AN IMPROVED METHOD OF REDUCING PRODUCT LOSS

摘要

The present invention relates to a method of reducing product loss. Particularly, although not exclusively, the present invention relates to a process control unit and method for reducing product loss during vessel changeovers as shown in Figure 2. A method of continuously supplying a steady flow of fluid to a process stream from two or more vessels in a processing unit wherein the process includes: (a) at least two vessels; (b) a holding vessel into which the two vessels drain via separate draining mechanisms; (c) at least one surge restrictor valve that is capable of controlling flow of a fluid from each vessel and prevents backflow from a second or other vessel; (d) isolation valves located between the surge restrictor valve(s) outlet and the draining mechanism outlet(s) to the holding vessel; (e) at least one discharge pump which transports fluid from the holding vessel to the process stream; and, characterised in that the method includes the steps of: i) the first vessel empties fluid to the holding tank through the surge restrictor valve; ii) when the first vessel fluid level reaches a predetermined level, a control system opens the isolation valve from the second vessel, or subsequent vessel; iii) backflow due to gravity from the second vessel to the first vessel via the draining mechanism of the first vessel is halted by the surge restrictor valve; and, iv) the control system closes the isolation valve from the first vessel.