RU2490318C1 - Method for reduction of hazardous emissions from burners with flame combustion - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to method for reduction of hazardous emissions from burners with flame combustion that includes supply of absorbent to burner and collection of used absorbent; the method is distinguished by absorbent delivery into flue gases formed in the post-flame area in quantity of 5-7% of fuel consumption.

EFFECT: reduction of hazardous emissions into atmosphere, in particular sulphur oxides, and improvement of operating economy and reliability of a boiler unit.

1 cl, 1 ex

Description

The invention relates to methods for cleaning gases from harmful substances generated by the combustion of both solid and liquid and gaseous fuels.

A known method of reducing harmful emissions resulting from the combustion of fuel, including the supply of natural zeolites (clinoptilolite composition (Na ₂ K ₂ ) · O · Al ₂ O ₃ · 10SiO ₂ · 8H ₂ O) inside the boiler mixed with fuel before burning (see RF patent No. 2057165, IPC C10L 9/10, C10L 10/00, publ. 03/27/1996).

Closest to the claimed is a method of reducing harmful emissions from burning coal in fluidized bed furnaces, in which the coal is burned together with pre-loaded inert material, such as sand or fireclay, with the addition of natural zeolites as an additive to reduce emissions of harmful substances, in particular oxides sulfur (see RF patent No. 2421505, IPC C10L 10/00, publ. 06/20/2011, bull. No. 17).

The disadvantages of the known methods of reducing harmful emissions is the high consumption of adsorbent, as well as a decrease in the efficiency of the boiler unit due to increased fuel ballast due to the addition of additives.

The technical result of the invention is to reduce emissions of harmful substances into the atmosphere, in particular sulfur oxides, as well as improving the efficiency and reliability of the boiler unit.

The result is achieved in that the method of reducing harmful emissions from combustion furnaces with flaring fuel, including feeding adsorbent to the furnace and collecting spent adsorbent, is characterized in that the adsorbent is produced in the flue gases generated in the after-flame zone of the boiler in an amount of 5-7% of fuel consumption.

The essence of the proposed method lies in the fact that produce a continuous supply of adsorbent in the flue gases formed in the after-flame zone of the boiler, in the amount of 5-7% of fuel consumption.

During the operation of the boiler, adsorbent (natural zeolites, alumina, ash) is continuously supplied to the flue gases formed in the after-flame zone of the boiler, using, for example, devices for shot blasting of heating surfaces or directly blowing it into the boiler lowering shaft, as well as due to devices of the above system collect the spent sorbent and withdraw it from the gas treatment cycle.

Due to the absorption of the fraction of sulfuric acid vapor H ₂ SO ₄ contained in the flue gas, simultaneously with a decrease in the concentration of SO ₂ and SO ₃ in the combustion products, the temperature of the dew point of the flue gas decreases. At the same time, it becomes possible to operate a boiler unit with deeper cooling of the combustion products at the outlet, which improves the reliability of the operation of air heaters (a decrease in the probable corrosion rate in the temperature range of 80-120 ° C). In addition, lowering the temperature of the dew point of the flue gas in real conditions allows you to increase the efficiency of the boiler compared to working in normal mode (without using the proposed technology).

During the continuous supply of adsorbent to the flue gases formed in the after-flame zone and passing through the boiler lowering chamber, optimal thermochemical conditions are created for the adsorbent to absorb harmful emissions and the contact of the adsorbent with the combustion products becomes longer. Under the conditions of the proposed method of reducing harmful emissions from furnaces with flaring fuel, it is possible to use various dry adsorbents, such as natural zeolites, alumina, ash. In this case, the temperature of the flue gases at the outlet of the furnace does not decrease, therefore, the nominal (basic) mode of operation of the boiler is not violated.

The method is as follows.

After the boiler is started and its operating parameters are achieved, the adsorbent (natural zeolites, ash, alumina) is continuously fed into the flue gases formed in the after-flame zone of the boiler, the optimal amount of which in the particular case of using any particular adsorbent is determined from the condition of the economic minimum of costs associated with it method implementation:

$$\{\begin{array}{l}\underset{\mathrm{AND}\to \min }{b^{opt}=\lim f(\mathrm{AND})}\\ \mathrm{AND}=f({\mathrm{AND}}_{\mathrm{one}})+f({\mathrm{AND}}_2)+f({\mathrm{AND}}_3)+C\end{array}$$

where b ^opt is the relative adsorbent consumption optimal according to the technical and economic assessment;

And - the total cost of the method, rubles / year;

f (And ₁ ) - fuel costs;

f (And ₂ ) - the cost of the adsorbent supplied to the convection shaft of the boiler;

f (And ₃ ) - payment for the emission of sulfur oxides, which depends on the consumption of adsorbent;

The listed summands of total costs are a function of adsorbent consumption;

C - operating costs.

МДж/кг (2000 ккал/кг), W^р≈40%, A^р≈8,6%, S^р=0,3%). Дымовые газы подвергались очистке от вредных выбросов с помощью природного цеолита (клиноптилолит состава (Na₂K₂)·O·Al₂O₃·10SiO₂·SH₂O), который подавался в конвективную шахту через систему дробеструйной очистки поверхностей нагрева. Расход природных цеолитов поддерживался на уровне 5% от расчетного расхода топлива на номинальном режиме работы котла.Example. On the boiler BKZ-220-100F3 with flaring, coal of the Kharanorsk deposit was used ( $$Q_n^R\approx 12$$

MJ / kg (2000 kcal / kg), W ^p ≈40%, A ^p ≈ 8.6%, S ^p = 0.3%). Flue gases were cleaned from harmful emissions using natural zeolite (clinoptilolite composition (Na ₂ K ₂ ) · O · Al ₂ O ₃ · 10SiO ₂ · SH ₂ O), which was fed into the convection shaft through a shot peening system for heating surfaces. The consumption of natural zeolites was maintained at the level of 5% of the estimated fuel consumption at the nominal operating mode of the boiler.

As a result of this, a 49% decrease in the gross emission of sulfur oxides was achieved (from 149.2 g / s to 76.5 g / s), an increase in the gross efficiency of the boiler by 0.83% (from 90.87% to 91.7 %), a decrease in fuel consumption by 0.15 kg / s (from 16.21 kg / s to 16.06 kg / s), a decrease in flue gas temperature by 13 ° C (from 159 ° C to 146 ° C).

Thus, we can conclude that the invention allows to reduce emissions of sulfur oxides in boilers burning both solid and liquid and gaseous fuels, as well as to increase the reliability and efficiency of the boiler by reducing the cost of cleaning and operation of the boiler due to cost savings on zeolites and fuel.

Claims (1)

A method of reducing harmful emissions from furnaces with flaring fuel, which includes feeding the adsorbent to the furnace and collecting spent adsorbent, characterized in that the adsorbent is produced in the flue gases formed in the after-flame zone of the boiler in an amount of 5-7% of the fuel consumption.