How to select a closed cooling tower

How to choose a suitable and efficient closed cooling tower is a challenge for users. Today, Huatal Cooling will share with you the key value in the pressure loss of closed cooling towers: absolute roughness, hoping to help you.     Absolute roughness is a term in hydraulics. Due to the influence of processing conditions and operation, the solid wall of the pipeline is always more or less rough and uneven. The average height of the rough protrusion is called absolute roughness. Generally, cold-drawn tubes use f grade, Ra=3.2μm; cold-rolled tubes use e grade, Ra=1.6μm, and the allowable deviation is Ra+25%. In closed cooling towers, absolute roughness is mainly manifested in the following aspects:   1.Absolute roughness affects the wear resistance of the coil. The rougher the surface, the smaller the effective contact area between the mating surfaces, the greater the pressure, and the faster the wear.   2.Absolute roughness affects the stability of the mating properties, and the welding requirements between pipes and between the heat dissipation coil and the manifold are relatively high. For clearance fit, the rougher the surface, the easier it is to wear, causing the gap to gradually increase during the working process; for interference fit, the actual effective interference is reduced and the connection strength is reduced because the microscopic peaks are squeezed flat during assembly.   3.Absolute roughness affects the fatigue strength of the coil. There are large troughs on the surface of rough parts. Like sharp notches and cracks, they are very sensitive to stress concentration, thus affecting the fatigue strength of the parts.   4.Absolute roughness affects the corrosion resistance of the radiator. The rough surface makes it easy for corrosive gases or liquids to penetrate into the metal inner layer through the microscopic valleys on the surface, causing surface corrosion. 5. Absolute roughness affects the sealing of the entire closed cooling tower cooler. Rough surfaces cannot fit tightly together, and gases or liquids leak through the gaps between the contact surfaces.   General 304 stainless steel seamless steel pipes have hollow cross-sections and are widely used as pipes for conveying fluids. They are commonly used coils for closed cooling towers.   Jiangsu Huatal Cooling Technology Co., Ltd. focuses on the research and development, manufacturing and service of industrial cooling equipment. Its products include medium cooling, air cooling and hybrid combined cooling systems. With high-quality products and professional services, Huatal makes the cooling system more energy-saving, environmentally friendly, efficient, reliable, durable and convenient, and continuously creates the greatest value for customers.   For details, please refer to the "Closed Cooling Tower Selection Manual" compiled by Jiangsu Huatal Cooling Technology Co., Ltd.

Liquid level alarm device for closed cooling towers

The application scope of closed cooling towers is becoming more and more extensive, covering almost the entire industrial manufacturing field. Huatal Cooling shares with you the application of liquid level alarm devices, hoping to help you. Liquid level alarm refers to the alarm of water level through mechanical or magnetic induction methods, which can be used to control the start or stop of equipment such as water pumps at the same time with sound and light alarms or magnetic alarms. When the water level does not reach the set water level line, the circuit of power supply 1 is in an open circuit state, the electromagnet has no magnetism, and the contact block is connected to the contact above it under the action of the spring force. Circuit 2 is in an open circuit, and the indicator light and buzzer have no response; when the water level rises and rises to the set water level line, the circuit of power supply 1 is connected, and there is current in the circuit. At this time, the electromagnet generates magnetism, sucks down the contact block, and connects the circuit composed of power supply 2 on the right, the red light is on, and the buzzer sounds, notifying that the water is full, and stopping the water discharge through the feedback circuit. There are two ways to realize automatic liquid level alarm:   Method 1 is to control it through an electronic water level switch (BZ1201 or BZ2401) and a matching water level controller (BZ101, BZ102). The principle of the electronic water level switch is to detect the water level through an electronic probe, and then the water level detection dedicated chip processes the detected signal. When the measured liquid reaches the action point, it outputs a high or low level signal, and then cooperates with the water level controller to output a relay switch signal, or directly power the alarm to realize the liquid level alarm function. The electronic water level switch does not require a float and a reed switch, has no external mechanical action, is resistant to dirt and durable, is not afraid of floating objects, can be installed at any angle, and has a certain anti-wave function when installed vertically. This method is more practical, resistant to dirt, has a long life, and is safe. It has two alarm modes: ultra-low water level alarm and ultra-high water level alarm.   Method 2 is to use a float switch for water level alarm. This kind of float ball is made of plastic or stainless steel. The float ball with an annular magnet inside attracts the reed switch with a reed switch inside the rod to send out a switch alarm signal by floating up and down the water level at any time. It is resistant to high temperature, acid and alkali corrosion, and is widely used in water treatment, water cooling, machinery and equipment, and electronics industries. Now it has developed into flange installation, thread connection, cable float valve, stainless steel current float ball, plastic float ball, KEY plastic cable float ball, proximity switch, door magnetic switch, reed relay, etc.     The future liquid level alarm device can achieve the following advantages: 1.Two series circuits are connected through electromagnetic relays to ensure power safety; 2. In addition to the indicator light, a buzzer is also added as an alarm in the circuit to make the alarm signal more obvious; 3. Automatic water level control is achieved through the feedback circuit.   The application of liquid level alarm devices in closed cooling towers mainly focuses on two aspects: one is the liquid level monitoring of the internal circulation water, and the stability of the internal circulation water volume is achieved by monitoring the high or low water level of the buffer water tank; the second is the liquid level warning in the spray tank, which can effectively prevent the spray pump from running empty.

