Expander lubrication in vapour power systems

Abstract

A vapour power generating system including a closed circuit for a working fluid, and includes a heat exchanger assembly for heating the fluid under pressure with heat from the source, a separator for separating the vapour phase of the heated fluid from the liquid phase thereof, an expander for expanding the vapour to generate power, a condenser for condensing the outlet fluid from the expander, a feed pump for returning condensed fluid from the condenser to the heater and a return path for returning the liquid phase from the separator to the heater. The liquid phase of the working fluid contains a lubricant which lubricant is soluble or miscible in the liquid phase and a bearing supply path is arranged to deliver liquid phase pressurised by the feed pump to at least one bearing for a rotary element of the expander.

1 . A closed circuit vapor power generator system comprising:
 A. a closed circuit;   B. a working fluid in the closed circuit, the working fluid comprising a vapor phase, a liquid phase, and a lubricant soluble or miscible in the liquid phase;   C. a working fluid heater in the closed circuit;   D. a heat source in communication with the working fluid heater;   E. a separator in the closed circuit in communication with the working fluid heater;   F. an expander in the closed circuit in communication with the separator;   G. a condenser in the closed circuit in communication with the expander;   H. a working fluid feed pump in the closed circuit in communication with the working fluid heater;   I. a working fluid return path in the closed circuit from the separator to the working fluid heater; and   J. a bearing lubricant supply path in the closed circuit from the working fluid feed pump to at least one bearing element for at least one rotary element of the expander.   
     
     
         2 . The closed circuit vapor power generator system of  claim 1  wherein:
 (i) the heat source is in heating communication with the working fluid heater; 
 (ii) the separator is in working fluid transfer communication with the working fluid heater; 
 (iii) the expander is in working fluid transfer communication with the separator; 
 (iv) the condenser is in working fluid transfer communication with the expander; and 
 (v) the working fluid feed pump is in working fluid communication with the working fluid heater. 
 
     
     
         3 . The closed circuit vapor power generator system of  claim 1  wherein the working fluid heater includes an evaporator section and a heater section, and the working fluid return path leads to a junction between the working fluid heater and the evaporator section. 
     
     
         4 . The closed circuit vapor power generator system of  claim 1  wherein collection spaces are in communication with the at least one bearing element. 
     
     
         5 . The closed circuit vapor power generator system of  claim 1  wherein the bearing lubrication supply path includes a working fluid cooling heat exchanger. 
     
     
         6 . The closed circuit vapor power generator system of  claim 1  wherein the expander is a rotary expander. 
     
     
         7 . The closed circuit vapor power generator system of  claim 2  wherein the expander is a rotary expander. 
     
     
         8 . The closed circuit vapor power generator system of  claim 6  wherein the expander includes two rotary expander screws. 
     
     
         9 . The closed circuit vapor power generator system of  claim 7  wherein the expander includes two rotary expander screws. 
     
     
         10 . The closed circuit vapor power generator system of  claim 8  wherein the bearing fluid supply path leads to the at least one bearing element for a first rotary screw and the at least one second bearing element for a second rotary screw. 
     
     
         11 . The closed circuit vapor power generator system of  claim 1  wherein a liquid phase receiver is in communication with the condenser and the feed pump. 
     
     
         12 . The closed circuit vapor power generator system of  claim 2  wherein a liquid phase receiver is in working fluid transfer communication with the condenser and the feed pump. 
     
     
         13 . The closed circuit vapor power generator system of  claim 1  wherein the heat source comprises a source of moderate or low grade heat. 
     
     
         14 . The closed circuit vapor power generator system of  claim 1  wherein the heat source includes an internal combustion engine. 
     
     
         15 . The closed circuit vapor power generator system of  claim 1  wherein the working fluid includes an organic fluid. 
     
     
         16 . The closed circuit vapor power generator system of  claim 1  wherein the working fluid includes chlorotetrafluoroethane, tetrafluroethane, pentafluoropropane, or light hydrocarbons such as isoButane, n-Butane, isopentane, or n-Pentane. 
     
     
         17 . The closed circuit vapor power generator system of  claim 1  wherein the at least one bearing element for the at least one rotary element of the expander is a heat generating bearing, whereby the at least one rotary element of the expander evaporates liquid phase of the working fluid. 
     
     
         18 . The closed circuit vapor power generator system of  claim 1  wherein the working fluid heater includes a single pass boiler. 
     
     
         19 . The closed circuit vapor power generator system of  claim 1  wherein working fluid heater is in heating communication with an internal combustion engine and the working fluid includes an organic working fluid. 
     
