Apparatus including a steam generator and method of controlling the same

Abstract

Steam-generating apparatus ( 1 ) and method for controlling same, wherein said steam-generating apparatus ( 1 ) comprises a water reservoir ( 5 ), a boiler ( 6 ) for generating steam, a sensor ( 14 ) connected to the boiler ( 6 ) for detecting the temperature of or pressure in the boiler ( 6 ), a pump ( 7 ) configured to pump water from the reservoir ( 5 ) to the boiler ( 6 ), and a controller ( 15 ) configured to receive a signal from the sensor ( 14 ) and to control operation of the pump ( 7 ) in dependence on said signal, the controller ( 15 ) is configured to determine an amount of water within the boiler ( 6 ) and to control the pump ( 7 ) to supply water to the boiler ( 6 ) when the determined amount of water is less than a predetermined value; moreover, said controller ( 15 ) is arranged to determine the amount of water by measuring at least one time interval needed for predetermined increase in temperature or pressure of the boiler ( 6 ) and to compare the measured time interval with a predetermined value.

1 . A steam-generating apparatus comprising a water reservoir, a boiler for generating steam, a sensor connected to the boiler for detecting the temperature of or pressure in the boiler, a pump configured to pump water from the reservoir to the boiler, and a controller configured to receive a signal from the sensor and to control operation of the pump in dependence on the signal, wherein the controller is configured to determine an amount of water within the boiler and to control the pump to supply water to the boiler when the determined amount of water is less than a predetermined value, wherein the controller is arranged to determine the amount of water by measuring at least one time interval needed for a predetermined increase in temperature of or pressure in the boiler and to compare the measured time interval with a predetermined value. 
     
     
         2 . A steam-generating apparatus according to  claim 1  wherein the predetermined time value corresponds to a time interval for one or more known amounts of water to reach the predetermined increase in temperature or pressure. 
     
     
         3 . A steam-generating apparatus according to  claim 1  further comprising a control valve to allow steam to be released from the boiler, wherein the controller is configured to measure a time interval for an incremental increase in boiler temperature or pressure only when the control valve is closed and steam is prevented from being released from the boiler. 
     
     
         4 . A steam-generating apparatus according to  claim 3  wherein the controller is configured to start measurement of a time interval for an incremental increase in boiler temperature or pressure following closing of the control valve after steam has been released from the boiler, and after a predetermined time period has elapsed after closure of the control valve. 
     
     
         5 . A steam-generating apparatus according to  claim 1  wherein the controller is configured to operate the pump when the measured time interval for an incremental increase in temperature or pressure of the boiler is less than a predetermined time interval. 
     
     
         6 . A steam-generating apparatus according to  claim 1  wherein the controller is configured to operate the pump for a predetermined period of time in dependence upon the determined amount of water remaining in the boiler. 
     
     
         7 . A steam-generating apparatus according to  claim 1  wherein the predetermined value comprises a time interval for an incremental temperature or pressure increase of one or more known amounts of water within the boiler which are stored in one or more look-up tables within a memory unit of the controller. 
     
     
         8 . A steam-generating apparatus according to  claim 1  wherein the controller is arranged to further control the operation of the boiler in dependence upon a temperature or pressure signal from the sensor and stops the boiler heating water when the sensed temperature or pressure reaches a predetermined threshold value. 
     
     
         9 . A steam-generating apparatus according to  claim 1  wherein the sensor comprises a thermistor mounted to a metallic substrate and the metallic substrate is mounted to the boiler. 
     
     
         10 . A method of operating a steam generating apparatus which comprises a water reservoir, a boiler for generating steam, a sensor connected to the boiler for detecting the temperature of or pressure in the boiler, a pump configured to pump water from the reservoir to the boiler, and a controller configured to receive a signal from the sensor and control operation of the pump in dependence on the signal, the method comprising determining an amount of water within the boiler and controlling the pump to supply water to the boiler when the determined amount of water is less than a predetermined value, wherein the method comprises determining the amount of water by measuring at least one time interval needed for a predetermined increases in temperature of or pressure in the boiler, and comparing the measured time interval with a predetermined value. 
     
     
         11 . A method according to  claim 10  comprising measuring a time interval for an incremental increase in boiler temperature or pressure only when a control valve to allow steam to be released from the boiler is closed and steam is prevented from being released from the boiler. 
     
     
         12 . A method according to  claim 11  comprising starting measurement of a time interval for an incremental increase in boiler temperature or pressure following closing of the control valve after steam has been released from the boiler, and after a predetermined time period has elapsed after closure of the control valve. 
     
     
         13 . A method according to  claim 10  comprising operating the pump for a predetermined period of time in dependence upon the determined amount of water remaining in the boiler. 
     
     
         14 . A method according to  claim 10  wherein the step of comparing the measured time interval with a predetermined value comprises comparing a measured time interval with a predetermined time interval for incremental temperature or pressure increases of one or more known amounts of water within the boiler stored in one or more look-up tables within a memory unit of the controller. 
     
     
         15 . A method according to  claim 10  comprising controlling operation of the boiler in dependence upon a temperature or pressure signal from the sensor and stopping the boiler heating water when the sensed temperature or pressure reaches a predetermined threshold value.