Biogas-CNG Upgrading System

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Product origin: Changsha, Hunan, China
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US$ -1

Description





After two-stage desulphurization processes, then go through our GasDec system for carbon removal, biogas could be upgraded to make CNG, for vehicle or going into national pipeline network.

The gas quality after upgrading as below:
ItemQuality IndexComments
High thermal
value
  MJ/m3>31.4In the specific geographical area for vehicle driving, under the highest operation pressure, the water dew point shouldn't be higher than -13 degree.C; When lowest ambient temperature lower than -8 degree.C, the water dew point should be 5 degree.C lower than the lowest temperature.
CO2%≤3.0
Total Sulfurmg/Nm3≤200
H2Smg/Nm3≤15
O2%≤0.5
Comments: The above data is subject to clients' actual requirements.

The Flowchart of biogas upgrading system



Procedures of our biogas upgrading system
 
1, Biogas Generation
Biogas is generated in anaerobic reactor and stored in gas holder in low pressure. Boosted by biogas blower, biogas is delivered to wet desulphurization tower;
 
2, Wet Desulphurization
Wet chemical desulphurization technology is mainly structured as a single tower. Chemicals adopted is Na2CO3 with addition of catalysts (oxygen carrier). Chemicals is dissolved in the water, contact rightabout with biogas in the tower. More than 95% hydrogen sulfide, a small amount of carbon dioxide and other acidic substances can be absorbed by the liquid.

The pregnant solution (the liquid) would be boosted by pump to a special groove, sprayed and oxidized by means of air suction for regeneration. Meanwhile elemental sulfur is precipitated out of the liquid, to be recycled for sale.
 
3, Dry Desulphurization
Dry chemical desulphurization technology is for the purpose of fine desulphurization, mainly structured as double towers, can be used alternately or operated in parallel or in series. Chemicals adopted is usually ferric oxide. Hydrogen Sulfide is converted to solid sulfide.
 
4, Gas Cleaning
The gas is boosted by biogas compressor, then after procedures of cooling, water and impurities removal, to be delivered to decarburization unit.
 
5, Biogas Decarburization
The decarburization technology we adopt is chemical absorption. Chemical solution contacts with biogas rightabout in the absorption tower, to absorb carbon dioxide till its content lower than 3%.

The upgraded gas is discharged from top of absorption tower, to be cooled by cooler and cleaned by separator for the removal of condensate water and chemical solution. Then gas is delivered to compressor.

The pregnant solution (the liquid) returns to the regeneration tower. The precipitation of carbon dioxide is achieved through steam stripping. The precipitated carbon dioxide gets through cooler and separator, can be discharged into atmosphere directly. The barren solution from the bottom of regeneration tower is pumped through automatic flow monitoring pipeline into absorption tower for circulatory use.


This is our GasDec system.
 
1,  NG Compressor
The gas after decarburization procedure we can call it natural gas now. Its pressure rises to 22MPa or other pressure levels by natural gas compressor.
 
2, NG Cleaning
The compressed natural gas would be dried and cleaned further by automatic NG drier. The working principle of drier is pressure swing absorption, taking 4A molecular sieve as absorbent.
 
3, CNG Metering
CNG metering device is required when gas is for sale. Measuring method we usually adopt mass measurement. Eg. The mass flowmeter of our project in Henan Province of China is Emerson CNG050, accuracy could reach 0.5 magnitude. Gas is filled into CNG tank lorry through gas dispenser machine, to be delivered to standard CNG station (or Primary CNG station) as fuel for vehicle.

Main equipment list of our upgrading system
No.ItemComments
Biogas Desulphurization System
1Wet Desulphurization Tower 
2Groove,Pregnant Solution 
3Groove,Barren Solution 
4    Groove,regeneration 
5Separator 
6Dry Desulphurization Tower 
7Regeneration Pump 
8Pump,Desulphurization 
9Pump,Sulfur Foam 
10Biogas Blower 
11Electrical Monitoring 
12Alarming System 
Biogas Decarburization System
1Pump,barren Solution 
2Decarburization TowerMethane Recovery: ≥99%,
Gas quality satisfies GB18047-2000 standard
3On-line Analyzer 
4On-site control box 
5PLC System 
6Operator Station 
7On-line UPS 
8Automatic flowmeter 
9Motorized Valve 
10Pressure Transmitter 
11On-site Pressure Gauge 
12On-site Temperature Gauge 
13Liquid level Gauge 
14Frequency Converter 
15Filter 
16Storage Tank 
17Underground Groove 
18Underwater Pump 
19Biogas Compressor 
20Power Distribution CabinetAssembling Unit
CNG Compressing, drying and metering Unit
1CNG Compressor 
2Dryer 
3Gas Dispenser Machine 
Circulatory Cooling Water Unit
1Circulatory water system 
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