ÀÚµ¿·Î±×ÀÎ
ÄÁÅÙÃ÷ | contents
ÀϹݰԽÃÆÇ
Q&A°Ô½ÃÆÇ
°øÇÐ S/W
½ºÅ͵ð | study
´ÜÀ§È¯»ê
³óµµ°è»ê
ÀϹÝÈ­ÇÐ
È­°øÀϹÝ
È­°ø½Ç¹«

   
  ÆßÇÁ ¼º´É°î¼± ¹× ºñ¼Óµµ °ü·Ã ¹®ÀÇ
  ±Û¾´ÀÌ : ¸¶µ¿¾²   °íÀ¯ID : com2356     ³¯Â¥ : 19-12-14 17:03     Á¶È¸ : 2831    
   ÆßÇÁ suction ºñ¼Óµµ ½Ä.PNG (15.3K), Down : 4, 2019-12-14 17:03:55
¾È³çÇϼ¼¿ä,
È­°ø °ü·Ã ¼­Àû(Gas Conditioning & Processing)À» Àдø Áß pump ³»¿ë¿¡ ´ëÇØ ±Ã±ÝÇÑ »çÇ×ÀÌ »ý°Ü Áú¹® ³²±é´Ï´Ù.
¹Ù»Ú½Ã°ÚÁö¸¸ ´äº¯ ÇØÁÖ½Ã¸é °¨»çÇÏ°Ú½À´Ï´Ù.

1. ÆßÇÁ ¼º´É°î¼± Áß NPSHr Curve¿¡ ´ëÇÑ ³»¿ëÀÔ´Ï´Ù. ¾Æ·¡ ¿µ¹®Àº ¼­ÀûÀÇ ¿ø¹®À̸ç, Á¦°¡ ±Ã±ÝÇÑ »çÇ×Àº ´ÙÀ½°ú °°½À´Ï´Ù.
 - ³ë¶õ»ö À½¿µÀ¸·Î ³ªÅ¸³½ ºÎºÐÀÇ Àǹ̰¡ ¹«¾ùÀÎÁö ±Ã±ÝÇÕ´Ï´Ù.
 - ¹°ÀÌ Áõ¹ßÀá¿­/ºñ¾ÐÃ༺ÀÌ ³ô±â ¶§¹®¿¡ cavitation¿¡ ÀÇÇÑ °á°ú°¡ severeÇÏ´Ù°í Çϴµ¥, ¿Ö ±×·±Áö ÀÌÀ¯°¡ ±Ã±ÝÇÕ´Ï´Ù. Áõ±â¾ÐÀÌ ³ô°í Áõ¹ßÀá¿­ÀÌ ³·Àº hydrocarbonÀÇ °æ¿ì´Â cavitation¿¡ ÀÇÇÑ °á°ú°¡ ¹°º¸´Ù´Â ´ú severeÇÏ´Ù°í Çϳ׿ä.

'The NPSHr shown on a pump curve is sometimes confusing. The units on NPSHR are m[ft] of liquid pumped. However, the NPSHR test is run on water. NPSHR represents the NPSHA when the pump experiences a 3% head loss as the NPSHA is reduced. Cold water is the most severe test of NPSHR. Water has a very high latent heat of vaporization and is essentially incompressible. Pump cavitation in cold water can be very destructive.'


2. ÆßÇÁ suction specific speed(ÀÌÇÏ Nss)¿Í °ü·ÃÇÏ¿©, Nss°¡ 120À» ³ÑÀ¸¸é NPSHA°¡ NPSHRº¸´Ù Ä¿µµ cavitationÀÌ ÀϾ ¼ö ÀÖ´Ù°í Àú¼úµÇ¾î ÀÖ½À´Ï´Ù. Nss ½ÄÀº À¯Ã·ÇÏ¿´À¸¸ç, À¯·®¿¡ ºñ·ÊÇÏ°í NPSHR¿¡ ¹Ýºñ·ÊÇÕ´Ï´Ù. µû¶ó¼­ À¯·®ÀÌ Ä¿Áú ¼ö·Ï Nss°¡ Ä¿Áö¹Ç·Î cavitationÀÌ ¾È ÀϾ °ÍÀ̶ó ÀÌÇØ°¡ µÇ´Âµ¥, Ã¥ ³»¿ë¿¡¼­´Â À¯·®ÀÌ ÀÛ¾ÆÁö¸é Nss°¡ Ä¿Á®¼­ cavitationÀÌ ÀϾ´Ù°í µÇ¾îÀֳ׿ä... ¿ø¹®Àº ¾Æ·¡¿Í °°Àºµ¥ Á¦°¡ À߸ø ÀÌÇØÇÑ °ÍÀÎÁö ±Ã±ÝÇÕ´Ï´Ù.

