Nanjing East Chemical Co., Ltd. purchased the ITEL80 horizontal hydrogen compressor from Germany. Due to the difference between the actual operating conditions such as gas supply volume and inlet pressure and the original design conditions, it has not been put into use for a long time. At the beginning of this year, Nanjing Dongfang Chemical Co., Ltd. expanded the system and equipment. In order to make the compressor reusable, we entrusted our factory to modify it to adapt to the new working conditions.
2 original compressor parameters and modified compressor parameters
21 original compressor parameters
Compressor type: single row horizontal double acting cylinder diameter: D=300mm piston stroke: S=160mm piston rod diameter: d=60mm speed: n=480r/min maximum allowable piston rod load: F=110kN compressor shaft power: N=182kW intake pressure: ps=25MPa (absolute)
Exhaust pressure: pd=34MPa (absolute)
Safety valve setting: pA = 375MPa (absolute)
Intake air temperature: 40 relative clearance: a=009 gas supply: Qn=11500Nm 3 /h gas composition: H2=9772%CH4=10%N 2=10%H2O=028% 22 Compressor parameters after transformation
Intake pressure: ps=20MPa (absolute)
Exhaust pressure: pd=31MPa (absolute)
Safety valve setting: pA = 345MPa (absolute)
Gas supply: Qn8000Nm 3 /h transformation principle is to use the original compressor components, such as electric motors, transmission components, fuselage, piston rods and auxiliary Z machines, etc., and only change cylinders, pistons, piston rings, etc. to achieve transformation Purpose, to minimize the cost of renovation.
3 choose the transformation plan
31 transformation plan one
Keep the original compressor structure unchanged, directly change the inlet pressure from 25MPa to 20MPa, the exhaust pressure from 34MPa to 31MPa, and the safety valve setting from 375MPa to 345 MPa. The thermal displacement is 93m3 / Min, equivalent to the air supply quantity Qn=9774Nm3 /h, which is 85% of 11500Nm3 /h, the maximum gas force is 96/122kN, the indicated power is 180/220kW, and the shaft power is 198/241kW. At this time, the maximum gas force is over 122kN. The maximum allowable load value of the piston rod provided by the user is 110kN, and the indicated power and shaft power are also greater than the original compressor design conditions. In this way, it is necessary to perform all strength calculations on the compressor transmission components, etc., it is possible to completely replace the transmission components, and the motor has to reselect a larger power motor.
This solution obviously does not meet the principle that the user changes the original compressor components as little as possible.
32 transformation plan two
With the maximum piston rod load of the original design as the limiting condition, the inlet pressure is 20 MPa, the exhaust pressure is 31 MPa, and the safety valve setting is 345 MPa. At this time, only the cylinder diameter is changed from 300 mm to 280 mm for thermal calculation (calculation) The results are shown in Table 1). According to the calculation results, the displacement of this scheme is 81m 3 /min, and the gas supply is Qn=8520Nm3 /h, which is 74% of the original compressor supply, meeting the requirements of the user's transformation conditions. The maximum gas force is 84/107kN, the indicated power is 158/192kW, and the shaft power is 173/211kW, which are smaller than the original compressor design conditions. In this way, it is only necessary to change the cylinder diameter of the compressor, while other components such as the motor and the transmission components remain unchanged, in accordance with the principle of user modification.
Reconstruction design of 4 cylinders, pistons, etc.
According to the transformation plan, the diameter of the original compressor cylinder is changed from 300mm to 280mm. Therefore, the parts involved in the cylinder diameter change, such as cylinder liner, piston, piston ring, etc., should be redesigned, manufactured and replaced, and the remaining compressor components are kept. constant. To this end, the compressor cylinder, piston and other components were mapped (the schematic diagram of the original compressor cylinder components is shown in Figure 1). Redesign cylinders, pistons, piston rings and other parts according to the survey.
Actual measurement: cylinder bore: 32005mm cylinder liner outer diameter: 31994/32008mm cylinder liner inner diameter: 301mm (matching with cylinder head)
30005mm (piston movement part)
Refer to the measured dimensions of the original cylinder liner when designing the cylinder liner. The outer diameter of the cylinder liner is the same as the outer diameter of the original cylinder liner, and is designed to be 320m6. In order to utilize the original cylinder head as much as possible, the inner hole of the cylinder liner is designed to be stepped. In the installation of the cylinder head, the inner diameter of the cylinder liner is the same as the original size in order to utilize the original cylinder head. Only change the diameter of the piston to 280H7. The cylinder liner material is QT600-3, which is equivalent to the original cylinder liner material.
The design of the piston and piston ring is also carried out with reference to the original piston and the piston ring, except that the relevant dimensions of the outer diameter and the like are reduced by 20 mm. The tolerance of each part is also determined according to the measured dimensions of the original. The material is HT250, which is consistent with the original piston material.
5 Comparison of the original design working conditions and the stress conditions under the modified working conditions
In order to ensure the safe operation of the compressor after the transformation, it is necessary to calculate the force of each moving part of the compressor and compare it with the force under the original design conditions. If the force of each component is less than the force of each component under the original design conditions, the components may not need to be intensity-calculated. Otherwise, intensity calculations must be performed on each moving part to ensure safe operation.
The force of the compressor mainly includes the gas force, the inertial force and the friction force generated when the crank link mechanism moves, and the combined piston force combined by these forces. Also calculate the total tangential force acting on the crank linkage.
Since the manufacturer did not provide the compressor details, in order to facilitate the calculation, we have mapped the crankshaft linkage and piston assembly of the original compressor to obtain the basic calculation data. The actual calculated data after surveying and mapping is as follows: piston component quality: 995kg crosshead assembly mass: 440kg linkage assembly mass: 665kg (take the small diameter of the connecting rod 20kg)
Total mass of reciprocating part: Ms=1635kg Link length: l=045m Curved radius: r=008m Ratio of crank radius to link length: =0178 Piston assembly mass after transformation: 901kg reciprocating part Total mass: Ms= The remaining data of 1541kg are the same as the original compressor.
According to the calculation results, the force of the compressor after the transformation is less than the force of the compressor when the original design scheme is used. Therefore, it is not necessary to perform strength calculation on each moving part of the compressor, and the modified compressor can operate safely.
6 compressor inspection, installation and commissioning
Since the compressor has been idle since the installation, in order to prevent the corrosion of the parts, the blockage of the pipeline and other factors affecting the normal driving, the user requires that in addition to the transformation of the original compressor, the components of the unit must be dismantled and cleaned. Make sure the machine is working properly and drive once successfully.
The main contents of the dismantling and cleaning are as follows: (1) compressor connecting rod, crankshaft, crosshead and bearing, etc.; (2) compressor intake valve, exhaust valve, outlet check valve and safety valve; (3) sealing Components; (4) compressor auxiliary ZZ machine, including oil supply system, cooling system, etc.; (5) electrical instrumentation and other components.
After disassembly and cleaning, reassemble. The newly manufactured cylinder liner, piston assembly, etc. are assembled in place. Check the axial clearance of the cover side and the shaft side are 262mm and 270mm respectively. After the installation is completed, the 4h no-load test is carried out, and the operation is good. After passing the user's acceptance, it is put into operation with load. The machine runs smoothly and the temperature rise of the lubricating oil is all within the normal range. Exhaust pressure and exhaust volume have fully met the predetermined requirements and are now in normal use.
7 Conclusion
The results of compressor commissioning and official operation indicate that the compressor retrofit was successful. The user only used a small amount of expenses, which enabled a long-term idle device to be put back into use, achieving the purpose of equipment expansion and transformation.
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