Patent Application
20200208542
The present invention relates to a system and method for eliminating the presence of droplets in a heat exchanger, i.e. the present invention relates to a system and method comprising a droplets sensor.
Turbines are essential elements used in power plants such as power plants run by thermodynamic power cycles such as the Rankine cycle, Kalina cycle, Carbon Carrier cycle and/or Carnot cycle. In power plants, a liquid is heated until it is converted in to dry gas which then enters a turbine to do work. The liquid is typically heated in a heat exchanger and the produced dry gas exits from the outlet port of the medium to be heated.
A problem which often arises in power plants is that the gas in not wholly dry, i.e. there are liquid droplets in the gas. The momentum of fast moving liquid droplets exiting from a heat exchanger damages turbine blades and shortens the life of the turbine. Turbines are typically the most expensive parts of power plants; hence, there is a need of eliminating the cost of repairing or replacing turbines with damaged turbine blades. A similar problem occurs with compressors which are coupled to heat exchangers, i.e. water droplets damage the compressor. Consequently, there is also a need of eliminating the cost of repairing or replacing compressors.
EP2674697 relates to a plate heat exchanger comprising a sensor arrangement for detecting the presence of liquid content in the evaporated fluid. The sensor arrangement comprises temperature (Tm) and pressure (Pm) sensors and is therefore dependent on the measurement of pressure. Furthermore, the sensor arrangement is placed in a system in which the heat exchanger is used as an evaporator. Hence, the sensor arrangement appears not to be adapted for use in a heat exchanger which is used as a boiler. Moreover, the system in EP2674697 comprises a compressor, i.e. the evaporated liquid is led to a compressor. Hence, it appears as if the sensor arrangement is not adapted to be used in a system comprising a turbine for power generation. Additionally, in the system described in EP2674697, the temperature of the second medium (i.e. the medium which transfers heat to the first medium which is to be evaporated) is not measured which results in less accurate and/or precise detection of droplets in the outlet port of the first medium.
Moreover, in some prior art systems, there is a device for separating droplets from the gas which is led to the turbine. Such a droplet separator is positioned between the outlet of the first medium (i.e. working medium) and the turbine. However, a droplet separator takes up space in the system, and moreover, is an additional cost which makes the system more expensive. Thus, there is a need for a system which is both space and cost effective.
Consequently, in view of the above, there is a need for a system and method for eliminating the presence of droplets in a heat exchanger which is not dependent on the measurement of pressure. Moreover, there is a need for a system and method for eliminating the presence of droplets in a heat exchanger which is adapted to be used in together with a turbine. Furthermore, there is a need for a system and method for eliminating the presence of droplets in a heat exchanger which is adapted to be used with said heat exchanger being a boiler. Additionally, there is a need for more accurate and/or precise detection of droplets in the outlet port of the first medium.
The first object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger.
A further object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger which is not dependent on the measurement of pressure.
A further object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger which is adapted to be used in together with a turbine.
A further object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger which is configured as a boiler.
A further object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger which is configured as an evaporator.
A further object of the invention is to provide a system and method for eliminating the presence of droplets in a heat exchanger which is accurate and/or precise in the detection of droplets.
A further object of the invention is to reduce cost of repair and replacement of turbines.
A further object of the invention is to reduce cost of repair and replacement of compressors.
A further object of the invention is to provide a cost-effective system and method for eliminating the presence of droplets in a heat exchanger.
The objects of the invention are attained by the first and second aspects of the invention. More importantly, the complex set of problems and disadvantages associated with prior art techniques are solved by said first and second aspects of the invention.
In a first aspect of the invention, there is provided a system for eliminating the presence of droplets in a first medium arranged to be heated by a second medium in a heat exchanger, wherein the heat exchanger has an (i) inlet port and an outlet port for the first medium, and (ii) an inlet port and an outlet port for the second medium, wherein the second medium transfers heat to the first medium,
said system comprising
In one embodiment, the first temperature sensor array comprises two temperature sensors being a first temperature sensor A and a first temperature sensor B, and wherein the controller is configured to control the device for regulating flow of the first medium to reduce the flow of the first medium into the heat exchanger if the measured temperature difference between the second temperature sensor array and either one of first temperature sensor A and a first temperature sensor B is higher than the setpoint temperature, wherein the controller is configured to control the device for regulating flow of the first medium to reduce the flow of the first medium into the heat exchanger until the measured temperature difference between the second temperature sensor array and either one of the first temperature sensor A and the first temperature sensor B is lower than or equal to the setpoint temperature.
