Biogas and Biomass

We design, build and operate Biogas and Biomass plants that generate electricity for the communities.

TECHNICAL SPECIFICATION

The main technology of the biogas station consists of hydrolysis tank, main fermenter and one covered storing tank with decaying. Main technological parts of the Biogas Station:


  • Hydrolysis tank: 300 m3 operating volume

  • Fermenter 1: 2,960 m3 fermentation volume and 1,100 m3 integrated gasholder

  • Covered storing tank with decaying:  2,050 m3 fermentation volume and 800 m3 integrated gasholder

Biogas Station technology:

  • Feeding truck (1 pc):

Will be used for dosing solid input raw material into the hydrolysis tank. It is a stationary container with a moving belt bottom. Feedstock is fed via conveyor belt top feeding into hydrolysis tank.

  • Hydrolysis steel tank (1 pc)

Anaerobic digestion is a 4-stages biological and chemical process. There are many microorganisms involved, including acetic acid-forming bacteria (acetogens ) and methane-forming archaea (methanogens). These organisms convert the biomass into biogas. Most biogas plants still have one or several digesters where all the different bacteria have to live together (1-stage fermentation). But the different bacteria prefer a different environment (pH-value, temperature, organic acid concentration, etc) where they can work in a most efficient way.

Therefore, this project will use the aerobic hydrolysis technology. This means that the first stage of the digestion process, the hydrolysis process is now a separate process in the extra tank. Thus, more kind of biomass can be digested.


  Advanced hydrolysis steel tank is reservoir tank for incoming feedstock with

  inner diameter of  8,28 m, height 6,08 m and operating volume of  300 m3, including 

  heating, stirring, insulation and pumping.

  The tank walls will be made of steel metal sheet with threaded joints sealed by putty. The tank bottoms will be round and made of waterproof concrete.

Tank will be roofed and equipped with central mixer (agitator).

The temperature in the tank will be maintained at a mesophilic temperature of 38-40 °C and the internal heating will be provided by hot water from the cogeneration unit.

  • Fermenter (1 pc)

Main steel fermenter  covered by a gasholder is insulated (80 mm insulation material) steel tank with inner diameter 24,09 m and the tank will be 7,27 m height. The operating and maximum digestate level in the fermenter will be 6,8 m and the digestate volume will be approx. 2 960 m3. The tank walls will be made of steel metal sheet with threaded joints sealed by putty. The tank bottom will be round and made of waterproof concrete.

Fermenter will be roofed by air-supported membrane roof with an operating volume of

1 100 m3 and equipped with three lateral inclined mixers and one horizontal propeller mixer.

The temperature in the fermenter will be maintained at a mesophilic temperature of 40-42 °C and the internal heating will be provided by hot water from the cogeneration.


Technical data:

Steel tank: made of sheet steel; 80 mm thick thermal insulation material is used to insulate the tank. This is covered with a cladding made of trapezoidal sheet steel, with a surface treatment in standard RAL colors.


Integrated gas holder: this is a two-membrane gas holder with filling measurement.  

Operating pressure: 5 mbar

Max. biogas development: 500 m3 / hour.

Max. biogas consumption: 500 m3 / hour.

Max. wind load: 150 km / h.

Max. snow load: 50 kg / m2

Type of outer and inner membrane: III with strength 5000 N / 5cm

Liquid overpressure fuses SV 200/7 with exhaust capacity at 500 m3 / hour. at 5 mbar and vacuum SV 200 / -3 with suction capacity at 500 m3 / hour. at -3 mbar

Fill level indicator: electrical filling measurement with continuous transmission, transducer and its source.


Agitators:

Side inclined agitator: agitator with an inclined shaft and with 2 propellers fixed at any height, each with a diameter of 2,650 mm.

