ProSimTechs PROCESS SIMULATION TECHNICS

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Barnard Albert Chandler
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1 PROCESS SIMULATION TECHNICS Rigorous Process Simulation Services for the Vegetable oils & Fats refining industry (Degumming - Neutralising Bleaching Deodorising/Physical Refining)

Deodorising and Physical Refining Process The Deodorising process Deodorising is by far the most energy consuming stage along the overall vegetable oil refining process.

Acid Degummin g Neutralisin g Bleaching What we want to get from a Deodoriser? Deodorisin g Quality To remove FFAs? To remove peroxides, aldehydes and ketones?

2 Deodorising and Physical Refining Process The Deodorising process Deodorising is by far the most energy consuming stage along the overall vegetable oil refining process. On the other hand, the last overall refining stage along the vegetable oil refining process. Also, it is a critical process in terms of the key quality parameters of final oil. Acid Degummin g Neutralisin g Bleaching What we want to get from a Deodoriser? Deodorisin g Quality To remove FFAs? To remove peroxides, aldehydes and ketones? What about the quality of the outlet streams? FATTY ACID Do we have a given target of tocopherol concentration in final oil? α-tocoferol Do we have the same for the distillates? Process conditions Type of Process But also to use steam as less as possible To minimize the energy involved Lab results Process condition s Process Vegetabl e oil Equipmen t To reduce the waste water Are a given set of deodorising conditions the same from a deodoriser and another? What if the quality at the oil inlet changes, how impacts on oil outlet and distillates? Do I have to change the deodorising conditions (temp, sparge steam)? Which one first and what would be the new value for each? 2

3 Do all deodorisers have the same performance? The Deodorising/Physical Refining Process Unit is one the economic heart of today s refinery. Small increases in yield can bring significant gains in productivity and revenues. Rigoruos process simulation studies have diagnosed operating problems and helped improve the performance of all major components of Deodorisers. Each project is customized to provide the information needed to optimize or troubleshoot your specific process. All testing is performed while the unit is online and will not interfere with normal unit operations or production scheduling. Data collected can be used to identify operating parameter changes to improve unit productivity, or gauge the accuracy of process modeling and simulation. A typical study employs a rigorous, accurate and customized model of the process taking into account the characteristics of the oil, the flowsheet and the equipment (Deodoriser). The starting information for the complete study is the actual information managed by the plant, for example: Capacity of processing Vegetable oil inlet-outlet composition Distillate composition Flowsheet (P&IDs or PFDs) and equipment characteristics. Current process conditions 3

Modelling and Process Simulation Process modelling is the activity of building a mathematical model of the process by describing its fundamental physical and chemical relationships, by means of

4 Modelling and Process Simulation Process modelling is the activity of building a mathematical model of the process by describing its fundamental physical and chemical relationships, by means of equations. Process simulation is one of the activities that one can perform with that process model, using an appropriate mathematical method to solve it. Process modeling and simulation are used to describe a physico-chemical process as a set of physic-chemical equations in order to perform all the calculations involved in it, in a powerful, accurate, reliable, quick way. SCREEN SHOT OF PROCESS SIMULATION OF A DEODORISING A point during the process of building the model of the vegetable refining process, is to select the appropriate models for each main parts of simulation model: Thermodynamic models: the fatty compounds requires a very specific thermodynamic model, more over considering Unit Operations with liquid-vapor equilibrium (LVE) processes. Unit operations models rigorous: most of the key process equipments are quite particular and non std designs (deodorising trays, packed columns, scrubbers). Compounds (basic data and temperature dependent properties): quite complex molecules, a few info available, predictive approach is required. 4

5 Study case: Soybean oil in Physical Refining /Deodorising + Double Scrubber Relevant information for the Modelling Equipment Type and general dimensions of the main equipments Heat exchange areas Process conditions Oil inlet temperature (ºC) Final heating temperature (ºC) Temperatures in heat recovery stages Oil outlet temperature (design) Vacuum at suction (mbar) Final heating temperature (ºC) Sparge steam distribution (Kg/h, or Kg/Tn) Motive steam (Kg/h each stage) Condensing temperature Vegetable oil inlet composition FFA (%) Tocopherol (ppm) DAG (%) MAG (%) Water (%) Sterols (%) Relevant information for validation of first simulation run Vegetable oil outlet composition FFA (%) Tocopherol (ppm) DAG (%) MAG (%) Water (%) Sterols (%) Distillate/s composition FFA (%) Tocopherol (%) DAG (%) MAG (%) Sterols (%) 5

