Demchuk I. Conversion of N-containing compounds of flash steam condensate of carbamide production into hydrazine sulfate

In during dehydration of the synthesis-solution of carbamide. Flash steam the dissertation research the actual scientific and practical task of working out of the recovery technology of waste utilization by the conversion of N-containing compounds of condensate of flash steam of carbamide production into hydrazine sulphate is solved. The major part of wastewaters from carbamide production appears in the node of flash steam condensation condensates contain aqueous solutions of ammonium and N amide with a mass concentration of ammonia up to 5 % and carbamide up to 3%, as well as dissolved carbon dioxide, in their composition. The solution to this problem has a positive technological and environmental aspect, and also covers conceptually new approaches to energy sources that tend to end. The current trends in N-containing wastewater treatment technologies are analyzed. Water purification from compounds of Nitrogen (N), such as chlorination, ozonation, ultraviolet irradiation treatment, purification using ion exchange materials, electrolysis, ammonia airflow, requires a use of expensive reagents and special equipment, it is rather energy-intensive. These methods are ineffective in the case of purification of contaminated water from compounds, which contain amide and nitrate N. Formation of 1.5 m3 of wastewater per 1 ton of carbamide in the form of flash steam condensate accompanies carbamide production. The major part of wastewater with the mass concentration of carbamide of not more than 300 mg/dm3 and the mass concentration of ammonia of not more than 100 mg/dm3 is goes to purification after hydrolysis and desorption at biological treatment plants . It is necessary to purify flash steam condensate from nitrogen compounds by two-stage desorption and hydrolysis. Disposal of residual N-containing compounds occurs at biological wastewater treatment plants under industrial conditions. The efficiency of purification of wastewater, which contains bounded N, is about 77 % on average at plants for nitric-denitrification. The current trends in the technology of the synthesis of hydrazine and hydrazine sulfate are analyzed. A recovery technology has been developed for the disposal of effluents containing compounds of amide and ammonium Nitrogen, by the method of converting bound N into intermediate product − N2H4 and its subsequent removal as a low-soluble salt − N2H4∙H2SO4. The study proposes a new method for the disposal of N-containing compounds in flash steam condensate of carbamide production by processing ammonia, carbamide and biuret to hydrazine sulfate. The study on the synthesis of hydrazine sulfate in wastewater of carbamide production has defined mechanisms occurring during the synthesis of raw hydrazine in electromagnetic reactor. The study has proved that the proposed method of disposal is economically viable, environmentally friendly and energy efficient. It reduces a load on biological wastewater treatment plants, reduces the cost of electrical and thermal energy. The method gives a possibility to process N-containing compounds of flash steam condensate into an expensive product ‒ hydrazine sulfate. Experimental studies have confirmed that electromagnetic radiation has a positive effect on the synthesis of raw hydrazine. This leads to an increase in efficiency of the hydrazine synthesis reactor by 88 %. We have analyzed three of the most probable chemistries of the process of raw hydrazine synthesis reactions using the non-imperial method of quantum chemistry. The study has shown that the initial yield of the finished product is 5.3 kg per 1 m3 of nitrogen-containing raw materials during disposal of flash steam condensate at a model plant by processing into hydrazine sulfate taking into account an optimization parameter. There is an increase in the yield of the final product to 6 kg per 1 m3 at repeated multiple use of the filtrate as a source of sulfuric acid. We have performed a projection of the results of the model installation at industrial scale taking into account an operation of the carbamide synthesis device, with a capacity of 330,000 tons per year. Thus, we have identified that the maximum estimated production capacity of the hydrazine sulfate synthesis unit is 132÷150 kg per day. We have calculated the profitability of the device for the synthesis of hydrazine sulfate considering the obtained data on the estimated capacity of the device. It is established that the net profit is at least 12 % according to the proposed scheme in the production of hydrazine sulfate. It is confirmed that the introduction of wastewater disposal technology will reduce the cost of urea by 2.37 %, which is about $ 1.6 billion in cash equivalent per year.