Method for producing ammonium sulfate by removing sulfur through ammonia method

Abstract

The invention discloses a sulfur removal technology belonging to air pollution regulation, and particularly relates to a method for producing ammonium sulfate by removing sulfur through an ammonia method. The method comprises the following steps: introducing ammonia water and tail gas containing sulfur dioxide into a tail gas treatment tower, reacting the sulfur dioxide in the exhaust with the ammonia water to remove sulfur, defogging the gas subjected to sulfur removal, then discharging to obtain a circulating absorption liquid in the tail gas treatment tower, and controlling the pH value of the circulating absorption liquid at 5-6 and the temperature at 40-45 DEG C; concentrating the circulating absorption liquid with tail gas containing sulfur dioxide, which is generated in sulfuric acid production; and when the density is 1.18-1.22 g / cm<3>, partially taking out to prepare solid ammonium sulfate or prepare a 30-40% (mass percentage concentration) ammonium sulfate liquid, and simultaneously recovering the generated sulfur dioxide gas. Thus, the method disclosed by the invention overcomes the problems that ammonium sulfite generated by treating sulfur dioxide through the common ammonia method is low in concentration and high-concentration ammonium sulfite is difficult to oxidize, realizes the low-cost operation of sulfuric acid tail gas treatment, and achieves the purposes of treating one waste with another waste and preparing the waste into a fertilizer.

Description

technical field [0001] The invention relates to a desulfurization technology for air pollution control, in particular to a method for producing ammonium sulfate through ammonia desulfurization. Background technique [0002] Tail gas from industrial sulfuric acid plants is an environmental protection issue of global concern, and its sulfur dioxide must be treated and discharged up to standard. As the country's environmental protection requirements become increasingly strict, on October 1, 2013, the country's new sulfuric acid industry pollutant discharge standard will be officially implemented, and the tail gas sulfur dioxide emission standard stipulated in the new standard is 400mg / Nm 3 , At present, there are many old sulfuric acid production plants that have not yet reached this target. [0003] Among the existing desulfurization technologies, the ammonia flue gas desulfurization method has a higher desulfurization efficiency. Ammonia flue gas desulfurization mainly incl...

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Problems solved by technology

Although ammonium sulfite can also be directly applied as a chemical fertilizer, the stability of the product is poor and it is difficult to be accepted by farmers; if it is used as a raw material for small paper mills, it will produce waste water and cause secondary pollution

If ammonium sulfite is directly oxidized to produce high-quality ammonium sulfate fertilizer, although it is an ideal way to treat sulfuric acid tail gas, the current method of directly introducing air to oxidize ammonium sulfite to produce ammonium sulfate has the following problems: (1) The oxidation efficiency is low: When the concentration is about 10%, the oxidation rate of ammonium sulfite is about 90%, and when the concentration is about 30%, the oxidation rate of ammonium sulfite is only about 60%. (2) A catalyst needs to be added during the oxidation process, and the catalyst is expensive; (3) Oxygen utilization rate is low during oxidation, power consumption is large, and oxidation operation cost is high; (4) Since ammonium sulfite is directly oxidized to ammonium sulfate, only at a lower concentration can there be a higher oxidation rate, resulting in the circulation of the absorption liquid The concentration of ammonium sulfate is also very low. When producing ammonium sulfate, a large amount of external steam is required to forcibly evaporate, concentrate and crystallize, resulting in high energy consumption, severe equipment corrosion, complicated process, high investment, and low level of automatic operation; (5) Sulfurous acid When ammonium is directly oxidized to ammonium sulfate, there is waste water discharge, the desulfurization agent consumes a lot of ammonia water, and a large amount of free ammonia is entrained in the tail gas discharge, which causes a large loss of ammonia and easily causes secondary pollution and other problems.

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