Technical Proposal for Desulfurization on 300 Cubic Meter Biogas

Part 1: Project profiles

According to the need to design to build a set of desulfurization equipment for handling capacity of  300 m3 / h biogas desulfurization equipment.

Desulfurization design principles:
A1 use advanced, mature, reliable technology and equipment.

A2 process scheme can fully meet the requirements of national standards for civil usage of biogas.

A3 guarantee the rationality of the process and long-term stability of operation.

A4 practical and conservation investment combined.

A5. Customers actual biogas dosage of 300Nm3 / h, hydrogen sulfide content 7000PPM / Nm3, because the higher amount of hydrogen sulfide, so use processing capacity of 300Nm3 / h methane or biogas desulfurization system.

Part 2: Desulfurization equipment Process Description

1.    desulfurization system process:
At present, the methane gas desulfurization process basically is divided into two types: one for dry desulfurization, and the other for wet FGD. Dry FGD is divided into iron oxide desulfurization and activated carbon desulfurization. The common problem of the two kinds of dry desulfurization methods is that the sulfur capacity of desulfurization agent is too small, less adjustment of the operation load, and difficulty of recycling of desulfurizing agent.

2.    Our proposed biogas desulfurization method is Wet desulfurization method (COS method), with advantages of: stable operation performance, high desulfurizing efficiency, and lower consumption of raw materials.

With the rapid development of science and technology in recent years, we have achieved significant development in the areas of desulfurization, the desulfurizing upgrading speed quickly. The CoS new family of efficient desulfurization catalyst is developed to meet the demand of the current market demand, the newly developed high-tech innovations, technical performance has reached international advanced level. Based on extensive research of the desulfurization agent market, a detailed analysis of the advantages and disadvantages of the desulfurizer at home and abroad, collecting opinions from customers, according to the plant changes in the level of sulfur content in the actual situation and in the biogas, and constantly improve the product formulation and use of technology, developed a the CoS new highly efficient desulfurization catalyst, it has outstanding advantages of low consumption, low cost. The CoS efficient desulfurization catalyst is a kind of dual control of metal phthalocyanine cyanide cobalt compounds, a desulfurization catalyst of high activity, mainly used for liquid phase catalytic oxidation desulfurization decyanation, the desulfurization efficiency of 99% or more, decyanation efficiency of 98%, so more than 60% of the organic sulfur can be removed. And good technical, economic and social benefits have been significantly achieved for the end users. The CoS efficient desulfurization catalyst, a new generation of desulfurization catalyst produced/developed though further improvement of the active components and optimization of the production process, when compared with former catalyst, has the advantages of simplicity in production, high desulfurization efficiency, high sulfur capacity, high adoption of biogas, clear regeneration solution, less block to equipments towers, easy sulfur removal, low consumption and low cost. It is the first option as efficient desulfurization catalyst in the desulfurization of fertilizer, coking and other types of bio gas desulfurization process.

3. The physical and chemical properties of the catalyst:

Appearance: blue-gray powder.

Density: less than or equal 0.96g / cc

Main ingredients: 92%

Water insoluble matter: less than or equal 3.0% have a good solubility in water or an alkaline aqueous solution.

Soda ash in aqueous solution was sky blue, pale green in ammonia.

Does not decompose in the acid medium, good chemical stability. The catalyst itself is non-corrosive, non-toxic.

4.     the usage and characteristics:

CoS desulfurization catalyst can be widely used for various types of desulfurization for gases as: biogas, producer gas, city coal gas desulfurization process gas wet air oxidation desulfurization. The product is of non-toxic, non-corrosive, non-polluting. Whether in the normal temperature and pressure or pressured conditions, regardless of ammonia or soda ash absorbent, the catalyst is able to maintain the stability of the desulfurization efficiency, when used or without additional co-catalyst. Its pre-activation process is simple, time is short, and hydrogen sulfide removal rate of up to 99%, organic sulfur removal rate of up to 60%, hydrogen cyanide removal rate of up to 98% The product has the characters of  high activity, long operation life, high anti-cyanide hydrogen poisoning, it can dissolve deposition of sulfur and attached sulfur in the desulfurization unit within the system.
So it can also clean system equipment. The advantages of high sulfurization capacity, regeneration, larger suspended sulfur particles ( which is conducive to separation, do not block the tower, the removal of sulfur high purity, non-corrosive, it does not produce accumulation in the desulfurization unit without the problem of waste water treatment, no environmental pollution, can reduce the resistance of the system, reducing energy consumption, so that the equipment to extend the maintenance period, the apparent decline in the cost of desulfurization. When in operation, the process is very simple without need to change the original process, no additional equipment and very convenient to  replace the old desulfurizing equipments and process.

