Blast Furnace Gas Desulfurization by Magnesia Injection
Abstract
The purpose of this paper is to compare the advantages and disadvantages of blast furnace gas desulfurization by magnesia injection with other desulfurization technologies. Blast furnace gas is the main by-product of the blast furnace smelting process, which consists of a mixture of carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), hydrogen (H2), hydrogen sulfide (H2S), and small amounts of hydrocarbons, free sulfur and dust. Due to unfavorable environmental conditions caused by emission of SO2, a lot of attention has been paid to emissions reduction of blast furnace gas. There are several possibilities to reduce the sulfur content of blast furnace gas, among which the most common are dry or wet scrubbing techniques. Wet scrubbing techniques are the most used because they are more efficient than the dry scrubbing process. Magnesia injection is a wet scrubbing technique that is widely used. This process has some advantages over other desulfurization technologies, such as low capital investment, high removal efficiency and low operation cost.
Introduction
Blast furnace gas is a by-product of the iron and steel industry, produced in blast furnaces during the smelting process. It is composed of a number of components including carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), hydrogen (H2), hydrogen sulfide (H2S and small amounts of hydrocarbons, free sulfur and dust. The amount of blast furnace gas produces can vary greatly depending on the type of blast furnace and the ore used.
Due to its composition, blast furnace gas is a pollutant and has an impact on the environment. For example, hydrogen sulfide (H2S) is an odorless and toxic gas that can be lethal to humans and animals in large concentrations. Therefore, technologies to reduce the emissions of blast furnace gas have been developed.
One of the most widely used technologies is magnesia injection. This process uses a slurry of finely divided hydrated magnesium oxide injected into the blast furnace gas to convert the sulfur dioxide of the gas into magnesium sulfite (MgSO3). This process has some advantages over the other desulfurization technologies, such as low capital investment, high removal efficiency and low operation cost.
Advantages of Magnesia Injection
The main advantage of magnesia injection is that it is a cost effective process. The capital investment required for implementation is low, as it simply requires the purchase of the materials needed for injection. Additionally, magnesia injection is quite efficient in removing sulfur dioxide from the blast furnace gas. The sulfur dioxide removal efficiency can reach up to 90%, depending on the operating conditions.
The magnesia injection process also has other advantages, such as low operating costs and less maintenance requirements. The operating cost is significantly lower than other desulfurization techniques due to the low power consumption required and the recovering of the spent magnesia. Additionally, the process requires little maintenance, which further reduces the operating costs.
Moreover, the process can be easily integrated with the existing plant structure. The injection system only requires a storage tank, a pump and a dosing system, which can easily be connected to the existing pipe work. This allows the magnesia injection process to be quickly and easily implemented.
Disadvantages of Magnesia Injection
Despite its advantages, the magnesia injection process does have some disadvantages. Firstly, the process is not capable of removing all the pollutants from the blast furnace gas, particularly the hydrocarbons and dust. Secondly, the process is not very efficient at low sulfur dioxide concentrations. Such low concentrations require high injection rates to achieve a reasonable removal efficiency, which increases the operating costs.
Conclusion
Overall, magnesia injection is a cost effective desulfurization technique with high removal efficiency that can be easily integrated into existing blast furnace operations. The process has significant advantages over other desulfurization techniques due to its low capital investment and operating costs, as well as its high sulfur dioxide removal efficiency. However, it is not capable of removing all the pollutants from the blast furnace gas, particularly the hydrocarbons and dust. Therefore, it is important to consider the potential emissions of other pollutants when choosing a desulfurization technology.
