Method for economically recycling sulphur dioxide from low-concentration or non-continuity flue gas to produce sulphuric acid

Abstract

The invention discloses a method for preparing sulphuric acid by economically recovering sulfur dioxide in low-concentration or noncontinuous flue gas, which comprises that: the flue gas containing the sulfur dioxide is subjected to purification, dust and impurity removal, temperature reduction, and acid mist removal, and then divided into two paths; one path of the flue gas is sent to a desulfurization working section, high-purity SO2 gas generated after absorption and desorption of the flue gas is evenly mixed into the other path of flue gas which is not subjected to desulfurization, the SO2 concentration of the mixed flue gas is improved to be more than 5 percent, and the mixed flue gas enters a single-conversion single-absorption acid preparation working section; and tail gas after acid preparation enters the desulfurization working section again for desulfurization, and is discharged after the SO2 content is far lower than the discharge standard. The process changes smelter off-gas which cannot meet the requirement of preparing acid by a contact method originally into the flue gas which can prepare the acid normally, and does not need desulfurizing all the flue gas, so the method greatly reduces energy consumption, running cost and investment, and the discharge amount of SO2 is far lower than that of a conventional flow so as to solve a difficult environmental protection problem for partial non-ferrous metallurgical plants and accord with the policy of national energy saving, energy consumption and pollution reduction.

Description

technical field [0001] The present invention relates to sulfuric acid produced by contact method and absorption-desorption method desulfurization process, especially SO 2 Then the process of making sulfuric acid. Background technique [0002] At present, the industrial production of sulfuric acid basically adopts the contact method of acid production process. Regardless of the "one-turn-one-suction" or "two-turn-two-suction" process, the SO 2 The concentration has certain requirements. Generally speaking, when the SO in the flue gas 2 When the concentration is higher than 5%, the self-heating balance of the "two conversion and two suction" process can be realized, and the tail gas can be directly discharged up to the standard; when the SO in the flue gas 2 When the concentration is between 3% and 5%, the self-heating balance of the "one-turn-one-suction" process can be achieved, but the exhaust gas needs to be added to meet the standard, and the more stable the concentrati...

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Problems solved by technology

[0003] However, the general absorption-desorption desulfurization process is a process with high energy consumption and high operating cost, which requires a large amount of steam

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