JP2007270622A - Internal combustion engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine system advantageous to improve durability, reliability and economic efficiency. <P>SOLUTION: This internal combustion engine system 10 has compression spaces 51 and 52 moving compression pistons 41 and 42 and compressing gas, expansion chambers 53 and 54 moving expansion pistons 43 and 44 and burning and expanding the gas from the compression spaces 51 and 52, a fuel source 60 of fuel burnt by the expansion chambers 53 and 54, an output shaft 49 functionally connected to the expansion pistons 43 and 44, a heat exchanger 18 exchanging heat between the gas from the compression spaces 51 and 52 and exhaust gas from the expansion chambers 53 and 54, and a generator 20 arranged between the expansion chambers 53 and 54 and the heat exchanger 18 and driven by the exhaust gas from the expansion chambers 53 and 54. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine system.

  As an engine system for power generation, a gas engine system manufactured by Wartsila is known. The power generation efficiency is about 44.8% (LHV) and 41.6% (HHV). In this engine system, gas fuel preloaded by a supercharger is introduced into a four-stroke cycle engine.

As another power generation engine system, there is an engine system in which a suction / compression process and a combustion / expansion process are performed in different cylinders (see, for example, Patent Document 1). In this split engine system, attempts have been made to apply isothermal gas compression by spraying coolant and applying a regeneration cycle.
Japanese Patent No. 3544377

  In the above split engine system, the entire system including the preload supercharger has a high temperature level. In particular, the maximum gas temperature in the regenerative heat exchanger is 700 ° C. or higher. Therefore, the cost concerning the heat resistance specification of the apparatus including the regenerative heat exchanger is high. In addition, there are many technical issues to be addressed in terms of durability and reliability, such as high temperature lubrication technology, high heat resistant valve technology, and high temperature fuel supply technology.

  An object of the present invention is to provide an internal combustion engine system that is advantageous in improving durability, reliability, and economy.

  An internal combustion engine system of the present invention includes a compression chamber in which a compression piston moves and a gas is compressed, an expansion chamber in which an expansion piston moves and the gas from the compression chamber is combusted and expanded, and the expansion chamber. A fuel source for burning fuel; an output shaft operatively connected to the expansion piston; a heat exchanger for exchanging heat between the gas from the compression chamber and the exhaust gas from the expansion chamber; the expansion chamber; And a generator that is disposed between the heat exchanger and driven by exhaust gas from the expansion chamber.

  According to this internal combustion engine system, since the compression chamber and the expansion chamber are separated, the suction / compression process and the combustion / expansion process are performed by different cylinders. This is advantageous for reducing the temperature of the compressed gas in addition to reducing the compression power. Moreover, as a result of a part of the energy of the exhaust gas being recovered by the generator before the heat exchanger, the temperature level of the heat exchanger is lowered. By lowering the temperature level of the entire system, the use of high-temperature heat-resistant materials and the high-temperature design are eased, and the durability, reliability and economic efficiency of the engine system are improved.

  In the internal combustion engine system, the temperature of the gas from the compression chamber heated by the heat exchanger can be lower than the minimum ignition temperature of the fuel.

  In the internal combustion engine system, the fuel source can be fluidly connected to the compression chamber.

  In one specific example, the apparatus may further include a steam generation device that generates steam using heat generated by compression and / or combustion of the gas.

  In this specific example, the steam generator can be configured to mix at least part of the steam into the exhaust gas from the expansion chamber.

  In another specific example, a liquid supply device that blows a liquid that suppresses a temperature rise of the gas to the gas in the compression chamber can be provided.

  FIG. 1 is a schematic diagram of an engine system 10 having features of the present invention. The engine system 10 includes an internal combustion engine 12 and a first generator 14. The configuration of the engine system 10 can be variously changed according to the design requirements of the engine system 10.

  In the present embodiment, the internal combustion engine 12 is an open cycle reciprocating engine having at least four cylinders 31, 32, 33, 34. Each cylinder 31, 32, 33, 34 is provided with a piston 41, 42, 43, 44. Each piston 41, 42, 43, 44 is mechanically connected to an output shaft 49 via a rod 46, a shaft 48, and the like. The output shaft 49 is mechanically connected to the first generator 14 via a gear (not shown) or the like. The cylinders 31 and 32 are used for a suction / compression process, and the cylinders 33 and 34 are used for a combustion / expansion process. That is, the cylinders 31 and 32 (compression cylinders) and the cylinders 33 and 34 (combustion cylinders) are functionally separated according to the stage of the combustion cycle.

  The cylinders 31, 32, 33, and 34 are functionally connected to each other via a shaft 48, gears, and the like. In the internal combustion engine 12, for example, the number of compression cylinders is 2, and the number of combustion cylinders is 6. The number of cylinders is appropriately set based on the specifications of the internal combustion engine 12, the relative timing of the intake / compression process and the combustion / expansion process, and design factors such as the vibration mode. The phase angle difference of the operation cycle between the pistons 41, 42, 43, and 44 is set so that continuous motion is realized, and a flywheel is provided as necessary. For example, the number of suction / compression cylinders is 2, 3, 4, 5, 6, 7, 8, 9, 10, or 10 or more. For example, the number of combustion / expansion cylinders is 2, 3, 4, 5, 6, 7, 8, 9, 10, or 10 or more.

