Sincerely asking for help
Thread Content
As shown in the figure, pump normal pressure and normal temperature water into the closed loop (used for water cooling equipment, with a plate exchange for cooling in the middle) to make the pressure reach 2.0MPa, then start the circulation pump, with a head of 70 meters and a flow rate of 5m3/h. Question 1: A vertical centrifugal pump can be used for the first pump, but the manufacturer of the second pump says that the pump inlet pressure is too high and a centrifugal pump cannot be selected. How does high inlet pressure affect the pump? When the pump is started, under the action of centrifugal force, is the center pressure of the liquid vortex a vacuum or 2.0Mpa? Is it because the pressure difference between the inlet and the vortex center is too large, causing the deformation of the pump shaft and damage to the neck ring, or is it simply the mechanical seal that does not bear enough pressure and is damaged. I don't understand what effect excessive inlet pressure will have on the pump. Question 2: The first one uses a vertical centrifugal pump to pump water to 2.0 and then stops. The second one uses a vortex pump. The parameters are as shown in the figure. The vortex pump is used for circulation. The maximum pressure of the pump is 1.6MPa. Then whether the pipeline pressure level is >2.0+1.6 or >2.0+70 meters (the vortex pump is selected based on a head of 70 meters) ； If the vortex pump efficiency EFF is 20%, long-term operation will have any impact on the pump. Question 3: No matter which pump is selected, the circulating pump in the closed loop is always running. If the circulating pump pressure is selected to be greater than the pipe network resistance, will the pressure in the entire loop increase or have other changes? Question 4: Are there any suitable pumps for use in closed circuits? Please recommend.
Tips from the Design Institute: 1. The pump inlet pressure is too high. The main impact is that the A mechanical seal body cannot bear it and B the axial force cannot bear it. However, 2MPA is nothing to worry about. If you have an inlet of 5 cubic meters, 70 meters, and 2Mpa, choose an API pump (API requires that the pump can withstand pressure of 4MPa and above), and add a mechanical seal, there is basically no problem. However, the efficiency of this flow rate and head is generally very low. In addition, it is definitely not a vacuum. Think about it, how big is the lift of the pump if it reaches 2MPa from vacuum (200 meters is enough) 2. The pipeline of the closed system is calculated according to 2.0+0.7 plus the margin. Your pump is only used for circulation (like a heating system), so you must calculate the pipeline pressure drop so that the pump head = pipeline pressure drop. This will allow for stable operation. Otherwise, if the difference is too great, either the pipeline will lose pressure, or the system pressure will increase. The vortex pump is inherently inefficient, and there is basically no problem as long as it is in the priority working area. However, the life of this kind of pump is inherently worse than that of centrifugal pumps. 3. For closed circuit pumps, small centrifugal pumps and pitot tube pumps can be considered. Just meet the process requirements. This is a heating model with a water replenishing pump + circulating water pump.
If a positive displacement pump is used as a solution, there is no need to go through complicated calculations. We have a high inlet pressure circulation pump solution, a 7-piston reciprocating pump, which is particularly suitable for this situation where the flow rate is not large and there is no pulsation. In the attached sample booklet, there are two pages in the middle, which are the parameters of the high inlet pressure pump. If you need further technical exchanges, you can add me on WeChat. There are numbers on the website and sample books.
Small flow, high head, pipeline pressure 2.0MPa. Nowadays, the design pressure of ordinary hot water circulation pumps of this size is only 1.0MPa. To put it bluntly, you don’t want to spend money to buy API standard ones, and you also require the pump manufacturer to meet your conditions. Give it to me and I will tell you that you can’t choose it. The design pressure requirement of your pump, including the head, requires a theoretical design pressure of 3.0MPa, and a pump casing above ZE will do. During the pressure test, the manufacturer will do a non-penetration test of 4.0MPa. You say it's not troublesome, but the key is that the person you asked the question doesn't seem to want to be a factory willing to pay, and wants so many conditions for just a few dollars. Your budget won’t exceed 5,000 yuan, so I’ll give it to you.
The problem was too high-end. It turned out to be a water replenishing pump and a pipeline pressure pump. Pictures speak best. I just don’t know what the foreign picture below does. To my personal understanding, as long as the conditions are met, any pump you can choose is fine. It doesn't seem that complicated. It's just a random mix for laymen, for reference. :)
Haha, the circulation pump we bought costs more than 7W, and the water replenishing pump also costs more than 1W. I am mainly discussing this. I won't thank you for your reply.
Friends, I would like to ask, are vortex pumps and rotary casing pumps the same type of equipment?
Certainly not a class of device. Structural forms vary greatly. Just download it from Baidu