TECHNOLOGICAL REVIEW FOR USING POLYACRYLIC MEMBRANES IN FLUE GAS UTILIZATION

ABSTRACT

The article provides information on optimizing the operating mode of technological furnaces, increasing efficiency by utilizing the heat of flue gases and data on reducing fuel consumption for technological purposes. The maximum efficiency of technological furnaces of primary oil refining installation was increased until 70.68% by optimization of the combustion process. For further increment of efficiency, the following technological changes have been made: 1) Utilization of heat to lower flue gas’s temperature, and then capturing harmful and greenhouse gases; 2) Creation of an information system for calculating and predicting the composition of flue gases by analyzing the content of nitrogen and sulfur in fuel oil and technological fuel gas. A technological scheme for utilization of flue gases from primary oil refining furnaces is proposed.

АННОТАЦИЯ

В статье представлена ​​информация по оптимизации режима работы технологических печей, повышению КПД за счет использования тепла дымовых газов и данные о снижении расхода топлива на технологические цели. Максимальный КПД технологических печей установки первичной переработки нефти увеличен до 70,68% за счет оптимизации процесса сжигания. Для дальнейшего повышения эффективности проведены технологические изменения: 1) Использование тепла для снижения его температуры, а затем улавливание вредных и парниковых газов; 2) Создание информационной системы для расчета и прогнозирования состава дымовых газов путем анализа содержания азота и серы в мазуте и технологическом топливном газе. Предложена технологическая схема утилизации дымовых газов печей первичной переработки нефти.

Keywords: greenhouse gas emissions, membrane for capturing CO₂, capacity, technology, utilization, flue gases

Ключевые слова: выбросы парниковых газов, мембрана для улавливания СО₂, мощность, технология, утилизация, дымовые газы.

Harmful greenhouse gases and aerosols resulted from the combustion of fuel oil with heteroorganic compounds: a mixture of gases containing sulfur oxides, carbon dioxide, carbon monoxide, nitrogen oxides, fine dust particles, water vapor, unburned hydrocarbon gases, nitrogen, unreacted oxygen, etc [1, p.330]. Along with the smoke gases, very high heat is also released into the environment. The emitted acidic gases are hydrated in the atmosphere and return to the earth, resulting in damage to the environment and human health [2, p.999; 3, p.1]. Harmful exhaust gases emitted into the environment by enterprises operating on the basis of old technologies have a negative impact on the health of the population in the vicinity of the enterprise and, ultimately, on the environment of the country and the globe. The global warming process, i.e. the "greenhouse effect", is caused by the increase in the concentration of carbon dioxide, carbon monoxide, methane and similar heat trapping gases in the air during their mining, processing and combustion. Moreover, the rapid depletion of fossil energy sources, as well as with the increase of harmful gases, the emergence of many diseases that were not in the previous time have occurred and this procedure is being a serious concern to the whole world [4, p.15; 5, p.1]. In this paper, scientific development has been proposed for the introduction of energy-saving technology in the primary oil refining and automation of the calculation of the combustion process in the furnaces used in this process. In order to use of industrial furnaces, including oil refining furnaces, efficiently, the introduction of the following three-stage technological additions and changes was conducted:

 a. Optimization of working conditions;

 b. Efficient use of heat output;

 c. Waste recycling.

From the table 1, it can be seen that the concentration of this gas in the atmosphere has increased by 36.41% over the last 100 years [6, p.60]. The situation is also having a negative impact on the economy, as they are increasing health care costs and taking away with them raw materials that are valuable for other production.

As we know, almost all fuels that are burned in oil refineries’ furnaces, e.g. fuel oil or technological gas, consist of heterorganic compounds. Some reactions of fuel oil and gas combustion process are as follows: (pentadecane) C₁₅H₃₂ + 23O₂ à 15CO₂+16H₂O, (ethane) C₂H₆+3.5O₂ à 2CO₂+3H₂O, (hydrogen sulfide) 2H₂S+3O₂ à 2SO₂+2H₂O, (thiophene) C₄H₄S+6O₂ à 4CO₂+2H₂O+SO₂, (pyridine) 2C₅H₅N + 14.5O₂ à 10CO₂ + 5H₂O+2NO₂, (sulfide) C₈H₁₇-S-C₇H₁₅ + 24O₂ à 15CO₂ + 16H₂O + SO₂, (phenol) C₆H₅OH + 7O₂ à 6CO₂+3H₂O etc.) oxidation reactions take place.

Table 1.

Basic parts of dry air by volume.

