RU2535473C1 - Production procedure of petroleum coke with low content of sulphur oxides in combustion gases - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the production procedure of petroleum coke with a low content of sulphur oxides in combustion gases, which is based on usage of substances binding sulphur. High-sulphur petroleum coke is saturated with an aqueous dispersion of shale-based substance binding sulphur, stirred up thoroughly to a paste-like state, water is evaporated at a temperature of 120-150°C up to the permanent weight and then cooled down.

EFFECT: reducing the sulphur oxide content in combustion gases.

6 cl, 1 dwg, 4 tbl, 3 ex

Description

The invention relates to methods for producing coal products, in particular petroleum coke, with a reduced content of sulfur oxides in combustion fumes by introducing sulfur-binding additives.

A known method (application WO 01/25373 A1, 04/12/2001, C10L 9/10) for the production of coal products with low sulfur content, which consists in grinding coal in the form of a powder with a particle size of 20 ÷ 80 mesh, mixing it with hydrated lime, adding water so that the humidity is 10-30% vol. the total mass of granules, the placement of powder, hydrated limestone and water in a container and heating to a temperature of 149 ÷ 205 ° C in an open container until the moisture content is less than 10% vol.

A known method of binding sulfur contained in coal products (in particular, brown coal) in solid combustion residues is based on the use of sulfur-binding substances, mainly CaO or MgO, while crushed and sometimes pre-dried brown coal and sulfur-binding substance are mixed to a state in which the substance in the mixture is in dispersed form (DE 3319086, C10L 10/04, 12/06/84).

The disadvantage is the inability to achieve optimal combustion conditions. It should also be noted that suitable combustible substances that are inert from the point of view of sulfur bonding alone cannot or are very poorly briquetted. Uniform grinding of the entire mixture is achieved using a mixer, which can be technically difficult.

A known method of bonding part of the sulfur from coal products (coal or mixtures of hard and brown coal), in which coal or mixtures of brown and hard coal is mixed with a substance that binds sulfur to a state in which this substance in the final mixture is present in finely divided form (DE 3326826, C10L 10/04, 02/14/85).

The disadvantage is that with a large number of sulfur-binding additives, sulfur oxide emissions are quite high.

This technical solution is taken as a prototype. However, the prototype has the same disadvantages as its analogues, namely, the emission of sulfur oxide, although with a small percentage, occurs. The disadvantage of this method is the high cost of the proposed additives that bind sulfur oxides in the combustion gases.

The objective of the invention is to develop a method for producing petroleum coke with the achievement of the following technical result - reducing the content of sulfur oxides in flue gases.

The problem is solved in that in the method for producing petroleum coke with a low content of sulfur oxides in combustion fumes, based on the use of sulfur-binding substances, according to the invention, sour petroleum coke is impregnated with an aqueous dispersion of sulfur-binding substance, thoroughly mixed to a paste-like state, the water is evaporated at a temperature of 120-150 ° C to constant mass and cooled, while shale, semi-coke or shale ash are used as a sulfur binder.

The method is carried out by the following sequence of operations: sour petroleum coke and shale, shale semi-coke or shale ash is ground in a ball mill to a particle size of less than 1.3 mm; prepare an aqueous dispersion of shale, shale semicoke or shale ash with a substance content of up to 20% wt. To stabilize the dispersion, the introduction of stabilizers is allowed. Next, a mixture of petroleum coke and a freshly prepared aqueous dispersion of shale, shale semi-coke or shale ash is carried out for at least 1 hour. Sour petroleum coke is taken in a weight ratio of 0.5: 1.0 to 1.0: 1.0 with an aqueous dispersion of shale shale semicoke or shale ash. The resulting carbon paste is evaporated to dryness at a temperature of 120-150 ° C to constant weight and cooled.

In order to more evenly distribute the additive of shale, shale semicoke, or shale ash in petroleum coke, it is recommended that the additive be introduced in several successive stages so that the final additive content in the coke sample is from 5 to 15% wt .; Each subsequent step of introducing the additive into the sample is accompanied by stirring, evaporation of water and cooling.

The choice of slate and its processing products - shale semi-coke and shale ash as the basis for the impregnating material is due to the presence of active substances (alkaline earth metal oxides) in their composition, which during the coke combustion form a stable chemical compound with sulfur, passing into slag. By converting organic sulfur to a stable mineral compound, the amount of sulfur oxides in the flue gas is reduced.

Impregnation of sour coke with an aqueous dispersion of shale, shale semi-coke and shale ash reduces the sulfur content in the combustion gases, and the described method allows to obtain environmentally friendly energy fuel.

Method implementation examples

Example 1. In 4 porcelain crucibles (together with a glass rod for each), the test sample of petroleum coke of the Novokuybyshevsky Oil Refinery, previously crushed in a ball mill and sieved through a sieve with a particle size of less than 1.3 mm, sulfur content of 5.8% by weight, is weighed the yield of volatile substances 8% wt .; then a 10% aqueous dispersion of shale of the Baltic field, the characteristics of which are presented in table 1, is introduced into the crucibles; thoroughly mixed with a glass rod to a pasty state for at least 10 minutes; evaporate water at a temperature of 120-150 ° C to constant weight; then the crucibles are cooled and transferred to a desiccator; after stabilization of the mass, the crucibles are weighed.

The introduction of additives in compliance with the entire sequence of operations described previously, is carried out until the weight gain of the added additive to the original sample will be at least: for crucible No. 1 - 2% wt .; for crucible No. 2 - 4% wt .; for crucible No. 3 - 6% wt .; for crucible No. 4 - 8% wt. The results for reducing sulfur in flue gas combustion are presented in table 3.