How to control scaling in closed cooling towers

During the operation of closed cooling towers, due to the existence of evaporation ratio, the concentration multiple of spray water directly affects the degree of scaling, and the concentration multiple is particularly important.     The concentration multiple refers to the ratio of the content of substances concentrated due to evaporation in circulating cooling water to the content of the same substance in make-up water, or the ratio of make-up water to sewage volume. The calculation method is as follows: The ratio of the salt content of circulating cooling water to make-up water is called the concentration ratio. This indicator is generally calculated based on the ratio of the chloride ion (or potassium ion) content in circulating water and make-up water. The salt content of fresh water is different from that of circulating water after the concentration process. The ratio N between the two is called the concentration multiple and is expressed as follows: N =SCirc / SMake Where SCirc --- the salt content of circulating water, mg/L; SMake --- the salt content of fresh water, mg/L;   It is troublesome to calculate the concentration multiple based on the salt content. In practice, it is often necessary to select a certain ion concentration or conductivity in the circulating water that is not easy to consume but can be quickly measured to replace the salt content for the calculation of the concentration multiple. Generally, the concentration multiple is calculated based on the CL- concentration. However, if liquid chlorine is used as a biocide in the circulating water and CL- is introduced, it is not appropriate to calculate the concentration multiple based on CL-. Therefore, SiO2, K+, etc. are usually used to calculate the concentration multiple. The ratio of the example concentration in the circulating water to the corresponding ion in the make-up water. Intuitively speaking, it is the ratio of the circulating water to the make-up water. It is a standard for measuring water quality. It is widely used in circulating water such as industrial cooling water.   Increasing the concentration multiple of circulating cooling water can reduce the amount of make-up water, thereby saving water resources; it can also reduce the amount of sewage discharged, thereby reducing environmental pollution and the amount of wastewater treatment. In addition, increasing the concentration multiple can also save the consumption of water treatment agents, thereby reducing the cost of cooling water treatment. However, increasing the concentration multiple too much will increase the hardness, alkalinity and turbidity in the circulating cooling water too much, and the scaling tendency of the water will increase a lot, making scaling control too difficult. It will also increase the content of corrosive ions (such as Cl and SO4) and corrosive substances (such as H2S, SO2 and NH3) in the circulating cooling water, and the corrosiveness of the water will increase, making corrosion control more difficult; increasing the concentration multiple too much will also increase the residence time of the reagent (such as polyphosphate) in the cooling water system and hydrolyze. Therefore, the higher the concentration multiple of cooling water, the better. Generally, the thermal power system can be controlled at 5 to 8 times, and the chemical industry and oil refining can be controlled at 2 to 4 times.   Generally, we increase the concentration multiple of cooling water by controlling the evaporation amount. The benefits are: increasing the concentration multiple of cooling water can reduce the amount of supplementary water and save water resources; increasing the concentration multiple of cooling water can reduce the amount of sewage discharged, thereby reducing environmental pollution and wastewater treatment; increasing the concentration multiple of cooling water can save the consumption of water treatment agents, thereby reducing the cost of cooling water treatment;   Excessively increasing the concentration multiple of cooling water also has the following disadvantages: excessively increasing the concentration multiple of cooling water will make the hardness and alkalinity of cooling water too high, and the scaling tendency of water will increase;   Therefore, if we want to ensure the treatment effect of cooling water, we must control the concentration multiple of cooling water. Usually, the concentration multiple of closed cooling tower spray circulation cooling water is generally controlled at 4 to 5.

