In most of the vacuum crystalliser, vacuum is generally produced by means of a

ANS:C - steam jet ejector with a barometric condenser

In most vacuum crystallizers, vacuum is generally produced by means of a steam jet ejector with a barometric condenser. A steam jet ejector, also known as a steam ejector or ejector pump, is a device used to create a vacuum by entraining and compressing gases using steam as a motive fluid. The steam jet ejector operates based on the principle of the Venturi effect, where a high-velocity steam jet entrains gases from the system, creating a low-pressure zone that induces the flow of gases through the ejector. The barometric condenser is a component often used in conjunction with the steam jet ejector to provide additional condensation and removal of non-condensable gases from the system. It helps maintain the vacuum level and prevents the buildup of non-condensable gases, ensuring efficient operation of the vacuum crystallizer. Therefore, the correct option is steam jet ejector with a barometric condenser.