Method and decomposition stove for preparing lime in suspended state with wood coal as fuel

Abstract

The invention relates to a method for producing lime that lignite powder is mixed with limestone powder that is heated by a suspension pre-heating system to be burned in a reversed U-shaped decomposition furnace, and calcium carbonate is decomposed inside the decomposition furnace, and the lime is cooled by a suspension cooling system. 70 percent of the lignite powder is sprayed into a decomposition furnace cylinder 15 through the head part of the decomposition furnace; after being heated by the suspension pre-heating system 1-11, the limestone powder is fed into the decomposition furnace from a feeding pipe 12. 30 percent of the lignite powder is sprayed into the decomposition furnace cylinder 19 from the mid-part lignite-spraying pipe 18, so as to maintain the temperature at 900 DEG C. After the lime is cooled by the suspension cooling system 22-33, the lime is collected by a whirlwind dust collector 33, and enters into a lime bin 35. The reversed U-shaped decomposition furnace is mainly composed of a feeding pipe 12, a head-part lignite-spraying pie 13, an inlet-end cylinder 15, a reversed U-shaped connection pipe 16, a mid-part lignite-spraying pipe 18 and an outlet-end cylinder 19. The diameter of the cylinder 19 is larger than that of the cylinder 15, so as to prolong the remaining time of the material and to reduce the resistant force of the system.

Description

Technical field: [0001] The invention relates to a method for producing lime by using lignite as fuel, heating limestone powder in suspension preheating, mixing coal powder and limestone powder in a decomposition furnace and burning lime in a suspension cooling system. Calcium carbonate decomposes at about 900°C, and the generated lime has a loose and porous structure, good activity, and is conducive to reacting with other substances; the amount of NOX formed is small. Among them, about 70% of the lignite powder is injected from the head of the calciner, and 30% of the coal powder is injected from the middle of the calciner to keep the temperature of the calciner uniform and stable. The diameter of the cylinder at the outlet end of the calciner is larger than that at the inlet end, which can prolong the residence time of materials and reduce system resistance. Background technique: [0002] The current method of producing lime is to pile up lumpy limestone in an earthen kil...

AI Technical Summary

Problems solved by technology

Its disadvantages are: 1. Low degree of production automation, low production efficiency, and scattered production concentration

2. Limestone is heated and decomposed in a block, the heat transfer and mass transfer speed is slow, the heating and decomposition time is long, the production requires high temperature, long holding time, low heat utilization efficiency, and high heat consumption; the generated S0???2 Large amount of NOX and serious environmental pollution; 3. High production temperature is required, which is not conducive to the utilization of fuels with low calorific value and low combustion temperature such as lignite

4. The incomplete combustion of fuel is serious, the amount of CO formed is large, and the waste of fuel is large

5. The formation temperature is high, the structure is compact, the activity is poor, the quality is unstable, and the slag is relatively large when used, which is a serious waste, which is not conducive to the utilization in industry;

The temperature of the gas entering the calciner from the cyclone cooling system is about 650°C, which is lower than the ignition point of bituminous coal at 870°C, which is not conducive to the complete combustion of bituminous coal.

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