How to design spray water for closed cooling towers

The closed cooling tower includes integrated devices such as the spray system, exhaust system, and cooling system. How to make each component most efficient should be determined through various experimental measured data and calculations.   The working principle of the closed cooling tower is to circulate the working fluid (pure water or other liquid) in the coil of the closed cooling tower, and the heat of the working fluid is dissipated through the coil into the spray water flowing through the outer surface of the coil. At the same time, the air outside the unit enters from the air inlet grille on the chassis, opposite to the flow direction of the water, and flows upward through the coil. A small part of the water evaporates and absorbs heat, and the hot and humid air is discharged into the atmosphere by the ventilator at the top of the cooling tower. The rest of the spray water falls into the bottom water tray, which is recirculated by the spray pump to the water distribution system and then back to the coil.     The spray system of the cooling tower is an important component of the closed cooling tower. At present, the spray system mostly adopts the method of connecting the spray straight pipe with the water inlet. The spray system has the problems of large spray water flow at the front end, small spray water flow at the rear end, uneven water spray, and poor cooling effect.   To achieve the above-mentioned purpose, the utility model provides a new type of composite flow cooling tower spray system, including a water inlet and a spray pipeline, characterized in that the spray pipeline includes a spray straight pipe, a first spray circuit and a second spray circuit, and the rear end of the spray straight pipe, the first spray circuit and the second spray circuit are connected by a combination of a four-way pipe fitting and a three-way pipe fitting, and the water inlet, the front end of the spray straight pipe, the first spray circuit and the second spray circuit are connected by two groups of four-way pipe fittings.     Among them, the corners of the first spray circuit and the second spray circuit are connected by a 90° elbow.   Among them, the spray straight pipe, the first spray circuit and the second spray circuit are evenly provided with nozzles.   Compared with the prior art, the utility model has the following beneficial effects:   The novel composite flow cooling tower spray system adopts a double loop design, the spray water flow is diverted by the front four-way pipe fitting to flow backward, and the water flows to the rear end through the rear three-way pipe fitting in the reverse direction, so that the pressure drop of the water flow at the rear end is not too large, so that the front and rear water flow of the entire spray system is uniform.   As shown in Figure 1-2, a novel composite flow cooling tower spray system includes a water inlet 1 and a spray pipeline, wherein the spray pipeline includes a spray straight pipe 2, a first spray circuit 3 and a second spray circuit 4, and the rear end of the spray straight pipe 2, the first spray circuit 3 and the second spray circuit 4 are connected by a combination of a four-way pipe fitting 5 and a three-way pipe fitting 6, and the water inlet 1, the front end of the spray straight pipe 2, the first spray circuit 3 and the second spray circuit 4 are connected by two sets of four-way pipe fittings 5.   Among them, the corners of the first spray circuit 3 and the second spray circuit 4 are both connected by 90° elbows. Spray heads are evenly arranged on the spray straight pipe 2, the first spray loop 3 and the second spray loop 4.   When the spray system of the cooling tower is working, the spray water flow is diverted by the front four-way pipe fitting 5 to flow backward, and the water flows to the rear end through the rear three-way pipe fitting 6 in the reverse direction, so that the water flow pressure at the rear end does not drop too much, so that the front and rear water flow of the entire spray system is uniform.    

