Novel double-energy-saving urea yield increase technique through aqueous solution complete cycle

Abstract

The invention provides a novel double-energy-saving urea yield increase technique through aqueous solution complete cycle. Three high pressure apparatuses are added on a high pressure system of the existing device through an original urea synthesizer, namely, a first energy-saving reactor, a stripping tower and a second energy saving reactor. Liquid ammonia, carbon dioxide and a certain proportion of ammonium carbamate solution are conveyed into the first energy-saving reactor to be synthesized, and low pressure steam is generated as a byproduct; a urea mixture from the urea synthesizer is decompressed, the ammonia and the carbon dioxide released from the stripping tower are conveyed into the second energy-saving reactor to synthesize the urea with the ammonium carbamate solution, and low pressure steam is generated as a byproduct; liquid discharged from the bottom part of the stripping tower and liquid discharged from the top of the second energy saving reactor are conveyed into a medium pressure decomposition system. The novel double-energy-saving urea yield increase technique provided by the invention increases the production capacity of the original aqueous solution complete cycle technique device by 50-100% and generates 0.7-0.9Mpa low pressure stream for providing heat sources to heating equipment of successive medium and low pressure systems. The novel double-energy-saving urea yield increase technique provided by the invention is simple in technique procedures, convenient to operate and control, low in urea stream consumption, high in reformation investment yield rate and capable of increasing the operation stability of a high pressure system and a medium pressure system of the aqueous solution complete cycle urea production device and integrally increasing the operation period of the device.

Description

technical field [0001] The invention relates to a process for improving the production capacity of full-circulation urea in aqueous solution and reducing steam consumption, specifically, a new process for energy-saving and production-increasing transformation of the high-pressure system of a full-circulation aqueous urea plant. Background technique [0002] At present, most of the small and medium-sized urea plants in China adopt the full-circulation technology of aqueous solution developed by Stamicarbon in the 1950s. This technology has problems such as high energy consumption, poor controllability of process operation and high probability of process accidents. Traditional aqueous solution full cycle urea production process, synthesis pressure 20MPa, synthesis temperature 188°C, synthesis feed NH 3 / CO 2 3.8~4.2, H 2 0 / CO 2 The ratio is 0.65~0.7, the synthesis tower CO 2 The single-pass conversion rate is 62-66%, the steam consumption per ton of urea is 1.2-1.6 tons, ...

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Problems solved by technology

This technology has problems such as high energy consumption, poor controllability of process operation and high probability of process accidents.

Traditional aqueous solution full cycle urea production process, synthesis pressure 20MPa, synthesis temperature 188°C, synthesis feed NH 3 / CO 2 3.8~4.2, H 2 0 / CO 2 The ratio is 0.65~0.7, the synthesis tower CO 2 The single-pass conversion rate is 62-66%, the steam consumption per ton of urea is 1.2-1.6 tons, and the unit unit urea output is low

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