Method for calcining limestone by using low-calorific-value fuel in double-hearth kiln

Abstract

The invention relates to a method for calcining limestone by using low-calorific-value fuel in a double-hearth kiln, which is characterized in that incomplete combustion calcination is performed in a kiln body on one side, and complete combustion calcination is performed in a second calcination area of a kiln body on the other side. The specific process is as follows: in the state (1), fuel and air are sprayed into a kiln chamber A for complete combustion, and flue gas enters a kiln chamber B for preheating materials; in the state (2), fuel and 3-30 (v)% of the required amount of air injected into the kiln chamber A are incompletely combusted, and burning is conducted in a second calcining area of the kiln chamber B, and the material is continuously calcined; in the state (3), fuel and air are sprayed into the kiln chamber B to be completely combusted, and flue gas enters the kiln chamber A to preheat the materials; and in the state (4), fuel and 3-30 (v)% of air are injected into the kiln chamber B for incomplete combustion, combustion is conducted in the second calcining area of the kiln chamber A, and the material is continuously calcined. By means of the second calcining area and time-controlled segmented calcining, the limestone calcining process of the double-hearth kiln is optimized, the calcining effect is improved, low-calorific-value fuel is fully utilized, high-quality fuel is saved, and the quality of calcined products is improved.

Description

technical field [0001] The invention belongs to the technical field of chemical building material production, and relates to an industrial furnace, in particular to a method for calcining limestone with a low calorific value fuel in a double-chamber kiln. Background technique [0002] Double-chamber kiln is also called double-chamber parallel-flow regenerative lime kiln. The fuel enters from the upper end of the calcination belt and flows in parallel with the raw materials. Since the fuel is injected from the upper part of the calcination zone, the raw material can absorb most of the heat released by the fuel here. Another important feature of double-chamber kiln is heat storage, which uses heat storage to preheat part of the combustion air. The thermal characteristics of co-current calcination and counter-current heat storage determine that the double-chamber kiln has high thermal efficiency, and its thermal energy consumption is the lowest among all types of lime kilns, i...

AI Technical Summary

Problems solved by technology

Limestone cannot be decomposed if the combustion of low calorific value fuel cannot reach the required temperature; or if the temperature is low, the decomposition of limestone will not be complete, resulting in problems such as raw burning and poor quality of lime products

In the production process of metallurgical enterprises, a large amount of blast furnace gas is produced, which is a valuable fuel resource. The calorific value of blast furnace gas is 3000~3400kJ / Nm 3 . Due to its low calorific value, it cannot be directly used for calcining limestone, so that a large amount of low calorific value fuel cannot be used fully utilized

However, the production of lime also requires the purchase of fuels with high calorific value, resulting in waste of resources and affecting economic benefits

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