Heating system and method of heating a process medium
The present disclosure relates to a heating system comprising: a heating arrangement for heating a process medium; an inverter configured to receive an input direct-current voltage from a power supply and to produce an intermediate alternating-current voltage; a transformer configured to receive the intermediate alternating-current voltage produced by the inverter and to supply an output alternating-current voltage to the heating arrangement; a sensor arrangement configured to generate a first sensor output signal indicative of a thermodynamic parameter of the process medium or the heating arrangement; and a controller configured to control the inverter based on the first sensor output signal.
1 . A heating system comprising:
a heating arrangement for heating a process medium;
an inverter configured to receive an input direct-current voltage from a power supply and to output an intermediate alternating-current voltage;
a transformer coupled to the heating arrangement and configured to receive the intermediate alternating-current voltage outputted by the inverter and to supply an output alternating-current voltage to the heating arrangement;
a sensor arrangement configured to generate a first sensor output signal indicative of a thermodynamic parameter of the process medium or the heating arrangement; and
a controller configured to output a pulse width modulated control signal to control the intermediate alternating-current voltage of the inverter based on the first sensor output signal, wherein the controller is further configured to output the pulse width modulated control signal to control the inverter such that the intermediate alternating-current voltage has a constant frequency which matches a predetermined operating frequency of the transformer, the predetermined operating frequency of the transformer being greater than 60 Hz.
2 . The heating system of claim 1 , wherein the thermodynamic parameter comprises a temperature of the process medium or the heating arrangement.
3 . The heating system of claim 1 , wherein the thermodynamic parameter comprises a sheath temperature of the heating arrangement.
4 . The heating system of any claim 1 , wherein the process medium comprises a process fluid.
5 . The heating system of claim 4 , wherein the thermodynamic parameter comprises: a temperature of the process fluid, a density of the process fluid; a viscosity of the process fluid; or a pressure of the process fluid.
6 . The heating system of claim 1 , wherein the sensor arrangement is further configured to generate a second sensor output signal indicative of the input direct-current voltage from the power supply, and wherein the controller is further configured to control the inverter based on the second sensor output signal.
7 . The heating system of claim 1 , wherein the sensor arrangement comprises a thermocouple, and wherein the thermocouple is configured to generate the first sensor output signal.
8 . The heating system of claim 1 , wherein the sensor arrangement comprises an infrared sensor configured to generate the first sensor output signal.
9 . The heating system of claim 1 , wherein:
the first sensor output signal is indicative of a thermodynamic parameter of the process medium;
the sensor arrangement is further configured to generate a third sensor output signal indicative of a thermodynamic parameter of the heating arrangement; and
the controller is configured to control the inverter based on the first sensor output signal and the third sensor output signal.
10 . The heating system of claim 9 , wherein:
the process medium is a process fluid;
the sensor arrangement is further configured to generate a fourth sensor output signal which corresponds to a velocity or a flow-rate of the process fluid; and
the controller is further configured to control the inverter based on the fourth sensor output signal.
11 . The heating system of claim 1 , wherein the inverter is configured to receive an input direct-current voltage of at least 1000 V and the transformer is configured to supply an output alternating-current voltage to the heating arrangement having a root mean square voltage of at least 1000 V.
12 . The heating system of claim 1 , wherein the transformer is an isolation transformer or an auto-transformer.
13 . The heating system of claim 1 , wherein
the heating arrangement comprises a plurality of heating elements;
the inverter is a multiple-phase inverter configured to receive an input direct-current voltage from the power supply and to output a plurality of intermediate alternating-current voltages; and
the transformer is a multiple-phase transformer configured to receive the plurality of intermediate alternating-current voltages outputted by the inverter and to supply a respective output alternating-current voltage to each of the plurality of heating elements.
14 . An installation comprising a heating system in accordance with claim 1 , the power supply and a heating vessel for receiving a process medium, wherein the power supply provides, in use, a substantially variable input direct-current voltage to the inverter.
15 . The installation of claim 14 , wherein the power supply comprises at least one of:
a battery;
a capacitor;
a supercapacitor;
a solar cell;
an array of solar cells;
a DC supply from an electrical utility; or
a rectified and/or filtered AC supply from at least one of a generator, a wind turbine and a hydroelectric turbine.
16 . A method of operating the heating system of claim 1 , the method comprising:
receiving an input direct-current voltage from the power supply;
providing the first sensor output signal to the controller;
controlling the inverter based on the first sensor output signal; and
supplying an output alternating-current voltage to the heating arrangement.
17 . A non-transitory computer-readable storage medium comprising instructions which, when executed by a processor, cause the processor to carry out the method of claim 16 .
18 . A data processing system comprising a processor configured to perform the method of claim 16 .
19 . The heating system of claim 1 , wherein the predetermined operating frequency of the transformer is 400 Hz.
20 . A method of retrofitting a heating system comprising a heating arrangement for heating a process medium, the method comprising:
providing an inverter to the heating system, wherein the inverter is configured to receive an input direct-current voltage from a power supply and to output an intermediate alternating-current voltage;
coupling a transformer to the heating arrangement and to the inverter, wherein the transformer is configured to receive the intermediate alternating-current voltage from the inverter and to supply an output alternating-current voltage to the heating arrangement;
positioning a sensor arrangement within the heating system, wherein the sensor arrangement is configured to generate a first sensor output signal indicative of a thermodynamic parameter of the process medium or the heating arrangement; and
coupling a controller to the inverter and to the sensor arrangement, wherein the controller is configured to output a pulse width modulated control signal to control the intermediate alternating-current voltage of the inverter based on the first sensor output signal, and wherein the controller is further configured to output the pulse width modulated control signal to control the inverter such that the intermediate alternating-current voltage has a constant frequency which matches a predetermined operating frequency of the transformer, the predetermined operating frequency of the transformer being greater than 60 Hz.