A versatile resource for industry
Sodium sulfate (Na₂SO₄) is a valuable resource. It is synthetically produced, obtained from natural deposits, or occurs as a by-product in many chemical processes, for example in viscose production or flue gas desulfurization. Na₂SO₄ has a wide variety of applications in the detergent, paper and pulp industry as well as in the chemical industry and fabric dye manufacturing. Recovering this salt is interesting from an economic perspective and typically involves concentration in evaporators.
Crystallization as a cost factor
The technical challenge of concentration is the unique dissolution behavior of sodium sulfate: It exhibits inverse solubility and crystallizes, particularly at high temperatures, in the initial effects of an MEE evaporator. In conventional heat exchangers, this produces hard insulating deposits (scaling) which can – in a worst-case scenario - completely block the tubes. This results in rapidly decreasing heat transfer, lower evaporator performance, and cost-intensive plant shutdowns for cleaning.
Continuous heat transfer without shutdowns
TAPROGGE Products
The self-cleaning Klaren Heat Exchanger prevents scaling during ongoing operation. A fluidized bed of fine particles circulates in the evaporator tubes and continuously cleans the tube inner wall. The crystallizing salt particles are removed immediately before they can form a solid layer. This keeps the heat transfer surfaces permanently free from deposits and the heat transfer rate remains high.
The result
The evaporator's performance remains stable, the energy efficiency stays at the maximum level, and cleaning-induced shutdowns are prevented. This allows for continuous operation, increases the sodium sulfate recovery rate, and reduces the operational expenditures (OPEX) in the long term. At the same time, the solution can be seamlessly integrated into new and existing plants (retrofit). This also applies to multiple effect evaporators (MEE) and mechanical vapor recompression (MVR) plants.
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