Waste-heat recovery system

Abstract

A waste recovery system for a waste-heat source made up of an ORC (Organic-Rankine Cycle) postconnected thereto is described. The waste-heat source is in connection with the heating device of the ORC as well as with an expansion machine for steam expansion in the ORC coupled to a generator. The design and operating behavior of a force-heat coupling system is optimized, a waste-heat recovery system made up of an ORC post-connected to a waste-heat source. The expansion machine for steam expansion in the ORC is therefore started up by the generator which is operating in motor mode, and brought to a minimum starting engine speed able to be specified in a control device.

1 - 11 . (canceled) 
     
     
         12 . A waste-heat recovery system for a waste heat source, comprising:
 an ORC (Organic Rankine Cycle) postconnected to the waste heat source, the waste heat source being connected to a heating device of the ORC;   a generator;   a control device; and   an expansion machine, coupled to the generator, for a steam expansion in the ORC, wherein the expansion machine is run up by the generator operating in engine mode and is brought to a minimum starting engine speed specifiable in the control device.   
     
     
         13 . The waste-heat recovery system as recited in  claim 12 , wherein the minimum starting engine speed corresponds to approximately two thirds of a minimum operating engine speed. 
     
     
         14 . The waste-heat recovery system as recited in  claim 12 , wherein:
 when a minimum starting speed has been reached, a steam valve at an intake of the expansion machine is opened, and   during a further opening of the steam valve, a further run-up of an engine speed takes place and the generator transitions from motor-actuated operation to normal generator operation.   
     
     
         15 . The waste-heat recovery system as recited in  claim 14 , wherein a process for optimizing an engine speed is enabled in the control device when the steam valve is completely open and a minimum operating engine speed has been reached. 
     
     
         16 . The waste-heat recovery system as recited in  claim 12 , wherein:
 the control device ascertains an optimum engine speed for a current operating point in that, starting from a minimum engine speed, a slow runup takes place in a first step while analyzing a generator output, the waste-heat recovery system further comprising:   an arrangement for detecting an exceeding of a nadir at a rising engine speed and simultaneously dropping generator output; and   an arrangement for reducing an engine speed, wherein the detecting and the reducing are repeated until the engine speed stabilizes at a point of maximum generator output.   
     
     
         17 . The waste-heat recovery system as recited in  claim 12 , further comprising:
 an arrangement for specifying an optimum engine speed for a current operating point via a characteristics map in the control device.   
     
     
         18 . The waste-heat recovery system as recited in  claim 12 , further comprising:
 an arrangement for assigning at least one of an input pressure and an output pressure at the expansion machine to an optimum engine speed in a characteristics map;   an arrangement for, in order to ascertain a current operating state, measuring, analyzing, and correcting a current value for the at least one of an input pressure and an output pressure at the expansion machine in the control device via the characteristics map so as to adjust an engine speed on the basis of a current value for the at least one of the input pressure and the output pressure at the expansion machine   
     
     
         19 . The waste-heat recovery system as recited in  claim 12 , further comprising:
 an arrangement for assigning at least one of an intake temperature and an exit temperature at the expansion machine to an optimum engine speed in a characteristics map; and   an arrangement for, in order to ascertain a current operating state, measuring, analyzing, and correcting a current value of the at least one of the intake temperature and the exit temperature at the expansion machine in the control device via a characteristics map so as to adjust an engine speed on the basis of a current value for the at least one of the intake temperature and the exit temperature at the expansion machine.   
     
     
         20 . The waste-heat recovery system as recited in  claim 12 , wherein:
 the generator is integrated with the expansion machine for steam expansion in the ORC, and   the generator includes a coupled frequency converter for an operation at variable engine speeds.   
     
     
         21 . The waste-heat recovery system as recited in  claim 12 , further comprising:
 a controlled bypass including at least one throttle valve provided around the expansion machine in the ORC.   
     
     
         22 . The waste-heat recovery system as recited  claim 21 , wherein:
 the controlled bypass around the expansion machine is initially open in a start-up phase, and   the controlled bypass around the expansion machine is closed when the ORC has reached a specifiable temperature level.