SU777375A1 - Loose material drying method - Google Patents

Description

(54) METHOD FOR DRYING BULK MATERIAL

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The invention relates to a drying technique and can be used in the chemical and other industries.

Methods are known for drying bulk material by pre-incineration; fuel, mixing the resulting combustion products with secondary air and then feeding the stream of the obtained drying agent into the drying zone 1.

The disadvantage of this method is increased energy consumption due to the need to dilute all combustion products with secondary air to reduce their temperature before entering the drying zone.

The purpose of the invention is to reduce energy consumption.

This is achieved by the fact that part of the fuel in the amount of 10-30% of the required for drying is fed directly to the drying zone at an angle to the flow of the drying agent.

In addition, the direction of flow of fuel supplied directly to the drying zone is periodically changed.

The drawing shows a longitudinal section of a drying unit in which this drying method is implemented.

The installation contains a combustion chamber I with a fuel line 2 and pipelines 3 and 4

for supplying primary and secondary air from blower 5, dryer 6 with fuel line 7, sprayer 8 and chute 9 for loading raw material, 5 receiving bin 10, cyclone 11 for dedusting the drying agent and exhaust fan 12.

The method of drying is as follows.

10 Fuel in the amount of 70-90% of the total amount enters the combustion chamber 1, where it is burned in a mixture with primary air coming from blower 5 via pipeline 3. Combustion products at the exit from the combustion chamber are mixed with secondary air entering through pipeline 4 The obtained drying agent with an air excess factor of 5-8 is supplied to the drying zone of the drying

20 drum 6, where the fuel line 7 through the spray 8 receives the remaining 10-30% of the fuel, burning due to excess air in the drying agent. The latter transfers its heat to the raw material that flows through the chute 9 into the drum 6. The used drying agent is fed through the exhauster 12, the cyclone 11 B atmosphere, and the dried material comes from the drum 6 ъ receiving bin 10.

Depending on the desired mode, the direction of flow of the fuel supplied through the sprayer 8 to the drying zone may periodically change from the opposite direction towards the flow of the drying agent to the associated one.

When burning 10-30% of the fuel in the drying zone, the length of the spray nozzle 8 does not exceed 3 m and the latter almost does not directly affect the material, which is screened like a stream of drying agent from chamber 1. When drying materials that have mostly surface moisture, the fuel in the drying zone is served in an amount corresponding to the lower limit (10%). When drying materials, they have, besides surface moisture, more and chemically bound, fuel is supplied to the drying zone in an amount corresponding to the upper limit (30%). Supply of fuel to the drying zone above 30% can lead to material deterioration and isolation of the drying drum 6.

Thus, burning a part of the fuel directly in the drying zone allows to reduce the flow rate of air entering the furnace, reduce the amount of drying agent, because when burning in the drying zone, oxygen of the drying agent is used, energy consumption for transporting air and the drying agent is reduced, and heat losses are reduced. shih gas treatment. In addition, the supply of a part of the fuel to the drying zone allows to intensify drying due to the use of the radiant component of the flare and the turbulization of the gas flow at the surface of the material being dried.

Claims (2)

1. A method of drying the bulk material by pre-burning the fuel, mixing the resulting combustion products with secondary air and then feeding a stream of the obtained drying agent into the drying zone, characterized in that, in order to reduce energy costs, a part of the fuel in the amount of 10-30% of drying is fed directly into the drying zone at an angle to the flow of the drying agent. 2. Method pop. 1, characterized in that the direction of flow of fuel supplied directly to the drying zone is periodically changed. Sources of information taken into account during the examination 1. M. V. Lykov. Drying in the chemical industry. -M., Khimn, 1973, p. 348, fig. UE-39.