Methods

The method of testing nitrogen content of fuel oil

Nitrogen content of fuel oil and technological fuel gas is determined according to the methodology and instrumentation mentioned in the literature [7, p.1]

The method of testing sulfur content of fuel oil

Standard test method is used to define sulfur content of fuel oil [8, p.1]. The determination of sulfur content of technological fuel gas is not needed as it is treated with diethanolamine before the combustion.

The method of predicting flue gas composition

Information system was created to calculate for predicting the composition of flue gas derived from after combustion of fuel oil and technological gases. It was performed by means of Excel [9, p.620]. The information system was given as an electronic appendix to this paper.

Results and discussion

Prediction process of flue gas composition.

Firstly, created an information system that calculates the material balance of the process of combustion of the primary technological furnace, where fuel oil and technological fuel gases are combusted, on the technological installation ELOU-AVT-2/3 of Fergana Refinery.  At the same time, using standard methods for determining the composition of fuels, it was possible to determine the amount of nitrogen and sulfur and predict the amount of toxic anhydrides released during combustion.  If the emissions of toxic and greenhouse gases are higher than the norm (maximum allowable emissions), the system indicates it (colored red for SO₂, brown for NO, green for NO₂ see electronic application or Table 2). The highest efficiency of the furnaces of primary oil refinery could be achieved by optimization just until 70.68% [10, p.105]. For further increment of the efficiency technological additions has to be implemented [6, p.60; 11, p.34].  The technological schemes for the process are referred as Figure 1 and Figure 2.

The definition of technological scheme.  This is a closed system, close to ideal, i.e. here is only the entry of raw materials and the output of the finished product, the losses are minimized. In order to utilize the heat of the flue gases emitted into the atmosphere at a temperature of 370 ^oC, heat recovery utilizer and recuperator are used to obtain live steam and hot air for technological use, thereby lowering the temperature of the flue gases to 105-115 ^oC. The developed live steam moves through the serpentine tubes inserted into the 19/19¹ - adsorbers, heats the membrane to 70 ^oC, which breaks the chemical bond formed by the CO₂ and the membrane, and allows pure CO₂ to be obtained. A temperature swing desorbing mode under vacuum was selected for the desorption process. The heat of this live steam being produced meets the need for heat in the installation. The flue gases enter the 10 - mixer with ozone. Oxidized gases are acidic gases that are easily absorbed by the absorbent. The fully oxidized flue gases then transfer their heat to the water of 11 - economizer (or process deaerator water) for heating. Acidic oxides are absorbed into the condensate along with ammonia, leaving the devices in a neutral environment that does not degrade, and sent to the stable fertilizer production unit. Uncondensed flue gases enter the 12 - scrubber at a temperature of 40-70 ^oC, where they are also washed with ammonia water (pH = 5-10). Stable fertilizers NH₄NO₃ and (NH₄)₂SO₄ are obtained from the formed unstable NH₄NO₂ and (NH₄)₂SO₃ salts. The non-condensed gases are sucked out of the separator through the 13 - drip eliminator by means of a 5¹ - smoke exhauster and fed to the 14 - compressor, from there to the 15 - absorber, or without entering it to the 19/19¹ - adsorber. In the 15 - absorber, SO₂ in the flue gases is absorbed using a 30% limestone solution. As a result, the production of gypsum - CaSO₄ from limestone CaCO₃ is launched. Smoke gases containing mainly nitrogen - N₂, O₂, CO₂, H₂O and small amounts (<2 ppm) of other acidic oxides pass through the PAM layer of the 19/19₁-adsorber, where the CO₂ in the flue gas is trapped. The 19/19¹ - adsorber contains PAM and operates periodically alternating with the 19¹/19 - desorber. For desorption, the internal pressure of the desorber is reduced to ≤100 mbar_abs by means of 8²-vacuum pump, and using live steam the pipes inserted into the desorber’s jacket and the membrane are heated gradually to 70 ^oC. The desorbed CO₂ cooled using an 16¹ - aqueous cooler, and sent to 20 - compression section, then to the intended use, e.g., dry ice, acrylic acid production unit and other petrochemical production units. In the above-mentioned furnace, if only desulfurized technological gases are used, SO_n, N_xO_y gases and aerosols are almost absent in flue gases, in this case the scrubber is not supplied with ammonia water, flue gases enter to the 19/19¹ - adsorber bypassing 15 – absorber.

Table 2.

Material balance of the combustion process in furnaces of Oil Refinery

^{PDV – maximum permissible emission}