Technical equipment

 

2.1. Stirring devices
To avoid floating and sediment layers, and for substrate homogenisation and substrate recirculation pressure water tight diving propeller stirring devices will be installed. The operating time of the stirring devices is regulated by the PCS (process control system).



With trained personnel, maintenance work to the stirring device can be carried out in the gas phase without shutting down each fermenter/digestor.
As a pressure relief device for the digester a mechanical over- / under pressure relief device will be installed on a stainless steel frame that is pre-positioned when concreting the digester’s roof.
As a further protection for the digester with a rising scum layer, a weight-loaded inspection window is installed as a general protection in the over- / under pressure relief device.

 

2.2. Service opening
Depending on the proportion in the feedstock stones and other sedimentation materials must be removed from the digesters. In order to guarantee a fast and practical cleaning, a service opening will be installed on each tank. Gas tight zinc-coated, walkable covers with sight glass and burst protection will be installed.

 

2.3. Digester heating
The heating of the digester is carried out by hot water circulation. The hot water is generated from the waste heat of the cooling circuit of the gas motor. The digester heating consists of welded stainless steel heating pipes, which are mounted ring-shaped on the inside of the tank.

 

2.4. Pump technology

On the inside of the final storage unit will be installed a long wave pump with stirring nozzle.

The pump pumps the fermented substrate to the pit filling station.

The stirring nozzle can be manually activated when necessary, to homogenize the fermented substrate.


The pipes of the long wave pump lead through the wall of the slurry store into the service room.

The transportation of fermentation substrates and products is carried out by the central manure distribution in the service room – both between the digesters and within the overall system.

The pipe system starts at the transfer point of the slurry store and ends at the final storage unit. The pipe system connects all tanks to one another – so that a simultaneous filling, draining and pumping of all tanks is possible.


The definition of the transportation path is set via the process control system (PLS). All necessary valves are equipped with pneumatic adjustment.

The opening and closing occurs pneumatically by the PLS.

 

2.5. Tank overflow

The overflow system allows a levelling between the digesters without the use of the pumps.

By the use of the tank overflow the substrate can be pumped between filled tanks.

Thus, at all times the biological process can be optimized in each tank of the whole biogas system.

Through the installation in the service room, pipes and manifolds can always be viewed, monitored for leaks and serviced if necessary.


 

2.6. Gas pipe

Through the gas pipe system the gas-carrying system components of the gas production facility are connected with the low pressure gas storage (membrane film storage for pressure compensation) in gas storage.


The gas-carrying pipes are non-ferrous metals, media and corrosion resistant.

 

2.7. Gas storage unit

The gas storage unit serves as a buffer between the gas production and the gas utilisation.

The total size of the gas storage unit is determined by the combustion demand of the CHP.


A volume size of approximately 2 hours usage is aimed for.

 

2.8. Gas flare

For the start-up operation and in the case of maintenance or fault-related shutdown of the combustion engine or other failures, the gas flare has to safely burn up all the produced gas.

The gas flare is a safety-related component for the whole system.



It is connected to the gas pipe and turns on automatically, if the permitted pressure or maximum capacity has been reached in the gas storage unit.

The gas flare operation safely prevents a release of biogas during a shutdown of the combustion engine.

 

2.9. Gas analysis system

The gas analysis system measures the produced gas quality. The measured values serve to set the combustion parameters for the gas engine.

Each gas producing digester is measured separately by time intervals, and controlled and recorded via the process control system.


 

2.10. Gas dehumidification

A gas-water heat exchanger is integrated into the gas dehumidification system, designed as a tube bundle heat exchanger.

All gas-contacting parts are made of stainless steel 1.4571.

The water exchanger is designed as a steel casing, including condensation water drain.

The water cooler is designed as an air-cooled liquid cooler for outdoor installation.


 

2.11. CHP

For the combustion of biogas, we currently only use GE-Jenbacher CHP aggregates. Jenbacher has decades of experience in this field and has always kept pace with developments of biogas systems.

The aggregates we use have optimal efficiencies, depending on the geographical location and the present voltage in that country.

