Calculation and design of the nozzle absorber

Contents

Introduction

Selection of structural material of the apparatus

Process calculation

Hydraulic calculation

Constructive calculation

Mechanical calculation

Conclusion

Bibliographic list

Introduction

The exchange rate project considers the absorption process. Absorption is the process of absorbing gases or vapors from gas or vapor-gas mixtures by liquid absorbers (absorbers).

In physical absorption, the absorbed gas (absorbent) does not react chemically with the absorbent. If the absorbent forms a chemical compound with the absorbent, then the process is called chemosorption.

Physical absorption is reversible in most cases. This property of absorption processes is based on the separation of absorbed gas from the solution - desorption.

Absorption processes are widespread in chemical technology and are the main stage of a number of important industries (for example, SO3 absorption in sulfuric acid production; absorption of HCl to obtain hydrochloric acid; absorption of nitrogen oxides by water in nitric acid production; absorption of vapors of various hydrocarbons from petroleum refining gases, etc.). In addition, absorption processes are the main processes in the sanitary purification of exhaust gases released into the atmosphere from harmful impurities.

Devices in which absorption processes are carried out are called absorbers. Like other mass transfer processes, absorption takes place at the phase interface. Therefore, absorbers must have a developed contact surface between liquid and gas. According to the method of forming this surface, absorbers can be conventionally divided into the following groups :

1) surface and film;

2) nozzle;

3) bubbling (poppet);

4) spraying.

Widespread industrial use as absorbers

received columns filled with packing - solids of various shapes. In the packing column (Fig.1), the nozzle 1 is laid on support grates 2 having holes or slots for gas and liquid flow. The latter, with the help of distributor 3, uniformly irrigates the nozzle bodies and flows down. Throughout

the height of the nozzle layer does not generally achieve a uniform distribution of liquid across the column section, which is due to the wall effect - a higher density of packing in the central part of the column than at its walls .

As a result, the liquid tends to flow from the central part of the column to its walls. Therefore, in order to improve the wetting of the nozzle in larger diameter columns, the nozzle is sometimes laid in layers (sections) 2-3 m high and liquid redistributors 4 are installed under each section except the lower one.

In the packing column, liquid flows through the packing element in the form of a thin film, so the contact surface of the phases is mainly a wetted surface of the packing, and the packing devices can be considered as being of different kinds to the film. However, in the latter, the film flow of liquid occurs over the entire height of the apparatus, and in the nozzle absorbers - only over the height of the nozzle element. When liquid flows from one nozzle element to another, the liquid film is destroyed, and a new film is formed on the underlying element. At the same time part of liquid passes through new layers of nozzle located below

in the form of jets, drops and splashes.

Selection of structural material of the main set

The following requirements apply to structural materials when manufacturing devices:

1. Sufficient general chemical and corrosion resistance of the material in an aggressive medium with a given concentration, temperature and pressure, at which the technological process is carried out, as well as resistance against other possible types of corrosion destruction (intergranular corrosion, electrochemical corrosion of conjugated metals in electrolytes, corrosion under stress, etc.);

2. Sufficient mechanical strength at the given pressure and temperature of the process, taking into account the specific requirements for testing the devices for strength, tightness, etc., and in operational conditions when acting on the devices of various kinds of additional loads (wind load, deflection from own weight, etc.);

3. The best ability of the material to be welded with high mechanical properties of the welded joints and their corrosion resistance in an aggressive environment, to be treated by cutting, pressure, bending, etc.;

4. Low cost of material, not shortage and mastery of it by industry. Double-layer steels, non-metallic materials, non-metallic coated steels should be used.

Since CO2 is not an aggressive substance, alloyed steel 12X18N10T (GOST 552079) can be used as a structural material for the main parts and housing of the nozzle absorber.

The inert gas in the mixture is air, which is an aggressive substance that causes corrosion of metals.

Conclusion

According to the assignment, the nozzle absorber was calculated and designed. As a result of optimization, the optimal nozzle was chosen with the lowest cost - Rashig ceramic rings 50x50x5.

The actual flow rate of the absorber is 1.04 times the minimum. The actual gas velocity in the absorber is 25.09% of the limit speed.

The diameter of the absorber is 1000 mm, the height of the nozzle is 9.1696 m, the height of the cylindrical part of the absorber is design - 12.6864 m.

The nozzle is laid in 2 layers.

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