Tower equipment is equipment used in the petrochemical industry, which allows for sufficient contact between gas-liquid or liquid-liquid phases and facilitates mass transfer between phases. Therefore, tower equipment is commonly used in production processes for unit operations such as distillation, absorption, desorption, gas humidification, and cooling. In this issue, the editor will talk to everyone about this.

1. Packing absorption tower

Packing absorption tower

Introduction:A packed tower is a mass transfer equipment that uses the packing inside the tower as the contact component between gas and liquid phases. The body of the packing tower is a vertical cylinder, with a packing support plate installed at the bottom. The packing is placed on the support plate in a disorderly or integrated manner. Install a packing pressure plate above the packing to prevent it from being blown by the rising airflow. The liquid is sprayed onto the packing from the top of the tower through a liquid distributor and flows down along the surface of the packing. Gas is sent from the bottom of the tower and distributed through a gas distribution device (small diameter towers generally do not have gas distribution devices). It then flows continuously in reverse flow with the liquid through the gaps in the packing layer. On the surface of the packing, the gas-liquid phase is in close contact for mass transfer. The packed tower belongs to continuous contact gas-liquid mass transfer equipment, and the two-phase composition changes continuously along the tower height. Under normal operating conditions, the gas phase is the continuous phase and the liquid phase is the dispersed phase.

Advantages:Large production capacity, high separation efficiency, low pressure drop, small liquid holding capacity, and high operational flexibility.

Disadvantages:The cost of filling materials is high; When the liquid load is low, it cannot effectively wet the surface of the packing, resulting in a decrease in mass transfer efficiency; Cannot be directly used for materials with suspended solids or prone to aggregation; It is not suitable for complex distillation processes such as feeding and discharging on the opposite side.

2. Plate distillation tower

plate distillation column

Internal flow conditions of plate distillation tower

Plate tower is a step-by-step contact gas-liquid mass transfer equipment, mainly composed of cylindrical shell, tray, overflow weir, downcomer, and liquid receiving tray.

Principle:The liquid relies on gravity to flow from the downcomer of the upper tray to the receiving tray of the lower tray, and then flows horizontally through the tray, and from the downcomer on the other side to the next tray. The function of the overflow weir is to maintain a certain thickness of liquid layer on the tray. Under the pressure difference, the gas passes through the gas channels (bubble caps, sieve holes, float valves, etc.) of each layer of the tray from bottom to top, dispersing into small streams of gas, and bubbling through the liquid layer of each layer of the tray. On the tray, the gas-liquid phase is in close contact, exchanging heat and mass. In a plate tower, the gas-liquid phase contacts step by step, and the composition of the two phases changes step by step along the tower height. Under normal operation, the liquid phase is the continuous phase and the gas phase is the dispersed phase.

3. Gas cooling tower

Gas cooling tower

Cooling tower function:The waste heat generated in industrial production processes is generally carried away by cooling water. The function of a cooling tower is to exchange heat between the cooling water carrying waste heat and the air inside the tower, transferring the waste heat to the air and dissipating it into the atmosphere. For example, in a thermal power plant, the boiler heats water into high-temperature and high-pressure steam, which drives the steam turbine to generate electricity. The waste steam generated by the steam turbine is discharged into the condenser, where it exchanges heat with the cooling water and condenses into water, which is then pumped back to the boiler for recycling. During this process, the waste heat from the exhaust steam is transferred to the cooling water, causing the water temperature to rise. The cooling water carrying the waste heat transfers heat to the air in the cooling tower and is discharged into the atmosphere through the air duct.

Application scope of cooling tower:It is mainly used in air conditioning cooling systems, refrigeration series, injection molding, leather making, foaming, power generation, steam turbines, aluminum profile processing, air compressors, industrial water cooling and other fields. The most commonly used industries are air conditioning cooling, refrigeration, and plastic chemical industry.

4. Sieve plate extraction tower

Sieve plate extraction tower

Tower plate structure

Characteristics of sieve plate extraction tower:Large processing capacity, simple structure, and low cost, widely used in chemical production processes. The flow structure of liquid-liquid two-phase inside the tower has a significant impact on mass transfer efficiency, while the flow structure of the continuous phase is closely related to the structure of the tower internals.

5. Packing extraction tower

Overall structure of packed extraction tower

Working Principle:The structure of a packed extraction tower is basically the same as that of a packed tower for distillation or absorption. Suitable packing is installed inside the tower, and the light liquid phase enters from the bottom of the tower and is discharged from the top of the tower; The heavy liquid phase enters from the top of the tower and is discharged from the bottom of the tower. During the extraction operation, the continuous phase fills the entire tower, while the dispersed phase is dispersed into droplets by the distributor and enters the packing layer, where it contacts and transfers mass with the continuous liquid phase.

