Alkali concentration is a key process parameter that must be monitored at multiple locations within the kraft process including alkali concentration in the digester, residual black liquor in pulp wash stages, alkali concentration in causticizer tanks and green liquor alkali concentration. Alkali concentration is monitored using conductivity sensors instead of pH sensors due to the high process temperatures and thick pulp. Rosemount™ toroidal conductivity sensors are recommended for all applications within the kraft process due to their proven reliability with minimum maintenance. Toroidal sensors offer greater resistance to the effects of coating and corrosion than contacting conductivity sensors which is important due to the pulp and lime solids present in the process as well as the corrosive nature of the liquor used to delignify the wood.
The Rosemount 1058 Dual Channel Transmitter provides confident liquid analysis measurement in a wide range of industrial, municipal and commercial applications. It is a 4-wire powered device that provides multi-parameter liquid analysis for digital and analog sensors, including inputs from pH/ORP sensors, ISE, flow, current, conductivity sensors (contacting and toroidal), turbidity sensors and amperometric sensors (dissolved oxygen, chlorine and ozone).