Adding sodium lignosulfonate in the preparation of coal-water slurry can improve mill output, maintain the normal condition of the slurry system, reduce slurry power consumption, increase the concentration of coal-water slurry, reduce oxygen consumption and coal consumption in the gasification process, increase the efficiency of cold gas, and reduce the viscosity of coal-water slurry and achieve a certain stability and fluidity. As a dispersant, lignin sulfonate improves the dispersing ability of coal, increases the heating rate and utilization rate of coal, greatly reduces the coal content in fly ash, reduces bridging and caking, and improves furnace life.
The so-called coal water slurry refers to a slurry made of 70% coal powder, 29% water and 1% chemical additives after stirring. It is a fluid fuel that can be pumped and atomized like fuel oil. It can be transported and stored over long distances, and its calorific value is half that of fuel oil. It has been used to transform ordinary oil-fired boilers, cyclone furnaces, and even chain-type fast-loading furnaces. Due to the simple processing method of coal water slurry, compared with coal gasification or liquefaction, the investment is much less and the cost is also low. Therefore, since it was developed in the mid-1970s, it has been valued by many countries. my country is a big coal producing country. We have invested more in this area and accumulated rich experience. Now we can even make high-concentration coal-water slurry from the coal powder produced by coal washing.
The chemical additives of coal water slurry actually include dispersants, stabilizers, defoamers and corrosive agents, but generally refer to two categories of dispersants and stabilizers. The role of additives:
On the one hand, coal powder can be uniformly dispersed in the water medium in the form of individual particles, and at the same time, it is required to form a layer of hydration film on the surface of the particles, so that the coal-water slurry has a certain viscosity and fluidity; on the other hand, it is necessary to make the water The coal slurry has certain stability, which prevents the precipitation and crusting of pulverized coal particles. The three elements that high-quality coal water slurry should have are high concentration, long stable period and good fluidity. The key to preparing high-quality coal water slurry is
Two: First, the coal quality is good, and the coal powder particle size distribution is uniform; second, the chemical additives are good. Generally speaking, the coal quality and coal powder particle size are relatively stable, and it is the additives that really work.
In order to reduce the production cost of coal water slurry, some countries have attached great importance to the research and application of humic acid and lignin as additives in recent years. They can produce additive packages that function as both dispersants and stabilizers.