Ordinary Vacuum Freeze Dryer，Cold Drying Machine Suction Dryer

Ordinary Vacuum Freeze Dryer，Cold Drying Machine Suction Dryer

Cold drying machine is short for refrigerated drying machine. Cold drying machine is a new technology and belongs to the air source processing element in the pneumatic system.

The working principle

The temperature of compressed air is reduced to dew point temperature range of 2~10℃ by heat exchange between refrigerant and compressed air. With the continuous development of the cold drying machine industry, more and more enterprises enter the air compressor industry, more and more people favor the cold drying machine industry, and many enterprises stand out,

According to the cooling mode of condenser, the cold drying machine is divided into two types: air-cooled type and water-cooled type;

According to the high and low inlet temperature, there are high temperature inlet type (below 80℃) and normal temperature inlet type (about 45℃);

According to the working pressure is divided into ordinary type (0.3-1.0mpa) and medium and high pressure type (1.2mpa above).

In addition, many special specifications of cold drying machine can be used to deal with non-air media, such as carbon dioxide, hydrogen, natural gas, blast furnace gas, nitrogen and so on.

Selection of parameters：

The technical parameters of the cold drying machine are mainly: processing capacity (Nm3/min), intake temperature (℃), working pressure (MPa), pressure drop (MPa).

The target parameter of cold drying machine, "pressure dew point" (℃), is generally not marked on the "performance specification sheet" as an independent parameter in the product catalog of foreign manufacturers. The reason is that the "pressure dew point" is related to many parameters of the compressed air being processed. If "pressure dew point" is indicated, the relevant conditions (such as intake temperature, operating pressure, ambient temperature, etc.) should also be included.

Cold Drying Machine Suction Dryer  The four parts

The refrigeration compressor is the heart of the refrigeration system and is finally discharged by the exhaust pipe

The function of condenser is to cool the high-pressure and superheated refrigerant vapor discharged from the refrigerant compressor into liquid refrigerant, and its heat is taken away by cooling water or cooling air. So that the refrigeration process can be continuous.

The evaporator is the main heat exchange component of the cold and dry machine. The compressed air is forced to cool in the evaporator, and most of the water vapor is cooled and condensed into liquid water and discharged out of the machine, so that the compressed air can be dried. Low pressure refrigerant liquid, in the evaporator phase change into low pressure refrigerant steam, in the process of phase change to absorb heat around, so as to cool the compressed air.

Expansion valve

Thermal expansion valve (capillary) is the throttling mechanism of refrigeration system. In the cold drying machine, the supply of evaporator refrigerant and its regulator are realized by throttling mechanism. Throttling mechanism enables refrigeration from high temperature and pressure liquid into the evaporator.

Fluorine handling leakage

The most intuitive surface phase is the refrigerant pressure gauge is zero. The leakage of fluorine must first find the leakage point, leakage point needs patience, careful and certain methods. Specifically, this is the first visual inspection method, open the machine box plate to observe the inside of the machine, because the refrigerant in operation, there will be compressor lubricating oil mixed in it, if the Freon leak will bring the lubricating oil out, then carefully observe the inside of the machine, if there is a flake of oil belt, it is likely to be the leak point. Then it is to check the inside of the machine capillary copper pipe, that is, those thin copper pipe and process pipe below 6 mm, there is no broken phenomenon. After passing the above basic checks, make a mark of any suspected areas. Then it is necessary to confirm the leak point by adding inert gas at a certain pressure. If conditions are available, it is best to use nitrogen to maintain pressure, no nitrogen with gaseous freon can also be used, it is strictly prohibited to use oxygen to maintain pressure leakage, that is looking for death.

Cold Drying Machine Suction Dryer

start should be slow to join gas pressure, pressure and observe the person of the refrigerant pressure (small cubic only refrigerant low pressure table, two more than 15 cubic have high and low pressure refrigerant table), the pressure to 0.2 Mpa (2.0 KGF) temporarily stop, and then listen carefully to the voice within the machine ever leak, if there are available according to the voice of the funnelled. If not, continue to apply pressure to 0.4-0.5mpa. At this time, find a sponge dipped in soapy water, in the place where there is doubt, check first, and then check all the connecting pipes (copper nuts) inside the machine. If there is a leak, a bubble will blow out, and this process needs to be very careful. If the leakage point is not found through the above methods, then unfortunately, it is likely to be the evaporator internal leakage. Evaporator internal leakage is more troublesome to deal with. First of all, it must be confirmed. It can be confirmed by disconnecting the evaporator and refrigeration system and then holding the pressure separately. If the pressure is found to be reduced after holding the pressure separately, it can be determined. There is also a relatively simple way to open the inlet of compressed air. If the pressure of the refrigerant pressure gauge rises after a period of time, it can also be sure that the refrigeration system is communicated with the air system, because their only exchange part is the evaporator. Therefore, the evaporator internal leakage can also be determined.

After checking the leakage point is the leakage, according to the different leakage point, for the bell loose leakage point, just use the plate hand to do the corresponding fastening, if it is the leakage point of copper pipe welding type, you need to use brazing. Brazing leakage is one of the most commonly used skills in the refrigeration repair industry. The so-called brazing is to use oxygen and acetylene flame to heat the low silver electrode and the required repair welding parts, so that the electrode and repair welding parts are fused together and the leakage point is blocked. Brazing should be the first refrigeration system pressure discharge zero, and then use the brazing gun first open acetylene, lit after the appropriate addition of oxygen, slowly adjust the proportion of oxygen and acetylene gas, so that the flame into a neutral flame - oxide flame, and then heating the required welding parts and silver electrode so that both dissolved together. The specific method needs to be mastered by the operator through certain training. After the leakage point is treated, the pressure of the system needs to be maintained again to confirm whether the leakage repair welding is successful.

