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3DEVELOPMENT OF A HIGHLY SAVING TECHNOLOGY FOR PURIFYING NATURAL GAS FROM SULFUR-CONTAINING COMPOUNDS
Jumaev K., Djunaidov Kh.
Bukhara Engineering - Technological Institute, Uzbekistan
DOI: 10.5281/zenodo.7479804
ABSTRACT
Ensuring the reliability of operation and production safety of oil and gas facilities in modern society is the most important task. Recently, interest has appeared in the use of reagent less methods to reduce corrosive activity and to change the rheological properties of transported water and water-oil mixtures, for example, the use of physical influences. In particular, processing of permanent and variable magnetic field of liquids transported through pipelines allows changing their corrosive and rheological properties.
Keywords: absorber, desorber, oil gases, gas separator, heat exchanger, air cooler, vortex.
Parameters and final results of technological processes of oil refining and petrochemical enterprises are determined by the quality of raw materials supplied for processing. The quality of raw materials, in turn, depends on the effective use of methods of its preparation and cleaning. The current stage of hydrocarbon chemistry and technology is characterized by the deterioration of its properties and quality due to the increase in oil hydration, corrosion activity, sulfur and salt content. From this point of view, reducing the impact of the above-mentioned negative factors of hydrocarbon raw materials is one of the promising directions of science and technology.
The composition of extracted natural gas consists mainly of (SnN2n+2) saturated hydrocarbons of the methane series. Most of these gases are methane and ethane. Other hydrocarbons, including propane, butane, pentane, and hexane, are also present in small amounts. In addition, there will be hydrocarbon components: oxygen (O), sulfur (S), nitrogen (N), carbon dioxide gas, hydrogen sulfide, helium, argon, and water vapor.
In industry, such additives are usually separated using large-scale absorption devices. This leads to higher capital costs and operating costs. One of the promising ways to solve this problem is the use of small compact absorption devices. [1]
The absorber is a multi-functional device, which mainly consists of three parts: separation, exchange and filtering parts. The separation part is designed to separate the droplet absorbent from natural gas. In the exchange part, the acidic components of the satellite oil gas are separated by absorption into the absorbent. In the filtering part, the droplet-shaped absorbent remaining in the purified gas is separated. [2,3]
An experimental device was assembled to study the efficiency of the mass exchange process in a packed absorber. Satellite gas with the following physical parameters was used in the experiment: density 1.1 kg/m3, pressure 0.22 MPa, molar mass 23.895 g/mol, N2S concentration 1.66 g/m3. Accompanying petroleum gases were stripped of N2S with a 7% NaOH aqueous solution.
Figure 1. Scheme of the experimental device
The experimental device (Fig. 1) consists of the following parts: 1, 4, 8, 9, 10, 13, 15 - adjusting bodies; 2, 16 - MP type manometers; 3 - SG75M gas meter; 5, 14, 17 - sampling points; 6 - drum device; 7 - liquid meter; 11 - clean absorbent liquid container; 12 - used absorbent liquid container; 18 - NSC-500/50 type centrifugal pump.
A single-stage rectilinear drum apparatus was prepared as a mass exchange apparatus (Fig. 2). Apparatus body (1), tangential plate drill with separator installed in the center of the body (3), 1 mm. central tube (2) for transfer of absorbent liquid with diameter 24 holes, 50 mm. diameter tangential gas inlet nozzle (4), spent absorbent liquid outlet nozzle (5), fresh gas outlet nozzle (6).
a) sketch; b) in aggregate; c) installed state in the experimental device, 1-case; 2- pipe, 3- VKU, 4, 5, 6-nozzles, height of placement of N- gas inlet nozzle.
The purpose of the experiments is to determine the efficiency of the exchange of substances. The data obtained as a result of the experiment are presented in Table 1. Experiments show that as the gas velocity increases in the zone of the rotating plates, the
efficiency of mass exchange increases. This depends on the height of the gas inlet tangential nozzle. [4,5,6]
The highest efficiency was Eu = 0.863 at H/d and L/G = 2.5. As the loading on NaOH aqueous solution increases to L/G = 3, the mass exchange efficiency increases to Eu = 0.946.
Ey = 0,0081V3 -0,1008V +1,0675
Table 1
Experimental results of the study of the efficiency of mass exchange in a piled absorber
variants Gas consumption, Qg nm3 /s Loading ratio, L/G NaOH consumption, Qs m3 /s B ° „. io ^ u • m « B 3 s 5 ^ «S m w (N K Mass of NaOH passed through H2 S, m, g The concn of H2 S in NaOH. r/n Mass of H2 S absorbed into NaOH, m, g S CN k Metabolic efficiency
H=50 mm 260 2,5 0,655 1,66 14,4 0,57 12,43 0,227 0,863
H=100 mm 260 2,5 0,655 1,66 14,4 0,53 11,6 0,323 0,805
H=150 mm 260 2,5 0,655 1,66 14,4 0,5 10,9 0,404 0,757
H=50 mm 260 3 0,786 1,66 14,4 0,52 13,62 0,090 0,946
Based on the obtained results, the dependence of the mass exchange efficiency (L/G = 2.5) on the gas velocity was determined (Fig. 3).