'Cavitation may occur at low flow conditions if Nss is greater than about 120. It has been shown that in water wervice, cavitation can occur at 30~40% of best efficiency flow even though the NPSHA is 2.0 to 2.5 times greater than the NPSHR from the manufacturer's curves. This is due to internal recirculation in the impeller. In hydrocarbon service this phenomena is less troublesome, but in any case it is recommended that pump with an Nss greater than 200 be avoided.'

½ºÅ×Æijë Stefano   19-12-16 14:22
A1-1) ³ë¶õ»öÀ¸·Î Ç¥½ÃÇÑ ºÎºÐÀÇ ¼³¸íÀº <(¿ø½ÉÆßÇÁ¿¡¼­) "NPSHR"°ªÀº ÆßÇÁ°¡ (CavitationÀÇ ¿øÀÎÀ¸·Î) ¹èÃâ¾Ð·Â(Head)ÀÌ 3%ÀÌ»ó ÁÙ¾îµéÁö ¾Ê±âÀ§ÇØ À¯ÁöÇؾßÇÒ NPSH°ªÀ» ³ªÅ¸³½´Ù.> ÀÔ´Ï´Ù.  ¶ÇÇÑ ÀÌ ±Û¿¡¼­´Â Ç¥ÇöÇÏÁö ¾Ê¾ÒÁö¸¸ Head°ª¼Ò´Â ¾ø´Ù°í Çصµ ½ÇÁ¦·Î CavitationÀ» ÀÏÀ¸Å°Áö ¾Êµµ·Ï ÇϱâÀ§ÇØ À¯ÁöÇØ¾ß ÇÒ ÃÖ¼Ò°ªÀÇ NPSHÀ» ¸»ÇÕ´Ï´Ù.   

3%·Î Á¤ÇÑ °ÍÀº Pump Manufacturer Çùȸ¿¡¼­ °æÇè¿¡¼­ ¾òÀº °ª¿¡ ¹ÙÅÁÀ» µÎ°í ÇùÀÇ¿¡ ÀÇÇØ Á¤ÇÑ °ª¿¡ ÇØ´çÇÏ°í ½ÇÁ¦·Î´Â ´õ Å« ¿©À¯Ä¡¸¦ °®´Â NPSHa¸¦ ÃëÇÕ´Ï´Ù. 

A1-2) ¹°ÀÇ Áõ¹ßÀá¿­ÀÌ Å©°í ¾ÐÃ༺ÀÌ ³·¾Æ¼­ ³Ã¼ö¿¡¼­ÀÇ CavitationÀÌ ´õ Æı«·ÂÀÌ ³ô´Ù´Â °ÍÀº ÀÏ´Ü Áõ±â·Î µÈ ÈÄ ÀÀÃàµÇ·Á¸é ¾Ð·ÂÀÌ Å©°Ô ´Ã¾î³­ µÚ¿¡ ÀÀÃàÀÌ ÀϾ´Ù´Â °ÍÀÌ°í Implosion(ÀÀÃàµÈ Áõ±â°¡ ¼ø½Ä°£¿¡ ÀÀÃàÀÌ ÀϾ´Â Çö»ó)ÀÌ ³ªÅ¸³¯ ¶§ ±Ý¼Óº®¿¡ ÁÖ´Â Ãæ°ÝÀÌ Å©±â ¹®ÀÔ´Ï´Ù.