After the completion of the leak, the need to vacuumize the system, and then add the specified quality of liquid freon (the specific number of reference to the basic configuration table), add refrigerant should be specially left from the cold dryer liquid needle valve to join. For larger machines, fluoride should be added to the high-pressure charging port first. If the prescribed dose cannot be added at one time, it should be slowly added to the prescribed dose from the low-pressure port after starting the machine.

Use attention

1) Do not put in the sun, rain, wind or relative humidity greater than 85% of the place. Do not place in an environment with dust, corrosive or flammable gases. Do not place in a place where there is a danger of vibration and condensation water freezing. Do not be too close to the wall to avoid poor ventilation. Must be used in the environment with corrosive gases, should choose copper pipe by rust treatment dryer or stainless steel heat exchanger type dryer. It should be used at ambient temperature below 40℃.

2) The inlet of compressed air should not be connected wrong. To facilitate maintenance, a bypass pipeline should be installed to ensure maintenance space. The vibration of the air compressor should be prevented from being transmitted to the dryer. Pipe weight should not be added directly to the dryer.

3) The drain pipe should not stand up, and should not be broken or flattened.

4) The power supply voltage is allowed to fluctuate less than ±10%. Leakage circuit breaker with appropriate capacity should be set. Must be grounded before use.

5) The inlet temperature of compressed air is too high, the ambient temperature is too high (above 40 ° C), the use of flow exceeds the rated air volume, the voltage fluctuation exceeds ±10%, the ventilation is too poor (winter should also be ventilated, otherwise the room temperature will rise), the protection circuit will play a role, the indicator light is off, stop running.

6) When the air pressure is higher than 0.15mpa, the outlet of the normally open automatic drainer can only be closed. When the displacement of the cold dryer is too small, the drain is in the open state and air is blown out.

7) The quality of compressed air is poor, such as mixed with dust and oil, these stolen goods will adhere to the heat exchanger, reduce its work efficiency, and drainage is also easy to fail. You want to set the filter at the inlet of the dryer, and make sure that the drainage is not less than once a day.

8) The air vent of the dryer should be vacuumed once a month.

9) Switch on the power supply, and then switch on the compressed air after the running state is stable. After stopping operation, it must wait more than 3 minutes before starting again.

10) If the automatic drainer is used, it should be checked regularly whether its drainage function is normal. Always clean the dust on the condenser. To often check the refrigerant pressure, can judge whether the refrigerant leakage and the ability of the freezer is changed. Check whether the temperature at which condensate is excluded is normal

Maintenance:

(1) Observe and record the instrument value 4 times in each shift

1. The pressure difference between inlet and outlet of compressed air shall not exceed 0.035mpa;

2, evaporation pressure gauge 0.4MPA-0.5mpa;

3, high pressure gauge 1.2MPA-1.6mpa

(2) Observe the drainage and sewage system regularly

1. Clean the floating ball drainer once a week or so

2. The sewage pipe is discharged once a week

Cleaning method of electronic drainer:

A. Close the ball valve in front of the automatic drainer;

B. Loosen the fixing nut on the upper end and take out the timing coil. During the cleaning process, the coil must not touch the water; otherwise, the coil will burn off.

C. Remove the hose and loosen the drainer body to empty the compressed air in the drainer;

D. Remove the spool and wipe it clean;

E. Screw the valve body back to its original position. Open the front ball valve slightly and empty the impurities, water and oil in the drainage system with compressed air; Wipe the valve body with a cloth;

F. Reinstall the spool and timing coil according to the original position; Reinstall the hose and open the front ball valve

(3) Often observe the inlet temperature of cooling water system and compressed air system

1.cooling water temperature 2~32℃;

2.water pressure 0.15~ 0.3mpa;

3. The inlet temperature of compressed air should generally be less than or equal to 45℃(if the inlet pipe is not hot by hand), except for special exceptions

4. The cooling water should be kept clean and the Y-type filter should be cleaned once a half month and the water quality is good once a month; The water condenser is cleaned once a year (depending on the water quality) and the air condenser is cleaned once a month.

◆ Air condenser cleaning should avoid pressure cold condenser wing surface

There should be enough space around the air condenser for ventilation and heat dissipation. It cannot work under direct sunlight. Regular use of compressed air to remove surface ash cleaning with compressed air flow, pressure should not be too large

◆ Shell and tube type water condenser cleaning: close the inlet and outlet of cooling water open the end cover of the water pipe and the outer cover of the gasket only need to be cleaned with water; Copper pipe with gas, water or connected with a rag stick cleaning; When cleaning, we should pay attention not to use too much force to avoid breaking the internal copper pipe

(4) often observe the refrigeration system

1. The compressor is normally cold and frosty when touched by hand at least once a day;

2, dry filter every week by hand to touch the temperature difference between the two sides should not be very large (import heat, export cool need to be replaced);

3. If the compressor is found to have abnormal sound and heat, contact the after-sales service as soon as possible

(5) Check the electrical control system: clean the dust and tighten the wiring end (it must be carried out without electricity)

(6) Appearance maintenance

Regularly wipe the oil and dust on the surface of the equipment with a clean towel. Install the dust and oil on the ground of the cold dryer and air compressor to keep the environment clean