SU766618A1 - Method for cleaning gases from mercaptanes - Google Patents

Description

The invention relates to techniques for cleaning exhaust gases during the firing of cement clinker.

A known method of purification of exhaust gases with a wet method for the production of cement clinker, which consists in injecting sludge into pipelines and then into cyclone separators in which dust is trapped in sludge HJ.jq

The disadvantages of this method are the incomplete collection of dust, the inability to remove alkali from the sludge, which limits the choice of raw materials for cement production, the danger of clogging ^{with the} equipment during prolonged use and during short stops, since the dust has some astringent property.

The closest in technical essence 20 and achieved result ^v is a method of cleaning dust from cement production gases, including humidification of gases with water, followed by cleaning in electrostatic precipitators (2). ¹ 25

The disadvantage of this method is the low degree of purification and the inability to use the captured dust in the production of cement due to the formation of setting sediment. thirty

The aim of the invention is to increase. increasing the degree of purification and the possibility of using captured dust in cement production.

This goal is achieved by the fact that in the proposed method, the gases after treatment in electrostatic precipitators are treated with solutions of sodium carbonate or potassium carbonate, or their mixture at a concentration of R ₂ 0 _o61u equal to 30 - 100 g / l, followed by filtration upon reaching W: T = 7: 1 - 10: 1 and washing the obtained precipitate at W: T = 2: 1 - 5: 1.

The optimality of the selected solution concentrations and the ratio W: T is determined by the following.

When using solutions of soda and potash with a concentration of less than 30 g / l according to R ₂ O'consolidation of the precipitate occurs, as a result of which the hydrodynamics of the dust collection process are disturbed and the goal is not achieved.

Using a concentration of more than 100 g / l is uneconomical.

When the alkali concentration is in the range of 30 - 100 g / l according to R ₂ 0, a single wash at W: T = 2: 1 - 5: 1 ensures the condition of the obtained precipitate according to the R ₂ 0 content, and the wash water can be fully used in the cycle.

When the ratio of W: T below 7: 1, due to an increase in the viscosity of the medium, the pressure of the circulation pump increases sharply. At W: T higher than 10: 1, an excess of ³ liquid is in circulation, which reduces the efficiency of the method.

Example 1. The capture of cement dust is carried out in a hollow scrubber on a drying unit consisting of a furnace, a drying drum (14 + 22), cyclones, a hollow scrubber, blowing and traction fans. A pressure tank 15 is fitted under the scrubber, equipped with a centrifugal pump, which, under a pressure of 5-7 atm, circulates the liquid in the scrubber through two inner rings with holes of 2 mm, in steps of 20 and 40 mm. In this way a two-tier film curtain is created through which dusty gases are passed. The flue gas temperature of 150 ° C and the C0 ₂ content therein ^ 3%. The gases entering the scrubber with a special device are dusted with fractions <40 mm and particle size distribution:

particle size, microns 30-20 20-15 15-10 10-5 <5 ³⁰ number of particles,% 11.55 19.36 18.75 17.14 33.2

The concentration of cement baked dust is. 0.5 g / nm ^? . Trapping is carried out with water and solutions of soda 35 and potash. · The amount of dusty gases entering the “Cleaning” is 10,000 nm}. H. The solutions are circulated until pulp is obtained with a ratio of W: T = 8: 1, while part of the pulp 40 is taken for filtration, the liquid part of which goes back to the scrubber. The losses of the liquid phase are compensated by washing water. The resultant filtrate to precipitate at proglyvke L: S = 3: 1 with a content of 0,73% R ^ O can zova.t ⁴⁵ The use for the manufacture of cement slurry. The results show that with an irrigation density of 0.5 l / nm *, hydraulic resistance of 15 mm H ₂ 0 and the use of solutions of soda and potash, complete dust collection is achieved to obtain an uncoated sediment suitable for returning to the stage of preparation of cement slurry.

Upon reaching W: T = 8: 1, pulp is circulated every 2 to 3 hours for 30 minutes for 3 days, after which filtration is carried out. The pulp in circulation does not seize.

Example 2. From the dust captured by electrostatic precipitators, with the content of CaOovsc ^- 50.7%; CaO _St. -. 8.12%; CaO _AAKZ 1.34%; SiOjoBui, - 16.4%; insoluble, precipitate 7.38%; R ₂ O ₅ 6.64%; Fe ₂ O ^ 2.44%, PPP - 23.6% and the particle size distribution specified in Example 1, two types of dough are prepared: with water and solutions of soda and potash. Cylinders with dimensions d = 30 mm are prepared from dough; h = 40 mm and withstand in their own solutions. The results show that at a concentration of soda and potash solutions Rj> O _oi u ,. above 25 g / l, the samples disperse. The most durable are samples with water.

The proposed method is efficient and economical, of great environmental importance, since it completely allows you to clean the environment from dust, prevents the loss of raw materials, which can be completely used for cement production, and reduces material costs.

Claims (1)

Claim The method of purification of dust from cement production from cement production, including humidification of gases with water and subsequent cleaning in electrostatic precipitators, is also distinguished by the fact that, in order to increase the degree of purification and the possibility of using trapped dust in cement production, the gases after electrostatic filtration are treated with sodium carbonate solutions or potassium, or a mixture thereof at a concentration of R _a O _oBut equal to. 30 - 100 g / l, followed by filtration to achieve W: T = 7: 1 - 10: 1. and washing the obtained precipitate at W: T = 2: 1 - 5: 1.