Flue gas waste heat utilization system of mixed alkali dehydration pot

Abstract

The utility model discloses a flue gas waste heat utilization system of a mixed alkali dehydration pot. The flue gas waste heat utilization system comprises a dehydration pot hearth, a flue gas buffer box, a mixed alkali preheater, a chimney, a filter press and a triple-effect evaporator, a flue gas outlet of the dehydration pot hearth is communicated with a gas inlet of the flue gas buffer box, a gas outlet of the flue gas buffer box is communicated with a tube pass inlet of the mixed alkali preheater, and a tube pass outlet of the mixed alkali preheater is communicated with a flue gas inlet of the chimney; a liquid outlet of the filter press is communicated with a shell pass inlet of the mixed alkali preheater, and a shell pass outlet of the mixed alkali preheater is communicated with a liquid inlet of the triple-effect evaporator. The three-effect evaporator has the advantages that the connecting structure is simple and easy to realize, the effective recycling of flue gas waste heat is realized, the concentration time of the three-effect evaporator is shortened, and the steam energy consumption of the three-effect evaporator is saved; meanwhile, the preheated combustion-supporting air enters the hearth of the dehydration pot, so that the limit high temperature of the dehydration pot is effectively improved, the dehydration time is shortened, and the consumption of natural gas energy is reduced.

Description

Technical field:

[0001] The utility model relates to a flue gas waste heat utilization system, in particular to a flue gas waste heat utilization system of a mixed alkali dehydration pot. Background technology:

[0002] The current method for producing indigo is to first mix phenylaminoacetonitrile with mixed alkali recovered from an alkali recovery system and perform a hydrolysis reaction to obtain potassium (sodium) anilinoacetic acid salt, then mix the potassium (sodium) anilinoacetic acid salt with sodium amide in a reactor to react to obtain potassium (sodium) indoxyphenol, which is then sent to an oxidation kettle and blown into air for further oxidation to obtain dioxybisindoxyphenol, and then filtered through a product filter press to obtain an indigo filter cake. The alkali concentration of the filtrate obtained by the filtration is 14-15%, which is sent to an alkali recovery system for recovery, that is, first concentrated into a solution with a concentration of 45% by a triple-effect evaporator, then cooled by a cooler, and then filtered by a first filter press. After passing through the decolorization device and the first evaporation and concentration device, the liquid is sent to the oxidation kettle and CO2 is introduced for reaction. It is then filtered through the second filter press to obtain soda ash packaging. The filtrate from the filtration is concentrated to a concentration of 70% by the second evaporation and concentration device. Finally, it is heated and dehydrated in a dehydration pot to obtain a mixed alkali with a concentration of 92% for participating in the hydrolysis reaction. The dehydration pot uses fuel gas combustion for heating and dehydration. The high-temperature flue gas of 400-500℃ generated by the combustion and heating is directly connected to the chimney for discharge. During the discharge process, the temperature of the flue and chimney is too high (even burning the chimney made of carbon steel red), posing a safety hazard of burns and resulting in huge heat loss. Utility model content:

[0003] The purpose of the utility model is to provide a flue gas waste heat utilization system for a mixed alkali dehydration boiler which has a simple connection structure and realizes effective recovery and utilization of flue gas waste heat.

[0004] The utility model is implemented by the following technical scheme: The purpose of this patent is to provide a flue gas waste heat utilization system of a mixed alkali dehydration pot, which includes a dehydration boiler chamber, a flue gas buffer box, a mixed alkali preheater, a chimney, a filter press and a triple-effect evaporator; the flue gas outlet of the dehydration boiler chamber is connected to the air inlet of the flue gas buffer box, the air outlet of the flue gas buffer box is connected to the tube side inlet of the mixed alkali preheater, and the tube side outlet of the mixed alkali preheater is connected to the smoke inlet of the chimney; the liquid outlet of the filter press is connected to the shell side inlet of the mixed alkali preheater, and the shell side outlet of the mixed alkali preheater is connected to the liquid inlet of the triple-effect evaporator.

[0005] Furthermore, it also includes an air preheater, an induced draft fan and a blower. The tube-side outlet of the mixed alkali preheater is connected to the tube-side inlet of the air preheater, the tube-side outlet of the air preheater is connected to the smoke inlet of the induced draft fan, and the smoke outlet of the induced draft fan is connected to the smoke inlet of the chimney; the air outlet of the blower is connected to the shell-side inlet of the air preheater, and the shell-side outlet of the air preheater is connected to the combustion-supporting air inlet of the dehydration boiler chamber.

