Non reactive _ reactive - Chemical Process Principles (CEN...

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Chemical Process Principles (CEN 1022) Chapter 2: Material Balance CHAPTER 2 MATERIAL BALANCE 2.1 Balance Over Single / Multiple Unit Operations (Non Reactive Process) The streams leaving are the output or products stream PROCESS The streams entering are the input or feed stream In Chemical engineering, a process is an operation or series of operations that causes physical or chemical changes in a substance. Law of conservation of mass Mass can neither be created nor destroyed Total mass input = total mass output When a process operates such that there is no change in flows, pressures or other process variables with time, it is at steady state . When the process variables (temperature, pressure and etc) change with time it is described as unsteady state or transient . 2.1.1 Process Classification Batch Process – All feed goes in at one time All products comes out at one time Unsteady State/Transient Used for small scale production (small quantities of end products) Example: Baking cookies, fermentation, small scaled chemicals (pharmaceuticals) SAT 1
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Chemical Process Principles (CEN 1022) Chapter 2: Material Balance Continuous Process – Feed and product stream flows continuously Steady State (run close to) /Transient (during start up) Suitable for large production rates Example: Distillation processes Semi-batch Process – Any process that is neither batch nor continuous Example: Washing machine 2.1.2 Material Balance Equation Output Input Process 1. General Any material that enters or leaves any process system; it can be applied to the total mass of this material or to any molecular or atomic species involved in the process. Accumulation = Input + Generation - Output – Consumption Types of balances are; Differential – based on rates kg/hr, kmol/min, Ibm/hr Indicates what is happening in a system at an instant of time Integral – based on amounts Ibm, kg, kmol Indicates what is happening between two instant of time Example 1 Case of subject CEN 1022 from 1st month to last month of semester January 04 59 new students signed up [IN] 4 added (repeat) [GENERATION] 1 dropped [CONSUMPTION] No incompletes [ACCUMULATION] What is the number that finishes the course [OUT] ? Answer: 62 students SAT 2
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Chemical Process Principles (CEN 1022) Chapter 2: Material Balance 2. Special Cases i. At continuous steady state or total mass, where Accumulation = 0, therefore Input + Generation = Output + Consumption ii. If there is no chemical reaction, where Generation = 0 Consumption = 0, therefore Accumulation = Input – Output iii. If there is no flow across system boundaries (batch processes), where Input = 0 Output = 0, therefore Accumulation = Generation – Consumption 2.1.3 Material Balance Calculation When you are presented with a description of a process and asked to determine something about the process, it is essential to organize the given information in a way that is convenient for subsequent calculations.
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This note was uploaded on 05/08/2011 for the course ACCOUNTING 121210 taught by Professor Sdasdas during the Spring '10 term at Albany College of Pharmacy and Health Sciences.

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Non reactive _ reactive - Chemical Process Principles (CEN...

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