烟台新瑞环保科技有限公司

BLUER-PRO sulfur recovery technology is a liquid-phase oxidation catalytic technology independently developed by Yantai SUNRISE Environmental Technology Co., Ltd. It uses chelated iron ions as a catalyst and undergoes the following overall reaction in an aqueous solution:

H 2 S + 1/2 O2 → H2O + S°

This reaction can be divided into two parts: absorption process and regeneration process.

Absorption part:

Proportioning solution absorbs H 2 S gas:

H 2 S (g) + H2O ↔ H2S (l) + H2O

Ionization:

H 2 S (l) ↔ H ⁺ + HS ^-

High-valent iron ions (Fe+3) oxidize divalent sulfur:

HS ^- + 2Fe ⁺³ → 2Fe ⁺² + H ⁺ + S ⁰   

Total equation for absorption part

H 2 S (l) + 2Fe ⁺³ → 2H ⁺ + S°+ 2Fe ⁺²

Regeneration part:

Proportioning solution absorbs oxygen:

1/2 O ₂ (g) + H ₂ O ↔ 1/2 O ₂ (l) + H ₂ O

Ferrous ion regeneration reaction (Fe ⁺² )

1/2 O ₂ (l) + H ₂ O + 2Fe ⁺² → 2OH ^- + 2Fe ⁺³

Total equation for regeneration part

1/2 O ₂ (g) + H ₂ O + 2Fe ⁺² → 2OH ^- + 2Fe ⁺³

In the water proportioning solution, ferrous ions (Fe ⁺² ) and ferric ions (Fe ⁺³ ) cannot exist stably. Under normal circumstances, they easily form ferric hydroxide or iron sulfide precipitates through the following reactions:

Fe ⁺³ + 3OH ^- → Fe(OH) ₃ (s)

Fe ⁺² + S ^-2 → FeS (s)

To prevent the formation of the above precipitates, the BLUER-PRO system uses a unique chelating agent (XR-SR2), which allows the iron in the water proportioning solution to maintain a stable ionic state over a wide pH range. The chelating agent is an organic compound that encapsulates metal ions in a claw-like structure, allowing the metal ions to form chemical bonds with two or more non-metal ions.

The treatment of acid gas is accompanied by carbon dioxide (CO ₂ ) gas, especially as the partial pressure increases, side reactions that lower the pH value will occur. Carbon dioxide is easily soluble in water and will form bicarbonate (HCO ₃^- ) and carbonate (CO ₃ ^-2 ) , the reaction is as follows:

CO ₂ (g) + H ₂ O (l) ↔ H ₂ CO ₃ (l)

H ₂ CO ₃ (l) ↔ H ⁺ + HCO ₃^-    

HCO ₃^- ↔ CO ₃ ^-2 + H ⁺

To stabilize the pH value of the proportioning solution, it is necessary to add alkaline substances such as potassium hydroxide to the system, which reacts with carbon dioxide as follows:

CO ₂ (g) + H ₂ O(l) ↔ H ₂ CO ₃ (liquid)

H ₂ CO ₃ (liquid) + 2KOH ↔ K ₂ CO ₃ + 2H ₂ O

K ₂ CO ₃ + H ₂ CO ₃ ↔ 2KHCO ₃

After adding KOH, HCO is formed in the proportioning solution ₃^- —CO ₃ ^-2 buffer solution, after which CO ₂ is no longer absorbed and no longer consumes alkali, but in order to inhibit some side reactions and supplement the salt lost with the sulfur cake, a small amount of alkali still needs to be added.

Since sulfur exists in a granular form in the water proportioning solution, it must be separated by a method similar to precipitation. Generally, sulfur is formed in the absorption tower, and after adding a surfactant (XR-SR6), the sulfur particles are wetted in the water proportioning solution. Since the density of sulfur is about twice the density of water, the sedimentation rate is relatively fast. Finally, the generated sulfur is separated from the system by sedimentation.

The BLUER-PRO process can be designed to handle various hydrogen sulfide-containing gases. It can achieve over 99.99% H2 removal in many industrial applications. S removal rate. These areas cover natural gas extraction, oil refining, biogas treatment, landfill biogas treatment, coking, geothermal gas power generation, beverage industry CO 2 gas production, lubricating oil production, etc.

In these industrial productions, the gas flow to be processed ranges from several cubic meters to tens of thousands of cubic meters (flow under operating conditions), and the sulfur produced daily ranges from 0.2 - to 25 tons / per day. The amount of sulfur-containing gas processed by the system ranges from 100 ppmv of H ₂ S to 100% of H ₂ S 。

3.2 Process Characteristics

The BLUER-PRO process has all the advantages of the traditional liquid-phase oxidation catalytic method, as follows:

(1) High hydrogen sulfide removal rate, the removal rate of one-step reaction reaches 99.99% or more, and the treated tail gas H ₂ S concentration can be 5 ppm or less.

(2) Wide range of applications, can handle various containing H ₂ S gases, high selectivity.

（ 3 ) Large operating flexibility, able to adapt to the H ₂ S concentration and flow rate of the feed gas from 0-100% large fluctuations.

（ 4 ) Environmentally friendly, no three wastes are produced.

（ 5 ) Mild reaction conditions, liquid phase, normal temperature and pressure reaction process.

（ 6 ) Simple process, simple start-up, shutdown and daily operation.

（ 7 ) High economic performance, small footprint, low investment cost, and low daily operating cost.

（ 8 ) High safety performance, the system does not use any toxic chemicals, and the sulfur product does not contain H ₂ S gas.

（ 9 ) Reliable operation, unique design ensures no blockage, ensuring long-term stable operation.

（ 10) Good sulfur quality, few impurities.