Drying Lignite Production Line Industry

1 Introduction

Lignite is the youngest coal in the latest forming solid fossil fuels. It has high explosibility and flammability due to its high volatile; it has low heating capacity and fixed coal content due to its high moisture, which is generally up to 40% and very difficult to remove. Moderate ash content and high tar content make it very necessary to take desulfurization system into considerate during the drying process.

Large coal mines of China that produces lignite have been found mainly in Inner Mongolia. In order to develop lignite utilization, we have carried out comprehensive cooperation with Datang International Group, Datang International Chemical Company, Datang International Chemical Engineering Design Institute, Hebei Electric Power University, Beijing State Power Design Institute (formerly Hebei Electric Power Design and Research Institute) and so on. At the same time, we have signed 500 tons / year lignite drying process line contract.

Pay attention to the following requirements during the lignite drying process:

1. We need explosion protection system no matter in lignite crushing system, conveying systems, warehousing systems or going into the rotary dryer.
2. We should keep the outside air (fresh air) from the lignite rotary dryer and seal the burner (stove), rotary dryer tightly.
3. Lignite drying system process should use fully automatic production line process line and install explosive alarm system in every explosive point. It needs to cut off all power immediately when the explosive gas is excessive, as long as the factory whistle, alarm, evacuation. The entire production line should be far away from the electrical control center, and arrange patrol in DCS. At the same time, we should avoid manually operated system since it have been safety incidents and equipment accidents in lignite drying production line due to not following the design specifications.

The lignite has high tar content and its moisture was composed by internal water and external water. So during lignite drying process, it needs an installation of chiller in the outlet of the lignite at the end of the lignite rotary dryer. In this case, we can achieve security storage, to be packaged and transported.

To sum up, lignite drying is different from drying other materials, which should be paid special attention! We must not build lignite drying process line with conventional means.

2. Block diagram of the new lignite drying process line (downstream process):

Target:

1. Lignite drying capacity: first moisture 30% ~40%, final moisture 8%~15%.
2. Lignite heat (heat value): from 3400 ~ 3700Kcal / kg to 5000 ~ 5500 Kcal / kg or more, making lignite the burning for thermal power plants or other industrial coal furnace.