In one embodiment, the second temperature sensor array comprises two temperature sensors being second temperature sensor C and a second temperature sensor D.
In one embodiment, said first medium is arranged to be boiled or evaporated and overheated to a selected overheating temperature by said second medium in said heat exchanger. In one embodiment said heat exchanger is therefore configured as a boiler or as an evaporator, for example selected from the group consisting of plate heat exchanger, plate-and-shell heat exchanger, plate-fin heat exchanger and shell-and-tube heat exchanger.
In one embodiment, the first temperature sensor array is arranged in a heat exchanger outlet port (3) of the first medium at a position (i) before the heat exchanger outlet port of the first medium, (ii) at the heat exchanger outlet port of the first medium, and/or (iii) after the heat exchanger outlet port of the first medium preferably in a tube (i.e. pipe) leading the first medium away from the heat exchanger.
In one embodiment, the first temperature sensor A and a first temperature sensor B are positioned: (i) at an approximately equal distance from the heat exchanger outlet port of the first medium, or (ii) an unequal distance from the heat exchanger outlet port of the first medium.
In one embodiment, the first temperature sensor A and a first temperature sensor B are positioned at a circumferential position 0-360° (i) before the heat exchanger outlet port of the first medium, (ii) at the heat exchanger outlet port of the first medium, and/or (iii) after the heat exchanger outlet port of the first medium, preferably the first temperature sensor A and a first temperature sensor B are positioned (i) at a top position, and/or (ii) at the bottom position, and/or (iii) at an angle of +/−45° within said circumferential position and/or (iv) anywhere within said outlet port.
In one embodiment, the setpoint temperature depends on the process conditions in the system, preferably said process conditions are at least one of the following: type of medium used as first medium, type of medium used as second medium, pressure(s) and flows in the system, ambient temperature, selected overheating temperature, differential temperature of the second medium between inlet port and outlet port of the heat exchanger.
In one embodiment, the setpoint temperature is preferably 10° C., more preferably 5° C., even more preferably 3° C., most preferably 2° C.
In one embodiment, the controller is a Proportional Integral Derivative (PID) controller or a PID controller in a Programmable Logic Controller (PLC).
In one embodiment, the at least one of the temperature sensors of the first and second temperature sensor arrays is a resistance temperature detector.
In one embodiment, at least one of the temperature sensors of the first and second temperature sensor arrays is a platinum resistance thermometer.
In one embodiment, at least one of the temperature sensors of the first and second temperature sensor arrays is a platinum resistance thermometer having a nominal resistance of 10-1000 ohms at 0° C., preferably a platinum resistance thermometer having a nominal resistance of 100 ohms at 0° C.
In one embodiment, the at least one of the temperature sensors of the first and second temperature sensor arrays is at least one temperature measuring wire.
In one embodiment, the at least one of the temperature sensors of the first and second temperature sensor arrays comprises two temperature measuring wires which may or may not intersect with each other.
In one embodiment, the at least one of the temperature sensors of the first and second temperature sensor arrays comprises two temperature measuring wires which are either configured in parallel, perpendicular or at any angle with respect to each other.
In one embodiment, the at least one of the temperature sensors of the first and second temperature sensor arrays comprises four temperature measuring wires wherein two of the wires are configured in parallel with respect to each other while the other two wires are configured in parallel with each other as well as configured perpendicular with respect to the other two wires.
