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Method for producing melamine slow cooling crystal production

A melamine, slow cooling technology, applied in sustainable manufacturing/processing, chemical industry, climate sustainability, etc., can solve problems such as energy waste, polluted products, air-conditioning power, etc., and achieve the effect of reducing the pressure of powder purification

Pending Publication Date: 2017-11-03
李鑫
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The following problems exist in the production process: first, the amount of cold air is generally more than 4 times the amount of carrier gas, and the preparation of cold air requires a lot of power; second, a small amount of urea and metal corrosion residues are entrained in the cold air, which enters the crystallizer and contaminates crystallization The third is that the reaction gas cooling and crystallization temperature drop process reduces the heat recovery amount and heat recovery grade of the reaction gas, resulting in energy waste

Method used

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  • Method for producing melamine slow cooling crystal production

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Effect test

Embodiment 1

[0022] Embodiment one: if figure 1 As shown, the melamine crystallizer for cooling by the composite method includes a crystallizer body 1, the top of the crystallizer body 1 is provided with a hot gas inlet 2, the bottom end is provided with a powder outlet 3, and the upper half of the crystal body 1 is provided with a skirt sleeve type The tube heat exchanger 4, the skirt tube heat exchanger 4 includes a communication tube 8 that can pass through the cold medium, and a plurality of longitudinally arranged heat exchange tubes 9 connected to the communication tube 8, and the crystallizer body 1 The lower half is the gas phase quenching and cooling chamber 5, and the ring cooling chamber 5 is provided with 10 air-conditioning inlets 6, and the upper ring quenching and cooling chamber 5 is provided with 10 mixed gas outlets 7 at the upper part of the air-conditioning inlet 6. The cooling medium of the skirt-type tubular heat exchanger can be hot water. The hot reaction gas at 350...

Embodiment 2

[0026] Embodiment two: if figure 1 As shown, the melamine crystallizer for cooling by the composite method includes a crystallizer body 1, the top of the crystallizer body 1 is provided with a hot gas inlet 2, the bottom end is provided with a powder outlet 3, and the upper half of the crystal body 1 is provided with a skirt sleeve type The tube heat exchanger 4, the skirt tube heat exchanger 4 includes a communication tube 8 that can pass through the cold medium, and a plurality of longitudinally arranged heat exchange tubes 9 connected to the communication tube 8, and the crystallizer body 1 The lower half is a gas-phase quenching and cooling chamber 5, and 12 air-conditioning inlets 6 are arranged in the encircling chamber 5, and 12 mixed gas outlets 7 are arranged in the encircling chamber 5 on the upper part of the air-conditioning inlet 6. The cooling medium of the skirt-type tubular heat exchanger is heat-conducting oil, and the hot reaction gas at 350°C enters the crys...

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Abstract

The invention discloses a melamine slow cooling crystallizer which comprises a crystallizer main body. The top of the crystallizer main body is provided with a hot air inlet, and the bottom of the crystallizer main body is provided with a powder outlet. The melamine slow cooling crystallizer is characterized in that the upper half section of the crystallizer main body is provided with a skirt sleeve type pipe exchanger, the lower half section of the crystallizer main body is provided with a gaseous phase quenching cooling chamber, a ring cooling chamber is provided with a plurality of cold air inlets, and the ring cooling chamber on the upper portions of the cold air inlets are provided with a plurality of mixed air outlets. By adoption of the structure, namely by adoption of a two-section cooling method in the crystallizer, energy consumption is reduced, and the heat recovery grade is improved.

Description

technical field [0001] The invention belongs to the technical field of chemical production, and in particular relates to a slow cooling crystallization production method of melamine. Background technique [0002] During the dry production process of melamine, the generated melamine exists in the reaction gas in gaseous form at 350°C, and when the temperature is lowered to below 300°C, the gaseous melamine can be sublimated and become powdery melamine and precipitated. If the conventional heat exchange method is used to cool down, a large amount of precipitated melamine powder will block the heat exchange tubes and heat exchange channels, making the production process unsustainable. [0003] At present, the production of melamine in my country mainly adopts the domestic self-developed gas phase quenching one-step method. The so-called "gas phase quenching" essentially means that in the crystallizer, the high-temperature reaction gas at 350°C is mixed with the low-temperature ...

Claims

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Application Information

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IPC IPC(8): C07D251/62
CPCC07D251/62Y02P20/50Y02P20/10
Inventor 李鑫
Owner 李鑫