How to control scaling in closed cooling towers

During the operation of closed cooling towers, due to the existence of evaporation ratio, the concentration multiple of spray water directly affects the degree of scaling, and the concentration multiple is particularly important.     The concentration multiple refers to the ratio of the content of substances concentrated due to evaporation in circulating cooling water to the content of the same substance in make-up water, or the ratio of make-up water to sewage volume. The calculation method is as follows: The ratio of the salt content of circulating cooling water to make-up water is called the concentration ratio. This indicator is generally calculated based on the ratio of the chloride ion (or potassium ion) content in circulating water and make-up water. The salt content of fresh water is different from that of circulating water after the concentration process. The ratio N between the two is called the concentration multiple and is expressed as follows: N =SCirc / SMake Where SCirc --- the salt content of circulating water, mg/L; SMake --- the salt content of fresh water, mg/L;   It is troublesome to calculate the concentration multiple based on the salt content. In practice, it is often necessary to select a certain ion concentration or conductivity in the circulating water that is not easy to consume but can be quickly measured to replace the salt content for the calculation of the concentration multiple. Generally, the concentration multiple is calculated based on the CL- concentration. However, if liquid chlorine is used as a biocide in the circulating water and CL- is introduced, it is not appropriate to calculate the concentration multiple based on CL-. Therefore, SiO2, K+, etc. are usually used to calculate the concentration multiple. The ratio of the example concentration in the circulating water to the corresponding ion in the make-up water. Intuitively speaking, it is the ratio of the circulating water to the make-up water. It is a standard for measuring water quality. It is widely used in circulating water such as industrial cooling water.   Increasing the concentration multiple of circulating cooling water can reduce the amount of make-up water, thereby saving water resources; it can also reduce the amount of sewage discharged, thereby reducing environmental pollution and the amount of wastewater treatment. In addition, increasing the concentration multiple can also save the consumption of water treatment agents, thereby reducing the cost of cooling water treatment. However, increasing the concentration multiple too much will increase the hardness, alkalinity and turbidity in the circulating cooling water too much, and the scaling tendency of the water will increase a lot, making scaling control too difficult. It will also increase the content of corrosive ions (such as Cl and SO4) and corrosive substances (such as H2S, SO2 and NH3) in the circulating cooling water, and the corrosiveness of the water will increase, making corrosion control more difficult; increasing the concentration multiple too much will also increase the residence time of the reagent (such as polyphosphate) in the cooling water system and hydrolyze. Therefore, the higher the concentration multiple of cooling water, the better. Generally, the thermal power system can be controlled at 5 to 8 times, and the chemical industry and oil refining can be controlled at 2 to 4 times.   Generally, we increase the concentration multiple of cooling water by controlling the evaporation amount. The benefits are: increasing the concentration multiple of cooling water can reduce the amount of supplementary water and save water resources; increasing the concentration multiple of cooling water can reduce the amount of sewage discharged, thereby reducing environmental pollution and wastewater treatment; increasing the concentration multiple of cooling water can save the consumption of water treatment agents, thereby reducing the cost of cooling water treatment;   Excessively increasing the concentration multiple of cooling water also has the following disadvantages: excessively increasing the concentration multiple of cooling water will make the hardness and alkalinity of cooling water too high, and the scaling tendency of water will increase;   Therefore, if we want to ensure the treatment effect of cooling water, we must control the concentration multiple of cooling water. Usually, the concentration multiple of closed cooling tower spray circulation cooling water is generally controlled at 4 to 5.