  The suction / compression cylinder 31 and the cylinder 32 are arranged in series. A first compression chamber 51 in which the piston 41 (compression piston) moves is formed in the cylinder 31, and a second compression chamber 52 in which the piston 42 (compression piston) moves is formed in the cylinder 32. The first and second compression chambers 51 and 52 have inlet ports 61 and 62 and outlet ports 63 and 64 in which control valves (not shown) are respectively arranged. In the internal combustion engine 12, each of the pistons 41 and 42 reciprocates once (2 strokes) during one operation cycle. The inlet port 61 of the first compression chamber 51 is fluidly connected to the fuel source 60 via the intake duct 57 and the fuel duct 58. Between the fuel source 60 and the inlet port 61, a fuel controller that controls the supply amount and / or the mixing ratio of the fuel may be arranged. Apart from the inlet port 61, the first compression chamber 51 may have a fuel port fluidly connected to the fuel source 60. In the present embodiment, gas fuel is supplied to the first compression chamber 51. Gaseous fuel may flow from the fuel source 60, and liquid fuel and gas (air) may be mixed before the first compression chamber 51. The outlet port 63 of the first compression chamber 51 is fluidly connected to the inlet port 62 of the second compression chamber 52 via ducts 71 and 72. A high compression ratio in the first and second compression chambers 51 and 52 is achieved by appropriately controlling valves (not shown) in the outlet ports 63 and 64, for example. When the internal combustion engine 12 has three or more compression cylinders, all the compression cylinders may be arranged in series, or the compression cylinders may be arranged in series and in parallel. Two or more cylinder groups arranged in series may be arranged in parallel with each other.

  The combustion / expansion cylinder 33 and the cylinder 34 are arranged in parallel. Expansion chambers 53 and 54 in which pistons 43 and 44 (expansion pistons) move are formed inside the cylinders 33 and 34, respectively. In the internal combustion engine 12, the pistons 42 and 44 reciprocate once (2 strokes) during one operation cycle. As an example, in each of the cylinders 33 and 34, for each reciprocation of the pistons 42 and 44, the ignition means (ignition plug 69) is operated as necessary to ignite the fuel. The expansion chambers 53 and 54 have inlet ports 65 and 66 and outlet ports 67 and 68, respectively, in which control valves (not shown) are arranged. The outlet port 64 of the second compression chamber 52 is fluidly connected to the inlet ports 65 and 66 of the expansion chambers 53 and 54 via ducts 73 and 74. The outlet ports 67 and 68 of the expansion chambers 53 and 54 are opened to the outside by being connected to an exhaust tower (not shown) via exhaust ducts 75 and 76, for example.

  In the present embodiment, the engine system 10 further includes a liquid supply device 16 that blows a cooling liquid onto the gas in the first compression chamber 51 and the gas in the second compression chamber 52, the regenerative heat exchanger 18, and the second. And a generator 20.

  The liquid supply device 16 includes spray nozzles 81 and 82 provided in the first and second compression chambers 51 and 52, a first separator 83 that removes liquid from the gas from the first compression chamber 51, and a second compression A second separator 84 for removing the liquid from the gas from the chamber 52; a first cooler 85 for cooling the liquid separated by the first separator 83; and a liquid separated by the second separator 84. And a second cooler 86. In this embodiment, the liquid supply device 16 circulates and uses a liquid for gas cooling, and a liquid replenisher is provided as necessary.

  The gas inlet of the first separator 83 is fluidly connected to the outlet port 63 of the first compression chamber 51 via the duct 71, and the gas outlet of the first separator 83 is second compressed via the duct 72. Fluidly connected to the inlet port 62 of the chamber 52. The gas inlet of the second separator 84 is fluidly connected to the outlet port 64 of the second compression chamber 52 via the duct 73, and the gas outlet of the second separator 84 is connected to the expansion chamber 53 via the duct 74. , 54 fluidly connected to the inlet ports 65, 66. Further, the first separator 83 and the spray nozzle 81 are fluidly connected via a duct 77, and a first cooler 85 that cools the liquid from the first separator 83 is disposed on the duct 77. . The second separator 84 and the spray nozzle 82 are fluidly connected via a duct 78, and a second cooler 86 that cools the liquid from the second separator 84 is disposed on the duct 78.

  The spray nozzle 81 is controlled to open and close by a control valve (not shown) and injects liquid into the first compression chamber 51 during gas compression. The form, number, position, and injection control method of the spray nozzle 81 are set so that the gas in the first compression chamber 51 is compressed almost isothermally by liquid injection. For example, as described in JP-T-2005-5021996 (International Publication WO2003 / 021107), at least two rows of fan-shaped spray nozzles can be arranged in the compression chamber in the circumferential direction, or JP-T-2001-502396. As described in the publication (International Publication No. WO 98/16741), a plurality of nozzles arranged in the circumferential direction and having the injection center direction inclined from the radial direction of the cylinder can be arranged in the compression chamber.

