Product development of CFT-303.8 centrifugal chlorine compressor

Hangzhou Hangyang Compressor Co., Ltd. is one of the core enterprises of Hangyang Group. Its leading product is the development and production of various gas-medium compressor products for empty distribution sets and chemical processes (the variety and specifications have reached more than 110 Species); series of turboexpanders with empty distribution sets; series of C02 purification and liquefaction equipment for the alcohol industry; low-speed blowers, aerators, screw pumps and other products for the environmental protection industry. In 1999, after market research, the Compressor Company developed high-pressure natural gas (CNG) compressors (25MPa, 600, 1200m3/h) and centrifugal chlorine compressors for car filling to meet market demand. CNG compressor products have been supplied to North China Oilfield; centrifugal chlorine compressors have been put into trial operation test tests before leaving the factory.

   CFT-30/3.8 centrifugal chlorine compressor is a new product of Hangyang Compressor Co., Ltd. for large and medium-sized chlor-alkali production process matching or medium and long-distance chlorine transportation. As an updated product of Nessler's pump, this product has the advantages of high efficiency, energy saving, safety, no pollution and high operation rate. The new product is based on the technical parameter requirements of the Hangyang Compressor Company's 1999 market research report. The product drawing design was carried out in early 2000, and the trial production was invested in the second half of the year. The structure diagram of the compressor is shown in Figure 1. The new product has applied for a utility model patent from the State Intellectual Property Office and was approved in October 2000. The patent number is ZL00 2 555133.1.

  1 CFT-30/3. 8 type centrifugal chlorine compressor structure and technical parameters

  CFT type centrifugal chlorine compressor The whole unit includes: centrifugal compressor main unit, oil supply lubrication device, two-stage gas cooler, motor, unit internal piping system and instrument control electronic control device. The unit is a skid-mounted type with beautiful appearance, small floor space and easy installation and use. The working state of the main engine is that the motor drives the high-speed speed-increasing machine with the aid of the coupling. Through the single-stage speed change of the speed-increaser, the high-speed rotation of the two impellers on the high-speed shaft is realized. The chlorine medium obtains high-speed kinetic energy in the impeller flow path. The kinetic energy in the diffuser is converted into gas pressure energy; the chlorine medium obtains the pressure level required by the process through two energy conversions, and its flow parameters are determined by the precise design of the rotating speed of the working wheel and the geometric size of the impeller flow channel.

This product uses the American NREC software introduced by our company for calculation and design, and uses our company's five-axis CNC milling machine to process ternary flow impellers. The finished parts of the working wheel have also undergone 120% overspeed strength test (in accordance with the order P阗48— 86). The working wheel has undergone two dynamic balance checks before and after assembly (in accordance with HTA4421-91). The core components are carefully designed and manufactured to ensure that the final pressure, flow parameters and multi-efficiency of the compressor meet the design requirements.

   CFT-30/3.8 centrifugal chlorine compressor, the main technical parameters of the product are as follows:

Medium: Chlorine (water content≤400×10-6)

Type: centrifugal, ternary flow impeller, two-stage compression, water-cooled

Exhaust volume: 1800m3/h (standard state)

Inlet pressure: normal pressure~86.6kPa(A)

Inlet temperature: ≤25℃

Exhaust pressure: 0.38MPa(A)

Speed: 22470r/min

Shaft power: 145kW

Equipped with motor: model Y315L1-2

Power 160kW, speed 2982r/min

Voltage 380V Frequency 50Hz

The area occupied by the host (length × width × height): 2650mm × 1500mm × l550mm

  2 The deficiencies of the old-fashioned Nessler pumps and a small amount of turbo-chlorine compressors commonly used in chlor-alkali processes

  In the early stage of the development of new products, we investigated the common supporting equipment in the current chlor-alkali process, such as old-style Nessler pumps and a small amount of turbo-chlorine compressor products. In the operation practice, these equipments have many shortcomings, mainly in:

  ① The operation of Nessler's pump relies on a large amount of concentrated sulfuric acid (98% content) as a sealant and coolant. If compared with the same flow rate of this product (calculated based on two Nessler pumps), the annual consumption of concentrated sulfuric acid is about 60 tons, calculated at the market price of 380 yuan per ton, the single operating cost of the Nessler pump will increase by 2.28 Ten thousand yuan, poor practical economy, and pollution, affecting environmental protection. Secondly, the annual replacement of wearing parts for the two Nessler pumps is about RMB 120,000. In addition to the actual power consumption of the motor, the shaft power of the two Nessler pumps is about 50kW than this product. An increase of 195 thousand yuan. In terms of the above three items, the annual operating cost of the two Nessler pumps is more than 330,000 yuan more than the new product.

②The small number of turbo-chlorine compressors currently available in the industry have improved compared with the previous Nessler pumps, but due to various defects in the structure and component selection, the equipment performance parameters often fail to meet the expected indicators. Such as low pressure, low flow rate and leakage of gas pollution, frequent replacement of wearing parts, increased power consumption caused by mechanical loss, and decreased efficiency of the host.

Here are some of the opinions we have obtained through research for reference for peer research:

  (1) The flow channel design and processing of the main machine's working wheel is the key to whether the performance of the equipment can be guaranteed. To ensure that the multi-party efficiency of the host is in the range of 65% to 70%, it is necessary to borrow advanced software technology and hardware equipment.

(2) The connection method between the high-speed impeller and the main shaft, such as the cylindrical surface connection structure type, the mechanical assembly during high-speed operation, the dynamic balance adjusted before assembly will be destroyed, and the high-speed rotating centrifugal force will gradually increase. Affect the stability of performance parameters, and damage the impeller in severe cases.

