1. biogas production process

Fig. 1 Process Flow Diagram

Brief Description of Main Process Flow of 2.
 

(1) Biogas purification process

The biogas produced by the anaerobic fermentation tank is a mixed gas containing saturated water vapor, which contains H2S and suspended granular impurities in addition to CH4 and CO2. H2S is not only toxic, but also highly corrosive. Excessive H2S and impurities will endanger the life of subsequent equipment, so desulfurization, dehydration and other purification treatment is necessary.

wet desulfurization treatment:

Due to the high content of hydrogen sulfide in biogas, the double tower parallel desulfurization process of complex iron method is adopted. The biogas enters from the lower part of the first-stage packing absorption tower and the second-stage packing absorption tower connected in series, and contacts with the desulfurization liquid from top to bottom in the two-stage packing area in countercurrent. The hydrogen sulfide is absorbed by the desulfurization liquid, and the desulfurized biogas is supplied to the pretreatment device through the outlet pipe after the demister.

● Desulfurization liquid is alkali liquid containing complex iron catalyst. Desulfurization liquid that has absorbed hydrogen sulfide flows into rich liquid tank from the bottom of packed absorption tower, then is pumped into regeneration tower under pressure by rich liquid pump, and is fully mixed with air that self-sucks into ejector. After reaction, it enters regeneration tower and is further oxidized and regenerated in regeneration tower. The regenerated lean liquid flows into lean liquid tank from the upper part of regeneration tower and is sent to absorption tower for circulating absorption by lean liquid pump.

● The elemental sulfur precipitated in the regeneration tower is suspended in the annular tower at the top of the regeneration tower and overflows into the foam tank. In the foam tank, the sulfur-containing foam is filtered by a centrifuge to separate elemental sulfur. The filtered clear liquid is returned to the lean liquid tank by a reflux pump for recycling.
The working principle diagram of the desulfurization device is shown in the following figure:

(2) Biogas storage process

As shown in Figure 2 and Figure 3. The membrane gas storage cabinet consists of an outer membrane, an inner membrane, a bottom membrane and a concrete foundation. The inner cavity enclosed by the inner membrane and the bottom membrane is used for storing biogas, and the outer membrane and the inner membrane are airtight. The outer membrane is inflated to a spherical shape. The gas storage cabinet is equipped with an explosion-proof blower, which can automatically adjust the gas inlet/exit volume to keep the gas pressure in the gas cabinet stable. The inner and outer films and the bottom film are made of high-quality film materials, which are welded by HF welding process. The materials are specially treated with high-strength polyester fiber and acrylic varnish. The gas storage cabinet can resist ultraviolet rays, prevent leakage, do not react with biogas or be affected, and the tensile strength is strong, and the applicable temperature is -30~70 ℃.

Membrane gas storage cabinet is easy to install, time-consuming, generally only a few days. The biogas inlet/outlet pipe and condensate drain pipe are embedded during the construction of the concrete foundation. During the installation of the gas holder, it is first sealed with the bottom membrane through special sealing technology. The bottom membrane is fixed on the concrete foundation. Then the inner membrane, the outer membrane and the sealing ring are installed in turn. The sealing ring is fixed on the concrete foundation with embedded bolts or chemical bolts to complete the installation of the gas holder.

3. technical characteristics

(1) The concentration of TS in the anaerobic reaction system reaches 10.79%, which can effectively reduce the amount of biogas slurry generation and energy consumption;

(2) After an independent biological pretreatment process, the maximum biogas production can be achieved, and the volume of the main fermentation can be reduced, saving investment;

(3) Co-fermentation of mixed materials, coordination of nutrient ratios, and improvement of system gas production;

(4) The anaerobic reactor adopts corrosion-resistant, high-hardness thermal spraying plate assembly tank, and the middle shaft agitator with good mixing effect and low operating cost;

(5) By using a mud heat exchanger to recover the heat in the anaerobic fermentation discharge, the consumption of external heat sources can be effectively reduced, thereby reducing operating costs;

(6) the use of heat preservation and warming system to reduce heat loss;

(7) the use of cost-effective wet desulfurization technology;

(8) the production of efficient solid, liquid organic fertilizer;

(9) Adopt efficient and humanized remote monitoring system.