When designing a biogas plant, the choice of tank form is closely related to the process design, and is also related to the selection and design of the equipment supporting the tank. The comparison between the two is as follows:
From the perspective of process design, both tank forms can adopt the CSTR reactor form. The integrated fermenter does not require a separate gas storage cabinet. The hard-top fermenter requires a separate gas storage cabinet, the process flow in the biogas production stage is long, and the electrical control and operation are relatively complex.
From the perspective of agitator configuration, the integrated fermenter is generally equipped with side stirring, which is reasonably arranged according to the size of the fermenter and the characteristics of the material (3, 4 or 5 units can be arranged at a reasonable height and angle position). The agitator has high operating flexibility and can achieve homogenization of material stirring. The entire tank has basically no dead angles. The hard-top fermenter generally uses a central agitator, which is generally equipped with three or four layers of stirring blades. Dead angles are easily generated around the bottom of the tank, and there is only one agitator. If a failure occurs, the entire fermentation substrate will not be stirred, and the operating reliability is relatively poor.
From the perspective of construction, the integrated fermentation tank is relatively short, with a tank body of 6,000 m3 and a height of only about 7m. The construction difficulty is small, and the construction safety and quality are easier to guarantee. The hard-top fermentation tank is tall, with a tank body of 6,000 m3 and a height of about 20m. The construction difficulty is large, and the construction safety and quality are not easy to guarantee. It is necessary to increase the investment in construction measures and increase the construction cost.
From the perspective of biogas purification, the integrated fermentation tank can realize biological pre-desulfurization in the tank, and the biogas rough desulfurization process is realized in the fermentation tank. The entire inner membrane support system provides a place for the growth of desulfurization bacteria, and the biogas coming out of the fermentation tank has undergone pre-desulfurization. For the hard-top fermentation tank, a biogas biological desulfurization device needs to be built outside the tank to perform rough desulfurization of the biogas. The project area is increased and the process is relatively complex, which increases the difficulty and cost of operation.
From the perspective of project land use, the use of hard-top fermentation tanks requires additional land for floor-standing double-membrane gas storage cabinets and off-tank bio-desulfurization devices compared to integrated fermentation tanks, which increases the overall investment of the project.
The choice of tank form can be made according to the actual situation of the project, such as process design, material type, site size, maturity of supporting agitator equipment, etc. The best one is the one that suits you.
