Lignite Drying Technology

Improve Quality and Efficiency—Tianli Energy's Lignite Steam Rotary Drying Technology

Lignite is a low-grade coal with high moisture content, high volatile content, low calorific value, and low ignition point. At present, with the near-mining of high-quality coal in China, brown coal has become the main coal used in China. Global lignite geological reserves are about 4 trillion tons, accounting for about 40% of coal reserves, mainly distributed in Europe, followed by Asia and North America. Lignite is divided into two categories, hard lignite and soft lignite. The countries with the most hard lignite reserves are the United States, Russia, and China. The countries with the largest soft lignite reserves are Russia (about 30%), and the countries rich in soft lignite reserves are Germany, Australia, the United States, the former Yugoslavia and Poland (total about 40%). Due to the characteristics of lignite, it is difficult to transport, store and sell. The high moisture content of lignite increases transportation costs, plant construction and operating costs, and even affects the normal operation of production units, reducing the economics of lignite-based power generation or coal chemical projects. How to effectively remove the high moisture in lignite is one of the important ways to solve the above problems.

According to statistics, the lignite reserves in the world are sufficient for 2,100 power plants with a generating capacity of 1,000 MW for 30 years. Currently, there are many lignite power plant projects in Germany, the United States, Australia, Indonesia, Turkey ,Serbia, etc. Lignite drying technology can reduce its moisture content, which can not only provide lignite calorific value and reduce transportation cost, but also improve the utilization efficiency of downstream equipment and reduce equipment scale. Studies have shown that removing 50% of the moisture in lignite will reduce greenhouse gas emissions from lignite combustion by 15%. The actual test shows that a lignite with a moisture content of 42.52% and a calorific value of 11.93MJ / kg, after drying and upgrading, the moisture content is reduced to 14.43%, and the calorific value is increased to 18.08MJ / kg, which is equivalent to an increase of 51.6% in calorific value . There is no doubt that lignite drying technology is of great significance for lignite power plants.

Shandong Tianli Energy Co., Ltd. signed a contract of“The Thermal Power Plant Gasification Furnace Raw Material Quality and Efficiency Improvement Project- Indirect Steam Rotary Drying System EPC Project”with Guangxi Branch of Aluminum Corporation of China Limited（CHALCO for short) in March 2018. It completed the 168h hot commissioning successfully at one time, and passed the completion acceptance. The project adopts indirect steam rotary drying technology.

The project covers an area of 200 square meters, with Steam Rotary Dryer as the main equipment. The Steam Rotary Dryer has a diameter of 4m and a length of 35m. The lignite drying output is 700,000 tons / year. The successful operation of this project not only solves the problem of poor lignite fluidity in the gasifier system, but also increases the calorific value of the lignite, which has a positive impact on subsequent gasification units, such as increasing the gas production rate and reducing the gasifier. Moisture content in the produced gas. In terms of the entire gasification system, the operating costs have been reduced. So far, the project has been running continuously for more than 2 years, and the benefits have been about 8-10 million yuan / year. It has served multiple purposes for Guangxi Branch of CHALCO and won unanimous praise from industry experts at home and abroad.

Most of the lignite drying and upgrading projects that have been constructed in the world use high-temperature flue gas for direct heating and drying, but accidents have occurred to varying degrees during the operation, which caused the unit to fail to operate normally and brought economic losses to the enterprises. Tianli Energy’s Steam Rotary Dryer has been successfully operated in many domestic industries. This successful operation on the lignite drying project of Guangxi Branch of CHALCO has great significance for the technical choice of lignite drying and upgrading in the future at home and abroad.