Discarded refuse can be used as a source of energy. Hitachi Zosen proposes that refuse be a valuable resource to be efficiently used. Refuse incineration also satisfies the pressing need of energy recovery and utilization by economic conversion of the combustion heat into other forms of energy, such as steam and electricity. The generated electricity covers the plant's own power requirements. Any excess power can be supplied to the public utility grid.

Both in- and outside of Japan, Hitachi Zosen has built over 40 plants with electric power generators that use municipal refuse. In addition, the energy recovered in the form of heat is utilized directly to heat the plant and to supply hot water, as well as supplying heat to nearby homes and community facilities such as swimming pools, botanical gardens, care homes and meeting places.

[Description]

Electric power produced by refuse depends on the heating value of refuse proper and steam conditions of turbine. High pressure and high temperature of inlet steam, and low pressure of exhaust steam can generate power more efficiently. The exhaust pressure of condensing type turbine is vacuum . It needs a large steam condenser, but has a high efficiency. The exhaust steam of back pressure type turbine has a positive pressure and can be used successively for other application.

POWER PRODUCTION FROM ONE TON OF REFUSE

ENERGY RECOVERY AND UTILIZATION

A higher steam temperature leads to a higher efficiency of steam turbine. It, however, causes the high-temperature corrosion of superheater tubes because of flue gas property. In order to solve this problem, the following two ways are applied:

- anticorrosion material of superheater tubes and proper design of boiler 
- resuperheat of steam from incinerator boiler by fossil fuel or gas-turbine 
  exhaust gas

[Application]

The followings are two examples of efficient power generation of refuse incineration.

TAKAHAMA PLANT
   Combined with Gas Turbine 
Incineration Capacity:  150t/d X 3
Steam Turbine:  10,500 kW
Gas Turbine  :  17,500 kW

SAITAMA-TOBU PLANT 
   with High Temp.Superheater 
Incineration Capacity:  200t/d X 4 
Steam Turbine:  12,000 kW X 2