McKAY BAY REFUSE-TO-ENERGY FACILITY SPLIT-RANGE CONTROL SYSTEM

摘要

The McKay Bay Refuse-to-Energy Facility underwent a three-year retrofit program completed in 2001. The major portion of this work involved the replacement of all four combustion trains. The existing turbine generator set, rated at 22.5 MW, was retained. Each of the four boilers had a maximum continuous rating (MCR) of 62,186 lb/hr of steam; i.e., 248,744 lb/hr with all boilers in operation. The turbine generator operated at about 220,000 lb/hr (about 93% capacity), thus allowing for load swings due to fuel inconsistencies. As a result of the difference between the boiler MCR and the rate into the turbine, excess steam (over 26,000 lb/hr) was sent to an existing bypass (dump) condenser. Upon installing a new automatic governor control system for the turbine during the retrofit, the potential for providing additional control capabilities was realized. Utilizing an available second control feature on the governor control system, a major portion of the bypassed steam could be sent to the turbine via an innovative split-range control system configuration. The formerly bypassed steam was now added to the energy recovered, and had a positive effect on the net kwh/ton of waste. This paper discusses the research, design and installation of the split-range control system, as well as the economics of the project. The capital cost of this system enhancement was recovered in the first three months of operation, and the process continues to operate successfully.