FAQ

Cooling tower classification introduction and cooling tower classification basis

Author：Trlon Views: Time:2021-06-16

　　Today, the closed-circuit cooling tower manufacturers bring you an introduction to the classification of cooling towers and the basis for the classification of cooling towers. As we all know, industrial machines and processes, as well as those dedicated to human comfort and generating large amounts of heat, must continue to emit heat if these machines and processes are to continue to increase their power. Although this heat is generally transferred to the cool water flow, the final heat is always transferred to the atmosphere, and it is always completed by some form of heat exchanger, which is generally completed by the cooling tower. Because of the natural process of transpiration, cooling towers are very effective heat transfer media, although their power is not high because of their limited surface area and their overall dependence on random wind.

　　1. Type classification of cooling tower

　　The design and manufacture of cooling towers have the following types:

　　1. Classified by mechanical ventilation method

　　(1) Forced ventilation

　　(2) Induction ventilation

　　(3) Mixed ventilation

　　2, according to the type of cooling tower airflow

　　(1) Countercurrent

　　(2) cross flow

　　(3) Shuangliu

　　(4) Single stream

　　3. Press the device method

　　(1) Field device

　　(2) Factory assembly

　　4, according to cooling tower shape classification

　　(1) square

　　(2) Circular mechanical ventilation (RMD)

　　2. Cooling tower information and introduction

　　1, mechanical ventilation

　　The mechanical ventilation tower uses electric fans (one or more) to make a large amount of air pass through the tower.

　　2, the difference between countercurrent and crossflow in mechanical ventilation cooling tower

　　Relative to the falling water, any type of air flow can be countercurrent or countercurrent. Cross flow means that the air flow in the filled part of the tower is horizontal, while counter flow means that the direction of the air flow is opposite to the direction of falling water.

　　Counter-flow tower occupies less floor space than cross-flow tower, but it is higher for a given capacity. The main advantage of the cross-flow tower is the pressure drop relative to its capacity, while the fan power requirement is lower, and then the energy cost is reduced.

　　The position of all mechanical towers must ensure that the discharged air is freely dispersed and will not be recirculated through the tower, so the air intake is not restricted. The cooling tower should be as close as possible to the refrigeration system it serves, but it should never be located below it, so that the condensed water is discharged from the system through the tray basin when the system is closed.

　　3. Structural features of forced ventilation cooling tower

　　As shown in the figure, the forced ventilation tower has electric fans, water basins and pipes in the tower structure. In this model, the fan sits on the base. An exterior wall without shutters. Instead, structural steel or timber frames are covered with panels made of aluminum, galvanized steel or asbestos cement boards.

　　During the operation, the electric fan forces the air horizontally through the packing at a low speed, and then vertically resists the downward water flow on both sides of the electric fan. The water trap located at the top of the tower removes water entrained in the air. Because the rotating equipment is built on a solid foundation, vibration and noise are minimized. Electric fans deal with the dry air first, and then greatly reduce the problems of corrosion and water condensation.

　　4, induced draft cooling tower

　　The diversion tower shown in the figure below has one or more electric fans on the top of the tower. These electric fans draw air upward to resist the downward movement of water around the wooden deck or filler. Because the airflow is opposite to the water flow, the coldest water at the bottom touches the driest air, and the warmest water at the top touches the humid air, which increases the heat transfer power.

　　5, mixed ventilation cooling tower

　　They are equipped with mechanical ventilation fans to add airflow. Therefore, they are also called fan-assisted natural ventilation towers. Their goal is to minimize the horsepower required for air activity, but this has the least impact on stacking costs. Properly dust-removing fans may only need to operate under conditions of high ambient temperature and peak load.

　　Three, the classification difference between counter-flow cooling tower and cross-flow cooling tower

　　1, countercurrent cooling tower

　　In the countercurrent tower, the air and the packing move vertically upwards, which is the opposite of the downward drop of water. Because of the need to extend the intake and exhaust chambers; use a high-pressure spray system; under normal circumstances, higher air pressure loss, some smaller counter-flow towers will be physically higher; more pump heads are required; and it is used than cross-flow similar products More fan power. However, in larger counterflow towers, the use of low-pressure gravity-related distribution systems, coupled with the use of large intake areas and pressurized spaces for air management, tends to balance or even reverse this situation. The closed nature of the countercurrent tower also limits the exposure of water to direct sunlight, which then hinders the growth of algae.

　　2, cross flow cooling tower

　　The 　　cross-flow tower has a packed structure, and air flows through a downward water flow in the horizontal direction. The water to be cooled is delivered to the hot water inlet pool located at the top of the water injection area, and is distributed to the water injection through the metering holes at the bottom of these pools by gravity.

　　Cross flow tower can be divided into:

　　Shuangliu:

　　In this type of tower, electric fans pass through two air intakes and through two rows of fillers to guide air.

　　Single stream:

　　This type of tower only needs one air inlet and one water injection port, and the remaining three sides are all installed in the shell. Single-flow towers are generally used in locations where the air passages that can only lead to the tower from one direction are not restricted.

　　This kind of tower has no heat transfer surface, and it only depends on the water consumption of the distribution system to promote the distribution of the most torrent to the air.

　　4. Introduction of cooling towers for on-site installations and cooling towers for factory installations

　　We can see two different types of cooling towers:

　　On-site erection

　　factory assembly

　　1. Erection of cooling tower on site:

　　The cooling towers installed on-site are those that carry out the primary construction activities at the final use site. All large towers, as well as many smaller towers, are prefabricated parts, parts stores, and shipped to the site. The cooling tower manufacturer generally provides the final assembly.

　　2, the factory installs the cooling tower:

　　The cooling tower assembled in the factory has actually undergone complete assembly during manufacture, and then shipped to the site as few parts as possible according to the transportation method.

　　Five, round cooling tower and square cooling tower type classification

　　There are two different types of cooling towers according to the shape:

　　1, square cooling tower:

　　These towers are constructed in a honeycomb method, linearly added to complete the length and number of cells required for special thermal performance.

　　2. Circular mechanical ventilation cooling tower:

　　As the name suggests, the tower is circular, but in fact it is circular in plan view, and the fans are gathered as close as possible to the center of the tower. Multifaceted towers, such as the octagonal mechanical draft (OMD), also belong to the general classification of "round" towers.

　　6. Open transpiration cooling tower classified by heat transfer method

　　All the cooling towers depicted here are transpiration towers, because they get the primary cooling effect from the transpiration that occurs when air and water are in direct contact. At the other end of the spectrum is the desiccant tower. In the desiccated tower, because the coil part of the desiccated surface is fully utilized, there is no direct contact between air and water (and no transpiration). Therefore, reasonable heat transfer will completely cool the water.

　　Between these extremes are plume reduction and water saving towers, during which more and more dull surface coils are introduced into the entire heat transfer system to alleviate specific problems or meet specific requirements.

Article Address：https://www.trlen.com/baike/443.html

Previous：Cooling tower motor installation method and use characteristics Next：The role and benefits of the use of float valves in closed cooling towers