Engine drive:

            Rated power: 11 kW

            Rated voltage 400 V

            Rated frequency: 50 Hz

            Rated current: 23 A

            Frequency converter: 11 -15 kW with mains filter and inter-circuit choke for incorporation           into the given control system


Horizontal propeller agitator: this is a submersible pump specially designed for use in fermenters of biogas plants with a substrate temperature of up to 60 ° C. For safety reasons, this machine is ATEX tested and thus approved for use in explosive atmospheres 1.

            The large diameters of the propellers, together with the planetary drive for submersible     motors, enable an unusual degree of efficiency and thus effective energy savings.

            Technical data:

            Rated power: 16 kW

            Engine speed: 950 min. -1

            Number of propeller revolutions: 197 min. -1

            Propeller diameter: 1000 mm

            Rated voltage 400 V

            Rated frequency: 50 Hz

            Rated current: 35 A

            Cable length: 15 m


Fermenter engine room (1 pc): located between the fermenter and the decay storage tank. The following will be implemented in the fermenter engine room:

            Pumping: Volumetric pump with rotary pistons (1pc):

                        Process conditions:

                        Durable dry running

                        With self-priming ability

                        Frequency converter control

                        Flow rate: approx. 80 m3 / hour.

                        Differential pressure: 2.5 bar

                        Dry matter content: max. 12%

                        Power input 18kW


            Heating: The heating of the hydrolysis tank, the main fermenter and the decay storage tank  will be performed by hot water from cogeneration. In the fermenter engine room, there will be    heating distributions with heating water regulation and circulating pumps at the manifold and collector. The design will be in stainless steel pipes, insulated with mineral wool, the operating      pressure will be 200 kPa and the operating temperature will be 90/70 ° C. The heating register consisting of 6 heating coils 6 × DN50 will be placed around the perimeter of the tanks. There will also be automatic water replenishment. The entire system will be secured by expansion vessels and a safety valve. The control of the heating process will be fully automated.


            Stage I desulphurisation: The gas spaces of the main fermenter and of the decay storage tank will be desulphurised by dosing  the  air to reduce the hydrogen sulphide content of the biogas. A compressor will be located in the fermenter engine room as an air source and mechanical flowmeters, through which air will be dosed to 4 points of each tank.


            Sludge and gas  equipment: This part is realized by pneumatic knife gate valves, pneumatic ball valves and dampers.


  • Covered storing tank with decaying (1 pc)


  The decay storing - steel tank, covered by a gasholder, is an insulated steel tank with inner diameter 19,57 m and a tank height of 7,27 m. The operating and maximum digestate level in the storage - steel tank will be 7,17 m and the digestate volume will be around  2 150 m3. The walls of the tank will be made of steel metal sheet with threaded joints sealed by putty. The tank bottom will be round and made of waterproof concrete.

The tank will be roofed by air-supported membrane roof with an operating volume of

800 m3 and equipped with four horizontal propeller mixers (agitators).

The temperature in the storing tank will be maintained at a mesophilic temperature of 40-42 °C and the internal heating will be provided by hot water from the cogeneration unit.


Technical data:


Steel tank: made of sheet steel; 80 mm thick thermal insulation material is used to insulate the tanks. This is covered with a cladding made of trapezoidal sheet steel, with a surface treatment in standard RAL colors.


Integrated gas tank: this is a two-membrane gas tank with filling measurement.  

Operating pressure: 5 mbar

Max. biogas development: 500 m3 / hour.

Max. biogas consumption: 500 m3 / hour.

Max. wind load: 150 km / h.

Max. snow load: 50 kg / m2

Type of outer and inner membrane: III with strength 5000 N / 5cm

Liquid overpressure fuses SV 200/7 with exhaust capacity at 500 m3 / hour. at 5 mbar and vacuum SV 200 / -3 with suction capacity at 500 m3 / hour. at -3 mbar

Fill level indicator: electrical filling measurement with continuous transmission, transducer and its source.


Agitator:

Horizontal propeller agitator: this is a submersible pump designed for use in the fermenters of biogas plants in a non-explosive ATEX design.

