US3480199A - Capacity control system for compressor units - Google Patents

Capacity control system for compressor units Download PDF

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Publication number
US3480199A
US3480199A US685553A US3480199DA US3480199A US 3480199 A US3480199 A US 3480199A US 685553 A US685553 A US 685553A US 3480199D A US3480199D A US 3480199DA US 3480199 A US3480199 A US 3480199A
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United States
Prior art keywords
control
stage
compressor
line
control system
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Expired - Lifetime
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US685553A
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English (en)
Inventor
Friedrich Bauer
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Hoerbiger Ventilwerke GmbH and Co KG
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Hoerbiger Ventilwerke GmbH and Co KG
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F04D27/0207—Surge control by bleeding, bypassing or recycling fluids

Definitions

  • a capacity control system for multi-stage compressor units comprising control means for altering the delivery of the first-stage compressor of the unit and additional control means for altering the delivery of one of the subsequent compression stages.
  • This invention relates to a capacity control system for a compressor unit having a first-stage compressor followed by at least one subsequent compression stage, and connecting line between the compression stages.
  • Compressor units are generally required to provide adaptation of the quantity delivered to the actual needs of the consuming unit or to the volume of gas produced so as to keep the suction, the final or an intermediate pressure at a constant level.
  • the control systems used for this purpose are supposed to operate at low cost and possibly without any power losses and to offer the required degree of operational safety.
  • Conventional systems wherein all compression stages are provided with individual regulators, such as for example, with lifting devices for the suction valves operate at negligible power losses.
  • the structural expense involved is comparatively high. Consequently, in many cases only the first compression stage of a multi-stage compressor unit is subject to control whereas the higher compression stages remain uncontrolled, their deliveries diminishing only as a result of a corresponding decrease of the intermediate pressures.
  • the final pressure of a mnlti-stage compressor unit is to be kept at a constant level by controlling the delivery of the first compression stage only, the resulting lower periods being frequently of great length due to the slow alteration of individual intermediate pressures. Consequently, the compressor assembly will respond to each control pulse by altering the delivery of the last stage after a considerable delay only. Therefore, unless the alterations are very slow, oscillations are liable to occur running through the entire control circuit. In many cases stability may be maintained by the use of regulators featuring a specific time behaviour. This is, however, possible only at the expense of the quality of control, such operating conditions as the control system is meant to ensure, cannot as a rule, be maintained for any length of time within the desired limits.
  • the invention provides for a capacity control system for a compressor unit having a first-stage compressor fol- Patented Nov. 25, 1969 lowed by at least one subsequent compression stage, and connecting lines between the compression stages, comprising control means for altering the delivery of the first-stage compressor and additional control means for altering the delivery of at least one of the subsequent compression stages, the said first control means being adjusted as required by control pulses, said additional control means being temporarily adjusted for a brief period of time only dependent on a change in a physical condition prevailing in the connecting line between two preceding compression stages thereby altering the delivery of the said subsequent compression stage and reducing the time required by a control pulse released to the first-stage compressor controlling the means for altering the delivery of the first-stage compressor, for its passage through the entire compressor unit.
  • control system assures permanent maintenance, with a high degree of precision, of the operating condition required at the end of the control range, such as for example, of the final pressure of the compressor unit, within narrow limits.
  • the last compression stage of the compressor unit is provided with said additional control means for altering the quantity delivered.
  • the additional control means may be controlled as a function of a physical condition, preferably of pressure, in the connecting line between the first-stage compressor and the adjacent compression stage. All or part of the compression stages may consist of piston-type compressors.
  • the temporarily acting additional control means for altering the delivery of one of the subsequent compression stages may be operated according to any control system. Since in normal operation the compressor unit is controlled by means of the control means acting upon the first-stage compressor only and the additional control means are in operation only temporarily, a power loss-involving method can be used for the purpose without perceptibly impairing the efficiency of the whole system.
  • the additional temporary control means in a simple manner may comprise a control line branching off the delivery side of the said subsequent compression stage, a throttle valve inserted in the control line for the purpose of altering its cross-sectional area, and a control device liable to be influenced by a physical condition prevailing in the connecting line between two compression stages and controlling the said throttle valve.
  • the control line may terminate into the atmosphere or return at any convenient point to the connecting line between two compression stages, preferably to the connecting line by which the associated control device is impinged upon, such as for example, to the connecting line between two compression stages, thereby forming a by-pass.
  • FIGURE 1 is a schematic view of a three-stage compressor unit for the purpose of explaining the control system according to the invention.
  • FIGURE 2 is a schematic illustration of a compressor unit comprising four compression stages and equipped with a control system according to the invention.
  • the individual compression stages are designated by reference numbers I to IV, stage I defining the first-stage compressor and the remaining stages II to IV the subsequent compression stages following the first-stage compressor.
  • a suction pipe 1 terminates in the first-stage compressor I, connecting lines 2 are provided between individual compressor stages and the consumption pipe 3 emerges from the last compression stage.
  • a control pulse is released to the first-stage compressor I via a control line 4, the effect of the said pulse being a decrease of the quantity delivered by the first-stage compressor I into the adjacent connecting line 2.
  • the intermediate pressure in the connecting line 2 drops and so does the suction pressure of the second compression stage II, thereby decreasing also the quantity delivered by that stage accordingly.