ELB cooling closed cooling tower

As closed cooling towers are increasingly used in industrial water cooling, the number of industries served by closed cooling towers is also gradually increasing. The process of ELB deep hole processing has a long history. With the development of technology, ELB has become an effective method and tool for processing precision deep holes. It is widely used in deep hole processing in various industries such as automobiles, molds, hydraulics, aerospace, textile machinery, heat exchangers and machine tool manufacturing.     ELB is a single-edge internal cooling and external chip removal deep hole drill for processing deep holes (aspect ratio>5) and precision shallow holes. It is mainly used for processing deep holes of φ0.9~φ50mm. The drilling depth can reach 250 times the diameter of the processed hole. The dimensional accuracy of the hole can reach IT7, the surface roughness value Ra can reach 0.1~0.8μm, the roundness is <5μm, and the straightness can reach 0.4/1 000. The gun drill consists of three parts: drill bit, drill rod and drill handle. The drill bit is a hollow structure. High-pressure cooling oil flows in from the center hole at the rear of the drill shank. Under the action of high pressure, the drill chips are discharged from the workpiece along the V-shaped groove, taking away the cutting heat, while reducing the friction loss between the tool and the workpiece, and improving the drilling accuracy. The drill shank is designed according to the professional standards of the gun drill manufacturer. The three major elements of the gun drilling process are equipment, tool (ELB) and cooling and lubrication device. Among them, whether the cooling and lubrication device can supply sufficient and clean cutting fluid has an important impact on the life of the tool, the surface roughness of the hole and the dimensional accuracy. Cooling and lubrication mainly have the following functions: ① Reduce the wear of the tool and the guide sleeve. ② Inhibit the formation of built-up edge. ③ Cool the tool to reduce and eliminate friction heat and cutting heat. ③ Under the action of pressure, friction and temperature, a thin oil film is formed to prevent the tool and the workpiece from biting. ④ Continuously remove chips.   The cooling and lubrication device must have the following functions:   (1) Purification function. During the gun drilling process, a large amount of chips are mixed into the cooling and lubricating fluid, and the drill chips and oil need to be separated and purified before they can be recycled. Relevant tests show that when the cutting fluid filtration accuracy is 20μm, the tool can drill 100 holes between two sharpenings, and when the filtration accuracy is 10μm, other conditions remain unchanged, then 500 holes can be drilled between two sharpenings. The same is true for the relationship with the surface quality of the machining. When the cutting fluid filtration accuracy is controlled at about 50μm, the surface roughness of the machining is 5μm, and when the filtration accuracy is controlled at 10μm, the surface roughness of the machining is 0.5~1μm. Therefore, the cleanliness of the cutting fluid is closely related to the surface quality of the machining and the tool life.   (2) Pressure and flow of cutting fluid. During the gun drilling process, a cooling lubricant with a certain pressure and flow must be provided. If the flow and pressure are insufficient, the generation of chip tumors cannot be suppressed, and the chips cannot be removed cleanly, which directly affects the machining quality, tool life and equipment safety. The pressure and flow setting of the cutting fluid is mainly related to the size and depth of the machining hole. The relationship is shown in Figure 2. In Figure 2, the pressure is determined by the hole diameter and hole depth. For the same hole diameter, the deeper the hole, the greater the pressure. The flow rate is related to the ELB center oil diameter and the oil pump output characteristics, and no adjustment is required during processing. During processing, the set pressure can be appropriately adjusted according to different processing effects.     (3) Oil temperature control. During ELB processing, a large amount of heat is generated due to the deformation of metal chips, the friction between the drill support pad and the workpiece hole pad, and the friction of chips on the rake surface of the tool, and the radiated heat is relatively poor. According to relevant information, when the hole diameter is less than 20mm, the heat generated is 17×106J/h, and when drilling a φ40mm hole diameter, the heat generated is 46×106J/h. Only 3.75% of this heat is radiated through the workpiece, and 96.25% of the heat is cooled by the cutting fluid. Therefore, the temperature of the cutting fluid rises very quickly and must be controlled. Generally, the temperature should be controlled between 20 and 45°C, and the maximum should not exceed 50°C. When it exceeds 50°C, not only can the tool not be in a good cooling state for cutting, but the properties of the cutting fluid will also deteriorate, thus affecting the lubrication effect. When the temperature is below 20°C, the low temperature will encounter the high temperature cutting zone, which will easily lead to the formation of small pieces of foam on the tool surface, causing the tool cutting to be damaged and causing adverse consequences. Therefore, the volume of the cutting fluid tank should not only have sufficient volume, but also need to be equipped with a temperature control device to maintain good cutting performance.   (4) Protection device. During the gun drilling process, due to tool wear, increased chip removal resistance and changes in working conditions, the pressure of the cutting fluid will also fluctuate to a certain extent. In order to prevent pressure fluctuations from affecting normal cutting processing, the cutting fluid pressure must be monitored throughout the deep hole drilling process. When the pressure exceeds or falls below the set range, the machine tool can automatically retract the tool or take corresponding protective measures to ensure the safety of the workpiece, tool and equipment.   There are generally two ways to cool the ELB oil cooling cycle in a closed cooling tower. One is to directly output the oil into the closed cooling tower for cooling. This method has a faster heat exchange efficiency, but if there are many ELBs, problems such as pipeline leakage will cause lubricating oil leakage, resulting in large losses and uncontrollable risks. The other method is to use a heat exchanger for indirect heat exchange. The closed cooling water system is at the other end, providing cooling water below 32°C to circulate in the system.