# US 2014/0154051 A1 · Antisurge pretection method for centrifugal compressors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154051 A1 - Document ID: US20140154051A1 - Status: Published application - Kind: A1 - Application number: 14/232,896 - Filed: 2012-06-25 - Published: 2014-06-05 - Earliest claimed: 2011-07-07 - Assignees: Industrial Plants Consultants Srl - Applicants: Industrial Plants Consultants Srl - Inventors: Massimiliano Di Febo; Antonio Di Febo - Web page: https://patentgrep.com/patent/US20140154051A1 ## CPC - F04D 27/001: {Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring} - F04D 27/02: Surge control {(surge detection F04D27/001)} - F04D 27/009: {by bleeding, by passing or recycling fluid} - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) ## Abstract Method for individuating the pumping conditions of the centrifugal blowers according to thermo-dynamic conditions (pressure and temperature) and to the gas composition in inlet, comprising the steps of: acquisition of the suction pressure, the suction temperature, the delivery pressure, the delivery temperature, the flow rate, the revolution number and the chemical composition of the gas mixture; calculation of the reduced conditions of the processed gaseous mixture by means of mixing equations; solution of the state equation of the real gases for the calculation of the thermo not dynamic properties of the gas mixture in the current conditions; acquisition of the performance non-dimensional curves of the blower, which express the value of the working coefficient of the blower and of the plytropic yield of the blower; calculation of the blower performance curves on the basis of the non-dimensional curves and according to the blower inlet parameters; determination of the pumping points, individuated as maximum points of the blower performance curves which express the value of the pressure in outlet according to the sucked flow rate. ## Claims ### Claim 1 Method for individuating the pumping conditions of centrifugal blowers according to the thermodynamic conditions (pressure and temperature) and to the gas composition in inlet, comprising the steps of: a) acquisition of the suction pressure (pi), the suction temperature (TI), acquisition of the delivery pressure (p2), the delivery temperature (T2), the flow rate (Q), the revolution number (n) and of information about the chemical composition of the gas mixture in inlet at the blower (1); b) calculation of the reduced conditions of the processed gaseous mixture by means of mixing equations; c) solution of the state equation of the real gases for the calculation of the thermo-dynamic properties of the gas mixture in the current conditions acquired at the previous point (a). d) acquisition of the performance non-dimensional curves of the blower, which express the value of the blower working coefficient and of the polytropic yield of the blower, according to the Mach number in inlet and to the flow rate parameter; e) calculation of the blower performance curves which express the value of pressure and temperature in outlet (2, T2) and of the polytropic predominance {Hp) according to the flow rate and. the revolution number, on the basis of said performance non-dimensional curves acquired at point d), and according to the blower inlet parameters acquired at point a) f) determination of the pumping points, individuated as maximum points of the blower performance curves which express the value of the pressure in outlet according to the sucked flow rate, and according to the variation of the revolution number. ### Claim 2 (depends on 1) Method for individuating the pumping conditions of centrifugal blowers according to claim 1, wherein said calculation of the reduced conditions of the gas mixture at the blower inlet is carried out by applying the “mixing rules” of Kay, modified by Lee-Kesler and Plock, Knapp, Prausnitz et al. (1978). ### Claim 3 (depends on 1) Method for individuating the pumping conditions of centrifugal blowers according to claim 1, wherein said thermo-dynamic properties of the mixture calculated at point c) comprise the following