CavitationÀº ¾×ÀÇ À¯ÀÔ ¾Ð·ÂÀÌ Áõ±â¾ÐºÁ´Ù ³·¾ÆÁ® Impeller ¾È¿¡¼­ ¾×ÀÇ ÀϺΰ¡ Áõ¹ßÇϸ鼭 ³ªÅ¸³ª´Â Çö»óÀε¥ Áõ¹ßµÈ ¾×ÀÌ ÀÀÃàµÇ·Á¸é Áõ¹ßÀá¿­À» ¹æÃâÇؾßÇÏ°í ¾Ð·ÂÀÌ ³ô¾ÆÁ®¾ß ÇϹǷΠÁÖ·Î Impeller TipºÎºÐ°ú Diffuser ¿¬°áºÎÀ§¿¡¼­ ¿îµ¿¿¡³ÊÁö°¡ °¨¼ÒµÇ¸é¼­ Á¤¾ÐÀÌ »ó½ÂÇÒ ¶§ ³ªÅ¸³­´Ù°í ÇÕ´Ï´Ù.  Áõ¹ßÀá¿­ÀÌ Å©´Ù´Â °ÍÀº Áõ±â°¡ Impeller Tip±îÁö À̵¿ÇÏ¿© ¾Ð·ÂÀÌ ³ôÀº °÷¿¡¼­ ÀÀÃàÀÌ ÀϾ ¼ö ÀÖ´Ù´Â °ÍÀ» ¾Ï½ÃÇÏ´Â °ÍÀÌ°í ¾ÐÃàÀμö°¡ ÀÛÀ» ¶§ Æı«·ÂÀÌ ´õ Å©´Ù´Â °ÍÀº °í¹«°øº¸´Ù ¼è±¸½½¿¡ ÀÇÇÑ Ãæ°ÝÀÌ Å« °ÍÀ¸·ÎºÎÅÍ ÁüÀÛÇÒ ¼ö ÀÖ½À´Ï´Ù.   

A2) Pump Specific Speed´Â 1m3/sÀÇ À¯·®À» 1 mH Ç°¾î¿Ã¸®´Âµ¥ ÇÊ¿äÇÑ ¿ë·®°è¼ö¿¡ ÇØ´çÇÕ´Ï´Ù.  ÀÌ´Â Pump Impeller ÇüÅ¿¡ µû¶ó ±× ¹üÀ§°¡ ´Ù¸£°í ¶Ç CavitationÀÌ ³ªÅ¸´Â ¿µ¿ªµµ ´Ù¸¨´Ï´Ù.  ÀϹÝÀûÀÎ Nss¿µ¿ªÀº  Radial VaneÀÎ °æ¿ì 11~38  Mixed Flow 82~160, Axial Flow 100~500ÀÌ°í CavitionÀÌ ³ªÅ¸³ª´Â ¿µ¿ªÀº ÆßÇÁ ±¸Á¶¿Í ¹ÐÁ¢ÇÏ°Ô ¿¬°üµÇ¾î ÀÖ½À´Ï´Ù.  ¿ø½ÉÆßÇÁÀÇ °æ¿ì Nss 120À̶ó¸é ¸Å¿ì Å« ÆíÀÌ¶ó¼­ Å« NPSHRÀ» ¿ä±¸ÇÕ´Ï´Ù.  (Ref:  Hermatic Pumps Handbook)

Áú¹®¿¡¼­ Nss 120º¸´Ù Å«°æ¿ì NPSHA°¡ NPSHRº¸Å¸ ÈξÀ Å«°ªÀ» °¡Áø´Ù´Â °ÍÀº °íü¸éÀÌ °í¼ÓÀ¸·Î ȸÀüÇÒ °æ¿ì °íüǥ¸é¿¡¼­ »óÅÂÀû À¯¼ÓÀÌ Áõ°¡ÇÔ¿¡ µû¶ó º£¸£´ºÀÌÀÇ ¿ø¸®¿¡ ÀÇÇØ Á¤¾Ð(Static Pressure)ÀÌ Å©°Ô ³·¾ÆÁ® Áõ±â¾Ðº¸´Ù ³·¾ÆÁú ¶§ ³ªÅ¸³ª´Â Çö»óÀÔ´Ï´Ù.  ¹Ù´å¼ÓÀ» ´Þ¸®´Â ¹èÀÇ ¸Ç ¹Ø¿¡ À§Ä¡ÇÏ°í ÀÖ´Â ½ºÅ©·ù¿¡¼­µµ °í¼ÓÀ¸·Î ȸÀüÇÏ´Â Impeller Tip¿¡¼­ BubbleÀÌ »ý¼ºµÇ´Â °ÍÀ» º¼ ¼ö°¡ ÀÖ½À´Ï´Ù.
   

Copyright 1999.07.10-Now ChemEng.co.kr & 3D System Engineering. (mail : ykjang@naver.com, call 010-4456-8090)