Selection of working steam pressure
Generally, the higher the working steam pressure, the less working steam and cooling water will be consumed. However, when the working steam pressure is too high, the above rules are not obvious. This is because too high steam pressure will result in increased expansion and increased nozzle length, which will result in increased nozzle loss. And the higher the steam pressure, the higher the cost of steam production and equipment investment. So a normal working steam pressure is selected in the range of 0.4 to 1.6 MPa (gauge pressure). When the working pressure of the pump is low (for example, less than 133Pa), in order to use the waste heat of the exhaust gas, reduce the influence of the first and second surface layers of the multistage jet pump and improve the workability of the nozzle. The lower limit of the working steam pressure can be selected It is 0.25 MPa.
Selection of dryness and temperature of working steam
Generally, neither superheated steam nor saturated working steam will affect the performance of the pump. However, due to the heat dissipation of the steam pipe and the expansion of the working steam in the nozzle, the steam becomes humid, which makes the performance of the pump unstable. When the working steam pressure is low, the expansion of the pump nozzle is very large, so the steam is in a “super-cooling” state. If the working steam contains solid particles or liquid droplets, it may become the center of condensation, causing the steam to condense suddenly. This not only causes the static pressure of the working steam in the nozzle to increase and reduce the speed, but also causes water to accumulate in the nozzle. Nozzle wear and corrosion increase. Therefore, it is generally appropriate to select a working steam superheat degree of 10-20°C and a steam dryness degree greater than 96%. The working steam is too hot, which not only wastes energy but also makes the pump unstable.
Selection of cooling water
The lower the inlet temperature of cooling water of the condenser, the less cooling water will be consumed.This is because the condensing capacity of the condenser can be increased and the load of the next pump can be reduced.Ordinary cooling water can make the temperature difference between the inlet and outlet larger.When the suction pressure is high, the cooling water temperature has little effect on the steam and water consumption because of the higher temperature of the steam mixture passing through the condenser.