While fouling of the syngas cooler probably cannot be completely eliminated, it can be better managed. REI is pursuing mitigation technologies that include (a) periodic in situ tube cleaning with targeted soot blowing and (b) surface coatings that inhibit buildup of deposit material and provide easier removal of deposits. These technologies are being tailored for the conditions that exist in the convective syngas cooler used at coal gasification plants. The project team will acquire a new and improved understanding of the mechanisms governing fouling to form the basis for mitigation technologies.
Coal gasification, in conjunction with integrated gasification combined cycle (IGCC) power production, is under development to increase efficiency and reduce greenhouse gas emissions associated with coal-based power production. However, coal gasification plants have not achieved their full potential for superior performance and economics due to challenges with reliability and availability. In particular, performance of the syngas cooler located downstream of the gasifier has been an issue. The syngas cooler is a fire tube heat exchanger located between the gasifier and the gas turbine. The purpose of the syngas cooler is to cool the raw syngas from the gasifier and recover heat. Although it offers high efficiency, the reliability of the syngas cooler has generally been lower than that of other process equipment in the gasification island. Fouling of the syngas cooler can lead to poor performance, reduced equipment life, and increased maintenance costs.
The fouling mechanism in the syngas cooler is not sufficiently understood to allow equipment vendors to develop a solution. Fouling is caused by vaporized and very fine solid ash from the gasifier depositing on the fireside surfaces in the syngas cooler. The fouling deposits occur in regions where the temperatures are lower than traditional sticking temperatures for coal-fired boilers. The Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has partnered with Reaction Engineering International (REI) to develop technology to mitigate syngas cooler fouling.
The target application for the soot blower technology developed in this project is for coal gasification plants producing syngas for power generation and for refinery and chemical production applications. If successful, the soot blower technology will improve the reliability and availability of coal gasification plants, thereby reducing the United States’ dependence on foreign energy sources and decreasing greenhouse gas emissions.
Goal and Objectives
The goal of this project is to develop technology to mitigate the fouling that occurs in the gasifier syngas cooler. In support of this goal, a combination of laboratory experiments, analyses of syngas cooler deposits, modeling, and guidance from industry will be used to (a) acquire a better understanding of fouling mechanisms and (b) develop and evaluate strategies to mitigate syngas cooler fouling, thereby improving the performance of the syngas cooler.
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