OCR Text |
Show Thus, the operational store serves to time-average the temperature fluctuations of the source. The peak store is used to store energy during time of slack demand and provide additional energy to meet demand peaks. During the charging mode valve 1 is closed; hence, all fume gases are directed to the peaking storage unit. Valve 2 is closed and fume flows are circulated to the baghouse and then to the atmosphere by fans 9 and 10. In the discharge mode gas streams from the operational and peaking storage units combine in mixer 1 and flow to the steam generation heat exchanger. After leaving the heat exchanger the gas is again split into two streams and returned to the proper storage unit. To utilize reject energy in coke and slag cooling operations will require redesigned facilities to capture and reuse the heat. After the coking coal has been baked it is transported by rail to the quench area where water is sprayed over the hot coke. Two TES applications have been identified (17) that recover the heat contained in the hot coke charge, which is at about 1000°C. A variation of the dry cooling method (17) is shown in Fig. 6. In this proposed scheme the hot coke is dumped into a two-chamber vessel where it is cooled by non-oxidizing gases. These hot gases can then be routed through the TES unit. Since fines are contained in the reject heat gas stream, a cyclone separator is included in the design. A second approach directly transfers energy from the hot coke to the TES media (17). In this system the TES unit is the coke quenching vessel. A cover is provided to close the chamber thus starving the oxygen supply t the coke, which results in the termination of the burning reaction. A conveyor belt could be used to convey the cooling coke through several TES units, each using a different medium, to maximize energy recovery. (Fig. 7) During normal steel mill operations slag is periodically tapped off and dumped into a slag pile to cool and subsequently be used for cement making or in road construction. Since the slag is initially .it 650°C ^nd 20% of the total charge to a blast furnace Ls slag, (17), it represents a major source of potentially reusable reject heat. Handling of the slag represents a major problem in these applications. Several concepts have been proposed (17) to recover this heat (see Fig. 8 and 9). In both of the proposed systems the slag heat is transferred to the TES media via conduction. 8-10 |