**1. Introduction**

258 Modeling and Optimization of Renewable Energy Systems

Weigt, H. (2009). Germany's wind energy: The potential for fossil capacity replacement and

2619.

cost saving. *Applied Energy*, Vol. 86, (October, 2009), pp (1857-1863), ISSN 0306-

Nitric acid plants both in AZOTY Tarnów and ANWIL SA in Włocławek are dual pressure plants which means that ammonia oxidation and heat recovery take place under a low pressure whereas absorption under a high pressure. Nevertheless, there are important differences between them in regard to pressure and construction solutions applied and the level of their exploitation. A number of design solutions were implemented which aimed at removal of equipment damage, as well as exchange of machines and equipment and provision of plant continuous operation before 2000. Most of these works were performed by companies themselves, however Fertilizers Research Institute (Instytut Nawozów Sztucznych) participated in realization of some of them. After 2000 the increase of nitric acid plant capacity in the above mentioned Works became necessary. The scope of tasks to be undertaken, the realization of which was necessary to increase plant capacity in the above mentioned Works was to be defined in the first stage. This project was realized in cooperation with Fertilizers Research Institute. Some of the accomplished tasks which allowed for the achievement of stated objectives are presented below.
