Method and device for removing nitrogen oxide in waste gas of marine diesel engine by use of sodium chlorite seawater solution

Abstract

The invention discloses a method for removing nitrogen oxide in waste gas of a marine diesel engine by use of a sodium chlorite seawater solution. The method comprises steps as follows: 1, desulfuration and dust removal treatment; 2, denitration treatment; 3, waste liquid treatment: a waste liquid obtained after desulfuration and dust removal treatment is subjected to solid-liquid separation treatment, the obtained waste liquid and the waste liquid obtained after the denitration treatment are mixed for a reaction, the pH value of the mixed liquid is larger than 6.5, and the mixed liquid is discharged into the sea when the content of NO3<2-> meets the discharge requirements. The invention further discloses a device for removing nitrogen oxide in the waste gas of the marine diesel engine by use of the sodium chlorite seawater solution. The device comprises a sodium chlorite solution water tank, a denitration spraying tower, a desulfuration spraying tower, a separation device, a mixed water tank and a seawater inlet pipe. The denitration effect achieved by use of the sodium chlorite seawater solution is better and can meet the related discharge requirements, the waste liquid after the denitration treatment doesn't pollute the seawater, the equipment cost and the chemical cost are reduced, besides, flexible arrangement of equipment is facilitated, and the operation is convenient.

Description

technical field [0001] The invention relates to the fields of air pollution control and ship tail gas emission control, in particular to a method and a device for removing nitrogen oxides in ship diesel engine exhaust gas by using sodium chlorite seawater solution. Background technique [0002] With the development of international trade, the economy of ship transportation has become more and more obvious, resulting in more and more goods being transported by ship. However, many ships use low-quality fuel oil as fuel, and the pollution of marine diesel engine exhaust to the environment is becoming more and more serious. According to the data provided by Norway to the International Maritime Organization, the total amount of particle pollutants emitted by ships at sea every year is equivalent to half of the particle pollutants emitted by global automobiles, and the total amount of nitrogen oxides emitted by ships accounts for the total amount of nitrogen oxides emitted globall...

AI Technical Summary

Problems solved by technology

The method of using oxidants and absorbents separately will increase the initial investment cost of the equipment, the cost of medicines will also increase, and the economy will be reduced, and the use of two sets of reaction devices will increase the equipment footprint, which is not conducive to flexible layout

In the patent "A device and method for desulfurizing and dust-removing ship exhaust by using seawater" (Patent No. CN102274682A), the desulfurized solution is mixed with seawater and discharged into the sea directly, and the pH value of the solution is difficult to meet the discharge requirement of greater than 6.5

At the same time, the solution after desulfurization contains a large amount of SO 3 2- , directly discharged into seawater will be decomposed into SO again 2 , causing secondary pollution

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