Nonstandard analysis of waste heat power generation in cement kiln

Date: 2019-06-26 Views:

Low-temperature waste heat generation technology of cement kiln has been widely used in China, and the technology has been quite mature.Some waste heat power stations in China produce more electricity than the designed value, and waste heat resources are fully utilized.But there is still a considerable proportion of cement kiln waste heat power generation can not reach the design value.There are many reasons why low-temperature waste heat power generation cannot reach the design value. I have made the following analysis.

1. The actual available residual heat smoke volume of cement kiln is low

1.1 smoke volume of SP furnace inlet is relatively small

The raw material mill dry air should use SP furnace outlet exhaust gas, its temperature should meet the needs of raw material drying temperature.In the practical operation of waste heat power station, if the exhaust gas temperature at the outlet of boiler is lower than the design value or the pressure difference at the inlet and outlet of boiler is obviously smaller, the amount of smoke entering the boiler may be too small.The main reason why the input smoke of sp furnace did not reach the design value was that the boiler bypass valve was not completely closed.In operation, the bypass valve can adjust the temperature of the smoke entering the raw material at any time. When the boiler bypass valve is opened, part of the smoke directly enters the original technical system of cement kiln without passing through the boiler heat exchange, which is the actual smoke entering the boiler

1.2 the inlet smoke volume of AQC furnace is relatively small

The exhaust gas from AQC furnace is not used in production.In the design of waste heat boiler, its smoke exhaust temperature is generally about 100℃.At the same time, because the heating surface of AQC furnace cannot be fully utilized, the feed water temperature of SP furnace is low, affecting the steam production of AQC furnace and SP furnace.

2 the actual waste heat flue gas temperature of cement kiln is low

2.1 low temperature of flue gas entering SP furnace

The smoke temperature at the inlet of SP furnace is mainly determined by the exit temperature of C1 level of cement kiln preheater. According to the design specification of cement factory, the smoke temperature at the inlet of SP furnace should not be higher than 320℃ when using the five-level preheater, and the waste heat power generation design is 320℃. In actual operation, some cement kilns are below 310℃, resulting in low waste heat utilization temperature.

2.2 low temperature entering AQC furnace

The afterwind temperature of the grate at the head of cement kiln is 250 ~ 300℃. When the afterheat power generation is designed, the grate is disgeled from the front of the grate, and the exhaust gas at 380℃ is filtered to remove large particles and dust, and then it is transferred to the AQC furnace.It is usually required that "thin material is burned quickly" in the original cement kiln. If the thickness of the grate cooler layer is not enough, the heat storage and heating of the material layer through the cooling air will be insufficient, which will lead to the lower temperature of the kiln head exhaust gas.

Waste heat power generation is the best utilization of resources, rational utilization can increase the profit of cement production line.

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