INTRODUCTION Revised October 2. 1999 The material balance is the fundamental tool of chemical engineering. It is the basis for must thoroughly master its use in the formulation and solution of chemical processing problems uh the analysis and design of chemical processes. So it goes without saying that chemical engineer In chemical processing we deal with the transformation of raw materials of lower value into products of higher value and, in many, cases unwanted byproducts that must be disposed of. In addition many of these chemical compounds may be hazardous. The material balance is the chemical engineer's tool for keeping track of what is entering and leaving the process as well as what goes on internally. Without accurate material balances, it is impossible to design or operate a chemical plant safely and economically The purpose of these notes is to provide a guide to the use of material balances in chemical engineering. Why one might ask? Aren't there already enough books on the subject, books such as those by Felder and Rouseau, by Himmelblau, and by reklaitis? To answer that question we need to look briefly at the history of the problem A. Types of Material Balance Problems First let us look at the types of material balance problems that arise in chemical engineering. There are four basic types of problems (1)Flow sheet material balance models for continuous processes operating in the steady state (2) Mixing and blending material balances (3 Flow sheet material balances for non-steady state processes, either continuous or batch. and (4) Process data analysis and reconciliation A flow sheet is a schematic diagram of a process which shows at various levels of detail the equipment involved and how it is interconnected by the process piping(See, for instance Figures Il-1 and 11-2 in Chapter II). A flow sheet material balance shows the flow rates and compositions of all streams entering and leaving each item of equipment Most of the emphasis on material balance problems has continuous processes operating in the steady state. Again one might ask why. The reason is simple. Of the total tonnage of chemicals produced, the vast majority is produced using continuous steady-state processes. This includes oil refineries as well as chemical plants producing large tonnage products such as sulfuric acid, ethylene, and most of the other commodity chemicals, petrochemicals and-1- INTRODUCTION Revised October 2, 1999 The material balance is the fundamental tool of chemical engineering. It is the basis for the analysis and design of chemical processes. So it goes without saying that chemical engineers must thoroughly master its use in the formulation and solution of chemical processing problems. In chemical processing we deal with the transformation of raw materials of lower value into products of higher value and, in many, cases unwanted byproducts that must be disposed of. In addition many of these chemical compounds may be hazardous. The material balance is the chemical engineer's tool for keeping track of what is entering and leaving the process as well as what goes on internally. Without accurate material balances, it is impossible to design or operate a chemical plant safely and economically. The purpose of these notes is to provide a guide to the use of material balances in chemical engineering. Why one might ask? Aren't there already enough books on the subject, books such as those by Felder and Rouseau, by Himmelblau, and by Reklaitis? To answer that question we need to look briefly at the history of the problem. A. Types of Material Balance Problems First let us look at the types of material balance problems that arise in chemical engineering. There are four basic types of problems: (1) Flow sheet material balance models for continuous processes operating in the steady state, (2) Mixing and blending material balances, (3) Flow sheet material balances for non-steady state processes, either continuous or batch, and (4) Process data analysis and reconciliation A flow sheet is a schematic diagram of a process which shows at various levels of detail the equipment involved and how it is interconnected by the process piping (See, for instance Figures II-1 and II-2 in Chapter II). A flow sheet material balance shows the flow rates and compositions of all streams entering and leaving each item of equipment. Most of the emphasis on material balance problems has been on continuous processes operating in the steady state. Again one might ask why. The reason is simple. Of the total tonnage of chemicals produced, the vast majority is produced using continuous steady-state processes. This includes oil refineries as well as chemical plants producing large tonnage products such as sulfuric acid, ethylene, and most of the other commodity chemicals, petrochemicals and