Tail gas heat recycling system of iron phosphate production rotary kiln

Abstract

The utility model relates to an iron phosphate production rotary kiln tail gas heat recycling system which is characterized in that an air outlet of a rotary kiln combustion chamber is connected with an air inlet of a kiln tail gas fan through a first air pipe, and an air outlet of the kiln tail gas fan is connected with a hot air side air inlet of an air-air heat exchanger through a second air pipe. A cold air side air outlet of the air-air heat exchanger is connected with an air inlet of the flash evaporation induced draft fan through a fourth air pipe, and an air outlet of the flash evaporation induced draft fan is connected with a combustion chamber air inlet of the flash evaporation drying machine through a fifth air pipe. The heat of the tail gas of the rotary kiln can be effectively recovered through the air-air heat exchanger, so that the temperature of inlet air of the flash combustion furnace is increased in advance, the natural gas consumption of the flash combustion furnace is reduced, and the energy consumption is effectively reduced; and meanwhile, the tail gas temperature of the rotary kiln can be effectively reduced after heat exchange, so that the use of a heat insulation material from a hot side outlet of the air-air heat exchanger to an air pipe of a tail gas system is reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the phosphoric iron production supporting technology equipment field, concretely relates to a kind of phosphoric iron production rotary kiln tail gas heat recycling system. BACKGROUND

[0002] Domestic phosphoric iron process is mainly divided into wet section and dry section, wherein dry section is that the filter cake of dihydrate phosphoric iron after synthesis and aging in wet section is separated from free water by flash drying equipment, further, crystal water in dihydrate phosphoric iron is removed by calcination through rotary kiln, and phosphoric iron after calcination is crushed by grinding machine to obtain phosphoric iron product.

[0003] In dry stage, fresh air is heated by flash drying equipment through natural gas, and then contacts with dihydrate phosphoric iron filter cake to exchange heat, so that water in filter cake is evaporated to separate from free water, and fan matched with flash drying machine transports dried material and air to bag dust collector, and dihydrate phosphoric iron is obtained after separation, and tail gas is discharged through chimney.

[0004] At present, tail gas temperature generated by current process kiln is high, in order to protect air pipe, cold air supplement device is usually installed on tail gas pipeline to reduce tail gas temperature, and most of heat energy is directly discharged with tail gas, which cannot be utilized. SUMMARY

[0005] The utility model discloses a rotary kiln tail gas heat recycling system for phosphoric iron production to solve the problems in the prior art.

[0006] To achieve the above object, the utility model takes the technical scheme that a rotary kiln tail gas heat recycling system for phosphoric iron production, including rotary kiln, characterized by: the air outlet of rotary kiln combustion chamber is connected with the air inlet of kiln tail gas fan through first air pipe, the air outlet of kiln tail gas fan is connected with the hot air side air inlet of air-air heat exchanger through second air pipe, the cold air side air outlet of air-air heat exchanger is connected with the air inlet of flash air fan through fourth air pipe, and the air outlet of flash air fan is connected with the combustion chamber air inlet of flash drying machine through fifth air pipe.

[0007] The hot air side air outlet of air-air heat exchanger is connected with tail gas system through third air pipe.

[0008] The hot side inlet and outlet and cold side inlet and outlet of air-air heat exchanger are respectively provided with temperature sensor to monitor the temperature before and after rotary kiln tail gas heat exchange and the temperature before and after combustion-supporting air heat exchange into flash drying machine.

[0009] The kiln tail gas fan and the flash air fan adopt frequency conversion control, and the frequency is adjusted according to the temperature and the working condition of the flash dryer.

[0010] The kiln tail gas heat recycling system has the advantages that the heat of the kiln tail gas can be effectively recycled through the air-to-air heat exchanger, the temperature of the air into the flash combustion furnace is heated in advance, the natural gas consumption of the flash furnace is saved, and the use of energy consumption is effectively reduced; meanwhile, the temperature of the kiln tail gas can be effectively reduced after heat exchange, so that the use of the heat insulation material on the air-to-air heat exchanger hot side outlet to the tail gas system air pipe is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The utility model discloses a kiln tail gas heat recycling system for phosphoric acid iron production;

[0012] In the figure: 1-rotary kiln, 2-kiln tail gas fan, 3-air-to-air heat exchanger, 4-inducing fan, 5-flash dryer, L1-first air pipe, L2-second air pipe, L3-third air pipe, L4-fourth air pipe, L5-fifth air pipe. DETAILED DESCRIPTION

