Heat exchanger with integrated testing system

A heat exchanger apparatus comprising:

• a heating stage with a product side and a heating fluid side;
• a cooling stage with a product side and a coolant side, wherein said product sides of said heating and cooling stages are interconnected;
• at least one regeneration stage between said heating and cooling stages the product line extending from the heating stage, through the or each regeneration stage, and finally through the cooling stage to give up heat to incoming un-treated product and to be cooled to a final product desired temperature, wherein an inlet side of the product line enters the regeneration stage and then through the heating stage, providing in the regeneration stage:
• a raw product line which is pre-heated in a first side of the regeneration stage before final heating in the heating stage,
• a treated product line which enters the regeneration stage in an opposed, second side to give up heat to un-treated product;
• at least one product outlet valve;
• at least one pressure sensor;
• at least one pump, and
• a controller,
• wherein:
• the apparatus is configured to perform a back-pressure operation on each of the heating and cooling stages by venting the product sides and pressuring the heating and cooling fluid sides by control of said at least one product outlet valve and said at least one pump for a minimum duration, sufficient to cause removal of any debris from said stages;
• the controller is configured to perform, after said back-pressure operation, an integrity test by control of said at least one pump and said at least one product outlet valve by:
• causing a low pressure of fluid in the heating fluid side and the coolant sides, by controlling said at least one product outlet valve to vent each said side and then seal the side after flow of a liquid into said heating fluid and coolant sides;
• simultaneously pressurizing the interconnected product sides of said heating and cooling stages at a pressure dynamically maintained by control of the pumps in response to sensed pressure;
• and
• sensing pressure in one or both of the heating fluid side and the coolant side, and detecting a leak if said pressure rises excessively;
• said at least one pump is linked with the product line inlet via valves which are operable by the controller to isolate a product supply, and
• the controller is configured to perform an integrity test in:
• a first phase by pressurizing the product inlet and outlet sides, with the heating and cooling stage heating fluid and coolant sides at low pressure, so that the heating and cooling stages have high pressure on one side and low pressure on the other side, and in
• a second phase in which the or each regeneration stage is vented on one side by said at least on product outlet valve control and subsequently closed, so that one side of each regeneration stage is under high pressure and the other side is under low pressure, and
• wherein the controller is configured to monitor pressure with a said at least one pressure sensor and/or monitor flow with a flow meter in the low-pressure side and to generate a fail output if the pressure in the low-pressure side rises excessively and/or if a flow causing a pressure rise is detected by said flow meter.