System and method for preparing crude cyanuric acid continuously by using urea

Abstract

The invention discloses a system and method for preparing crude cyanuric acid continuously by using urea. The system comprises: a differential stirring reactor for receiving urea melt and for deaminating it to produce crude cyanuric acid; a heating device disposed outside a reaction barrel of the differential stirring reactor and used for heating the reaction barrel; an ammonia recycling device connected with a gas outlet of the differential stirring reactor and used for recycling ammonia as a material for urea synthesis. The system and method enable continuous feeding, automated temperature control and automated discharging, rarely cause equipment blockage and blocking, reduce operation intensity of workers and improve work environment, optimize an operation process, and provide an organic integrity of human, machinery, material, process and environment.

Description

technical field [0001] The invention belongs to the field of preparation of chemical raw material intermediates, and in particular relates to a system and method for continuously preparing crude cyanuric acid by using urea. Background technique [0002] Cyanuric acid, also known as cyanuric acid, has the molecular formula C 3 h 3 N 3 o 3 , is white crystal, odorless and slightly bitter taste, it has two tautomers, contains two molecules of crystal water, relative density 1.768 (0°C), loses crystal water when heated to 150°C, and is prone to depolymerization reaction when heated . Further processing can synthesize a variety of fine chemical products, the main derivatives are chlorinated isocyanuric acid, trihydroxyethyl isocyanate and so on. Mainly used in intermediates of chlorinated bleaching agents, resins, antioxidants, paints, coatings, pesticides, selective herbicides and metal cyanide corrosion inhibitors, plastic veneers and wood-based panels, advanced electrical...

AI Technical Summary

Problems solved by technology

[0004] 1) The reaction cycle of the device is long, and the production cycle is as long as 8 hours from feeding, feeding, heating, discharging, cooling, and obtaining crude cyanuric acid;

[0005] 2) The heat loss of the device is large. Because the gas is used to burn the air to heat the urea contained in the material box by radiation, the height of the urea material layer is nearly 200mm, and the heating time is long; the temperature difference is required to be large, and after the hot air is mixed with ammonia, in order to prevent The explosion can only be sent directly out of the boundary to absorb and generate ammonium sulfate for treatment, resulting in a large amount of heat loss; at the same time, the tunnel kiln is bulky, resulting in large heat dissipation and ineffective heat loss;

[0006] 3) Due to intermittent production, the material needs to be manually knocked on the material basin to be discharged, and the material is in the form of a basin-shaped bulk material, and a special crushing process needs to be set up, which increases energy consumption;

[0007] 4) Ammonia is not conducive to recovery, the amount of tail gas is large, and a large amount of process waste air needs to be discharged outside, causing serious environmental pollution; in order to ensure the safety of ammonia, the air volume is increased to ensure that the ammonia concentration is lower than the explosion limit. Large, the tail gas treatment system is particularly large, and the investment is large;

[0008] 5) The device needs to be equipped with a water gas device, which not only increases the investment, but also increases the use of coal and increases the risk of environmental protection and safety;

[0009] 6) The device occupies a large area and requires high investment;

[0010] 7) The material consumption and energy consumption of the device are relatively high: 1.8 tons of urea is required to produce 1 ton of cyanuric acid; the comprehensive energy consumption is 0.300-0.40 tons of standard coal; the number of operators is up to 24

[0011] The traditional process of synthesizing isocyanuric acid by thermal polymerization of urea is to heat urea at 200-330°C under a slight negative pressure to deamination heat polycyclize cyanuric acid. Due to the harsh process conditions, the deamination polymerization reactor industry still uses tunnels Kiln, the thermal energy utilization rate is quite low, the manual workload is large, the safety risks such as ammonia leakage are relatively large, the device occupies a large area, the investment is large, and the environment is poor

[0012] For this reason, many domestic enterprises and scientific research institutes are actively developing continuous production processes, striving to achieve the goals of automatic feeding, automatic temperature control, and automatic discharging. Twin-screw pushers and multi-layer disc reactors have been developed and tested successively. , semi-continuous tunnel kiln and other processes, but because the cyanuric acid material has no melting point, deamination is solidified immediately, causing equipment blockage and locking, and the test cannot be carried out

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