How should the tar residue separated by the gas-water tar separator in the Luchie furnace be disposed of?

It should be possible to send it back for burning; otherwise, it’s difficult to deal with it – it probably counts as hazardous waste

The design concept of returning tar to the furnace in the Luchi process is highly advanced: it enables dust suppression as well as the reuse of that tar, while also increasing the gas production volume of the gasification furnace. However, to date, there are no successful cases of such recycling in China； To better address the issue of handling tar containing dust, it is necessary to start at the source, that is, by strictly controlling the requirements for the coal fed into the furnace (particle size, crush strength, and thermal stability). By reducing the amount of pulverized coal used, the amount of dust in the raw gas is also reduced (the design standard is generally <1% by weight of the coal fed into the furnace). With less dust in the gas, less dust needs to be removed through washing. This approach reduces the amount of dust in the gas water at the source, lessens the workload associated with separating crude tar, and thereby improves the quality of the tar containing dust ； The currently safest approach is to use a set of three-stage separators (for separating water, dust, and oil). This allows the dust-containing tar to be separated from its oil and water components; the oil can be sold as a by-product or further processed through hydrogenation, while the water can be recycled in the gas-water system. The residue (dust) can be used as fuel in the accompanying boilers, and due to its small quantity, it has almost no impact ；

This approach can draw on the methods used by traditional oil refining workshops in Shandong: the tar residue is subjected to closed dry distillation, and evaporation separation is achieved by taking advantage of the different boiling points of water and various hydrocarbons. During the heating phase, water is released at temperatures below 200°C, while oil is obtained at higher temperatures. The steam and oil gases are then cooled, followed by oil-water separation, which yields a relatively satisfactory product. The oil can be sold as a product, while the water is returned to the system. Once the temperature stops rising due to continued heating, the heating is ceased; the remaining substance condenses into semi-coke, which can be sold as fuel or reused in boilers

The most primitive methods are inefficient and not environmentally friendly; I vaguely remember the crude oil refining plant that was located nearby when I was a child

I mean to draw on those methods, not to copy them outright. The environmental protection systems in modern coal chemical enterprises are far superior to those in small-scale workshops; the heat source for processing can be the combustion exhaust gases from chemical plants (flaring is also a form of combustion), electromagnetic heaters, etc. The wastewater generated can be safely discharged into the gas water treatment system designed for Lurgi reactors, and the solid residue produced is semi-coke, which can be reused in the reactors

At present, most enterprises in the country adopt two approaches: 1. Treat it as hazardous waste and contact companies with the necessary qualifications to handle it； 2. Add a centrifuge to separate the dust-containing tar; the separated tar is sold externally, while the tar residue is returned to the furnace for reduction treatment.