5.6 Measuring methods and devices for biogas plants

5.6 Measuring methods and devices for biogas plants

The purpose of conducting measurements on a biogas plant is to enable timely detection of developing problems, adjustment to optimum operating conditions, and gathering of practical 'data for comparison with those of other plants. The following variables can be measured quickly and easily:
- gas production via dry gas meter or by measuring the fill level of the gasholder
- weight of inputs via a hand-held spring scale
- temperature via an ordinary stem thermometer or electronic temperature sensor
- total-solids content by drying a sample at 104 °C and weighing the residue on a precision balance
- H₂S content of the gases via a gas test tube
- pH via litmus paper.
The contents of the substrate/slurry can only be determined by a special laboratory.
Various levels of precision are recommended, depending on the set objective and corresponding time, effort and equipment expenditure.
Observation by the user

Procedure

- measuring the gas consumption through daily checking of the calibration marks on the gasholder
- measuring the daily input quantities via defined-volume vessels
- measuring the air/slurry temperature with a thermometer.
Documentation
Daily notation of measured values.
Interpretation/results
Daily gas production as a function of substrate input and temperature.
Field testing by the extension officer

Procedure

- installation and daily reading of a dry gas meter to determine the rate of gas production
- random sampling of the CO₂ and H₂S contents of the biogas
- determination of quantities added by weighing the moist mass and water on a spring scale
- random sampling to determine the total solids content of the substrate
- measuring the digester temperature with the aid of a remote electronic thermometer
- measuring the ambient temperature with a mini-max thermometer
- determining pH levels via litmus paper
- laboratory testing to determine the C/Nratio, volatile solids content and manurial quality of digested slurry.

Fig. 5.38: Measuring instruments for biogas field tests. 1 Gas meter, 2 CO2 tester, 3 Mini-max thermometer, 4 Spring scale, 5 Stem thermometer, 6 Insertable thermometer, 7 Electric remote thermometer, 8 Litmus paper (Source: OEKOTOP)

Documentation
Daily entry of measured values in a log book.
Interpretation of results
- time history of daily gas production as a function of temperature and substrate input
- time history of specific gas yield (Gy = m³ gas/kg TS) and of specific gas production (m³ gas/m³ Vd) as a function of temperature
- time history of pH
- time history of maximum and minimum ambient temperatures, i.e. mean monthly and annual temperatures, plus extremes.

Balaji Biogas System PDF

Installation of Balaji Biogas System and its Application with Purification and Bottling Biogas Unit


Introduction
At present our country is facing various problems which become more serious in next coming years. Demand of petroleum products is increasing, India has spending a big budget for importing these products and on the other hand our country faces serious problems like environmental pollution, disturbance in weather & global warming. India is an agriculture-based country and there is abundant availability of resources but these are not properly used and commercialized. In spite of all the developments and technologies are available yet the rural people facing the shortage of energy. The prime challenge for the country is to provide the minimum energy services to allow the rural people to achieve decent standard of living. The biogas plant is a boon to the Indian farmers. The two main products of the biogas plants are enriched compost manure and methane where as compost manure helps to meet the fertilizer requirements of the farmers in a more economical and efficient manner and boost agricultural production. Biogas is used for cooking and lighting purposes and in larger plants , as motive power for driving small engines.Indian government have installed gobar gas plants, which are approximately 12,00,000small, 3,40,000 medium, and 4,000 big gobar gas plant. If 20,00 gobar gas plants of 120 M3 hasbeen installed then approximately 6842 Lakh Rs. of diesel/petrol can save, but this project isfailed in few years no body have think that why this project is failed.Few years back KVIC & other agencies related to installation of bio gas plant installedtwo types of Biogas plant one was fixed dome and second was floating dome. Fixed domedigester was covered by concrete gas holder while floating dome digester was made up of metal(iron) sheet gas holder. Fixed dome digesters require one month for installation. After sometimes these types of digesters faced problem of scum deposition on upper surface which can notremoved easily, ultimately biogas production effected. In these plants high maintenance costwas required for removing scum. On the other hand floating gas holder (metal sheet) wascorroded due to contact with water and hydrogen sulfide. Second problem was that at the timefeeding few amounts of mud particles was present with feed, gradually this mud deposited in thelower surface of digester. Due to these problems digestion and gas formation is effected.Following problems keeping in mind we designed a low cost, easy and quick to install, durable,easy to maintain and anti corrosive type of biogas plant.


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