Method for recovering acid making waste heat

Abstract

The invention discloses a method for recovering acid making waste heat of sulfur acid making or smelting acid making. The method comprises the following steps of: recovering partial heat carried by SO3 gas discharged from a first-section outlet, a second-section outlet and a third-section outlet of a converter in the production process of making acid; recovering heat generated by high temperature of a dry absorption system; and transferring partial heat carried by acid of a dry absorption heat recovering system to boiler water feed by using a heat exchanger on a boil water feed channel of an outlet of a reacting furnace. The scheme uses heat absorbed by dry absorption high temperature to preheat the boiler water feed of an outlet of a sulfur burner and converts the partial heat into medium pressure overheat steam. Therefore, the method can save investment, reduces requirements for soft water quality, and improves generating efficiency above all. The method appropriately modifies a heat recovering system of a converting system at the same time. The method saves a coal economizer, increases a superheater and is additionally provided with an air preheater. For smelting fume acid making, the method can provide a high temperature absorption system on the dry absorption part, and the generated heat can preheat the boiler water feed in the smelting part.

Description

technical field [0001] The invention relates to a method for recovering waste heat from industrial acid production, in particular to a method for recovering waste heat from sulfuric acid production or smelting acid production. Background technique [0002] Modern sulfuric acid plants, especially sulfuric acid production, are not only used as a plant for the production of sulfuric acid, but also as an energy plant. It uses sulfur incinerator S+O 2 → SO 2 A waste heat boiler is installed behind the sulfur incinerator to produce medium-pressure steam of 4.0-6.0Mpa; using the waste heat in the conversion process, the steam is heated to superheated steam at 450°C, that is, a low-temperature superheater is added at the outlet of the fourth stage, and the A high-temperature superheater is added to the outlet of the first stage, so that the saturated steam from the boiler is heated to superheated steam at 450°C; at the same time, the low-temperature waste heat is used to preheat t...

AI Technical Summary

Problems solved by technology

However, from the perspective of the second law of thermodynamics, that is, it is defective from the perspective of usable energy utilization, because the dry suction produces low-pressure steam, and its thermal efficiency of power generation is less than 20%; 30% or more

The second is to set up two boilers, which not only increases the investment, but also increases the burden on production management.

Third, because the pipes of the dry-suction boiler are made of special stainless steel, stainless steel is afraid of chloride ions, and the water quality requires chloride ions to be less than 0.5PPM, which increases the cost of water treatment

But so far the waste heat from smelting flue gas conversion and dry absorption has basically not been utilized, and its utilization method is similar to that of pyrite acid production.

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