渣浆泵的零部件设计

国际标准化组织(ISO)将离心泵分为三类: I类技术泵，要求最严，即石油及石油化工用系; II类技术泵，要求中等，即化工用泵;III类技术泵，要求最松，即一般清水泵。本章主要介绍要求较高的离心泵设计，其他两类简单阐述。设计人员可根据实际情况(包括表面粗糙度、尺寸配合精度、几何公差、间隙、技术要求等)灵活运用。对于高压锅炉给水泵、军工用泵、核电用泵等，即便是输送清水，也绝不能简单套用上述划分方式，它们都有各自的标准，设计人员需根据具体要求酌情处理。

6.1单级泵、两级泵零部件设计
6.1.1
叶轮设计
常用叶轮结构型式如图6-1可以是整体铸件锻件或焊接件。

1. 闭式叶轮设计      

闭式叶轮结构如图6-1a~c所示。

1) 材料及铸件热处理技术要求见表2-2。     

2) 静平衡处理。一般静平衡G6.3 级，有时要转化为克验收(见本书 7.6.1)，不平衡质量允差可以按表6-1 选取。

 3)前后盖板加工要用样板检验，其表面粗糙度应符合本书2.5.3的要求。

 4)一般叶轮前后盖板上都有密封环，很多还另镶有后盖板叶轮密封环。清水泵和化工泵一般不需要镶后盖板叶轮密封环。密封环固定方式及配合详见本书7.7.3。

5)叶轮与轴配合公差为H7/h6。

6) 有后密封环时(见图6-1a)，其平衡孔总面积应为后密封环间隙环形面积的3~4倍。

7)没有后密封环时(见图6-1b)，一般增加背叶片平衡轴向力。但API 610标准不推荐采用背叶片来平衡轴向力，因为此方法并不可靠.
8)当泵扬程不高时，可以没有后密封环(见图6-1c)，也没有背叶片，泵产生的较小轴向力可由滚动轴承承受。

9)前后盖板出口处，不倒大角(见图6-1f)， 便于动、静平衡去重。 

10) 叶轮固定:径向采用平键固定，轴向采用叶轮螺母固定

2.半开式和开式叶轮设计

半开式和开式叶轮设计如图6-1d、e所示。

叶轮只有一个盖板，一般是没有前盖板，有的是没有后盖板，很多技术要求是与闭式叶轮相同的，不同之处说明如下:

1)叶轮是开式时，裸露叶片与相对应的耐磨板均要用样板加工检验。

2)耐磨板和裸露叶片加工完后，两者应对研，涂色检查，均匀接触面积不少于50%。这项工作一一定要做，绝对不可以忽略此项工作。

Parts Design of Slurry Pump

The International organization for Standardization (ISO) divides centrifugal pumps into three categories: Class I technical pumps, which are the most stringent, namely, petroleum and petrochemical systems; Class II technical pump, with medium requirements, i.e. chemical pump; Class III technical pump, with the most loose requirements, is the general clean water pump. This chapter mainly introduces the design of centrifugal pumps with high requirements, and the other two categories are briefly described. Designers can flexibly use it according to actual conditions (including surface roughness, dimensional fit accuracy, geometric tolerance, clearance, technical requirements, etc.). For high-pressure boiler feed water pump, military pump, nuclear power pump, etc., even if it is used to transport clean water, the above classification method must not be simply applied. They all have their own standards, and the designers need to deal with them according to specific requirements.

6.1 Parts design of single-stage pump and two-stage pump

6.1.1

Impeller design

As shown in Figure 6-1, the common impeller structure type can be integral casting forgings or weldments.

1. Closed impeller design

The structure of closed impeller is shown in Fig. 6-1a~c.

1) See Table 2-2 for technical requirements for heat treatment of materials and castings.

2) Static balance treatment. Generally, static balance grade G6.3 is sometimes converted to gram acceptance (see 7.6.1 of this book), and the tolerance of unbalanced mass can be selected according to Table 6-1.

3) The processing of front and rear cover plates shall be inspected with a sample plate, and the surface roughness shall meet the requirements of 2.5.3 of this book.

4) Generally, there are sealing rings on the front and rear cover plates of the impeller, and many of them are also embedded with the rear cover plate impeller sealing ring. Clean water pump and chemical pump generally do not need to insert the back cover impeller seal ring. See 7.7.3 of this book for the fixing method and matching of sealing ring.

5) The fitting tolerance between impeller and shaft is H7/h6.

6) When there is a rear seal ring (see Fig. 6-1a), the total area of the balance hole shall be 3~4 times of the annular area of the rear seal ring gap.

7) When there is no rear sealing ring (see Fig. 6-1b), the balance axial force of the back blade is generally increased. However, API 610 does not recommend the use of back blades to balance the axial force, because this method is not reliable

8) When the pump lift is not high, there can be no rear seal ring (see Fig. 6-1c) or back blade, and the smaller axial force generated by the pump can be borne by the rolling bearing.

9) At the outlet of the front and rear cover plates, there is no chamfer (see Fig. 6-1f), which is convenient for dynamic and static balancing and weight removal.

10) Impeller fixation: flat key is used for radial fixation, and impeller nut is used for axial fixation

2. Semi open and open impeller design

The design of semi open impeller and open impeller is shown in Fig. 6-1d and e.

Impellers have only one cover plate. Generally, there is no front cover plate, and some have no rear cover plate. Many technical requirements are the same as those for closed impellers. The differences are described as follows:

1) When the impeller is open, the exposed blade and the corresponding wear plate shall be processed and inspected with a sample plate.

2) After finishing the processing of wear plates and exposed blades, they shall be grinded and painted for inspection. The uniform contact area shall not be less than 50%. Once this work is done, it must not be neglected.