working principle of natural gas compressor maintenance and repair of natural gas compressor   Working principle of natural gas compressor When the compressor is running, the motor drives the crankshaft to rotate, and the piston moves back and forth through the connecting rod. When the crankshaft rotates for one cycle, the piston moves back and forth once, and the process of suction, compression and exhaust is realized successively in the cylinder, that is, a working cycle is completed. (1) During the suction process, when the piston moves to the left, the working volume in the cylinder gradually increases and the pressure gradually decreases. When the pressure drops slightly below the pressure in the intake pipe, the gas in the intake pipe will push open the suction valve and enter the cylinder until the piston reaches the leftmost position (also known as the inner dead center), the working volume is the maximum and the suction valve begins to close. (2) During compression, when the piston moves to the right, the working volume in the cylinder decreases and the gas pressure increases gradually. Because the suction valve has a check function, the gas in the cylinder cannot flow back to the intake pipe. At the same time, because the gas pressure in the exhaust pipe is higher than that in the cylinder, the gas in the cylinder cannot flow out of the exhaust valve, and the gas in the exhaust pipe cannot enter the cylinder due to the check effect of the exhaust valve. At this time, the amount of gas in the cylinder remains constant, and the gas pressure increases with the right movement of the piston. (3) During the exhaust process, when the piston moves to a certain position to the right, the gas pressure in the cylinder rises to slightly higher than the gas pressure in the exhaust pipe, and the gas will push open the exhaust valve and enter the exhaust pipe until the piston moves to the rightmost position (also known as the outer dead center). When the exhaust valve is closed, the piston moves left again, and the above process repeats.   Difference between natural gas compressor and ordinary compressor Natural gas compressor is different from ordinary compressor. Natural gas compressor mainly compresses natural gas (including content, methane, propane, etc.) with high pressure and high risk level. Ordinary compressor mainly compresses air, which is very single to medium and low pressure. Compressed natural gas has the same composition as pipeline natural gas, The main component is methane (CH4). CNG can be used as vehicle fuel. LNG (liquefied natural gas) can be used to make CNG. This CNG fueled vehicle is called NGV (natural gas vehicle). Liquefied petroleum gas (LPG) is often confused with LNG. In fact, they are obviously different. The main component of LPG is propane (more than 95%), there is also a small amount of butane. LPG is stored in liquid tank container under appropriate pressure and is used as civil fuel and vehicle fuel. Main...

Current situation of natural gas compressor industry The domestic natural gas compressor industry started relatively late and began to explore the new market of natural gas compressor at the end of last century. Natural gas compressor belongs to high-pressure ratio large industrial centrifugal compressor, while Shengu group occupies most of the domestic market share in the field of centrifugal compressor and basically monopolizes in the field of high-end technology, The annual total value of the domestic compressor market is less than 10 billion yuan, belonging to a small industry. The centrifugal compressor is a high-grade industrial customized product. Shangu group was the first three-line factory dispatched by Shengu group to support the construction. The two sides have made clear the main direction. Shangu group mainly focuses on axial compressors and occupies most of the domestic market share. Around 2015, due to the domestic adjustment of supply and demand structure, The axial flow machine market has shrunk seriously. Shangu group has vigorously developed the field of centrifuges and began to participate in the market competition of long-distance pipeline compressors. In the natural gas compressor industry, it is called long-distance pipeline compressor. It is a centrifuge with relatively standard design specifications, and the model needs to be fixed. It was first driven by PetroChina's west to east gas transmission project. At that time, China did not have a company capable of production. All imported compressors, American GE, German Siemens, etc. were used in the construction of the West first line and part of the west second line. The sky high price equipment was provided on-site guidance. Under the guidance of the State Council's localization, the compressor of Shengu long-distance pipeline officially entered the field of vision. Around 2011, the 20MW long-distance pipeline compressor of Shengu group was successfully commissioned, and then successfully entered the west to east gas transmission project, ensuring that the lifeline of the country is in its own hands. After the entry of Shengu group, the price of foreign units has shrunk significantly and the price has been reduced by more than half. So far, foreign units have basically lost their advantages in the domestic market competition and gradually withdrew from the Chinese market. Later, Sinopec also began to vigorously develop long-distance natural gas transportation. Sinopec's new Guangdong Zhejiang pipeline and China Russia natural gas pipeline project basically established the position of Shengu group as the core supplier of long-distance natural gas pipeline compressor for heart equipment. So far, the state of completely grasping China's destiny of high-end centrifugal compressor from abroad has ended. Shangu group participated in the supply of a long-distance pipeline compressor of Shangu group. It is said that the supply cycle is long, beyond t...

