Methods and systems for particulate matter removal from a process exhaust gas stream

Abstract

Disclosed herein are systems and methods for reducing the particulate matter content of an exhaust gas from a carbon black process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority to U.S. patent application Ser. No. 15 / 752,331, filed Feb. 13, 2018, which is a U.S. National Stage application under 35 U.S.C. 371 of Patent Cooperation Treaty application PCT / EP2016 / 069057 filed Aug. 10, 2016, which in turn claims the benefit of priority to U.S. Provisional Application No. 62 / 205,146, filed Aug. 14, 2015. Each of these applications is incorporated by reference in its entirety herein,BACKGROUND OF INVENTION[0002]Sulfur oxides (e.g., SO2) are present in the waste gases discharged from many metal refining and chemical plants and in the flue gases (e.g., exhaust gases) from power plants generating electricity by the combustion of fossil fuels. The control of air pollution resulting from the discharge of sulfur oxides into the atmosphere has become increasingly urgent. An additional incentive for the removal of sulfur oxides from exhaust gases is the recovery of sulfur values o...

AI Technical Summary

Benefits of technology

The present invention provides systems and methods for treating exhaust gas in the carbon black industry that have several advantages. These systems and methods require less water and energy, generate less wastewater, and have higher energy recovery potential compared to conventional methods. Additionally, the modular design of these systems helps to avoid the high costs associated with conventional methods. The economic benefits of the invention can be determined based on the size and sulfur content of the exhaust gas stream being treated. Overall, these systems and methods offer a more cost-effective and environmentally friendly solution for treating exhaust gas in the carbon black industry.

Problems solved by technology

However, the large volumes of these exhaust gases relative to the quantity of sulfur which they contain can make removal or recovery of sulfur compounds from these gases expensive.

Also, while the possible by-products that may be ultimately obtained from the recoverable sulfur, such as elemental sulfur and sulfuric acid, have virtually unlimited markets as basic raw materials, they sell for relatively low figures.

In general, a reaction between a solid and gas is relatively slow and has inefficient reaction kinetics, being limited by the available surface area of the solid.

Also, certain of the resultant products do not readily lend themselves to regeneration of the starting materials (meaning the absorber material has to be replaced after its surface has been saturated) or recovery of any removed sulfur values.

Wet absorption processes (e.g., wet scrubbers) suffer from the common drawback of the exhaust gas being cooled substantially and becoming saturated with water.

This cooling of the exhaust gas can decrease overall efficiency of the process because of the additional power requirements for dispersal of the exhaust gas to the atmosphere.

Further, the associated condensation and precipitation of evaporated water containing contaminants in the surrounding environment, and the general formation of plumes at the point of emission from the plant stack, can create substantial problems.

Also, in the case of SO2 removal, difficulties can arise where economic and efficient recovery of the dissolved absorbent and sulfur values from aqueous solution is attempted.

Furthermore, poorly maintained scrubbers (e.g., those that have not been adequately cleaned) have the potential to spread disease-causing bacteria.

Furthermore, the catalyst used in WSA systems for conversion of the sulfur oxides to sulfuric acid is extremely susceptible to deactivation by chemical poisoning, mechanical blockage, and thermal degradation from particulate matter in combusted exhaust gas streams.

The use of an ESP causes a significant loss in thermodynamic efficiency of the system—cooling of the gas stream for particulate removal followed by heating of the gas stream for catalytic conversion.

In addition, the operational costs of an ESP (electricity, pressure drop, flow) can become cost prohibitive.

Wet scrubbers and conventional WSA systems are not recommended for removing SO2 from exhaust gases from carbon black production processes.

This is because exhaust gases from carbon black processes have low levels of sulfur and high levels of particulate matter and water.

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