The report describes a lime spray dryer/baghouse (FORTRAN) computer model that simulates SO2 removal and permits study of related impacts on design and economics as functions of design parameters and operating conditions for coal-fired electric generating units. The model allows evaluation of several potential utility design and operating conditions for quick comparative costs of lime spray drying options on a common cost basis. Two significant limitations of the model are: the SO2 removal is based on operating parameter ranges and results developed for low-sulfur coal applications (data on high-sulfur coal applications are lacking) and only an overall system SO2 removal efficiency (without separate spray dryer and baghouse components) is calculated. The model projections using medium (2% sulfur) and high sulfur coal may be in error, with error increasing with increasing coal sulfur content. Means of overcoming these limitations are proposed. The users manual describes the model and instructions for its use, required input data are detailed, and sample computer runs with output are provided to guide users in identifying applications.