Energy-saving type urea hydrolysis system steam temperature and pressure reduction device

Abstract

The invention provides an energy-saving type urea hydrolysis system steam temperature and pressure reduction device which can realize heat circulation of a urea hydrolysis system, recover high-temperature and high-pressure steam heat for secondary utilization, form an energy-saving type circulation loop, simplify arrangement of system equipment, improve operation economy, reduce transformation cost and improve temperature and pressure reduction quality. The device comprises a heat exchanger which is provided with a steam inlet, a steam outlet, a dilution air inlet and a dilution air outlet. The steam inlet is connected with a gas source for providing high-temperature steam through a high-temperature steam pipeline, and a pressure regulating valve is arranged on the high-temperature steam pipeline. The dilution air inlet is connected with an air source for providing cold dilution air through a cold dilution air pipeline, a flow regulating valve and a flow meter are arranged on the cold dilution air pipeline, and the steam temperature and pressure reduction device is arranged between a urea hydrolysis reactor and a flue gas heat exchanger.

Description

technical field [0001] The invention belongs to the technical field of urea hydrolysis system, and in particular relates to an energy-saving steam temperature reduction and pressure reduction device for urea hydrolysis system. Background technique [0002] Urea hydrolysis to ammonia is a mature denitrification reducing agent preparation process. Many thermal power units at home and abroad have completed the transformation of urea hydrolysis instead of liquid ammonia. [0003] The principle of urea hydrolysis reaction is to inject a urea solution with a mass concentration of about 50% into the hydrolysis reactor and heat it to a certain temperature and pressure to undergo a hydrolysis reaction to generate NH 3 , CO 2 and water vapor, then enter the ammonia-air mixer in the denitrification zone, mix with hot dilution air, and then send it to the denitration reactor. The hot dilution air is generally obtained by heating the cold dilution air with a flue gas heat exchanger arra...

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Problems solved by technology

Therefore, the above-mentioned steam desuperheating and decompression process consumes a lot of energy, and additional desuperheating devices need to be installed to cool the steam, and a large amount of desuperheating water will be wasted during cooling, which increases the complexity of the system and increases the overall operating cost, not only In this way, it is also necessary to equip corresponding waste water treatment devices for secondary treatment of the desuperheating water, and the cooling efficiency and effect are not satisfactory, which affects the economical operation of the unit

[0005] In addition, as mentioned above, after the urea hydrolysis reaction, the products generated after urea hydrolysis need to be mixed with hot dilution air for denitrification in the denitrification zone. After heating to obtain thermal dilution air, mix it with the product. When the amount of thermal dilution air used is large, it is necessary to set up a flue gas heat exchanger with a large heat exchange area for heating to obtain the required thermal dilution air. Excessively large heat exchangers It is more difficult to consider how to arrange, which increases the difficulty of the layout of the urea hydrolysis system

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