Patent Application
20190001378
This application relates generally to warewashers such as those used in commercial applications such as cafeterias and restaurants and, more particularly, to a mobile clean-in-place unit for such warewashers.
Commercial kitchens often utilize multiple warewash machines that require regular cleaning, including occasional deliming in which the water flow paths along the rinse line, including the hot water booster, energy recovery unit, plate heat exchanger unit and/or the rinse piping needs, to be cleaned of scales or lime. Some machines include an integrated and automated delime system. However, some machines do not.
It would be desirable to provide a maintenance system to improve on the longevity and overall performance of warewash machines that do not include an integrated and automated delime system.
In one aspect, a mobile unit for cleaning warewashers at a facility includes a base structure with wheels to facilitate movement. A cleaning system is mounted on the base structure and includes a tank, an external recirculation delivery line running from the tank and including a pump therealong and an external recirculation return line running back to the tank. The delivery line and the return line are connectable to a warewash machine for recirculating liquid from the tank through the warewash machine and back to the tank for cleaning of the warewash machine.
The machine of the previous aspect may include an on-board controller that automatically carries out cleaning operations, or the machine may be a manual machine that is operator controlled.
In another aspect, a method of cleaning a warewasher in a facility involves: (a) utilizing a mobile unit having an on-board cleaning system that includes a tank, an external recirculation delivery line running from the tank, an external recirculation return line running back to the tank, and an internal recirculation line from the tank and back to the tank; (b) moving the mobile unit to a location of the warewasher; (c) connecting the external recirculation delivery line to a liquid input of the warewasher and connecting the external recirculation return line to a liquid output of the warewasher; (d) adding water and delimer to the tank; (e) operating the mobile unit to move the water and delimer along the internal recirculation line in order to mix the water and delimer into a cleaning solution; and (f) operating the mobile unit to move the cleaning solution along the delivery line, through the warewasher and back along the return line for cleaning of the warewasher.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Referring to
A controller 70 may be provided with connections to the sensors, valves and pumps to carry out cleaning operations for warewash machines. The controller 70 may be a separate processor and/or may be formed by integrated control logic or circuits of the sensors. In this regard, as used herein, the term controller is intended to broadly encompass any circuit (e.g., solid state, application specific integrated circuit (ASIC), an electronic circuit, a combinational logic circuit, a field programmable gate array (FPGA)), processor(s) (e.g., shared, dedicated, or group—including hardware or software that executes code), software, firmware and/or other components, or a combination of some or all of the above, that carries out the control functions of the unit 10 or the control functions of any component thereof.
By way of example, the unit 10 may be used for cleaning of a warewash machine as described below with a system preparation phase, followed by a cleaning phase followed by rinsing phase.
For system preparation, the unit 10 is first moved to the location of the warewash machine to be cleaned. The connectors 62 and 64 are connected to the required points on the warewash machine, connector 50 is connected to a fresh water input source, which may be a hot water source, and line 28 is connected to a suitable drain path. The unit is started (e.g., via an operator interface associated with the controller 70) and the controller 70 responsively opens the valve 52 to fill the tank 20 with fresh water while valves 54, 58 and 60 are closed. When the tank fills to the lower level indicated by the sensor 36, the controller turns on the delimer pump 46 to dose a predetermined amount of delimer from the delimer container 44. The controller then turns on the circulation pump 56 and opens valve 58 while valves 54 and 60 remain closed to mix the deliming solution while the tank continues to fill via the input line 22. The mixing operation may be continuous (pump 56 on continuously) or intermittent (pump 56 switching from on to off a number of times) until the tank fills to its highest level as indicated by sensor 34. While filling and mixing, sensor 40 measures and senses the deliming solution concentration in the tank and the controller 70 compares the detected concentration with a preset desired concentration (e.g. stored in memory). The delimer pump 46 is controlled to dose more chemical until the deliming solution in the tank is at or close to the desired concentration. A number of different preset concentrations may be provided in memory and selectable based upon, for example, designation of the type of warewash machine being cleaned.
Once the system is ready, with tank filled and proper solution concentration achieved, the cleaning process is carried out by closing, or maintaining closed, valves 52, 54 and 58 and opening valve 60 and turning on the circulation pump 56 to circulates the deliming solution from the tank 20 to the warewash machine and back. The controller 70 monitors the progress of the deliming process by evaluating the difference between the indication from the delime solution strength sensor 40 and a preset point, as explained more fully below.
For initial progress monitoring, the rate of solution change (RC) as defined by Equation (1) below, which is the difference between the concentration set point and the actual deliming solution concentration (e.g., TDS or conductivity) over a predetermined time t during the early external circulation process, is used to monitor the early progress of the deliming process.
An initial high RC value above a recommended value (e.g., above an acceptable predefined range) at the early stages of the deliming process suggests that more delimer is required because the delimer is being used up rapidly in the process. In this case the delimer pump 46 is turned ON and doses until the RC value is within the recommended rate at the early stage of the process.
The end point for the cleaning process is also determined as follows. After the early stages, the solution TDS/Conductivity will be sensed or measured by sensor 40 over a predetermined time where a current solution TDS/Conductivity, say S2, will be compared with a previous solution TDS/Conductivity, say S1, to define a new solution concentration rate of change (RCe) as in Equation (2).
While the deliming process progresses, the deliming pump 46 will intermittently dose small predetermined amounts of delimer while sensor 40 measures or senses the solution concentration or strength in a predetermined time after dosing of the delimer for “n” number of times. Very low RCe values (e.g., below a set low threshold) for “n” number of measurements suggest the deliming process is close to completion (because the delimer concentration is not changing significantly) and the circulation pump 56 is then turned OFF after a predetermined time period.
In the course of the deliming process, sensor 42 monitors the base of the tank 20 to selectively drain out solids that settle and build up in the tank. The ON/OFF state of the in-line heating element 66 is controlled according to temperature sensed by sensor 38, where a threshold minimum desired temperature for the solution is set and element 66 controlled to maintain the minimum threshold.
The drain valve 54 is opened to drain the tank at a predetermined time after the pump 56 is stopped at the end of the cleaning process. A rinsing step can then be carried out. In particular, the tank 20 is drained until an acceptable reading from sensor 42 is achieved, and then the valve 52 is again opened to deliver fresh water while valve 54 remains open to allow flushing off some debris from the bottom of tank 20. The drain valve 54 is then closed a set time after valve 52 opens and the tank 20 fills. Valve 52 is closed when the fluid in the tank gets to the high level indicated by sensor 34, at which time valve 60 is opened and pump 56 is turned ON to activate the fresh water circulation to the warewash machine for a predefined rinse time period. After the predetermined time of rinse circulation, valve 58 is opened and valve 60 is closed, to also rinse of the recirculation line 31 of deliming solution for a set time period. The drain valve 54 is then opened to drain the spent deliming solution until the level in the tank reaches the lower level indicated by sensor 36, at which point the circulation pump 56 is turned OFF shut down for draining to occur under gravity. The drain valve 54 is closed a predetermined time after sensor 42 reads a predetermined value. The unit 10 can then be disconnected from the warewash machine and stored or moved to another warewash machine to carry out another cleaning process.
Referring to
The use of mobile clean-in-place units or modules enable cleaning (primarily deliming) multiple warewash machines in a given establishment. The units may include a sensor or meter for detecting solids or change in density to initiate draining of the unit tank. The use of rate of change analysis in solution concentration in such units facilitates monitoring progress of the deliming operations.
It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible.
| Number | Date | Country | |
|---|---|---|---|
| 62525808 | Jun 2017 | US |