  In the present embodiment, the liquid ejection from the spray nozzle 81 is performed using the pressure increasing action of the first compression chamber 51. In accordance with the movement of the piston 41 in the first compression chamber 51, the pressure difference between the first compression chamber 51 and the internal space of the duct 77 is controlled by a control valve (not shown) or the like. The jetting liquid circulates in a path including the first compression chamber 51, the first separator 83, and the first cooler 85. The liquid flow in the circulation path is driven by a periodic pressure change in the first compression chamber 51. For example, as described in Japanese translations of PCT publication No. 2003-529720 (International Publication WO01 / 075308), a reservoir of liquid pressurized by compressed gas can be disposed on a liquid circulation path. The configuration of the injection system including the spray nozzle 82 of the second compression chamber 52 can be substantially the same as that of the spray nozzle 81 of the first compression chamber 51, and the liquid injection of the spray nozzle 82 is performed in the second compression chamber 52. This is done by using the pressurizing action. Within the allowable range, the above-mentioned special table 2005-501996 (International Publication WO2003 / 021107), special table 2001-502396 (International Publication WO98 / 16741), and special table 2003-529720 (International Publication WO01 / No. 075308) is incorporated herein by reference.

  The first and second separators 83 and 84 are provided outside the cylinders 31 and 32, respectively. The first separator 83 is a device that separates liquid and vapor from the gas-liquid two-phase flow that has exited the first compression chamber 51, so that the target performance is achieved and the pressure drop of the gas is reduced. The position and separation method are set. Also, the first separator 83 is preferably designed to function as a liquid reservoir and accumulator. The first separator 83 may have a plurality of separators, and has a multi-stage structure including a gas-liquid separator that roughly separates liquid and vapor and a moisture separator that further separates moisture in the vapor. There may be. As the gas-liquid separator, a gravity type, an inertial type, a centrifugal type, a coulomb type, etc. can be applied. For example, a centrifugal separator separates a two-phase flow by a swirling blade that rotates with the force of a two-phase flow, and causes liquid to adhere to the inner wall by centrifugal force. The configuration of the second separator 84 for the second compression chamber 52 can be substantially the same as that of the first separator 83 for the first compression chamber 51. A configuration in which the first and second separators 83 and 84 are provided inside the cylinder is also possible, but in this case, a dead volume corresponding to the size of the separators 83 and 84 is generated in the cylinders 31 and 32.

  The regenerative heat exchanger 18 is located between the second separator 84 and the cylinders 33 and 34, collects the heat of the exhaust gas from the expansion chambers 53 and 54, and gives the heat to the compressed gas from the second compression chamber 52. . In the regenerative heat exchanger 18, the compressed gas from the second compression chamber 52 and the exhaust gas from the expansion chambers 53 and 54 exchange heat, the compressed gas is heated, and the exhaust gas is cooled. In the present embodiment, the regenerative heat exchanger 18 can give the remaining heat given to the compressed gas to the steam generator 22. For example, a first heat exchanger for compressed gas is provided on the inlet side of the exhaust gas, and a second heat exchanger for steam production heat medium is provided on the downstream side of the first heat exchanger. The first heat exchanger and the second heat exchanger may be integrated or separate. As the configuration of the heat exchanger, various known techniques can be applied. In the present embodiment, the regenerative heat exchanger 18 is a countercurrent type in which a low-temperature fluid and a high-temperature fluid flow oppositely. A parallel flow type in which a high-temperature fluid and a low-temperature fluid flow in parallel can also be adopted. In the present embodiment, since the compression cylinders 31 and 32 and the combustion cylinders 33 and 34 are functionally separated and the compression cylinders 31 and 32 are arranged in a multistage series, the material flowing through the regenerative heat exchanger 18 will be described later. Maximum temperature is suppressed. This is advantageous for reducing the manufacturing cost of the heat exchanger.

  The second generator 20 is disposed between the combustion cylinders 33 and 34 (expansion chambers 53 and 54) and the regenerative heat exchanger 18, and the exhaust gas is discharged before the regenerative heat exchanger 18 along the flow of the exhaust gas. Recovers a part of the energy it has and converts it into effective power. The second generator 20 may have any configuration capable of recovering exhaust gas energy. For example, a turbine generator is applied. The turbine generator converts the rotational force obtained from the kinetic energy of the exhaust gas into electric power.

  Here, the cycle of the first and second compression chambers 51 and 52 and the expansion chambers 53 and 54 will be described.

  In the compression cylinder 31, the piston 41 reciprocates. Gas (gas fuel) is drawn into the first compression chamber 51 through the inlet port 61 as the piston 41 moves away from the top dead center of the stroke (the piston position at which the cylinder volume is minimized). The piston 41 that has reached the bottom dead center changes direction. The gas in the first compression chamber 51 is compressed as the piston 41 moves away from the bottom dead center of the stroke (the piston position where the cylinder volume becomes maximum) and approaches the top dead center.