     
         20 . The closed circuit vapor power generator system of  claim 1  wherein a percentage by weight of lubricant is up to 5% of a weight of the working fluid. 
     
     
         21 . The closed circuit vapor power generator system of  claim 1  wherein the percentage by weight of lubricant is 0.5 to 2% of the weight of the working fluid. 
     
     
         22 . The closed circuit vapor power generator system of  claim 2  wherein a percentage by weight of lubricant is up to 5% of a weight of the working fluid. 
     
     
         23 . The closed circuit vapor power generator system of  claim 2  wherein the percentage by weight of lubricant is 0.5 to 2% of the weight of the working fluid. 
     
     
         24 . A closed flow circuit vapor power generating system comprising:
 A. a closed flow mixed lubricant-working fluid circuit;   B. a mixed lubricant-working fluid heater in the closed flow mixed lubricant-working fluid circuit;   C. an expander having an expander support structure and being in the closed flow mixed lubricant-working fluid circuit in flow communication with the mixed lubricant-working fluid heater;   D. a condenser in the mixed lubricant-working fluid closed flow circuit in flow communication with the expander;   E. a working fluid feed pump in the closed flow mixed lubricant-working fluid circuit in flow communication with the condenser and the mixed lubricant-working fluid heater; and   F. a mixed lubricant-working fluid supply path in the closed flow mixed lubricant-working fluid circuit in flow communication from the working fluid working fluid feed pump to the expander support structure.   
     
     
         25 . The closed flow circuit vapor power generating system of  claim 24  wherein:
 (i) the expander includes a first screw and a second screw, the first screw supported by a first screw support structure and the second screw supported by a second screw support structure; and 
 (ii) the mixed lubricant-working fluid supply path is in flow communication from the working fluid feed pump to the first screw support structure and second screw support structure. 
 
     
     
         26 . The closed flow circuit vapor power generating system of  claim 24  wherein the mixed lubricant-working fluid heater comprises a source of moderate or low grade heat. 
     
     
         27 . The closed flow circuit vapor power generating system of  claim 26  wherein the mixed lubricant-working fluid heater includes a single pass boiler. 
     
     
         28 . The closed flow circuit vapor power generating system of  claim 24  wherein the expander support structure includes a screw expander bearing in lubricating communication with the working fluid feed pump. 
     
     
         29 . The closed flow circuit vapor power generating system of  claim 24  wherein the source of heat is in heating communication with an internal combustion engine and the working fluid includes an organic working fluid. 
     
     
         30 . The closed flow circuit vapor power generating system of  claim 24  further comprising a mixed lubricant-working fluid including a liquid phase, a vapor phase, and a lubricant miscible with or soluble in the liquid phase, and wherein a percentage by weight of the lubricant in the liquid phase is up to 5% of a weight of the mixed lubricant-working fluid. 
     
     
         31 . The closed flow circuit vapor power generating system of  claim 24  wherein the percentage by weight of lubricant is 0.5 to 2% of the weight of the working fluid. 
     
     
         32 . A vapor power generating system comprising:
 A. a closed circuit with a lubricating working fluid;   B. a pressurized lubricating working fluid heater in the closed circuit;   C. a heat source in communication with the pressurized lubricating working fluid heater;   D. a separator in the closed circuit in communication with the pressurized lubricating working fluid heater;   E. a power generating expander in the closed circuit in communication with the separator;   F. a working fluid condenser in the closed circuit in communication with the power generating expander;   G. a working fluid feed pump in the closed circuit in communication with the working fluid condenser and the pressurized lubricating working fluid heater;   H. a working fluid return path in the closed circuit from the separator to the pressurized lubricating working fluid heater;   I. a working fluid bearing supply path in the closed circuit from the working fluid feed pump to at least one bearing section for at least one rotary element of the power generating vapor phase expander; and   J. a condenser in the working fluid bearing supply path.   
     
     
         33 . The vapor power generating system of  claim 32  further comprising a working fluid in the closed circuit and having a vapor phase, a liquid phase, and a lubricant mixed with the liquid phase. 
     
     
         34 . The vapor power generating system of  claim 32 , wherein the percentage by weight of the lubricant in the liquid phase of the lubricating working fluid is less than or equal to 5% of a weight of the working fluid. 
     
     
         35 . The vapor power generating system of  claim 32  wherein the percentage by weight of the lubricant in the liquid phase of the lubricating working fluid is 0.5 to 2% of the weight of the working fluid.