(3) In the case that the speed increase ratio is not too large, if the speed increaser is designed with a two-stage or three-stage speed change, the moving parts increase and the volume increases, and the comprehensive operation accuracy of the combined parts will be greatly reduced, resulting in vibration and noise , Increased wear and tear. Moreover, the design of speed increasing gears, such as the use of spur gears, cannot offset a certain axial thrust, which will increase the burden of high-speed bearings.

  (4) The oil supply device has a huge structure, poor appearance, mismatched oil supply, low efficiency and many failures.

  (5) The structure of the coupling should consider that both the axial and radial directions should have appropriate automatic adjustment and compensation. This part is also the place where failures often occur during mechanical operation.

  (6) The surface of the flow channel in contact with gas, especially the flow channel surface of the volute, is very susceptible to corrosion by chlorine gas, and effective anti-corrosion treatment should be taken.

  3 Main technical features of CFT type chlorine compressor

(1) The connection method between the working impeller and the high-speed main shaft adopts the most reliable triangular shaft connection structure with a slope in the axial length in the world's technical field, which is safe and reliable, and ensures the matching accuracy of high-speed rotating parts and the overall assembly rigidity. This is the high-tech advanced technology of today's high-speed mechanical structure.

  (2) The design of the ternary flow channel of the working wheel uses American NREC software technology; the processing and shaping of the working wheel flow channel is processed by a five-axis CNC milling machine imported from Germany to ensure that the host machine can obtain high efficiency performance.

  (3) The speed increaser is a helical gear single-stage transmission structure. The overall structure is compact, there are few moving parts, and the overall operation accuracy is improved. The axial force generated by the impeller on the high-speed shaft is transferred to the low-speed shaft, and vibration and power consumption will be greatly reduced. The high-speed shaft is supported by tilting-pad bearings, which can be automatically compensated in the radial direction; the low-speed shaft is supported by the thick-walled thrust bearing, and the thrust surface of the bearing can bear part of the remaining axial force. The structure of the speed increaser is reasonable and beautiful. Prior to the assembly of the main engine, the speed increaser shall be individually tested and qualified by dry running test according to the HAl482-92 specification.

  (4) The unit is equipped with independent high-efficiency oil supply device, compact structure and beautiful appearance. According to the requirements of high-speed machinery and equipment, a certain oil supply margin should be ensured. The alarms and interlocking requirements of the start-up of the oil pump, the blockage of the oil filter, the excessively high oil supply temperature and the low oil supply pressure are all controlled by the instrument. At the same time, the fuel supply device also quotes the practical technology of our company’s turboexpander, and is equipped with a backup pressure fuel tank. When there is no backup power supply in an emergency power failure, it can ensure continuous fuel supply for a certain period of time to prevent the inertial movement of high-speed rotating parts. A failure occurred.

  (5) This machine is equipped with a complete instrument and electrical control device. The instrument and electrical control of the unit adopts two-level control mode, on-site and side cabinet, and the main parameters are also reserved for the central control interface. Carry out instructions, alarms and interlocking controls on various operating parameters of the host. The start and stop conditions of the main motor are also controlled by instrument and electricity.

  (6) The transmission mode of the main machine of the chlorine compressor adopts a new high-speed flexible diaphragm coupling that fully complies with the American APl617 standard, which is a high-precision technology product. It has the characteristics of electrical insulation, strong vibration damping, small additional bending moment, anti-loosening protection, and long operating life.

  (7) Chlorine is a highly toxic gas, and the leakage of toxic gas should be strictly controlled. This product uses our company's mature turbo-oxygen compressor shaft seal technology, and is equipped with a differential pressure control type labyrinth shaft seal structure. Dry inert pressure gas is used to implement two-way air sealing, which not only leaks chlorine gas from the shaft end gap, but also seals the lubricating oil from the bearing gap to the casing.

  (8) Chlorine gas is highly corrosive, and it is characterized by the fact that moist chlorine gas or chlorine gas medium at high temperature will have a strong corrosive effect on almost all ferrous metals. The chemical properties of chlorine are also very active, and high-temperature chlorine will decompose. The material selection of the parts in contact with chlorine, the surface treatment of the runner, the deformation resistance of the temperature rise parts, etc., are all considered in the design of this product.

4 Conclusion

Since Hangyang designed and manufactured its first centrifugal air compressor product in 1970, more than 200 sets of turbo compressor products (medium air, oxygen, nitrogen) have been applied in industry (not including more than 300 sets) Turbo expander products and high and low speed blower products). Hangyang's turbine technology and product quality have a leading advantage in the air separation industry.

   Our self-developed CFT-30/3.8 type chlorine compressor has greater flexibility in matching the technical parameters of its products to the equipment of different scale process flow in the chlor-alkali industry. For a large-scale chlor-alkali plant, the use of multiple machines in parallel will not only reduce the total equipment investment and reduce the number of standby machines, but also be more adaptable to changes and adjustments of flow during operation, and the total energy consumption of the complete set is also reduced. Our company's CFI' type chlorine compressor products, before delivery, all units have passed the test run test of the whole machine and passed the commissioning. After leaving the factory, the equipment in the user unit does not need to be unsealed and reinstalled, and can be directly put into use according to the requirements of the product manual Operational use.

  For the different requirements of the chlor-alkali process in terms of flow and pressure parameters, we will strive to develop more varieties of chlorine compressor series products, and continue to apply the latest turbine technology in product development to meet user needs.