ones: Polytropic volume exponent n v = - v p  ( ∂ p ∂ v ) η p polytropic temperature exponent n T = 1 1 - p T  ( ∂ T ∂ p ) η p isentropic volume exponent k v = - v p  ( ∂ p ∂ v ) s Gas molar constant R=R/M Gas compressibility factor (z) p·v=z·R·T. ### Claim 4 (depends on 3) Method for individuating the pumping conditions of centrifugal blowers according to claim 3, wherein said thermo-dynamic properties are calculated using a state equation of real gases, preferably between the following ones: LK (lee-Kesler), PR (Peng Robinson), RKS (Redlich-Kwong, Soave), BWRS (Benedict-Webb-Rubin-Starling), for example the state equation of Lee Kesler (B. I. Lee, M. G. Kesler. “A generalized thermo-dynamic correlation based on three-parameter corresponding states”, AiChE Journal 1975, 21 (3), 510-527).  Z = Z ( 0 )  ( T r , P r ) + ω   Z ( 1 )  ( T r , P r ) ,  Z = ( P r  V r T r ) = 1 + f 1  ( T r ) V r + f 2  ( T r ) V r 2 + f 3  ( T r ) V r n + f 4  ( T r )  [ ( a + γ V r 2 )  1 V r m ]  exp  ( - γ V r 2 ) , ƒ1÷4, ∝, are functions and constants described in the reported references. ### Claim 5 (depends on 1) Method for individuating the pumping conditions of centrifugal blowers according to claim 1, wherein said calculation of the blower performance curves which express the value of pressure and temperature in outlet, and the polytropic predominance, in function of the flow rate and the revolution number is carried out, with the curves known, ηp=f(φ,Mu), ηpτf(φ,Mu) known, with M u = u 2 k v   1 · z 1 · R · T 1  ϕ = 4 π · Q d 2 2 · u 2  u 2 = π   nd 2 60 according to the following calculation steps: Hp = η p  τ · u 2 2 a ) β = [ 1 + H p z 1  RT 1 · n V - 1 n V ] b ) p 2 = p 1 · β . c ) T 2 = T 1 · β n T - 1 n T . d ) ### Claim 6 (depends on 1) Method for the protection of the centrifugal blowers against the pumping phenomenon comprising the steps of: A) measuring the flow rate processed by the blower (Q), the pressure and temperature of the gas in the inlet section (pi, TI), the revolution number (n) and acquisition of the chemical composition of the gas in inlet; B) individuating the blower pumping flow rate in the effective functioning conditions, by applying the method according to claim 1; C) comparing the individuated pumping flow rate at point B with the processed flow rate individuated at point A, and, in case the difference is lower than a predetermined safety margin, total or partial opening of a gas recirculation valve (2) from the suction delivery. ### Claim 7 (depends on 1) Method for providing diagnostic signals in order to detect problems of flow rate measurement in the centrifugal blowers, or problems of mechanic or instrumental type, to be used with the method for individuating the pumping conditions according to claim 1, comprising the following steps: Calculating the expected delivery pressure (p2EXP) and of the expected delivery temperature (T2EXP); Detecting if the expected delivery pressure (p2EXP) is different from the measured delivery pressure (p2MEAB), and/or the expected delivery temperature (T2EXP) is different from the measured delivery temperature (T2MEAB), then (p2EXP≠p2MEAB or T2EXP≠T2MEAB) Calculating the expected flow rate according to the measured delivery pressure (QEXP@P2MEAB) by means of dimensional performance maps of the blower, upgraded to the current inlet conditions according to the method of claim 1; Calculating the expected flow rate according to the measured delivery temperature (QEXP@T2MEAB) by means of dimensional performance maps of the blower, upgraded to the current inlet conditions according to the method of claim 1. If QEXP@P2MEAB=QEXP@P2MEAB then (D2) providing a diagnostic signal concerning the measure equipment of the flow rate and indicating an instrumental problem about the flow rate reading; Substituting the flow rate acquired at point a) of claim 1 with the expected flow rate according to the measured delivery pressure (QEXP@P2MEAB) Otherwise (QEXP@P2MEAB≠QEXP@P2MEAB) If QEXP@P2MEAB>QEXP@T2MEAB then (D3) diagnostic signal indicating a mechanic problem on the blower, i.e. a reduction in the polytropic yield. Otherwise (QEXP@P2MEAB