  In the process of compressing the gas in the first compression chamber 51, the low temperature liquid from the first separator 83 is sprayed to the gas in the first compression chamber 51 through the spray nozzle 81. The supply of the low-temperature liquid suppresses the temperature rise of the gas in the first compression chamber 51, and the gas in the first compression chamber 51 is compressed almost isothermally. The spray nozzle 81 and control valves (not shown) at the inlet port 61 and the outlet port 63 are controlled to open and close according to the movement of the piston 41. Further, the liquid is sprayed into the first compression chamber 51 using the pressure difference between the first compression chamber 51 and the internal space of the duct 77. The pressure difference can be controlled by opening / closing control of the spray nozzle 81 according to the movement of the piston 41. Liquid supply using internal power is advantageous in reducing power and equipment costs compared to liquid supply using external power.

  In the first compression chamber 51, the weight ratio of liquid to gas (liquid / gas) is, for example, 0.1 to 100. This weight ratio is set according to the specifications of the internal combustion engine 12 such as the gas flow rate and the pressure ratio (compression ratio). The process in the first compression chamber 51 may be substantially isothermal compression (pseudo isothermal compression), and a certain amount of gas temperature change is allowed. By isothermal compression, the compression power is greatly reduced. For example, when the pressure ratio (gas pressure after compression / gas pressure before compression) is 20, the air flow rate is 2.7 kg / s, and the weight ratio of cooling water to gas (liquid / gas) is 1 to 10, Compared to isothermal compression, compression power of about 30 to 35% is reduced.

  The liquid contained in the compressed gas exiting from the first compression chamber 51 via the outlet port 63 is removed by the first separator 83. This liquid is cooled by the first cooler 85 and supplied to the spray nozzle 81 of the first compression chamber 51. As a result, liquid (liquid, mist, vapor) circulates through a path including the first compression chamber 51, the first separator 83, and the first cooler 85. If necessary, new liquid is replenished in this circulation path, but the replenishment amount is small. The heat absorbed by the circulating liquid in the compression step is released into the atmosphere by the first cooler 85 or is recovered in another medium.

  In the other compression cylinder 32, the piston 42 reciprocates. As the piston 42 moves away from the top dead center, the compressed gas from the first compression chamber 51 is sucked into the second compression chamber 52 through the inlet port 62. On the other hand, as the piston 42 whose direction has been changed at the bottom dead center approaches the top dead center, the gas in the second compression chamber 52 is further compressed.

  Also in the second compression chamber 52, substantially the same isothermal compression as the first compression chamber 51 is performed. That is, in the gas compression process in the second compression chamber 52, the low-temperature liquid from the second separator 84 is sprayed to the gas in the second compression chamber 52 through the spray nozzle 82. The supply of the low-temperature liquid suppresses the temperature rise of the gas in the second compression chamber 52, and the gas in the second compression chamber 52 is compressed almost isothermally. Control valves (not shown) at the spray nozzle 82 and the inlet port 62 and outlet port 64 are controlled to open and close in accordance with the movement of the piston 42. Further, the liquid is sprayed into the second compression chamber 52 by utilizing the difference between the pressure in the second compression chamber 52 and the pressure in the duct 78. The pressure difference can be controlled by opening / closing control of the spray nozzle 82 according to the movement of the piston 42.

  In the second compression chamber 52, the weight ratio of liquid to gas (liquid / gas) is, for example, 0.1 to 100, similarly to the first compression chamber 51. This weight ratio is set according to the specifications of the internal combustion engine 12 such as the gas flow rate and the pressure ratio (compression ratio). The process in the second compression chamber 52 may be almost isothermal compression (pseudo isothermal compression), and a certain gas temperature change is allowed. By isothermal compression, the compression power is greatly reduced. The pressure ratio of the second compression chamber 52 may be substantially the same as that of the first compression chamber 51 or may be different from that of the first compression chamber 51. The weight ratio (liquid / gas) of the second compression chamber 52 may be substantially the same as that of the first compression chamber 51 or may be different from that of the first compression chamber 51.

  The liquid contained in the compressed gas exiting from the second compression chamber 52 through the outlet port 64 is removed by the second separator 84. This liquid is cooled by the second cooler 86 and supplied to the spray nozzle 82 of the second compression chamber 52. As a result, liquid (liquid, mist, vapor) circulates through a path including the second compression chamber 52, the second separator 84, and the second cooler 86. If necessary, new liquid is replenished in this circulation path, but the replenishment amount is small. The heat absorbed by the circulating liquid in the compression step is released into the atmosphere by the second cooler 86 or is recovered in another medium.

  The compressed gas from the second compression chamber 52 that has passed through the second separator 84 enters the regenerative heat exchanger 18 where it is preheated (preheated) by the heat of the exhaust gas. The flow of the preheated compressed gas is branched according to the number of cylinders 33 and 34, for example. The branch position of the flow of the compressed gas is not limited to between the regenerative heat exchanger 18 and the cylinders 33 and 34, but may be between the second separator 84 and the regenerative heat exchanger 18.

