Types of chillers – Overview Centrifugal chiller - components, controls and applications Screw chiller – Components, controls and applications VSD application considerations & Benefits…Full description
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Descripción: Over 300 sequences and many unsolved problems and conjectures related to them are presented herein. These notions, definitions, unsolved problems, questions, theorems corollaries, formulae, conject...
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In this paper a detailed study is presented on magnetohydrodynamic fluid flows with their basic governing equations. Basic concept of magnetohydrodynamic is discussed in detail. The results of various problems done by researchers are presented and ad
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Drill bit types and their applications Classification of bits
Rotary bits drill the formation using primarily two principles: 1) rock removal by exceeding its shear strength strength and 2) removal removal by b y exceeding the compressive compressive strength. strength. Broken rock is removed removed by rotary scraping or hydraulic cleaning. Drag Bits
he drag bit is the oldest rotary tool still used by the drilling drilling industry industry.. hese bits are currently currently manufactured in several different designs with various cutter blade !uantities and shapes "#ig. $% &). he cutting blades are integrally made with the bit body or are fixed to it and rotate as a unit with with the the dril drills lste tem. m. his his bit bit is used used prim primari arily ly in soft soft and and gummy gummy form format atio ions ns.. 'pti 'ptimu mum m performance is attained by arranging the hydraulic e!uipment and selecting no((le si(es so maximum available hydraulic horsepower is expended at the bit. etallurgy has played an important role in improving current bit designs over the early two%blade fishtail bit.
*ome *ome of the improv improveme ements nts causin causing g contin continued ued succes successs in certain certain soft soft format formation ionss are the following:
• • • •
Blade contour design. +roper balance of lineal contact on bottom. ,se of hard facing materials on blades. Better positioning of the watercourses use of erosion%resistant no((les.
Rolling Cutter Bits
he emergence of rolling cutter- or cone- bits has virtually eliminated the use of drag bits due to overall versatility. he rolling bit can drill all types of formations and can be altered to achieve special functions- such as directional control or coring. /n addition- technological advances have extended bit operating lives and permitted the bit to drill long formation intervals. he basic design of the rolling cutter bit consists of the body- cones- and internal flow paths to allow fluid circulation. he bit body generally consists of /) the shank- 2) bit leg"s)- and &) 0ournal pins for cone attachment. ones are the actual segments of the bit that contact the formation- causing rock failure. he cone may %have steel teeth forged as an integral part of the cone or tungsten carbide teeth inserted into the cone for increased tooth life. #low paths within the bit let the drilling fluid circulate to achieve special functions such as hole cleaning and bit cooling.
There are two types of roller cone bits:
Milled tooth bits: 3ere the cutting structure is milled from the steel making up the cone. Insert bits: he cutting structure is a series of inserts pressed into the cones. Diamond (and Diamond Blank) Bits: he use of diamond inserts in a special bit matrix is an
accepted method of drilling various formations. he diamond is embedded in the formation and dragged across the face of the rock in a plowing action. he diamond bit drills according to the shear failure mechanism and is generally limited to certain hardness formations and hole si(es. 4iamond bits will be discussed in greater detail in later sections. Rolling Cutter Bit Design
Rolling cutter bits receive predominant use throughout the world. 5s a result- an understanding of their design principles is essential for effective drilling operations. ommon designs used by most manufacturers will be discussed with a description of various special designs when applicable. 'mission of new or innovative characteristics is done for practicality until these advances have received ade!uate field testing. Bit Bodies .
he bit body consists of 1) he threaded connection- or shank which attaches the bit to the drill string2) he bearing pins on which cones are mounted&) he lubricant reservoirs- which contain the lubricant supply for the b earings- and 6) he watercourses through which the drilling fluid flows to clean the cuttings from the hole. he individual body sections- including the integral bearing pins- are machined from forgings or castings of a nickel%chromium molybdenum alloy steel of a carburi(ing grade.
he shank of the bit connects the body to the bit sub or lowermost drill collar. he top of the shank is used for identification. /t contains such information as 1) bit diameter in inches- 2) assembly number- &) type- 6) manufacturers trademark- and 7) serial number. he shank seat and shoulder provide the fluid seal between the bit and the drill string. he bit legs- when welded together- provide the structural support for the bit. he dimple is a buildup of metal to provide additional support. he lower exterior section of the bit leg is the8 shirttail.8 he bit body is forged with no((le shrouds for the 0ets in a 0et%type bit. he 0ournal pin is an integral part of the bit leg that provides the connecting point between the bit cone and the body. he angle of the 0ournal pin from the hori(ontal varies- depending on the type of the rock the bit is designed to drill. 3ard%formation bits that are generally sub0ected to high bit weights have the pin oriented so it can accept the greater vertical component of the bit load.
5nother design feature of the bearing pin is the angle between the center line of the pin and the geometric center of the bit. he offset from the center of the bit causes the cone to drag across the formation and creates additional shearing actions- termed skew. 5s harder rocks are drilledthe degree of offset for the various types of bits decreases since compressive failure becomes the primary drilling mechanism instead of shearing. oo much skew will cause the bit to wear !uickly in hard formations.
Watercourses
5n important part of a rock bit is the watercourses- without which the rest of the rock bit could not function as intended. 9ater courses are passageways for the circulating fluid- which primarily brings cuttings to the surface and cleans the formation below the bit. he design of the passage ways and no((les that direct the fluid at the bit differentiates between the two types of watercourses: 1) conventional watercourses that direct the fluid onto the cutters and 2) 0et watercourses that direct the fluid onto the bottom of the hole.
!DC bit classification for roller cone bits
/nternational 5ssociation of 4rilling ontractors "/54) established a three code system for roller cone bits" he first code or digit defines the series classification relating to the cutting structure. he first code carries the numbers 1 to . #or milled tooth bits- the first code carries the numbers 1 to &which describes soft- medium and hard "and semi%abrasive or abrasive) rocks respectively. his number actually signifies the compressive strength of rock. #or insert bits- the first code carries the numbers 6%. he second code relates to the formation hardness subdivision within each group and carries the numbers 1 to 6. hese numbers signify formation hardness- from softest to hardest within each series. he second code is a subdivision of the first code "1 to ). he third code defines the mechanical features of the bit such as non%sealed or sealed bearing. urrently there are seven subdivisions within the third code: 1. ;on%sealed roller bearing 2. Roller bearing air cooled &. *ealed roller bearing
6. *ealed roller bearing with gauge protection 7. *ealed friction bearing <. *ealed friction bearing with gauge protection $. *pecial features % category now obsolete. 5s an example- a code of 1%2%1 indicates ode 1: long- slim and widely spaced milled tooth bit ode 2: medium soft formations "if this number was 6- then it is hard soft formation) ode &: non%sealed bearings #DC BT D$%&' $$$'T%
here are many details relating to bit design which cannot all be covered in detail here. he +4 design is affected by: 1. Body design: can either be steel%bodied or tungsten carbide "matrix) 2. utters =eometry: utters ;umber of utters and spacing of cutters *i(e of utters Back Rake *ide Rake &. =eometry of Bit ;umber of Blades Blade 4epth 6. 4iamond table *ubstrate interface omposition *hape !pplications and numericals