  • the suction pressure of the third compression stage II will then drop with a retardation of the second order and so will the quantity delivered by the compression stage II, and finally the control pulse released to the first-stage compressor I will become effective in the consumption line 3 with a retardation of the third order.
  • the quantity delivered by the compression stage III is temporarily altered in accordance with the control pulse as a function of the intermediate pressure prevailing in the connecting line 2 emerging from the first-stage compressor I.
  • a control device R is provided which is connected to the connecting line 2 via a line 5 and releases a control pulse to the compression stage III via a control line 6.
  • the retardation due to the passage of the control pulse through the compressor unit in the compression stage II is thus eliminated so that the down time of the compressor unit is correspondingly reduced.
  • the reaction velocity of the control system is thereby increased to a considerable extent. This feature is particularly important for compressor units comprising a plurality of compression stages.
  • the first-stage compressor 1 such as a double-acting piston-type compressor
  • a lifting mechanism 7 for the suction valves on each side of the cylinder which are controlled in accordance with the stroke rhythm by means of a main control device R via a control line 4.
  • the control device R is impinged upon by the final pressure of the compressor unit prevailing in a pressure tank 9 interpolated between the last compression stage IV and the consumption line 3, and serves to keep the said final pressure at a constant level.
  • the control device R is fed via a feed pipe 10.
  • the higher compression stages II to IV are by-passed by a by-pass line 11 emerging from the delivery pipe 12 of the last compression stage IV terminating in the pressure tank 9, the said by-pass line 11 terminating in the connecting line 2 between the first stage compressor I and the compression stage II.
  • An intermediate cooler 13 and a liquid draining device 14 are interpolated in each of the connecting lines 2 between individual compression stages and in the delivery pipe 12.
  • the by-pass line 11 is controlled by means of an infinitely variable throttle valve 15 actuated via a control line 16 by means of a control device R which is in turn controlled via line 5 as a function of the intermediate pressure between the compression stages I and II.
  • the control device R and the throttle valve 15 are fed via a feed line 17 having incorporated an adjustable throttle valve 18.
  • the control device R may for example, be a diaphragm governor comprising -a retarding throttle 19 and altering the pressure in the control line 16 when the intermediate pressure in the connecting line 2 drops, as a result of which the throttle valve 15 opens, allowing the compressed medium to flow from the delivery pipe 12 via the bypass line 11 back into the connecting line 2 between the compression stages I and II.
  • the pressure difference acting upon the control device R is reduced by means of the retarding throttle 19, so that the former slowly returns to its original position, thereby closing the throttle valve 15.
  • the retarding throttle 19 the closing velocity can be adapted to compensate the lack of reactivity of the higher compression stages II to IV in such a manner that no oscillations will occur in the pressure tank 9.
  • the diaphragm governor R has an initial tendency to keep the intermediate pressure between the compression stages I and II at an approximately constant level, as a result of which precisely the excess quantity of the pressure medium is blown from the delivery pipe 12 into the connection line 2 forming the suction pipe of the compression stage II and causes a slow transition from the by-pass control to the nondissipative capacity control by means of reduced intermediate pressures, without influencing the final pressure in the process.
  • the reaction velocity of the compressor unit control system is substantially increased by means of the additional temporary control mechanism. Since the by-pass control is operative only temporarily for brief intervals following sudden major changes in consumption, the resulting loss of power is negligible.
  • the control system according to the invention is generally suitable for use in conjunction with any compressor unit control involving the problem of influencing the physical condition at one or several points of the compressor unit by means of a control pulse released to the first-stage compressor.
  • the reaction velocity of the control system is considerably increased by the reduction of the time required for the passage of the control pulse through the entire compressor unit, so that objectionable oscillations and overriding are avoided and maintenance of the desired operational condition is assured within narrow limits.
  • a capacity control system comprising control means for the first-stage compressor and additional control means for at least one of the subsequent compression stages, the first control means being controlled by control signals, a control device for the additional control means and initiated by a change in a physical condition prevailing in the connecting line between two preceding compression stages, and adjustable regulator means for limiting the working time of the control device, the said additional control means being temporarily in working condition for a brief period of time only, altering the delivery of the said subsequent compression stage and reducing the time required for the passage through the entire compressor unit of a control signal released to the first-stage compressor.
  • the compressor unit comprises a first-stage compressor and at least two subsequent compression stages, the said additional control means controlling the last compression stage.
  • the compressor unit comprises a first-stage compressor and at least two subsequent compression stages
  • the said additional control means controlling the last compression stage, being controlled as a function of a physical condition prevailing in the connecting line between the firststage compressor and the adjacent compression stage.
  • the additional control means for altering the delivery of at least one of the subsequent compression stages comprising a control line branching off the delivery side of the controlled subsequent compression stage, a throttle valve being provided inserted in the control line for the purpose of altering its cross-sectional area and controlled by the said control device liable to be influenced by a physical condition prevailing in the connecting line between two compression stages, the control line forming a by-pass connecting the delivery side of the controlled subsequent compression stage with the connecting line between two preceding compression stages.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Control Of Positive-Displacement Air Blowers (AREA)
US685553A 1966-11-24 1967-11-24 Capacity control system for compressor units Expired - Lifetime US3480199A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT1086666A AT276612B (de) 1966-11-24 1966-11-24 Steuerung für eine Verdichteranlage

