The main characteristics of the papermaking black liquor spray dryer are: the liquid concentration is 40% to 55%, and the processing volume is larger to a certain extent, a set of 10,000 tons/year scale paper mills, the black liquor processing capacity is greater than 3 t/h; containing more ash, the so-called silicon interference, black liquor without desugar treatment, containing a lot of sodium saccharate and its derivatives, containing many small staple fibers; high viscosity at room temperature, lignin spontaneous combustion Sex.
The papermaking black liquor spray dryer is effective in preheating the concentrated black liquor to 70°C or more during the operation, so that the viscosity of the solution can be effectively reduced to a certain extent, and the rotation is mainly adopted in the production. Disc type nebulizer to avoid clogging of orifices of pressure atomizers. If air atomizers are used, the dry powder loading density is low, and atomization energy consumption increases the cost; in paper mills with power generation devices, available power stations As a heat source, steam can also be used as a heat source when dust is directly dedusted by a coal-fired hot air stove. When the air inlet temperature is higher than 280°C, the internal drying of the spray-drying tower can easily occur. Therefore, the air inlet temperature must not exceed 280°C. Feeding speed to prevent poor atomization caused by excessive feed rate and sticking to the wall, resulting in combustion.
Papermaking black liquor spray dryers to a certain extent are the most widely used processes in the process forming and drying industries. To a certain extent, the black liquor spray dryers are most suitable for producing powders, granules, or powders in solutions, emulsions, suspensions, and plasticity pastes. Bulk solid product. Therefore, when the particle size distribution, residual moisture content, bulk density, and particle shape of the finished product must meet the exact criteria. Spray drying is a very desirable process.
The black liquor spray dryer of the papermaking machine is effectively filtered and heated by the air during its operation, and effectively enters the air distributor at the top of the dryer. The hot air spirally enters into the drying chamber. The feed solution is passed through the high-speed centrifugal atomizer at the top of the tower body, and (rotated) is sprayed into very fine mist-like liquid beads, which can be dried in a short time in the cocurrent contact with hot air. The finished product is continuously output from the bottom of the drying tower and the cyclone separator, and the exhaust gas is exhausted by the fan.
The black liquor spray dryer has a fast drying speed and the surface area of the liquor is greatly increased after atomization. In a hot air stream, 95% to 98% of water can be evaporated instantaneously, and the drying time only takes ten seconds or more. The dozens of seconds are particularly suitable for the drying of heat-sensitive materials. The resulting products are spherical particles, uniform particles, good fluidity, good solubility, high product purity, and good quality.