Precautions for oil used in hydraulic system of die casting machine The hydraulic system is the heart of the cold chamber die casting machine, and the hydraulic oil is the blood of the die casting machine. What problems should be paid attention to when using the hydraulic oil in the hydraulic system of the die casting machine? From two aspects: the first is the selection of hydraulic oil, and the second is the precautions for the use of hydraulic oil. 1、 Selection of hydraulic oil: For the die-casting machine, the quality of hydraulic oil directly affects the service life of the die-casting oil valve. The damage of any oil valve will affect the normal operation of the machine. If the oil selected at the beginning is inappropriate, the harm to the machine has already occurred, but it is not easy to find. In this way, it will be difficult to repair in the future. Therefore, the selection of hydraulic oil with appropriate variety and viscosity is the primary condition to ensure the normal operation of the system of automatic high precision die casting machine. 1. Selection of hydraulic oil varieties The variety selection of hydraulic oil is determined by the working environment and working conditions of hydraulic equipment. There are many kinds of hydraulic oil, including anti-wear hydraulic oil, anti combustion hydraulic oil, low pour point hydraulic oil, etc. Generally speaking, anti-wear hydraulic oil should be selected for the hydraulic system of aluminium alloy die casting machine. It is developed from anti rust and anti oxygen hydraulic oil. It not only has good anti rust and anti-oxidation, but also has more outstanding anti-wear performance and longer service life. 2. Selection of hydraulic oil viscosity When selecting hydraulic oil, it is important to select the appropriate viscosity grade. Temperature is the main reason affecting the viscosity of hydraulic oil. If the viscosity is too low, it will cause leakage and increase wear, resulting in the pressure of hydraulic system not meeting the standard, and the product quality does not meet the requirements. If the viscosity is too high, it will increase the suction resistance of the pump, easily produce cavitation, cause vibration and noise, reduce the response performance of the hydraulic system and reduce the action sensitivity. Generally, No. 46 hydraulic oil shall be selected in winter and No. 68 hydraulic oil shall be selected in summer. 3. Comprehensive technical and economic analysis of oil separation In the use of hydraulic oil, economy is an indispensable and important part. People often only pay attention to the price of oil products, ignoring the variety and quality of the selected oil. It is understood that the improper selection of oil products in the operation failure of hydraulic system is an important aspect. Therefore, in order to prolong the service life of oil products, save equipment maintenance costs, prolong the service life of hydraulic components and improve operation...

How to buy cold chamber die casting machine ? The selection of die casting machine is usually based on the clamping force, injection quantity and casting area. 1、 Determine the clamping force of alloy die casting machine The clamping force is the first parameter to be determined when selecting the die casting machine. The function of mold locking force is mainly to overcome the mold expansion force in the mold cavity, lock the parting surface of the mold, prevent liquid metal splashing and ensure the dimensional accuracy of the casting. The die locking force of the automatic high precision die casting machine is calculated as follows: F=k × p × s F --- calculate clamping force K --- safety factor P --- injection specific pressure S -- projected area The safety factor K is related to the complexity of the casting and the die casting process. It is generally taken as 1-1.3. For thin-walled complex castings, the parting surface of the die is greatly impacted due to the high injection speed, injection specific pressure and die temperature. Therefore, K should be taken as the larger value, and vice versa. II. Determine the injection quantity of the machine Injection quantity is an important parameter of intelligent die casting machine. It is the most permanent parameter when selecting the die casting machine, expressed in kilograms. Select a die casting machine with sufficient injection quantity - a die casting machine with injection quantity just equal to the blank weight of die casting parts shall not be selected. The usual choice is that the weight of die-casting blank should account for 25% - 85% of the injection volume. III. determine the projected area of parts The projection area is an important parameter for die casting model selection. The projection area mentioned here is not only the area of parts, but also the area of garbage bin and nozzle. The area estimation is generally obtained by dividing the clamping force by the injection specific pressure during die casting. For the existing beer pieces, the calculation of casting area should be divided into small regular shapes. (1) calculation of s of circle area with diameter D: S= Л d2/4 (2) calculation of square area s with side length a: S = A2 (3) calculation of rectangular area s with length a and width B: S = ab (4) calculation of trapezoidal area s with upper bottom a, lower bottom B and height H: S = (a + b) H / 2

