Energy balances pyrolysis process

The second case study corresponds to an existing pyrolysis reactor also located at the Orica Botany Site in Sydney, Australia. This example demonstrates the usefulness of simplified mass and energy balances in data reconciliation. Both linear and nonlinear reconciliation techniques are used, as well as the strategy for joint parameter estimation and data reconciliation. Furthermore, the use of sequential processing of information for identifying inconsistencies in the operation of the furnace is discussed. 

In the second example, that of an industrial pyrolysis reactor, simplified material and energy balances were used to analyze the performance of the process. In this example, linear and nonlinear reconciliation techniques were used. A strategy for joint parameter estimation and data reconciliation was implemented for the evaluation of the overall heat transfer coefficient. The usefulness of sequential processing of the information for identifying inconsistencies in the operation of the furnace was further demonstrated. 

Technoeconomic Assessment. Although the use of fractionated pyrolysis oils as adhesives is still in the early phases of development, a technological assessment of the process was made using the best projections available for the yields and operating conditions. A detailed process flowsheet was made with mass and energy balances around each major piece of equipment. The equipment was sized and then valuated using data from the literature. The costs... 

Pyrolysis oil is produced at 380 kg from 1000 kg of waste plastics. The oil for sale externally amounts to 125 kg, with 255 kg self-consumed as process fuel. After operational, improvements these values improved remarkably, as shown in the following energy balance. 

These conditions lend themselves to simple and inexpensive system design. Pyrolysis can be an energy efficient process yielding a favorable energy balance because the process uses only a fraction of the energy contained in the wood. 

The plant is controlled by a process computer (ABB-Hartmann and Braun) and equipped with numerous data-collecting instruments. Surveillance is carried out by continuous analysis of the room air as well as by explosion-limit controls. The pyrolysis gas is analyzed automatically by a gas chromatograph. All data obtained are registered to enable calculation of energy and mass balances. Some basic components are continuously monitored by infrared spectroscopy, i.e. ethylene in the pyrolysis gas, sulphur dioxide and oxygen in the exhaust gas. 

This work is part of the smart enterprise division in Tumut Visy Pulp and Paper, and addresses the advanced control and operation of the mill. In this context, a robust dynamic model is developed for the recovery boiler, and validated over a wide range of operating conditions. In the steady state case, energy and mass balances were carried out over the different sections of the process. In the dynamic case, initially, heat and mass transfer across the bed are coupled with moisture evaporation, black liquor pyrolysis, char combustion and gasification, gas-phase. The influence of model parameters kinetic constants and operational variables on process dynamics are studied by numerical simulation. The model was developed/implemented in a Visual C++ environment. 

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