Process industries need to be able to adapt to the fast changing market in order to meet consumer demands. Pipeless batch plants are being developed and implemented to improve flexibility to meet this requirement. However, their efficiency greatly depends on the generation of feasible production schedules. This paper proposes a general constraint model to solve this kind of scheduling problem for pipeless batch plants. In this model, constraints on resource allocation, activity precedence, time bound and safety issues are considered. A computer system, BPS, based on the constraint model and the search algorithm used in BPS are also presented. A case study is described to demonstrate the applicability of the proposed approach.