I»ypoiiMH nnacTHHanap soHaciira Kiipmiizia ra3 Teajrara, V \t/c
Figure 3. Dependence of mass exchange efficiency (L/G = 2.5) on gas velocity
As can be seen from the figure, the efficiency of mass exchange increases with the increase of gas velocity (when the height of the gas inlet nozzle decreases). Based on the conducted experiments, the law of dependence of the efficiency of mass exchange on the height of the nozzle was determined in the mass absorber with a diameter of 50 mm tangential tube.
Eu = 0.0081(-0.00041N2 + 0.0362N+ 9.075)2 -0.108(-0.0004N2 + 0.0362N+ 9.075) 1.0675
It is desirable to introduce a small-sized, highspeed lumped absorber in order to reduce the technological equipment, their overall dimensions and metal costs, and, of course, the capital costs necessary for the preparation, installation, operation and maintenance of the device.
Table 2
Hardware specifications comparison chart
Parameters Column with nozzle Stackable absorber
Gas consumption, nm3 /h 8700 8700
Ratio of mass loads, kg/kg 3 3
Working pressure, MPa 0,2 0,2
Rotation speed, m/sec 1,919 -
Gas velocity in the apparatus, m/sec 1,439 20
Hydraulic resistance, MPa higher than 0,01 higher than 0,01
Height, m 10 3
Diameter, m 1,6 1
Number of devices, pcs 1 1
Comparing the characteristics of the devices (Table 2) shows that the overall dimensions of the piled device - diameter and height are significantly smaller than the dimensions of the tubular column - demonstrate the advantage of the proposed device. In addition, if a lumped absorber is used, there is no need for a gas separator installed in the system with a height of 4.5 m and a diameter of 1.6 m. [4,5,6]
Based on the conducted research, a technological system for purifying natural gas from sulfur compounds was developed (Fig. 6). The system consists of the following parts: A- absorber; S- gas separator; E-storage tank; X- refrigerator; T- heat exchanger; AVO - air cooler; N- pump; VA is a rolling machine.
Figure 4. Proposed technological scheme of natural gas purification
In this figure, the existing process system and the proposed process scheme with a small size absorber are placed side by side, and the comparison clearly shows the advantage of the new system. As a result of the research, the following can be concluded:
1. Based on the analysis of the effectiveness of existing absorption devices and taking into account their shortcomings, it is promising to use a lump
absorber, which is free of disadvantages such as multiple objects, large dimensions and high metal costs, in the purification of natural gas from hydrogen sulfide.
2. The use of lumped absorbers makes it possible to realize aggregation, that is, to create an absorber in the form of a multifunctional aggregate. It is known that in the lump absorber, the gas-containing liquid is first
separated, and in the next section, the process of substance exchange takes place. This section is separate from the initial separation section and consists of several contactors. In the stack absorber, the gas is removed from the absorbent liquid in the final section.
3. A comparison of different versions of the lumped absorber with the nozzle placed at different heights showed that in all variants the full speed increases from the axis of the lumped device towards the edge, while the speed in the zone of the plates decreases rapidly.
4. It was found that the appearance and character of the full speed distribution graph does not change with the increase in the height of the nozzle. Therefore, it is not advisable to increase the location of the faucet.
5. By carrying out experiments in the experimental device, the law of dependence of the mass exchange efficiency on the height of the tangential pipe twisting surface was studied, and it was determined that the highest efficiency in the constant consumption of gas is at H=d.
6. It was found that the efficiency of mass exchange increases with the increase of gas velocity in the zone of the rotor plates. This is done by adjusting the height of the gas inlet tangential nozzle. The highest efficiency was Eu = 0.863 at H/d and L/G = 2.5. As the loading on NaOH aqueous solution increases to L/G = 3, the mass exchange efficiency increases to Eu = 0.946.
7. Based on the conducted experiments, the law of dependence of the efficiency of mass exchange on the height of the nozzle in a lumped absorber with a tangential tube diameter of 50 mm was determined.
8. It is advisable to introduce a small-sized, highspeed drum device in order to reduce the technological devices, their overall dimensions and metal costs, and of course the capital costs necessary for the construction, operation and maintenance of the device.
The comparison of the characteristics of the devices shows that the overall dimensions of the piled device - diameter and height are significantly smaller
than the dimensions of the column with a tube -demonstrate the advantage of the proposed device. In addition, if the drum device is used, there is no need for a gas separator installed in the system with a height of 4.5 m and a diameter of 1.6 m.
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