: 2500 x 1800 x 2300 h mm

6 Cod. R00776/E 1110 Ed. 01 Rev. 03 In qualsiasi momento e senza preavviso, la Didacta Italia potrà apportare ai propri prodotti, ferme restando le caratteristiche essenziali descritte, le modifiche che riterrà opportune secondo le esigenze di carattere costruttivo o didattico. Page 6