In a second aspect of the invention, there is provided a method for eliminating the presence of droplets in a first medium arranged to be heated by a second medium in a heat exchanger, said method comprises the steps:
The method is characterized by the steps:
In one embodiment, the first temperature sensor array comprises two temperature sensors being a first temperature sensor A and a first temperature sensor B, and wherein the controller is configured to control the device for regulating the flow and to reduce of the first medium into the heat exchanger if the measured temperature difference between the second temperature sensor array and either one of first temperature sensor A and a first temperature sensor B is higher than the setpoint temperature, wherein the controller is configured to control the device for regulating the flow to reduce the flow of the first medium into the heat exchanger until the measured temperature difference between the second temperature sensor array and either one of the first temperature sensor A and the first temperature sensor B is lower than or equal to the setpoint temperature.
In one embodiment, the method comprises the step of measuring the second temperature by second temperature sensor array comprising two temperature sensors being second temperature sensor C and a second temperature sensor D.
In one embodiment the step of guiding first and second medium through a heat exchanger to transfer heat from a second medium to the first medium in said heat exchanger is configured to boil or evaporate the first medium and to overheat the first medium to a temperature above a theoretical boiling temperature by a heat transfer from said second medium.
In one embodiment, the method comprises the step of arranging the first temperature sensor array at a position (i) before the heat exchanger outlet port of the first medium, (ii) at the heat exchanger outlet port of the first medium, and/or (iii) after the heat exchanger outlet port of the first medium preferably in a tube leading the first medium away from the heat exchanger.
In one embodiment, comprises the step of arranging the first temperature sensor A and a first temperature sensor B at a position: (i) at an approximately equal distance from the outlet port of the first medium, or (ii) an unequal distance from the outlet port of the first medium.
In one embodiment, the method comprising the step of arranging the first temperature sensor A and a first temperature sensor B at a circumferential position 0-360° (i) before the outlet port of the first medium, (ii) at the outlet port of the first medium, and/or (iii) after the outlet port of the first medium, preferably the first temperature sensor A and a first temperature sensor B are positioned (i) at a top position, and/or (ii) at the bottom position and/or (iii) at an angle of +/−45° within said circumferential position and/or (iv) at any angle within said circumferential position.
In one embodiment, the second temperature sensor array is arranged at a position (i) before the inlet port of the second medium, (ii) at the inlet port of the second medium, and/or (iii) after the inlet port of the second medium.
In one embodiment, the second temperature sensor array, or sensors thereof, is/are positioned: (i) at an approximately equal distance from the inlet port of the second medium, and/or (ii) an unequal distance from the inlet port of the second medium.
In one embodiment, the second temperature array is positioned at a circumferential position 0-360° (i) before the inlet port of the second medium, (ii) at the inlet port of the second medium, and/or (iii) after the inlet port of the second medium, preferably the second temperature is positioned (i) at a top position, and/or (ii) at the bottom position.)
In one embodiment, the method comprises the step of setting the value of the setpoint temperature, wherein the value of the setpoint temperature is set depending on the process conditions in the system, preferably said process conditions process conditions are at least one of the following: type of medium used as first medium, type of medium used as second medium, pressure(s) and flows in the system, ambient temperature, selected overheating temperature ΔToverheat, differential temperature of the second medium between inlet port 6 and outlet port 7 of the heat exchanger.
In one embodiment, the setpoint temperature is preferably 10° C., more preferably 5° C., even more preferably 3° C., most preferably 2° C.
In one embodiment, the controller is arranged to receive data related to the resistance in said sensor, i.e. the first and second temperature sensor arrays is a resistance temperature detector or a temperature measuring wire, for example a platinum resistance thermometer.
In one embodiment, at least one of the temperature sensors of the first and second temperature sensor arrays is a platinum resistance thermometer having a nominal resistance of 50-1000 ohms at 0° C., preferably a platinum resistance thermometer having a nominal resistance of 100 ohms at 0° C.
Another aspect of the invention is the use of the system or method according to the above in a power plant, preferably said power plant employs a thermodynamic cycle selected from the group consisting of Rankine cycle, Kalina cycle, Carbon Carrier cycle and Carnot cycle, more preferably said power plant is a heat power generator, wherein said power plant comprises a circulating first medium, a heat exchanger in which said first medium is arranged to be heated by a second medium and wherein said heat exchanger is configured to boil or evaporate said first medium generating a gas, a turbine coupled to a power-generating device configured to generate electric power while expanding the gas, a condenser arrangement configured to condense the gas which has passed through the power-generating device, and a device for regulating flow of the condensed first medium into the heat exchanger.