5.     Chemical process: taking Sodium for example

The Chemical absorption reaction for Removal of H2S

H2S+Na2CO3==NaHS+NaHCO3NaHS+(x-1)S+NaHCO3==NaxSx+CO2+H2O

Analysis of sulfur reaction of catalytic oxidation

2NaHS+O2==(add with CoS)==2NaOH+2S!

Na2Sx+H2O+1/2O2==add with CoS==2NaOH+Sx!

Catalytic oxidation reaction of desulfurization of organic sulfur

COS+2Na2CO3+H2O==Na2CO2S+2NaHCO3

RSH+Na2CO3==RSNa+NaHCO3

Catalytic oxidation reaction of organic sulfides

2Na2CO2S+O2==(add with CoS)==2Na2CO3+2S!

4RSNA+O2+2H2O==(add with CoS)==2RSSR+4NaOH

(following is Chinese version of above.)

a)     On the use of devices in the liquid phase catalysis, the use of sulfur gas desulfurization:
(1), the preparatory work
With the availability of a barrels of capacity of 50-150 liters, the barrel is fit with feeding pipe and valve,  add water, ammonia, lye or desulfurization liquid, then add catalyst to the desulfurization demand for the plant with the initial dosage about 20-30PPM. After the addition of catalyst, stir the solution a few times with air blowing or wooden stick to let the catalyst dissolved in the liquid, and then wait it  activation for 4 hours, during which every one hour stirring one times, to ensure full activation.

It should be noted that the liquid can not be used in the case of activated liquid in white color, and it can be used if the it is Sky-blue solution or green liquid.

 (2), the input method

Feed the catalyst solution after it is fully activated, slowly and evenly to join the thin liquid sump or fluid regulator, pay attention not to add the solution to the sulfur foam layer to prevent the loss of the catalyst with the foam drainage. Three hours after activated catalyst solution into the system, a large number of bubbles of sulfur will appear, then intensive foam sulfur removal work should be done, within 1-2 days after the desulfurization the solution will return to normal.

 With the deposition of sulfur and sulfur-attached cleared, the solution may be suspended/floated  with high sulfur content, H2S content can sometimes fluctuate slightly after the desulphurization, then you can increase the amount of air into the same, and then the removal of the system sulfur foam is gradually turning into normal.

(3), Continued to Feeding method
Desulfurization solution composition and catalyst recruitment is calculated to device and operation conditions, then optimize the best added amount, usually it needs Cos 0.5KG for removal of 1kg H2S.

A1: Diagram: Process of Desulfuriztion

A2: Desulfurization indicators:
Media: Biogas

Hydrogen sulfide content before the desulfurization: 7000PPM/m3
Desulfurization of hydrogen sulfide content: 50PPM/m3
Pressure loss: ~ 1000Pa
Note: after the desulfurization of biogas, the carried water in the biogas should be removed, it is recommended that cold dryer to dry the biogas.

A3: desulfurization equipment selection and description:
(1) desulfurization tower:
Role: the desulfurization solution and H2S-biogas countercurrent contact reaction to removal of H2S.
Specifications: Φ1020/Φ1020, × 9000
(2) rich liquid pool:
The role: sulfur dialyzing reaction of the lye of H2S-rich solution
Specifications: Φ1400 × 4000
(3) injection of renewable slot:
Role: the use of inhaled air phenol-state oxidation to generate the quinone state matter.
Specifications: Φ2000/Φ1500, × 5000

(4) the thin liquid sump:
Role: lye storage after recycling.
Specifications: Φ1400 × 4000
(5) dosing tank:
Role: the preparation of tannin extract desulfurization solution
Specifications: Φ1200 × 1100
(6) desulfurization pump:
Role: the desulfurization solution to fight to the desulfurization tower
Specifications: KLW65-200K, Q = 50 / h, H = 50m
Parameters: P = 15KW
(7) regenerative pump:
Role: the H2S-rich solution is sent from the rich sump jet renewable slot
Specifications: KLW65-200K, Q = 50 / h, H = 50m
Parameters: P = 15KW
Quantity: use two spare units (desulfurization and regeneration Share this standby pump)
(8) dosing pump:
Role: the preparation of the dosing tank good tannin extract desulfurization solution transported to the poor sump
  Specifications: 50YW15-15
Parameters: P = 1.5KW
Quantity: choose one set