Steam compressor comprising a dry positive-displacement unit as a spindle compressor

Abstract

The invention relates to a spindle compressor designed as a twin-shaft rotary displacement machine for delivering and compressing flow media, particularly steam. It comprises a pair of spindle rotors in a compressor housing (1) comprising an inlet collecting space (11) and an outlet collecting space (12). The centre distance of the pair of spindle rotors is at least 10% longer on the inlet-side end than on the outlet-side end. Each of the two spindle rotors (2, 3) is driven by an electric motor (18, 19), and an electronic synchronisation controls the electric motors (18, 19) such that the spindle rotors (2, 3) rotate in a contact-free manner.

1 . A spindle compressor as a 2-shaft rotary positive-displacement machine, working without operating fluid in the working space, for conveying and compressing gaseous conveyed media, preferably steam, comprising a spindle rotor pair in a compressor housing ( 1 ) which has an inlet collection chamber ( 11 ) and an outlet collection chamber ( 12 ),
 characterised in that the centre distance of the spindle rotor pair at the inlet-side end is at least 10% greater than at the outlet-side end, in that each of the two spindle rotors ( 2 ,  3 ) is driven by an electric motor ( 18 ,  19 ), and an electronic synchronisation controls the electric motors ( 18 ,  19 ), and in that the spindle rotors ( 2 ,  3 ) rotate contact-free.   
     
     
         2 . The spindle compressor according to  claim 1 ,
 characterised in that one spindle rotor ( 2 ) has two teeth, in that the other spindle rotor ( 3 ) has three teeth, and in that the electronic synchronisation is a 2 to 3 synchronisation.   
     
     
         3 . The spindle compressor according to  claim 1 ,
 characterised in that each spindle rotor ( 2  or  3 ) has an internal cooling means, which preferably is embodied as a cylindrical evaporator cooling bore ( 6 ) of radius RC 2  on the 2-toothed spindle rotor ( 2 ) or of radius RC 3  on the 3-toothed spindle rotor ( 3 ).   
     
     
         4 . The spindle compressor according to  claim 3 ,
 characterised in that the evaporator cooling bore ( 6 ) has an inner structure with at least one of the following features, preferably more than one:   a) at least one cooling fluid guide groove ( 16 ), preferably with precise (deviation <1%) observance of the R C  value, in particular with
 a.1) groove base faces with angles of inclination ψ(z) with 170°≤ψ(z)≤180° as f(z) 
 and/or 
 a.2) the outlet region has a larger surface for heat transfer than the inlet region, 
   b) cooling fluid distribution overflow grooves ( 17 )   c) support points ( 7 ) for non-rotational support on the corresponding carrier shaft ( 4  or  5 )   d) steam outlet ( 14 ) in the inlet chamber ( 11 ).   
     
     
         5 . The spindle compressor according to  claim 1 ,
 characterised in that each spindle rotor system is embodied with the rotary unit ( 40 ) ready-assembled and balanced, and in that separator plates ( 26 ) are preferably provided for the final setting of the play between rotor heads and housing.   
     
     
         6 . The spindle compressor according to  claim 1 ,
 characterised in that at least one vibration sensor ( 39 ) is provided and is connected to a control unit ( 25 ), and in that in the control unit ( 25 ) the supplied amount of the cooling fluid flow ( 9 ) is limited to the amount corresponding to a maximisation of the overall efficacy.   
     
     
         7 . The spindle compressor according to  claim 2 ,
 characterised in that the critical bending speed of the 2-toothed spindle rotor is approximately (with a tolerance of preferably less than ±30%) 1.5 times higher than the critical bending speed of the 3-toothed spindle rotor ( 3 ).   
     
     
         8 . The spindle compressor according to  claim 1 ,
 characterised in that the crossing angle alpha between the two spindle rotor axes of rotation in combination with the corresponding μ(z) value in the rotor longitudinal axis direction is such that, for each rotor, a cylindrical evaporator cooling bore ( 6 ) with minimal (that is to say appropriate for the particular tooth height in respect of material strength) wall thicknesses w is created on the supporting root-base body ( 32 ) (for example in accordance with the aforementioned position descriptions of E, S, V and L) under simultaneous consideration of the (preferably) blowhole-free profiling of the gas-conveying external thread ( 31 ) and critical bending speed “appropriate for the specific rotor spindle” and implementation of the inner volume ratio as iV value (as explained), wherein the gas-conveying external thread ( 31 ) is formed in the inlet region as a 2-toothed spindle rotor ( 2 ) preferably with cylindrical flattened portion ( 27 ).   
     
     
         9 . The spindle compressor according to  claim 1 ,
 characterised in that the thermal situation for the working space components is regulated in an application-specific manner as basic step (as explained) during the component heat dissipation during operation to maintain the play values between avoidance of play reduction and excessive differences in the play values (as explained) and as FCT stage (as explained) during the component heat dissipation, to improve efficacy
 as diverted cooling fluid flow 
 as separate cooling water flow 
 via delayed evaporation 
   with cooling fluid injection ( 33 ) into the compressor working space, preferably in the region of the inlet collection chamber ( 11 ), which is all regulated and controlled by the control unit ( 25 ).   
     
     
         10 . The spindle compressor according to  claim 1 ,
 characterised in that each spindle rotor ( 2 ,  3 ) consists of an aluminium alloy and is pressed on to a steel shaft ( 4 ,  5 ) at the support points ( 7 ) for conjoint rotation, and in that the gas-conveying external thread ( 31 ) is only then produced and the spindle rotor ( 2 ,  3 ) has an inner structure that is already completed.   
     
     
         11 . The spindle compressor according to  claim 1 ,
 characterised in that the inner volume ratio is adapted to the current operating conditions via additional partial outlet openings ( 15 ).   
     
     
         12 . The spindle compressor according to  claim 1 ,
 characterised in that a steam outlet ( 14 ) directly to the inlet is provided.   
     
     
         13 . The spindle compressor according  claim 1 ,
 characterised in that a cylindrical flattened portion ( 27 ) is provided at the inlet of the 2-toothed spindle rotor, in particular in that the gas-conveying external thread ( 31 ) in the case of the 2-toothed spindle rotor ( 2 ) has the cylindrical flattened portion ( 27 ) in the inlet region.   
     
     
         14 . The spindle compressor according  claim 1 ,
 characterised in that the 2-toothed spindle rotor ( 2 ) is provided with an intermediate support, whereby a weight reduction, in particular also for a lower moment of inertia during start-up (or braking) alongside high flexural rigidity, is preferably achieved for example from fibre-composite material suitable for vacuum, for example in the form of a CFRP material.   
     
     
         15 . The spindle compressor according to  claim 1 ,
 characterised in that at least one cooling fluid feed ( 9 . 2  and  9 . 3 ) is provided, and in that each spindle rotor has a cylindrical evaporator cooling bore ( 6 ), which is connected to the cooling fluid feed ( 9 . 2  and  9 . 3 ).   
     
     
         16 . The spindle compressor according to  claim 1 ,
 characterised in that each drive has a hollow shaft, in that the cooling fluid feed ( 9 . 2  and  9 . 3 ) to the cylindrical evaporator cooling bore ( 6 ) of a drive is provided through this hollow shaft, and in that the bearings ( 10 ) are preferably formed as durable bearings, in particular grease-lubricated-for life hybrid bearings, all-ceramic bearings, or also magnetic bearings.