The present invention relates to a system and a method for eliminating the presence of droplets in a first medium of a heat exchanger, i.e. the present invention relates to a droplets sensor. The heat exchanger may be configured as a boiler or an evaporator and is preferably selected from a plate heat exchanger, plate-and-shell heat exchanger, plate-fin heat exchanger, shell-and-tube heat exchangers, or variants thereof.
As illustrated in
The first medium and the second medium are selected from types of mediums or solutions comprising water, alcohols (such as methanol, ethanol, isopropanol and/or butanol), ketones (such as acetone and/or methyl ethyl ketone), amines, paraffins (such as pentane and hexane) and/or ammonia. However, the first medium and the second medium are preferably not the same solvent. Moreover, the boiling point of the first medium is preferably lower than the boiling point of the second medium.
The system and method further comprises at least one device 40, 41 which is configured for regulating the flow of the first medium into the heat exchanger 1 through the first medium inlet port 2. The device may be a valve 41, pump 40 and/or an injector or a combination of devices. Thus, when the controller 50 gives a signal to the device 40, 41 for regulating the flow the device is either; (i) reducing or opening the first medium inlet port area 2, (ii) reducing or increasing the rotation speed of the pump or injector, or (iii) both (i) and (ii).
The system and method further comprises a first temperature sensor array 10 and a second temperature sensor array 15. The first temperature sensor 10 array measures the temperature of the first medium exiting the heat exchanger 1 through first medium outlet port 3, while the second temperature sensor measures the temperature of the second medium entering the heat exchanger 1 through the second medium inlet port 6. The first and second temperature sensor arrays 10, 15 may each comprise one or more temperature sensors 10A, 10B; 15A, 15B, see
However, usage of other type of temperature sensors is also applicable. Hence, in alternative examples of the present invention, the temperature sensors of the first and second temperature sensor arrays may be one or more temperature measuring wires as illustrated in
The system and method further comprises a controller 50, e.g. PID controller, connected to the device 40, 41 for regulating flow of the first medium into the heat exchanger 1, the first temperature sensor array 10 as well as the second temperature sensor array 15. The controller 50 controls the device 40, 41 for regulating flow of the first medium into the heat exchanger based on data received from the first temperature sensor array 10 and second temperature sensor array 15.
The controller 50 gives a signal to the device 40, 41 for regulating the flow of first medium to reduce the flow of the first medium into the heat exchanger 1 if the measured temperature difference ΔT between the temperature T2 measured by the second temperature sensor array 15 and the temperature T1 measured by the first temperature sensor array 10 is higher than a setpoint temperature Tset.
ΔT=T2−T1ΔT>Tset
The temperature difference being higher than the setpoint temperature Tset indicates the presence of droplets in the first medium.
The controller 50 gives a signal to the device 40, 41 to reduce the flow of the first medium into the heat exchanger 1 through the first medium inlet port 2 until the measured temperature difference between the temperature T2 measured by the second temperature sensor array 15 and the temperature T1 measured by the first temperature sensor array 10 is lower than or equal to the set point temperature Tset. The setpoint temperature Tset depends on the type of medium or solvents used as first medium and second medium and the differential temperature of the second medium between inlet port 6 and outlet port 7. The setpoint temperature Tset may be 10° C., preferably 5° C., more preferably 3° C., most preferably 2° C.
The present invention works with overheated gas where the gas temperature is controlled to be a predefined number of degrees Celsius, ΔToverheat, higher than the theoretical boiling point for the first medium (i.e. working medium) at the actual pressure P of the gas outlet (i.e. outlet port 3 of the first medium) of the heat exchanger. Preferably, the well-known Antoine equation is used for determination of the theoretical boiling point. The number of degrees Celsius defined as overheating temperature, ΔToverheat, is set depending in what type of larger system or process, the system for eliminating droplets is adapted to be used.
