Black liquor solids measurement is key to plant operation, influencing the economics of the pulping process, as well as the environmental load of the mill. Careful monitoring of solids concentration at various stages of black liquor production is critical to avoid operational problems. Understanding the physical properties of black liquor at each stage assists in anticipating it’s down-stream consistency and provides valuable insight toward higher mill efficiency.
Black liquor is a mixture of water, various chemicals and very fine organics. It’s solids concentration is defined as the mass ratio of dried black liquor to wet black liquor, prior to drying. When water content is too high, black liquor presents a negative net heating value. This means it may only have enough heat energy from organics combustion to evaporate the water it contains. By using a high solids concentration in the black liquor, the thermal efficiency of the recovery boiler is greatly improved.
Analysis of black liquor solids concentration is conducted periodically throughout the mill, from the washers, through the evaporator, to the ring header. The most common means of doing this is by collecting samples from the various points in the processing line, and then taking the samples to the laboratory for gravimetric analysis. Although this technique is simple and highly reliable, it is also very time consuming (taking many hours or even days) because of sample collection, preparation, and testing.
A far speedier alternative is Electron Machine Corporation's DSA E-Scan™ Black Liquor Analyzer. This device provides solids measurements in just 10 seconds, with accuracy and repeatability every bit as good as gravimetric methods. While the cost-benefit analysis of deploying the DSA E-Scan™ will vary from paper mill to paper mill, there's no denying the magnitude of time savings the DSA E-Scan™ provides will significantly reduce cost.
Electron Machine has worked for years to develop and improve the speed and the accuracy of both inline and offline equipment. This continual improvement for black liquor solids measurement allows Electron Machine the ability to offer equipment that will greatly increase the speed in which these studies are conducted.