In the combustion cylinders 33 and 34, the compressed gas from the second compression chamber 52 flows into the expansion chambers 53 and 54 through the inlet ports 65 and 66. When the gas in the expansion chambers 53 and 54 ignites, the combustion gas expands, and the pistons 43 and 44 are driven by the energy. In accordance with the movement of the pistons 43 and 44, the pistons 41 and 42 of the first and second compression chambers 51 and 52 are driven via the shaft 48, gears, and the like. By setting an appropriate phase angle difference between the pistons 41, 42, 43, and 44, continuous motion is realized.
In this way, the above cycle is repeated.

  Further, the output shaft 49 connected to the pistons 43 and 44 rotates, and the first generator 14 is driven. Control valves (not shown) at the inlet ports 65 and 66 and the outlet ports 67 and 68 are controlled to open and close according to the movement of the pistons 43 and 44. The pistons 43 and 44 that have reached the bottom dead center change direction. As the pistons 43 and 44 approach the top dead center, the combustion gas is discharged from the expansion chambers 53 and 54 via the outlet ports 67 and 68. Combustion gases from the expansion chambers 53 and 54 merge and then enter the second generator 20. Combustion gas merging reduces pressure fluctuations in the combustion gas. The second generator 20 is driven by the energy of the exhaust gas discharged from the expansion chambers 53 and 54. The second generator 20 recovers the waste energy or surplus energy of the system and converts it into effective power. When it passes through the second generator 20, the temperature and pressure of the exhaust gas decrease. The gas emitted from the second generator 20 is further recovered through the regenerative heat exchanger 18. After discharge processing such as reduction processing, exhaust gas is discharged to the outside.

  Thus, in the present embodiment, the suction / compression process and the combustion / expansion process are performed by different cylinders, and the compression cylinders 31 and 32 perform isothermal compression, thereby reducing the compression power. The Further, since the outlet temperature of the compressed gas is low along with the isothermal compression, high power generation efficiency is achieved by the regeneration cycle via the regeneration heat exchanger 18. In the regeneration cycle, the regeneration efficiency is higher as the gas temperature after compression is lower.

  Moreover, in this embodiment, since a multistage isothermal compression is performed, a high pressure ratio (for example, 20-200) is achieved only with a reciprocating compressor having high compression efficiency (87-92%). That is, it is not necessary to install a preload device such as a turbocharger (compression efficiency: 80 to 85%) in front of the cylinder. The reciprocating type can set a higher combustion temperature than the axial flow type, and has a smaller amount of combustion air and less compression power.

  Further, in the present embodiment, since a plurality of stages of isothermal compression is performed, a large amount of liquid spray into the compression chamber is possible. For example, a two-stage isothermal compression process can at least double the amount of spray compared to one stage with substantially the same conditions. That is, when the gas / liquid ratio (liquid / gas) in the one-stage isothermal compression process is 2 to 3, the gas / liquid ratio in the two-stage isothermal compression process can be 4 to 6. By adding a large amount of moisture to the gas, the mass flow rate is increased, and a cycle (HAT cycle) having high power generation efficiency and excellent operability is realized.

  Further, in the present embodiment, the outlet temperature of the compression cylinder 32 (the outlet temperature of the second compression chamber 52) is set lower than that of the one-stage isothermal compression by performing a plurality of stages of isothermal compression. . The outlet temperature of the compression cylinder 32 is set to be approximately the same or lower than, for example, any of 60 ° C., 55 ° C., 50 ° C., 45 ° C., 40 ° C., 35 ° C., and 30 ° C. When the compressed gas outlet temperature in the compression cylinder 32 is about 30 to 60 ° C., for example, heat recovery is possible until the exhaust gas outlet temperature (final temperature of the exhaust gas) in the regeneration heat exchanger 18 becomes about 110 to 140 ° C. or less. It is. Therefore, energy saving is high.

  In the present embodiment, since a part of the energy of the exhaust gas is recovered by the second generator 20 in the upstream of the regeneration heat exchanger 18 along the flow of the exhaust gas, the exhaust gas inlet in the regeneration heat exchanger 18 is recovered. The temperature is set low. Therefore, highly reliable regenerative heat exchange is performed at a relatively low temperature. In a configuration in which a compression cylinder and a combustion cylinder are arranged separately and a regenerative heat exchanger is arranged between them, the high temperature specification of the regenerative heat exchanger is avoided, so that durability, reliability, and economy are achieved. It is advantageous for improvement. For example, the use of high temperature heat resistant materials and high temperature designs are eased. The configuration in which the energy of the exhaust gas is recovered at the front stage of the regenerative heat exchanger greatly improves the temperature environment as compared with that at the rear stage.

  In the present embodiment, the gas temperature after compression is set lower than the minimum ignition temperature of the fuel, so that the fuel is not ignited in the compression process in the first and second compression chambers 51 and 52. That is, even if the premixed mixture of fuel and air is compressed, it does not ignite. Therefore, it is possible to supply fuel at normal pressure to the flow before compression, and a fuel compressor is not necessarily required.