6. Reciprocating sieve plate extraction tower

Reciprocating sieve plate extraction tower

Working Principle:The reciprocating sieve plate extraction tower is also known as the vibrating sieve plate tower. The tower is equipped with an extraction device with a central axis that oscillates back and forth with many sieve plates. The central axis drives the plate string to perform vertical reciprocating motion in the tower through the driving device at the top of the tower, thereby stirring and dispersing the two liquid phases flowing counter current in the tower. The amplitude and frequency of the reciprocating motion of the plate string can be adjusted. Due to its advantages such as large processing capacity, high efficiency, flexible operation, and simple structure, the reciprocating sieve plate extraction tower is widely used in industrial sectors such as pharmaceuticals, petrochemicals, wet metallurgy, and wastewater treatment.

7. Rotary sieve plate extraction tower

Rotary sieve plate extraction tower

Working Principle:The rotary table extraction tower is a tower type extraction equipment with mechanical stirring, which consists of three parts: an upper clarification section, a mixing section, and a lower clarification section. The mixing section is cylindrical in shape and is divided into a series of extraction chambers by a static ring baffle. A fixed turntable is located between the two static ring baffles and rotates together with the stirring shaft. During operation, the heavy phase (aqueous phase) and light phase (organic phase) enter from the top and bottom of the tower, respectively, and are in countercurrent contact inside the tower. Under the agitation of a fixed turntable, the dispersed phase forms small droplets, increasing the mass transfer area. After completing the extraction process, the light and heavy phases flow out from the outlets at the top and bottom of the tower, respectively.

8. F1 type float tower

F1 type float tower

Features:Due to its high production capacity, stable tray efficiency, flexible operation, low cost, and convenient maintenance and cleaning, it is widely used.

9. Bubble Tower

Bubble Tower

Working Principle:Usually used to bring vapor (or gas) into close contact with liquid to promote mass transfer between them. Inside the tower, there are multiple horizontal trays with several short tubes for steam (or gas) to pass through. Each tray is covered with bubble caps with gaps or small grooves at the bottom edge, and overflow pipes are installed. During operation, the liquid continuously enters from the upper part of the tower, descends plate by plate through the overflow pipe, and accumulates liquid layers on each plate, forming a liquid seal; Steam (or gas) enters from the bottom of the tower and disperses into small bubbles through the gaps or grooves on the bottom edge of the bubble cover. It fully contacts the liquid and passes through the liquid layer to reach the liquid surface, then rises to the upper tray. Short pipes installed inside the tower are called internal overflow type; There are also those installed outside the tower, called external overflow type. Bubble cap towers are widely used for distillation and gas absorption. The bubble cap tower has a high degree of flexibility in operation, and the trays are not easily clogged. However, the structure is complex, the cost is high, the liquid layer on the tray is thick, the pressure drop on the tray is large, and the production capacity and tray efficiency are low.

10. Turbulent ball tower dust collector

Turbulent ball tower dust collector

Principle:When a certain amount of polyethylene spherical packing is placed inside the tower and the gas velocity reaches a certain value, the small balls suspend and vigorously rotate and collide with each other, achieving the effects of mass transfer and dust removal.

Features:It overcomes the disadvantages of traditional towers such as easy scaling, blockage, low desulfurization efficiency, unstable operation, and high operating costs. At the same time, it reduces the liquid to gas ratio to 1-3L/m ³, and the operating costs are also relatively low.

11. Washing tower

scrubber

Introduction:Washing tower is a new type of gas purification treatment equipment. It is an improved version of the floating packing layer gas purifier and widely used in pre-treatment of industrial waste gas purification, dust removal, and other aspects, with excellent purification effects. For the coal gasification process, gas washing is inevitable, and this unit operation is used in any coal gasification technology. Due to its working principle being similar to the washing process, it is called a washing tower.

Features:

1) Water washing exhaust gas treatment system, cheap in price and simple in treatment method;

2) Vertical structure installed in economic space;

3) Suitable for gaseous and liquid pollution sources;

4) Dealing with a single source of pollution;

5) Suitable for medium and low air volume;

12. Fractionation tower

Fractionation tower

Principle:In a limited space, try to increase the heat exchange area of the liquid phase mixture as much as possible. Generally, the mixture used for distillation and fractionation is an organic azeotrope. The azeotrope is first heated and rises from the reaction kettle to the fractionation section, and the lower boiling point continues to rise. Because the temperature at the top of the tower is the same as that of the low boiling point substance after heat transfer, the low boiling point substance is fractionated, while the higher boiling point substance is cooled and refluxed to the reaction kettle or the lower half of the fractionation column. After the low boiling point substance is distilled, the higher boiling point substance is successively fractionated, followed by the distillation of the high boiling point substance, and finally the residue is at the bottom of the reaction kettle.