What is a critical nozzle, at the catalytic triple swirl?

The critical nozzle is installed at the connection point between the four-spin flue gas outlet pipeline and the double-acting slide valve in the flue; its diameter is also calculated to ensure a certain pressure drop between the four-spin flue gas outlet and the flue, thereby guaranteeing the separation efficiency for the third and fourth spins

During the descent of the three-spin catalyst, a portion of the flue gas is needed to carry it; this portion must pass through the critical nozzle. This amount of flue gas typically accounts for 3-5% of the total flue gas volume – too much of it would be a waste and would not result in any further improvement in the efficiency of the three-spin mechanism； It is too small to affect the efficiency of the three-spin system; in school laboratories this is referred to as the pumping rate. You can think of it as \"pumping out\" the catalyst that has been separated by the three-spin system, in order to prevent backmixing

Here it is called a pressure-reducing orifice plate. The function of the critical nozzle is to control the amount of flue gas entrained during the feeding of the three-spin catalyst, thereby maintaining stable operation of the three-spin system. It has two functions: 1, serving as a flue gas passage to return the flue gas entrained by the three-spin catalyst back to the flue. Without this line, the four-spinner and the storage tank become dead zones, affecting the normal discharge of the three-spinner. 2. Control the amount of flue gas passing through, which is reflected by the concept of \"critical value\"; this ensures that when there are fluctuations in the pressure at the inlet of the three-spinner, the amount of flue gas flowing through the critical nozzles does not vary significantly, thereby maintaining stability in the amount of flue gas entrained by the catalyst in the three-spinner legs. As for how a critical nozzle achieves being “critical,” I have no idea! At first glance, the function of a pressure-reducing orifice plate is to reduce pressure. But why is it necessary to reduce pressure? Its pressure-reducing effect lies in lowering the linear velocity of the smoke gas flowing through the double-acting slide valve. As the linear velocity of the smoke gas decreases, the pressure difference across the double-acting slide valve is reduced, which in turn increases the sensitivity of the valve’s operation!

Reply to 4# 328104062: Pressure-reducing orifice plates and critical flow nozzles are not the same concept, and their functions are also different

Reply to 4# 328104062: A critical nozzle and a pressure-reducing orifice plate are two different things; they are not the same!

Refer to this article at http://www.doc88.com/p-69539143141.html to understand the function of the three-rotor critical nozzle; actually, it can be replaced； It is not the same as a pressure-reducing orifice plate; a pressure-reducing orifice plate is used to ensure that there is a certain pressure drop across the double-acting slide valve, thereby preventing the flow velocity in its passages from exceeding the speed of sound. It is usually installed behind the double-acting slide valve.

Control the amount of smoke emitted by the four rotors; it should not be too large nor too small

From the perspective of the flue gas flow: (1) The flue gas at the top of the regenerator enters the three-spinner, where most of the catalyst particles are separated. The flue gas exiting the three-spinner contains very little catalyst; this flue gas then goes to the catalytic flue gas turbine, which is used to recover the pressure energy and some of the thermal energy contained in the flue gas； From the flue gas outlet, the gas goes on to the CO furnace or the waste heat furnace. (2) The bottom ash hopper of the three-spinner unit contains the dust that has been separated; this dust carries some flue gas with it to the inlet of the four-spinner unit, where further catalyst separation takes place ； The dust (fine powder) at the bottom of the four-spinners collects in the metering tank; the material legs of the four-spinners that lead into this tank have their material level controlled by weight-driven valves. The airflow at the top of the four rotors enters the exhaust flue, and a \"critical nozzle\" must be installed before it enters the flue. The main function of the critical nozzle is to ensure normal feeding under the triple swirl mechanism by controlling a certain amount of air leakage in the entire separation system ； Critical nozzles are installed near the end of the flue gas main line at the outlet of the four-rotor airflow system; the amount of gas released through these nozzles is generally 3% to 5% of the total flue gas volume. It is said that in the new design, this amount of gas released will be less than 3% to 5%. Principle of critical nozzles: When smoke flows through a nozzle, a pressure drop is generated. The flow rate of smoke passing through the nozzle increases as this pressure drop increases. However, when the pressure drop reaches a certain level, namely the critical pressure drop, the flow rate of smoke through the nozzle no longer increases, regardless of how much the pressure behind the nozzle decreases. The flow velocity at this point is the critical flow velocity of the smoke, which is roughly equivalent to the speed of sound under those conditions. In this way, it serves to limit the flow rate of smoke