1. Overview Tubular cooler is a heat exchange device commonly used in metallurgy, chemical industry, energy, transportation, light industry, food and other industrial sectors. It is suitable for different working conditions such as cooler, condensation, heating, evaporation, and waste heat recovery. Due to its sturdy structure, great flexibility in use, and strong adaptability, a lot of improvements have been made to the structure, technology and materials in recent years, making its technical performance more reasonable and advanced. Therefore, in many types of heat exchangers, coolers and tube heat exchangers still occupy an important position.

2. Structure and working principle

The tube-and-tube cooler consists of two parts: an outer shell and an inner cooler body. Due to the different specific structure, the external connection form is divided into pipe thread type and flange type; from the installation form, it is divided into horizontal and vertical; from the floating form, it is divided into floating disc type and floating head type; from the cooler tube structure Divided into solenoid type and finned tube type; from the structure of the baffle, it can be divided into arch baffle, rectangular baffle, double weir baffle and circular baffle, etc., all according to specific conditions Optional.

The outer shell includes: a cylinder, a water diversion cover and a return water cover. It is equipped with oil inlet and outlet pipes and water inlet and outlet pipes, to understand the rules of Baccarat, and is equipped with oil, drain, exhaust screw plugs, zinc rod mounting holes and thermometer interfaces, etc.

The cooler body is composed of a cooler tube, a fixed orifice plate, a movable orifice plate, a baffle, etc. The two ends of the cooler pipe are connected with the fixed and moving orifice plates, and the oil leaks from the inside of the cooler of the cooler loader; the fixed orifice plate is connected with the outer body flange, and the moving orifice plate can be freely expanded and contracted in the outer body to eliminate the temperature effect on the cooler pipe. The effect of thermal expansion and contraction. The baffle has the function of enhancing heat transfer and supporting the cooler tube.

The heat medium of the tube-and-tube cooler flows from the inlet of the tube to the outlet of the tube through the baffle channels in sequence. The cooler medium adopts double-pipe flow, that is, the cooler medium enters one half of the cooler pipe from the water inlet through the water distribution cover, and then flows from the return water cover into the other half of the cooler pipe into the other side water distribution cover and outlet pipe. . In the process of double-pipe-pass flow of the cold medium, the waste heat released by the absorbing heat medium is discharged from the water outlet, so that the working medium maintains the rated working temperature.

Three, use and operation

1. The foundation of the cooler must be sufficient to prevent the cooler from sinking. Enough space should be left at the end of the fixed-hole pan head so that the tube bundle can be drawn out of the shell. After aligning, tighten the anchor screws and connect the inlet and outlet pipes of the cold and hot media.

2. Before starting the cooler, the air in the cavity should be exhausted to improve the heat transfer efficiency. The steps are:

(1) Loosen the vent plugs on the hot and cold medium ends, and close the medium discharge valve;

(2) Slowly open the water inlet valve of the hot and cold medium until the hot and cold medium overflows from the vent hole, then tighten the vent screw plug and close the water inlet valve.

3. When the water temperature rises by 5～10℃, open the water inlet valve of the cooler medium (Note: Do not open the water inlet valve quickly, because a large amount of cooler water flows through the cooler, which will make the surface of the heat exchanger long-term A layer of “super-cooling layer” with poor thermal conductivity is formed), and then open the inlet and outlet valve of the heating medium to make it in a flowing state, and then pay attention to adjusting the flow rate of the cooler medium to keep the heating medium at the best use temperature.

4. If galvanic corrosion occurs on the water side of the cooler, a zinc rod can be installed at the designated position.

5. Before the dirty medium passes through the cooler, there should be a filter device.

6. The pressure of the medium in the cooler should be greater than the pressure of the medium in the cooler.

Four, maintenance and repair

1. After long-term work, the surface of the cooler tube will be fouled, which will increase the thermal resistance and flow resistance, which will gradually reduce the heat exchange performance, so that the requirements of the cooler cannot be guaranteed. Obviously, the focus of maintenance should be on dirt cleaning, here are several cleaning methods:

（1）

a. Use electric pigging tools. That is, a flexible shaft is driven by a motor to rotate, and the shaft end is covered with a nylon brush or a steel wire brush for rotating scrubbing. The working principle and instructions of the cooler tube cooler, and the water is injected into the shaft through a leak-proof cover. Around in order to wash out loose dirt in time.

b. Use a round tube, weld a wire brush with the same inner diameter as the tube at one end and push it while rotating. Dirt can accumulate in the inner cavity of the tube, and it will not produce dirt. The thicker it accumulates, the more difficult it is to advance. This method is more common. Use, but the labor intensity is high, the oil is leaking from the cooler of the cooler loader.

(2) Use high-pressure pump (pressure 10-20Mpa) to spray high-pressure water for flushing, the effect is better, and it is mainly used for cleaning between pipes.

(3) The sponge ball is used to automatically clean the inside of the heat exchange tube. According to different scales, sponge balls of different hardness are used. For special hard scales, a "band"-shaped emery sponge ball can be used. Its function is to use a relatively soft and elastic sponge ball to enter the heat exchange tube. When the sponge ball is compressed, it is in contact with the inner wall of the tube. The ball and the tube wall move relative to each other, constantly rubbing the tube wall to remove the deposits.

(4) Chemical cleaning method:

a. The oil side cleaning can be reversed cycle cleaning with trichloroethylene solution, and the solution pressure is not greater than the rated working pressure. The cleaning time depends on the dirt. The cooler circulates cooling water, and then clean water is introduced into the device for cleaning until the water flowing out is clean.

b. Adopt soaking carbon tetrachloride. Pour the solution into the cooler and watch the color of the solution after 15-20 minutes. If the mixed corrosion is unacceptable, replace with a new solution and re-soak until the outflow solution is similar to the clean color, and then rinse with water repeatedly. This cleaning should be done Good ventilation environment to avoid poisoning. This method is suitable for oil cleaning.

2. The failure of the cooler is mostly caused by the cooler tube. The pipe wall is thinned and perforated due to corrosion, cavitation and abrasion, and the joints and other damages are caused by thermal expansion and contraction, and vibration caused by fluid movement. After the cooler tube is damaged, the two media will permeate each other and should be repaired in time. The methods are as follows:

(1) Find out the damaged cooler tube and plug both ends with a tube plug. The taper of the pipe plug is between 3 and 5 degrees, the hardness of the pipe plug material should be lower than or equal to the hardness of the pipe, and the total number of blocked pipes should not exceed 10% of the total.

(2) Take out the damaged tube, replace it with a new tube and re-expand it.

(3) If there is leakage at the junction of the pipe end and the tube sheet, the joint should be re-expanded. If the corrosion is severe, the tube bundle should be replaced.

3. The cooler that is out of service in winter should drain the medium in the cavity to prevent freezing and cracking of the cooler.

4. The disassembly and reassembly of the cooler should be carried out according to the following steps:

(1) Close the oil and water inlet and outlet valves, release the stagnant medium, and then remove the cooler from the system.

(2) Remove the return water cover and the water distribution cover, check the seal ring, the cooler tube damage and fouling, etc. If you only plug the pipe or replace the cooler tube, you can proceed immediately. If you need to pull out the cooler tube bundle, it must be removed from the fixed tube plate (large cooler can be vertical (fixed tube plate facing down)), and then use lifting equipment The tube bundle can be exposed by lifting the shell.

(3) When assembling, follow the reverse process of disassembly. Generally, the sealing ring should be replaced with a new one.

(4) After installation, the air tightness test on the oil side and then on the water side should be carried out separately, and the test pressure should be greater than 1.2 times the actual working pressure.