Mixed-flow discharge gas treatment method and treatment method

Abstract

The invention discloses a new mixed-flow discharge gas treatment device and a method. The discharge gas enters the device from the top of the device so as to realize the integrated function of absorption of acidic gas in the discharge gas by ammonia-containing alkaline absorption liquid, oxidisation and crystallisation. The technical proposal of the invention aims to provide a discharge gas distributor and an absorption liquid spray thrower with a spraying nozzle mounted upwards such that five different gas-liquid contact areas, including a gas uniform flow area, a gas mixed flow area, a gas forward flow area, a gas-liquid separation area and an absorption liquid storage tank, are arranged in the discharge gas treatment device. The beneficial effects of the invention are that the treatment efficiency is 98-99%, the pollutant content in the purified discharge gas is 50-250mg / Nm3, the ammonia escape control effect is excellent, the escaped ammonia content in the purified discharge gas is 5-25mg / Nm2, the treatment device has a simple structure, optimises the water utilisation, and has obvious application prospect in the field of discharge gas purification.

Description

technical field [0001] The invention relates to a device and method for treating exhaust gas, that is, flue gas, especially a desulfurization device and method for recovering sulfur oxides in flue gas with ammonia as raw material to produce useful products with high added value, belonging to electric power, metallurgy, environmental protection and chemical industry technology field. Background technique [0002] Thermal power plants that use coal or oil as fuel, and sintering machines in iron and steel plants emit a large amount of flue gas, referred to as exhaust or flue gas. This type of flue gas contains SO 2 , SO 3 , NO 2 , NO, HCl and HF and other acidic gaseous harmful substances, especially SO 2 It is the main substance that forms acid rain. One way to solve acid rain pollution is flue gas purification, especially flue gas desulfurization (FGD, Flue Gas Desulfurization) using alkaline substances as raw materials, or flue gas scrubbing (Scrubbing). [0003] Accord...

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Problems solved by technology

However, in practice, the absorption liquid circulation volume of this scheme is very large, and the gas-liquid ratio, that is, the standard flow rate of flue gas treatment / total flow rate of circulating absorption liquid, is too small, generally less than 60, and even exceeds the ratio of limestone as raw material. The circulation volume of the calcium method desulfurization technology leads to excessive energy consumption and investment. Moreover, due to the excessive circulation volume, the crystallization of ammonium sulfate is too fine, and subsequent separation becomes difficult. The competitive advantage with the calcium method is obviously weakened

[0007] Chinese patent CN1178735C (2002) also discloses an ammonia desulfurization method and device using a countercurrent tower. In particular, the desulfurization tower is divided into an oxidation section, a concentration section, an absorption section, a water washing section and a demister section, but the circulation volume of the absorption liquid is too small , that is, the gas-liquid ratio is too high, which is 2000-5000, and the problem of ammonia escape has not been solved.

Moreover, in practical applications, the structure of this type of desulfurization tower is too complicated and the equipment is easy to block

Chinese patents CN2790569Y and CN1648049A (2005) proposed a desulfurization tower with an ammonia recovery section to try to solve the problem of ammonia loss, and the gas-liquid ratio was reduced to 200-2000. The structure is too complex and has the disadvantage of easy blockage of equipment, so it is difficult to further popularize and apply

In fact, since the water in the flue gas desulfurization process is very precious, it is difficult to use water

In addition, the ammonium sulfate slurry outlet of this desulfurization tower is above the air inlet, which may cause the circulation pump to be inefficient and even difficult to operate due to the possibility of air entering the circulation pump

Therefore, the application of this desulfurization tower configuration is also limited, which also limits the popularization and application of ammonia desulfurization technology

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