Our customers have many applications with chemical reactions that are conducted at high pressures. These applications frequently require precise gas dosing. You can replace organic solvents with more effective alternatives, like liquefied gases.
It is a gas at atmospheric pressure and room temperature turned into a liquid by cooling or compression. An example of this is liquefied carbon dioxide (CO2) which is an excellent extraction solvent for non-polar chemical compounds.
There are obstacles when using liquefied gas, such as difficulty in handling these liquid/gas substances and lack of dosing precision. Bronkhorst has taken note of these obstacles and worked on a solution.
The liquefied gases need to be dosed in the liquefied state for the application which operates at high pressure. To provide accurate dosing of these gases the process conditions must be precise so that the liquid gas will not be out gassed.
Our partners at Bronkhorst engineered a solution carefully considering the requirements of the application. The process solution for this dosing application consists of a WADose HP Lite pump with an attached heat exchanger, combined with a Bronkhorst Coriolis mass flow meter and an EL-PRESS pressure meter. The heat exchanger cools the pump to below freezing temperature to stimulate liquid forming and prevent outgassing. This provides steady pressure and prevents an unsteady liquid flow when dosing chemical compounds.
The combination of the WADose piston pump and the Coriolis allows accurate dosing of the liquefied gases. When stand-alone piston pumps are used, they are not sealed airtight and may exhibit wear over time. Their set point may deviate from the amount of chemical compound dosed. This is even more prevalent when dosing low flows in the range of ml/min. With this Bronkhorst solution, the dosed quantity is measured accurately in-situ using the Coriolis mass flow controller. This controls the pump by adjusting the flow. This self-monitoring system works continuously controlling the supply of liquefied gases ensuring necessary precision.
This process solution boosts liquefied gas, typically from a gas cylinder, into a liquid at a higher pressure of about 200 bars. The pressure is monitored by a digital electronic pressure meter – for measuring the process pressure as well as for safety functionality. This is to be sure that the pressure does not get higher than the devices or vessels in the process can withstand, to protect those components. No extra safety relief valves are necessary in this way.
In addition to the mass flow rate – which is fluid-independent – the mass flow controller also continuously measures the density of the chemical compound. This is an extra measure of monitoring whether or not the compound is fully in its liquid state – and to which can be responded immediately. Also the temperature of the dosed compound is monitored by the mass flow controller.
This pump/controller combination is a complete plug-and-play solution without any engineering hours needed to be spent. Control parameters are easy to modify using the intuitive interface.
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