K-Patents Oy - pulp

K-Patents Digital Divert Control System DD-01 Back to overview of Pulp & paper
	Brochure Product manual How K-Patents DD-01 is built to conform to the BRLBAC Recommendations
K-Patents Digital Divert Control System DD-01 complies strictly with all recommendations of the Black Liquor Recovery Boiler Advisory Committee (BLRBAC). The DD-01 system includes two Process refractometer sensors PR-01-S-LPH in the main black liquor line, and two Indicating transmitters and a Divert control unit in an integrated panel. K-Patents Process refractometer sensors are installed with an Isolation valve HIMP that allows for safe and easy insertion and retraction of the refractometers under full operating pressure without having to valve off the liquor piping or having to shut down the process. The Isolation valve contains a steam wash system for automatic prism cleaning. Each refractometer is a completely independent measurement system. Each system sends a separate output signal, which can be used by the control system or DCS. The key features: Completely digital system from the sensors to the transmitters: system is completely microprocessor controlled and all analog circuitry has been eliminated. The digital signal transmission and microprocessor implemented diagnostics ensure error free operation. The system eliminates false alarms, because it reacts only when the level of solids truly falls below the safe limit. Using K-Patents DD-01 costly process disturbances resulting from unwarranted divert actions can be avoided. Easy to operate and clear multi-diagnostic messages. K-Patents isolation and retractor allow for safe and easy insertion and removal of the refractometer sensor under full process pressure. Accidental opening or closing of the isolation ball valve is prevented. Why a Digital Divert System? Feeding low concentrations of black liquor solids to a kraft chemical recovery boiler burner can cause a steam explosion. A digital divert control system is required to ensure safe operation. BLRBAC recommends standards for safe firing of black liquor and suggests using an automatic black liquor divert control system to ensure that weak liquor is not fed into the boiler. BLRBAC requires that if the black liquor concentration falls below 58%, the system shall give an audible alarm signal, and go to a diversion function to direct the black liquor flow to by-pass the boiler. A concentration value of 60% shall give an audible alarm to notify the users about the low concentration. Furthermore, the control unit shall check that the difference between the two individual refractometer signals does not exceed 2%. These close tolerances require digital circuitry which eliminates drift.