            Technical data:

            Rated power: 15 kW

            Rated speed: 340 min. -1

            Propeller (made of stainless steel) diameter: 810 mm

            Voltage: 3 × 400 V

            Frequency: 50 Hz

            Rated current: 30 A

            Cable length: 10 m


  • The CHP – combining heat and power cogeneration unit (1 pcs)

The combining heat and power cogeneration unit:  the cogeneration unit in the container

  outdoor design consists of two engine-generator modules containing an engine set with a

  generator, a technological module, an exhaust silencer and a free-standing electrical

   switchboard containing a control and power section.   


  The engine is twelve-cylinder, the generator is with variable power, while the maximum

  possible electrical hourly power of the engine is 2 * 500kW. The engine is also equipped with

  operational and emergency air coolers located on the container. The heat from the cogeneration

  unit is collected and led via a heat exchanger to the fermenter engine room.


Basic technical data – CHP Unit:

            Nominal electrical power: 2 * 529 kW MAN

            Maximum heat output: 2 * 623 kW

            Electrical efficiency: 39,8%

            Thermal efficiency: 46,9%

            Total efficiency: 86,7%

            Biogas consumption 9,0-9,1 MJ / kWh

            Cogeneration unit engine:

                        Number of cylinders: 12 in V

                        Compression ratio: 13,6: 1

                        Operating speed: 1500 min-1

                        Maximum engine power: 1058 kW

  • Gas treatment unit (1 pc)

This facility will modify biogas befor use in a combustion engine of the CHP cogeneration unit. The gas treatment unit is provided with the following functions:

            1. Biogas cooling and condensation moisture removal

            2. Biogas heating by heat contained in the biogas feed

            3. Reduction of hydrogen sulfide content in biogas


The device is composed of the following machine parts:

Gas cooler

Liquid cooler

Recuperation exchanger

Container with activated carbon

Measurement of temperatures and pressures

Blower



  • Residual gas burner (1 pc)

Residual gas burner is equipment located behind fermenter  and serves for emergency disposal of biogas during maintenance of the cogeneration unit. Its functions will be automatically controlled by the control system.


Technical parameters:

Biogas flow: 100 - 750 Nm3 / h (1: 5)

Methane content in biogas: 30 - 65%

Biogas pressure in front of the burner: 60 - 120 mbar

Calorific value: 651 - 3120 kW

Flue gas outlet pipe diameter: 800 mm

Flue gas outlet pipe material: stainless steel 1.4571

Continuous flame monitoring with UV sensor

The control is fully automatic



  • Separator (1 pc)

   At the outlet of the decay storage tank, a separator with efficient filtration of wastewater (max. 1% dry matter) will be placed. Wastewater will be pumped into the hydrolysis tank for diluting the input raw material - straw



  • Electrical switchgear and switch & control room (1 pcs)

Electrical switchgear is located next to the main engine room of the fermenter.

In separate container there will be a control room and a sanitary facility with toilet.

The entire technological process of the BGS plant will be fully automated with monitoring on the central control unit and with the possibility of monitoring on another PC (in a farm building, at home etc.).


BGS Process Control:


1. The following variables from the main fermenter, the storage tank and connecting

pipelines will be continuously read and evaluated:

            (a) biomass flow rate

            (b) biomass temperature in the fermenter and the storage tanks

            (c) filling of the fermenter and storage tank


2. The biogas will be harvested in the main fermenter and in the covered decay storage tank.

The following variables will be continually read and evaluated in the  BGS stations:


            (a) biogas flow rate

            (b) biogas pressure in the fermenter and the storage tank

            (c) methane content in biogas

            (d) carbon dioxide content in biogas

            (e) the concentration of hydrogen sulphide in biogas

            (f) oxygen concentration in biogas


All mixing and  pumping equipments and covering of the tanks with gas holder will be from renowned German and Austrian manufacturers – Baur, Streisal, Börger.

 

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