Discussion on the design scheme using a specialized vane separator for anti-clogging of liquid sulfur exhaust gas in sulfur recovery units as a sulfur capture device

Sulfur recovery units are installed in many types of industrial enterprises, including petrochemical companies, coal chemical plants, natural gas processing facilities, fertilizer manufacturers, and pyrite metallurgy plants. During the operation of sulfur recovery units, one of the most troublesome issues for the operators and managers of such units is the frequent clogging of the exhaust gas pipelines by sulfur, as well as the maintenance and cleaning required as a result. This leads to repeated cases of sulfur content exceeding the allowed limits in the exhaust gases, which in turn results in penalties. The maintenance and cleaning of sulfur exhaust pipeline equipment, which is frequently clogged by sulfur, involves harsh working conditions, high labor intensity, significant safety risks, and it is often difficult to find effective solutions.

Regarding sulfur recovery process packages, many companies both domestically and internationally offer their own such packages; among them, those from several established European companies are relatively more well-known for their sulfur recovery process packages. However, upon examining the sulfur recovery process packages of these domestic and foreign companies, it is found that the technology related to sulfur capturers in these packages remains at the level of the late last century without any technological upgrades, with traditional wire mesh demisting technology being used for sulfur capturers.

The sulfur catchers designed in many sulfur recovery process packages not only employ conventional barrier-type mesh defoaming technology, but also do not pay sufficient attention to effective solutions for sulfur separation during operation in the gas flow. As we have mentioned in previous technical articles on the capture and separation of sulfur droplets from gas streams, it is only by accurately understanding the changes in the physical properties of sulfur within the gas stream that it is possible to resolve both the issue of separating sulfur from the gas stream and the problem of sulfur clogging. Solid sulfur itself exists in several solid aggregation forms such as alpha, beta, and gamma, and there is a process of transition from solid to liquid followed by gas, as well as a direct sublimation process from solid to gas. Sulfur present in the exhaust gas stream in a sublimated gaseous form is difficult to remove through energy-efficient, low-consumption, and environmentally friendly kinetic separation methods. Only sulfur in forms different from its gaseous state, such as solid sulfur and liquid sulfur, is amenable to kinetic separation. Solid sulfur and liquid sulfur within a certain temperature range have very poor fluidity and are difficult to transport; therefore, in kinetic separation, it is necessary to create conditions to avoid this as a prerequisite for the separation process.

The operation of sulfur recovery units has shown that, firstly, there are issues with the technical selection of sulfur capturers in the process package; secondly, the conditions for sulfur capture and separation are not properly managed, resulting in frequent blockages of equipment in the exhaust gas pipelines. The image below shows the sulfur deposition blockage at the inlet of the exhaust gas exhaust fan:

Next, we will conduct a discussion and analysis using as an example a technical upgrade project carried out with the assistance of a domestic petroleum engineering company: in this project, specialized anti-clogging vane separators from Novenergy Technologies were installed in the exhaust foam capture and separation units of the liquid sulfur storage tanks in the sulfur recovery systems of Russian oil refineries with high sulfur content.

This post was last edited by luoli519 on 2020-8-31 at 17:22. In the liquid sulfur storage tank of this Russian oil refining company’s sulfur recovery unit, the inlet pipe for liquid sulfur and the exhaust pipe are arranged in a combined “T-shaped” configuration at the top of the storage tank; they are also insulated using steam heating. The diagrams provided by the owner are as follows:

This post was last edited by luoli519 on 2024-4-7 at 10:57. The sulfur recovery unit of this refinery originally used an exhaust gas sulfur capture device equipped with a liquid sulfur storage tank; this device was installed at the top of the liquid sulfur storage tank, near the end of the exhaust gas outlet pipe. It utilized a conventional, simple mesh separation element arranged horizontally across the cross-section of the 10” diameter exhaust gas pipeline, with steam jackets used for heating and insulation. Please refer to the structural schematic diagram provided by the owner below.

The last edit to this post was made by luoli519 on 2020-8-31 at 17:36. The demister indicated in the exhaust gas diagram of the owner’s liquid sulfur storage tank is of the mesh type; moreover, the York 931 type with the highest porosity was chosen to prevent clogging at the expense of separation efficiency. Please refer to the table below, provided by the owner, showing the original material and model specifications of the wire mesh demister:

The owner reported that the York 931 type with the highest porosity was chosen for the sulfur catcher in the original process package because sulfur has a wide melting range and high fluidity, which can easily cause clogging of the mesh; furthermore, the diameter of the exhaust pipe is 12”, which is relatively small. However, in actual operation, it was found that the York 931 screen sacrifices its separation efficiency due to its high porosity aimed at preventing clogging, which results in a significant amount of liquid sulfur foam being carried away with the exhaust gases, leading to severely elevated sulfur content in those gases. The owner had also tried to use York 431 mesh in place of York 931 mesh, but the low porosity of the York 431 mesh led to a sharp increase in operating pressure drop, which in turn caused problems with the exhaust gas discharge from the sulfur storage tank and resulted in pressure buildup. Therefore, the owner decided to carry out a technical upgrade by using a vane separator to replace the existing wire mesh separation element in the original exhaust pipe.

The feather-leaf separator is used for the technical upgrading of sulfur capture systems, and its features are: 1. High gas processing capacity, suitable for large-scale production； 2. The feather separator designed through the platform system design based on precise dynamics separation technology enables precise and quantitative separation efficiency ； 3. Low pressure drop, only 1/8 to 1/6 of that of traditional screen separators, thus saving energy ； 4. It offers great operational flexibility, enabling efficient operation within the range of 15% to 130% ； 5. It has exceptional tolerance to solid particles and waxy, sticky substances present in the airflow; it does not get clogged, requires no spare parts, and results in low operation and maintenance costs. 6. It features a top-opening design, which facilitates maintenance and disassembly.