A study of the applicability of a straw-fired batch boiler as a heat source for a small-scale cogeneration unit

Abstract

Straw-fired batch boilers, due to their relatively simple structure and low operating costs, are an excellent source of heat for a wide range of applications. A concept prototype of a cogeneration system with a straw-fired batch boiler was developed. The basic assumptions were based on the principles of the Rankine Cycle and the Organic Rankine Cycle systems with certain design modifications. Using the prototype design of a system that collects high-temperature heat from the boiler, studies were performed. The studies involved an analysis of the flue gas temperature distribution in the area of the oil exchanger, a comparison of the instantaneous power of the boiler's water and oil circuits for different modes of operation, as well as an analysis of the flue gas. In the proposed system configuration where the electricity production supplements heat generation, the power in the oil circuit may be maintained at a constant level of approx. 20-30 kW. This is possible provided that an automatic fuel supply system is applied. Assuming that the efficiency of the electricity generation system is not less than 10%, it will be possible to generate 2-3 kW of electricity. This value will be sufficient, for an on-site operation of the boiler.