Apparatus for drying coal using reheat steam

Abstract

The present comprises: a first coal dryer; a second coal dryer; and a third dryer, by removing moisture remaining inside and outside of coal, which is used for fueling thermal power plants, in the multiple coal dryers using reheat steam at a high temperature, incomplete combustion of coal can be prevented, thereby enhancing heat capacity of the coal, minimizing release of pollutants, preventing corrosion and enhancing the durability of a system, reducing the rate of spontaneous combustion due to reduced moisture, improving crushing efficiency of a coal pulverizer and heat distribution of a power boiler when coal is combusted, resolving the issue of clogging of a moving pathway when coal is transported, and improving coal supply stability by increasing utilization of low-quality coal for which demand is low. Furthermore, the following advantages can be provided: use of low heat capacity coal which is more affordable than high heat capacity coal; savings in fuel cost and manufacturing cost by reduced coal importation; reduction of waste, pollutants, and carbon dioxide generated from exhaust gas by relative reduction of coal consumption, and the advantages of replacement of foreign technology and exportation of equipment to foreign markets could be anticipated.

Description

TECHNICAL FIELD[0001]The present invention relates to an apparatus for drying a coal using a reheat steam, and more particularly, to a coal drying apparatus equipped with a multistage dryer that removes water contained in the coal used as a fuel for thermal power plants by jetting the reheat steam.BACKGROUND ART[0002]In general, in a thermal power plant that generates power using the coal as a fuel, coal of about 180 tons / hr per 500 MW is combusted, and the coal equivalent to about 37 tons per differentiator is supplied to a boiler. In the thermal power plant of 500 MW that uses the coal, approximately six coal yards having capacity of approximately 500 tons are installed, the normal supply of coal is performed in five of them, and the remaining one is operated as a coal yard that preliminarily stores the coal capable of being used for a certain period of time.[0003]Further, in the thermal power plant that generates power using the coal as a fuel, a standard thermal power design cri...

AI Technical Summary

Benefits of technology

[0018]According to the present invention, by removing the moisture remaining on the inside and the outside of the coal as the fuel used in the thermal power plant using the high-temperature reheat steam in a multi-stage coal dryer to prevent incomplete combustion, a calorific value of the coal is improved, the discharge of the pollutants is minimized, corrosion of the system is prevented, the durability is improved, the natural ignition rate with a decrease in moisture is reduced, the grinding efficiency of the coal differentiator and the heat distribution of the power boiler during combustion of coal are improved, it is possible to eliminate the clogging phenomenon of the path at the time of transportation of coal, and it is possible to improve the stability of the coal supply by enhancing the utilization rate of the low-grade coal of the low-demand. Also, it is possible to use a low calorific coal of a price cheaper than a high-calorific coal, to reduce the fuel cost and the original cost due to a decrease in amount of coal import, and to relatively reduce the coal consumption, thereby being able to achieve an effect of reducing the emissions of waste and contaminating substances generated from the combustion gas and reducing carbon dioxide, and it is possible to expect a substitution effect of overseas techniques and an effect such as an overseas export of equipment.

Problems solved by technology

When the standard thermal power combustion limit is 5,400 Kcal / Kg and a heating value of the used coal is low, a decrease in the power generation amount and an increase in the fuel consumption are expected due to a decline in the combustion efficiency.

Furthermore, when using the sub-bituminous coal that is a high-moisture and low-calorific coal, since the moisture content is higher than the design criteria, a conveyance system for transport the coal is not smooth, and when grinding the coal using a differentiator, a decline in the efficiency, a decline in the combustion efficiency due to some incomplete combustion, a deviation of a heat distribution generated in the boiler, and operation in an abnormal state also occur.

In addition, in the face of safety issues due to expectation of global economic recovery, and destruction of the nuclear power plant caused by Japanese huge earthquake, the preference of the thermal power plant increases, and demand and price of coal seems to consistently rise.

Since the environment of the global coal market changes from the consumer to the provider, stable supply and demand of coal are difficult, a production volume of the high calorific coal is expected to be maintained at current levels, and thus, an imbalance of coal supply and demand is expected.

Although the low-calorific coal is about 47% among the total deposits of the world's coal and its deposits are much, since there are problems of a low calorific value, a high moisture content and a combustion failure during combustion, and the high moisture low calorific coal has a difficulty in complete combustion, it is ignored in the market.

Until recent years, worldwide, although there has been a high tendency of relying on stable prices of petroleum and low-production unit price of the nuclear power generation, in recent years, due to a sharp rise in the price of petroleum and a sense of insecurity to the nuclear power generation, many constructions of the thermal power generation that uses coal have been planned.

When the coal has much moisture, the heating value decreases and the transportation costs also increase.

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