  Further, in the present embodiment, the exhaust gas inlet temperature in the regenerative heat exchanger 18 is set low along with the energy recovery by the second generator 20, so that the compressed gas outlet temperature in the regenerative heat exchanger 18, that is, combustion The inlet temperature of the compressed gas in the cylinders 33 and 34 (expansion chambers 53 and 54) is set low. Therefore, the compressed gas outlet temperature in the regenerative heat exchanger 18 (the compressed gas inlet temperature in the combustion cylinders 33 and 34) can be set lower than the minimum ignition temperature of the fuel. The compressed gas inlet temperature in the combustion cylinders 33 and 34 is set to the same level or lower than, for example, any of 450 ° C., 400 ° C., 350 ° C., 300 ° C., and 250 ° C. By setting the temperature of the inflow gas to the fuel cylinders 33 and 34 to be low, the heat resistance of the valves and the circulation system in the combustion cylinders 33 and 34 is alleviated, which is advantageous for reducing the cost of the apparatus. The relaxation of the heat resistance avoids mechanical problems such as high temperature fusion (valve stick) of the valve and high temperature lubrication design when the combustion cylinders 33 and 34 are exposed to a high temperature and high pressure atmosphere.

  As described above, in the present embodiment, the engine system 10 is reduced along with the reduction of the compression power by the divided arrangement of the multistage compression cylinder and the combustion cylinder and / or the arrangement of the second generator 20 at the front stage of the regenerative heat exchanger. The overall temperature environment can be set at an economic level. Setting an appropriate temperature environment is advantageous for steam production using recovered heat, as will be described below.

In the present embodiment, the engine system 10 further includes a steam generator 22.
The steam generator 22 produces steam using the heat recovered from the exhaust gas and the heat recovered from the combustion / expansion cylinders 33 and 34, and a tank 110 for storing water as a heating medium; A jacket cooling circuit 112, an exhaust heat recovery circuit 114, and a steam compressor 116. In the present embodiment, the steam generator 22 generates low-pressure steam by vacuum boiling and obtains high-pressure steam by subsequent pressure increase.

  The tank 110 is provided with heat transfer tubes 121 and 122 (heating unit), a water supply port 124, and a steam discharge port 126. Supply port 124 is fluidly connected to water supply 130 via duct 128. The exhaust port 126 is fluidly connected to the vapor compressor 116 via a duct 132.

  The jacket cooling circuit 112 is located between the jacket 141 that covers the combustion and expansion cylinders 33 and 34, the heat exchanger 142 that releases the heat recovered from the cylinders 33 and 34, and the heat exchanger 142 and the tank 110. And a circulation pipe 143. In the present embodiment, water is used as a medium flowing through the jacket 141. As a cooling medium, it is also possible to use a mixture of water and other components (such as ethylene glycol), a liquid other than water, or a gas. The jacket cooling water absorbs the heat of the cylinders 33 and 34 (expansion chambers 53 and 54) through the jacket 141. The jacket cooling water pipe is provided with a valve and a pump (not shown) for transporting the cooling water as necessary. In the heat exchanger 142, the heat recovered from the cylinders 33 and 34 is transmitted to the intermediate medium flowing through the circulation pipe 143. The jacket cooling water cooled by the heat exchanger 142 enters the jacket 141 again. In this way, the jacket cooling water is repeatedly used for cooling the cylinders 33 and 34.

  In the present embodiment, the jacket cooling circuit 112 further includes a bypass circuit 145, a cooler 146 disposed on the bypass circuit 145, and a control valve 147. For example, the control valve 147 controls the bypass flow rate (the flow rate of the jacket cooling water flowing through the bypass circuit 145) based on the temperature measurement result of the jacket cooling water measured by a sensor (not shown). The heat of the liquid flowing through the bypass circuit 145 is recovered as, for example, hot water by the cooler 146. The jacket 141 is stably cooled by controlling the bypass flow rate according to the fluctuation of the steam demand. When the fluctuation of the steam demand is small, such a bypass circuit can be omitted.

  The intermediate medium flowing through the circulation pipe 143 transports heat received from the jacket cooling water to the tank 110. Examples of the intermediate medium include water, a mixture of water and other components (such as ethylene glycol), a liquid other than water, or a gas. The circulation pipe 143 is provided with a valve and a pump (not shown) for transporting the intermediate medium as necessary. The circulation pipe 143 includes a heat transfer pipe 121 provided in the tank 110.

  The exhaust heat recovery circuit 114 has a circulation pipe 150 between the regenerative heat exchanger 18 and the tank 110. Circulation pipe 150 includes a heat transfer pipe 122 provided in tank 110. In the regenerative heat exchanger 18, the intermediate medium flowing through the circulation pipe 150 absorbs the heat of the exhaust gas from the expansion chambers 53 and 54. The intermediate medium transports heat recovered from the exhaust gas to the tank 110. The circulation pipe 150 is provided with a valve and a pump (not shown) for transporting the intermediate medium as necessary.