cold chamber die casting machine pressure die casting machine refers to the application of about 2 times of high pressure [500-1500 kg / cm] to the final pressure of document speed injection in a very short time {MS setting conditions} after the injection. Therefore, it does not refer to the pressure value above, but to what device can effectively increase the pressure to higher than the high-speed final pressure to achieve the effect of pressurization. The final casting pressure refers to the pressure after about 0.3 seconds after the completion of injection, whether pressurized or not. Generally, the purpose of effective pressurization to improve the final casting pressure is to forcibly squeeze the liquid metal from the solidification shrinkage part that is rapidly solidified after filling the forming part, so as to prevent the so-called depression. At the same time, the residual pores and pin holes that are not removed from the forming part are compressed with high pressure to make them smaller. In order to achieve these two purposes, the higher the final pressure, the better the effect, but the higher the final pressure, the smaller the casting projection area. Therefore, larger casting machines and stronger molds are needed, which brings economic problems, so the range of 500-800 kg / cm is enough. In order to make full use of the pressurization effect, the time to rise to the final pressure after high-speed filling, that is, the pressurization rise time, is very important. Theoretically, pressurization should be maintained from the beginning of solidification to the end of solidification. If flash splashing occurs too early, and if the gate solidifies too late, it is impossible to replenish and pressurize the liquid metal at the forming part. In practical production, the pressurization rise time of medium pressure caster is generally set at 10-30ms. The pressurization device varies with the die casting machine manufacturer. Toshiba and Toyo machines only need to read the pressure gauge of the injection cylinder to see the difference between the pressure when the pressurization is effective and invalid. However, when the pressurization of Yubu machine is invalid, the pressure on the hydraulic oil supply side is the same as that on the discharge side. The pressure on the discharge side is called back pressure. When the back pressure is 0, it is 100% pressurized, and the pressure on the discharge side is above 0, When the supply side is below the pressure, it is the effective percentage of pressurization. The final pressure can be seen from the operating manual of the machine. alloy die casting machine It is occasionally seen at the casting site that flash is ejected every time, because the casting area is too large. When the flash is ejected, the casting area shall be confirmed immediately, and the allowable pressure value shall be calculated with the following formula Allowable pressure value kg / C ㎡ = clamping force kg × 0 9／casting area ...

aluminium alloy cold chamber die casting machine In die casting, the die is filled under the pressure of 15 ~ 120MPa. Pressure always works during solidification. Pressure is generated in the casting machine and applied to the melt through the piston, and the piston slurry molten metal is injected into the mold. By this method, castings with wall thickness less than 1mm and sharp edges can be produced. Higher casting pressure leads to higher metal flow viscosity (10 ~ 150m / a) and shorter filling time (150 ~ 20ms). This also means that when gradually in contact with the die surface, although the cooling speed is very fast, it will not solidify until the die is fully filled. For this reason, the best mold filling is very important. The high pressure acting on the die surface will also produce pressure to separate the two half dies, which is opposite to the corresponding "locking force". These forces put a great load on the die. Unlike in re cold casting, hot working steel, small box and solid die with stable clamping frame need to be used. The hydraulic unit associated with the machine is equipped with a high-pressure reservoir, and the control of the machine requires extensive automation. All this doubles the cost of machinery and tools. The high dimensional accuracy and surface properties of production, together with high output, make this process more economical, especially for long-term processes. These are also the reasons why and die casting are more widely used in aluminum alloys than other casting processes. The load of all die parts increases the pressure of the casting, so the sand core can not exceed a specific temperature (higher than that in low-pressure die casting). The metal core must be pulled out to allow the casting to be taken out of the mold. It cannot be used as a groove in practice, which also limits the design of die castings. However, in many cases, appropriate methods can be found to make up for this defect. Die casting has the following advantages: Very high dimensional accuracy is possible in casting parts with small tolerances; Lower mechanical tolerances and less machining are required; It can produce hollow cylindrical precision castings, such as bearing bodies, narrow drilled precision castings and castings engraved on castings; Thin wall gradually; Clean and polish the surface; aluminium alloy die casting machine: High productivity and short production time; die casting machine: Automated production.