Publications (1)

Publication Number Publication Date
US3480199A true US3480199A (en) 1969-11-25

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US685553A Expired - Lifetime US3480199A (en) 1966-11-24 1967-11-24 Capacity control system for compressor units

Country Status (5)

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US (1) US3480199A (de)
AT (1) AT276612B (de)
DE (1) DE1628165C3 (de)
FR (1) FR1554797A (de)
GB (1) GB1211741A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120230840A1 (en) * 2009-11-12 2012-09-13 Rolls-Royce Plc Gas compression

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE384871T1 (de) † 2004-10-19 2008-02-15 Voith Patent Gmbh Mehrstufiger kolbenverdichter mit reduzierter leistungsaufnahme im leerlauf
FR2898645B1 (fr) * 2006-03-14 2008-08-22 L'air Liquide Compresseur a plusieurs etages, appareil de separation d'air comprenant un tel compresseur et installation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US858470A (en) * 1904-11-19 1907-07-02 Walter J Richards Fluid-pressure system.
US1759617A (en) * 1927-08-27 1930-05-20 Firm Hoerbiger & Co Gas compressor
US1863845A (en) * 1929-04-22 1932-06-21 Sullivan Machinery Co Fluid compressor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US858470A (en) * 1904-11-19 1907-07-02 Walter J Richards Fluid-pressure system.
US1759617A (en) * 1927-08-27 1930-05-20 Firm Hoerbiger & Co Gas compressor
US1863845A (en) * 1929-04-22 1932-06-21 Sullivan Machinery Co Fluid compressor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120230840A1 (en) * 2009-11-12 2012-09-13 Rolls-Royce Plc Gas compression
US9022747B2 (en) * 2009-11-12 2015-05-05 Rolls-Royce Plc Gas compression

Also Published As

Publication number Publication date
FR1554797A (de) 1969-01-24
DE1628165B2 (de) 1978-05-03
DE1628165A1 (de) 1972-01-13
AT276612B (de) 1969-11-25
DE1628165C3 (de) 1978-12-21
GB1211741A (en) 1970-11-11

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