  In the tank 110, water is supplied from a water supply source via the supply port 124. The amount of water supplied to the tank 110 is controlled so that the level of the water stored in the tank 110 falls within a predetermined range. For example, the supply amount of water is controlled based on the measurement result of a sensor (not shown) that measures the liquid level in the tank 110. The heat of the intermediate medium flowing through the heat transfer tube 121 and the heat of the intermediate medium flowing through the heat transfer tube 122 are transferred to the water in the tank 110. The internal space of the tank 110 is sucked by the vapor compressor 116 through the discharge port 126 and the duct 132 of the tank 110.

  Due to the suction action by the vapor compressor 116, the internal space of the tank 110 is decompressed. In the present embodiment, a control valve (not shown) (such as a flow control valve) on the ducts 132 and 133 and the steam compressor 116 so that the internal pressure of the tank 110 becomes a negative pressure (negative pressure) lower than the atmospheric pressure. Is controlled. For example, this control is performed based on the measurement result of a sensor (not shown) that measures the internal pressure of the tank 110. In the tank 110, the hot water heated by the heat transfer tubes 121 and 122 boils under reduced pressure. The hot water temperature of the tank 110 is, for example, 90 ° C to 130 ° C. Low-pressure steam generated in the tank 110 flows in the duct 132 toward the steam compressor 116.

  The vapor compressor 116 is disposed downstream of the tank 110. As the vapor compressor 116, various compressors such as an axial compressor, a centrifugal compressor, a reciprocating compressor, and a rotary compressor are applicable. The steam compressor 116 compresses the steam from the tank 110 and flows the high-pressure steam to the downstream duct 133. Such steam is supplied to a predetermined external facility such as a manufacturing plant, a cooking facility, an air conditioning facility, a power generation plant, and the like.

  As described above, in the steam generator 22, steam having a relatively low pressure and low temperature is generated by the heat recovered from the jacket 141 and / or the exhaust gas, and is compressed by the steam compressor 116 to have a relatively high pressure and high temperature. Get steam. Since the internal space of the tank 110 has a negative pressure, a reduction in primary energy (power saving) as a whole is expected as compared with direct steam production by a heat exchanger.

  That is, since the steam compressor 116 is used for heating in a relatively high temperature region, it is advantageous for shortening the temperature rising time and suppressing heat loss compared to heating by heat transfer. Further, the steam generator 22 can recover heat from various locations of the engine system 10 because the heat recovery temperature level is relatively low (for example, 90 ° C. to 130 ° C.). Depending on the heat recovery temperature level of the steam generator 22, the exhaust gas outlet temperature (final temperature of the exhaust gas) in the regenerative heat exchanger 18 can be set low, which is useful for power recovery and energy saving of the engine system 10. It is advantageous. For example, the final temperature of the exhaust gas is set to the same level or lower than any one of 130 ° C., 125 ° C., 120 ° C., 115 ° C., 110 ° C., and 100 ° C.

  In addition, the steam generator 22 is low in manufacturing cost and is less likely to cause serious problems. That is, most mechanisms do not need to be high pressure designs, such as the tank 110 need not be a high pressure vessel. Further, even if a malfunction occurs in the steam compressor 116, the water or steam in the tank 110 is not excessively pressurized. In addition, the heat recovered at a plurality of locations is suitable for use in steam production collectively, and therefore steam production using a plurality of heat sources can be realized with a relatively simple configuration.

  Thus, in the engine system 10 provided with this steam generator 22, the cogeneration which manufactures steam with electric power is implement | achieved. Moreover, this engine system 10 can be used as an electrothermal variable type that produces steam as necessary, as will be described below.

  In the present embodiment, as shown in FIG. 1, the steam generator 22 controls the bypass pipe 155 that guides the steam to the duct 77 through which the combustion gas from the expansion chambers 53 and 54 flows, and the amount of steam that flows through the bypass pipe 155. A control valve 157 can be provided. The control valve 157 controls the steam bypass amount (the flow rate of steam flowing through the bypass pipe 155) according to the demand amount of steam. That is, when the steam demand is small, the bypass flow rate increases, and when the steam demand is large, the bypass flow rate decreases. The steam flowing through the bypass pipe 155 is mixed into the combustion gas, and energy is recovered by the second generator 20 together with the combustion exhaust gas.

  Further, as shown in FIG. 1, the steam generator 22 has a nozzle 160 for supplying a liquid (water) to the compression chamber of the steam compressor 116 as necessary. The arrangement position of the nozzle 160 is, for example, at least one of an inlet and an outlet of the vapor compressor 116. If the steam compressor 116 is multi-stage, the nozzle 160 can be disposed between the stages of the steam compressor 116. A configuration in which the nozzle 160 and the liquid phase position of the tank 110 are connected via a pipe 162 is also possible. In this pipe configuration, the liquid in the tank 110 having a relatively high temperature is effectively used to supply the nozzle 160. Is done. For the ejection of the liquid from the nozzle 160, internal power such as a pressure difference between the inlet and outlet of the pipe may be used, or external power such as a pump may be used.