An overheating of the first medium is possible by transferring heat from the second medium to the first medium by guiding the second medium and the first medium through the heat exchanger 1. Preferably all heat enthalpy of the second medium is transferred to the first medium, i.e. the temperature T1 of the evaporated gaseous first medium is near the temperature T2 of the incoming heat transferring second medium. Thus, there is a need to optimize the process and controlling the flow of first medium through the heat exchanger 1 based on the temperature difference between the temperature T2 of the incoming heat transferring second medium and the temperature T1 of the overheated and evaporated gaseous first medium at ideal evaporation comprising no droplets, this difference is the above-mentioned set point temperature Tset. The value of the setpoint temperature Tset is set depending on the process conditions in said system. Preferably said process conditions are at least one of the following: type of medium used as first medium, type of medium used as second medium, pressure(s) and flows in the system, ambient temperature, selected overheating temperature ΔToverheat, differential temperature of the second medium between inlet port 6 and outlet port 7 of the heat exchanger.
When the gas is overheated, liquid and droplets in the first medium of the heat exchanger has a lower temperature than the gas in the first medium. Thus, when a droplet touches the first temperature sensor array 10, the droplet will cool down the first temperature sensor array 10 immediately. Thus, if the measured temperature difference between the temperature T2 measured by the second temperature sensor array and the temperature T1 measured by the first temperature sensor array is higher than the setpoint temperature Tset, there are droplets in the working medium and the controller 50 is set to regulate the first medium flow (i.e. working media flow) into the heat exchanger by controlling the device 40, 41 for regulating the flow of the first medium.
Hence, the system and method of the present invention can optimize the heat exchanger to boil as much of the first medium as possible without getting droplets out of the heat exchanger port (i.e. outlet port of the first medium) with a controller such as a simple PID regulator or PID regulator in a PLC or other control system. This is the cheapest way to optimize the usage of a heat exchanger (such as a plate heat exchanger) as boiler without a separator connected to the heat exchanger.
In
In
The system and method according to the present invention may be used in any heat exchanger. In preferred embodiments of the invention, the system and method are used with heat exchangers used in power plants. In further preferred embodiments, the system and method are used with heat exchanger used in power plants employing thermodynamic cycles such as the Rankine cycle, Kalina cycle, Carbon Carrier cycle and/or Carnot cycle are used. Example of power plants in which the present invention may be used (but not limited to) are described WO2012128715, WO2014042580, WO2015034418, WO2015112075, WO2015152796, WO2016076779 and PCT/SE2016/050996. In further preferred embodiments, the system and method are used with heat exchanger which are coupled to a turbine and/or compressor. Examples of systems comprising a turbine are described in (but not limited to) WO2015112075. Examples of systems comprising a compressor are described in (but not limited to) WO2015034418.
An embodiment of the invention as described in
The plate heat exchanger 1 has an inlet port 2, 6 and an outlet port 3, 7 for both the first medium and the second medium. The first medium comprises acetone and is heated by the second medium which comprises water. The device 40, 41 which regulates the flow of the first medium, i.e. acetone, into the plate heat exchanger is a pump. However, in alternative embodiments, said device may be a combination of (i) pump and valve, or (ii) pump and injector. A further alternative is that said device may be a combination of pump, valve and an injector.
The system and method further comprises a first temperature sensor array 10 which measures the temperature of the acetone exiting the heat exchanger. The second temperature sensor array 15 measures the temperature of water entering the heat exchanger. The first temperature sensor array comprises a first temperature sensor 10A and a first temperature sensor 10B wherein each sensor is a resistance temperature detector such as a platinum resistance thermometer. A platinum resistance thermometer having a nominal resistance of 10-1000 ohms at 0° C. may be used as a temperature sensor. In preferred embodiments of Example 1, the temperature sensor is a platinum resistance thermometer having a nominal resistance of 100 ohms at 0° C. In some embodiments of Example 1, the first temperature sensor array may only comprise a single temperature sensor.