[0006] The advantages of the present invention are as follows: 1. The connection structure of the present invention is simple and easy to implement. By setting up a mixed alkali preheater, high-temperature flue gas is used to preheat alkaline water with a concentration of 15%, so that it is successfully dehydrated to a concentration of 27%, thereby realizing effective recovery and utilization of flue gas waste heat, shortening the concentration time of the triple-effect evaporator, and saving the steam energy consumption of the triple-effect evaporator; 2. By setting up an air preheater, the residual heat of the flue gas is used to preheat the combustion-supporting air entering the dehydration boiler chamber, thereby realizing effective recovery and utilization of flue gas waste heat. At the same time, the preheated combustion-supporting air enters the dehydration boiler chamber, effectively increasing the maximum high temperature of the dehydration pot, shortening the dehydration time, and saving the consumption of natural gas energy. Description of the drawings:

[0007] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0008] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0009] Dehydration boiler chamber 1, flue gas buffer box 2, mixed alkali preheater 3, chimney 4, filter press 5, triple-effect evaporator 6, air preheater 7, induced draft fan 8, blower 9. Specific implementation method:

[0010] Example: Figure 1As shown, a flue gas waste heat utilization system of a mixed alkali dehydration boiler comprises a dehydration boiler chamber 1, a flue gas buffer box 2, a mixed alkali preheater 3, a chimney 4, a filter press 5, a three-effect evaporator 6, an air preheater 7, an induced draft fan 8 and a blower 9; the flue gas outlet of the dehydration boiler chamber 1 is connected to the air inlet of the flue gas buffer box 2, the air outlet of the flue gas buffer box 2 is connected to the pipe side inlet of the mixed alkali preheater 3, and the pipe side outlet of the mixed alkali preheater 3 is connected to the air side outlet of the air preheater 7. The tube-side inlet is connected, the tube-side outlet of the air preheater 7 is connected with the smoke inlet of the induced draft fan 8, and the smoke outlet of the induced draft fan 8 is connected with the smoke inlet of the chimney 4; the liquid outlet of the filter press 5 is connected with the shell-side inlet of the mixed alkali preheater 3, and the shell-side outlet of the mixed alkali preheater 3 is connected with the liquid inlet of the triple-effect evaporator 6; the air outlet of the blower 9 is connected with the shell-side inlet of the air preheater 7, and the shell-side outlet of the air preheater 7 is connected with the combustion-supporting air inlet of the dehydration boiler chamber 1.

[0011] Working principle: The high-temperature flue gas of 400-500℃ after combustion first enters the flue gas buffer box 2 through the refractory flue, and then enters the pipe process of the mixed alkali preheater 3 to dehydrate the 15% alkaline water from the filter press 5 to the alkaline water with a concentration of 27%, and then transported to the triple-effect evaporator 6 to be concentrated into a solution with a concentration of 45%, thereby realizing the effective recovery and utilization of the waste heat of the flue gas, and at the same time shortening the concentration time of the triple-effect evaporator 6 by 2 hours, and saving the steam energy consumption of the triple-effect evaporator 6. After being preheated by the mixed alkali, the high-temperature flue gas is cooled to approximately 200°C before entering the air preheater 7 to preheat the natural gas furnace combustion air before being sent to the dehydration boiler chamber 1 for combustion. Preheating the combustion air to 100°C before entering the dehydration boiler chamber 1 avoids the reverse cooling effect, raising the furnace's maximum temperature from 800°C to 1000°C. This effectively recycles the flue gas waste heat. Simultaneously, the preheated combustion air entering the dehydration boiler chamber 1 effectively raises the maximum temperature of the dehydration pot, shortening dehydration time and saving natural gas energy consumption. After passing through the air preheater 7, the high-temperature flue gas is transported by the induced draft fan 8 to the chimney 4 for low-temperature discharge.

[0012] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flue gas waste heat utilization system for a mixed alkali dehydration boiler, characterized in that: It includes a dehydration boiler chamber, a flue gas buffer box, a mixed alkali preheater, a chimney, a filter press and a triple-effect evaporator; The flue gas outlet of the dehydration boiler chamber is communicated with the air inlet of the flue gas buffer box, the air outlet of the flue gas buffer box is communicated with the tube side inlet of the mixed alkali preheater, the tube side outlet of the mixed alkali preheater is communicated with the smoke inlet of the chimney; the liquid outlet of the filter press is communicated with the shell side inlet of the mixed alkali preheater, and the shell side outlet of the mixed alkali preheater is communicated with the liquid inlet of the triple-effect evaporator.

2. The flue gas waste heat utilization system of the mixed alkali dehydration boiler according to claim 1 is characterized in that: It also includes an air preheater, an induced draft fan and a blower. The tube-side outlet of the mixed alkali preheater is connected to the tube-side inlet of the air preheater, the tube-side outlet of the air preheater is connected to the smoke inlet of the induced draft fan, and the smoke outlet of the induced draft fan is connected to the smoke inlet of the chimney; the air outlet of the blower is connected to the shell-side inlet of the air preheater, and the shell-side outlet of the air preheater is connected to the combustion-supporting air inlet of the dehydration boiler chamber.

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