Method and device for utilizing heat energy of flue gas produced by calcining in rotary kiln in process of producing titanium dioxide by sulfuric acid method

Abstract

The invention relates to a method for utilizing heat energy of flue gas produced by calcining in a rotary kiln in the process of producing titanium dioxide by a sulfuric acid method, which comprises the following three aspects of: (1) performing electric precipitation to purify high-temperature flue gas produced in a rotary calcining kiln, collecting dust by a dry method, and returning a recycled product to the rotary kiln for calcining again; (2) spraying 20 percent waste acid produced in the production process to one part of the purified high-temperature flue gas, performing mass transfer and heat transfer, evaporating moisture in the waste acid to improve the concentration of the waste acid to 30 percent, purifying 70 to 80 DEG C low-temperature tail gas produced by concentrating the waste acid by using an electric demisting system, and discharging the tail gas when the tail gas reaches the standard; and (3) returning the other part of the purified high-temperature flue gas to the rotary calcining kiln for recycling, supplementing heat, and adjusting temperature gradient in the kiln. Materials in the flue gas are recycled by the dry method, and the yield of a product is improved by about 0.6 percent; and a large amount of flue gas waste heat is comprehensively utilized, and the effects of saving energy and reducing emission are obvious. Meanwhile, the invention discloses a set of device for utilizing the heat energy of the flue gas produced by calcining in the rotary kiln, which is designed according to the method.

Description

technical field [0001] The invention relates to a method for utilizing waste heat of flue gas in the calcining process of a rotary kiln in the production of titanium dioxide by sulfuric acid method, and also relates to a set of heat energy utilization devices for calcining flue gas of a rotary kiln designed by adopting the method. Background technique [0002] The production process of sulfuric acid titanium dioxide is long, there are many production processes, and the energy consumption of the product is high, especially the semi-finished product (metatitanic acid or hydrated titanium dioxide) emits a large amount of high-temperature flue gas during the calcination process. Every ton of titanium dioxide produced emits 20,000-25,000 M 3 Flue gas, the temperature of the flue gas is as high as 380-420 ° C, and the heat is large. The flue gas also contains a certain concentration (220-300mg / M 3 ) of titanium dioxide has considerable recovery value. Rotary kiln equipment is u...

AI Technical Summary

Problems solved by technology

If the high-temperature flue gas is not purified, the titanium dioxide contained in it will cause overburning when it enters the rotary kiln, which will affect the product quality

[0004] The existing method does not reuse the heat energy of the flue gas in the rotary kiln equipment, and at the same time does not purify the high-temperature flue gas before recycling the product, which does not conform to the national energy-saving and emission-reduction policy, and there is a large waste of resources and energy

Images