Compressors are classified as follows according to different structural forms: according to their principles, they can be divided into: Reciprocating piston compressor, rotary compressor (turbine, water ring, turbine) compressor, axial compressor, jet compressor and screw compressor, among which reciprocating piston compressor is the most widely used. How are piston compressors classified ？ There are many classification methods and different names for piston compressor. There are usually the following classification methods: 1.According to the cylinder position (cylinder centerline) of the compressor, it can be divided into: (1) Horizontal compressor, all cylinders are horizontal (the center line of the cylinder is horizontal). (2) Vertical compressor cylinders are arranged vertically (vertical compressor). (3) For angular compressor, the cylinder is arranged in different angles such as L-type, V-type, W-type and star type. 2. According to the number of compressor cylinder sections (stages), it can be divided into: (1) Single stage compressor (single stage): the gas is compressed once in the cylinder. (2) Double stage compressor (two stages): the gas is compressed twice in the cylinder. (3) Multistage compressor (multistage): the gas is compressed many times in the cylinder. 3.According to the arrangement method of cylinders, they can be divided into: (1) Tandem compressor: multi-stage compressor with several cylinders arranged on the same shaft in turn, also known as single row compressor. (2) Parallel compressor: multi-stage compressor with several cylinders arranged in parallel on several shafts, also known as double row compressor or multi row compressor. (3) Compound compressor: a multi-stage compressor composed of series and parallel. (4) Symmetrical balanced compressor: the cylinders are arranged horizontally on both sides of the crankshaft whose journals are 180 degrees from each other, arranged in H-shape, and their inertial force can be basically balanced. (large compressors are developing in this direction). 4.According to the compression action of the piston, it can be divided into: (1) Single acting compressor: gas is compressed only on one side of the piston, also known as single acting compressor. (2) Double acting compressor: gas can be compressed on both sides of the piston, also known as compound or multi action compressor. (3) Multi cylinder single acting compressor: it uses one side of the piston for compression, while the compressor with multiple cylinders. (4) Multi cylinder double acting compressor: the two sides of the piston are used for compression, while the compressor with multiple cylinders. 5. According to the final discharge pressure of the compressor, it can be divided into: (1) Low pressure compressor: the end discharge pressure is 3 ~ 10 gauge pressure. (2) Medium pressure compressor: the final discharge pressure is 10 ~ 100 gauge pressure. (3) High pressure compressor: the final discharge pressure is 100 ~ 1000 ...

1. What are the main parts of the die casting machine? Answer: the die casting machine is mainly composed of closing mechanism, injection mechanism, ejection mechanism, power (hydraulic) system, control system It is composed of lubrication system, cooling system, etc. 2．What is the tonnage of die casting machine named after? A: the tonnage of die casting machine is named after the maximum clamping force (clamping force). For example, 180t die casting machine, its maximum clamping force is 180 tons. 3. What is the function of the closing mechanism of the die casting machine? Answer: the function of the closing mechanism is to install and fix the die and drive the moving die of the die-casting die to open or close the die. 4. What is the nominal pressure of the hydraulic system of the horizontal die casting machine? A: it is 12 MPa (or 120 kg / cm2). 5. What is the function of the injection mechanism? A: the injection mechanism is a key part of the die-casting process, which makes the metal liquid fill into the mold cavity at a certain speed and pressure from the injection chamber. 6. What are the cyclic action steps of the injection punch during normal production? Answer: the steps are: slow speed (from the beginning of the injection head to crossing the pouring port of the injection chamber)cold chamber die casting machine A rapid (the injection head allows the liquid metal to enter the runner and sprue) II. Fast (make the liquid metal go straight into the inner gate from the beginning to fill the mold cavity) Pressurization (when the liquid metal fills the mold cavity, the pressure of the injection cylinder increases rapidly to a certain value, and the filler metal is compacted and maintained for a period of time)horizontal die casting machine Tracking (at the same time of mold opening, the injection head continues to move forward some distance with the surplus material of gate sleeve) Return (the ejector head returns to the original state and completes a cycle) 7. What are the basic technical parameters of horizontal cold chamber die casting machine produced in China? Answer: there are (1) clamping force (KN), (2) injection force (KN), (3) jacking force (KN), (4) jacking stroke (mm), (5) moving formwork stroke (mm), (6) die thickness (mm), (7) injection chamber diameter (mm), (8) injection specific pressure (MPA), (9) maximum projected area of casting (cm2), (10) maximum metal pouring volume (aluminum alloy) (kg) (11) Working pressure of the system (MPA), (12) spacing within the column (mm), (13) main motor power (kw). 8. What process parameters can be adjusted during die casting production? Answer: (1) mold thickness, (2) mold closing speed, (3) mold opening speed, (4) mold closing time, (5) slow injection, (6) fast injection, (3) slow injection stroke, (8) fast injection stroke, (9) injection pressure (specific pressure), (10) tracking stroke, (11) tracking delay, (12) ejection stroke, (13) ejection speed, (14) ejection delay, (15) Cycle...