Example 2. The described method for producing coal products with a low content of sulfur oxides in the combustion flue gas is carried out under all conditions of Example 1, except that shale semi-coke prepared by coking of shale at a temperature of 520 ° C is used as a sulfur binding substance. The results for reducing sulfur in flue gas combustion are presented in table 3.

Example 3. The described method for producing coal products with a low content of sulfur oxides in combustion fumes is carried out under all conditions of Example 1, except that as a substance that binds sulfur, use shale ash obtained by burning shale at a temperature of 850 ° C to complete ashing, ash characteristics are presented in table 2. The results on sulfur reduction in combustion flue gases are presented in table 3.

The figure shows the change in the yield of sulfur with combustion products in terms of the mass of coke at various concentrations of additives in the coke.

The data show that the impregnation of sour coke with the considered additives can reduce the sulfur content in the combustion gases, and most effectively with the use of additives based on shale. With its involvement in raw materials in the amount of 8.6% wt. the sulfur content in the combustion gases decreases from 5.8% wt. up to 0.8% wt. in terms of the mass of coke In the case of the introduction of coke additives based on shale semi-coke - the residual product of the processing of shale, in the amount of 9% wt. - sulfur emissions are reduced to 2.2% wt. in terms of the mass of coke. The addition of shale ash in the amount of 9.5% wt. reduces the sulfur content in the combustion gases - up to 2.9% wt. in terms of the mass of coke. The sulfur content in the combustion gases of the initial coke of the Novokuybyshevsk refinery without additives amounted to 5.8% wt.

The effectiveness of reducing emissions of sulfur oxides with combustion gases of coke with various additives is presented in table 4.

As can be seen from the data in table 4, the maximum possible reduction in emissions of sulfur oxides with combustion gases is achieved by involving additives based on shale: at 5% wt. the efficiency is 32.8% rel., with 9% wt. - 86.0% rel. As a result of impregnation of sour coke with aqueous dispersions of shale semicoke and shale ash in an amount of 5% wt. efficiency is 22.4% rel. and 17.2% rel. respectively, at 9% wt. respectively 58.6% rel. and 46.6% rel.

The effectiveness of shale semicoke and shale ash can be explained by a decrease in the effect of the transport of the active substance - an alkaline earth metal compound to the combustion surface, which is produced by shale hydrocarbons, as well as by the content of sulfur mineral compounds - sulfates and, as a consequence, a lower content of the active substance in the composition of semicoke and ash.

In the process of coke combustion, phenomena can occur that enhance the active action of the components included in the shale, which lead to more complete contact of the coke with the active substance and a decrease in sulfur compounds in the combustion gases.

Studies on the combustion (oxidation) of the initial high-sulfur coke and coke impregnated with an aqueous dispersion of shale and shale semicoke showed a higher reactivity to oxygen and a higher burning rate. This fact allows us to judge that under identical conditions in the furnace part of energy furnaces, the combustion of saturated coke samples with the addition of shale and shale semicoke will be more complete than the initial coke, which will increase the overall efficiency of the furnace.

Table 1 Characteristics of oil shale of the Baltic field Options Humidity W,% wt. Ash A,% wt. Sulfur S,% wt. Fischer semi-coking yield on dry shale,% wt. The fractional composition of the oil,% wt. Pyrogenetic water Resin Semi-coke gas nk - 200 ° C 200-360 ° C > 360 ° C 2,3 50.8 1.8 0.9 21.0 71.8 6.3 16 34 fifty

table 2 The chemical composition of oil shale ash SiO ₂ Al ₂ O ₃ TiO ₂ CaO MgO Fe ₂ O ₃ Cr ₂ O ₃ MnO SO ₃ Na ₂ O K ₂ O 25.6 6.6 0.4 30.7 2,3 5,0 0.01 0,03 2.6 0.4 0.8

Table 3 Reducing the sulfur content in the combustion gases of sour coke with various additives Options Type of additive Mass of coke, g Additive weight, g The content of additives,% wt. The output of sulfur with combustion gases,% wt. to coke No additives - - - 5.80 Slate (example 1) 7.16 0.21 2.95 4.94 7.20 0.33 5.18 3.78 7.13 0.53 7.47 1.81 7.17 0.62 8.58 0.81 Shale semicoke (example 2) 6.99 0.16 2,36 5.52 6.97 0.39 5.64 4.17 6.98 0.49 7.03 3.32 7.00 0.64 9.14 2.15 Shale Ash (Example 3) 7.15 0.19 2.68 5.60 7.43 0.45 6.06 4,50 7.24 0.50 6.95 4.00 7.00 0.67 9.60 2.90

Table 4 The efficiency of reducing emissions of sulfur oxides with combustion gases,% Rel. Options Type of additive at 5% wt. additives at 9% wt. additives Slate (example 1) 32.8 86.0 Shale semicoke (example 2) 22.4 58.6 Shale Ash (Example 3) 17,2 46.6

Claims (6)

1. A method of producing petroleum coke with a low content of sulfur oxides in combustion fumes, based on the use of sulfur-binding substances, characterized in that high-sulfur petroleum coke is impregnated with an aqueous dispersion of sulfur-binding substance, based on shale, thoroughly mixed to a paste-like state, evaporated water at a temperature of 120-150 ° C to constant weight and cool. 2. The method according to claim 1, characterized in that as a substance that binds sulfur, shale is used. 3. The method according to claim 1, characterized in that as a sulfur binding substance, shale semicoke is used. 4. The method according to claim 1, characterized in that as a substance that binds sulfur, shale ash is used. 5. The method according to claim 1, characterized in that use sour petroleum coke with a particle size of less than 1.3 mm 6. The method according to claim 1, characterized in that the sour petroleum coke is taken in a mass ratio of from 0.5: 1.0 to 1.0: 1.0 with an aqueous dispersion of a sulfur-binding substance based on shale.

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