The system and method further comprises a PID controller which is connected to the pump, the second temperature sensor array, the first temperature sensor A as well as the first temperature sensor B. The PID controller controls the pump (or alternatively pump, valve and/or injector if such devices are present in the heat exchanger) for regulating flow of acetone into the heat exchanger based on data received from the second temperature sensor array, the first temperature sensor A and the first temperature sensor B. In embodiments of Example 1 in which the systems and method comprise pump, valve and/or injector as said device, the PID controller is connected to each of pump, valve and/or injector. More importantly, the PID controller controls each of pump, valve and/or injector. In some embodiments of Example 1, the PID-controller is part of a PLC.
The first temperature sensor array 10 is arranged at a position at the outlet port 3 of the first medium (or alternatively before or after the outlet port). The first temperature sensor 10A and a first temperature sensor 10B may be positioned either (i) at an approximately equal distance from the outlet port of the first medium, or (ii) an unequal distance from the outlet port of the first medium. Moreover, the first temperature sensor A and a first temperature sensor B may be positioned at a circumferential position 0-360° at the outlet port of the first medium (or alternatively before or after said outlet port). In preferred embodiments, one of first temperature sensor 10A and a first temperature sensor 10B is positioned at a top position while the other is positioned at the bottom position. The second temperature sensor array 15 is arranged at the inlet port 6 of the second medium (or alternatively before or after said inlet port) and is positioned at a circumferential position 0-360° at the inlet port 6 of the second medium. Preferably the second temperature sensor array 15 is positioned (i) at a top position, and/or (ii) at the bottom position.
Some of the positions of the first temperature sensor array 10 in the outlet port 3 of the first medium are illustrated in
The PID controller 50 reduces the flow of the first medium into the plate heat exchanger if the measured temperature difference between the second temperature sensor array 15 and either one of first temperature sensor 10A and a first temperature sensor 10B is higher than a setpoint temperature of 2° C. The flow of acetone into the plate heat exchanger 1 is reduced until the measured temperature difference between the second temperature sensor array and either one of the first temperature sensor 10A and the first temperature sensor 10B is lower than or equal to a setpoint temperature of 2° C.
In further embodiments of Example 1, acetone and water are replaced as first medium and second medium, respectively, with other solvents such as water, alcohols (such as methanol, ethanol, butanol and/or isopropanol), ketones (such as acetone and/or methyl ethyl ketone), amines, paraffins (such as pentane and hexane) and/or ammonia. When the first medium and/or second medium are replaced with one or more solvents, a new setpoint temperature is may be determined. However, in most cases the set point temperature remains the same. The new setpoint temperature may be within the interval of 1-10° C.
In preferred embodiments, the system and method of Example 1 is used in a gasketed plate heat exchangers which consists of many corrugated stainless-steel sheets separated by polymer gaskets and clamped in a steel frame. Inlet portals and slots in the gaskets direct the hot and cold fluid to alternate spaces between plates. The corrugation induce turbulence for improved heat transfer, and each plate is supported by multiple contacts with adjoining plates, which have a different pattern or angle of corrugation. The space between plates is equal to the depth of the corrugations. With liquid solutions on both sides, i.e. liquid solutions as first and second medium, the overall coefficient for a plate-type exchanger is several times the normal value for a shell-and-tube exchanger. Moreover, a plate-type exchanger is easily cleaned and sanitized.
The embodiments of Example 2 differ from the embodiments of Example 1 in that the system and method is applied in a heat exchanger which is a plate-and-shell heat exchanger which combines plate heat exchanger with shell and tube heat exchanger technologies.
The embodiments of Example 3 differ from the embodiments of Example 1 in that the system and method is applied in a heat exchanger which is a plate-fin heat exchanger, i.e. a heat exchanger which comprises plates and finned chambers to transfer heat between the first medium and the second medium. A plate-fin heat exchanger is made of layers of corrugated sheets separated by flat metal plates to create a series of finned chambers. Separate hot and cold fluid (i.e. second and first media) streams flow through alternating layers of the heat exchanger and are enclosed at the edges by side bars. Heat is transferred from one stream through the fin interface to the separator plate and through the next set of fins into the adjacent fluid/medium. The fins also serve to increase the structural integrity of the heat exchanger and allow it to withstand high pressures while providing an extended surface area for heat transfer.
