【 Weak current College 】 centrifugal compressor home ideas

Introduction: the characteristics of a centrifugal compressor, application status and development trend; the difficulty of centrifugal compressor, focus and strategy; develop the General steps for centrifugal compressors.
Keywords: localization of centrifugal compressor

I. characteristics of centrifugal compressors.

Centrifugal compressor as a speed type compressors, has the following advantages:

1. in the same cold, especially in the large capacity, compared with screw compressor, eliminates the vast oil separation unit, unit of weight and size is relatively small, small footprint;

2. simple structure, compact centrifugal compressor, fewer moving parts, reliable, durable, low operating cost;

3. easy to achieve multiple levels of compression and a variety of evaporating temperature, easy to implement, of intermediate cooling power consumption is low;

4. centrifuge Lube of mixed in with the group very little heat exchanger for heat transfer effect is small, the unit has a high efficiency.

Has the following disadvantages:

1. the rotor speed higher, in order to ensure the width of the impeller must be used for large medium flow, not suitable for small flow occasions;

2. single-stage compression ratio low, in order to get a high pressure ratio shall be multilevel impeller, generally also used speed gear;

3. for the surge is the inherent shortcomings of centrifugal compressor, turbine shall add anti-surge system;

4. the same crew operating mode without major changes to apply the narrower scope.

II. application of centrifugal compressor and trends.

At present, most of the centrifugal chiller market is mainly composed of EU and us some refrigeration enterprises in occupies. Compare the famous enterprises such as Te, Kalee, York, McQuay, AXIMA (formerly Sulzer), EBARA, Mitsubishi, relying on advanced technology and good technology-driven centrifugal chiller market. Domestic enterprises mainly for Chongqing General, early introduction of technology to develop NREC centrifugal chiller. With the development of the society, the user needs of increasingly high cooling capacity, due to the energy-saving requirements makes centrifuge group has become an increasingly widespread market. Some domestic air-conditioning manufacturers such as Haier, o g Ma, gree and beautiful (and the Chongqing General merged) have introduced their own centrifugal chillers. Large cold and AXIMA cooperation developed centrifugal chillers and district heating of centrifugal heat pump unit. Most of these centrifuge group using environmentally-friendly refrigerant R134a.

With the growing tension in the form of energy, saving energy is one of the major product development trends. As China's urbanization level, building energy consumption is increasing. Highest performance coefficient of centrifugal chillers will undoubtedly become the market's hotspot in recent years, sales of centrifugal chillers.

Most of the developing country centrifugal chiller Enterprise just buy imported compressors, basically no profit. Foreign centrifuge manufacturers will not easily sell their own core technology, to develop centrifugal compressor, only to go the path of independent development. With the design and manufacturing technology continues to mature, making the domestic development of centrifugal compressors.

III. development of centrifugal compressors of pain, the focus and strategy.

Development of a centrifugal compressor includes many aspects: thermodynamic calculation, the strength and vibration calculations, structural design, materials selection, processing and manufacturing process design, automatic control and adjustment of design, and driver type selection, etc. It difficult to focus mainly has following several aspects:

1. impeller design

Rotor as centrifugal compressor movement part, the core part of the impeller. Now the largest centrifuge manufacturers at home and abroad are made of three-dimensional flow impeller design methods. ASP stream requires that designers have numerical simulation, computational fluid dynamics, fluid mechanical flow field theory and other highly specialized knowledge. Most domestic company technicians do not have the expertise to design efficient, only ternary impeller and the cooperation of scientific institutions and universities. College of experts in the field of centrifugal compressor mainly Shanghai Jiaotong University Professor of the Valley to the outline, Xi'an Jiaotong University, Professor Wang Shang Jin. Ku Professor has long been engaged in research, the centrifuge has presided over the complete 6 National Natural Science Fund project, design of three-dimensional flow in centrifuge, compressor test, monitoring and control system surge and so have the in-depth research, which he completed in multistage centrifugal compressor and pneumatic design technology and application "project received the 2004 National Science and technology progress second prize. Wang Xi'an Jiaotong University led by Professor Nasser machine pump research group, to the unique "controllable" Vortex impeller design theory, petrochemical, and other areas of unit of outstanding applications.

2. the processing of the impeller

Design by three-dimensional flow theory of impeller blade shape typically space surface, blades and impeller made of machined is focused, it is difficult. For ternary impeller, common processing there are two primary ways:

1) three-body welding: i.e. Roulette, leaf, wheel cover respectively manufacturing. This processing method is relatively simple to equipment requirements, wheel, wheel cover just car overall is enough. Some leaf processing to trouble, first to take advantage of a three-axis machine tools milling leaves the stencil, and then add the following blades for heat treatment, the pressure to get the desired shape of leaves. Finally the blades welded to the roulette, then move the wheel cover welding good. In this case the device is probably needed three-axis milling machine, heat treatment furnaces, hydraulic press and other required some conventional equipment, the required investment is relatively low, more suitable to start doing.

2) overall milling system: is the roulette and the blade is in use more coordinate overall milling system equipment get a semi-open impeller. To avoid interference, the international processing of the impellers are mostly use five-axis machining centers. A five-axis setKeep millions from millions to probably more than the cost is very high. To processing 600mm impeller, for example, domestic five axis bed about 350 million RMB, imported five axis bed about 480 million RMB. Through the four coordinates of the rotating bench lathe inclined towards the four-way impeller overall milling system coordinates, if leaves thick relatively large, interfering in four coordinates is inevitable. 4 coordinates of the equipment is relatively cheap, about 100 million RMB.

3. a rotor in the calculation of critical speed

Design of critical speed is the rotor speed is an important factor to consider, rotor speed to avoid critical speed. Calculation of critical speed of the general law in General, market lol has specialized calculation of critical speed of the software, you can own development calculation software.

4. anti-surge system design

By centrifugal compressor working mechanism of the surge is inherent in the nature of the centrifuge, cannot be eliminated, but can be avoided by effective way. Occurrence of centrifugal compressor surge causes: flow too low and the condensing pressure is too high. Surge damage to the unit, be quite seriously anti-surge system design.

5. bearing design

Centrifugal compressor generally use speed gears, rotor speed is generally at 5000RPM, using plain bearings, sliding bearing design is also an important focus of the development of centrifuge.

IV. development of centrifugal compressors of general steps:

1. collect, study and centrifugal compressors centrifugal chillers of related standards.

2. organizes the concerned personnel to learn the basics of centrifugal compressor, using the unary flow theory and design of the level of the compressor.

3. organizes the concerned personnel to related research institutes and professional manufacturer of learning.

4. cooperation with research institutes for the design of the ternary impeller.

5. research and development unit.

6. improved prototype testing.

5 ideas

The 1950s, scientists Professor Wu Chung-Hua three-dimensional flow theory of turbomachinery, laid the three-dimensional flow design rationale. Some large companies such as abroad NREC, according to this theory developed the design of a centrifugal impeller machinery and processing software.

Our scientists and scientists also conducted a number of fruitful research centrifugal compressor design and processing carried out in-depth research and developed a series of research results, compared with foreign countries. Proposed domestic refrigeration enterprises hold high the banner of national industries, developed in the true sense of the domestic production of centrifugal compressors.