Dilute nitric acid device adopting double pressure method

Abstract

The invention relates to a dilute nitric acid device adopting a double pressure method, and the device can increase output at the high temperature season and improve heat energy recovery efficiency. The device is characterized in that a gaseous ammonia outlet of an ammonia evaporator is communicated with a cold fluid inlet of a second ammonia superheater; a cold fluid outlet of the second ammonia superheater is communicated with a cold fluid inlet of a first ammonia superheater; the gaseous ammonia outlet of the ammonia evaporator is communicated with the cold fluid inlet of the first ammonia superheater; a gaseous ammonia inlet of an ammonia filter is communicated with a cold fluid outlet of the first ammonia superheater; a tail gas outlet of a tail gas expansion machine is communicated with a thermal fluid inlet of the second ammonia superheater; an air filter, an air blast dehumidification device and an axial flow compressor are sequentially connected; a gas outlet of the air filter is communicated with a gas inlet of an air blower; a gas outlet of the air blower is communicated with a thermal fluid inlet of a heat exchanger; a thermal fluid outlet of the heat exchanger is communicated with an inlet of a demister; an outlet of the demister is communicated with an inlet of the axial flow compressor; a cold fluid outlet of the heat exchanger, a cold water pump, a refrigerating unit and a cold fluid inlet of the heat exchanger are sequentially communicated.

Description

technical field [0001] The invention relates to a double pressurized dilute nitric acid device. Background technique [0002] The double-pressurization nitric acid plant adopts the double-pressurization method to produce nitric acid, such as the Chinese patent with the application number 201420293262.7 and the name of the double-pressurization nitric acid production device. [0003] There are following disadvantages in the present double pressurized nitric acid plant: [0004] 1. In the high temperature season, the output cannot reach the design average value. The main reason is that the air pumping volume of the air axial flow compressor in the "four-in-one unit" is too small, which restricts the output of finished nitric acid products of the production device. [0005] 2. Due to the design of the exhaust gas turbine in the double-pressurized dilute nitric acid device, the temperature of the outlet NOx exhaust gas is generally higher than the design value of 105°C, and in ...

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Problems solved by technology

[0004] 1. In the high temperature season, the output cannot reach the design average value. The main reason is that the air pumping volume of the air axial flow compressor in the "four-in-one unit" is too small, which restricts the output of nitric acid finished products of the production device.

[0005] 2. Due to the design of the tail gas turbine in the double-pressurized dilute nitric acid device, the temperature of the outlet NOx tail gas is generally higher than the design value of 105°C, and in some devices it is as high as 170°C or more. The high-temperature tail gas is sent directly to Ф1. 2×62m exhaust chimneys are discharged at high altitude, and the low-temperature heat energy of the exhaust gas cannot be fully recovered and utilized

The main reasons for the high exhaust gas temperature are 1. The exhaust gas temperature at the waste heat boiler outlet in the device is 480°C higher, resulting in a 370-380°C higher tail gas temperature at the tail gas inlet; 2. At the same time, the actual heat recovery efficiency of the exhaust gas turbine is also low. There is a certain gap with the design value, so the temperature of the exhaust gas at the outlet is high

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