Liquid SO2 Plant Via SO3 Reduction SO2 Production Of Sulphur Dioxide

Product Specification

Liquid SO2 Manufacturing Plant

Liquid SO2 Manufacturing Plant via SO3 reduction

Liquid sulphur dioxide finds diverse applications across industries and there are several methods to produce it. We recommend integrating a liquid sulfur dioxide production system with a sulfuric acid plant, utilizing the sulfur trioxide-sulfur method. This approach involves reacting liquid SO3 with sulfur to reduce SO3 to SO2.

The method features a streamlined production process, established and reliable technology, a compact footprint, minimal equipment requirements, low operational costs, easy maintenance, and a relatively clean operation. It avoids generating industrial wastes and other difficult-to-handle by-products.

• Raw Material Handling

These raw materials are sourced as follows:

Liquid sulfur - Solid sulfur is melted with steam in the sulfur melting section and then filtered to produce clean liquid sulfur;

Liquid SO₃ - The flue gas from the third converter pass is cooled through the heat exchanger III and enters the oleum absorption tower, where part of the SO₃ is absorbed. The oleum then evaporates to release high-purity gaseous SO₃, which is condensed to produce liquid SO₃.

• The Reaction Process

The reaction proceeds as follows:  

    2SO₃+S=3SO₂

The process is designed as a two-stage system for SO₂ generation. In the first stage, liquid sulfur reacts with liquid SO₃ in an enamel reaction kettle. In the second stage, the SO₃ gas on the surface of the enamel reaction kettle reacts within a solid sulfur reactor. Both the SO₃ gas on the reactor's surface and the SO₃ gas produced from the reaction enter the solid sulfur reactor simultaneously. A mesh filter is installed at the outlet of the solid sulfur reactor to remove sulfur particles and other solid impurities. 

• Condensation and Finished Product Process

The liquid SO₂ condenser employs a tubular structure. SO₂ gas from the mesh filter enters the shell of the condenser while circulating cooling water flows through the tubes. The condensed liquid SO₂ is collected in a metering tank. There are two metering tanks, and the liquid SO₂ flows by gravity from these tanks into the liquid SO₂ storage tank. The storage tank is equipped with remote pressure and liquid level monitoring, a pressure relief system, and a boosting system. It also features emergency shut-off valves, gas leak alarms, and an alkali wash spray system.

Additionally, systems to prevent leaks, enforce ventilation, and maintain negative pressure are in place during sulphuric acid shutdowns.

Chart 1 - Liquid sulfur dioxide production using the SO3-sulfur method

• High-Purity Liquid SO2 Production: This method for producing liquid SO2 eliminates the need for compressors, preventing oil contamination and ensuring minimal residuals in the final product. Additionally, the low water content of the starting materials, liquid SO3, and liquid sulfur, translates to very low moisture levels in the resulting liquid SO2.
• Reduced Investment Costs: Several factors contribute to the lower investment costs associated with this method. The process itself is concise, requiring minimal equipment and occupying a small footprint. Furthermore, the use of liquid SO3 and liquid sulfur, which are relatively non-corrosive materials, allows for the construction of most equipment from cost-effective carbon steel. Only the reactor and specific components of the liquid SO2 condenser necessitate special materials or stainless steel.
• Environmentally Friendly Process: This method stands out for its environmental benefits. It generates no industrial waste and avoids the production of byproducts that are difficult or expensive to treat.
• Energy Efficiency: The process boasts low electricity and steam consumption. During operation, only essential equipment like metering pumps and circulation pumps are active. Steam is primarily used for initial startup and maintaining optimal temperatures in the liquid sulfur and SO3 handling systems.

In Conclusion, The SO3-sulfur method offers a straightforward approach to liquid SO2 production with numerous advantages. It delivers high-quality products with minimal impurities, requires lower investment due to a compact and less equipment-intensive process, and minimizes energy consumption. Additionally, the method's minimal corrosiveness and lack of problematic byproducts make it an environmentally friendly choice. This approach is particularly suitable for regions with established liquid SO3 production facilities.

Figure 1~5. 70kta add-on liquid SO2 package of CMOC Group KFM 300kta sulfur-burning acid plant