6 Study case: Soybean oil in Physical Refining /Deodorising + Double Scrubber Objectives Modelling of the process Simulation of a given scenario in terms of process conditions and oil inlet quality Validation of the modelling against plant Sensitivity studies and optimisation To analyse sensitivity variables of Tocopherol scrubber To compare tocopherol concentration vs distillate amount Piping and instrumentation diagram (P&ID) From the real P&Id of the plant Vacuum system A flowsheet of the process with the main streams is then built, in order to be considered during the construction of the simulation model of the process Combustion gas Natural gas High pressure boiler Cold Scrubbing Hot Scrubbing Final heating FAD collecting tank FAD Cooler FAD circulating pump Cooling water pump CWS CWR FAD (FFA enriched distillate) CWS Stripping Degummed bleached oil Deareator tank TOD collecting tank TOD Cooler Cooling water pump CWR TOD (Toco enriched distillate) Deodoriser TOD circulating pump Superheater Sparging steam Inlet oil pump Economiser Final cooler CWS Refined palm oil CWR Outlet oil pump Degummed oil Degummed oil 6

7 Simplified Process Diagram + Relevant process information Introduction - Base case (current situation) was modelled and simulated. Tocopherol concentration in tocopherol enriched distillate (TOD), under current conditions, is around 12 % in weight. Objective - We want to find an optimum point for both tocopherol concentration in TOD distillate and drawn TOD distillate. Sensitivity analysis - To choose those critical process variables as independent variables - To set up the working value range of each variable - To plot results and to analyse the figures 7

Sensitivity analysis Tocopherol concentration in TOD In these 2 graphs, it is shown the influence of stripping steam and condensing temperature on the tocopherol concentration of the distillate drawn

8 Sensitivity analysis Tocopherol concentration in TOD In these 2 graphs, it is shown the influence of stripping steam and condensing temperature on the tocopherol concentration of the distillate drawn from first scrubbing stage (Hot Scrubber). The rest of the process conditions are kept constant. What is taking place is on one hand, as the sparging steam increases, the amount distilled of tocopherols and other volatile compounds also increase. On the other hand, increasing the condensing temperature in hot scrubber, the tocopherol concentration begins to rise up to a given value ( a max optimum value), then from this point the tocopherol concentration falls down, as the temperature continues increasing. Basically, what is happening is that along the first part of the curve, most of the lower vapor pressure compounds are condensed with also a given fraction of fatty acids (higher vapor pressure compounds), as the temperature increase is fesible to achieve a max tocopherol concentration, since lesser amount of fatty acids are condensed. 8

Sensitivity analysis Tocopherol concentration in TOD Now, normally to increase tocopherol concentration in tocopherol enriched distillate has a compromise: amount of drawn distillate.

9 Sensitivity analysis Tocopherol concentration in TOD Now, normally to increase tocopherol concentration in tocopherol enriched distillate has a compromise: amount of drawn distillate. So, here the objective is to optimise both tocopherol concentration jointly with the amount of distillate, with the final target of getting the maximum market price of this by-product. The effect of increasing the condensing temperature in Hot Scrubber aiming to maximise the tocopherol concentration in this distillate, has the collateral effect of reducing the amount of distillate, this is due to, as was said, now a fraction of fatty acids is not condensed in this stage, achieving the objective of increasing the tocopherol concentration. What also, a given fraction of tocopherol is not condensed in this stage as well. Which is going to be finally condensed in the final scrubbing section (cold scrubber) together with the rest of fatty acids. 9

Remarkable Facts/Summary Physical refining / Deodorising is a very complex process from the point of view of the distillation Vegetable oil is a multicompound mixture Quality of the outlet streams

10 Remarkable Facts/Summary Physical refining / Deodorising is a very complex process from the point of view of the distillation Vegetable oil is a multicompound mixture Quality of the outlet streams are very sensitive to the process conditions Also configuration and type of the equipment plays a role towards a given product quality Each plant is very particular in terms of equipment configuration, oil quality and process conditions and target Modelling and Simulation is an optimum and very valuable tool to predict and analyse different scenarios and see what if The information from a simulation run, sensitivity analysis and global optimisation allows to have an in-depth knowledge on our process, then to make the appropriate decision-making. There is a new point of view to analyze your processes. Let us exchange ideas. info@prosimtechs.com 10

Deodorisation and Physical Refining of Fats

Deodorisation and Physical Refining of Fats Ray Cook Ebortec Ltd. York, UK. www.ebortec.co.uk 1890 s Population explosion in USA and Europe fuels demand for butter substitutes Simple boiling methods adopted