[0013] Embodiment, see Figure 1 A kiln tail gas heat recycling system for phosphoric acid iron production, comprising a rotary kiln 1, characterized in that: the rotary kiln 1 combustion chamber air outlet is connected with the kiln tail gas fan 2 air inlet through the first air pipe L1, the kiln tail gas fan 2 exhaust outlet is connected with the air-to-air heat exchanger 3 hot air side air inlet through the second air pipe L2, the air-to-air heat exchanger 3 cold air side air outlet is connected with the flash air fan 4 air inlet through the fourth air pipe L4, and the flash air fan 4 air outlet is connected with the flash dryer 5 combustion chamber air inlet through the fifth air pipe L5.

[0014] The air-to-air heat exchanger 3 hot air side air outlet is connected with the tail gas system through the third air pipe L3.

[0015] The air-to-air heat exchanger 3 hot side inlet and outlet and cold side inlet and outlet are respectively provided with temperature sensors for monitoring the temperature before and after the rotary kiln tail gas heat exchange and the temperature before and after the combustion-supporting air heat exchange into the flash dryer.

[0016] The kiln tail gas fan 2 and the flash air fan 4 adopt frequency conversion control, and the frequency is adjusted according to the temperature and the working condition of the flash dryer 5.

[0017] Working process: when the rotary kiln 1 works, start the kiln tail gas fan 2, the combustion tail gas in the combustion chamber of the rotary kiln 1 is sucked into the kiln tail gas fan 2 through the first air pipe L1 and is transported to the hot air side of the air-air heat exchanger 3 through the second air pipe L2, after heat exchange, the tail gas is transported to the tail gas system through the third air pipe L3 for treatment and then discharged. At the same time, cold air is sucked from the cold air side of the air-air heat exchanger 3, after heat exchange, it is transported into the flash air fan 4 through the fourth air pipe L4, and then is transported into the combustion chamber of the flash dryer 5 through the fifth air pipe L5.

[0018] Note: when the flash air fan 4 and the flash dryer 5 are not working, the hot side of the air-air heat exchanger 3 is not controlled to work alone, so as to avoid the heat exchange equipment from being deformed and damaged due to high temperature.

[0019] Temperature sensors are arranged at the inlet and outlet of the hot side and the inlet and outlet of the cold side of the air-air heat exchanger 3, which are used to monitor the temperature before and after the rotary kiln 1 tail gas heat exchange and the temperature before and after the combustion-supporting air of the flash dryer 5 heat exchange.

[0020] The flash air fan 4 is controlled by frequency conversion, and the frequency is adjusted according to the feeding amount of the flash dryer 5. When the feeding amount of the flash dryer 5 increases, the motor frequency of the flash air fan 4 is increased; when the feeding amount of the flash dryer 5 decreases, the motor frequency of the flash air fan 4 is decreased.

[0021] The kiln tail gas fan 2 is controlled by frequency conversion, and when the outlet temperature of the hot side of the air-air heat exchanger 3 is too high, the motor frequency of the kiln tail gas fan 2 is decreased.

Claims

1. A system for recycling heat from exhaust gas of a rotary kiln for producing iron phosphate, comprising a rotary kiln (1), characterized in that: The air outlet of the combustion chamber of the rotary kiln (1) is connected with the air inlet of the kiln tail gas fan (2) through a first air pipe (L1), the air outlet of the kiln tail gas fan (2) is connected with the hot air inlet of the air-air heat exchanger (3) through a second air pipe (L2), the cold air outlet of the air-air heat exchanger (3) is connected with the air inlet of the flash air fan (4) through a fourth air pipe (L4), and the air outlet of the flash air fan (4) is connected with the air inlet of the combustion chamber of the flash dryer (5) through a fifth air pipe (L5).

2. The system for recycling heat from the exhaust gas of a rotary kiln for iron phosphate production according to claim 1, characterized in that: The hot air outlet of the air-air heat exchanger (3) is connected with the tail gas system through a third air pipe (L3).

3. The system for recycling heat from the exhaust gas of a rotary kiln for iron phosphate production according to claim 1, characterized in that: The hot side inlet and outlet and the cold side inlet and outlet of the air-air heat exchanger (3) are respectively provided with temperature sensors.

4. The system for recycling heat from the exhaust gas of a rotary kiln for iron phosphate production according to claim 1, characterized in that: The kiln tail gas fan (2) and the flash air fan (4) are adjusted by frequency conversion control.

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