The embodiments of Example 4 differ from the embodiments of Example 1 in that the system and method is applied in a heat exchanger which is a shell-and-tube heat exchanger. A shell-and-tube heat exchanger comprises a shell (i.e. a large pressure vessel) with a bundle of tubes (i.e. pipes) inside it. One fluid (e.g. first medium) runs through the tubes, and another fluid (e.g. the second medium) flows over the tubes (through the shell) to transfer heat between the two fluids (i.e. between the first medium and the second medium). The set of tubes is called a tube bundle, and may be composed of several types of tubes: plain, longitudinally finned. The preferred shell-and-tube heat exchanger may be selected from single-pas 1-1-exchanger, multipass exchanger (such as a 1-2 exchanger), 1-2 exchanger, 2-4 exchanger, cross-flow exchanger, or variants thereof.
The embodiments of Example 5 relate to the systems and methods described in Examples 1-4 which are applied in a waste heat power generator such as the one illustrated in
The waste heat power generator is a closed loop thermodynamic system, preferably an ORC system, comprises a circulating working medium, i.e. first medium, circulating through a turbine 20 coupled to a power-generating device 25 which is configured to generate electric power while expanding the gas which is produced in a first heat exchanger 1 by boiling and overheating the working medium by guiding a hot heat transferring second medium through the first heat exchanger. The gas which has passed through the turbine 20 and power-generating device 25 is condensed in a condensation arrangement 30 by cooling the gas with a cooling medium. The condenser arrangement 30 comprise a second heat exchanger 30a arranged to cool a stream of working medium and a separate condenser tank 30b to condense the working medium. The second heat exchanger 30a has an inlet 36 and an outlet 37 for the cooling medium as well as an inlet 33 and an outlet 32 for the working medium, i.e. an inlet 32 for the gas entering the condenser and an outlet 33 for the condensate.
A pump 40 conveys the working medium condensed at the condenser to the first heat exchanger 1. The working medium (i.e. the first medium) enters the first heat exchanger 1 via the inlet port 2 of the first medium and exits through the outlet port 3 of the first medium in the form of gas. The second medium enters the first heat exchanger via the inlet port 6 of the second medium and then exits via the outlet port 7 of the second medium.
The first temperature sensor array 10 is arranged at a position at the outlet port of the first medium 3 or alternatively before or after said outlet port. The second temperature sensor array 15 is arranged at the inlet port of the second medium 6 or alternatively before or after said inlet port. The first and second temperature sensor arrays may each comprise one or more temperature sensors.
The number of degrees Celsius which the working medium gas is overheated is defined as an overheating temperature, ΔToverheat, and this may be set, for example depending on turbine type and turbine characteristics.
The embodiments of Example 6 differ from the embodiments in Examples 1-5 in that there is no measurement of the temperature difference between the second temperature sensor array and the first temperature sensor array.
Instead, in the embodiments of Example 6, if the temperature sensor/sensors of the first temperature sensor array are indicating a lower temperature than expected, the controller regulates the first medium flow (i.e. working media flow) into the heat exchanger. Consequently, the embodiments of Example 6 optimize the heat exchanger to boil as much of the first medium as possible without getting droplets out of the heat exchanger port (i.e. outlet port of the first medium).
Furthermore, in further embodiments of Example 6, to optimize the boiling in the heat exchanger, the incoming liquid medium (i.e. second medium) to the heat exchanger may further be controlled by using the calculated boiling point for the working medium (i.e. first medium) at the gas outlet (i.e. outlet port of the first medium) pressure. This boiling point temperature is compared with heating liquid (i.e. second medium) temperature coming out of the heat exchanger. Using this differential value in a controller one can further optimize the boiling in the heat exchanger.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1750765-8 | Jun 2017 | SE | national |
This application is the U.S. National Stage of International Application No. PCT/SE2018/050612, filed 13 Jun. 2018, which claims priority to Swedish Patent Application No. SE 1750765-8, filed 16 Jun. 2017.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2018/050612 | 6/13/2018 | WO | 00 |