  In the process of compressing steam, the volume of steam is increased by directly mixing water or hot water into the cooling from superheated steam to saturated steam. Furthermore, by optimizing the supply amount and timing of water or hot water, the saturated steam at a relatively low pressure and low temperature can be directly changed to a saturated steam at a relatively high pressure and high temperature. As described above, the configuration provided with the mechanism for supplying the liquid to the compression chamber of the vapor compressor 116 has high flexibility with respect to the vapor specifications, such as being able to easily generate both saturated vapor and superheated vapor.

  In the present embodiment, the fuel is supplied to the flow before the compression process, but the present invention is not limited to this. For example, fuel may be directly supplied to the expansion chambers 53 and 54 using a fuel compressor, as in a general diesel engine. In this case, it is possible to use liquid fuel that cannot be premixed and compressed between fuel and air, or fuel having a low ignition temperature.

  In addition, in the combustion cylinders 33 and 34 (expansion chambers 53 and 54), in addition to the method of igniting the fuel by the ignition means (ignition plug 69), the fuel is injected by the compressed and preheated air. An ignition method can be employed.

  Moreover, in this embodiment, although the liquid is injected to the 1st compression chamber 51 via the spray nozzle 81 with the internal motive power using the periodic pressure change of the 1st compression chamber 51, it is not limited to this. For example, a system in which liquid is ejected from the spray nozzle 81 by a pump can be employed. In this case, the pump can be configured to obtain internal power from a rotating shaft connected to the piston. Alternatively, the pump may be driven using external power. The same applies to the second compression chamber 52.

  Further, in the liquid supply device 16, one separator 83, 84 and one cooler 85, 86 are disposed in each of the first and second compression chambers 51, 52, but the present invention is not limited to this. The number of compression chambers and the number of separators may be the same or different. The plurality of compression chambers share the separator and / or the cooler, thereby simplifying the apparatus and reducing the apparatus cost.

  There may also be a rotational speed difference between the compression cylinders 31 and 32 and the combustion cylinders 33 and 34. For example, in order to secure the heat transfer time between the gas and the liquid in the first and second compression chambers 51 and 52, the number of the compression cylinders 31 and 32 per unit time is smaller than the cycle of the combustion cylinder. can do. This is realized by arranging a gear device between the crankshafts of the first and second compression chambers 51 and 52 and the crankshafts of the expansion chambers 53 and 54.

  Further, in the present embodiment, the generator is driven by the internal combustion engine 12, but it can also be used for driving a rotary machine device such as a vehicle wheel or a ship propeller.

  The engine system 10 provided here is preferably applied to a power generation system, particularly a cogeneration system that produces steam together with electric power, but is not limited thereto. For example, the engine system 10 can be applied as a drive engine for a car or a ship.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

It is a whole lineblock diagram showing one embodiment of an engine system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine system (internal combustion engine system), 12 ... Internal combustion engine (heat engine), 14 ... 1st generator, 16 ... Liquid supply device, 18 ... Regenerative heat exchanger (heat exchanger), 20 ... 2nd generator 22 ... Steam generating device 31, 32 ... Compression cylinder, 33, 34 ... Combustion cylinder, 41, 42, 43, 44 ... Piston, 49 ... Output shaft, 51 ... First compression chamber, 52 ... Second compression chamber, 53, 54 ... expansion chamber, 57 ... intake duct, 58 ... fuel duct, 60 ... fuel source, 81, 82 ... spray nozzle, 83 ... first separator, 84 ... second separator, 85 ... first cooler, 86 ... second cooler, 110 ... tank, 112 ... jacket cooling circuit, 114 ... exhaust heat recovery circuit, 116 ... steam compressor, 121,122 ... heat transfer tube, 141 ... jacket, 142 ... heat exchanger, 143 ... circulation Piping, 145 ... Bypass circuit, 146 ... condenser, 147 ... control valve, 150 ... circulating pipe, 155 ... bypass line, 157 ... control valve, 160 ... nozzle, 162 ... pipe.

Claims (6)

A compression chamber in which the compression piston moves and the gas is compressed;
An expansion chamber in which an expansion piston moves and the gas from the compression chamber is combusted and expanded;
A fuel source of fuel combusted in the expansion chamber;
An output shaft operatively connected to the expansion piston;
A heat exchanger for exchanging heat between the gas from the compression chamber and the exhaust gas from the expansion chamber;
An internal combustion engine system comprising: a generator disposed between the expansion chamber and the heat exchanger and driven by exhaust gas from the expansion chamber.   The internal combustion engine system according to claim 1, wherein the temperature of the gas from the compression chamber heated by the heat exchanger is lower than a minimum ignition temperature of the fuel.   The internal combustion engine system according to claim 1, wherein the fuel source is fluidly connected to the compression chamber.   The internal combustion engine system according to any one of claims 1 to 3, further comprising a steam generation device that generates steam using heat generated by compression of the gas and / or combustion of the gas.   The internal combustion engine system according to claim 4, wherein the steam generator is capable of mixing at least a part of the steam into the exhaust gas from the expansion chamber. The internal combustion engine system according to any one of claims 1 to 5, further comprising a liquid supply device that blows a liquid that suppresses a temperature rise of the gas to the gas in the compression chamber.

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