In Central Europe we achieve electrical efficiencies at an average of 38.5 - 41.0% in the overall concept of MWK Biogas.

The cogeneration system consists in total of one gas engine. This is equipped with a flange-mounted generator and a heat exchanger for engine cooling. It is installed in the ventilated aggregate building.

The biogas-fueled engine operates as a 4-stroke Otto motor. The gas-air mixture is fed to the combustion chamber and the combustion is initiated by a spark plug.



The gas engine is equipped with sensors for monitoring and controlling. The regulation of exhaust emissions of the gas engine is realised through a gas-mixture control.

The generator is a brushless synchronous generator, suitable for operation in parallel with a network or as a backup power operation.

Exhaust silencer:

Functionality in accordance with the principles of reflection and absorption, specifically designed for the octave analysis of the exhaust noise of the combustion engine.

Materials: Gas-contacting parts in stainless steel Theoretical noise level at 10m distance about 65 dB(A) under the conditions of a free field sound level measurement.


Pipeworks:

The gas engine is fully piped and connected to the charge-air cooler and emergency cooler as well as to the heat distributor.


Including all necessary pumps and monitoring equipment for water, electricity and temperature.

CHP-Container Units:

Fast and trusted solutions with CHP-Container Units.

Easy logistics as a result of modular assembly and preassembled components.

 

2.12. Waste-gas heat exchanger

To use the waste heat of the combustion gas, a heat exchanger can be additionally connected to the hot water cycle.

The waste-gas heat exchanger is built as tube bundle heat exchanger and releases the exhaust heat into a warm / hot water circuit in horizontal or vertical construction.

The waste-gas heat exchanger operates according to the flue tube principle in counter flow.


 

2.13. Mixture cooler

For cooling the gas / air mixture a heat exchanger is used.

The mixture cooler is built as table cooler.


 

2.14. Emergency cooler

Unused engine waste heat is discharged through the emergency cooler.

The emergency cooler is built as table cooler.


 

2.15. Room ventilation

Through a ventilation system the necessary air for the combustion engine is ducted to the CHP room.


The room ventilation is supervised by room monitoring.

It monitors accumulating CH4.

The monitoring will be carried out by a type-approved measuring head with acoustic and visual alarm functions.

 

2.16. Oil supply CHP

A complete tank armature will be built for the use of the oil tanks.

It consists of a suction and return pipe with transition to the stainless steel piping system to the CHP daily tank.

The oil system has two oil pumps (gear pumps) for filling and emptying the tanks.

All oil pipes including fittings are made of stainless steel.

Monthly tank for automatic engine oil refill

The monthly tank will be installed next to the CHP in the CHP room. This tank serves as a fresh oil supply for the engine and contains approximately 250 liters engine oil. It is sufficient until the next oil change.


 

2.17. Heat usage

For heat recovery from the engine-cooling system, a cooling water heat exchanger is used on the side of the engine with external water circuits. .

The heat exchangers use the heat for thermal process control of the gas production facility and for external heat consumers.

The process heat recovery system, including process water production, hot water distribution with pump circuits, valves, safety devices, etc. will be installed in the generator room.


 

2.18. Feeding system
2.18.1. Solid matter feeding system

The solid matter feeding is carried out by a stationary mixing and dosing system with integrated vertical mixing screws.

The machine is as standard equipped with a hydraulic dosing-opening with metering valves, powered vertical mixing screws and counter blades.



The feeding is scheduled by the process control system through the roof of the digester.

The worm gear filler conveys the material by interval switching as needed to the vertically arranged mixing screws with immersion into the liquid phase of the digester.

2.18.2. Dosing equipment

The roof feeding system is as standard equipped with two separate screw tubes;

one above the concrete roof and one below the concrete roof.

So that the dosing screw or the entire solid matter dosing system can be exchanged without discharging gas.


2.18.3. Weighing equipment

The electronic weighing equipment serves to accurately measure the solids introduced into the digester.

The data is transmitted to the central control system and allows for a detailed analysis and balancing.